Introduction
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VEX Robotics has a steep learning curve and can be hard for both new and experienced teams. We hope to provide a wealth of information here, giving every team the resources they need to build high-quality, competitive robots.
🛠
Building
💻
Coding
📗
Engineering Notebook
🏆
Tournaments
If you have suggestions or would like to contribute, let us know!
Building
Comprehensive Building Guide
CAD Design
"Measure twice, cut once"
CAD (Computer assisted design) is an essential part of VEX robotics. It allows teams to fully plan out the robot on the computer before constructing anything in the real world.
Advantages of CAD
	Disadvantages of CAD
	Plans out the robot fully ahead of time
	None
	Reduces the time it takes to build
	​
	Adds an element of professionalism to the engineering notebook
	​
	OnShape is the recommended software for CAD in VEX due to its ease of use and VEX part libraries, but other softwares work just as well.
  

Onshape | Product Development Platform
Here's a good set of video tutorial for CAD in OnShape:
​https://www.youtube.com/watch?v=8rkEL2l4pvM&list=PL58YBuL9CL7KdaFquOuCasoTzGwnjHFUN&index=1​
How to use CAD
As important as it is, CAD is not the end-all. It is a tool that you use to plan out where everything goes on the robot. However, no robot has ever perfectly matched it's CAD design, because there are more factors to consider in the real world. For example, it's not necessary to model screws in the CAD, since it is already clear where they need to be. On the other hand, important aspects of the robot--the drivetrain and additional mechanisms--should be present in the CAD, so that you know how to build them in the real world.
  

Example CAD design (Over Under). Note the extensive labelling and level of detail. We don't recommend this intake design.
Design Tips
CAD Design can be intimidating at first; here's a few tips:
* Don't be afraid to take inspiration from other robots. Watch matches online. Study reveal videos. Ask other teams questions at tournaments. If you see a design you like, imitate it--don't copy.
   * Imitate means "take inspiration from without copying screw-for-screw, and make it better along the way". It's okay to imitate other designs that work well. It's not okay to copy the entire robot, down to the last hole of the C-channels (i.e. holecounting).
* Don't overthink the positioning of the brain, battery, and air tanks. These don't have to go in the CAD design, because their positioning can usually be figured out later.
* Ask for help. Get experienced robotics members to review your CAD before you build it--this prevents you from having to take apart half of the robot to fix one minor flaw later on.
* Simpler is better. A well-optimized simple design will beat a complex one nine times out of ten. Less mechanisms means less things can go wrong on the robot, so don't overdesign!
Here's some specific tips for VEX Robotics:
* Use 2-3 cross-braces on the drivetrain that go across the entire length of the robot, preferably as far apart as possible. This prevents the chassis from bending over time (not good).
* Use standoffs everywhere! Seriously, standoffs are amazing for bracing, and come in handy when you're trying to mount a mechanism to the robot or brace something.
* Study how other successful robots mount mechanisms to the robot. There are myriads of reveal videos and robot explanations on YouTube; even looking at robots from previous years can give you ideas on how to design the structure of your robot. Imitate, don't copy.
Best Practices
Ideally durable, lightweight, and robust
In Vex, there are many techniques to getting a high-quality build. The goal is to allow the robot to last multiple competitions without breaking while keeping it as light as possible.
Triangle Bracing
Triangle bracing uses standoffs at odd angles to brace higher points on the robot. This greatly improves the stability of the higher mechanisms on the robot. In the picture below, the tower in the middle of the robot will not bend over time due to the triangle bracing.
  

For this type of bracing, we recommend using shaft collars screwed into each other and into standoffs like so:
  

Note how the shaft collars are oriented
Lighter is Better
Lighter robots move faster and can usually outscore heavy robots.
To save weight, always use the thin nylock nuts. They are about 50% lighter, which adds up when hundreds of them are used across the robot.
Additionally, always use aluminum metal to build the robot. Vex also offers steel, which is 50% stronger. However, it is also 136% heavier--not worth it.
Here's the same C-channel in both aluminum (left) and steel (right) varieties. Note the massive weight difference between the two pieces!
  

  

Center of Gravity
Ideally, the center of gravity should be two things:
* Low: prevents the robot from tipping over
* Centered: makes autonomous routines more accurate
Practically, this means that the bulk of the weight on your robot should be as low as possible. Additionally, try to have some balance in the weight distribution side-to-side. For example, mount the brain/battery and the air tanks on opposite sides of the robot to balance it out.
  

Note how all 6 drive motors and the air tank are as low as possible
Zip ties!
Zip ties are the duct tape of Vex Robotics. They work well in a pinch for meager structural support, but they don't hold up in high-stress situations. One good application of zip ties is on bearing flats for the drivetrain. That's because the bearing flats are not under any lateral stress. Additionally, this saves weight compared to the alternative (screws and nuts).
  

This should not be viable, but it is
Using zip ties instead of screws and nuts to attach bearing flats saves about 0.01 pounds per bearing flat. If you use 20 bearing flats on the robot in total, you can save 0.2 pounds of weight on the robot. Every little bit of weight reduction matters.
Bearing flat attachment method
	Weight
	Zip ties
	0.001 lbs
	Screws and nuts
	0.011 lbs
	However, zip ties should not be used for high-stress or pivotal connections, as they are prone to break over time.
Drive Trains
Unleash your inner NASCAR
Drive trains are not technically required, but nearly every robot has one. They allow the robot to traverse the field, and serve as a foundation for the rest of the the robot.
Here's the simplest possible drivetrain you can have:
  

Simple tank drivetrain CAD
This tank drivetrain features at least 2 omniwheels on each side of the robot. Usually, 4 or 6 motors will power these omniwheels either directly or through gears. This drivetrain can turn in place and go forwards and backwards, but it cannot strafe side-to-side (which is usually not necessary).
Here's another example of a more complex tank drive with 6 motors, 6 wheels, and a gear system:
  

Example drivetrain CAD
Another type of drivetrain is the X-drive. This drive has more maneuverability, but reduced torque and pushing power relative to the standard tank drive.
  

Photo credit: Team 1619Z
While the increased maneuverability does offer an advantage in niche scenarios, X-drives are very weak against defense by others teams. For example, out of the 20 teams that won their division during Spin Up Worlds (i.e. top 20 teams in the world), all 20 of them used a tank drive.
There are another couple types of drivetrains, but these are not competitively viable in VEX Robotics.
​  ​  ​
Overall, the recommended drivetrain for both new and experienced teams is the standard tank drive.
Design Guidelines
Let's assume you're going with the tank drivetrain (please do!). Here's a few general guidelines to keep in mind while designing it.
* Smaller is generally better, but don't make a drive so small that it can't fit other mechanisms on the top of the robot
* Don't use any more gears than is absolutely necessary, to reduce friction
* Have the wheels as far apart as possible, which makes it harder for the robot to tip over
* Use 2-3 cross-braces, and have them as far apart as possible. This keeps the chassis from bending under heavy defense
Here's another example CAD that follows these guidelines. Always CAD the drivetrain before building it!
  

Over Under drivetrain CAD from 96504C
Additional Resources
Here's two videos on how to square the chassis--this is very important for having consistent autonomous and a low friction drivetrain.
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Screw Joints
Screw joints are an advanced build technique that reduces friction and increases structural stability on the drivetrain, compared to using axles on the wheels.
Here's one type of screw joint:
  

Layout for one type of screw joint
Here's how to attach the gear to the wheel for this type of screw joint:
  

And here's another type of screw joint using a 2.75" wheel with a 48T gear:
Boxing
No, not that type of boxing
Boxing is an advanced build technique that improves the stability of a connection. The basic idea is to prevent a C-channel from bending by supporting it at two points rather than one. This is done with a long screw and 7/8" of spacing on the inside of a C-channel.
Here's an intake before and after boxing. In the picture to the left, the C-channel bent under heavy defense. It was fixed in the picture to the right by boxing, and the C-channel never bent again.
​  ​  ​
We also recommend boxing the cross-braces on the drivetrain as shown below. This prevents the drive C-channels from bending and makes the robot more durable.
  

Note that only the corner screw needs boxing
Bearing flats
It turns out that the square holes in vex metal pieces aren't a great fit for a rotating axle. Yes, they technically work, but the axle is highly unstable, and the friction is egregious.
  

Note the shape of the hole in the metal
The solution? Bearing flats! Bearing flats are essential for having low-friction drivetrains, and also for other mechanisms on the robot. They keep shafts aligned to the center of the hole, preventing it from touching the metal (which adds friction) or wobbling.
  

Bearing flats should be used on either side of an axle to support it and reduce friction. However, a motor also supports the axle, so there is no need for a bearing flat right next to a motor:
  

On the drivetrain, bearing flats should be used for both axle and screw joints (as possible), since they do reduce friction. For example, in the drivetrain below, the motor shafts have one bearing flat on the outside to keep the motor axle stable.
  

Note the zip ties. Yes, this works, and it works well!
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Fixing Friction
Not this again...
Friction on the drivetrain can be caused by any number of issues.
Testing Friction
Luckily, it's relatively easy to test drivetrain friction. Attach all of the gears and wheels, but not the motors and motor cartridges, like so:
  

Then, give the drivetrain a good spin with your hand, as fast as you can. The drivetrain should keep spinning for at least:
* 3 seconds, if you have axle joints
* 5 seconds, if you have screw joints
This is called the freespin time, and it's a great way to test the friction on the drivetrain. The longer the freespin time, the less friction there is.
Fixing Friction
If the freespin time on the robot is longer than acceptable, there is friction somewhere. Here's a few potential sources of friction:
Bent axles
If the drive axles are bent, then nothing else can really work. To test if an axle is bent, press it  against something you know is flat and look for a gap between the axle and the flat surface. Do this for all four sides of the axle.
  

Note the gap between the wooden table and the axle
If it is bent, then simply replace the axle and throw away the old one. There's no reason to keep bent axles around.
Tight spacing
On either axles or screws, too much spacing can cause friction issues. That's because the spacers rub against the drive C-channel, which adds resistance and extra friction. The wheel should be axle to wobble back and forth on the axle/screw by about 0.25 mm. If it can't wobble a little, then likely the spacing is too tight. Remove some of the spacers and replace them with shorter ones.
  

  

In the images above, there isn't a small gap anywhere along the axle. Thus, the spacing is too tight; this will cause friction issues. In this case, removing a washer would be the best way to fix it.
Misaligned drive C-channels
If the drive C-channels are even slightly misaligned, then that can cause friction because the axles won't be perfectly perpendicular to the inside face of the drive C-channels. Make sure to square your chassis before you start building the drivetrain to resolve this problem.
Extraneous shaft collars
Shaft collars are essential in VEX Robotics. However, there should never be shaft collars on the outside of the drive C-channels--they only cause extra friction. One shaft collar on the inside of an axle is enough to lock it in place.
Bad bearing flats
Sometimes, bearing flats go bad or can become misaligned with the holes in C-channels. If a bearing flat seems to be causing a problem, try replacing it.
Bad motor cartridges / motors
Make sure to test each motor before putting it on the drivetrain. Ideally, each motor (with the motor cartridge in) should not draw more than 0.1 - 0.2 watts of power at max speed. Use the "devices" screen on the brain to test the motor, and if it draws more than 0.2 watts of power, try to find a different motor with less internal friction. Additionally, make sure to test each cartridge as well. Bad motors and cartridges ruin a good drivetrain.
  

​
450 RPM on 2.75"
The best drivetrain
In this tutorial, we'll show you how to build a 6-motor 450 RPM on 2.75"  drivetrain, one of the best in the world. This drivetrain is fast, low-centered, and easy to build on.
We'll start with the wheel assembly.  We used 1.5” screws, ¼” spacers, and nylock nuts to connect the 48T gears to the 2.75” wheels as shown. There are two screws that go through opposite sides to balance the weight.
  

  

Next, we attached the bearing flat on the inner drive C-channel using one zip tie. That’s because the screw joint will also help to secure the bearing flat in.
  

After that, we found the best spacing for the screw joint. We used washers on both inside edges to reduce friction, and keps nuts to hold the screw joint in place.
  

Here’s how it looks when it’s all put together:
  

Before we could add the bearing flats, we had to shave down the corner of a few so they wouldn’t hit the motor caps. We used a sandpaper attachment on a Dremel and cut the corners like so:
  

Then, we attached all of the bearing flats on the inside of the drive using zip ties. The shaved upper corners of the bearing flats are circled in green.
  

Next, we attached the three motor caps using 0.25” locking screws:
  

Then, we added the rest of the wheels using the same screw joint:
  

Next, we mounted the bearing flats for the motor axles, using zip ties to save weight.
  

After that, we found the best spacing for the motor axles. Again, we used washers to reduce friction. The shaft is 3” long, and fits perfectly into the motor without sticking out past the bearing flat.
  

And with that, the left side of the drivetrain is complete!
  

We made the right side in the exact same way, except mirrored. To attach the back cross-brace, we boxed the back hole of the C-channel and attached it to a 1” standoff going up. The boxing adds extra stability and prevents the C-channel from bending.
  

