2013

Joseph Millette

Sophisticated R/C

9/13/2013

Ardu-Copter Setup and Tuning 

Manual
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Table of Contents

What is a Multi-Copter and How Does it Work ............................................................................................7

The Multi-Copter System..............................................................................................................................9

Multi-Copter Demo illustrating Manual and Automatic Control..................................................................9

Important Elements for Multi-Copters.......................................................................................................10

Significant Design Considerations for Multi-Copters..................................................................................11

Ready To Fly or Build Your Own..................................................................................................................12

DIY-Drones..................................................................................................................................................13

APM: Copter Safety – Read Before Flying...................................................................................................14

First Flight....................................................................................................................................................20

Setting up Flight Modes..........................................................................................................................20

Simple and Super Simple Modes ............................................................................................................21

Normal Mode..............................................................................................................................................22

Simple Mode...........................................................................................................................................23

Super Simple Mode.................................................................................................................................26

Use a 3 position switch to select Normal, Simple or Super Simple Mode..............................................27

Stabilize Mode ........................................................................................................................................29

Overview.................................................................................................................................................29

Moving the Pitch and Roll...................................................................................................................29

Moving the Yaw ..................................................................................................................................29

Moving the Throttle............................................................................................................................29

Tuning PID...........................................................................................................................................29

Tuning Yaw..........................................................................................................................................30

Altitude Hold Mode ................................................................................................................................32

Overview .............................................................................................................................................32

Using Alt Hold Mode...........................................................................................................................33

Adequate Power and Adjusting your Throttle Center position to Hover...........................................33

Tuning .................................................................................................................................................34

Loiter Mode.............................................................................................................................................36

Overview .............................................................................................................................................36

Using Loiter Mode...............................................................................................................................37

OF_Loiter Mode ..................................................................................................................................37
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Tuning .................................................................................................................................................37

RTL Mode ................................................................................................................................................39

Overview .............................................................................................................................................39

Options (User Defined Parameters.....................................................................................................40

Notes...................................................................................................................................................40

Auto Mode ..............................................................................................................................................42

Overview .............................................................................................................................................42

Using Auto Mode from Ground and from the Air...............................................................................43

Ending a Mission .................................................................................................................................43

Tuning .................................................................................................................................................43

Guided Mode ..........................................................................................................................................44

Overview .............................................................................................................................................44

What you’ll Need ................................................................................................................................45

Instructions.........................................................................................................................................45

Board LEDs and Sounds...............................................................................................................................47

APM 2.5/2.6 ............................................................................................................................................47

3DR GPS+Compass Module.................................................................................................................47

Pre-Arm Safety Checks(PASC).....................................................................................................................48

To See what has caused the PASC Failure ..............................................................................................48

Fixing Specific PASC Failures...................................................................................................................49

Arming and Disarming the System..............................................................................................................50

Arming the Motors..................................................................................................................................50

Disarming the Motors.............................................................................................................................50

Rate Roll and Pitch P Tuning .......................................................................................................................51

Measuring Vibration ...................................................................................................................................53

Save Trim and Auto Trim.............................................................................................................................56

Save Trim.................................................................................................................................................56

Auto Trim ................................................................................................................................................57

Flight Test Process.......................................................................................................................................59

To Test Loiter and Altitude Hold:............................................................................................................59

What to Expect?......................................................................................................................................59

Advanced Configuration and Tuning ..........................................................................................................61
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Compass Setup............................................................................................................................................62

Live Calibration of compass offsets ........................................................................................................62

Compassmot-compensation for interference from the PDB, ESC, or motors........................................63

Tuning Declination in-flight.....................................................................................................................64

Automatic learning of offsets during flight.............................................................................................65

Log based calibration of offsets..............................................................................................................65

Manually entering declination................................................................................................................66

Fail-safes .....................................................................................................................................................68

Throttle Fail-safe.....................................................................................................................................68

Throttle Fail-Safe Setup ..........................................................................................................................69

Receiver set-up: ..................................................................................................................................69

APM Setup ..........................................................................................................................................69

Testing for correct operation of Throttle Fail-safe .................................................................................70

Battery Fail-safe ......................................................................................................................................71

GPS Fail-safe............................................................................................................................................72

Ground Control Station Failsafe..............................................................................................................72

Geo-Fencing ................................................................................................................................................74

Overview.................................................................................................................................................74

Enabling the Fence in Mission Planner...................................................................................................75

Enabling the fence with Channel 7 or 8..................................................................................................75

Setting Channel 6, 7, or 8 options...............................................................................................................77

Here are the options:..........................................................................................................................78

Check Ch7 & Ch8 PWM values reach 1800.............................................................................................78

Tuning .........................................................................................................................................................79

Basic performance troubleshooting .......................................................................................................80

In-flight tuning ........................................................................................................................................82

Here are all the parameters one can tune:.............................................................................................83

Method 2: Flying Attitude Tuning with CH6: ..........................................................................................84

Attitude PID Tuning.....................................................................................................................................85

Overview.................................................................................................................................................85

PID Rate Tuning.......................................................................................................................................85

PI Control Tuning ....................................................................................................................................86
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Altitude Hold Tuning ...................................................................................................................................87

PI Control ................................................................................................................................................87

PID Rate Control......................................................................................................................................87

Loiter and Navigation Tuning......................................................................................................................88

PI Control ................................................................................................................................................88

PID Rate Control......................................................................................................................................88

Sensor Testing.............................................................................................................................................89

Connecting to Mission Planner...............................................................................................................89

Mission Planning and Analysis....................................................................................................................90

Here are some of the features of Michael Oborne’s Mission Planner: ..................................................90

Planning a Mission with Waypoints and Events.....................................................................................90

Basic Waypoint Commands ....................................................................................................................91

Tips......................................................................................................................................................91

Setting a Home Position..........................................................................................................................92

Instructions.............................................................................................................................................92

Auto Grid.............................................................................................................................................94

Basic Waypoint Commands ................................................................................................................94

Data-flash Logs............................................................................................................................................98

Log Types (Data-flash vs. tlog) ................................................................................................................98

Setting what data you want to record....................................................................................................98

Downloading Logs with the Mission Planner........................................................................................101

Viewing the contents............................................................................................................................102

Message Details (APM: Copter specific) ...............................................................................................104

Viewing KMZ FILES ................................................................................................................................109

Mission Planner Telemetry Logs...............................................................................................................110

Setting the data rate .............................................................................................................................110

Playing back missions............................................................................................................................110

Creating 3d images of the flight path ...................................................................................................112

Extracting parameters and Waypoints .................................................................................................112

Graphing data from a flight...................................................................................................................113

Using a Ground Station.............................................................................................................................114

Guided Mode ........................................................................................................................................115
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APM 2.6.................................................................................................................................................116

Using the APM 2.5/2.6 Enclosure .........................................................................................................117

Powering the APM 2.5/2.6 Board .........................................................................................................117

Alternative ways to power your board.................................................................................................119

3DR Power Module...........................................................................................................................119

A Non technical Description of the Power Supply Requirements ........................................................119

Power Supply Rails Connected Requirements (JP1 Installed) ..............................................................120

No Power Module and No Servos and Power provided by BEC from ESC............................................120

No Power Module but using Servos and a high power External BEC ...................................................120

No Power Module but using Servos and multiple BECs from ESC’s (A BEC for each Servo) ................121

Power Supply Rails Not Connected Requirements (JP1 Not Installed).................................................121

Power Module and No Servos ..............................................................................................................121

Power Module and using Servos with External BEC power..................................................................122

Power Module and using Servos with BEC power from one ESC .........................................................122

Power Module and using Servos with BEC power from one ESC .........................................................122

No Power Module and using Servos with BEC power from two ESCs..................................................122

APM 2.5/2.6 Connections.........................................................................................................................124

Connecting your R/C Inputs and Motors..................................................................................................125

Connecting the RC inputs......................................................................................................................125

Connecting the RC Outputs to the Motors...........................................................................................126

Recognizing the clockwise and counter-clockwise propellers..................................................................128

Checking the motor direction the simple way......................................................................................129

Checking the motor direction with the CLI...........................................................................................129

Glossary.....................................................................................................................................................131

Pitfalls/Lessons Learned............................................................................................................................136

Introduction ..........................................................................................................................................136

Assembly ...........................................................................................................................................136

Configuration ....................................................................................................................................136

Flying .................................................................................................................................................137
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Revision History

Date Changes
Page | 8

What is a Multi-Copter and How Does it Work

A multi-copter is an aerial vehicle whose motion is controlled by speeding or slowing 

multiple downward thrusting motor/propeller units.

 A Multi-Copter is one of the simplest powered aerial vehicles imaginable: A bunch of fans 

pointing at the ground which pushes you up.

 Multi-Copters are completely aerodynamically unstable and absolutely require computer 

control for stable flight.

 As a result, Multi-Copters are entirely “Fly by Wire” systems and if the computer isn’t working, 

you aren’t flying.

 The Quad-Copter shown above is the simplest type of multi-copter, with each opposite pair of 

motors spinning in opposite directions.

 This allows the copter to turn (Yaw) right or left by speeding up one pair and slowing the 

other pair of motors.

 Horizontal motion is accomplished by speeding up motors (increasing thrust) on one side and 

reducing it on the other.

 This causes the copter to tilt (Roll or Pitch) in the desired direction of motion and thrust 

is re-equalized.

 The angle of the copter is generally representative of its speed in that direction.

 To hover the copter compensates for disturbances (gusts of wind) by tilting automatically 

against the direction of the disturbance.

 In order to accomplish this, the copter has electronic “gyros” which sense level in 3 

dimensions.

 In addition, they may also have electronic “accelerometers” which sense displacement 

in 3 dimensions.

 Altitude control or change is accomplished by speeding up or slowing down all motors at the 

same time.
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The Multi-Copter System

In order to be able to fly you need:

 The Multi-Copter itself, including the frame, motors, electronic speed controls, propellers and a 

battery.

 A Flight Control computer or Autopilot provides stabilization and in more advanced systems (as 

above), automatic control.

 A radio control transmitter and receiver in order to send the Multi-Copter your own 

instructions.

 A personal computer in order to program the computer and optionally for use as a telemetric 

ground station.

Multi-Copter Demo illustrating Manual and Automatic Control

 The demo begins in “Stabilize Mode” which provides inertial stabilization and permits manual 

flight control.

 In “Loiter Mode” the Copter automatically maintains position and altitude but permits manual 

override.

 “Simple Mode” enables the copter to be flown without regard to the copters orientation (the 

direction it is facing).

 “Auto Land” causes the copter to descend and disarm its motors when it has landed.
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Important Elements for Multi-Copters

 The primary requirement of a Multi-copter is that it possess more than sufficient power propel 

itself straight up.

 Multi-Copters have been made feasible by the development of extremely powerful 

Lithium batteries.

 Previous battery technologies have insufficient capacity and are too heavy for a 

reasonable duration of hovering flight.

 Brushless electric motors and electronic speed controllers also enhance flight performance, 

endurance and reliability.

 Carbon fiber, aluminum and fiberglass make strong light frames possible further increasing 

efficiency and performance.

 The Flight Controller / Autopilot / Computer are the brain that lets the Multi-Copter accomplish 

marvelous things.

 Our group relies on the APM, PX4 and Pixhawk Flight Controllers and they each have 

considerable capability.

 The Flight Controllers contain or attach to the wide variety of sensors necessary for 

automatic control.

 Ours systems include: 3 axis gyro, 3 axis accelerometer, compass/magnetometer, 

barometer/altimeter and GPS.

 The Autopilot interfaces to the copters motors, radio control receiver and optional 

telemetry and camera controls.

 Modern 2.4 GHz radio control systems provide fast and very reliable in flight communication 

with the multi-copter.

 An excellent Mission Planner computer program allows us to load the operational “firmware” 

into the Autopilot.

 The Mission Planner program also permits us to load custom parameters and 

instructions to our Multi-Copter.

 Additionally we can use the Mission Planner to read and analyze flight logs recorded to 

the Autopilot while in flight.

 Finally the Mission Planner program can operate as a telemetric “Ground Station” 

displaying current flight data.
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Significant Design Considerations for Multi-Copters

 A Multi-Copter is a highly stressed system so it is important that all components are carefully 

matched to its capability.

 Projected weight, performance, flight time and payload all require careful balancing to 

achieve a good result.

 A high performance, light weight Quad-Copter has different needs than a heavy lift, 

camera carrying Hex or Octo-Copter.

 Frame size and weight, motor/prop requirements, power (battery) needs, and payload 

are important considerations.

 A small Quad-Copter is ideal to learn to fly on. They are easy to fly, light, tough, relatively safe 

and survive mishaps well.

 A big Hex or Octo with a camera rig is seriously expensive, much more hazardous and is 

inappropriate to learn on.

 It will also tend to break much more destructively (and expensively) than a relatively 

light and unencumbered Quad-Copter.
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Ready To Fly or Build Your Own

 There are excellent arguments on both sides of this issue, you can buy excellent ready to fly 

Copters or easily build your own.

 You can get tiny little toy grade Quad-Copters for under a hundred dollars with everything that 

are still remarkably easy to fly.

 Some are so small that they represent very little hazard even indoors and they are so 

light that they are also very sturdy.

 The tiny Traxxas QR1 Quad-Copter is an excellent and inexpensive RTF Quad-copter 

that is great for a first experience.

 Alternatively you might consider an inexpensive ARF “Almost Ready to Fly” semi build it yourself 

approach.

 The DJI Flame Wheel F450 and F330 ARF kits are an excellent value and we have a Wiki 

walk through assembly page.

 These Copters will survive many hours of “learning” and the walk through article utilizes 

our state of the art flight controllers.

 My little F330 with an APM 2.0 Flight Controller below has logged (Many) hours and 

survived numerous sub-optimal “landings”.

 Photography is not my thing, but click on it for a bigger picture.

 You can also start with an excellent configurable kit Quad-Copter such as the Ardu-Copter shown at 

the top of this page.

 Or the new state of the artIris Quad-Copter that incorporates the very powerful Pixhawk flight 

controller and advanced construction.
Page | 13

DIY-Drones

 Our group DIY-Drones are primarily devoted to automatic control and our emphasis is on the 

use of highly capable flight controllers.

 We seek to have lots of automatic and robotic capabilities such as precision point to point 

travel, waypoints and mission following.

 The APM, PX4 and Pixhawk flight controllers manufactured by 3DR, our supporting Corporation 

embody those capabilities.

 You can certainly start with and enjoy a little RTF Traxxas to get your feet wet and see if this 

appeals to you.

 But when and if you want to go to the next level, DIY-Drones stand ready to help you reach for 

the sky.

 We are the leading (and bleeding) edge but no-body offers you more opportunity to do more, 

more quickly than DIY-Drones.
Page | 14

APM: Copter Safety – Read Before Flying

Your first priority must be the safety of people!

1. Crashes can happen, because of pilot error or hardware or software malfunction.

2. It is very important to have excess power available.

A. If you have insufficient power, the automatic controls can require more throttle than is 

available and destabilization may result.

B. Ideally your copter should be able to hover at about 50% throttle (mid stick).

3. Especially while you are learning, it is recommended that you avoid expensive, stiff, ultrasharp carbon fiber props.

A. Get cheaper, more flexible and more breakable plastic propellers.

B. Some of the super carbon fiber ones can cut well than a Ginsu and while they are almost 

indestructible – You are not.

4. If you are flying anywhere near other people, you are putting them at risk!

A. Be sure to maintain safe distances between yourself, and spectators and your copter.

B. Circumstances will require that you will need to make your own determination of what 

is a “safe distance” from people and property.

C. At a minimum, consider: at least 10ft (3m) but not further than 30ft (10m) from you.

D. Keep all other people, property and obstacles considerably further away from your 

copter.

E. Ensure that no one gets between you and your copter.

F. Spectators should always be a safe distance behind the pilot.

G. If people intrude beyond what you have determined to be the “safe” area, land 

immediately and do not take off until they are clear.

H. At full power, an average sized multi-copter can exceed 20 mph (32 km/h), can ascend 

to hundreds of feet and easily travel more than a mile in distance before running out of 

battery.
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5. Always ensure the battery cable is NOT connected to the power distribution board or harness 

until you are ready to fly.

A. Always turn on the transmitter and ensure the throttle stick is all the way 

down BEFORE connecting the battery.

B. After landing the first thing you should do is disconnect your battery cable.

C. Do not turn off the transmitter until after you have disconnected the battery.

D. Always remove your props while you are testing motors, your hands, arms and face and 

those of your friends will thank you.

E. When the battery is connected, always assume the motors are armed; you can check 

with a short throttle pulse.

F. Don’t pick up the model and the radio at the same time, you may bump the throttle.

G. Do not attempt to fly longer than your batteries safe capacity, it is very bad for the 

battery and can cause a crash.

6. The APM and PX4 flight controllers we use incorporate a motor arming safety feature.

A. Immediately prior to flight after the battery has been connected, the RC transmitters 

throttle stick needs to be held down and to the right for several seconds to arm the 

motors.

B. After landing your first response should be to hold the throttle down and to the left for 

several seconds to “Disarm” the motors. * Disarm condition can be tested by moving 

the throttle stick up, if the motors do not move it is disarmed.

C. Even when disarmed, the throttle stick should always be kept in the full down position 

except when flying.

7. Get used to switching back to Stabilize mode from other modes and reassuming full manual 

control.

A. This is the single most important recovery technique (practice it).

B. Stabilize mode can have Simple mode added to it, but if you do you should then practice 

with it till you are proficient.

C. Do not start using any other modes than Stabilize or Stabilize plus Simple until you are 

VERY comfortable flying your copter.
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8. Important primary response to a crash, inadequate landing or unknown flight controller state.

A. The first thing to do is throw a towel over your copters propellers (Propellers may start 

spinning unexpectedly).

B. Then immediately disconnect the battery.

C. A large towel is your most important piece of safety equipment followed by a fire 

extinguisher and a first aid kit.

D. Generally better to use the first one than the last one.

9. When testing or flying any of the (waypoint) navigation modes (using GPS):

A. Ensure that your GPS has “Lock” before arming and takeoff.

B. Check that your home position on the Mission Planner is in fact correct.

C. If the GPS does not accurately report your home position, reboot and wait for 8 or more 

satellites (not just 3D lock) and check again.

10. Always follow the law:

A. Our personal use of Multi-Copters (models in general) is continually under attack by 

those who fear ‘drones’ and invasion of privacy. If you break the law, or invade 

someone’s privacy, or put them in harm’s way, you threaten the future of our personal 

use of models. Please, understand the law and the rights of others – and fly accordingly.

B. Most countries have a prominent model aircraft organization. In the USA that is 

the AMA. Review the AMA safety code. Working with the FAA and other government 

organizations, the AMA has established (and continues to update) rules for UAV’s and 

for FPV flight. If you are in the USA (or not), read these documents! The AMA has a 

strong lobbying group that will help protect our rights. Get involved and support your 

country’s model aircraft organizations – and help protect our right to fly.
Page | 17

Most important: Keep a safe distance between your Copter and People!

These tips can also help protect your multi-copter from damage.

1. Avoid sudden or extreme transmitter control stick deflections.

A. Move the control sticks in small measured increments and don’t “yank” on them.

B. If the copter is properly calibrated and balanced it should require only small stick inputs 

to control altitude, direction and speed.

2. Your copter should be more or less stable on the horizontal plane without any control inputs.

A. If you are “fighting” the copter, land and fix it – something is not right – Hardware 

adjustment or software calibration may be required.

3. Be especially careful of large throttle inputs, as a copter can gain (or lose) 

altitude very rapidly.

4. Because Multi-Copters are symmetrical it is especially easy to lose Visual Orientation.

A. For manual flight modes, maintaining a clear vision of the Copters Orientation (direction 

it is facing) is the most critical part of successful flight.

B. Especially while learning it is very important to keep your copters appropriately close to 

you to aid in maintaining visual orientation.

C. Generally: more than 10ft (3m) but not further than 30ft (10m) from you.

D. If the copter gets further than about 100ft (30m) it starts getting difficult to be able to 

maintain orientation and can easily crash.

E. If you lose Yaw orientation while flying in Stabilize mode, try only flying forward and 

using yaw to steer like a car.

F. It is much better to simply descend and land rather than have an orientationinduced crash or worse still – a fly away.

G. Fly-Always often happen when the copter is commanded to tilt back towards the pilot 

but has rotated in the meantime and is so far away that orientation is lost.

H. Result: the copter flies further away and crashes or is lost.

5. Always have Stabilize mode as the (Go To) one of your mode switch options.
Page | 18

6. High or unexpected winds or gusts can make flight considerably more difficult.

A. High winds can prevent forward progress or spin the copter around causing you to 

become disoriented.

B. The higher you are, the more likely high winds will be a problem.

C. Switching to Stabilize mode and landing before you reach your skill limits can help you 

save your copter.

D. Avoid flying at high speed or high altitude until you have gained considerable confidence 

in both manual and automatic modes.

E. When flying around trees or buildings it is very easy to lose visual orientation or even to 

lose sight of the copter completely.

F. Gusting winds around objects can also worsen the problem.

G. Radio signal loss can also occur.

H. If your copter is approaching a potentially interfering object, immediately switch to 

stabilize mode and land or retrieve the copter to your location.

7. Ardu-Pilot specific safety modes: RTL, Fail-Safe and Geo-Fence.

A. RTL can provide a safe Return to launch if it starts to get away from you.

B. Set up a Fail-Safe on Radio Fail with an RTL or Descend response to save your Copter 

and prevent Injury.

C. Geo-Fence establishes an automatic flying perimeter that will force your copter to stay 

in a safe proximity.

D. Do not rely solely on the above safety modes, always be ready to take back control in 

stabilize and set the copter down.

E. Especially do not rely on the above safety modes to perform maneuvers or training that 

you would otherwise consider dangerous.

F. These modes are a supplement to, not a replacement for sound safety practices.
Page | 19

8. On your first takeoff after tuning or hardware setup:

A. In stabilize mode advance the throttle very slowly until the copter is almost hovering.

B. If the copter is trying to flip over turn it off and correct the problem.

C. A motor could be turning the wrong direction.

D. Or a wrong direction prop could be installed.

E. If it tries to rotate on its axis or fly off in some direction.

F. The transmitter or RC setup in Mission Planner may be incorrect.

G. A motor or ESC may not be performing properly.

H. The wrong props may be on the wrong motors.

I. When all problems are fixed it should be fairly easy to get the copter to hover a foot or 2 

above the ground.

J. If a stable and stationary hover a foot or 2 above the ground cannot be achieved, land 

and fix the problem until it can.

9. When flying FPV “First Person View” (with a video camera), Have your modes set to: 

STABILIZE, SIMPLE, and RTL.

A. Ensure RTL is working properly before using FPV.

B. Use Stabilize mode to fly FPV.

C. If you lose your FPV video, you can switch to Simple or RTL to get back.

10. Make sure your battery can’t fall out.

A. Use a Velcro Strap to hold it in place.

B. You can also use adhesive backed Velcro under the battery.
Page | 20

First Flight

This section covers the information you will need to know for your first flight and also some basic 

configuration to get your copter flying reasonably well. Please follow each of the links below.

Setting up Flight Modes

There are 13 flight modes available in APM: Copter, 9 of which are regularly used. You can set these up 

by doing the following:

 Turn on your RC transmitter

 Connect the APM/PX4 to the Mission Planner

 Go to the Software > Flight Modes screen

 Note as you move your transmitter’s flight mode switch (channel 5) the green highlight bar will 

move to a different position.

 Use the drop-down on each line to select the flight mode for that switch position ensuring that 

at least one switch position is left assigned to Stabilize

 Optionally check the Simple Mode checkbox for that switch position 

 When finished press the “Save Modes” button.

In general when first starting to use APM: Copter you should progress through the flight modes in 

the order listed below, being sure that you are comfortable with each before progressing to the 

next. Click on any of the flight modes below for more details.

 Stabilize

 Alt Hold

 Loiter
Page | 21

 RTL

 Auto

 everything else including ACRO, Guided, Circle, Position, LAND

Most transmitters provide a 3 position switch. 

If you do not wish to use the mission planner you can also set the flight modes through the CLI 

(command line interface).

With some small code modifications you can set-up custom flight modes which are combinations of 

existing flight modes as described in the developer section.

Simple and Super Simple Modes

 Simple Mode and Super Simple Mode are used in combination with the other Flight Modes.

 These modes can:

 Greatly simplify learning how to fly.

 Provide useful photo and video capability permitting the yaw to be used to “aim” the 

camera.

 Permit regaining control if the pilot loses sight of the visual orientation of the copter. 

Copter’s orientation is not apparent.

 These modes work by setting the copter’s orientation relative to a fixed direction or location 

regardless of the actual orientation of the copter.

 Simple Mode allows you to fly your copter relative to the copters orientation at take off.

 And Super Simple Mode allows you to fly (even more simply) relative to your home 

location.

 After takeoff in either Simple or Super Simple mode actual copter orientation (Yaw) is irrelevant, 

and the following controls apply: Pitch out = away, Pitch back = return and Roll left = go left, Roll 

right = go right.

 One of most important uses of Simple and Super Simple mode is to allow you to recover from 

loss of visual orientation of your copter.

 This is a very common problem for copters as visual orientation is often hard to 

determine or maintain even under ideal conditions.

 Although flying with Simple or Super Simple modes is much easier than normal flight it can 

initially be confusing especially for experienced RC pilots used to flying Normal mode.
Page | 22

 For this reason it is a very good idea to get used to flying in both Simple Modes before 

depending on them in an emergency.

 If you do switch to Simple mode in flight you need to be facing the same direction as you were 

at takeoff.

 If you do switch to Super Simple mode in flight you need to be standing approximately at your 

launch location

Normal Mode

 In Normal Modes flight and transmitter stick position is relative to the Orientation of the copter.

 This means that with the copter oriented away from you and flying away from you the 

controls operate as you would expect.

 But flying back towards you and oriented towards you, the controls are reversed.

In Normal mode fly from the standpoint of the copters orientation (as though 

you were a pilot in the copter).
Page | 23

Simple Mode

Simple mode is similar to the “care free” mode on other multi-copters.

 Simple mode allows you to “fly the compass, not the copter”.

 You fly your copter as though it were pointed in the direction it was pointed at take off 

regardless of its subsequent orientation.

 So, basically you can fly it all around you so long as you face the same direction as at take off.

 If you stand behind your copter and take off with it pointed directly away from you it 

will fly normally.

 But if you yaw the copter sideways it will still fly as though it were pointing directly away 

from you.

 Basically pitch forward on stick = copter going away from you, pitch back = copter 

coming back to you.

 And Roll left on stick = copter goes to the left, Roll right = copter goes to right.

 As long as you face the same direction the copter will go in the stick direction regardless 

of its orientation (yaw).

 You can spin it in any direction you wish and the copter will still behave exactly as it did 

at take off.

 Simple mode is a very easy way to fly!

 Simple mode solves the problem of maintaining visual orientation which is easily lost on any 

copter.

 You don’t need to worry about the orientation of the aircraft; you just fly according to your 

launch position.

 Basically if you start with the copter facing North, North is always “forward” in your RC stick 

position.

 Simple mode is actually a flight style modifier for the other flight modes of APM: Copter and is 

used in conjunction with them.

 Simple Mode is specified by checking the Simple Mode box next to the flight mode it is wished 

to modify in the Flight Modes section of the Configuration tab of the Mission Planner.

 Since simple mode uses the initial compass direction to determine (virtual orientation), it does

not require GPS lock.
Page | 24

In Simple Mode stay facing the same direction and even if you move around, the copter will always fly as 

described. This animation shows simple mode at work with rolling right and pitching forward as 

examples. The spinning copter shows how, no matter which way the copter faces, the controls remain

constant.
Page | 25

 To use Simple mode set the copter on the ground pointing away from you.

 Arm the copter. (Unless one of the primary Flight Modes requires GPS it is NOT 

necessary to acquire GPS lock).

 Advancing the Pitch control stick forward causes the copter to fly away from you and 

Pitch back causes it to fly towards you.

 Moving the Roll control stick to the right causes the copter to go to the right and Roll 

left causes it to go to the left.

 Moving the Yaw control stick causes the copter to rotate, but its heading does NOT 

affect direction the copter will go when the Pitch or Roll control is used.

 The Throttle control stick controls altitude as is normal for whichever mode is selected 

as being under Simple mode control.

 For Simple mode the desired orientation is set when the copter is armed.

 Re-arming the copter will reset the “home” orientation.

 Simple mode can be selected as the manual control mode of any other mode, as shown 

in the Mission Planner setup screen above.

 Simple mode is especially useful for flying at the edge of visual range, but not so useful for FPV.

 If your copter has gotten to be too far away you can use a Simple mode specified 

Stabilize mode to bring it back to a closer range without using RTL mode (RTL does not 

work if the GPS has no fix).

 Simple mode can even be useful for mechanical failure recovery.

 You could lose a motor on a hex or Octo setup causing your copter to spin.

 If you switch to a simple mode it can allow you sufficient control to recover and land the 

copter.

 Providing you have sufficient power in your remaining motors to maintain altitude.

 Simple mode can also be changed with Channel 7 and 8 input.

 If you choose this option of enabling Simple mode via Channel 7 or 8, your normal mode switch 

settings will be overwritten.

 You can also enable Simple mode via the CLI.

 To enable Simple mode individually, per switch position, open the CLI and go to “setup” 

and “modes”.

 Use the roll control to set the mode per switch position.

 Use the rudder control to set the Simple mode option per switch position.

WARNINGS:

 When using Simple Mode, you (the pilot) must stay in the same orientation.

 If you turn 90°, then pitch will become roll!

 If you want to rotate yourself and keep Simple mode – - simple, you need to land, 

disarm and reorient the front of the copter to your new away from the pilot direction 

and then re-arm and take off.
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Super Simple Mode

 Super Simple Mode uses your home position to maintain orientation rather than initial vehicle 

orientation.

 So basically you can fly it all around you changing your and its orientation so long as you stay on 

the same spot.

 This mode does require GPS lock because (virtual orientation) is relative to launch spot rather 

than launch orientation.

 Super Simple mode uses your home position as the reference for forward.

 If you fly > 10m away, the copter will constantly recalculate it’s orientation so that:

 Pitch forward moves the copter away from you

 Pitch back moves the copter towards you

 Roll Left causes the copter to orbit counter clockwise around you towards the 

left.

 Roll Right causes the copter to orbit clockwise around you towards the right.

 The Yaw control stick will cause the copter to rotate, but its heading does NOT 

affect direction the copter will go when Pitch or Roll control is used. (Roll and 

Pitch motion is relative to the GPS home position determined at take off not 

relative to copter heading).

 The Throttle control stick controls altitude as is normal for whichever mode is 

selected as being under Super Simple mode control.

 This makes for very intuitive flying and removes the need to worry about the original 

orientation.

 Inside the 10m circle, the most recent orientation is kept.

 In order to successfully use Super Simple mode:

 You must use the GPS and you must set home by achieving GPS lock (GPS blue LED and 

APM blue LED on solid not blinking) before arming and takeoff.

 If you fly around and achieve lock in the air, this will be your new home location.

 Flying 10m from this location will suddenly reorient the copter.

 To avoid this issue wait till you have GPS lock (GPS blue LED and APM blue LED on solid 

not blinking)before arming and flying when you are going to use Super Simple mode.

 As long as you stay in the same spot, as you fly the copter around you and regardless of the 

direction you (or it) are facing.

 It will always go directly away from you if you pitch forward and return to you if you 

pitch back.

 And it will always go to the left if you roll left or go to the right if you roll right.

 Super Simple mode is enabled by setting the parameter named SUPER_SIMPLE to 1 

(0 disabled default) in the Parameter List in the Mission Planner’s Configuration section.

 When SUPER_SIMPLE is enabled all modes selected as simple will be in fact Super 

Simple.

 Really Super Simple right!
Page | 27

In Super Simple Mode, stay at the launch location and even if you turn around with 

the copter in front of you it will fly as described.

Use a 3 position switch to select Normal, Simple or Super Simple Mode

 A two position switch will select between Normal and either Simple or Super Simple operation 

as illustrated below.

 In Mission Planner select either channel 7 or channel 8 and then select either “Simple 

Mode” or “Super Simple Mode”.

 Warning! The 3 Position Switch Option will not be available until version 3.1 of the Ardu-copter

firmware.

 A 3 position switch connected to either Ch7 or Ch8 will select between Normal, Simple 

and Super Simple Modes.

 For 3 position switch operation, in Mission Planner set channel 7 or channel 8 to “Super 

Simple Mode”.

 For 3 positions switch operation insure that your switch low PWM is below 1200 and 

your high PWM is above 1800.

 For a three position switch, the assignments are as follows.

 Low position : Disable (Normal operation)

 Mid position : Simple mode enabled

 High Position: Super Simple mode enabled.
Page | 28

 In addition to safe recovery, the ability to select between modes can be especially useful for 

filming and photography.

 It can allow the copter to be pointed (yawed) as desired for the camera orientation 

while permitting normal flight control.
Page | 29

Stabilize Mode

Stabilize mode is APM: Copter’s manual flight mode. This page provides tips for flying in stabilize and 

methods for tuning your copter to fly optimally in stabilize mode.

Overview

Stabilize mode is the primary operating mode for flying APM: Copter and can be considered its manual 

flight mode. Stabilize automatically levels the multi-copter and maintains the current heading, while 

allowing the pilot full control over the throttle. Stabilize is good for general flying and FPV. The autopilot 

must always initially be set to stabilize mode in order to be able to arm the ESCs before takeoff. It is 

VERY important to be able to easily and rapidly switch back to stabilize mode from any other mode in 

order to regain control from any unexpected or undesirable flight behavior.

Moving the Pitch and Roll

 Moving the (right) control stick in any direction will cause the copter to tilt and move in that 

direction.

 Releasing the Pitch and Roll control stick will cause the multi-copter to re-level itself.

 Input on the (Pitch and Roll) control stick is approximately equal to the angle of the copter.

 The default control angles are plus and minus 45 degrees.

 Prevailing wind is not automatically compensated for and the multi-copter will drift with the 

wind unless the operator counters with input on the Pitch and Roll control stick.

Moving the Yaw

 Moving the (left) control stick left or right will cause the copter to rotate at a rate based on the 

amount of stick input.

 Releasing the (Yaw) control stick will cause the copter to record and maintain the new heading.

 The current heading is maintained automatically when the Yaw control stick is centered right 

and left.

Moving the Throttle

 Moving the (left) control stick up or down will cause the copter to ascend or descend 

accordingly.

Tuning PID

 The Stabilize Control PI and Stabilization Angular Rate Control PID interacts to control the 

copter in Stabilize mode.

 The Stabilization Angular Rate P value is the single most important value to set correctly for 

your copter.

 The higher performance your copter is, the lower this number should be.

 A copter that accelerates very quickly might have a number like 0.08 and one that is 

more sluggish could have a number like 0.18.

 If you get this right generally your copter will fly acceptably in all modes, but tweaking 

the PIDs for your copter will let you optimize performance.
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 The RATE_RLL PID and RATE_PIT PID are normally locked to the same values as the Angular Rate 

Control PID in the Mission Planner.

 The STB_PIT PI and the STB_RLL PI are normally locked to the same values in the 

Stabilize Control PI in the Mission Planner.

 For most copters the Roll and Pitch PID values should be the same.

 See AC2_attitude_PID for more detailed tuning information.

 Stable_P is used input the rate of rotation based on control input.

 The higher the P the faster the copter will be asked to turn to get to the desired angle.

 A high P will cause the copter to oscillate back and forth like a seesaw a few times a 

second.

 A low P will cause the copter to move very slowly. A very low P will cause the copter to 

feel unresponsive and could cause a crash if the wind disturbs it.

 Stable_I is used to compensate for outside forces that would make your copter not maintain the 

desired angle.

 The I term will ramp to hold the desired angle.

 Because the copter rotates to new angles constantly, the I-term is not that useful in this 

mode.

 It is used instead to try and hold the copter perfectly level when hovering.

 A limit to the ramp up of the I-term has been set low to achieve this.

 The output of the Stabilize Control PID is sent to the Angular Rate Control PID whose output 

directly controls the copters motors.

 Rate_P is used to turn the copter.

 The higher the P the higher the motor response to achieve the desired turn rate.

 This is the single most important value to tune correctly for your copter.

 Default is P = 0.18 for standard Ardu-copter.

 A higher performance copter might use a value of 0.08.

 Rate_I is used to compensate for outside forces that would make your copter not maintain the 

desired rate.

 A high I term will ramp quickly to hold the desired rate, and will ramp down quickly to 

avoid overshoot.

 A low I term will take too long to have an effect and may cause undesirable overshoot. 

It’s better to have an I-term of 0 than a poorly chosen I term.

 Rate_D is used to dampen the response of the copter to accelerations toward the desired set 

point.

 A high D can cause very unusual vibrations and a “memory” effect where the controls 

feel like they are slow or unresponsive.

 Values of .001 to .008 have all been used, but results will vary according to your multicopters size and performance characteristics.

Tuning Yaw

 Yaw Angular Rate Control and Yaw Stabilize Control is also basic functions for controlling the 

rate of heading change of the copter.
Page | 31

 Yaw Angular Rate Control Determines how much throttle is applied to rotate the copter at the 

desired speed.

 Yaw Rate P should be set higher to turn faster and lower to turn more slowly.

 Yaw Stabilize Control Determines how fast the copter responds to user or autopilot input.

 Yaw Stabilize P should be set higher get more aggressive control and lower to slow 

reaction time.

 Too high a Yaw Stabilize Control P value will cause slow wobbles.
Page | 32

Altitude Hold Mode

In altitude hold mode, the copter maintains a consistent altitude while allowing roll, pitch, and yaw to be 

controlled normally. This page contains important information about using and tuning alt hold.

Overview

When altitude hold mode (alt hold) is selected, the throttle is automatically controlled to maintain the 

current altitude. Except for automatic altitude maintenance, alt hold mode operates the same as in 

stabilize mode. Automatic altitude holding is a feature of many APM: Copter flight modes (such as loiter 

mode) and the information contained here pertain to those modes as well.

In versions 2.9 and later of the APM: Copter firmware, accelerometer-based “inertial compensation” is 

also used to maintain altitude. This results in faster compensation and more accurate altitude 

maintenance, but it also requires vibration damping for your flight controller mounting. Visit 

the Vibration Dampening page for more information about how to reduce vibrations in your copter.

Warning: The flight controller uses a barometer which measures air pressure as the primary means for 

determining altitude (“Pressure Altitude”) and if the air pressure is changing in your flight area, the 

copter will follow the air pressure change rather than actual altitude (unless you are within 20 feet of 
Page | 33

the ground and have SONAR installed and enabled). Below 26 feet, SONAR (if enabled) will automatically 

provide even more accurate altitude maintenance.

Using Alt Hold Mode

When entering alt hold, it is important to be hovering at a stable altitude before engaging alt hold. This 

is because when engaging alt hold (or any mode that maintains the present altitude automatically), the 

current throttle stick position is used as a baseline for altitude maintenance, so it is important to have 

the copter normally hovering near center stick position. The APM will compensate over time for rising or 

dropping and should end up at the correct altitude, but it is wise to not over depend on this 

capability. To adjust the position of the throttle stick so it hovers near the center stick position, see the 

section below on adjusting the throttle center. In all altitude holding modes the throttle stick controls 

the altitude, not motor speed directly.

While in alt hold mode, altitude can still be manually changed by raising or lowering the throttle control 

beyond a large central dead band. After using manual override to change altitude it is important to reposition the throttle stick back to as near your normal hover position as possible because altitude hold 

uses the RC transmitter throttle stick center position as the center point for all manual altitude 

adjustments. When you switch back to stabilize mode from any altitude holding mode, the copter will 

immediately go in the direction of any throttle stick displacement from the neutral hover position, 

potentially causing it to drop or rise at an alarming rate.

Altitude hold mode is not approved for takeoff and landing.

! Warning! You cannot land and turn off the motors in any altitude holding mode. Always switch to 

stabilize mode to be able to land and disable the motors.

Adequate Power and Adjusting your Throttle Center position to Hover

 It is very important to have excess power available.

 If you have insufficient power, the automatic controls can require more throttle than is 

available and destabilization may result.

 Ideally your copter should be able to hover at about 50% throttle (mid stick) and 

anything higher than 70% is dangerous.

 Once you have determined you have sufficient power you can adjust the throttle stick midpoint 

to be in the center.

 This is important, because when you switch to an Altitude Holding mode, actual stick 

center is used to determine static altitude.

 In an Alt Hold mode if you move the throttle past a + or – 10% dead band, manual 

override causes the copter to go up or down.

 The throttle dead band when in alt-hold or loiter mode is from 40% ~ 60% of the 

throttle.

 If you have an over or under powered copter the throttle required in stabilize to 

maintain a hover may be outside this range.
Page | 34

 The result being that when you enter an alt-hold mode your throttle is outside of the 

dead band and the copter will climb or descend.

 An operational solution is to simply move your throttle back to center as you engage althold.

 Adjust the THR_MID parameter in Mission Planner’s Adv Parameter List to allow the copter to 

hover at throttle stick center.

 If your copter hovers at 40% of throttle stick when in stabilize mode, make THR_MID = 

400.

 If it hovers at 60% of throttle make THR_MID = 600, etc.

 THR_MID total range is from 300 to 700 (30% to 70%) and any offset outside of that 

range is probably dangerous.

 Warning: If you incorporate expo on your transmitter, that directly increases the size of the Alt 

Hold throttle dead band.

Tuning

NOTE! This information does not yet take into account the effect of inertial compensation, Use Caution!

 The THR_ALT PI and THR_RATE PID interacts to control and adjust the copters altitude in any 

automatic altitude maintaining mode.

 See Altitude Hold Tuning for more detailed tuning information.

 Altitude Hold PI

calculates altitude error in centimeters and feeds it to the controller.

 The first stage of the controller takes the altitude error and decides how fast the copter 

should go to reach the correct altitude.

 THR_ALT_P is by default .4 or 40 cm/s for a 1m error.

 The desired rate maxes out at 1m/s.

 THR_ALT_I is used to close the gap between the actual hover throttle and current 

assumed hover throttle.

 For example, if your copter hovers at 52% throttle, and your set point is 4% your copter 

will fall until it reaches equilibrium with THR_ALT_P times the error.

 This is called a steady state error, and leaves your copter too high or too low.

 THR_ALT_I will increase to effectively raise the throttle to 52%.

 The higher the number the faster it happens.

 If your number is too high it will cause oscillations.