We attached the rest of the cross-brace in the same manner, like so:
  

Finally, we added the front cross-brace using 0.25” locking screws and eight ½” standoffs. Two cross-braces greatly increases the stability of the drivetrain, and prevents it from bending over time.
  

With that, the drivetrain is complete!
Motors
Vroom Vroom
Motors are an essential part of VEX Robotics, as they convert the chemical energy stored in the battery into usable mechanical energy. There are two types of motors: 11-watt (11W) and 5.5-watt (5.5W) motors.
11W motors
Specifications:
* Power: 11 Watts
* Torque: 2.1 N⋅m
* Weight: 0.342 lbs or 155 grams
​  ​
5.5W motors
Specifications:
* Power: 5.5 Watts
* Torque:  1.3 N⋅m
* Weight: 0.20 lbs or 91 grams
​  ​
Each robot is allowed 88W of motor power total. Here's a table showing some possible combinations of motors that can be used on the robot:
# 11W motors
	# 5.5W motors
	8
	0
	7
	2
	6
	4
	...
	...
	Motor Cartridges
There are three types of motor cartridges for the 11W motors. Each one spins at a different RPM as shown below:
  

Hot Swapping
Hot swapping allows teams to change out broken or overheated motors for good ones without having to unscrew the motor cap (an arduous process). Hot swappable motors have rubber bands that keep the motor body secured to the motor. To make a motor hot swappable, remove the four screws that keep the motor cap secured to the motor body. Then, wrap two rubber bands around the motor as shown in the picture below. Make sure the motor is securely in place, and replace the rubber bands regularly.
  

Example hot swap
Metal
Structural stuffs
The basic structure of every VEX robot uses metal. Specifically, aluminum C-channels are used to construct the chassis and other mechanisms on the robot. These C-channels are relatively lightweight, yet still are very resistant to deformation under stress.
  

Standard 1x2x1x25 C-channel
Here's a few  other types of metal structure available:
  

5-wide C-channel
  

2x2 L-channel
  

3-wide C-channel
​
However, sometimes a C-channel is overkill for applications on a robot. By cutting a C-channel in half (the long way), you can form 1-by L-channels like the following:
  

These L-channels are good for areas of the robot that aren't under a lot of stress. That's because they're very light, but also less robust than a C-channel.
However, teams have innovated ways to use other metal pieces for support. For example, high strength shafts are exceptionally durable and highly resistant to bending. They can be attached using the shaft collars or by drilling holes through the shaft.
  

The shaft acts as a cross-brace and helps hold game objects.
Pneumatics
These pack a punch
In Vex Robotics, teams can use two things to do active mechanical work: motors and pneumatics. Pneumatics use the power of compressed air to activate mechanisms on the robot. However, each actuation uses up a little bit of air each time, so the force from pneumatics slowly decreases throughout a match. Despite this, they are very useful in a variety of mechanisms.
For example, here's a pneumatic that is used to activate wings on an VEX Over Under robot:
  

To set up a basic pneumatic system, you need three components:
* Air tank: Stores compressed air
* Solenoid: Directs compressed air
* Piston: Uses compressed air
Here's a simple pneumatic system. In summary, compressed air is stored in the air tank to the left, and then directed by the solenoid to either expand or contract the piston. The air tank is filled up with a bicycle pump or air compressor through the Schrader valve. From there, pneumatic tubing connects it to the double-acting solenoid. The solenoid directs the air to one of two output valves that lead to the two sides of the piston. Also, there's a plug in the right side of the solenoid to prevent the air from coming out of the system.
  

Simple pneumatic system setup (the new pneumatics)
For information on how to code the pneumatic system, check out this page:
🌬
Coding Pneumatics
Best Practices
Here's a few tips to keep in mind while building with pneumatics:
* Keep the air hose between the solenoid and pneumatic piston as short as possible, to minimize the amount of air lost in each actuation.
* Pneumatic pistons are designed to withstand an incredible amount of force parallel to the direction they extend in, but they are not designed to resist bending.
* Tighten each valve fitting all the way to prevent leaks. If there is a leak, and you can't find where, apply a small amount of soapy water to each valve fitting connection. If the soapy water starts to  bubble at a valve fitting, then air is leaking there.
* ​
*   * So, that's where the leak is!
Additional Mechanisms
3D Printing
Non-functional, but cool
Unfortunately, 3D-printed parts with a function are not permitted on the robot. However, you are allowed to have decorations or license plate holders that are 3D-printed.
In fact, we strongly recommend these license plate holders, because they make it very easy to change colors between matches, saving time.
  

3D printed license plate holder
Here's the file; no supports are needed when 3D printing it.
Robotics-license-plate-holder3.stl107KB
Binary
​
Ratchets
Ratchets allow certain mechanisms on the robot to only activate when a motor spins in one direction. By combining multiple ratchets, a team can add more functionality to their robot.
The basic premise of a ratchet is that a gear or sprocket is attached to a shaft such that it can spin freely around it. When the shaft rotates, the gear or sprocket does not necessarily rotate with it.
There is also a smaller gear, right next to the primary gear/sprocket that does rotate with the shaft. A small screw on the primary gear/sprocket is then rubber banded so that it "catches" on the smaller sprocket when it turns in one direction, but not in the other.
  

Outer sprocket rotates; the shaft does too
  

Outer sprocket rotates; the shaft stays still
To build a simple ratchet, first obtain and assemble the following. Note that a 6-tooth 8P sprocket will usually work for the smaller gear. Additional testing might be required to find the best spacing on the screw in the picture to the right. Also, the larger sprocket can be swapped out for a gear.
  

  

Make sure to use the circular inserts!
Now, put both of the above sprockets on the same shaft. The next step is to zip tie a small rubber band to the large sprocket, as shown below, and wrap it around the screw. This keeps the screw locked into the smaller sprocket when the axle is turning.
Catapults
Launching stuff
Catapults are a common launching mechanism. They are simple, easy to build, and quite effective at launching all sorts of game objects.
Before we can get started with catapults, we first have to go over slip gears. These are gears with either one or two sections of teeth shaved off, like so:
  

The simplest catapult possible is a slip gear directly linked to a catapult arm. The slip gear pulls back the catapult to a certain point with the teeth that are on it. Then, when the section of the slip gear with the teeth shaved off reaches the gear on the catapult, the two gears disengage. At that point, the rubber bands on the catapult launch it forwards, along with any game object on the catapult.
Here's a demonstration, courtesy of team 491A and the Purdue Sigbots Wiki:
Intakes
Intakes are mechanisms designed to pick up different game objects and put them into a robot. There are a wide variety of intakes, and we'll show you a few of them here.
The first common type of intake uses an array of flex wheels on a rotating arm. Flex wheels have a lot of grip, which makes them good at grabbing game objects. Additionally, the flex wheels can lift up and down, allowing game objects to come into the robot. Note the cross-bracing and C-channel across the intake that stabilizes it.
  

Simple Spin Up intake
Here's another example of a flex wheel intake, but this one is vertical instead of horizontal:
  

Image: 62A, BLRS wiki
Another common type of intake uses rubber bands wrapped around sprockets as shown below. Rubber bands conform to the shape of the object in the intake more than flex wheels do, which can be helpful depending on the game object and intake spacing.
  

While flex wheels and rubber band sprockets are the majority of intakes, teams can also wrap a single layer of anti-slip mat around a rubber band intake for better durability.
Lifts
No, not that kind of lift.
Lifts are any mechanism that raises one part of the robot up, usually to score points or to achieve some other purpose.
One of the most common types of lifts is the four-bar. This simple lift raises up a small bar, while keeping it parallel to it's initial position.
Another variant of the four-bar is the double reverse four-bar (DR4B). This type of lift uses two four-bars in tandem that lift the desired mechanism up even higher.
To build a four-bar, connect two C-channels in parallel as shown in the videos.


Coding
We'll use VEXcode Pro V5
Getting Started
We'll show you how to get started coding the robot using VEXCode Pro and C++
First, download VEXCode Pro and install it. Then, open the program and create a new project.
Start Coding
Let's write a simple C++ program to set up the robot:
#include "vex.h"
​
using namespace vex;
​
int main() {
   vexcodeInit(); //leave this line here! Everything else has to come after it.
  
   //prevent the main loop from exiting
   while(true) {
       wait(20, msec);
   }
}
In this code:
   * We include the necessary VEX header file, "vex.h", to access VEX V5 API functions and classes.
   * We add using namespace vex; to reference vex motors and classes natively.
   * We create the main function, which is run when the program is started.
   * We call the vexcodeInit function--always do this.
   * We use the wait function in a while loop to prevent the code from exiting before the robot can do anything
Building and Downloading Your Code
   1. 1.
   2. Connect your V5 Brain to your robot and turn it on.
   3. 2.
   4. Connect your computer to the V5 Brain using a USB cable.
   5. 3.
   6. Click on the "Download" button (at the top right) to transfer your code to the V5 Brain.
Note that the code above doesn't make the robot do anything quite yet; it is just a foundation to build on. Your first order of business should be coding the drivetrain. See this article:
🚗
Drive Code
Expanding Your Knowledge
Now that you've successfully programmed your VEX V5 robot to perform a simple task, you can expand your knowledge by exploring the VEX V5 C++ API and trying out different sensors and motor configurations. The VEX V5 C++ API documentation provides detailed information about classes and functions you can use to control your robot.
VEX V5 C++ API: vex Namespace Reference
Note: C++ is not an easy language to learn and it is often used by the most highly skilled programmers. Expect to fail many times, it is normal.
Drive Code
*Technically optional, but highly recommended
You probably want the robot to move around. However, the robot doesn't just do this on its own; you have to program it. In this tutorial, we'll show you how to do that with the double arcade control scheme--the left joystick moves the robot forward and backward, and the right joystick turns the robot.
We'll start off by adding the drive motors to the list of devices. In this example, we'll use a 6-motor drivetrain with the left and right motors plugged in to the following ports. Your port numbers can be different; all that matters is that the motors are named well and match up with the ports on the physical robot.
  

For a four-motor drive, just leave out Right3 and Left3
Now, we can start coding. For the sake of clarity, we'll put all of our drive code in a C++ function. Here's the format for a function in C++:
void driveCode() {
//drives the robot around based on controller input, double arcade controls
}
The first order of business is to get controller inputs. Make sure you have a controller listed in your devices menu:
  

Now, we can get the inputs from the joysticks and store them in integer variables. The left joystick will control forwards and backwards motion in a straight line, so we'll store that value in a variable called straight. Next, we'll store the value for the right joystick in a variable called turn, since the right joystick turns the robot. Put the following code in the driveCode() function:
//Get controller inputs
int straight = Controller1.Axis3.value(); //gives a number -100 to 100
int turn = Controller1.Axis1.value();
Now, we need to calculate the motor power, in percentage points, that we should apply to each side of the drivetrain. We'll use two variables, left and right, to keep track of the percentage motor power we will apply to the left and right sides of the drivetrain. The following code calculates motor power, and it should be in the driveCode() function, right after the previous code.
//calculate proper motor powers
int left = straight + turn * 0.7; //the 0.7 makes the turns less intense
int right = straight - turn * 0.7;
Why the 0.7?
Now that we have calculated the motor powers for the left and right sides of the drivetrain, we just have to apply that power to them. Since we have 6 motors in this example, we'll apply the motor powers to all six motors.
//Spin the drive motors at the calculated velocity
Left1.spin(forward, left, percent);
Left2.spin(forward, left, percent);
Left3.spin(forward, left, percent);
Right1.spin(forward, right, percent);
Right2.spin(forward, right, percent);
Right3.spin(forward, right, percent);
Let's put all of it together so far! Make sure to put this function before the main loop.
void driveCode() {
 //drives the robot around based on controller input, double arcade controls
  //First, get controller inputs
 int straight = Controller1.Axis3.value(); //gives a number -100 to 100
 int turn = Controller1.Axis1.value();
  //Calculate proper motor powers
 int left = straight + turn * 0.7; //the 0.7 makes the turns less intense
 int right = straight - turn * 0.7;
​
 //Spin the drive motors at the calculated velocity
 Left1.spin(forward, left, percent);
 Left2.spin(forward, left, percent);
 Left3.spin(forward, left, percent);
 Right1.spin(forward, right, percent);
 Right2.spin(forward, right, percent);
 Right3.spin(forward, right, percent);
}
Looks great! but if you add this code to your program, nothing will happen. We've made the function driveCode(), but we haven't called it yet. Now, we need to add in another function called userControl that runs when the driver controlled period in a match is active.
//driver control code, is activated when the driver control period occurs
void userControl() {
 while (true) { //run this code indefinitely
   driveCode(); //update the drive motors to be at the right power
   wait(20, msec); //don't hog the CPU
 }
}
When the controller is told to run driver control during a match, your code needs to recognize that and call the right function. Thus, we'll initialize a Competition variable at the beginning of the main file, after the using namespace vex; line.
competition Competition;
Now, update your main function to call the userControl function when the driver control period starts:
int main() {
 //Initializing Robot Configuration. DO NOT REMOVE!
 vexcodeInit();
  Competition.drivercontrol(userControl);
 //You might have more code below, leave it
 }
With that, you should have a fully functioning drivetrain! If the driving seems off, reverse directions of the the motors (try many combinations) until it works properly.
Coding Motors
In this tutorial, we'll show you how to code additional mechanisms on the robot, like an intake or catapult. Specifically, you'll learn how to spin a motor forwards and backwards at the press of a button.
First, add the motor to the devices list. In this example, our motor is named Motor
  

Next create a function that spins the motor forwards at full voltage:
//Spin the motor forward at full voltage
void spinMotorForward() {
 Motor.spin(forward, 11, volt);
}
Now, let's create another function to spin the motor backwards at full voltage:
//Spin the motor backward at full voltage
void spinMotorBackward() {
 Motor.spin(reverse, 11, volt);
}
Thirdly, we need a function to stop the motor from spinning when the button on the controller is released:
//Stop the motor
void stopMotor() {
 Motor.stop();
}
All of this code is great, but none of it will run unless we set up the proper callbacks. We'll use the buttons L1 and L2 in this example, but feel free to change it to any buttons you would like. Put the callback code in the main function, so that the controller buttons activate the functions that spin or stop the motor.
int main() {
 //Initializing Robot Configuration. DO NOT REMOVE!
 vexcodeInit();
  //Set up the motor callbacks
 Controller1.ButtonL1.pressed(spinMotorForward); //when button L1 is pressed, spin the motor forward
 Controller1.ButtonL2.pressed(spinMotorBackward); //when button L2 is pressed, spin the motor backward
​
 Controller1.ButtonL1.released(stopMotor); //when button L1 is released, stop the motor
 Controller1.ButtonL2.released(stopMotor); //when button L2 is released, stop the motor
​
 //there may be more code below, leave it be
}
Now, download the code and test to see if it works!
Coding Pneumatics
Pneumatics can be intimidating at first, but the code for them is simple. In this tutorial, we'll show you how to make a toggle button for a pneumatic piston on the robot.
Start by setting up the pneumatic in VEXCode Pro. It's a 3-wire DigitalOut device:
​  --->  ​
Now, we need to make a variable storing whether or not the pneumatic piston is current active or not. We'll use a boolean variable and set it to false by default. This variable should be defined outside of all functions, below the #include "vex.h"; and using namespace vex; lines of code.
//global variables
bool pneumaticActive = false; //true or false, whether or not the pnuematic is active
Next, we'll make a function that toggles the pneumatic piston on or off. This function flips the pneumaticActive variable first, and then either activates or deactivates the pneumatic based on the value of the pneumaticActive variable.
//toggle the pneumatic piston on or off
void togglePneumatic() {
 pneumaticActive = !pneumaticActive; //flip the on/off variable
  if (pneumaticActive) {
   Pneumatic.set(true); //Activate the pneumatic
 } else {
   Pneumatic.set(false); //Deactivate the pneumatic
 }
}
Lastly, we have to set up a callback for the togglePneumatic function, so it is run when a button is pressed. Put the following code in the main function, like so:
int main() {
 //Initializing Robot Configuration. DO NOT REMOVE!
 vexcodeInit();
  //Set up the pneumatic toggle callback
 Controller1.ButtonX.pressed(togglePneumatic);
​
 //there may be more code below, leave it be
}
That's it! Now you have code that activates and deactivates the pneumatics at the press of a button!
Advanced
More coding shenanigans
Coding Autonomous
12.5% of the match
The Autonomous period is only 15 seconds, but it can make a huge difference in matches. In this section, we'll show you how to set up code to run during autonomous.
Before we can make the autonomous program, we have to set up the code to interface with the field controllers. That is, when the controller is told to run autonomous during a match, your code needs to recognize that and call the right function. Thus, we'll initialize a Competition variable at the beginning of the main file, after the using namespace vex; line.
competition Competition;
Next, we'll make a function called autonomousProgram(). This function will contain all of the code that your autonomous will run.
void autonomousProgram(void) {   
   //insert autonomous code here
}
Now, we need to tell the controller that we want this function to run when autonomous starts. To do that, we need to add the line Competition.autonomous(autonomousProgram); immediately after the vexcodeInit() line.
int main() {
 // Initializing Robot Configuration. DO NOT REMOVE!
 vexcodeInit();
​
 // Set up callback for the autonomous period
 Competition.autonomous(autonomousProgram);
​
 //you may have more code below, leave it there
}
Now, you can simply put whatever code you would like to run during autonomous in the autonomousProgram() function, and it will run. If you want to have multiple options for autonomous, you can create multiple programs.
Coding PIDs
Worth it.
A PID (proportional integral derivative) controller is an advanced coding technique to make the robot's motion consistent, reliable, and efficient.
Theory
PIDs are used everywhere in industrial robotics--car factories, robot vacuums, and more. If a robot moves, it likely uses PIDs to move.
  

See these robots? They use PIDs
But why? PIDs do one thing, and they do it really well. They move a robot from point A to point B:
  

That's a PID. Yep, it's not that bad.
But how? This is where the PID algorithm comes in. There are three parts to a PID controller, given by the acronym. Each part applies a specific power to the drive motors based on certain factors:
   * P (Proportional): Update motor power based on the present
   * I (Integral): Update motor power based on the past
   * D (Derivative): Update motor power based on the future
What each part really does
The motor power is calculated by the following line of code, which is the heart of the PID algorithm:
float motorPower = (kP * proportional) + (kI * integral) + (kD * derviative);
That is, each part of the PID is added together to calculate motor power. kP, kI, and kD are constants that determine the relative weights of each portion of the PID.
Error
Error refers to how far the robot is from the target point. If the robot wants to go forward 20 inches, the PID algorithm would calculate the following errors.
  

Figure 3
Error plays a major factor in the PID algorithm; we'll see how later. If you want some more explanation, here's a good eight-minute video explaining the theory behind PIDs:
Now, let's start by coding your drive PID!
Drive PID Tutorial
In this tutorial, we'll show you how to code a simple drive PID--that is, moving the robot straight forward or backward. We'll use the built-in motor encoders to keep track of how far the robot has gone during the PID loop.
First of all, let's create a function called drivePID that accepts an integer variable, called driveDistance. This parameter will dictate how far the robot will go, in degrees (of the drive motors). We'll also have to make this function return the value 0 (this doesn't change anything), due to a small nuance of C++.
//Drive PID, drive the robot forward using a PID controller
int drivePID(int driveDistance) {
   //driveDistance is how far the robot should go, in degrees (of the drive motors)
​
   return 0; //Keep this line at the end of the function!
}
This function doesn't do anything yet, but it's a start. From now on, place all of the drive PID code in this function.
Remember those constants--kP, kI, and kD--that we mentioned earlier? Those become very important later on, as they make the PID effective on your specific robot. We'll put these constants at the top of the function, for the sake of organization.
//PID constants
float kP = 0.5;
float kI = 0;
float kD = 0;
You'll determine the specific values of these constants later. Keep in mind that no two robots have the same set of constants, since the weight,  speed, and drive friction vary from robot to robot; they affect these constants.
Before we get into the actual PID loop, we need to define a few more variables. These variables will be used, along with the PID algorithm, to calculate the motor power that needs to be applied to the drive motors.
//Variables for drive PID
float error = 0;      //how far the robot is from the target
float integral = 0;   //area under the error vs time graph
float derivative = 0; //slope of the error vs time graph
float prevError = 0;  //the error for the previous iteration of the PID loop
​
//Motor power variables
float motorPower = 0;     //how much power to apply to the motors, ranging from -1 (backwards at full power) to 1 (forwards at full power)
float prevMotorPower = 0; //the motor power for the previous iteration of the PID loop
At this point, we'll use a 6-motor drive in our example. We'll calculate how far the robot moves forward by taking the average of all six motor encoders. However, since the robot may have moved before the code reaches this point (from an earlier PID or such), we have to reset the position of the motor encoders back to 0:
//Reset motor encoders
Right1.setPosition(0, degrees);
Right2.setPosition(0, degrees);
Right3.setPosition(0, degrees);
Left1.setPosition(0, degrees);
Left2.setPosition(0, degrees);
Left3.setPosition(0, degrees);
Now that the setup is done, we can start coding the main PID loop. This loop does the following:
   1. 1.
   2. Gets the robot's position
   3. 2.
   4. Calculates the motor power using the PID algorithm
   5. 3.
   6. Applies the motor power to the drive motors
   7. 4.
   8. Exits if the robot is close enough to the target position
We'll create the outline of the loop, and start by calculating the current distance of the robot. We do this by taking the average position of all six drive motors. If your drive motors are set up differently, adjust your code to take the average of all drive motors or motor groups.
while(true) {
   //Calculate the current distance of the robot and store it as a number (float)
   float currentDistance = (Right1.position(degrees) + Left1.position(degrees) + Right2.position(degrees) + Left2.position(degrees) + Right3.position(degrees) + Left3.position(degrees)) / 6;
​
   wait(20, msec);//don't hog CPU, this stays at the end of the loop
}
What is currentDistance?
From now on, until told otherwise, assume all of the code goes in this while loop, after currentDistance is calculated, but before the wait function is called.
The next order of business is to calculate the robot's error--how far it is from the target. This is used to calculate the proportional term of the PID. It's simple:
error = driveDistance - currentDistance; //calculate error
After that, we have to calculate the integral term. Recall that the integral term nudges the robot the when it's close to the target, so it doesn't stall. However, due to integral windup, we don't want the integral part of the PID to come into play until the robot is close to the target. In this example, we'll only update the integral term when the robot is within 200 degrees of the final position.
Since the integral term is simply the area underneath the error vs. time graph, we can simply add the current error to the integral term. Over multiple cycles of the PID loop, it will accumulate and nudge the robot closer to the target.
if (error < 200 && error > -200) {
 integral += error; //updated the integral term if |error| < 200
}
Next, we have to find the derivative term. "Derivative" simply means "slope", so we can simply take the difference between the current error and the error in the last iteration of the loop (stored as prevError) to get the derivative term:
derivative = error - prevError; //calculate the derivative term
At this point, we can code the quintessential line of the PID algorithm! Note that "proportional" is replaced by "error" because the error is directly proportional to how far the robot is from the target.
motorPower = (kP * error) + (kI * integral) + (kD * derivative); //calculate motor power
Then, we'll clamp the motorPower variable between -1 and 1. We don't want the motors trying to spin at 150% speed.
//keep motor power between -1 and 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
One last thing before we can apply the motor power. At present, the PID algorithm will rev up the motors instantaneously at the start of the algorithm. This works, but it can cause the robot to jerk and turn slightly due to the harsh acceleration. We recommend adding a slew rate limiter, which speeds the motors up slowly rather than applying maximum power right at the start. For example, if the slew rate is 0.1, and the loop repeats every 20 milliseconds, then the robot will take 200 milliseconds (10 cycles of the loop) to increase the motor power from 0 to 1.
//slew rate limiter
float slewRate = 0.1f;
if (motorPower > prevMotorPower + slewRate) motorPower = prevMotorPower + slewRate;
if (motorPower < prevMotorPower - slewRate) motorPower = prevMotorPower - slewRate;
Now, we can apply the refined motorPower variable to the motors. We'll multiply it by 11 because the motor voltage varies from -11 to 11.
Left1.spin(forward, 11 * motorPower, volt);
Left2.spin(forward, 11 * motorPower, volt);
Left3.spin(forward, 11 * motorPower, volt);
Right1.spin(forward, 11 * motorPower, volt);
Right2.spin(forward, 11 * motorPower, volt);
Right3.spin(forward, 11 * motorPower, volt);
Next, we need to update the prevError and prevMotorPower variables, so they can be used in the next iteration of the loop.
//update "previous" variables
prevMotorPower = motorPower;
prevError = error;
All of the above code, combined, will work. But as of now, the code will keep running forever, even when the robot is at the target. Thus, we need to include a line of code that exits the PID loop once the robot is within 10 degrees of the target. You can change the number 10 to any number you would like; smaller numbers make the PID more precise, but also make it take longer. This code is called the exit condition.
//Exit the PID if the robot is within 10 degrees of the target
if (error > -10 && error < 10) {
   break;
}
That finishes up the code in the while loop. However, the motors may still be turning, even after the PID is done. To account for this, put this code after the while loop but before the end of the drivePID function:
//stop the motors when the PID is done
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
And with that, your drive PID code should be done!
But, how do you run your PID function? Call the function, passing in the number of degrees (of the drive motors) that you want the robot to go forwards for. Here's an example:
drivePID(800); //drive the robot forward 800 degrees
drivePID(-500); //drive the robot backwards 500 degrees
You can put the above code in your autonomous function.
We're not done yet, though--you'll have to tune the PID constants in order to make the PID work well for your specific robot.
Turn PID Tutorial
In this tutorial, we'll show you how to code a simple turn PID (i.e. the robot turns in place). We'll use an inertial sensor to keep track of the robot's rotation.
We'll assume you have already completed the Drive PID tutorial (you should). Thus, some steps will be simplified.
Before we get started, let's set up the inertial sensor in your devices tab. We'll name ours "Inertial",
  