 Throttle Rate PID adjusts the motor thrust to provide the speed that is required from the 

THR_ALT PI.

 THR_RATE_P is the proportional response and the default is .35.

 Your copter will vary quite a bit depending on the weight and thrust of your motors.

 If your copter oscillates up and down in alt hold, lower this value.

 THR_RATE_I is set to 0 by default.

 It can, in theory, fix issues with a bad THR_RATE_P value, but it’s best to just get that 

tuned well in the first place.
Page | 35

 THR_RATE_D is 0.02 by default, but the noise of the Baro sensor can cause issues.

 If the value is too high you will see bad oscillations or pulsing of the motors.

 Once the THR_RATE_P value is dialed in, start at 0, and increment the D value slowly.

 You should see oscillations die down.
Page | 36

Loiter Mode

In loiter mode, the copter maintains a consistent location, heading, and altitude. This pages describes 

what to except when using loiter mode and provides tips for flying and tuning.

Overview

When switched on, loiter mode automatically attempts to maintain the current location, heading and 

altitude. Wind, PIDs and sensors will affect the effectiveness of maintaining position. The stronger the 

wind the greater the location deviation will be.

In loiter; the copter’s location can be manually adjusted with the control sticks.

 Horizontal location can be adjusted with the Roll and Pitch control stick.

 The Heading can be reset with the Yaw control stick.

 Altitude can also be adjusted with the Throttle control stick.

Since Loiter mode attempts to maintain position, it relies on the GPS which must be on and indicating 

that it is locked before takeoff. Ensure that both the GPS blue LED and the APM board C blue LED are on 

steady and not blinking before arming and taking off when Loiter mode is going to be used. For the 3DR 

uBlox GPS+Compass module, the blue LED is off while acquiring satellites and on blinking when satellites 
Page | 37

have been acquired. It is very important to acquire GPS lock before arming in order for RTL, Loiter, 

Auto or any GPS dependent mode to work properly.

Warning: In loiter mode, the flight controller uses a barometer which measures air pressure as the 

primary means for determining altitude (“Pressure Altitude”) and if the air pressure is changing in your 

flight area, the copter will follow the air pressure change rather than actual altitude (unless you are 

within 20 feet of the ground and have SONAR installed and enabled). Below 26 feet, SONAR if enabled 

will automatically provide even more accurate altitude maintenance.

Warning: Loiter mode is not approved for takeoff and landing. You cannot land and turn off the motors 

manually in Loiter mode. You must switch to Stabilize Mode to land and disarm the motors.

Using Loiter Mode

Loiter mode incorporates automatic altitude maintenance; therefore the same usage guidelines apply to 

altitude hold mode and loiter mode. When entering a mode that maintains the present altitude 

automatically, the current throttle stick position is used as a baseline for altitude maintenance so it is 

important to be hovering at a stable altitude before engaging loiter mode. The APM will compensate 

over time for rising or dropping and should end up at the correct altitude, but it is wise to not over 

depend on this capability. For more information on setting the throttle’s center, visit the Altitude Hold 

Mode page.

While in loiter mode altitude can still be manually changed by raising or lowering the throttle control 

beyond a large central dead band. After using manual override to change altitude it is important to reposition the throttle stick back to as near your normal hover position as possible. When you switch back 

to stabilize mode from any altitude holding mode, the copter will immediately go in the direction of any 

throttle stick displacement from the neutral hover position, potentially causing it to drop or rise at an 

alarming rate. Remember that, in loiter, the throttle stick now adjusts the altitude, not the motors 

directly.

OF_Loiter Mode

OF_LOITER is a special version of Loiter mode that will use the Optical Flow device to maintain position. 

It is not yet implemented but work is ongoing. Do Not select OF_LOITER mode until an update of APM: 

Copter specifies that it is installed and working.

Tuning

Tuning PIDs can improve all aspects, but over increasing responsiveness can result in sudden and 

unexpected loss of control.

 See Loiter and Navigation Tuning for more detailed tuning information.

 Loiter Speed PI and Loiter Rate PI values are used to control the copter.

 Loiter Speed P is used to push the copter to the desired location.

 Loiter Speed I is used to overcome wind.

 Loiter Speed I is overwritten by the copter on the fly and is not user editable.

 Loiter Rate P is used to tilt the copter.
Page | 38

 The higher the P the higher the motor response to achieve the desired turn rate.

 Loiter Rate I is used to compensate for outside forces that would make your copter not maintain 

the desired rate.

 A high I term will ramp quickly to hold the desired rate, and will ramp down quickly to 

avoid overshoot.

 A low I term will take too long to have an effect and may cause undesirable overshoot.

 It’s better to have an I-term of 0 than a poorly chosen I term.
Page | 39

RTL Mode

In return to launch (RTL) mode, the copter navigates from its current position to hover above the home 

position. The behavior of RTL mode can be controlled by several adjustable parameters. This page 

describes how to use and customize RTL mode.

Overview

When RTL mode is selected, the copter will return to the home location. By default the copter will first 

rise to at least 15m before returning home, or it will maintain the current altitude if it is higher.

RTL is a GPS-dependent move, so it is essential that GPS lock is acquired before attempting to use this 

mode. Before arming, ensure that the APM’s blue LED is solid and not blinking. For a GPS without 

compass, the LED will be solid blue when GPS lock is acquired. For the GPS+Compass module, the LED 

will be blinking blue when GPS is locked.

RTL will command the copter to return to the home position, meaning that it will return to the location 

where it was armed. Therefore, the home position is always supposed to be your copter’s actual GPS 

takeoff location, unobstructed and away from people. For APM: Copter if you get GPS lock and then 

ARM your copter, the home position is the location the copter was in when it was armed. This means if 

you execute an RTL in APM: Copter, it will return to the location where it was armed.
Page | 40

Warning: RTL travel speed is determined by WPNAV_SPEED. If you are using CH6 for WPNAV_SPEED 

setting from your RC radio, check that your CH6 receiver failsafe is set to a correct value or you could get 

a very slow RTL during a radio failsafe event.

Warning: In RTL mode the flight controller uses a barometer which measures air pressure as the primary 

means for determining altitude (“Pressure Altitude”) and if the air pressure is changing in your flight 

area, the copter will follow the air pressure change rather than actual altitude (unless you are within 20 

feet of the ground and have SONAR installed and enabled).

Options (User Defined Parameters

 RTL_ALT: The minimum altitude the copter will move to before returning to launch.

 Set to zero to return at the current altitude.

 The return altitude can be set from 1 to 8000 centimeters.

 The default return altitude Default is 15 meters (1500)

 RTL_ALT_FINAL: The altitude the copter will move to at the final stage of “Returning to Launch” 

or after completing a Mission.

 Set to zero to automatically land the copter.

 The final return altitude may be adjusted from 0 to 1000 centimeters.

 RTL_LOIT_TIME: Time in milliseconds to loiter above the “Home” position before beginning final 

descent.

 The “Loiter” time may be adjusted from 0 to 60,000 milliseconds.

 WP_YAW_BEHAVIOR: Sets how the autopilot controls the “Yaw” during Missions and RTL.

 0 = Never change Yaw.

 1 = Face Next Waypoint or for RTL face nose in (towards Home).

 2 = Face Next Waypoint or for RTL face nose out (away from Home).

 LAND_SPEED: The descent speed for the final stage of landing in centimeters per second.

 The landing speed is adjustable from 20 to 200 centimeters per second.

Notes

 Other navigation settings also have an influence over RTL mode:

 WPNAV_ACCEL

 WPNAV_LOITER_SPEED

 WPNAV_SPEED_DN

 WPNAV_SPEED_UP

 To use RTL, GPS lock needs to be achieved (Blue GPS LED and Blue APM LED on solid not 

blinking) before arming and takeoff to establish the home or launch position.

 Note on the UBLOX GPS module the LED is off while acquiring satellites and on blinking when 

satellites have been acquired.

 Landing and re-arming the copter will reset home, which is a great feature for flying at airfields.

 If you get lock for the first time while flying, your home will be set at the location of lock.

 If you set the ALT_HOLD_RTL to a number at other than 0 it will go to and maintain that altitude 

while returning.

 RTL uses the waypoint_speed to determine how fast it travels.
Page | 41

 Once the copter arrives at the home location the copter will enter Loiter mode, timeout 

(AUTO_LAND), and then land.

 To prevent auto-landing, simply change modes with the control switch to clear the landing timer 

and resume normal flight.

 The throttle stick controls the altitude while returning or loitering above home and not the 

motors directly.
Page | 42

Auto Mode

In autonomous (auto) mode, the copter will follow a pre-programmed mission script stored by the 

autopilot, including autonomously navigated waypoints, commands, and events. This pages provides 

information for using auto mode. For information on creating a mission script, visit the Planning a 

mission with waypoints and events page for detailed information on setting up a flight plan.

Overview

Auto mode allows the copter to follow internal mission scripting to control its actions. Mission scripts 

can be a set of waypoints or very complex actions such as, takeoff, spin X times, take a picture, etc.

Since mission scripts depend on the GPS for location information, auto mode is GPS dependent and it is 

necessary to allow the GPS to achieve lock before arming and taking off. Always ensure that the LEDs on 

the autopilot and GPS module indicate that GPS lock has been acquired:

 Blue LED on APM is solid.

 Blue LED on GPS module is solid.

 Blue LED on GPS+Compass module is blinking.
Page | 43

Warning: In Auto Mode the flight controller uses a barometer which measures air pressure as the 

primary means for determining altitude (“Pressure Altitude”) and if the air pressure is changing in your 

flight area, the copter will follow the air pressure change rather than actual altitude (unless you are 

within 20 feet of the ground and have SONAR installed and enabled).

Using Auto Mode from Ground and from the Air

There are two ways to enter auto mode: in the air or on the ground. If you are going to use auto mode 

to take off from the ground, a special safety prevents the execution of the mission script until you both 

arm and then raise the throttle for the first time. This is to prevent your copter from taking off on its 

own by accidentally flipping the mode switch. When using auto mode to takeoff from the ground, your 

most recent Alt_hold throttle value is used as a baseline for throttle control. Once the copter has taken 

off it will proceed to the first target altitude and to begin following the mission script.

Switching to auto mode when you are already in the air will cause your copter to go to your first target 

altitude and to begin following the current mission script.

Ending a Mission

Once the mission script is complete, the copter will not fly home, it will simply loiter at the last script 

location until you regain control through the mode switch. If you want your copter to fly home you can 

add an RTL command to the end of your mission script. If you want to land manually and disarm the 

motors (rather than auto land with a pre-programmed command), you must switch into stabilize mode 

to do so.

Remember that when using RTL, the copter will return to the home position (the location of the copter 

at the time of arming after the GPS is locked), so it is very important to arm your copter in the location 

you want it to return (unobstructed and away from people) when using auto mode. Warning: It is 

important to understand the home position always refers to the physical location where your copter 

was armed!

RTL or auto land at the last location in the mission script will force landing and disabling of the motors. 

Unless one of these two options is configured, you cannot land manually in auto mode, since the 

throttle stick controls altitude, not the motors directly.

Tuning

 The Waypoint_Speed value sets the rate of travel between waypoints.

 The default speed between waypoints is 6 meters per second by default.

 The NAV_PI is used to maintain the desired rate of travel for your copter between waypoints.

 NAV_P is used to tilt the copter to achieve the desired rate of speed, be it fast or no 

speed at all.

 The higher the P the more the copter will tilt.

 Nav_I is used to compensate for outside forces that would make your copter not 

maintain the desired rate.

 A high I term will ramp quickly to hold the desired rate, and will ramp down 

quickly to avoid overshoot.
Page | 44

Guided Mode

Guided mode is a capability of APM: Copter to dynamically guide the copter to a target location 

wirelessly using a telemetry radio module and ground station application. This page provides 

instructions for using guided mode.

Overview

Guided mode is not a traditional flight mode that would be assigned to a mode switch like other flight 

modes. The guided mode capability is enabled using a ground station application (such as Mission 

Planner) and telemetry radio (such as the 3DR Telemetry Radio). This capability allows you to 

interactively command the copter to travel to a target location by clicking on a point on the Mission 

Planner Flight Data map. Once the location is reached, the copter will hover at that location, waiting for 

the next target. Follow Me mode also uses Guided Mode to make the copter follow the pilot around the 

field.
Page | 45

What you’ll Need

To use guided mode, you’ll need a telemetry device like the 3DR Telemetry Kit 915mhz (US) or 433mhz 

(Europe) allowing your computer and autopilot to communicate during flight, a ground station computer 

or tablet, and a ground station application such as Mission Planner.

Instructions

 Set up your copter at the field and establish a MAVLink connection over wireless telemetry 

between your copter and your laptop.

 On your laptop, using the software that came with the telemetry module, make sure that it’s 

working and that you have a GPS lock.

 Take off in Stabilize mode and once at a reasonable altitude, switch to Loiter.

 In the Mission Planner Flight Data screen map, try right-clicking on a nearby spot and select “Fly 

to Here”.

 You will be asked for a guided mode altitude. Enter an above home altitude in meters.

 A “Guided” target should appear on the map and the orange line (which indicates the target 

heading) should point to this guided target.
Page | 46

 The vehicle should fly to the target location and wait there until you enter another location or 

switch to another mode.

Note: There’s no need to set up one of your flight modes as “Guided”
Page | 47

Board LEDs and Sounds

APM 2.5/2.6

LED Behavior:

Power On When Powered

A (Red)  Solid = armed, motors will spin when throttle is raised. 

 Single Blink = disarmed, motors will not spin.

 Double Blink = disarmed, motors will not spin, cannot arm because of failure in 

pre-arm checks

B (Yellow) Only flashes along with A and B during calibration or as part of the in-flight auto trim 

feature

C (Blue)  Solid = GPS working, 3D lock

 Blinking = GPS working, no 

 Lock-OFF = GPS not attached or not working

PPM/Serial Flashing when data detected

3DR GPS+Compass Module

The 3DR GPS+Compass module has two LED indicators: one for power (solid red) and one for GPS lock 

(flashing blue).

LEDs: Behavior:

Power Solid Red when powered

GPS lock Flashing Blue when 3D lock acquired
Page | 48

Pre-Arm Safety Checks(PASC)

APM: Copter 3.0.1 (and higher) includes a Pre-arm Safety Check which will prevent your Copter from 

arming if any of the following issues are present.

1. Verifies that Radio Calibration has been performed.

2. Verifies that Accelerometer Calibration has been performed.

3. Verifies that the Compass is Healthy and communicating properly.

4. Verifies that Compass Offsets are not too large: (greater than -150 and less than 150).

5. Verifies that the Compass Live or Log based calibration has been performed or that 

“COMPASS_LEARN” is on.

6. Verifies Adequate Compass Magnetic Field Strength: (APM 2 = about 330, APM1 = about 530, 

PX4 = about ?)

7. Verifies that the Barometer is Healthy and communicating properly.

8. If Geo-fencing is enabled the safety check verifies that you have GPS Lock before it will allow you 

to arm.

9. Verifies that the flight controller board Voltage is between 4.5 and 5.5 volts for APM 1 or APM 2 

(Disabled on PX4)

10. Verifies that Channel 7 and Channel 8 are Not set to control the same thing.

If everything else seems OK except that when you try to Arm with the throttle down and to the right, it 

will not actually arm and the motors will not spin, it has probably failed the Pre-Arm Safety Check. You

should also notice that the red arming light will double flash.

To See what has caused the PASC Failure

1. Connect your Flight Controller to Your Computer via the USB port.

2. Start Mission Planner and select the “Connect” button on the upper right of the page.

3. Turn on your radio transmitter and hold your throttle down and to the right (normal arming 

procedure).

4. The first cause of the Pre-Arm Safety Check failure will be displayed in red on the HUD window.

5. Address and correct each problem that is reported when you attempt to arm as above.

6. When all problems have been corrected, you will see verification of “Arming” in the HUD 

window.

7. You can then disconnect from your computer and have good assurance that arming will proceed 

normally.
Page | 49

Fixing Specific PASC Failures

1. If Radio Calibration check fails: Go to Mission Planner – Configuration – Radio Calibration.

a. And execute the Radio Calibration Procedure.

2. If Accelerometer Calibration check fails: Go to Mission Planner – Configuration – Ardu-Copter

Level.

a. Select your frame type and select the “Calibrate Accel” button and perform the leveling 

procedure.

3. If there is a Compass failure, you can go to Mission Planner – Configuration – Hardware Options 

– Compass.

a. And select the Live Calibration button.

4. Alternatively for a compass problem, Go to Mission Planner – Configuration – Advanced Params 

– Adv Param List.

a. Scroll down to the “COMPASS_LEARN” parameter, type in a 1 to enable it and select 

“Save Parameters”.

5. If the Barometer check fails: You have a hardware problem with the barometer or the flight 

controller board.

a. If the Geo-fencing without GPS Lock check fails, wait for your GPS to acquire lock before 

attempting to arm.

6. Or you can go to Mission Planner – Configuration – Geo-fencing and clear the Enable Geo-fence

box (turn it off).

a. If the battery voltage check fails, you are either supplying too high or too low a voltage 

to the APM board.

7. Or your peripherals that are being powered by the APM have too high a current draw.

a. It is very important to correct this problem and ensure you have between 4.5 and 5.5 

volts at your APM board.

8. If Channel 7 was set to the same thing as Channel 8, one of them must be set to another option.
Page | 50

Arming and Disarming the System

Arming the Motors

Before arming the motors, make sure all people and objects are clear of the propellers. Then do the 

following:

1. Turn on your transmitter

2. Plug in your LiPo battery. The red and blue lights should flash for a few seconds as the gyros are 

calibrated (do not move the copter)

3. If the red arming light is double blinking then the copter has failed the pre-arm checks. Please 

refer to this page.

4. Check that your flight mode switch is set to Stabilize or ACRO

5. If using a PX4, press the safety button until the light goes solid.

6. If you are planning on using the autopilot you should wait for 30 seconds after the blue GPS light 

has gone solid. This additional 30 seconds will give your GPS position time to settle.

7. Arm the motors by holding the throttle down, and rudder right for 5 seconds. It takes 

approximately 5 seconds the first time the copter is armed as it initializes the barometer. Do 

not hold the rudder right for too long (>15 seconds) or you will begin the AutoTrim feature.

8. Once armed, the red arming light should go solid.

9. Raise the throttle to take-off.

Note: you can only arm or disarm in Stabilize or ACRO mode

Note: if you leave the throttle at minimum for 30 seconds while in Stabilize or ACRO mode the motors 

will automatically disarm.

Disarming the Motors

To disarm the motors do the following:

1. Check that your flight mode switch is set to Stabilize or ACRO

2. Hold throttle at minimum and rudder to the left for 2 seconds

3. The red arming light should start flashing

4. If using a PX4, press the safety button until the led begins flashing

5. Disconnect the LiPo battery

6. Turn off your transmitter
Page | 51

Rate Roll and Pitch P Tuning

Although there are many gains that can be tuned in APM: Copter to get optimal performance but the 

most critical is the Rate Roll and Pitch P values. This page covers how to tune this gain during your 

maiden flight. This alone will likely get it flying reasonably well at least in Stabilize mode.

Rate Roll P and Rate Pitch P can be tuned in flight using your transmitter’s channel 6 tuning knob by 

following these instructions:

1. Connect your APM/PX4 to the Mission Planner

2. On the mission planner, select Software > Ardu-Copter Pids

3. Set the CH6 Opt to “Rate Roll/Pitch kP”

4. Set Min to 0.08, Max to 0.20 (most copters ideal gain is within this range although from a 

small number of copter the Max can be as high as 0.25)

5. Push the “Write Params” button

6. Turn your transmitter’s CH6 tuning knob to the minimum position, press the “Refresh 

Params” button and ensure that the Rate Roll P and Rate Pitch P values become 0.08 (or 

something very close)

7. Turn the CH6 knob to its maximum position, press “Refresh Params” and ensure the Rate 

Roll P moves to 0.20

8. Move the CH6 knob back to the middle

9. Arm and fly your copter in Stabilize mode adjusting the ch6 knob until you get a copter that 

is responsive but not wobbly

10. After the flight, disconnect your LiPo battery and reconnect the APM to the mission planner

11. With the CH6 knob in the position that gave the best performance, return to the ArduCopter Pids screen and push the “Refresh Params” button

12. In the Rate Roll P and Rate Pitch P fields re-type the value that you see but just slightly 

modified so that the mission planner recognizes that it’s changed and resends to the 

APM/PX4 (Note: if you re-type exactly the same number as what appears in Rate Roll P it 

won’t be updated). So for example if the Rate Roll P appears as “0.1213′′ make it “0.1200′′

13. Set Ch6 Opt back to “None” and push “Write Params”

14. Push the Disconnect button on the top right, and the Connect

15. Ensure that the Rate Roll P value is the value that you retyped in step #12
Page | 52

Note: while you are moving the tuning knob the values update at 3 times per second. The need to press 

the Refresh button in the mission planner in steps #6 and #7 above is just because the APM: Copter is 

not sending the updates to the mission planner in real-time.
Page | 53

Measuring Vibration

For good altitude hold and loiter performance it is important that your vibration levels are low. The 

instructions below will shows you how to measure the vibration levels. If you find they are out-oftolerance you should follow the advice found on the First Time Set-up sections Vibration.

Please follow these steps to ensure your vibration levels are within tolerance:

 Connect your APM/PX4 to the mission planner

 Go to the CONFIG/TUNING > Advanced Params screen and set the Log bitmask to Default+IMU.