Next, make sure you calibrate your inertial sensor in the main function of the robot using this line of code. This line should run when the program starts--make sure the robot is stationary for the first few seconds, so the inertial sensor calibrates correctly.
Inertial.calibrate();
Now, the PID! First of all, let's create a function called turnPID that accepts an integer variable, called turnDistance. This variable will tell the robot how far to turn, in degrees.
//Turn PID, turn the robot in place using a PID controller
int turnPID(int turnDistance) {
   //driveDistance is how far the robot should turn, in degrees (positive is counterclockwise)
​
   return 0; //Keep this line at the end of the function!
}
This function doesn't do anything yet, but it's a start. From now on, place all of the turn PID code in this function.
Next, let's add in our PID constants.
//PID constants
float kP = 0.05;
float kI = 0;
float kD = 0;
Before we get into the actual PID loop, we need to define a few more variables:
//Variables for turn PID
float error = 0;      //how far the robot is from the target, in degrees
float integral = 0;   //area under the error vs time graph
float derivative = 0; //slope of the error vs time graph
float prevError = 0;  //the error for the previous iteration of the PID loop
​
//Motor power variables
float motorPower = 0;     //how much power to apply to the motors, ranging from -1 (clockwise at full power) to 1 (counterclockwise at full power)
float prevMotorPower = 0; //the motor power for the previous iteration of the PID loop
One last thing--we need to keep track of the inertial sensor's initial position, so we know how far the robot has turned compared to it's rotation before the PID runs. We'll define a variable called startDistance to keep track of this.
float startDistance = Inertial.rotation(degrees); 
Now that the setup is done, we can start coding the main PID loop. We'll start by calculating the current distance of the robot. We do this by taking the difference between the robot's current position and its starting position.
while(true) {
   //Calculate the current distance of the robot and store it as a number (float)
   float currentDistance = startDistance - Inertial.rotation(degrees);
​
   wait(20, msec);//don't hog CPU, this stays at the end of the loop
}
What is currentDistance?
From now on, until told otherwise, assume all of the code goes in this while loop, after currentDistance is calculated, but before the wait function is called.
The next order of business is to calculate the robot's error--how far it is from the target. This is used to calculate the proportional term of the PID.
error = turnDistance - currentDistance; //calculate error
After that, we have to calculate the integral term. We'll only activate it when the robot is within 10 degrees of the target position, to avoid integral windup.
if (error < 10 && error > -10) {
 integral += error; //updated the integral term if |error| < 10
}
Next, we have to find the derivative term. "Derivative" means "slope", so we can simply take the difference between the current error and the error in the last iteration of the loop (stored as prevError) to get the derivative term:
derivative = error - prevError; //calculate the derivative term
At this point, we can add the quintessential line of the PID algorithm! Here it is:
motorPower = (kP * error) + (kI * integral) + (kD * derivative); //calculate motor power
Then, we'll clamp the motorPower variable between -1 and 1.
//keep motor power between -1 and 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
Next, we'll add the slew rate limiter to prevent jerky robot motion.
//slew rate limiter
float slewRate = 0.1f;
if (motorPower > prevMotorPower + slewRate) motorPower = prevMotorPower + slewRate;
if (motorPower < prevMotorPower - slewRate) motorPower = prevMotorPower - slewRate;
Now, we can apply the refined motorPower variable to the motors. We multiply it by 11 because the motor voltage varies from -11 to 11. Note that the motorPower is multiplied by -11 for the left drive motors, so the robot turns in place instead of driving forward.
Left1.spin(forward, -11 * motorPower, volt);
Left2.spin(forward, -11 * motorPower, volt);
Left3.spin(forward, -11 * motorPower, volt);
Right1.spin(forward, 11 * motorPower, volt);
Right2.spin(forward, 11 * motorPower, volt);
Right3.spin(forward, 11 * motorPower, volt);
Next, we need to update the prevError and prevMotorPower variables, so they can be used in the next iteration of the loop.
//update "previous" variables
prevMotorPower = motorPower;
prevError = error;
All of the above code, combined, will work. But as of now, the code will keep running forever, even when the robot is at the target. Thus, we need to include a line of code that exits the PID loop once the robot is within 1 degree of the target. Feel free to tune the exit condition, but within 1 degree is a pretty good baseline.
//Exit the PID if the robot is within 1 degree of the target
if (error > -1 && error < 1) {
   break;
}
That finishes up the code in the while loop. However, the motors may still be turning, even after the PID is done. To account for this, put this code after the while loop but before the end of the turnPID function:
//stop the motors when the PID is done
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
And with that, your turn PID code is done! We're not finished yet, though--you'll have to tune the PID constants in order to make the PID work well for your specific robot.
Tuning PIDs
Perseverance makes perfect
At this point, you should have coded the PIDs fully. Now, you have to tune those three constants to make the PID work well on your specific robot. Here's a quick recap of each constant:
   * Proportional (kP): if the robot is far from the target, set the motor power high so the robot gets there faster. If the robot is close, set the motor power low so the robot doesn't overshoot.
   * Integral (kI): if the robot is close to the target, but not quite there, increase the motor power over time so the robot doesn't stall.
   * Derivative (kD): if the robot is rapidly approaching the target, apply the brakes so the robot doesn't go too far.
Remember, everything on the robot--drivetrain friction, gear ratio, weight distribution, center of gravity--influence the optimal PID values for the robot. That is, you might have to re-adjust the PID values if something major changes on the robot.
Let's say we're tuning the drive PID (the process is the same for the turn PID). We started with these values. Try out the drive PID. How well does it work?
//PID constants
float kP = 0.5;
float kI = 0;
float kD = 0;
Why are kI and kD both 0?
If the robot barely moves, try increasing kP--this increases the motor power applied. If the robot jerks forward and goes too far, try decreasing kP.
Your goal should be the green line in the graph below, where the robot reached the setpoint (target) quickly and stays there. The graphs represent's the robot's current distance, compared to the target; this applies to both turn PIDs and drive PIDs.
  

Source: OscarLiang.com
If your robot acts like the orange line on the graph above, where the robot goes past the target and  reverses direction, consider adding in the kD term. As a starting point, set this term to 5 times the value of the kP term. Adding in the integral term (start at about 1/10th the value of kP) may also help.
If your robot acts like the blue line on the graph above, where the robot takes a while to reach the target, increase kP or decrease kD.
These rest of PID tuning comes down to trial and error; it's your job to find the set of values that works best for your specific robot.
If you want a more mathematical approach to estimating kP, kI, and kD from the start, take a look at this page:
Ziegler-Nichols Method
Advanced coding shenanigins...
The Ziegler-Nichols method is a simple way to estimate decent values for kP, kI, and kD. These estimates are a good starting point for manual tuning.
We need two numbers before we can run this method:
   * Ku, the critical (or ultimate) gain
   * Tu, the period of the oscillations at the critical gain
That is, Ku is the minimum value of kP for which the robot will oscillate steadily around the target. To find it, slowly increase kP until the robot wobbles consistently across the target. Then, find Tu by taking a video of the robot oscillating, and find the period, in seconds, of the oscillation. The period is how long it takes the robot to go from one side of the target, to the other side, and then back again.
Once you've found Ku and kP, you can then calculate the estimated values of kP, kI, and kD using a few equations, as shown in this PID calculator:
Alternate Link: https://html-7159868.codehs.me/pid.html​
​
A small technicality
Graphing PIDs
Graphing PIDs can be helpful when tuning them; it gives you a good idea of how quick and accurate the PID is.
In the graph below, the green line shows how far the robot is from the target point. The robot starts off far from the target point, but reaches it by the end of the graph. The orange line is the motor power, which initially increases sharply, but then decreases when the robot gets close to the target point so it doesn't overshoot.
  

Here's our simple graph
First of all, make sure you include a few libraries at the top of the main file.
#include <cmath> 
#include <vector>
#include <cstdlib>
Next, here's the main graphing function. It clears the brain screen and draws a graph displaying the robot's progress towards the target, and the motor power too.
//graphing data, used for PID tuning
void graphPID(std::vector<int> errorHistory, std::vector<float> powerHistory, int goal, float error, int time) {
 //goal is the PID goal (driveDistance)
 //error history is a list of all of the errors (range is 0 to driveDistance)
 //powerHistory is a list of the power applied (range is -1 to 1)
 //error is the current error
 //time is the current time, in milliseconds
  //Setup: clear screen and draw the target line
 Brain.Screen.clearScreen();
 Brain.Screen.setPenWidth(2);
 Brain.Screen.setPenColor(white);
 Brain.Screen.drawLine(0, 60, 480, 60);
 Brain.Screen.setPenWidth(1);
 Brain.Screen.setPenColor(green);
​
 //display final error and time
 Brain.Screen.setCursor(1, 1);
 Brain.Screen.clearLine(1);
 Brain.Screen.print(" Final Error: ");
 Brain.Screen.print(error);
 Brain.Screen.print("    Time: ");
 Brain.Screen.print(time);
  //define the borders of the graph
 int minY = 60; //error = 0 (robot is at target)
 int maxY = 230; //error = driveDistance (Robot is at start)
 int minX = 10; //time = beginning
 int maxX = 470; //time = end
  //loop through each data point and graph it
 for (int i = 0; i < errorHistory.size() - 1; i++) {
   int x = minX + (maxX - minX) * i / errorHistory.size(); //find the x-value of this data point
  
   //graph velocity
   Brain.Screen.setPenColor(green);
   Brain.Screen.drawLine(x, minY + (float)errorHistory.at(i) / goal * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), minY + (float)errorHistory.at(i + 1) / goal * (maxY - minY));
  
   //graph power, changing color based on direction
   if (powerHistory.at(i) > 0) {
     Brain.Screen.setPenColor(orange);
   } else {
     Brain.Screen.setPenColor(yellow);
   }
  
   Brain.Screen.drawLine(x, maxY - std::abs(powerHistory.at(i)) * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), maxY - std::abs(powerHistory.at(i + 1)) * (maxY - minY));
 }
}
We've made the graphing function; now we just have to call it. But first, we need to log the error history and power history in the PID function. Put this code in the PID function, before the while loop.
//lists
std::vector<int> errorHistory; //keep track of error over time
std::vector<float> powerHistory; //keep track of motor power over time
int currentTime = 0; //keep track of time over time (wow!)
Next, we'll update the history vectors with the current values, and then call the function. Put this code in the PID function while loop, before the wait(20, msec); line:
//update histories and current time
errorHistory.push_back(error);
powerHistory.push_back(std::abs(motorPower));
currentTime += 20;
​
//graph the PIDs
graphPID(errorHistory, powerHistory, driveDistance, error, currrentTime);
And with that, you should have a working graph while your PIDs are running! This graph can be used to make tuning the PIDs much easier, as it allows you to see the exact path of the robot to the target point.
Tasks
Multithreading made simple
Tasks allow the code to execute multiple functions simultaneously. For example, one task could handle the driving inputs, and another task could spin a catapult or flywheel at the same time.
Tasks themselves are functions that return an integer (it's C++, go along with it). You can put whatever code you want inside of it, but usually there's a while loop so actions within the task execute more than once. Here's a basic task (called myTask) that spins a flywheel forward:
int myTask() {
 while (true) {
   //do something here
   Flywheel.spin(forward); //just an example
   wait(25, msec);
 }
  return 0; //C++ technicality
}
Tasks can be created with this line of code, and will not run until they have been created. The variable spinFlywheel stores the task internally for future reference.
task spinFlywheel = task(myTask);
If you want the task to stop running, call the stop() function on it:
spinFlywheel.stop();
We recommend using tasks for controlling lifts, catapults, or flywheels when the control algorithm required is non-trivial.
Advanced Drive Code
A more intuitive driving experience
While the basic split arcade drive does work, we'll show you a small addition to the code that can make the driving experience more intuitive. This code simply adjusts the turns to be more intense when the robot is going faster.
void driveCode() {
 //drives the robot around based on controller input, double arcade controls
  //First, get controller inputs
 int straight = Controller1.Axis3.value(); //gives a number -100 to 100
 int turn = Controller1.Axis1.value();
  //adjust the turn variable based on the straight one
 if (forward1 > 50) {
   turn *= (((forward1 - 50) / 50) + 1);
 } else if (forward1 < -50) {
   turn *= (((-50 - forward1) / 50) + 1);
 }
  //Calculate proper motor powers
 int left = straight + turn * 0.7; //the 0.7 makes the turns less intense
 int right = straight - turn * 0.7;
​
 //Spin the drive motors at the calculated velocity
 Left1.spin(forward, left, percent);
 Left2.spin(forward, left, percent);
 Left3.spin(forward, left, percent);
 Right1.spin(forward, right, percent);
 Right2.spin(forward, right, percent);
 Right3.spin(forward, right, percent);
}
This was adapted from https://wiki.purduesigbots.com/software/competition-specific/curvature-cheesy-drive​


Engineering Notebook
Technical documentation
The engineering notebook is the pièce de rèsistance of a VEX team. From the engineering notebook, one should be able to follow the entire design process of a team. At a basic level, the notebook should have:
   * Analysis of the game
   * Possible designs
   * Selection of the best design
   * Step-by-step documentation of the building process
   * The full code for the robot
   * Testing and test results
   * Project management notes
In this section, we will be using team 96504C's Spin Up notebook as an example. While this notebook did earn 4 Excellence Awards, it is not a perfect notebook. Still, it's a good starting point.
Formatting
For the Engineering Notebook
There are many programs that can be used to create Engineering Notebooks: Google Docs, Google Slides, Word, Notion, etc. We recommend Google Docs because it is easy to collaborate with others, but any word processor will work. For competitions, print out the notebook and put the pages in a 3-ring binder.
Here's an example of a well-formatted notebook page. The green annotations highlight the good aspects of this notebook page
  

Team 96504C's budgeting page. Some ideas adapted from 515R
Some of the important elements of every notebook page:
   * Header / footer with section number
   * Header / footer with page number
   * Digital signatures with dates of contribution
Additionally, make sure to include a table of contents at the beginning of the notebook, so that it's easy to find sections in the notebook. See the next page, "Notebook Walkthrough" for more information.
Notebook Walkthrough
Step-by-step notebook guide
We'll go through most of the notebook sections you should include, with examples. Every page of the notebook should make it easier for the judges to give your team a perfect score on the notebook rubric.
Here's the notebook rubric, for reference: https://roboticseducation.org/documents/2023/06/guide-to-judging.pdf/#page=38&zoom=100,44,62​
________________


Introductory Pages
These should go at the front of your notebook; they organize and propel the rest of the notebook.
Title Page
The title page should prominently feature the team name, number, and logo (if you have one). This allows the judges to easily identify which notebook is yours and makes it more memorable when they are distributing awards.
  

Simple title page
Table of contents
The table of contents organizes the rest of the notebook. When appropriate, each entry should be color-coded based on the Engineering Design Process. For example, the game introduction falls under the "ask" step, so it's colored red in the table of contents below. There are a number of ways to format the table of contents itself, but it should be clear when each entry was made and what step of the Engineering Design Process it shows.
  

Example table of contents from team 96504C. Some formatting adopted from team 96504P
Engineering Design Process
The Engineering Design Process is the essence of VEX Robotics. Thus, a brief description of the process, in the form of a graphic or text, should be included in the notebook. Make sure to cite your sources for images that are taken from another website!
  

Cite your sources!
Team Profile
After the Engineering design process, you should include a brief description of the team. This helps the judges match faces to teams, and makes your notebook more memorable. For a great example of a team profile (and other good notebook advice), check out https://wiki.purduesigbots.com/team-administration/team-documentation/how-to-start-a-notebook/segments-of-the-notebook#the-team​
Notebook Formatting
Next, we recommend including a page about how the notebook is formatted. This should give the judges a basic idea of how the notebook is set up, and allow them to navigate and grade the notebook quickly.
  

Google docs has version history tracking! Use that or something similar to verify dates of contribution
Goals
The goals section can be very short, but your team should outline a few targets to reach. A few example goals:
   * Qualifying to States / Worlds
   * Winning a tournament
   * Learning a new programming technique
   * Building a low friction drivetrain
GANTT Chart
A GANTT chart is a simple, concise, and effective time management tool. It gives a rough outline of how much time should be allocated to each aspect of robotics and demonstrates advanced time management skills. Here's an example early-season GANTT chart:
  

Budget
Following 515R's example, we recommend including a budgeting page at the beginning of the notebook. This will help your team to get a realistic estimate of the financial resources necessary to compete at the level you want to. Again, this shows the judges that your team can manage the project diligently and effectively.
  

Why the pie chart? Because it looks nice and conveys information effectively
Content Pages
These pages make up the bulk of the notebook; they document the designing, building, testing, and refining of the robot and game strategy.
Game Analysis
The game analysis section has four main goals:
   1. 1.
   2. Describe the goals of the game and how to score points
   3. 2.
   4. Document the specifications of field and game elements
   5. 3.
   6. Discuss the game rules in-depth
   7. 4.
   8. Determine which game strategies are viable
Describe Goals
The engineering notebook rubric states that teams must:
Identify the game and robot design challenges in detail at the start of each design process cycle with words and pictures. State the goals for accomplishing the challenge
Thus, it is important to explicitly lay out the goals for the game. Here's a simple example for VEX Over Under:
  

Document Specifications
Next, make sure to identify the dimensions of each field element and game piece. This will come in handy later, during the designing phase. Here's an example of the goal dimensions in Over Under.
  

Discuss Rules
After that, describe the specific rules of the game. We recommend giving a broad overview of the scoring and penalty rules, then summarizing each specific game rule.
  

Concise summaries of three specific game rules. Use your words, not the game manual's!
Determine Strategies
Then, list out some of the potential strategies that might be viable. This will help with the designing of the robot later on, as it shows you which aspects of the game are the most important. We analyzed 7-8 different strategies in Over Under; here's a small snippet:
  

The Advantages / Disadvantages tables are adapted from team 515R's notebook
Design Constraints
While not technically required by the rubric, adding a short and sweet section on the basic design constraints in VEX adds an element of completeness.
  

Not a complete list, but a good starting point
Brainstorming
This is where your team generates possible designs for the robot.
The Engineering Notebook Rubric states that the notebook should
List three or more possible solutions to the challenge with labeled diagrams. Citations provided for ideas that came from outside sources such as online videos or other teams.
Each subsystem of the robot should have at least three unique designs, in order to earn full credit on the rubric. Each design should include a full CAD (or at least a detailed drawing), as well as labels for each aspect of the design. Then, explain the design and list the advantages and disadvantages of it. Here's an example page showcasing a possible design for the drivetrain:
  

Give credit where credit is due! Note the small text underneath the table
Planning
At this point, your team should have analyzed the game and identified three possible designs for each subsystem of the robot. But how do you know which design you should build?
That's the purpose of a decision matrix; it determines the best design by comparing each design's strengths and weaknesses. Testing also works, but the decision matrix is more efficient.
The Engineering Notebook Rubric says that the notebook must:
Explain why the solution was selected through testing and/or a decision matrix. Fully describes the plan to implement the solution.
Here's an example of a decision matrix for the drivetrain. Make sure to explain each criteria in the decision matrix. See the page on decision matrices for more information on how to make one.
  

Furthermore, make sure to fully describe the plan to implement the solution. The plan doesn't have to be extremely detailed or complex, but it does have to be there.
  

Building
Now, it's time for the fun part! Once you've determined the best design, it's time to build it!
According to the Engineering Design Rubric, the notebook should:
Record the steps to build and program the solution. Includes enough detail that the reader can follow the logic used by the team to develop their robot design, as well as recreate the robot design from the documentation.
That is, the notebook should include enough detail that anyone could re-create the exact robot just from the notebook and the materials used. Label images as much as possible, and make sure to explain every last screw on the robot and why it is there. Here's an example of a page detailing how part of an intake was built:
  

A picture is worth a thousand words
It's worth noting that you should also include the full code of the robot after every major revision. When only a small part of the code changes, only include that bit of code, and make sure to describe what changed and why.
Here's a small snippet of a main loop, in C++
  

Example code
Testing
Does the robot work? Well, there's only one way to find out. Test it!
The Engineering Notebook Rubric is very clear; the notebook should
Record all the steps to test the solution, including test results.
There's a lot of freedom in terms of how you decide test the robot. Of course, the tests should be a valid measure of the effectiveness of the robot or subsystem. Here's an example of a drivetrain test:
  

Short and sweet
Tournament Analysis
Tournaments are a great way to stress-test the robot under intense gameplay. After each tournament, your team should analyze:
   * How and why the robot malfunctioned
   * Number of points scored from each element of the game in each match
   * Other robot designs and strategies that worked well
Here's an example of how to document the problems the robot encountered:
  

Be specific--the purpose of this is to allow you to fix these things later on so it doesn't happen again
Here's an example of scoring analysis from Spin Up. Note how we kept track of how we scored points, which allows us to see our strengths and weaknesses.
  

Scoring analysis
Here's an example of how to analyze other strategies (for Spin Up):
  

Again, be specific and thorough when analyzing strategy
Design Process
At some point in every team's season, they will realize that their current robot simply will not do. Then, they are forced to redesign and start from scratch.
The Engineering Notebook Rubric is well aware of this fact; one of the requirements is
Show that the design process is repeated multiple times to improve performance on a design goal, or robot/game performance.
Thus, a redesign has to be properly justified in the notebook. Perhaps the robot needs a faster drivetrain or a smaller chassis, so it can navigate the field faster. Or maybe the other mechanisms on the robot can be replaced with something better. Whatever it is, make sure the notebook explains why the new design will be better than the old one.
Here's an example of a redesign justification from Spin Up:
  

Show that the new design is better--because it is!
Project Management
This part of the notebook is intuitive, but often overlooked or implemented inconsistently. For each meeting, there should be set goals, and the notebook should evaluate whether or not the team met those goals at the end of the meeting. Additionally, the notebook should keep track of time and resource constraints that are relevant to the team.
The Engineering Notebook Rubric puts it this way:
Provides a complete record of team and project assignments; team meeting notes including goals, decisions, and building/programming accomplishments; Design cycles are easily identified. Resource constraints including time and materials are noted throughout.
There are a couple of ways to do this; we recommend setting 2-4 goals per meeting and evaluating the meeting at the end. For example, here's the very first part of a meeting entry:
  

And here's the corresponding summary at the end of the meeting:
  

Note how this notebook also sets a tentative goal for the following meeting--that's time management!
Other Notebook Requirements
We've covered 90% of the notebook, but there are a couple more requirements to keep in mind (based on the Engineering Notebook Rubric). Here's the first one:
Team shows evidence of independent inquiry from the beginning stages of their design process
This simply means that teams should take initiative and test their own designs, instead of simply copying from another team online.
The next requirement refers to the completeness of the notebook:
Records the entire design and development process in such clarity and detail that the reader could recreate the project’s history.
That is, every aspect of the designing, building, coding, and testing of the robot should be included in the notebook so well that anybody could build the exact robot using only the notebook as a guide.
The last requirement is why all of the example notebook pages have dates and signatures (yes, they were redacted) in the footer of each page:
Five (5) points if the notebook has evidence that documentation was done in sequence with the design process. This can take the form of dated entries with the names of contributing students included and an overall system of organization. For example, numbered pages and a table of contents with entries organized for future reference
See the "Formatting" article for a good example of how to incorporate digital signatures in the notebook.
Conclusion
That's it! Follow all of the above steps, and your notebook will shine!
Decision Matrices
Every choice is a decision matrix
Decision Matrices are the best way to make decisions. Which house to buy? Which classes to take? Which college to attend? All of these choices can be analyzed using decision matrices. In Robotics, decision matrices are primarily used to select the best design from multiple candidates.
A decision matrix has two lists:
   * A list of possible designs along the top row
   * A list of criteria to evaluate the designs along the left column
Each design is given a score from 1-5 for each criteria. Then, the weighted total is calculated; it's the sum of each criteria score multiplied by its weight.
Criteria:
	360 RPM Tank Drive
	X-Drive
	Tank Tread Drive
	Maneuverability
Weight: 3
	4
	5
	2
	Robustness
Weight: 2
	4
	3
	2
	Simplicity
Weight: 1
	5
	1
	3
	Weighted totals:
	25
	22
	13
	For example, here's how we calculated the weighted total for the 360 RPM Tank Drive in the above matrix:
   * Maneuverability: 3 * 4 = 12
   * Robustness: 2 * 4 = 8
   * Simplicity: 1 * 5 = 5
Weighted total: 12 + 8 + 5 = 25
The other weighted totals are calculated using the same method; the design with the highest weighted total is the best one.
​
Decision Point
The point of decision
Decision points are critical junctures where choices impact your robot's design and performance. Decision matrices are your trusty tools here. These are key moments where you must choose between different paths, like prioritizing speed or utility.
Steps:
   1. 1.
   2. Identify Decision Points: Recognize moments demanding a choice, e.g., choosing intake mechanism.
   3. 2.
   4. Create a Decision Matrix: List designs and criteria. For an intake mechanism, criteria could include intake speed, capacity, and distance launched.
   5. 3.
   6. Evaluate Designs: Rate each design against criteria, considering factors from 1 to 5, with 5 being the best.
   7. 4.
   8. Calculate Totals: Apply weighting factors to criteria. The design with the highest total score is your choice.
It is important to note that when your team comes to a decision point you need to make a decision, otherwise you lose on valuable time. You should allot a certain time frame in the decision making process to set limits on how long you are willing to spend on coming up with a decision to avoid time wastage.
If your team is still unable to come up with a decision within the allotted time, it is the captain's job to make the decision. This may sound like it cuts out feedback from other members, but this is the wise choice since there was previously an allotted time where all members could give their input on the choice to make but that didn't result in a consensus. This makes an executive decision the ideal choice to make sure the team's workflow remains on track.
​