This will enable the capture of the accelerometer data to the dataflash logs.

 Press the “Write Params” button

 Fly your copter in Stabilize mode and try to maintain a level hover (it doesn’t need to be 

perfectly stable or level)

 Disconnect the LiPo, reconnect your APM/PX4 to the mission planner

 Download the latest dataflash log using the Terminal 
Page | 54

 When the Log Browser appears, scroll down until you find any IMU message. Click on the row’s 

AccX and push “Graph this data Left” button. Repeat for the AccY and AccZ columns to produce 

a graph like below.

 Check the scale on the left and ensure that your vibration levels for the AccX and AccY are 

between -3 and +3. For AccZ the acceptable range is -15 to -5. If it is very close or over these 

limits you should refer back to the Vibration Dampening page for possible solutions.
Page | 55

 After all the above is complete, go back to the Mission Planner’s advanced parameters page 

(you may need to press the “Connect” button again) and set the Log Bitmask back to “Default”.

This is important because especially on the APM logging requires significant CPU resources and 

it’s a waste to log these if they’re not really needed.
Page | 56

Save Trim and Auto Trim

Wind of course has a strong effect on your copter and will push it around. However you may also find 

that while flying in stabilize mode, even in a windless environment your copter tends to always drift 

away in the same direction. This can largely be corrected using the “Save Trim” or “Automatic Trim” 

functions.

Save Trim

Save trim is the simpler method and involves essentially transferring your radio transmitter’s trims to 

the APM (video demo here).

1. Check that your CH7 switch goes above 1800 on the Mission Planner’s Hardware > Mandatory 

Hardware > Radio Calibration screen.

2. Set the CH7 Option to Save Trim on the Software > Ardu-Copter Pids screen and press the 

“Write Params” button.
Page | 57

3. With your CH7 switch in the off position, fly your copter in Stabilize mode and use your 

transmitters’ roll and pitch trim to get it flying level.

4. Land and put your throttle to zero

5. Release the roll and pitch sticks and switch the CH7 switch high for at least 1 second.

6. Reset your transmitters roll and pitch trims back to the center and fly again and it should fly 

level now. If it does not repeat steps 3, 4 & 5.

Auto Trim

With auto trim the roll and pitch trim are captured as you fly in a stable hover.

1. Find a wind free environment with sufficient space to fly your copter without crashing into 

something.

2. Hold throttle down and rudder right for 15seconds or until you see the small red, blue and 

yellow LEDs flash in a cyclic pattern.

3. Fly your copter for about 25 seconds in a stable hover

4. Land and put your throttle to zero and wait for a few seconds (the trims are being saved to 

eeprom)

5. Take off again in stabilize mode and check if your copter is flying level now. If not repeat steps 2, 

3 and 4.

Note: you can also test these procedures above are operational on the ground with your battery 

disconnected. Connect your APM to the mission planner and observing the Flight Data screen as you 

simulate completing the steps above.
Page | 58

Note2: you can manual set the trim through the mission planner’s Adv 

Parameters List page. Roll trim is AHRS_TRIM_X, Pitch trim is AHRS_TRIM_Y. 

Both values are in radians with left roll and forward pitch being negative 

numbers.

Note3: it’s nearly impossible to get rid of all drift so that your copter remains 

completely motionless without any input.
Page | 59

Flight Test Process

To Test Loiter and Altitude Hold:

1. Set up your APM so that Stabilize mode is at one extreme of your three-position mode 

select switch on your RC transmitter, Alt Hold mode is in the middle and Loiter mode is in 

the third position.

2. First, it ́s important that Stabilize Mode is working OK. Set the Mode switch to Stabilize, turn 

on the transmitter and connect your battery. Wait until the GPS gets a lock. (Both the Blue 

GPS LED and the Blue C LED on the APM should be on and solid before arming and taking 

off). (It is even better to wait a bit longer to allow the GPS acquire additional satellites.)

Note! The UBLOX GPS works differently

On the UBLOX GPS the LED on the GPS module is off during satellite acquisition and on with 

the blue LED blinking when the satellite is acquired.

3. Hold the throttle down and to the right for several seconds to “Arm” The motors on your 

copter.

4. Start flying in Stabilize mode. Make sure you can take off, fly comfortably, and land. If you 

find it tilting, land and run the “Level” command in the Mission Planner. Fly through a whole 

battery like this, getting a feel for the controls (this will also calibrate your compass).

5. Now change batteries and try the auto modes. First, try Alt Hold at an altitude of about 20 

meters. Your actual current throttle position is recorded as the “hovering point” when you 

switch to an altitude holding mode so it is important that you are not ascending or 

descending when you switch to Alt Hold. You should be able to fly around with the copter 

maintaining the same altitude, plus or minus a meter or so.

6. If that’s working well, try Loiter. Just fly to a safe spot with lots of room around it and an 

altitude of about 20 meters and switch into Loiter. It should try to stay in that position, plus 

or minus about five meters.

7. When you have finished flying in Loiter or Alt Hold modes (or if anything unexpected or 

undesirable happens) switch back to Stabilize mode and land. (You cannot land and turn the 

motors off in Loiter or Alt Hold mode.)

8. Disarm your copter and record a log by holding the throttle down and to the left for 5 

seconds.

What to Expect?

In Alt Hold, the copter should stay at the altitude you initiated the mode in, give or take about a meter. 

Adding sonar will improve that to +- 20cm accuracy up to 12 feet of altitude. (Above which sonar doesn’t 

work).

Warning: The flight controller uses a barometer which measures air pressure as the primary means for 

determining altitude (“Pressure Altitude”) and if the air pressure is changing in your flight area, the 

copter will follow the air pressure change rather than actual altitude.
Page | 60

In Loiter, the quad should stay in a 4-5 meter diameter “circle” around the target position. If there is 

wind, it may take a few seconds to compensate. If the wind is strong, you may see the control can’t 

compensate and you will have more error (ex 10-15 meters).

You can use the stick to move the quad manually in Loiter. Or you can use the throttle to raise or lower 

the quad.

 Warning: “Home” position is always supposed to be your Copters actual GPS takeoff location:

 It is very important to acquire GPS lock before arming in order for RTL, Loiter, Auto or any GPS 

dependent mode to work properly.

 For APM: Copter if you get GPS lock and then ARM your copter the home position is the location 

the copter was in when it was armed.

 This means if you execute an RTL in APM: Copter, it will return to the location where it was 

armed.

 For APM: Copter: Arm it where you want it to return to: (Not the Pits).
Page | 61

Advanced Configuration and Tuning

This section will take you through the more advanced configuration and tuning options for APM: Copter

Compass Set-up (Advanced) – all the compass set-up procedures explained

Fail-safe – protection for loss of radio contact, low battery, loss of GPS lock, loss of contact with the 

ground station

Fence – protection against fly-always

PPM Encoder information

 General information on the PPM Encoder

 Updating your APM’s PPM Encoder firmware – important if you purchase your APM before Mar 

2013

 Updating your APM’s PPM Encoder firmware (2) – same information as above

 Using the stand-alone PPM Encoder

Ch7 & Ch8 Auxiliary Functions – features that can be invoked from the Ch7 and Ch8 switches

Tuning – main tuning guide for APM: Copter

 Attitude Tuning (i.e. more details on Roll and Pitch Tuning)

 Altitude Hold Tuning

 Loiter and Navigation Tuning

APM: Copter parameters:

 Full parameter list

 Standard parameter list

Command Line Interface (CLI) – for those who don’t like graphical user interfaces

 CLI for radio and flight mode setup, test overview

 CLI for testing radio input

 CLI for dumping contents of eeprom

Testing your APM’s accelerometer and gyro sensors

Done all the above? Then you’re ready for Mission Planning and Analysis!
Page | 62

Compass Setup

This page covers all the possible compass set-up procedures in detail including some rarely used options.

Users must perform the first item (Live Calibration) and it’s strongly recommended that they perform 

the 2nd (Compassmot) as well to achieve good compass performance which is required for Loiter, RTL 

and AUTO flight modes.

If you after performing the above steps (and after trying to move your APM/PX4 further from source of 

compass interference) you still experience circling (also known as “toilet bowling”) in Loiter then you 

may wish to attempt the 3rd option (Tuning Declination In-Flight).

It is not recommended that users try the 4th (Automatic Learning of offsets during flight) and 5th (Log 

based calibration of offsets) options. The 6th item (Manually entering Declination) is also rarely 

significantly better than the automatically calculated declination.

Live Calibration of compass offsets

This is the default method for calculating offsets:

 Connect the APM to the mission planner

 Go to the hardware > Mandatory Hardware > Compass screen

 Push the “Live calibration” button

 When the screen below appears, select OK and you will have 60 sec. to complete the process.

 During the 60 sec. you should hold the copter in the air and rotate it slowly so that each side 

(front, back, left, right, top, and bottom) points down toward the earth for a few sec. in turn.
Page | 63

 A countdown will be displayed while it’s collecting data and, upon completion, the new offsets 

will be displayed. As long as all three values are between -150 and 150 the offsets are good.

Compassmot-compensation for interference from the PDB, ESC, or motors

This “Compassmot” set-up helps compensate for interference on the compass from the powerdistribution-board (and wires), ESC, motors and batteries. Please follow these instructions:

 Enable the 3DR power module or Non-3dr current monitor if present. If present this will allow 

more accurate compensation because the interference is linear with current drawn but not 

perfectly linear with throttle.

 Disconnect your props, flip them over and rotate them one position around the frame. In this 

configuration they should push the copter down into the ground when the throttle is raised

 Secure the copter (perhaps with tape) so that it does not move

 Turn on your transmitter

 Connect your vehicle’s LiPo battery

 Connect your APM/PX4 to your computer with the usb cable

 Open the mission planner’s terminal screen, press the “Connect APM” or “Connect PX4′′ button

 At the prompt type setup and then Compassmot.

 If you have a Power Module/Current monitor enabled you should see “measuring compass vs.

CURRENT” otherwise you will see “measuring compass vs. THROTTLE”
Page | 64

 You should hear your ESCs arming beep

 Raise the throttle slowly to between 50% ~ 75% (the props will spin!) for 5 ~ 10 seconds

 Quickly bring the throttle back down to zero

 Press enter to complete the calibration

 Check the % of interference displayed. If it is less than 30% then your compass interference is 

acceptable and you should see good Loiter, RTL and AUTO performance. If it is 31% ~ 60% then 

the interference is in the “grey zone” where it may be ok (some users are fine, some are not). If 

it is higher than 60% you should try moving your APM/PX further up and away from the sources 

of interference or consider purchasing an external compass or GPS+compass module.

Tuning Declination in-flight

Instead of using the automatic declination you can tune your declination value in flight using the 

Channel 6 tuning knob on your transmitter by following these steps:

1. Connect your APM/PX4 to the Mission Planner

2. Go to the Software > Ardu-Copter Pids screen

3. Set the Ch6 Opt to “Declination”, Min to “0.0′′ and Max to “3.0′′. This will give a tunable range 

of -30 to +30 degrees. Set Max to “2.0′′ to tune from -20 to +20 degrees, etc.

 Check that the declination is being tune correctly by turning the channel 6 tuning knob to its

maximum position, go to the Software >Adv Parameters List screen, press the “Refresh Params” 

button and ensuring that COMPASS_DEC is 0.523 (this is 30 degrees expressed in radians)
Page | 65

 Fly your copter in Loiter 

mode in at least two 

directions and ensure that 

after a fast forward flight 

you do not see any 

circling (also known as 

“toilet bowling”).

 If you find it’s impossible 

to tune away the circling 

then it’s likely your 

compass interference is 

will require an external 

compass or GPS+compass 

module.

Automatic learning of offsets during flight

APM: Copter (and Plane and Rover) include the ability to learn the offsets slowly during flight instead of 

performing the Live Calibration mentioned above. While this method works well on APM:-Plane it 

generally cannot deal with the high interference levels on many copters and has been known to slowly 

calculate extremely large offsets (less than -150 or greater than 150) which leads to incorrect heading 

and the copter flying off in the wrong direction in RTL, Loiter, AUTO.

It can be enabled by doing the following:

 Connect the APM/PX 

to the mission planner

 Go to Software > 

Advanced Params, 

scroll down to “Learn 

compass offsets 

automatically 

(COMPASS_LEARN)” 

and set it to “Enabled”

 Press the Write 

Params button

Log based calibration of offsets

This option is very close to the “Automatic learning” method (see above) except that a flight log is used 

instead of performing the calibration during an actual flight. This method suffers the same issue in 

which , due to high interference from the PDB, motors, etc the calculated offsets can be out of tolerance 

(i.e. less than -150 or greater than +150).
Page | 66

For this process you will need to fly the vehicle (any flight mode is acceptable) for at least a few minutes 

and most importantly the copter should be faced in all four directions (internally the algorithm divides 

the data up into 8 quadrants and it will fail if it doesn’t have any data from some quadrants)

The method can be done as 

follows:

 Connect the APM/PX4 to 

the mission planner

 Go to Hardware > 

Mandatory Hardware > 

Compass and click the 

“Log Calibration” button

 When the “Min 

Throttle” box pops up 

leave the number as the 

default 30

 If a message pops up 

saying “Log does not 

contain enough data” you will need to find another log in which you’ve flown longer and have 

flown the copter in more directions

 If the process completes successfully a “New Mag Offsets” box will pop-up with the new 

calculated offsets. As long as these are greater than -150 and less than +150 it has likely done a 

good job.

Manually entering declination

By default APM: Copter will look up the declination in a compressed table when it first achieves GPS 

lock. In generally this method is accurate to within 1 degree but if you wish to use the uncompressed 

declination value you can do this:

 Open the Declination Website.

 It should automatically figure out your location based on you IP 

address or you can enter your location

 Uncheck the Auto Dec checkbox and manually enter the 

declination (highlighted in red in the image above) into the 

mission planner’s declination field. In this example, we would 

enter “14.13′′ into the magnetometer line

 As soon as your cursor exits the field (i.e by pressing Tab) the 

value will be converted to decimal and saved to the eeprom
Page | 67
Page | 68

Fail-safes

As of version 3.0, APM: Copter has four fail-safe : Throttle, Battery, GPS and Ground Station Control.

Only the GPS failsafe is enabled by default.

Throttle Fail-safe

If enabled and set-up correctly the throttle failsafe will trigger if:

 Your copter goes out of radio range.

 You turn off your transmitter.

 Your receiver loses power for some reason.

 The channel 3 signal wire from your receiver to your APM’s input becomes disconnected.

Note: This behavior depends upon the version of your ppm encoder. Instructions for updating 

your ppm encoder firmware are here for APM2.X.

 The APM’s PPM encoder fails to send updates for 2 seconds (very unlikely). The PPM encoder is 

a small chip on the APM boards whose sole function is to read the radio signals from the 

receiver and send them to the APM’s main CPU.

When a throttle failsafe is triggered one of the following will happen:

 Disarm motors – if you are in stabilize or acro mode and your throttle is zero

 RTL – if you have a GPS lock and are at least 2 meters from your home position

 LAND – if you have no GPS lock or are within 2 meters of home when the failsafe triggers
Page | 69

 Continue with the mission – if you are in AUTO mode and have set the Failsafe Options to 

“Enabled_continue_in_auto_mode”.

 If the failsafe clears (throttle climbs back above 975) the copter will remain in its current flight 

mode. It will not automatically return to the flight mode that was active before the failsafe was 

triggered. This means that if, for example, you are flying in stabilize mode when the failsafe is 

triggered, and this causes the flight mode to change to RTL or LAND, if you wish to re-take 

control of the copter you will need to change your flight mode switch to another position and 

then back again to Stabilize.

Throttle Fail-Safe Setup

Receiver set-up:

 Each brand of Transmitter/Receiver has a slightly different method of setting up its failsafe but 

all but the very cheapest brands allow you to set the levels that you want some or all of the 

channels to move to when the transmitter and receiver (tx/rx) lose contact. Please refer to your 

transmitter’s user manual for details on how to enable the failsafe. Below are links for specific 

transmitters/receivers:

 Futaba T7C TX with R617FS or TFR4-B receiver

 You must set-up the throttle channel (channel 3) to move below its normal range (ideally below 

975) when the transmitter is turned off and ideally all other channels should remain at their last 

position or move to the middle

 To see what level your throttle channel becomes when the tx/rx lose connect your APM to the 

Mission Planner and check the levels on the Software > Failsafe page.

APM Setup

With the LiPo battery disconnected, connect your APM to the mission planner and select Software > 

Failsafe.

Set the Failsafe Options to “Enabled_always_RTL” or “Enabled_continue_in_auto_mode” if you expect 

to do auto missions that will take your copter beyond tx/rx range (which is generally not recommended).

Adjust the FS Pwm field to be:

 at least 10 pwm higher 

than your Channel 3′s 

pwm value when your 

transmitter is off

 at least 10 lower than 

your channel 3′s pwm 

value when your 

transmitter is on

 above 910
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Testing for correct operation of Throttle Fail-safe

You can check your failsafe by performing the following tests with the APM connected to your mission 

planner either via a USB cable or telemetry link. You can complete these tests without plugging in your 

LiPo battery but if you do connect a battery you should first remove the propellers.

Test #1 : ensuring that your throttle channel drops with loss of radio contact

1. Ensure your RC transmitter is on and connected with the throttle all the way down and flight 

mode set to Stabilize

2. The throttle (channel 3) pwm value should be approximately as in first illustration below. It’s 

value may be higher or lower but it should definitely be at least 10 higher than the value held in 

the FS Pwm field

3. Turn the transmitter off and the throttle pwm value should drop to be at least 10 below the FS 

Pwm field value (as in the second illustration below) below
Page | 71

Test #2 : ensuring motors disarm if in stabilize or acro with throttle at zero

 Switch to stabilize mode, arm your motors but keep your throttle at zero. Turn off your 

transmitter. The motors should disarm immediately (red led will start flashing, DISARMED will 

be displayed in the Mission Planner’s Flight Data screen).

Test #3 : ensuring flight mode changes to RTL or LAND when throttle is above zero

 Switch to stabilize mode, arm your motors and raise your throttle to the midpoint. Turn off your 

transmitter. The Flight Mode should switch to RTL if you have a GPS lock or LAND if you do not 

have a GPS lock (the flight mode and GPS lock status are visible in the Mission Planner’s flight 

data screen).

Test #4 : retaking control after a throttle failsafe event

 continuing on from test #3, turn your transmitter back on

 While the flight mode is still in RTL or LAND and armed, change the flight mode switch to 

another position and then back to stabilize mode. Ensure that the flight mode displayed on the 

Failsafe page is updating appropriately.

Test #5 (optional) : removing power from the receiver

 Switch to stabilize mode, arm your motors and keep your throttle above zero.

 carefully disconnect the power wires connecting the receiver to the APM

 the Flight Mode should switch to RTL or LAND as described in Test #3

 Warning: unplug the APM so that it is powered down before reattaching the receiver’s power

Warning to FRSky receiver users and users of other receivers that modify channel 5 during a failsafe 

event

Some FRSky tx/rx systems receivers can only be set-up to modify all channels including the flight mode 

channel (channel 5) when a failsafe event occurs. For these receivers it is important to setup the 

receiver’s channel 5 failsafe value so that the APM is switched into RTL, Loiter or LAND. This is critical 

because there is a very short period of time (3/50ths of a second) between when the receiver pulls the 

throttle low and when the APM initiates the RTL or LAND. During this time, if the receiver also switches 

the flight mode channel to stabilize or acro the APM may switch to stabilize momentarily and then 

because the copter is in stabilize with throttle at zero it will disarm the copter (i.e. Test #2).

Battery Fail-safe

 If enabled and set-up correctly the battery failsafe will trigger if:

 your battery voltage becomes low for more than 10 seconds

 your estimated current consumed passes your battery capacity (set on the power 

module set-up page)

 When a battery failsafe is triggered one of the following will happen:

 Disarm motors – if you are in stabilize or acro mode and your throttle is zero
Page | 72

 RTL – if you are in AUTO mode, have a GPS lock and are at least 2 meters from your 

home position

 LAND – in all other cases

 Setting up the battery failsafe

 first set-up the power module as described here including setting the Battery Capacity if 

using a current monitor

 On the INITIAL SETUP > Mandatory Hardware > Failsafe page click the Battery Failsafe 

checkbox and enter the Low Battery level that you wish to have trigger an RTL or LAND.

GPS Fail-safe

 The GPS Failsafe is enabled by default but you can enable or disable it on the Mission Planner’s 

Advanced Parameter List, by set the FS_GPS_ENABLE parameter to 0 (disable) or 1 (enable).

 If you lose GPS contact for 5 seconds while you are in AUTO, GUIDED, LOITER, RTL, CIRCLE or 

POSITION mode it will initiate a LAND.

Ground Control Station Failsafe

 In Mission Planner’s Advanced Parameter List, set the FS_GCS_ENABLE parameter to:

 0 to disable the GCS failsafe

 1 to enable and always RTL in event of loss of contact

 2 to RTL unless in AUTO mode in which case we should continue with the 

mission

 If you have been using the ground station to control the copter (i.e. using a joystick) and then 

lose Ground Control Station contact for at least 5 seconds the following will happen:

 Disarm motors – if you are in stabilize or acro mode and your throttle is zero

 RTL – if you have a GPS lock and are more than 2 meters from your home position
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 LAND – if you have no GPS lock or are within 2 meters of home

 Continue with the mission – if you are in AUTO mode and have set the GCS Failsafe 

Options to 2 (Enabled_continue_in_auto_mode).