Additional Resources
Here's some more great resources to help your team get started on the notebook

Segments of the Notebook
BLRS Wiki

Format of an Engineering Notebook
VEX Forum
​


Tournaments
Trial by fire...
Filming Matches
But why?
You should film every match. Why? Because later, after the tournament, you will:
   * Analyze why and how the robot broke or malfunctioned
   * Reflect on your team's game strategy and compare it to other strategies
   * Study other team's effective robots and game strategies
There are 120 seconds in a match--15 for autonomous, 105 for driver control. Examine the videos carefully; did you waste a single second? What can be improved on the robot? Do you need more driver practice?
Yes, that's a high standard. That's what it takes to win. Don't waste a single second.
Team Interviews
The interview is just as important as the notebook for winning judged awards at VEX Tournaments. A good interview is professional, clear, and concise.
Interview Tips
To ace the interview, you need to know the ins and outs of what they will ask. You can learn more about what the judges will be looking for by checking out Interview Scoring.
⛳
Interview Scoring
But, success requires knowing more than just what is on there, it requires knowing how to approach it as well. Here are some interview tips for success:
   1. 1.
   2. Delegate each teammate to a specific part of the rubric. Doing this allows for a clean organization of who will say what during the interview, and will reduce teammates talking over each other, which can cost you points
   3. 2.
   4. Not every teammate has to be at the interview. If not all teammates are comfortable with the interview or if you have a big team, not everybody needs to be present at the interview since all present members are expected to contribute meaningfully to the interview process, which can be hard if there are too many or are uncomfortable with it.
   5. 3.
   6. Focus on what makes you stand out. The interview is also a time to show what makes your team unique from the others, so if you have an unorthodox method of solving a problem make sure to emphasize why you chose that method and why your team uses it.
   7. 4.
   8. Don't get stressed. Remember, this isn't a job interview where you'll be asked questions you don't know the answer to. This is a robotics interview so everything will be about robotics, so if you know how your robot works you will be fine.
   9. 5.
   10. Keep track of time since the interview only lasts 10 minutes. You can have a great interview without using all the time but if you run out of time you could potentially miss out on the 8 rubric points given. Be sure to keep a rough outline of how much time you will allot to different components of your robot and design.
   11. 6.
   12. Don't be afraid to let your personality shine. The interview is your team's chance to stand out from the rest of the competitors and show what is unique about you and your team that the robot can't show. Just make sure you keep it in control and the conversation still covers what is needed for the points in the rubric.
Interview Scoring
Interviews are scored based on the following rubric, taken from the VEX Judging Guide:
  

Interview Rubric
Let's go through each of the categories:
   1. 1.
Engineering Design Process - The engineering design process is the backbone of robotics and is critical to success. To get a good score, you need to show definitive proof that you used this process in your notebook and you can explain how you used it to make your robot.
   2. You can learn more about the engineering design process here: https://vrc-kb.recf.org/hc/en-us/articles/9628278280215-VRC-Engineering-Design-Process​
   3. 2.
   4. Game Strategies - To gain this point you need to showcase that you came into this competition with a plan on how you were going to play and what factors affected this plan and how.
   5. 3.
   6. Robot Design - This one goes a bit hand in hand with the engineering design process and shows that your team actually utilized it in the building of the robot. To get this point, you need to showcase how you got from your initial robot design to your current robot design and how and why the design changed.
   7. 4.
   8. Robot Build - To gain this point, you have to show that you are knowledgeable about your team's bot and know its ins and outs. To earn this point, you will need to be able to answer any questions the judges might have about your robot's build and parts.
   9. 5.
   10. Robot Programming - This one follows the same pattern as the build, where you need to be able to explain in depth how your robot's programming works to earn the point.
   11. 6.
   12. Team and Project Management - To earn this point you need to show that you took measures to keep your team operations on track and managed the project properly to maintain optimal efficiency
   13. 7.
   14. Teamwork, Communication, Professionalism - To earn this point, your team needs to perform well in the interview itself. This can be done by avoiding talking over one another, communicating clearly with confidence, and being professional. More importantly, every team member must contribute meaningfully to the interview questions being asked.
   15. 8.
   16. Respect, Courtesy, Positivity - This point comes from your attitude during the interview. If your team is doing the interview with positivity, interest, and respectfulness, you will earn the point.
Interview Practice Questions
Practice makes perfect
To sharpen your team's interview skills, you can try out some practice questions to test if your team is well prepared. This is not an exhaustive list, but it's a good start.
Most Common Questions:
   * What are your roles/jobs on the team?
   * How did you develop your robot design?
   * What part of your robot are you most proud of? Why?
   * Did you use any sensors? What are they used for?
   * Has your game strategy been effective? How and why?
Other Questions:
   * What does your robot do and how does it score points?
   * What were the challenges you identified before designing your robot? How did you design your robot to meet those challenges?
   * Which team members built the robot?
   * Were there any other robots that inspired your robot design? How?
   * How do you manage your time?
   * How do you manage your resources?
   * What changes did you make to improve your design during the season?
   * What iteration/version of your robot is this?
   * What was the most difficult challenge your team has overcome so far?
   * What problems did you have in working on your robot? How did your team solve them?
   * If you had one more week to work on your robot, how would you improve it?
   * How has your strategy changed over the course of the season?
   * Tell us about your robot’s programming – who was the primary programmer?
   * What were the challenges of this year’s game that you considered before designing your robot? How did you design your robot to meet those challenges?
   * What are your goals for Driver and Autonomous Coding Skills scores? What are your average scores?
Skills
Your path to States and Worlds
Skills is perhaps the most important part of any robotics competition, at least for new teams. There are two types of Skills runs:
   * Driver Skills: The driver gets one minute (1:00) to score as many points as possible on the field
   * Programming Skills: A program has one minute (1:00) to score as many points as possible on the field
At every competition, you get three Skills attempts for each type of run. Your total Skills score is the sum of your best driver run and your best programming run. Even more, get your skills runs in early! Don't wait until the last minute--the line usually gets extra long near the end.
But why does it matter?
Well, skills rankings are the best indicator of a team's true skill level--that's because the randomness of qualification matches can cause even the best teams to rank poorly. However, Skills is only dependent on your team.
Because of this, VEX uses Skills to award qualifications to teams for extra spots at States and Worlds. For example, when there are any extra spots left over in the State tournament, the remaining spots are awarded to the highest unqualified teams on that state's Skills rankings. That means it's relatively easy to qualify to state; you just have to run Skills and do decently well.
The same thing applies for Worlds. When a team qualifies twice for Worlds (at States), then the extra Worlds spot is awarded to the highest unqualified team on the States Skill rankings. This is, by far, the best way to qualify to Worlds. At TN States in 2023, all teams that ranked at least 16th in Skills qualified to Worlds.
In conclusion, do Skills--you won't regret it.
Ranking and Stats
Who's the best?
In tournaments, VEX Via reports a number of statistics: WP, AP, SP, OPR, DPR, and CCWM. These can seem confusing at first, but we'll go over what each one means here.
  

This is from Haunted 2023
Ranking Stats
These determine your overall ranking going into Alliance selection.
WP (Win points)
Win points are the primary factor when it comes to determining the rankings of a team. Winning a match earns you 2 win points and tying a match earns you 1 win point. Additionally, the Autonomous Win Point (AWP) gives you a single win point.
AP (Autonomous points)
Autonomous points reflect how many times your team earned the Autonomous bonus in your matches. If two teams have the same number of win points, the team with a higher AP will be higher in the rankings.
SP (Strength of schedule points)
Strength of schedule points reflect how good your opponents are, since it's the sum of the losing alliance's score for all of your matches. A higher SP means you've faced tougher opponents; for this reason, it's the second tiebreaker if WP and AP are the same.
Fun Stats
The usefulness of these stats can vary from year to year, but they're always fun to look at.
OPR (Offensive power rating)
A team's offensive power rating is their calculated contribution their alliance's scores, by a mathematical model. A high OPR means that team is good at scoring points in matches; higher is better.
DPR (Defensive power rating)
A team's defensive power rating is their calculated contribution the opposing alliance's scores, by a similar mathematical model. A low DPR means that team is good at keeping the opposing alliance's score low; a lower DPR is better.
CCWM (Calculated contribution to win margin)
A team's CCWM is simply their OPR - DPR. This gives a fairly good estimate to how much they contribute in matches. A team with a high CCWM is good; a team with a low CCWM may have won most of their matches, but perhaps they had good alliance partners. Thus, higher is better.


Management
Where business and Robotics collide
Team Management
In order to succeed, a good team is essential.
Delegation
Delegating team members is crucial to success, productivity, and optimal performance.
In a team there are a few roles you can designate to team members:
   * Captain
   * Driver
   * Analyst
   * Programmer
   * Designer
   * Builder
   * Tester
   * Notebooker
This isn't an exhaustive list of roles, and you can pretty much assign any role to any team member as long as it fits your team's goals and purposes. The roles listed above will exist in some shape or form in every team since every team needs people to perform these tasks.
Let's take a look at each of these roles and see what they do:
   * Captain - The captain manages team operations, ensuring everyone contributes to success. They carry significant responsibility, so choose an experienced, committed member.
   * Driver - Drives the robot, of course!
   * Analyst - Analyzing test data and matching observations is vital for team improvement. It guides what to maintain and change.
   * Programmer - Responsible for robot programming, making it functional and mobile.
   * Designer - Designing the robot is vital; CAD skills are beneficial. A well-designed robot is crucial for competition success.
   * Builder - Builders construct the robot based on the designer's plans.
   * Tester - Conducts experiments, crucial for testing new robot parts. Data collected guides improvements, analyzed by the analyst.
   * Notebooker - Creating an outstanding engineering notebook is critical, as it can lead to awards like the Design Award, a path to the World Championship in VEX Robotics.
How to delegate?
Generally, it will be the captain's job to delegate roles to teammates since it is the captain's job to manage team operations. Once again, make sure that your team's captain has the most time to devote to robotics since they will have the most commitment out of anybody else. Drivers should also be decided by a similar category to a captain in that they also need to have a lot of time to devote to the team and should ideally have a bit of prior controller experience. All the other roles should preferably be assigned based on team member preference to make sure teammates are happy with their roles. Otherwise, it will be up to the captain to decide which teammate will have the best performance in which role.




Optimal Team Size
The optimal team size is 4-5 members. This is the ideal size for team members who have time to commit to robotics. Anything more than 5 starts to result in problems; not every team member can contribute to the team.
But, this isn't a steadfast rule because there are times when smaller or larger teams can also work fine.
A team of 2-3 members can work if robotics is part of your free time and you are willing to spend numerous hours every single day in the week towards Robotics.
A team of 6+ can work if not all team members have enough time to commit to robotics, so more members allow the workload to be lighter on each teammate.
Regardless of the size of your team, you need to ask yourself the underlying question: can this team size fulfill the objectives of robotics that have been set aside?
If your answer is NO: then you probably need more members so you can complete whatever your objective is.
If your answer is YES: then you are good to go!
Time Management
Time, a clockwork conundrum!
Time is always moving and always limited. In Robotics, time management is a crucial part of success, since you always have less time than you think. Thus, it is important to allocate time effectively.
Firstly, it's important to create a plan so that your team knows what to expect and when to expect it. A good plan helps your team stay on task and lays out the foundations of what they will be doing for the foreseeable future.
One of the ways to establish a good plan is through making a timeline via a GANTT Chart.
A GANTT chart outlines the different phases of the design process and details how much time is devoted to each phase. For example, we allocated the first half of May for brainstorming and design, and the second half for prototyping.
  

Here is an example of a Gantt Chart which illustrates a team's timeline from when the competition is announced in May to when the first competition is in August
It is important to note that every team's GANTT Chart will be different since every team has their own unique goals that will likely vary from team to team.
Setting timely goals is the key to success.
Resource Management
Truly, your team and your time are your most important resources. But, in this section, we will go over resource management in a different sense--as it relates to physical resources like metal and motors.
Label your parts
Label all valuable electronic components, so they don't get lost, including:
   * Batteries
   * Battery chargers
   * Brains
   * Motors
Usually, if you lose a battery at a competition but have your team number on it, then some kind soul will return it to your team.
  