 If the failsafe clears (contact with the ground station is restored) the copter will remain in its

current flight mode. It will not automatically return to the flight mode that was active before the 

failsafe was triggered. This means that if, for example, you are flying in stabilize mode when the 

failsafe is triggered, and this causes the flight mode to change to RTL or LAND, if you wish to retake control of the copter you will need to set your flight mode again back to stabilize.
Page | 74

Geo-Fencing

Overview

AC 3.0.1 (and higher) include a simple “tin can” shaped fence centered on home that will attempt to 

stop your copter from flying too far away by initiating an RTL. The maximum circular distance and 

altitude and the vehicle behavior when the fence is reached can be configured using Mission Planner.

If the vehicle strays outside these borders it will switch into RTL or LAND. At the moment the fence is 

breached a backup fence is erected 20m further out (or up). If the copter breaches this backup fence 

(for example if the the vehicle is not set up correctly or the operator takes control but is unable to bring 

the copter back towards home) the copter will be switched into RTL again (and another backup fence an 

additional 20m further out will be created).

If the copter eventually flies 100m outside the configured fence distance, the vehicle will switch into 

LAND mode. The idea being that it’s clearly impossible to get the copter home so best to just bring it 

down. The pilot can still retake control of course with the flight mode switches. Like with the earlier 

fences, another fence is erected 20m out which will again switch the copter to LAND if it continues away 

from home.
Page | 75

Enabling the Fence in Mission Planner

The Fence can be set-up by doing the following:

 Connect your APM/PX4 to the Mission Planner

 Go to the Software -> GeoFence screen

 Click the “Enable” button

 Leave the “Type” as “Altitude and Circle” (unless you want only an Altitude limit or only a 

Circular fence in which case you can select “Altitude” or “Circle”)

 Leave the Action as “RTL or Land”

 Set “Max Alt” to the altitude limit you want (in meters)

 Set “Max Radius” to the maximum distance from home you want (in meters). This should 

normally be at least 50m

Enabling the fence with Channel 7 or 8

It is not necessary to set-up a switch to enable or disable the fence but if you wish to control the fence 

with a switch please follow these steps:

 Go to the Mission Planner’s Software > Ardu-Copter Pids screen and set either “Ch7 Opt” OR 

“Ch8 Opt” to Fence.

 Holding the switch high (i.e. PWM > 1800) will enable the fence; low (less than 1800) will 

disable the fence.
Page | 76

Warnings:

 The minimum recommended fence radius is 30m

 For the best results, ensure RTL is working on your vehicle.

 With the Fence enabled, the pre-arm checks will require you have GPS lock before arming 

the vehicle.

 If GPS failsafe is not enabled and the Fence is enabled and you lose GPS lock while flying the

fence will be disabled.

 If GPS failsafe is enabled and the Fence is enabled and you lose GPS lock while flying the 

vehicle will switch to LAND because we no longer know the vehicle position and we want to 

ensure the copter never travels far outside the fence. This behavior will occur regardless of 

the flight mode. If a LAND sequence is not desired, the pilot can retake control by moving 

the flight mode switch.

 The backup fences are created 20m out from the previous breached fence not 20m out from 

the vehicle’s position. This means if you choose to override the fence you may have less 

than 20m to regain vehicle control before the fence switches the copter to RTL (or LAND) 

again. If you really want to override the fence, you should be ready to switch the flight 

mode twice or alternatively set-up the enable/disable fence switch.
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Setting Channel 6, 7, or 8 options

By default, Channel 7 is configured to save the current location as a waypoint (see “Save WP” below) but 

you can change the default behavior from the Mission Planner’s Software > Ardu Copter Pids screen.
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Here are the options:

Option Description

Flip Vehicle will flip is on roll axis. Vehicle will rise for 1 second and then rapidly 

roll. The vehicle will not flip again until the switch is brought low and back to 

high. Give yourself at least 10m of altitude before trying flip for the first time!

Simple Mode The copter moves left, right, forward and back as if it were facing in the same 

direction as when it took off regardless of the copter’s heading.

RTL Return-to-Launch. The vehicle will first climb to a safe altitude (defined by 

RTL_ALT parameter), then return home, pause over home for 5 seconds 

(configurable by RTL_LOIT_TIME parameter) then descend to 2m or land 

(configurable by RTL_ALT_FINAL parameter).

Save Trim Adjust the vehicle level position using the current roll and pitch stick inputs. See 

details.

Save WP Save the current location (including altitude) as a waypoint in the mission. If in 

AUTO mode no waypoint will be saved, instead the vehicle will RTL

Multi Mode Ch6 tuning knob position controls which of the following 3 functions is invoked 

when ch7 or ch8 switch put in the on position.

 Ch6 <1200 : Flip

 Ch6 1201 ~ 1799 : RTL

 Ch6 > 1800 : Save Waypoint

Camera Trigger Camera shutter will be activated. See more details

Sonar Sonar is disabled when switch is in low position, enabled when it high position.

Fence Fence is disabled when switch is in low position, enabled when it high position.

Reset to Armed Yaw Vehicle will turn to face the same direction that it was facing when it was first 

armed (e.g. at take-off). An alternative to simple mode when you’ve lost 

orientation and need to bring the craft home.

Super Simple Mode Similar to simple mode except controls are relative home position. Move the 

pitch stick forward and the copter will fly away from home, pull pitch back and 

it will return. Move roll stick left or right and the copter to orbit home 

regardless of the copter’s actual heading.

Check Ch7 & Ch8 PWM values reach 1800

Your channel 7 and/or channel 8 

pwm values must reach at least 

1800 PWM or the auxiliary 

function will not be activated.

You can check that it surpasses 

this threshold using the Mission 

Planner’s radio configuration

page.
Page | 79

Tuning

If you’re using an airframe other than the 3DR Copter kit, you may need to change some PID settings 

(PID stands for Proportional-Integral-Derivative and is a standard control method)

You can adjust PIDs interactively in the Mission Planner’s Configuration tab. Start with the APM: Copter 

PIDs page, which breaks out the most important settings and gives instructions on how to use them. 

More configuration settings can be found in the Standard Params and Advanced Params if you need 

them (you probably won’t).
Page | 80

Basic performance troubleshooting

Remember two things:

 Start by using Stabilize Mode for tuning, if it doesn’t fly correctly in Stabilize it will NOT

fly correctly in any of the other modes.

 First use the defaults. You shouldn’t have to deviate very far from the defaults that are 

loaded with the firmware, if you have to change them then use small increments and one at 

a time. If you have to use a value that is very different then either something else is wrong 

or your ‘copter is very different from everyone else’s.

For normal flight, there is really only one term you should care about and that is the

Rate Roll P setting

(Rate Pitch is normally slaved to that, as the checkbox on the screen above shows). Use the in-flight 

tuning method with CH6 to nail this term in a few seconds. Make it as aggressive as you can before it 

begins to oscillate. You will have great performance descending straight down if this term is higher. You 

may want to tune it down a hair more if you like a softer response.

Here’s an example: the default setting for Rate Roll P is 0.14. This is optimized for the standard 

Jdrones/3DR quad copter with 850 motors and a 10′′ prop. If, however, you’re using the bigger 880 

motors and a 12′′ prop, which are much more powerful, that Rate Roll P will be too aggressive and your 

quad will seem quite unstable. So in that case, lower your Rate Roll P to 0.1 or 0.09, and you should see 

much more stable flight.

The same is true for Altitude hold. Throttle Rate P needs to be adjusted to get optimum altitude 

performance.

These two terms go a long way to making your copter perform well, and are highly dependent on the 

thrust to weight ratio of your copter. More thrust = lower gains.

 My copter oscillates quickly (smaller movements) when stabilized: Lower your gain in Rate 

Control P.

 My copter oscillates slowly (larger movements) when stabilized: Lower your gain in 

Stabilize Control P.

 My copter gets wobbly when descending quickly: Raise your gain in Rate Control P. You can 

tune most of this out, but it’s impossible to descend into your prop wash without some 

wobbles.

 My copter is too sluggish : Raise your Stabilize Control P gain. These gains make ask the 

copter to respond faster to angle errors.

 My copter yaws right or left 15° when I take off: Your Motors are not straight or your ESCs 

are not calibrated. Twist the motors until they are straight. Run the ESC calibration routine.

 My copter angles back in the opposite direction I’m flying after forward flight: Raise your 

gain in Stabilize Control P.
Page | 81

 After aggressive flying my copter leans to one side 10 – 30°: Do whatever you can to 

remove vibrations and isolate APM. You can even try and add a small weight to APM to keep 

it from vibrating. Also, just land for a few seconds, then continue flying, it will give APM a 

chance to correct without the vibration.

 My copter won’t stay perfectly still in the air: Run the level command on a flat surface. 

(hold disarm for 15 seconds to invoke.) You can also fly in auto-trim mode in a windless 

(important!) environment. Any wind will cause the changes you make to work against you 

when the quad rotates 180°. You can use your radio pitch and roll trims, but remember to 

re-center them when you set up your radio with the config tools. Using the radio trims can 

have a negative effect in SIMPLE mode when yawing. Never Trim Yaw, Your copter may start 

spinning on its own. (Quads are also susceptible to drafts. They will need constant 

corrections unless you install an optical flow sensor. One day...)

 My copter flies well, but then dips a motor arm in a fidgety manner while hovering: Your 

motor may be going bad or the bullets connectors between the motor and ESC may be at 

fault. Vibration from a bent shaft or unbalanced props can make bullet connections fail 

momentarily stopping the motor. A motor with bad bearings takes more power to spin. The 

ESC could be cutting out to protect itself. Or it may be flying slow enough to stall the motor. 

Attach a current sensor between your battery and the motor and test the difference 

between a good motor and the bad one. If you are seeing higher draw in the bad one, 

replace or fix it.

 My copter suddenly crashed for no good reason: The I2C port, used to talk to the compass, 

has a rare but very serious flaw which will block code execution To avoid any issues be sure 

to solder the compass securely.

 In Loiter, my copter constantly overshoots: Try and increase your Nav_P term. You can also 

tune down your I terms because in some cases, the Nav_I or Loiter_I can causes overshoot. 

Making the I terms 0 when in still wind is the best way to tune Nav_P.

 My alt hold above 10 feet is only about 1-2m accurate: That’s actually the best you can 

achieve. The baro sensor is sensitive to light and wind. Use a felt cover to protect it from 

wind and make sure you don’t glue the hole and seal it up.

 My copter increasingly swings up and down in alt hold. It eventually gets down to the 

ground: Your THROTTLE_P is too high or low. You don’t need a lot of P to do alt hold. Think 

of how much you move the throttle to hold alt perfectly. Not much! That’s what you need P 

to do. I will ramp up as your battery goes lower to make up the difference.

 I have a sonar installed but I can’t get it to work. Your sonar may be picking up electrical 

noise from the ESCs. Be sure to move it a few inches from any ESCs and try a shielded cable, 

if possible. If it’s cold outside, your sonar may stop working.

 My quad loiters by rotating in a CW or CCW circle: Adjust your compass declination until it 

stops circling.
Page | 82

In-flight tuning

You can tweak parameters in flight from Mission planner (needs a telemetry link or USB cable) or with 

the Transmitter (Tx) channel 6 knob or lever (You need an extra free channel that is controlled by a knob 

or slider on your transmitter(Tx) to use the CH6 fine-tuning function, you can use any free channel on 

your Tx but it must be plugged in to the CH6 option on APM. So CHx on Tx > CH6 position on APM.)

Method 1:

(See also Method 2: Flying Attitude Tuning below)

Select the “APM: Copter Configuration” tab in the Mission Planner, choose the CH6 option you’d like to 

tune. e.g. CH6_RATE_KP.

From MP v1.1.44 onwards these high and low values can be adjusted in boxes just below the CH6 

options. Alternatively you can also adjust TUNE_HIGH and TUNE_LOW in the left hand pane of the 

Configuration > Adv Parameter List.

Input the high and low limit of the parameter you’d like to tune, choose a value of + and – around 30-

40% of default, (so for CH6_RATE_KP set ‘low’ to 0.100 and ‘high’ to 0.180 from the default of 0.140)

Then click ‘Write Params’. To check the values click ‘Refresh Params’, your high and low values should be 

correct in both the Parameter List tab (under TUNE_HIGH & TUNE_LOW) and in the adjustment boxes. If 

not enter them again.

To test that the values are changing: move the lever or knob then click ‘Refresh Params’, the value 

should be displayed in the center pane in the respective box, move it again and click ‘Refresh Params’ 

again, the value should’ve changed. Alternatively select the Terminal tab, type ‘test’ and then ‘tune’ and 

your value will scroll down in the window, adjust the knob or lever to see the values change.

Now set your CH6 knob or lever to between 0 and 25% on your transmitter, then carefully test fly, land 

and tune the parameter with the knob or lever, test fly again.

To read your final parameter, leave the knob or lever on your Tx in your chosen position, connect to the 

MP then click ‘Refresh Params’, the value should be displayed in the in the respective box in the 

Parameter List tab (under TUNE_HIGH & TUNE_LOW). Alternatively select the Terminal tab again, type 

‘test’ and then ‘tune’ and your value will scroll down in the window. Enter this value into the correct 

position in the Configuration tab.

Now tune another parameter or, if you’re finished, set the parameter to CH6_NONE (important!)
Page | 83

The main value to tune is your Rate_KP value. This value adjusts whether your copter is:

 no response to control inputs (too low)

 sluggish (a little too low)

 stable (just right)

 over-active (a little too high)

 or oscillating (too high)

Here are all the parameters one can tune:

CH6_NONE 0

—Attitude

CH6_STABILIZE_KP 1

CH6_STABILIZE_KI 2

CH6_STABILIZE_KD 29 // duplicate with CH6_DAMP

CH6_YAW_KP 3

CH6_YAW_KI 24

—Rate

CH6_ACRO_KP 25

CH6_RATE_KP 4

CH6_RATE_KI 5

CH6_RATE_KD 21

CH6_YAW_RATE_KP 6

CH6_YAW_RATE_KD 26

—Altitude rate controller

CH6_THROTTLE_KP 7

—Extras

CH6_TOP_BOTTOM_RATIO 8

CH6_RELAY 9

—Navigation

CH6_TRAVERSE_SPEED 10 // maximum speed to next way point

CH6_NAV_KP 11

CH6_LOITER_KP 12

CH6_LOITER_KI 27

—Trad Heli specific

CH6_HELI_EXTERNAL_GYRO 13

—altitude controller

CH6_THR_HOLD_KP 14

CH6_Z_GAIN 15

CH6_DAMP 16 // duplicate with CH6_YAW_RATE_KD

—optical flow controller

CH6_OPTFLOW_KP 17
Page | 84

CH6_OPTFLOW_KI 18

CH6_OPTFLOW_KD 19

CH6_NAV_I 20

CH6_LOITER_RATE_KP 22

CH6_LOITER_RATE_KI 28

CH6_LOITER_RATE_KD 23

CH6_AHRS_YAW_KP 30

Method 2: Flying Attitude Tuning with CH6:

In this case you will tune your ‘copter while it is actually flying.

This assumes that the ‘copter is fairly flyable/controllable and that the pilot is experienced enough to 

easily keep the ‘copter at eye level and in the same place for at least 60 secs. You will also preferably 

need an open space of perhaps 10mx10m (30ftx30ft).

Follow the setup in Method 1 above.

Do Rate_P first, choose a value of + and – around 30%-40% of default, (so for Rate_P set ‘low’ to 0.100 

and ‘high’ to 0.180 from the default of 0.140. Be careful not to set these values incorrectly – don’t set 

0.100 as 1.000 or 0.010!

Hover at about 1.5m (5ft) and bank the quad briefly left and right, then either land and turn the 

knob/lever that controls the channel, or if you can fly and turn the knob/lever then do so, turn it up and 

down, note the difference and choose the flying style which “feels” best to you. Higher values might 

cause oscillations so back off a little until it flies without oscillations but isn’t too sluggish.

To read your final parameter, leave the knob or lever on your Tx in your chosen position, connect to the 

MP then click ‘Refresh Params’, the value should be displayed in the in the respective box in the 

Parameter List tab (under TUNE_HIGH & TUNE_LOW). Alternatively select the Terminal tab again, type 

‘test’ and then ‘tune’ and your value will scroll down in the window. Enter this value into the correct 

position in the Configuration tab.

Now tune another parameter or, if you’re finished, set the parameter to CH6_NONE (important!)

Note: (Set I values generally low, eg 0.000-0.100.)

Interactive PID demos

You can play with these Flash demos to get a feel for how PIDs work. Just click on the arrows to change 

the values, or type in new ones. Click in the background of the left demo to have it read your space bar. 

In the Demo Stabilize P is out of date. We call it Rate_P now.
Page | 85

Attitude PID Tuning

The attitude of the copter is controlled by a nested PI->PID loop. Tuning the inner PID loop is essential to 

good stable flight. The outer PI loop is less sensitive and effects mostly the style of flying desired (fast or 

slow).

Overview

The inner PID loop looks at the desired rate 

of angular rotation and compares that to 

the raw gyro output. The difference is feed 

back into the PID controller and sent to the 

motors to correct the rotation. This is the 

heart of both Rate(Acro) mode, Stabilize 

mode, and all other modes. It is also the 

most critical gain to adjust for your copter.

The outer PI loop generates the desired rate 

of angular rotation. The input for this loop 

can either be user with stick movement, or 

the stabilizer, which tries to achieve a 

specific angle.

To get a better idea of the flow of command 

to motor output, here is a diagram of the 

Roll control.

PID Rate Tuning

Parameter: RATE_RLL_P and RATE_PIT_P 

are the proportional response and the 

default is 0.14. Your copter will vary quite a 

bit depending on the weight and thrust of 

your engines. If your copter oscillates 

rapidly, lower this value. If it is sluggish, raise the value. This is the

#1 parameter

that needs tuning. If it is not right, every other parameter is a waste of time.

Parameter: RATE_RLL_I and RATE_PIT_I are set to 0 by default. Use this value to maintain tight control 

of the speed of rotation the copter. If the copter is not achieving the rotation rate needed to hold a tight 

attitude, this term will make up the difference.

Parameter: RATE_RLL_D and RATE_PIT_D is .0025 by default. This value will dampen the acceleration 

towards the target angle. It If the value is too high you will see small, fast oscillations in pitch or roll. You 

may even temporarily lose control of pitch or roll as the D term saturates the control output.
Page | 86

Parameter: STAB_D is .06 by default. This dampens the acceleration of rotation of the copter and can 

eliminate those small wobbles after a set point change (a quick angle change). This is similar to 

RATE_RLL_D but only dampens acceleration. STAB_D is similar to RATE_RLL_D, but it’s unfiltered (faster) 

and has inherently less noise than RATE_RLL_D. Just as the RATE_RLL_D, a large value may cause 

oscillations or temporarily loss of control of pitch or roll as the D term saturates the control output.

Note: When tuning your copter, set RATE_I and RATE_D to zero, and only tune RATE_P. Once you have 

that dialed in, then tune RATE_I and RATE_D.

PI Control Tuning

Parameter: STB_RLL_P and STB_RLL_P is by default 4.5 or 4.5° per second rotation for every 1° of error. 

If you want more or less speed of rotation based on user input, adjust this value. A larger Octo may want 

to have a smaller number, 3.5 perhaps, or you will get a large seesaw style oscillation.

Parameter: STB_RLL_I and STB_PIT_I are used to overcome imbalance in the copter. If the copter is not 

symmetrical this I term will bring the copter to level. The higher the number the faster the copter will 

compensate. Low numbers can have adverse effects by causing a very slow oscillation measured in 

seconds. If you use this term, consider potential conflicts in timing with Rate_I. It may be best to keep 

one or the other zero.
Page | 87

Altitude Hold Tuning

Altitude Hold uses a throttle value as the center point for all throttle adjustments. A simple averaging 

filter looks at the climb_rate and determines this value during stabilization. This value will change during 

the course of the flight because of voltage drop off.

PI Control

The altitude error is calculated in centimeters and fed to the controller. The first stage of the controller 

takes the altitude error and decides how fast the copter should go to reach the correct altitude.

Parameter: THR_ALT_P is by default .4 or 40 cm/s for a 1m error. The desired rate maxes out at 1m/s.

Parameter: THR_ALT_I is used to close the gap between the actual hover throttle and current assumed 

hover throttle. For example, if your copter hovers at 52% throttle, and your set point is 4% your copter 

will fall until it reaches equilibrium with THR_ALT_P times the error. This is called a steady state error, 

and leaves your copter too high or too low. THR_ALT_I will increase to effectively raise the throttle to 

52%. The higher the number the faster it happens. If your number is too high it will cause oscillations.

PID Rate Control

Now that we have a desired rate, we need to change the thrust to give us that rate.

Parameter: THR_RATE_P is the proportional response and the default is .35. Your copter will vary quite a 

bit depending on the weight and thrust of your motors. If your copter oscillates up and down in alt hold, 

lower this value.

Parameter: THR_RATE_I is set to 0 by default. It should, in theory, fix issues with a bad THR_RATE_P 

value, but it’s best to just get that tuned well in the first place.

Parameter: THR_RATE_D is 0.02 by default, but the noise of the Baro sensor can cause issues. If the 

value is too high you will see bad oscillations or pulsing of the motors. Once the THR_RATE_P value is 

dialed in, start at 0, and increment slowly. You should see oscillations die down.
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Loiter and Navigation Tuning

Loiter and navigation use the same PID rate controllers.

The location error is calculated in centimeters for X (Longitude) and Y(Latitude) which is fed to the 

controller. The first stage of the controller takes the XY position error and decides how fast the copter 

should go to reach the correct location.

PI Control

Parameter: HLD_LAT_P and HLD_LON_P is by default .4 or 40 cm/s for a 1m error. The desired rate 

maxes out at 150cm/s. This doesn’t limit the pitch of the copter, The rate controller will do what it takes 

to maintain this speed as it approaches the location.

Parameter: HLD_LAT_I and HLD_LON_I are used to overcome wind that may be pushing us away from 

our target. The higher the number the faster the copter will compensate. If your number is too high it 

will cause oscillations and overshoot.

PID Rate Control

Now that we have a desired rate, we need to change the copter pitch and roll to give us that rate of 

travel.

Parameter: LOITER_LAT_P and LOITER_LON_P are the proportional response and the default is 2.2. Your 

copter will vary quite a bit depending on the weight and thrust of your engines. If your copter 

overshoots the target, lower this value.

Parameter: LOITER_LAT_I is set to 0 by default. Use this value to maintain tight control of the speed of 

the copter. If the copter is not achieving the speed it needs, this term will make up the difference by 

tilting the copter more or less.

Parameter: LOITER_LAT_D is 0.015 by default, but the effect is not well tested. If the value is too high 

you will see small oscillations in pitch or roll. Once the LOITER_LAT_P value is dialed in, start at 0, and 

increment slowly. You should see oscillations die down.
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Sensor Testing

Connecting to Mission Planner

 Start Mission Planner and hook up your APM or PX4 board via the USB port.

 Ensure that the correct COM port for your APM or PX4 is selected and click on the 

“Connect” button on the right.

 With MAVlink connected, move the APM board and you should see the “Artificial Horizon” 

in the HUD move accordingly.

 In an artificial horizon, when the aircraft tilts to the right, the horizon tilts to the left. (Just 

tilt your head and you can visualize this). This is normal! Please don’t tell us it’s reversed ;-)

 In the below example, the quad is tilted a bit to the right.

 Unless you have the GPS module connected, are outside and have GPS lock, the map will not 

show your current position.

You can see the output from all the various sensors by clicking on the “Tuning” checkbox on the bottom 

right of the display 1 this will bring up the graphical sensor display.

If you click on the legend at the top of it 2 , it will bring up a window “Graph This” that allows you to 

choose which sensors and data outputs to display.
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Mission Planning and Analysis

Here are some of the features of Michael Oborne’s Mission Planner:

 Point-and-click waypoint entry, using Google Maps.

 Full ground station for monitoring missions and sending in-flight commands.

 Select mission commands from drop-down menus

 See sensor output and test autopilot performance

 Download mission log files and analyze them

 Configure APM settings for your airframe

 See the output from APM’s serial terminal

Planning a Mission with Waypoints and Events

In Mission Planner you can create missions use the easy point-and-click Waypoint Editor created by 

Michael Oborne.

Note: Although this uses APM: Copter as the main example the primary methods apply for APM:

Plane and APM: Rover although altitude control is severely limited in APM: Rover.

It is very important to acquire GPS lock before arming in order for RTL, Loiter, Auto or any GPS 

dependent mode to work properly.
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Basic Waypoint Commands

A mission file is a little intimidating to the human eye, but is a powerful scripting language for the 

autopilot. (Again, remember that the GCS will soon take care of all of this for you. You shouldn’t have to 

see it yourself for long!).

You can have as many commands as you want, ranging from pre-programmed ones to ones that you can 

create. Here are some common ones:

 {NAV_WAYPOINT n/a, alt, lat, lon}

 {NAV_TAKEOFF pitch, target altitude}

 {NAV_LAND n/a, alt, lat, lon}

 {DO_JUMP waypoint, n/a, repeat count, n/a} Goes to that waypoint and resumes mission 

there. Set repeat count to any number greater than 1 to do it that many times. or to -1 to do 

it forever. Good for looping missions.

(Note: DO_xxx commands currently need a dummy waypoint placed after the command

eg:

 WAYPOINT_1

 DO_SET_HOME

 WAYPOINT_2

Home will be set at WAYPOINT_1 but will not work if WAYPOINT_2 is not there.)

Tips

 Prefetch: You can cache map data so you don’t need Internet access at the field. Click the 

Prefetch button, and hold down Alt to draw a box to download the selected imagery of a 

location.

 Grid: This allows you to draw a polygon (right click) and automatically create waypoints over 

the selected area. Note that it does not do “island detection”, which means if you have a big 

polygon and a little one inside of that, the little one will not be excluded from the big one 

(see this for more). Also, in the case of any polygon that partially doubles backs on itself (like 

the letter U), the open area in the center will be included as part of the flyover.

 Setting your home location to the current location is easy, just click “Home Location” above 

where you enter your home location, and it will set your home location to the current 

coordinates.

 You can measure the distance between waypoints by right-clicking at one end and selecting 

Measure Distance. Then right-click on the other end and select Measure Distance again. A 

dialog box will open with the distance between the two points.
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Setting a Home Position

For APM: Copter the home position is set as the location where the copter was armed. This means if you 

execute an RTL in APM: Copter, it will return to the location where it was armed, so arm your copter in 

the location you want it to return to.

For APM: Plane the home position is the location of the plane where the GPS was locked. This means if 

you execute an RTL in APM: Plane, it will return to the location where it first acquired the GPS lock, so 

only power up your plane in the location you intend it to return to when performing an RTL.

Instructions

Note: When APM: Copter executes the Land command it will land from its current location. It will not 

fly to a location, then land like the planes do. If you want to land at a particular waypoint, you must 

fly to a normal WP, then the next command will be Land. The Absolute Altitude checkbox in the 

Mission Planner is ignored. Ardu Copter only uses the default relative altitude.

In the screenshot above, a mission for Ardu copter starts with an auto takeoff to 20 meters attitude; 

then goes to WP 2 rising to 100 meters altitude on the way, then waits 10 seconds; then the craft will 

proceed to WP 3 (descending to 50 meters altitude on the way), then returns to launch. Since the 

default altitude is 100 meters, the return to launch will be at 100 meters. After reaching the launch 

position, the craft will land. The mission assumes that the launch position is set at the home position.
Page | 93

You can enter waypoints and other commands (see below for the full list). In the dropdown menus on 

each row, select the command you want. The column heading will change to show you what data that 

command requires. Lat and Lon can be entered by clicking on the map. Altitude is relative to your launch 

altitude, so if you set 100m, for example, it will fly 100m above you.

Default Alt is the default altitude when entering new waypoints. It’s also the altitude RTL (return to 

launch) mode will fly at if you have “Hold Default ALT” checked; if you don’t have that checked, your 

aircraft will try to maintain the altitude it was at when you switched on RTL.

Verify height means that the Mission Planner will use Google Earth topology data to adjust your desired 

altitude at each waypoint to reflect the height of the ground beneath. So if your waypoint is on a hill, if 

this option is selected the Mission Planner will increase your ALT setting by the height of the hill. This is 

a good way to make sure you don’t crash into mountains!

Once you are done with your mission, select “Write” and it will be sent to APM and saved in EEPROM. 

You can confirm that it’s as you wanted by selecting “Read”

You can save multiple mission files to your local hard drive by selecting “Save WP File” or read in files 

with “Load WP File” in the right-click menu:
Page | 94

Auto Grid

You can also have the Mission Planner create a mission for you, which is useful for function like mapping 

missions, where the aircraft should just go back and forth in a “lawnmower” pattern over an area to 

collect photographs.

To do this, in the right-click menu select Polygon and draw a box around the area you want to map. 

Then select Auto WP, Grid. Follow the dialog box process to select altitude and spacing. The Mission 

Planner will then generate a mission that looks something like this:

Basic Waypoint Commands

Waypoint

Option Alt Lat. Lon.

Delay (seconds) Altitude (meters) Latitude Longitude

 Mavlink command is NAV_WAYPOINT

 Delay option is triggered after the craft reaches the waypoint radius. The Next command is 

loaded after the delay.

 Delay time is in seconds, the default is 0
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Waypoint Option Bitmask – no yet available in the Mission Planner

bit 0 Altitude is stored 0: Absolute 1: Relative

bit 1 Change Alt Between WP 0: Gradually 1: ASAP

bit 2

bit 3 Req. to hit WP. Alt to continue 0: No 1: Yes

bit 4 Relative to Home 0: no 1: Yes

bit 5

bit 6

bit 7 Move to next Command 0: Yes 1: No

LOITER_UNLIM

Option Alt. Lat Lon.

N/A N/A N/A N/A

 Will cause the craft to begin to Loiter at the current location when the command is invoked.

LOITER_TIME

Option Alt. Lat. Lon.

Time (Seconds) Altitude (Meters) Latitude Longitude

 Will cause the craft to begin to Loiter at the current location when the command is invoked.

 Optionally give a location to loiter at that wp – The clock starts ticking after the WP is 

reached.

LPITER_TURNS

Option Alt. Lat. Lon.

Number of turns (N x 360°) Altitude (Meters) N/A N/A

 Will cause the craft to begin to orbit the current location when the command is invoked.

RETURN_TO_LAUNCH

Option Alt. Lat. Lon.

N/A Altitude (Meters) N/A N/A

 Will cause the craft to return to the home position set when the craft is armed (requires GPS 

Lock!)

 If Altitude is 0, craft will return to home at the altitude specified by the Mission Planner

LAND

Option Alt. Lat. Lon.

N/A N/A N/A N/A

 Will cause the craft to land at the current location when the command is invoked.

 If you have Sonar, the craft will stop holding position at 3 meters and drop straight down.

 The motors will not stop on their own, you must exit the AP mode to cut the engines
Page | 96

TAKEOFF

Option Alt. Lat. Lon.

N/A Altitude (Meters) N/A N/A

 Will cause the craft to take off and hold position until the altitude is reached.

CONDITION_DELAY

Option Dis. Lat. Lon.

N/A Distance (Meters) N/A N/A

 Will override the next waypoint altitude.

 Useful when used after a delay or distance conditional command

CONDITION_CHANGE_ALT

Option Alt. Lat. Lon.

N/A Altitude (Meters) N/A N/A

 Will override the next waypoint altitude.

 Useful when used after a delay or distance conditional command

CONDITION_YAW

Option Alt. Lat. Lon.

Direction (1=Clockwise, 

0=Counter Clockwise)

Relative: amount 

(degrees), Absolute: 

ending angle 

(degrees)

Speed (Meters) Relative angle change = 

1, Absolute = 0

 Fine grain controls of the Yaw

DO_SET_MODE

Option Alt. Lat. Lon.

N/A N/A N/A N/A

 Not Implemented

DO_JUMP

Option Alt. Lat. Lon.

The desired command 

index

N/A # of Jumps N/A

DO_CHANGE_SPEED

Option Alt. Lat. Lon.

Speed (Meters/sec.) N/A N/A N/A

* Speed change will stick until reboot
Page | 97

DO_SET_RELAY

Option Alt. Lat. Lon.

1 = on, 0 = off, -1 = toggle N/A N/A N/A

* Toggling the Relay will turn an off relay on and vice versa

DO_ REPEAT _RELAY

Option Alt. Lat. Lon.

N/A # of repetitions Cycle time (seconds) N/A

* Toggling the Relay will turn an off relay on and vice versa

DO_SET_SERVO

Option Alt. Lat. Lon.

Servo channel (5-8) PWM (1000-2000) # of repetitions Cycle time (seconds)

DO_CONTROL_VIDEO

Option Alt. Lat. Lon.

N/A N/A N/A N/A

DO_SET_ROI

Option Alt. Lat. Lon.

Yaw tracking option Altitude (Meters) Latitude Longitude

 Setting will persist until reboot

 The location is optional

 The option is a number from 0 to 4

 MAV_ROI_NONE = 0: Yaw will hold its current angle

 MAV_ROI_WPNEXT = 1: Yaw will point at next WP

 MAV_ROI_WPINDEX = 2: Yaw will point at the desired WP at the index #

 MAV_ROI_LOCATION = 3: Yaw will point at the indicated location (The location in the command)

 MAV_ROI_TARGET = 4: Not implemented

Note: When you’re using the Jump command, remember that waypoint logic can be a bit confusing. A 

waypoint command means “start heading to this WP”, not “wait until you get to this WP.” So, for 

example, if you put a “Jump to WP1′′ command in-between WP4 and WP5, the aircraft will never get 

to WP5. That’s because once it starts heading in the direction of WP5, it then executes the next 

command, which is the jump, and that takes priority. So in that instance, if you want the aircraft to hit 

WP5, you’d create a fake WP6 and issue the Jump command after that.
Page | 98

Data-flash Logs

Log Types (Data-flash vs. tlog)

There are two ways to record your flight data with Ardu Copter. With some exceptions, the two 

methods record very similar data but in different ways:

 dataflash logs (the subject of this page) use the APM or PX4′s onboard dataflash memory, which 

you can download after the flight. On Ardu Plane and Ardu Rover dataflash logs are created 

soon after start-up. On Ardu Copter they are created after you first arm the copter.

 telemetry logs (also known as “tlog”) are recorded by the mission planner (or other ground 

station) when you connect your APM to your computer via your 3DR or Xbee wireless telemetry 

link.

Setting what data you want to record

The LOG_BITMASK parameter controls what message types are recorded in the dataflash. If you only 

wish to enable one particular message type in addition to the defaults you can use the Log Bitmask drop 

down in the Mission Planner’s Advanced Parameters list.
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For better control of exactly which messages are recorded you can use the CLI (command line interface) 

as follows:

 Go to the Mission Planner’s Terminal screen

 Press “Connect APM” or “Connect PX”

 type logs

 enable or disable one of the possible messages types by typing enable or disable followed by 

the message type. I.e enable IMU

The full list of possible dataflash messages for Ardu copter is:

ATT : roll, pitch and yaw (recorded at 50hz if enabled with ATTITUDE_FAST, 10hz if enabled 

with ATTITUDE_MED)

CAMERA : GPS time, vehicle roll, pitch, yaw, lat, lon and altitude at the moment the camera shutter 

is triggered

CMD : commands received from the ground station or executed as part of a mission

COMPASS : raw compass values and compassmot compensation values

CURRENT : battery voltage, current and board voltage information recorded at 10hz

CTUN : throttle and altitude information including pilot throttle input, sonar alt, and baro alt. 

recorded at 10hz

D32: id = 9, Simple Mode’s initial heading in centi-degrees (i.e. 18000 = south)
Page | 100

DU32: id = 7, bit mask of internal state. The meaning of individual bits can be found in Ardu

Copter.pde’s definition of the ap structure.

ERR: error subsystem and error number. A list of these can be found on the “Diagnosing problems 

using LogFiles” wiki page.

EV: an event number. The full list of possible events can be found in defines.h but the most common 

are:

10 = Armed

11 = Disarmed

15 = Auto Armed (pilot has raised throttle above zero and autopilot is free to take control of 

throttle)

16 = Takeoff

18 = Land Complete

25 = Set Home (home location coordinates have been capture)

GPS : gps position, altitude, number of satellites, hdop recorded at the update rate of the GPS 

(usually 5hz)

IMU : raw accelerometer and gyro information recorded at 50hz

INAV : inertial navigation altitude and position

MOTORS : individual motor levels recorded at 50hz

NTUN : navigation data including desired and actual velocity, desired acceleration, desired roll and 

pitch angles. recorded at 10hz while the autopilot is controlling the horizontal position (Loiter, RTL, 

Auto modes)

OPTFLOW : optical flow sensor velocities and desired roll and pitch angles if OF_LOITER is engaged

PID : resulting P, I and D outputs of the PID controller if it is being tuned with the CH6 tuning knob. 

recorded at 50hz

PM : performance information including number of loops running slow, longest loop time in ms 

(recorded once every 10seconds)

 Please note that there is a significant performance impact if you enable too many logs so in 

general you should stick with the defaults and only enable expensive logging like INAV, MOTORS 

and IMU when you need them to do some specific analysis.

 If you want to see which items you can log for other platforms, do the next steps:

 Note which items are enabled before you do the next steps – write down the list.
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 Type Enable All at the cli prompt. That will enable logging of all parameters for your 

platform – some of which you may not want. You will see the new list of all items now 

being logged.

 To remove the items in the list you do not want – I.E. to return to the values initially set 

for logging type “disable” followed by the item name. Or you can go back to the 

Software – Advanced Parameters and use the Log bitmask(LOG_BITMASK) parameter 

and select one of the configurations for your vehicle.

Downloading Logs with the Mission Planner

 Go to the Mission Planner’s Terminal Screen

 Click “Connect APM” or “Connect PX4′′

 When the prompt appears click “Log Download”

 When the “Log” window appears click the checkbox of the log you wish to download (normally 

the highest number)

 Select your vehicle type (APM: Copter, APM_Plane, and APM: Rover). This ensures you get the 

correct scaling for a few parameters as the data is downloaded.

 Push “Download These Log”

For very large logs it can take several minutes to download but you should see the amount of data 

transferred so far in light grey just below the “Clear Logs” button. When the file is completely 

downloaded “Done” should appear in the area below the Clear Logs button..
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The Log will appear in your Mission Planner’s directory (the directory where the mission planner was 

installed) in a folder called “logs” or in the location you select in the Planner options [Config/Tuning] 

[Planner]. The file will be of the format: YYYY-MM-DD HH-MM ##.log where the date portion is the 

current date and the ## is the log number.

Along with the log file will be a .kmz file which show you a 3D view of the flight path if opened in Google 

Earth. A .gpx file is also produced but is rarely used.

Clearing logs:

 The Clear Logs button on the same screen will clear all logs when pushed.

 It is a good idea to save those log files you want to keep and clear all logs before a day of flying.

 Once the data-flash memory card is full it will wrap around and start overwriting the oldest logs.

Viewing the contents

Dataflash files can be opened for analysis by doing the following:

 Open the Mission Planner’s Terminal Screen

 push Log Browse button and open the .log dataflash file

The Log Browser screen will appear with a graphing area at the top. This graphing area’s size can be 

changed by clicking and holding on the area just below the graph but above the green graphing buttons.

The basic format of the dataflash is:

 Line numbers appear on the very left side of the viewer

 Software version and board type appear at the top

 FMT messages are next which tell the mission planner the column headers for each message 

type

 PARM rows which show each parameter (in the order in which they appear in the eeprom) along 

with their value at the beginning of the flight

 Flight data messages including GPS, IMU, etc.
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Graph any flight data by first clicking on the appropriate row, you should see the column headers update 

appropriately. Next find the column you wish to graph, click on it and then push the “Graph this data” 

button. In the example above the ATT’s Roll-In and Roll data have been graphed.

The mouse’s scroll wheel can be used to zoom in or out. You may also select an area of the graph to 

zoom in on it. Zoom out by right-mouse-button clicking and selecting “Set Scale to Default”.

You may also filter on just the first column (the flight data message type) by clicking on the first column 

and selecting the message type from the drop-down. This is very useful especially for viewing the 

different flight modes (called “MODE” messages) used during the mission. Click the first column again 

but press “Cancel” to clear the filter.
Page | 104

Message Details (APM: Copter specific)

ATT (attitude information):

RollIn: the pilot’s desired roll angle in centi-degrees

Roll: the vehicle’s actual roll in centi-degrees

PitchIn: the pilot’s desired pitch angle in centi-degrees

Pitch: the vehicle’s actual pitch angle in centi-degrees

YawIn: the pilot’s desired yaw rate as a number from -4500 ~ 4500 (not necessarily in deg/sec or 

any other understandable unit)

Yaw: the vehicles actual heading in centi-degrees with 0 = north

NavYaw: the desired heading in centi-degrees

CAM (time and position when camera shutter was activated):

GPSTime : the GPS reported time since epoch in milliseconds

Lat : the accelerometer + GPS latitude estimate

Lat : the accelerometer + GPS longitude estimate

Alt: the accelerometer + barometer estimated altitude in cm above ground

Roll: the vehicle roll angle in centi-degrees

Pitch: the vehicle pitch angle in centi-degrees

Yaw: the vehicle’s heading in centi-degrees

CMD (commands received from the ground station or executed as part of a mission):

CTot: the total number of commands in the mission

CNum: this command’s number in the mission (0 is always home, 1 is the first command, etc)

CId: the mavlink message id

Copt: the option parameter (used for many different purposes)

Prm1: the command’s parameter (used for many different purposes)

Alt: the command’s altitude in meters

Lat: the command’s latitude position
Page | 105

Lng: the command’s longitude position

COMPASS (raw compass, offset and compassmot compensation values):

MagX, MagY. MagZ: raw magnetic field values for x, y and z axis

OfsX, OfsY, OfsZ: raw magnetic offsets (will only change if COMPASS_LEARN parameter is 1)

MOfsX, MOfsY, MOfsZ: compassmot compensation for throttle or current

CURRENT (battery voltage, current and board voltage information):

Thr: pilot input throttle from 0 ~ 1000

ThrInt: integrated throttle (i.e. sum of total throttle output for this flight)

Volt: battery voltage in volts * 100

Curr: current drawn from the battery in amps * 100

Vcc: board voltage

CurrTot: total current drawn from battery

CTUN (throttle and altitude information):

ThrIn: the pilot’s throttle in as a number from 0 to 1000

SonAlt: the altitude above ground according to the sonar

BarAlt: the altitude above ground according to the barometer

WPAlt: the desired altitude while in AltHold, Loiter, RTL or Auto flight modes

NavThr: not used

AngBst: throttle increase (from 0 ~ 1000) as a result of the copter leaning over (automatically 

added to all pilot and autopilot throttle to reduce altitude loss while leaning)

CRate: accelerometer + baro climb rate estimate in cm/s

ThrOut: final throttle output sent to the motors (from 0 ~ 1000). Normally equal to ThrIn while 

in stabilize mode.