This label has saved our battery more than once!
Organize your parts
Of course! The benefits of organization are obvious; nobody wants to dig around in a box for a few minutes just to find the right screw. But seriously, organize your parts! There are many great, cheap plastic storage containers on Amazon. Many teams also use the Robosource box or heavy duty organizers with wheels.
​
Stuck?
That's okay, let's fix it
Along the journey of VEX robotics, it's easy to get stuck. Sometimes, your team is waiting on a part to come in, or can't figure out their design, or don't know how to build what they need. This is normal, but it's important to get out of these ruts as soon as possible, since they can stall progress for weeks or even months.
Ask yourself the most important question: what is holding your team back from moving on?
Based on your answer to the above question, here's some advice from our experience:
   * Design? Watch robot reveals, matches, tournaments online. See what strategies work, and which ones don't. Ask other teams why they made their robot the way they did, and learn from them. Don't try to design it all yourself--no robot is completely original.
   * Building? Again, watch robot reveals, pausing the video to see how teams built and supported their mechanisms. CAD helps a ton when building, so invest time into making one. Ask other teams for help, and don't be defensive when offered constructive criticism.
   * Coding? Keep it simple--the way all good code is. Take a look at our coding tutorials, and if those don't help, ask more experienced teams. Test things one step at a time, and find where the code went wrong.
   * Team dynamics? When team members disagree, it's nearly impossible to make progress. All disagreements come down to a difference in perspective--some people value good notebooks, some value original designs, some value what works in matches. Talk out your differences, find the root cause of the schism, and remember that you are all working towards the same ultimate goal. The best option is usually compromise between the two perspectives in question.
​
Physics
Physics works!
Physics is the study of the motion and nature of objects. Obviously, this plays a huge role in Robotics.
One of the primary concepts from physics is the idea of force. At a base level, a force is a push or pull that makes an object change direction.
   * The wheels of the robot apply a force on the ground, which pushes the robot forward
   * Rubber bands impart force on a catapult arm, causing it to slam upward
   * An intake exerts a force on a game object, making it move in a different direction
The two most important applications of force are torque and stress forces. Torque is simply rotational force, and stress forces are internal to the robot.
Torque
What is Torque?
Torque is a vector which means its has a magnitude and a direction. At its most basic level is a measure of the force that can cause an object to rotate about an axis. Just like force causes an object to accelerate in linear kinematics torque causes an object to accelerate in angular kinematics       
How do we calculate torque?
The formula to calculate the magnitude of torque is given as:
​
�=�∗����(�)
τ=F∗dsin(θ)
where:
   * τ is the torque
   * F is the force applied to the rotating object
   * d is the distance of the applied force from the point of rotation
   * θ is the angle of the applied vector force in relation to the rotating arm. This arm is also known as the moment arm
The concept of torque is essential in robotics as it is a fundamental of motors, gears, and levers which are used to transmit power and motion. To drive the robot you need to torque to accelerate, hold a top speed and to push other opponents. It is also needed to lift heavier objects faster and while keeping the speed of the robot.
Torque Calculator
If you can't figure out what θ should be, it's probably 90 degrees
Alternate Link: https://html-7159868.codehs.me/torque.html​
​
Gear Ratios
Gears are obviously a very important part of how a robot moves and its functions work, however when using gears calculations have to made to determine the gear ratio.
As shown in the example below, there is usually one gear driving and then the rest are driven by that gear. In this scenario like many there is one smaller gear and another larger one.
​
  

  

The gears in VEX are always made in proportion to the number of teeth. The ratio of the teeth in each gear is known as the gear ratio and this is determined based on the ratio of speed to torque that is needed. With gears the speed and torque are inversely related. As shown in the diagram, when the driving gear is larger (has more teeth) than the driven gear the speed is increased however the torque is decrease. The same is true vice versa. When the smaller gear is driving, the torque is increased and the speed is decreased.
This ratio is calculated using the following formula:
GEAR RATIO = (TEETH OF DRIVING GEAR) / (TEETH OF DRIVEN GEAR)
If the ratio is between 0 and 1, then the gear system has a torque advantage, but if the gear ratio is greater than 1, it has a speed advantage. Having a good balance between speed and torque is an important part of VEX Robotics.
​
​
Stress Forces
In robotics the concept of forces is essential to understand to limit the damage to your robot in competition. In VEX robotics there are 3 common stress forces: Bending, Torsion, Compression/Tension.
  

Bending is the most common of the stress forces and it comes when a force is applied perpendicular to the length of the object. This is most common in lifts
Torsion can be common in underdeveloped robots. Torsion happens when a piece of metal (usually a long piece) is twisted. This is most common when sparsely supported metals are involved in high torque situations 
Compression/Tension are opposing pushing(compression) or pulling(tension) forces that are often seen at connections between pieces through screws, standoffs, or spacers that become inconsistent over time.
When a metal is subject to stress, it it can deform either elastically (temporarily) or plastically (permanently). If the metal breaks it is known as yielding or failure.
Stress can also affect the properties of the metal like the ductility, malleability, and toughness. This means that if the metal undergoes stress it will be less able to withstand further stress.
Ways to combat this stress include applying appropriate protective coatings and designing structures to distribute stress evenly.
Extra stuff
96504 Gallery
Fun pictures...
  

String!
  

We don't talk about our Spin Up intake
  

We shot through their robot and won by 2 points
  

This is why we box
  

Forge your own path. Or, in this case, your own hole
  

27/28. If you know, you know
  

Sacrifices have to be made...
  

Clear!
  

Don't overthink it.
​
VEX Team Resources (Over Under)
We are here to help
Primary Resources
Game video: https://www.youtube.com/watch?v=dvDqEI7qO34​
Game Manual (READ THIS!):  https://www.vexrobotics.com/over-under-manual​
"How to Win Robotics" - a document giving an overview of the process of Robotics, made by a former club member: https://docs.google.com/document/d/1ss3dj3vwZIJbd0fW2elEkKdIoimpplIeJ7vIDK2Wzq0​
"101 Things I Wish I'd known..." - another overview of VEX robotics, with good general advice: https://www.vexforum.com/t/101-things-i-wish-id-known-before-my-first-vex-tournament/16081​
"VEX Notebooking Guide" - explains the Engineering Design Notebook well: https://docs.google.com/document/d/1_Q3tK04eIctlpk9GPR97G4Y_mjCfG2P7fL3U60Ilepc/edit?usp=sharing​
Over Under Robot Designs
Finals match from the first major VEX tournament (MOA). This is great for getting an idea of how this game is played at a high level by other teams: https://www.youtube.com/watch?v=sYvphItqic0​
#1 Skills run in the World (as of 9/5/23). Skills is how you qualify to States and Worlds! https://www.youtube.com/watch?v=HOCC7GQ2VHM​
Peruse this page if you please: https://www.youtube.com/results?search_query=vex+over+under​
________________


Please note that the rest of this website is a work in progress (as of 10/23/23) and will be updated throughout the semester.
Driving Simulator
Want to test out how it feels to drive your robot design before you build it? We made a driving simulator with fairly accurate physics, so you can get a feel for different drivetrains.


VEX V5 C++ API
Namespaces
	 
	this_thread
	 
	

Classes
	class  
	__tridevice
	 
	Use this class to get access to Three Wire Port functions and members. More...
	 
	class  
	accelerometer
	 
	Use this class when programming with an accelerometer sensor. More...
	 
	class  
	analog_in
	 
	Use this class when programming with an analog-in device. More...
	 
	class  
	bitmap
	 
	Bitmap image. More...
	 
	class  
	brain
	 
	Use the brain class to see battery information, SD card information, or write to the Screen. More...
	 
	class  
	bumper
	 
	Use this class when programming with the bumper device. More...
	 
	class  
	color
	 
	Use the color class to create Color objects. More...
	 
	class  
	competition
	 
	Use this class to set up your program for competitions. More...
	 
	class  
	controller
	 
	Use the controller class to get values from the remote controller as well as write to the controller's screen. More...
	 
	class  
	device
	 
	Use the device class to get information about a vex device plugged into the V5. More...
	 
	class  
	devices
	 
	Use the device class to get information about all of the vex devices plugged into the V5. More...
	 
	class  
	digital_in
	 
	Use this class when programming with a digital-in device. More...
	 
	class  
	digital_out
	 
	Use this class when programming with a digital-out device. More...
	 
	class  
	distance
	 
	Use the distance class to control the distance sensor. More...
	 
	class  
	drivetrain
	 
	class  
	encoder
	 
	Use this class when programming with an encoder. More...
	 
	class  
	guido
	 
	class  
	gyro
	 
	Use this class when programming with a gyro sensor. More...
	 
	class  
	inertial
	 
	Use the inertial class to control the inertial sensor. More...
	 
	class  
	led
	 
	Use this class when programming with a led device. More...
	 
	class  
	light
	 
	Use this class when programming with a light sensor. More...
	 
	class  
	limit
	 
	Use this class when programming with the limit switch. More...
	 
	class  
	line
	 
	Use this class when programming with a line follower. More...
	 
	class  
	motor
	 
	Use the motor class to control motor devices. More...
	 
	class  
	motor29
	 
	Use this class when programming a motor connected to a motor controller 29. More...
	 
	class  
	motor_group
	 
	class  
	motor_victor
	 
	Use this class when programming with a motor connected to a victor motor controller. More...
	 
	class  
	mutex
	 
	Use this class to create and control mutexes. More...
	 
	class  
	optical
	 
	Use the optical class to control the optical sensor. More...
	 
	class  
	pneumatics
	 
	Use this class when programming with a pneumatics device. More...
	 
	class  
	pot
	 
	Use this class when programming with a potentiometer. More...
	 
	class  
	pwm_out
	 
	Use this class when programming with a pwm-out device. More...
	 
	class  
	rotation
	 
	Use the rotation class to control absolute encoder devices. More...
	 
	class  
	safearray
	 
	class  
	servo
	 
	Use this class when programming with a servo device. More...
	 
	class  
	smartdrive
	 
	class  
	sonar
	 
	Use this class when programming with a sonar sensor. More...
	 
	class  
	thread
	 
	Use this class to create and control threads. More...
	 
	class  
	timer
	 
	Use the timer class to create timers for your program. More...
	 
	class  
	triport
	 
	Use this class to get and set information about devices on 3-wire ports. More...
	 
	class  
	vision
	 
	Use this class when programming the vision sensor. More...
	 
	

Enumerations
	enum  
	turnType { turnType::left = 0, turnType::right = 1, turnType::undefined = 0xFF }
	 
	enum  
	percentUnits { percentUnits::pct = 0 }
	 
	The measurement units for percentage values. More...
	 
	enum  
	timeUnits { timeUnits::sec, timeUnits::msec }
	 
	The measurement units for time values. More...
	 
	enum  
	currentUnits { currentUnits::amp }
	 
	The measurement units for current values. More...
	 
	enum  
	voltageUnits { voltageUnits::volt, voltageUnits::mV }
	 
	The measurement units for voltage values. More...
	 
	enum  
	powerUnits { powerUnits::watt }
	 
	The measurement units for power values. More...
	 
	enum  
	torqueUnits { torqueUnits::Nm, torqueUnits::InLb }
	 
	The measurement units for torque values. More...
	 
	enum  
	rotationUnits { rotationUnits::deg, rotationUnits::rev, rotationUnits::raw = 99 }
	 
	The measurement units for rotation values. More...
	 
	enum  
	velocityUnits { velocityUnits::pct = (int)percentUnits::pct, velocityUnits::rpm, velocityUnits::dps }
	 
	The measurement units for velocity values. More...
	 
	enum  
	distanceUnits { distanceUnits::mm, distanceUnits::in, distanceUnits::cm }
	 
	The measurement units for distance values. More...
	 
	enum  
	analogUnits {
  analogUnits::pct = (int)percentUnits::pct, analogUnits::range8bit, analogUnits::range10bit, analogUnits::range12bit,
  analogUnits::mV
}
	 
	The measurement units for analog values. More...
	 
	enum  
	temperatureUnits { temperatureUnits::celsius, temperatureUnits::fahrenheit, temperatureUnits::pct = 0xFF }
	 
	The measurement units for temperature values. More...
	 
	enum  
	directionType { directionType::fwd = 0, directionType::rev, directionType::undefined }
	 
	The defined units for direction values. More...
	 
	enum  
	brakeType { brakeType::coast = kV5MotorBrakeModeCoast, brakeType::brake = kV5MotorBrakeModeBrake, brakeType::hold = kV5MotorBrakeModeHold, brakeType::undefined }
	 
	The defined units for brake values. More...
	 
	enum  
	gearSetting { gearSetting::ratio36_1 = kMotorGearSet_36, gearSetting::ratio18_1 = kMotorGearSet_18, gearSetting::ratio6_1 = kMotorGearSet_06 }
	 
	The defined units for gear values. More...
	 
	enum  
	fontType {
  fontType::mono20 = 0, fontType::mono30, fontType::mono40, fontType::mono60,
  fontType::prop20, fontType::prop30, fontType::prop40, fontType::prop60,
  fontType::mono15, fontType::mono12, fontType::chinese16 = 0xf0
}
	 
	The defined units for font values. More...
	 
	enum  
	triportType {
  triportType::analogInput, triportType::analogOutput, triportType::digitalInput, triportType::digitalOutput,
  triportType::button, triportType::potentiometer, triportType::lineSensor, triportType::lightSensor,
  triportType::gyro, triportType::accelerometer, triportType::motor, triportType::servo,
  triportType::quadEncoder, triportType::sonar, triportType::motorS
}
	 
	The defined units for triport devices. More...
	 
	enum  
	controllerType { controllerType::primary = kControllerMaster, controllerType::partner = kControllerPartner }
	 
	The defined units for controller devices. More...
	 
	enum  
	axisType { axisType::xaxis, axisType::yaxis, axisType::zaxis }
	 
	The defined units for inertial sensor axis. More...
	 
	enum  
	orientationType { orientationType::roll, orientationType::pitch, orientationType::yaw }
	 
	The defined units for inertial sensor orientation. More...
	 
	enum  
	sizeType { sizeType::none, sizeType::small, sizeType::medium, sizeType::large }
	 
	The defined units for distance sensor object size. More...
	 
	enum  
	ledState { ledState::off, ledState::on }
	 
	The defined units for optical sensor led state. More...
	 