DCRate – pilot desired climb rate in cm/s

D32, DU32 (single data values which are either signed 32bit integers or unsigned 32bit integers):

id: identification number for the variable. There are only two possible values
Page | 106

7 = bit mask of internal state. The meaning of individual bits can be found in ArduCopter.pde’s 

definition of the ap structure.

9 = simple mode’s initial heading in centi-degrees

ERR (an error message):

SubSystem and Error codes listed below

1. 1: Main (never used)

2. 2: Radio

ECode 1: “Late Frame” which means the APM’s onboard ppm encoder did not provide 

an update for at least 2 seconds

ECode 0: error resolved which means the ppm encoder started providing data again

3. Compass

ECode 1: the compass failed to initialize (likely a hardware issue)

ECode 2: failure while trying to read a single value from the compass (probably a 

hardware issue)

ECode 0: above errors resolved

4. Optical flow

Ecode 1: failed to initialize (likely a hardware issue)

5. Throttle failsafe

ECode 1: throttle dropped below FS_THR_VALUE meaning likely loss of contact between 

RX/TX

ECode 0: above error resolve meaning RX/TX contact likely restored

6. 6: Battery failsafe

ECode 1: battery voltage dropped below LOW_VOLT or total battery capacity used 

exceeded BATT_CAPACITY

7. GPS failsafe

ECode 1: GPS lock lost for at least 5 seconds

ECode 0: GPS lock restored
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8. GCS (Ground station) failsafe

ECode 1: updates from ground station joystick lost for at least 5 seconds

ECode 0: updates from ground station restored

9. Fence

ECode 1: altitude fence breached

ECode 2: circular fence breached

ECode 3: both altitude and circular fences breached

ECode 0: vehicle is back within the fences

10. Flight Mode

ECode 0 ~ 10: the vehicle was unable to enter the desired flight mode

(0=Stabilize, 1=Acro, 2=AltHold, 3=Auto, 4=Guided, 5=Loiter, 6=RTL, 7=Circle, 8=Position, 

9=Land, 10=OF_Loiter)

GPS:

Status – 0 = no GPS, 1 = GPS but no fix, 2 = GPS with 2D fix, 3 = GPS with 3D fix

Time: the GPS reported time since epoch in milliseconds

NSats: the number of satellites current being used

HDop: a measure of gps precision (1.5 is good, >2.0 is not so good)

Lat: Latitude according to the GPS

Lng: Longitude according to the GPS

RelAlt: Accelerometer + Baro altitude in meters

Alt: GPS reported altitude (not used by the flight controller)

SPD: horizontal ground speed in m/s

GCrs: ground course in degrees (0 = north)

IMU (accelerometer and gyro information):

GyrX, GyrY, GyrZ: the raw gyro rotation rates in degrees/second

AccX, AccY, AccZ: the raw accelerometer values in m/s/s
Page | 108

INAV (inertial navigation position and velocity estimates):

BAlt: barometer altitude in cm

IAlt: inertial nav altitude estimate in cm

IClb: inertial nav estimated climb rate in cm/s

ACorrX. ACorrY, ACorrZ: x, y and z-axis accelerometer correction in cm/s/s

GLat, GLon: GPS latitude and longitude from home

ILat, ILng: inertial nav latitude and longitude from home

Mode (flight mode):

Mode: the flight mode displayed as a string (i.e. STABILIZE, LOITER, etc)

ThrCrs: throttle cruise (from 0 ~ 1000) which is the autopilot’s best guess as to what throttle is

required to maintain a stable hover

Motors (pwm output to individual motors):

Mot1, Mot2, etc : pwm command sent from flight controller to the esc/motor

NTUN (navigation information):

WPDst: distance to the next waypoint (or loiter target) in cm. Only updated while in Loiter, RTL, 

Auto flight modes.

WPBrg:bearing to the next waypoint in degrees

PErX: distance to intermediate target between copter and the next waypoint in the latitude 

direction

PErY:distance to intermediate target between copter and the next waypoint in the longitude 

direction

DVelX: desired velocity in cm/s in the latitude direction

DVelY: desired velocity in cm/s in the longitude direction

VelX: actual accelerometer + gps velocity estimate in the latitude direction

VelY: actual accelerometer + gps velocity estimate in the longitude direction

DAcX: desired acceleration in cm/s/s in the latitude direction

DAcY: desired acceleration in cm/s/s in the longitude direction
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DRol: desired roll angle in centi-degrees

DPit: desired pitch angle in centi-degrees

PM (performance monitoring):

RenCnt: DCM renormalization count – a high number may indicate problems in DCM (extremely 

rare)

RenBlw:DCM renormalization blow-up count – how many times DCM had to completely rebuild 

the DCM matrix since the last PM. Normally innocuous but a number that constantly grows may 

be an indication that DCM is having troubles calculating the attitude (extremely rare)

FixCnt: the number of GPS fixes received since the last PM message was received (it’s hard to 

imagine how this would be useful)

NLon: number of long running main loops (i.e. loops that take more than 5% longer than the 

10ms they should)

NLoop: the total number of loops since the last PM message was displayed. Normally 1000 and 

allows you to calculate the percentage of slow running loops which should never be higher than 

15%.

MaxT: the maximum time that any loop took since the last PM message. This should be close to 

10,000 but will be up to 6,000,000 during the interval where the motors are armed

PMT: a number that increments each time a heart beat is received from the ground station

I2CErr: the number of I2C errors since the last PM message. Any I2C errors may indicate a 

problem on the I2C bus which may in turn slow down the main loop and cause performance 

problems.

Viewing KMZ FILES

When you download the dataflash log files from the APM/PX4 it will automatically create a KMZ file (file 

with extension .kmz). This file can be opened with Google Earth (just double click the file) to view your 

flight in Google Earth. Please see the instructions on the Telemetry Logs Page for additional details.
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Mission Planner Telemetry Logs

Tlogs are recordings of the MAVLink telemetry messages sent between the APM/PX and the ground 

station and are automatically created the moment you press the connect button on the mission 

planner. Files of the format YYYY-MM-DD hh-mm-ss.tlog appear in the “logs” subfolder in your Mission 

Planner installation folder or to the location you select in the Planner options [Config/Tuning] [Planner].

Besides the “.tlog” files, “.rlog” files are also created. These contain all the .tlog data plus additional 

debug output from the mission planner. but cannot be parsed or played back so they should be ignored.

Setting the data rate

The desired rate at which data is sent from the APM/PX to the ground station can be controlled through 

the mission planner’s Software > Planner screen’s Telemetry drop-downs. Because all data sent over 

the telemetry link is also recorded in the tlog, this also controls the rate of data saved to the tlogs.

Note that especially on Ardu Copter, due to CPU resource limitations, the actual rate of the data sent 

and saved may be lower than the rate requested.

Playing back missions

If you are using wireless telemetry and have connected to APM via the Mission Planner, your flight data 

will automatically recorded. You can play back these logs by doing the following:

 Open the mission planner’s Flight Data screen

 click on the Telemetry Logs tab

 Press “Load Log” and find the flight’s tlog file

 Press “Play”
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You can also jump to the point of interest in the log using the slider and control the speed of the 

playback with the predefined Speed buttons.

While the log is replaying, the HUD will move and the vehicles location on the map will update as it did 

during the flight. Individual data values can be seen through the Status tab and you can even display 

them in a graph by clicking on the “Tuning” checkbox under the map and then double clicking on the 

data legend to bring up a box from which you can choose exactly which data fields are graphed as 

shown below. This will show the recorded data changing as the flight progresses.
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Creating 3d images of the flight path

You can create KMZ files by doing this:

 Open the mission planner’s Flight Data screen

 Click on the Telemetry Logs tab

 Press the “Tlog > Kml or Graph” button

 Press the “Create KML + GPX” button

 select the flight tlog

A .kmz and .kml file will be created 

alongside the original .tlog and this can 

be opened in Google earth to 

interactively view the 3d flight path. You 

can open the kmz file in Google Earth to 

view the flight or path. Just double click 

the file or drag it and drop into Google 

Earth.

The different flight modes used during the flight will appear as different colored tracks. You can change 

some details about how the flight paths are displayed including their color and whether the paths 

extend to the ground by doing this:

 Find the log file’s name in the “Places” 

pane on the left. It should appear in a 

“Temporary Places” folder.

 Right click on an individual path and select 

“Properties” to open the Edit Path 

window.

 The color can be changed on the “Style, 

Color” tab

 The area below the path can be removed 

(added) on the “Altitude” tab by unchecking (checking) “Extend path to 

ground”

Extracting parameters and Waypoints

You can extract the parameters and waypoints from the tlog by following the same steps as for creating 

the KML file except that at the last step select “Extract Params” or “Extract WPs”.
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Extract Params will cause a .param file to be created alongside the tlog. This file is tab separated and 

contains a full list of parameters (in the same order as they appear in the eeprom) along with their 

values during the flight. This can be opened in excel or a text editor.

Extract WPs will create one or more .txt files containing any missions uploaded to the APM/PX4. These 

files can be opened in the Mission Planner by switching to the Flight Plan screen, right-mouse-button 

clicking on the map and selecting “File Load/Save”, “Load WP File”.

Graphing data from a flight

Data from the flight can be graphed by doing 

the following:

 Open the mission planner’s Flight 

Data screen

 Click on the Telemetry Logs tab

 Press the “Tlog > Kml or Graph” 

button

 Press the “Graph Log” button

 select the flight tlog

 When the “Graph This” screen 

appears, use the left or right mouse button to click on the checkboxes beside the items you wish 

to graph. Note that the items are grouped into categories like “RC_CHANNELS” and 

“RAW_IMU” although it’s still often difficult to find exactly the item you wish to graph

 If you use the left mouse button the scale for the item will appear on the left of the graph. If 

you use the right mouse button it will appear on the right

 Click the checkbox multiple times to cycle through all the possible colors

 Change the zoom of the graph with your mouse’s middle wheel, by select an area of the graph 

with the left mouse button held down or by right-mouse-button clicking on the graph and 

selecting “Set Scale To Default”
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Using a Ground Station

1. Air speed ( Ground speed if no airspeed sensor is fitted )

2. Crosstrack error and turn rate (T)

3. Heading direction

4. Bank angle

5. Wireless telemetry connection (% 

bad packets)

6. GPS time

7. Altitude ( blue bar is rate of climb )

8. Air speed

9. Ground speed

10. Battery status

11. Artificial Horizon

The above is the main Ground Station view of the Mission Planner, showing the Heads-up Display (HUD). 

If your APM slider switch is in flight mode (away from the RC pins) and you have connected via MAVLink 

(usually through the Xbee modules at 57600k, but it will work via USB on the ground, too) the dials and 

position on this screen will display the telemetry sent by APM.

A few tips:

 The map will only show current position when you have GPS lock or are using a flight simulator
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 Remember how artificial horizons work: when the aircraft tilts to the right, the horizon tilts to 

the left. (Just tilt your head and you’ll see what I mean). This is normal! Please don’t tell us it’s 

reversed ;-)

 For APM: Copter status, the output meaning is as follows:

 “WPDist” : Distance to next waypoint in meters

 “Bearing ERR”: How far your UAV is from the perfect line to the next waypoint

 “Alt ERR”: How far your UAV is from the target altitude

 “WP”: Next waypoint to hit

 “Mode”: Current autopilot mode.

 You can issues mode changes and other action commands in the air with the Mission Planner 

and other GCSs, but note that you must be under autopilot control for them to take effect.

 If you double-click the HUD it will pop out, allowing you to run the HUD full screen on a second 

screen.

 If you double-click on the Speed Gauge you can modify the max scale you want to display.

 You can change the voice used in the speech synthesis in the Ease of Access center in Windows 

Control Panel. Go to the “Text to Speech” options.

 If you enable the Tuning checkbox and double-click tuning you can graph any data that is 

available in the status tab. This means you can have alt, attitude, or many other options in real 

time.

 You can use custom imagery instead of Google Maps. Press control-F. This allows you to upload 

your own ortho-photos. Use will require Global mapper, as this is currently one of the key steps 

in exporting in the required format for use in the planner.

Guided Mode

One of the most commonly-used features in pro 

UAVs is point-and-click mission control in real 

time. Rather than just pre-planned missions or 

manually flying the UAV, operators can just click 

on a map and say “go here now”.

That’s now implemented in the Mission Planner. 

On the GCS map, you can right-click on the map 

and just select “Fly To Here”. The UAV will fly 

there and loiter until you give it another 

command. We call this “Guided Mode”. There 

are more commands coming in this mode soon, but the functionality is now built-in.

Note: Guided is a separate flight mode. If you enter it you will remain in it until you do something to 

change modes. So if you tell it to “go here now”, once it arrives there it will loiter at the Guided 

waypoint till you tell it to do something else. Something else could either be going to another Guided 

waypoint (staying in Guided mode) or changing to some other flight mode. If you change to Auto your 

mission will resume where it left off.
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APM 2.6

 APM 2.6 is a revision of the APM that makes use of an external magnetometer (compass).

 The APM 2.6 has no on board compass, and is optimized for vehicles where the compass should 

be placed as far from power and motor sources as possible to avoid magnetic interference.

 APM 2.6 is designed to be used with the 3DR GPS uBlox LEA-6 with Compass module.

 The GPS/Compass module may be mounted further from noise sources than the APM itself.

 APM 2.6 requires a GPS unit with an on board compass for full autonomy.

 For information on installing a 3DR GPS uBlox LEA-6 with Compass, visit (Here!).

 Details APM 2.0
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Using the APM 2.5/2.6 Enclosure

The APM 2.5/2.6 board is shipped in an enclosure with foam protecting the barometric pressure sensor, 

as shown here.

Powering the APM 2.5/2.6 Board

Like any computer, the APM needs a power supply with a steady clean voltage and sufficient current.

3DR provides an APM power module that supplies 2.25A at 5.37V. The module is designed to convert 

power from the main flight battery (18 volt maximum). That module will supply sufficient power for 

your APM, and low power 

radios including your RC 

receiver (without servos). 

Your RC receiver can be 

powered from any APM Input 

(+5V and ground). This is 

normally done by connecting 

a 2 or 3 wire cable between 

an APM Input and one of the 

output channels on the RC 

radio.

If you are using any servos 

such as are required with a 

traditional helicopter or a 

camera gimbal, you will need 
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to provide an additional dedicated power supply for the servos. The APM is intended to control servos, 

not power them.

In order to design a power supply for your APM, or provide additional power, you’ll need a basic 

understanding of the power circuit in the APM.

There are two “sides” to the positive circuit in the board. Each side has positive-rails available for 

inputting power or distributing it to peripheral devices. The center row of pins in the three groups of 

pins (Outputs, Inputs, Analog) labeled “+” are referred to as a “positive-rail”. This means that the base of 

all the + pins are connected so they represent a single electrical path. The positive-rails of the Input and 

Analog group are connected together. So we have two separate positive circuits, one in the Outputs and 

the other made up of the Input/Analog.

All of the components on the board take power from various points on these rails, so it is necessary for 

both “sides” to be receiving +5V (within the specs below) for the board to function.

These positive-rails can be joined together by placing JP1 in its position on the board. This connects all 

the positive-rails and provides power to both sides of the board, so that low-level power can be 

distributed to peripheral sensors and devices: 3DR Radios, sonar, RC Rx, etc. via the power-rails.

When using the power module, the circuit path is as follows:

From the power module connection the negative wire is connected to a negative-rail shared by the 

entire board regardless of JP1.

Positive voltage comes in to a T-junction. to the left is a path through the JP1 to the positive-rail of the 

Outputs. To the right it flows through an over-voltage, over-current, reverse-polarity protection(500mA 

fuse and 6V Zener diode). A side effect of passing through the Zener diode is a .37V loss, therefore input 

voltage should be bumped up by .37V to account for this. From here the positive voltage runs to the 

positive-rails of the Inputs and Analog. Inputs should not be used to power anything except your RC 

receiver.

Higher current loads such as servos should be powered from the power-rails (positive-negative) of the 

Output side. You must use an adequate voltage-regulator to provide power directly to the Output 

power-rails, all servo power leads will attach to these same rails (the signal wires can connect on the 

Analog “S” pins in the case of a camera gimbal). Since JP1 is removed in this scenario, the other “side” of 

the board will need power provided to its power-rails directly.
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Alternative ways to power your board

3DR Power Module

If you are using the 3DR Power:

 Warning! Under no circumstances should you ever attempt to draw servo power from the 

analog input connector.

 Warning: You may “control” servos from A9, A10 and A11 from the A0 – A11 I/O connector, but 

you must run servo power separately.

 The A0 – A11 I/O connector cannot supply sufficient power for servos.

 A9, A10 and A11 of the I/O connector come pre-wired to correct digital out for use as 

servo control lines.

 For servo use, it is imperative that they have not been reassigned to analog use with the 

pads on the back of the APM board.

A Non technical Description of the Power Supply Requirements

The description below simply supplements and provides an alternate view of the information above.

1. The APM 2.5/2.6 board has two separate power circuits which make it very easy to power by a 

variety of methods.

A. A fused power circuit provides primary board and general I/O power: (It cannot provide 

power for servos).

B. The Other power circuit is for the OUTPUT connector power rail: (it can provide power 

for servos).

2. The jumper JP 1 determines whether the two power circuits are connected or separate.

A. If JP1 is removed, the power rail on the OUTPUT connector “Floats” and may be used to 

distribute power.

B. Although if JP1 is removed the OUTPUT connector cannot be used to supply power to 

the APM board.

3. It is possible to power the APM board from the Power Module connector or the OUTPUT or 

INPUT connectors.

4. Normally the APM 2.5/2.6 “Power Module” is used to provide primary APM 2.5 board and 

general I/O power.

5. Alternatively primary board power can be supplied by a BEC either from one of the ESCs or from 

an external BEC.

6. If servos are used, supplementary power is required.

A. Generally one power supply is provided for the board and one or more additional power 

supplies for the servos.

B. But if a sufficiently large external BEC is used it can supply power for both via the 

OUTPUT connector.

7. Only the OUTPUT connector can provide power for servos as the other circuit is fused.

A. The address connector is sometimes used provide servo signals, but the servos power 

must come from elsewhere.
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8. How you are powering your APM board and or servos determines whether JP1 is installed or 

not.

A. (Whether the two power circuits are separated or connected).

B. All possible configurations are detailed Below.

9. The type of use will determine which options are available.

A. APM: Copter can power the APM from a power module or a UBEC or a BEC from one of 

the ESCs and can power servos from a UBEC or from the other ESC’s BECs.

B. APM: Plane can power the APM from the power module, the BEC from the flight 

motors ESC or a separate UBEC and can power servos from a separate UBEC or the 

flight motors BEC if it is large enough.

C. APM: Rover can power the APM from the power module, the BEC from the drive 

motor’s ESC or a separate UBEC and can power the steering servo from a separate 

UBEC or the drive motors BEC if it is large enough.

Power Supply Rails Connected Requirements (JP1 Installed)

Warning: Do not exceed Abs MAX input voltages when connecting the power supply or you will damage 

your board.

Warning: Connecting USB when you have input voltages at the high end of the range (near Abs Max) can 

damage the board. Disconnect battery before connecting USB or test input voltages so they are within 

the specified range.

Power Options Nominal Abs MAX JP1 Status

Power on Output PWM connector 5.37V +/- 0.5 6V JP1 Connected

Power on Input PWM connector 5.00V +/- 0.25 5.5V JP1 Connected

No Power Module and No Servos and Power provided by BEC from ESC

 If you do not have a power module and you are not using servos.

 Ensure JP1 is installed and provide the necessary power via the BEC from one of your ESC’s.

 Connect one ESC’s BEC power and ground wires to one pair of the APM OUTPUT connector’s

power and ground pins.

 Clip the BEC power leads on the remaining 3 wire connectors.

 Ensure that the ESC’s signal wires are connected to the appropriate APM OUTPUT connector 

signal pins.

 You must ensure that your ESC’s BEC has a sufficient power capability (at least 2 amps).

 Most 20 amp or higher ESCs have 2 amp BECs.

No Power Module but using Servos and a high power External BEC

 If you do not have a power module and are using servos you can use a high power external BEC.

 Ensure JP1 is installed and provide the necessary power via a high power external BEC (5 to 10 

amps or more).

 The BEC power must be provided to one pair of the APM OUTPUT connector pins.

 Warning! Clip all power leads on the ESC’s BECs (they would conflict with the external BEC).

 Your servos will determine the size of the BEC required.
Page | 121

 You should allow at least 2 or 3 amps extra to power the APM, receiver and to prevent (brown 

outs).

 All of the positive power for driving each servo must come from the OUTPUT connector.

 This is true even if the servo(s) signal wires are connected to the ADDRESS connector.

 This option requires you to take responsibility for providing sufficient power to prevent 

brownout.

No Power Module but using Servos and multiple BECs from ESC’s (A BEC for 

each Servo)

 If you do not have a power module and are using servos you can use multiple BECs from your 

ESC’s.

 Ensure JP1 is installed and plug one of your ESC’s signal cables with power leads into the 

OUTPUT connector.

 Remove the power and ground leads from the remaining ESCs signal cable connectors.

 Plug the signal wire connector from each ESC onto the appropriate pin on the 

OUTPUT connector.

 You can heat shrink these or plug them into a multi-wire connector appropriate for your 

copter.

 Connect one pair of each of the remaining BEC power and ground lines to the power and ground 

of each individual servo.

 Clip or heat shrink any remaining excess BEC power and ground leads.

 The BEC power from one ESC must be provided to one pair of the APM output connector pins.

 Plug only the signal input wire from your servos into the appropriate OUTPUT or ADDRESS 

connector pin.

 Your ESC’s BECs should be at least 2 amps.

 The ESC’s BEC grounds are in common with battery and internal signal ground so grounding the 

servos this way is OK.

Power Supply Rails Not Connected Requirements (JP1 Not Installed)

Warning: Do not exceed Abs MAX input voltages when connecting the power supply or you will damage 

your board.

Warning: Connecting USB when you have input voltages at the high end of the range (near Abs Max) can 

damage the board. Disconnect battery before connecting USB or test input voltages so they are within 

the specified range.

Power Options Nominal Abs MAX JP1 Status

Power on Output PWM connector 5.00V +/- 0.5 6V JP1 open

Power on Input PWM connector 5.00V +/- 0.25 5.5V JP1 open

Power Module and No Servos

 If you have a power module and you are not using servos.

 Ensure JP1 is not installed.
Page | 122

 Provide the necessary power via the power module connected to the APM’s power module 

connector.

 When connecting your ESCs to the OUTPUT connector clip the BEC power leads on each ESC’s 3 

wire connector.

 Or connect only the ESC’s signal wires to the OUTPUT connector.

Power Module and using Servos with External BEC power

 If you have a power module and an external BEC and you are using servos.

 Ensure JP1 is Not installed

 Provide APM board and receiver power via the power module connected to the power module 

connector.

 Connect an external BEC with sufficient power for your servos to one pair of the 

OUTPUT connector power pins.

 When connecting your ESCs to the OUTPUT connector clip the BEC power leads on each ESC’s 3 

wire connector.

 Or connect only the ESC signal wires to the OUTPUT connector.

Power Module and using Servos with BEC power from one ESC

 If you have a power module and you are using servos Remove JP1.

 Provide APM and receiver power via the power module connected to the APM’s power module 

connector.

 The BEC of a single ESC must provide sufficient power for all your servos.

 When connecting your ESCs to the OUTPUT connector clip the BEC power leads on all but one of 

the ESC’s connectors.

 Or connect only the ESC signal wires to the OUTPUT connector for all except one ESC.

 And on that ESC connect all 3 wires to the OUTPUT connector.

Power Module and using Servos with BEC power from one ESC

 If you have a power module and you are using servos Remove JP1.

 Provide APM and receiver power via the power module connected to the APM’s power module 

connector.

 The BEC of a single ESC must provide sufficient power for all your servos.

 When connecting your ESCs to the OUTPUT connector clip the BEC power leads on all but one of 

the ESC’s connectors.

 Or connect only the ESC signal wires to the OUTPUT connector for all except one ESC.

 And on that ESC connect all 3 wires to the OUTPUT connector.

No Power Module and using Servos with BEC power from two ESCs

 If you do not have a power module and you are using servos remove JP1.

 Provide APM and receiver power via 1 pair of ESC-BEC power wires connected to the APM 

INPUT connector power pins.

 Also connect another of the ESCs power wire pair to the OUTPUT connector.
Page | 123

 The BEC of a single ESC must provide sufficient power for all your servos.

 Clip the signal power leads on your remaining ESC’s.

 Connect all ESC signal wires to the appropriate OUTPUT connector pins.
Page | 124

APM 2.5/2.6 Connections

1. Outputs and Inputs

2. Common negative-rail (pins closest 

to edge “-”) provides a negative 

path to complete power and signal 

circuits

3. Separate positive-rails (central pins 

“+”) for low-level power 

distribution

4. Individual sensor/signal pins (inner 

pins “S”) output control signals to 

motor-ESCs and take-in RC input 

signals from the Rx

5. Micro USB

6. Direct connection to a computer

7. Power Module

8. Provides power input and battery monitoring capability

9. 3DR Radio

10. Two-way wireless telemetry and control

11. 5.GPS

12. Input from GPS receiver (Rx)

13. Analog I/O

14. Common negative-rail (outer “-”) shared with Inputs and Outputs

15. Positive-rail (center “+”) is connected with the positive rail on the Inputs

16. Individual signal pins (inner “S”) connect with servos and sensors

17. I2C connection. 

18. Inter-Integrated Circuit, a type of serial bus. This allows multiple peripheral devices to be 

connected with a single port

19. Jumper-JP1

20. Connects the positive-rail of the Outputs to the positive-rails of the Inputs-Analog (details)

21. Optional I/O ports
Page | 125

Connecting your R/C Inputs and Motors

Connecting the RC inputs

Connect your RC receiver “S” (signal) pins to the “S” pins on Inputs 

of APM, using the jumper cable that came with your APM: Copter 

kit. You must connect at least channels 1 ~ 5. Channels 6 ~ 8 are 

optional. Your RC receiver will require power. Normally this is done 

by using one 2 or 3 wire connector between the APM Inputs and 

one channel output on the receiver

If you are using a PPM Receiver, put a jumper on the “S” inputs of channel 2 and 3, and connect the 

PPM input to channel 1.
Page | 126

Connecting the RC Outputs to the Motors

Connect the four-wire/six-wire cable from your 

power distribution board (PDB) to the 

corresponding “S” pins on the APM Outputs. It is 

not necessary to connect +5v or ground pins –

those connections are made on the PDB.
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Page | 128

Recognizing the clockwise and counter-clockwise propellers
Page | 129

Checking the motor direction the simple way

If you have completed the Radio and ESC calibration, you can check that your motors are spinning in the 

correction direction:

 Holding down your copter with the props clear of your body for safety, arm the ESCs (For a 

PX4 system, press and release the Arming button) hold your throttle stick all the way to the 

right for four seconds.

 Now gently raise the throttle just a bit, until the props start turning. Note the direction each 

one turns. They should match directions shown in the images above for the frame you’ve 

chosen.

Checking the motor direction with the CLI

An alternative way to check that the motors have been hooked up correctly is to use the “Motors” 

command in the CLI.

 Connect the APM or PX4 to your computer using the mini USB cable

 Connect the LiPo battery

 Open the Mission Planner’s Terminal window and press “Connect to APM” or “Connect to 

PX4′′ button

 On a PX4 press the safety switch

 When the prompt appears type Test

 Type motors

The motors will now spin in sequence, each motor will spin for about 1 second at very low throttle and 

then stop. The next motor will start after a 2 or 3 second delay. Please observe the direction of rotation 

for each motor and also that the motors spin one after another.

The first motor to spin will be the one located directly forward in the case of + configuration, or the first 

motor to the right of straight forward in the case of X configuration. The motor test will then proceed in 

a clockwise rotation.

In the case of X8, it will spin the top front-right motor first, then the bottom front-right, and proceed 

around with the same pattern.

Octo V will spin the front-right motor first, and then again, proceed clock-wise until reaching the front 

left motor.

After the test pattern is complete, there will be a 4 or 5 second pause before beginning again.

When you are satisfied that the motor pattern is correct:

 press any key (the process will not stop until it finishes the current sequence)

 disconnect the main motor battery

 disconnect the usb cable
Page | 130
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Glossary

NOTE: The glossary is not yet indexed. It is in alphabetical order so just scroll down to find the topic of 

interest.

2.4 GHz: The frequency used by digital (spread spectrum) radio communications in our applications, 

including 2.4Ghz RC, Bluetooth and some video transmission equipment. This is a different band than 

the older 72 MHz band that is used for analog RC communications. To avoid radio frequency conflict is it 

often a good idea to use 72 MHz radio equipment when you are using 2.4 GHz onboard video 

transmitters, or use 900 MHz video when using 2.4 GHz RC equipment.

AGL: Altitude above ground level

AHRS: Altitude Heading Reference System. An IMU (see below) plus the code to interpret the output 

from its sensors to establish a plane’s XYZ and heading orientation.

APM: ArduPilotMega.

AMA: Academy of Model Aeronautics. The main US model aircraft association. The AMA works closely 

with the Federal Aviation Administration (FAA) to establish reasonable rules for the use of amateur 

UAVs. Each AMA chapter and field may have slightly different policies, but it’s possible to fly and test air 

frames and some technology on AMA fields without violating the association’s (or FAA/NAS) rules.

Arduino: An open source embedded processor project. Includes a hardware standard currently based on 

the Atmel Atmega168 microprocessor and necessary supporting hardware, and a software programming 

environment based on the C-like Processing language. Official site is here.

APM (Autopilot Mega): Flight Controller providing capabilities for stabilized flight, position maintenance 

and automated mission (waypoint) path following.

APM: Copter: Rotary-wing autopilot software for the APM electronics

APM: Plane: Fixed-wing autopilot software for the APM electronics.

APM: Rover: Ground and water autopilot software for the APM electronics

BEC: Battery Elimination Circuit. A voltage regulator found in ESCs (see below) and as a stand-alone 

product. Designed to provide constant 5v voltage for RC equipment, autopilots and other onboard 

electronics.

Bootloader: Special software code stored in non-volatile memory in a microprocessor that can interface 

with a PC to download a user’s program. Also see Firmware.

COA: Certificate of Authorization. A FAA approval for a UAV flight. See the faa.gov web site for more 

details and the DIY Drones Regulatory FAQ.
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DCM: Direction Cosine Matrix. A algorithm that is a less processing intensive equivalent of the Kalman 

Filter. See this for more.

Eagle file: The schematic and PCB design files (and related files that tell PCB fabs how to create the 

boards) generated by the free Cadsoft Eagle program. This is the most common standard used in the 

open source hardware world, although, ironically, it’s not open source software itself. Needless to say, 

this is not optimal, and the Eagle software is clumsy and hard to learn. One hopes that an open source 

alternative will someday emerge.

ESC: Electronic Speed Control. Device to control the motor in an electric aircraft. Serves as the 

connection between the main battery and the RC receiver. Usually includes a BEC, or Battery Elimination 

Circuit, which provides power for the RC system and other onboard electronics, such as an autopilot.

Firmware: The software or sketch that is loaded into the non-volatile memory of microprocessor based 

products. It is called ‘firmware’ because it stays in the non-volatile memory even if power is removed –

thus ‘non’ – volatile. In the case of the autopilots, it is the ‘program’ or application (App to smart phone 

users) that determines what the auto pilot does, and how.

FPV: First-person view. A technique that uses an onboard video camera and wireless connection to the 

ground allow a pilot on the ground with video goggles to fly with a cockpit view.

FTDI: A standard to convert USB to serial communications. Available as a chip for boards that have a USB 

connector, or in a cable to connected to breakout pins. FTDI stands for Future Technology Devices 

International, which is the name of the company that makes the chips.

GCS: Ground Control Station. Software running on a computer on the ground that receives telemetry 

information from an airborne UAV and displays its progress and status, often including video and other 

sensor data. Can also be used to transmit in-flight commands to the UAV.

Hard Iron magnetic distortion: distortions that arise from magnets or magnetized metals on the 

airframe that affect the compass. These distortions remain in the same location relative to the compass 

for all heading orientations. These distortions can be mostly compensated for by adding constant offsets 

to the values returned from the 3d magnetometer.

HIL (Hardware-in-the-loop simulation): Doing a simulation where software running on another 

computer generates data that simulates the data that would be coming from an autopilot’s sensors. The 

autopilot is running and doesn’t “know” that the data is simulated, so it responds just as it would to real 

sensor data. Hardware-in-the-loop uses the physical autopilot hardware connected to a simulator, as 

opposed to simulating the autopilot in software, too. In an “open loop” simulation, the software 

simulator feeds data to the hardware autopilot; in a “closed loop” simulation, the hardware feeds data 

back to the software simulator, too.

I2C: A serial bus that allows multiple low speed peripherals, such as sensors, to be connected to a 

microprocessor. See this for more.
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IDE: An integrated development environment, such as the Arduino editor/downloader/serial monitor 

software. Often includes a debugger.

IMU: An inertial measurement unit such as the Ardu Pilot Oil Pan. Usually has at least three 

accelerometers (measuring the gravity vector in the x,y and z dimensions) and two gyros (measuring 

rotation around the tilt and pitch axis). Neither are sufficient by themselves, since accelerometers are 

thrown off by movement (i.e., they are “noisy” over short periods of time), while gyros drift over time. 

The data from both types of sensors must be combined in software to determine true aircraft attitude 

and movement to create an AHRS (see above). One technique for doing this is the Kalman filter (see 

below). Now superseded by Flight controllers which include CPU and sensors in one unit.

Inner loop/Outer loop: Usually used to refer to the stabilization and navigation functions of an 

autopilot. The stabilization function must run in real-time and as often as 100 times a second (“inner 

loop”), while the navigation function can run as infrequently as once per second and can tolerate delays 

and interruptions (“outer loop”).

INS: Inertial Navigation System. A way to calculate position based on an initial GPS reading followed by 

readings from motion and speed sensors using dead reckoning. Useful when GPS is not available or has 

temporarily lost its signal.

ICSP: In Circuit Serial Programmer. A way to load code to a microprocessor. Usually seen as a six-pin 

(two rows of three) connector on a PCB. To use this, you need a programmer, such as this one, that uses 

the SPI (Serial Peripheral Interface) standard.

Kalman Filter: A relatively complicated algorithm that, in our applications, is primarily used to combine 

accelerometer and gyro data to provide an accurate description of aircraft attitude and movement in 

real time. See this for more.

LOS: Line of Sight. See VLOS below.

LiPo: Lithium Polymer battery, aka LiPo. Variants include Lithium Ion (Li-Ion) battery. This battery 

chemistry offers more power and lighter weight than NiMh and NiCad batteries.

MAVLink. The Micro Air Vehicle communications protocol used by the Ardu Copter and Ardu Plane line 

of autopilots. See here for more info on MAVLink.

MAV: Micro Air Vehicle. A small UAV. More here.

NMEA: National Marine Electronics Association standard for GPS information. When we refer to “NMEA 

sentences”, we’re talking about ASCII strings from a GPS module that look like this: 

$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,47

Oil pan: An Arduino style shield meant to be paired with the ArduPilotMega. Contained the majority of 

the sensors (gyros, accelerometers, barometer, etc) that allow the ArduPilotMega to function as an 
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autopilot, now superseded by subsequent Flight controllers that incorporate CPU and sensors in one 

board.

OSD: On-screen display. A way to integrate data (often telemetry information) into the real-time video 

stream the aircraft is sending to the ground.

PCB: Printed circuit board. In our use, a specialized board designed and “fabbed” for a dedicated 

purpose, as opposed to a breadboard or prototype board, which can be used and reused for many 

projects.

PCM: Pulse Code Modulation: The technique some modern RC transmitters/receivers communicate the 

RC channels information. It is transmitted digitally using a digital code to represent the channel number, 

position of the transmitter stick or switch, and sometimes other information. Some modern RC systems 

also provide digital signals to control digital servos – typically specific to each manufacturer.

PDB: Power Distribution Board. A board used in multi-copters to distribute power to multiple ESCs.

PIC: Pilot in Command. Refers to a FAA requirement that UAVs stay under a pilot’s direct control if they 

are flying under the recreational exemption to COA approval. See Line of Sight above. (Not to be 

confused with the PIC processor series by Microchip)

PID: Proportional/Integral/Derivative control method. A machine control algorithm that allows for more 

accurate sensor-motion control loops and less over control. See this for more.

POI: Point of Interest. Designates a spot that a UAV should keep a camera pointed towards.

PPM: Pulse Position Modulation. The square-wave pulse train used to transmit multiple channels of 

information between some RC transmitters and receivers. Some RC receivers provide a PPM output 

(sometimes referred to as the PPM Sum) which can be used on the APM and PX4. Other receivers 

convert the PPM signal and only provide PWM signals for each channel.

PWM: Pulse Width Modulation. The square-wave signals used in RC control to drive servos and speed 

controllers. There is one PWM signal for each channel. The width varies from 1000 to 2000 

microseconds, depending on the RC manufacturer.

PX4 (PX4FMU and PX4IO): Flight Controller system providing capabilities for stabilized flight, position 

maintenance and automated mission (waypoint) path following.

RTL: Return to Launch. Fly back to the “home” location where the aircraft took off.

SiRF III: The standard used by most modern GPS modules. Includes !SiRF III binary mode, which is an 

alternative to the ASCII-based NMEA standard described above.

Sketch: The program files, drivers and other code generated by the Arduino IDE for a single project.

SVN: Short for the Subversion version-control repository used by the DIY Drones and other teams for 

source code.
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Telemetry System: A two way radio system to allow flight data to be sent from your aircraft and also to 

allow control or adjustment information to be sent back to it from a “ground station”, commonly a lap 

top computer. The 3DR telemetric radio (Here!) is one such system.

Thermopile: An infrared detector. Often used in pairs in UAVs to measure tilt and pitch by looking at 

differences in the infrared signature of the horizon fore and aft and on both sides. This is based on the 

fact that there is always an infrared gradient between earth and sky, and that you can keep a plane 

flying level by ensuring that the readings are the same from both sensors in each pair, each looking in 

opposite directions. These have been largely displaced by electronic gyros and are no longer in common 

use.

UAV: Unmanned Aerial Vehicle. In the military, these are increasingly called Unmanned Aerial Systems 

(UAS), to reflect that the aircraft is just part of a complex system in the air and on the ground. Groundbased autonomous robots are called Unmanned Ground Vehicles (UGVs) and robot submersibles are 

called Autonomous Underwater Vehicles (AUVs). Robot boats are called Unmanned Surface Vehicles 

(USVs).

VLOS: Visual Line of Sight. The pilot’s ability to see an aircraft from the ground well enough to control it, 

without the use of artificial visual aids (aside from glasses). Required by FAA regs.

WAAS: Wide Area Augmentation System. A system of satellites and ground stations that provide GPS 

signal corrections, giving up to five times better position accuracy than uncorrected GPS. See this for 

more.

Xbee: The commercial name of the recommend ZigBee-compatible radio modems commonly used by 

amateur UAVs. They can be found atsparkfun although remember you also need a board to mount it on 

like this one from sparkfun or the diy drones store.

ZigBee: A wireless communications standard, which has longer range than bluetooth but lower power 

consumption than WiFi.
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Pitfalls/Lessons Learned

Introduction

This page is intended to be a checklist of things to be sure you do at each stage of getting your copter 

into the air. These things will not prevent you from flying but could cause crashes, so it is important to 

list them all in one place for easy reading and maintenance.

Please describe the issue in as succinct a manner as possible below, and add a link for further 

information if necessary.

Assembly

 Twist all your power wires to help minimize electromagnetic interference with your 

compass: More Information!

 Check your APM is mounted in the middle of your copter, with the FORWARD arrow pointing 

straight toward the front in the intended direction of forward flight

 NEVER power camera gimbal servos from the analog output pins, you risk a brownout condition 

and your APM board rebooting More Information!

 Check each prop is secure before flying: hold the prop in one hand, the arm in the other and try 

to twist the prop loose. Don’t fly unless the props are secure.

Configuration

 Spin up the propellers on the ground and check they are all moving in the correct 

orientation More Information!

 Check that your motors are connected in the right order by using the CLI mode ‘motors’ 

command More Information!

 Hold the copter firmly, safely above your head, then spin up the propellers to 1/3rd throttle and 

test that the copter is trying to keep itself level. It should push back when you tip it over in any 

direction. Give it some left/right/up/down stick inputs and feel whether the copter is reacting in 

the correct sense to these inputs

 Check that your copter knows what level is. With the copter on a flat surface connect to Mission 

Planner and ensure the artificial horizon display shows level

 You should configure Failsafe, otherwise the default behavior is for your copter to shut down 

and fall to the ground if it loses connection with your radio transmitter. Test this by connecting 

to Mission Planner, arming your copter (with no battery connected) and turning off your 

transmitter. You should see it switch to RTL mode when the transmitter is turned off (link 

required)
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Flying

 Make sure you have a GPS lock before flying if you intend to use any auto modes. Even if you’re 

only flying in Stabilized mode this is a good idea so you can invoke Return To Launch if you get 

into trouble

 Test RTL before sending your copter off on an auto waypoint flight. This is to check that the 

compass and GPS are working, and that it knows where home is before heading off on a more 

complex flight

 Ensure that flight in Stabilize works well before you attempt any more complex flight modes. 

Ensure loiter works before trying RTL. Ensure RTL works before trying auto.

 Once armed stand 3m-6m away from the arming point as when in RTL the copter will be 

returning to this point.

 When testing more complex flight modes, be ready to switch back to Stabilize mode at any 

moment if it does anything strange. Stabilize or Acro are the only modes which can save you 

from a problem with the software or sensors. RTL is a good mode to save you from human error, 

but relies on the copter being able to locate and fly itself, so this should not be used as an 

emergency mode if other auto flight modes go wrong

 Be sure you have a way of knowing when your battery is getting low, and land before you have 

used more than 80% of your battery capacity.