	

Functions
	void 
	wait (double time, timeUnits units=timeUnits::sec)
	 
	Wait for a specific amount of time. Identical to sleep() More...
	 
	void 
	sleep (double duration, timeUnits units=timeUnits::sec)
	 
	Wait for a specific amount of time. Identical to wait() More...
	 
	void 
	sleepMs (uint32_t duration)
	 
	Wait for a specific amount of time (in milliseconds) More...
	 
	double 
	clock ()
	 
	System time, in seconds. More...
	 
	uint32_t 
	clockMs ()
	 
	System time, in milliseconds. More...
	 
	uint64_t 
	clockUs ()
	 
	System time, in microseconds. More...
	 
	

Variables
	const rotationUnits 
	degrees
	 
	const rotationUnits 
	turns
	 
	const percentUnits 
	percent
	 
	const timeUnits 
	seconds
	 
	const distanceUnits 
	inches
	 
	const distanceUnits 
	mm
	 
	const directionType 
	forward
	 
	const directionType 
	reverse
	 
	const turnType 
	left
	 
	const turnType 
	right
	 
	const axisType 
	xaxis
	 
	const axisType 
	yaxis
	 
	const axisType 
	zaxis
	 
	const orientationType 
	roll
	 
	const orientationType 
	pitch
	 
	const orientationType 
	yaw
	 
	const fontType 
	monoM
	 
	const fontType 
	monoL
	 
	const fontType 
	monoXL
	 
	const fontType 
	monoXXL
	 
	const fontType 
	monoS
	 
	const fontType 
	monoXS
	 
	const fontType 
	propM
	 
	const fontType 
	propL
	 
	const fontType 
	propXL
	 
	const fontType 
	propXXL
	 
	const controllerType 
	primary
	 
	const controllerType 
	partner
	 
	const char * 
	rumbleLong
	 
	const char * 
	rumbleShort
	 
	const char * 
	rumblePulse
	 
	const int32_t 
	PORT1
	 
	const int32_t 
	PORT2
	 
	const int32_t 
	PORT3
	 
	const int32_t 
	PORT4
	 
	const int32_t 
	PORT5
	 
	const int32_t 
	PORT6
	 
	const int32_t 
	PORT7
	 
	const int32_t 
	PORT8
	 
	const int32_t 
	PORT9
	 
	const int32_t 
	PORT10
	 
	const int32_t 
	PORT11
	 
	const int32_t 
	PORT12
	 
	const int32_t 
	PORT13
	 
	const int32_t 
	PORT14
	 
	const int32_t 
	PORT15
	 
	const int32_t 
	PORT16
	 
	const int32_t 
	PORT17
	 
	const int32_t 
	PORT18
	 
	const int32_t 
	PORT19
	 
	const int32_t 
	PORT20
	 
	const int32_t 
	PORT21
	 
	const int32_t 
	PORT22
	 
	const percentUnits 
	pct
	 
	const timeUnits 
	sec
	 
	const timeUnits 
	msec
	 
	const voltageUnits 
	volt
	 
	const currentUnits 
	amp
	 
	const powerUnits 
	watt
	 
	const torqueUnits 
	Nm
	 
	const torqueUnits 
	InLb
	 
	const rotationUnits 
	deg
	 
	const rotationUnits 
	rev
	 
	const velocityUnits 
	rpm
	 
	const velocityUnits 
	dps
	 
	const temperatureUnits 
	celsius
	 
	const temperatureUnits 
	fahrenheit
	 
	const directionType 
	fwd
	 
	const brakeType 
	coast
	 
	const brakeType 
	brake
	 
	const brakeType 
	hold
	 
	const gearSetting 
	ratio36_1
	 
	const gearSetting 
	ratio18_1
	 
	const gearSetting 
	ratio6_1
	 
	const color & 
	black
	 
	const color & 
	white
	 
	const color & 
	red
	 
	const color & 
	green
	 
	const color & 
	blue
	 
	const color & 
	yellow
	 
	const color & 
	orange
	 
	const color & 
	purple
	 
	const color & 
	cyan
	 
	const color & 
	transparent
	 
	const fontType 
	mono20
	 
	const fontType 
	mono30
	 
	const fontType 
	mono40
	 
	const fontType 
	mono60
	 
	const fontType 
	mono15
	 
	const fontType 
	mono12
	 
	const fontType 
	prop20
	 
	const fontType 
	prop30
	 
	const fontType 
	prop40
	 
	const fontType 
	prop60
	 
	const analogUnits 
	range8bit
	 
	const analogUnits 
	range10bit
	 
	const analogUnits 
	range12bit
	 
	const analogUnits 
	mV
	 
	Detailed Description
device class
Vision sensor device class.
Triport device class.
All devices class.
base interface class used with IMU and gyro
a safe array template
Enumeration Type Documentation
◆ turnType


enum vex::turnType
	

	strong
	

Enumerator
	left 
	

	right 
	

	undefined 
	

	◆ percentUnits


enum vex::percentUnits
	

	strong
	The measurement units for percentage values.
Enumerator
	pct 
	A percentage unit that represents a value from 0% to 100%.
	◆ timeUnits


enum vex::timeUnits
	

	strong
	The measurement units for time values.
Enumerator
	sec 
	A time unit that is measured in seconds.
	msec 
	A time unit that is measured in milliseconds.
	◆ currentUnits


enum vex::currentUnits
	

	strong
	The measurement units for current values.
Enumerator
	amp 
	A current unit that is measured in amps.
	◆ voltageUnits


enum vex::voltageUnits
	

	strong
	The measurement units for voltage values.
Enumerator
	volt 
	A voltage unit that is measured in volts.
	mV 
	The measurement units for power values millivolts.
	◆ powerUnits


enum vex::powerUnits
	

	strong
	The measurement units for power values.
Enumerator
	watt 
	A power unit that is measured in watts.
	◆ torqueUnits


enum vex::torqueUnits
	

	strong
	The measurement units for torque values.
Enumerator
	Nm 
	A torque unit that is measured in Newton Meters.
	InLb 
	A torque unit that is measured in Inch Pounds.
	◆ rotationUnits


enum vex::rotationUnits
	

	strong
	The measurement units for rotation values.
Enumerator
	deg 
	A rotation unit that is measured in degrees.
	rev 
	A rotation unit that is measured in revolutions.
	raw 
	A rotation unit that is measured in raw data form.
	◆ velocityUnits


enum vex::velocityUnits
	

	strong
	The measurement units for velocity values.
Enumerator
	pct 
	A velocity unit that is measured in percentage.
	rpm 
	A velocity unit that is measured in rotations per minute.
	dps 
	A velocity unit that is measured in degrees per second.
	◆ distanceUnits


enum vex::distanceUnits
	

	strong
	The measurement units for distance values.
Enumerator
	mm 
	A distance unit that is measured in millimeters.
	in 
	A distance unit that is measured in inches.
	cm 
	A distance unit that is measured in centimeters.
	◆ analogUnits


enum vex::analogUnits
	

	strong
	The measurement units for analog values.
Enumerator
	pct 
	An analog unit that is measured in percentage.
	range8bit 
	An analog unit that is measured in an 8-bit analog value (a value with 256 possible states).
	range10bit 
	An analog unit that is measured in a 10-bit analog value (a value with 1024 possible states).
	range12bit 
	An analog unit that is measured in a 12-bit analog value (a value with 4096 possible states).
	mV 
	An analog unit that is measured in millivolts.
	◆ temperatureUnits


enum vex::temperatureUnits
	

	strong
	The measurement units for temperature values.
Enumerator
	celsius 
	A temperature unit that is measured in degrees Celsius.
	fahrenheit 
	A temperature unit that is measured in degrees Fahrenheit.
	pct 
	A temperature unit that is measured in percentage of allowed range.
	◆ directionType


enum vex::directionType
	

	strong
	The defined units for direction values.
Enumerator
	fwd 
	A direction unit that is defined as forward.
	rev 
	A direction unit that is defined as backward.
	undefined 
	

	◆ brakeType


enum vex::brakeType
	

	strong
	The defined units for brake values.
Enumerator
	coast 
	A brake unit that is defined as coast.
	brake 
	A brake unit that is defined as brake.
	hold 
	A brake unit that is defined as hold.
	undefined 
	

	◆ gearSetting


enum vex::gearSetting
	

	strong
	The defined units for gear values.
Enumerator
	ratio36_1 
	A gear unit that is defined as the red 36:1 gear cartridge used in V5 Smart Motors.
	ratio18_1 
	A gear unit that is defined as the green 18:1 gear cartridge used in V5 Smart Motors.
	ratio6_1 
	A gear unit that is defined as the blue 6:1 gear cartridge used in V5 Smart Motors.
	◆ fontType


enum vex::fontType
	

	strong
	The defined units for font values.
Enumerator
	mono20 
	A font unit that is defined as mono20.
	mono30 
	A font unit that is defined as mono30.
	mono40 
	A font unit that is defined as mono40.
	mono60 
	A font unit that is defined as mono60.
	prop20 
	A font unit that is defined as prop20.
	prop30 
	A font unit that is defined as prop30.
	prop40 
	A font unit that is defined as prop40.
	prop60 
	A font unit that is defined as prop60.
	mono15 
	A font unit that is defined as mono15.
	mono12 
	A font unit that is defined as mono12.
	chinese16 
	A font supporting Chinese characters.
	◆ triportType


enum vex::triportType
	

	strong
	The defined units for triport devices.
Enumerator
	analogInput 
	A triport unit that is defined as an analog input.
	analogOutput 
	A triport unit that is defined as an analog output.
	digitalInput 
	A triport unit that is defined as a digital input.
	digitalOutput 
	A triport unit that is defined as a digital output.
	button 
	A triport unit that is defined as a button.
	potentiometer 
	A triport unit that is defined as a potentiometer.
	lineSensor 
	A triport unit that is defined as a line sensor.
	lightSensor 
	A triport unit that is defined as a light sensor.
	gyro 
	A triport unit that is defined as a gyro.
	accelerometer 
	A triport unit that is defined as an accelerometer.
	motor 
	A triport unit that is defined as a motor.
	servo 
	A triport unit that is defined as a servo.
	quadEncoder 
	A triport unit that is defined as a quadrature encoder.
	sonar 
	A triport unit that is defined as a sonar.
	motorS 
	A triport unit that is defined as a motor with slew rate control.
	◆ controllerType


enum vex::controllerType
	

	strong
	The defined units for controller devices.
Enumerator
	primary 
	A controller unit defined as a primary controller.
	partner 
	A controller unit defined as a partner controller.
	◆ axisType


enum vex::axisType
	

	strong
	The defined units for inertial sensor axis.
Enumerator
	xaxis 
	

	yaxis 
	

	zaxis 
	

	◆ orientationType


enum vex::orientationType
	

	strong
	The defined units for inertial sensor orientation.
Enumerator
	roll 
	

	pitch 
	

	yaw 
	

	◆ sizeType


enum vex::sizeType
	

	strong
	The defined units for distance sensor object size.
Enumerator
	none 
	

	small 
	

	medium 
	

	large 
	

	◆ ledState


enum vex::ledState
	

	strong
	The defined units for optical sensor led state.
Enumerator
	off 
	

	on 
	

	Function Documentation
◆ wait()
void vex::wait
	(
	double 
	time,
	

	

	timeUnits 
	units = timeUnits::sec 
	

	)
	

	

	Wait for a specific amount of time. Identical to sleep()
Parameters
time
	The length of time to wait
	units
	The units of time (default seconds)
	◆ sleep()
void vex::sleep
	(
	double 
	duration,
	

	

	timeUnits 
	units = timeUnits::sec 
	

	)
	

	

	Wait for a specific amount of time. Identical to wait()
Parameters
duration
	The length of time to wait
	units
	The units of time (default seconds)
	◆ sleepMs()
void vex::sleepMs
	(
	uint32_t 
	duration
	)
	

	Wait for a specific amount of time (in milliseconds)
Parameters
duration
	The length of time to wait (in milliseconds)
	◆ clock()
double vex::clock
	(
	

	)
	

	System time, in seconds.
◆ clockMs()
uint32_t vex::clockMs
	(
	

	)
	

	System time, in milliseconds.
◆ clockUs()
uint64_t vex::clockUs
	(
	

	)
	

	System time, in microseconds.
Variable Documentation
◆ degrees
const rotationUnits vex::degrees
	◆ turns
const rotationUnits vex::turns
	◆ percent
const percentUnits vex::percent
	◆ seconds
const timeUnits vex::seconds
	◆ inches
const distanceUnits vex::inches
	◆ mm
const distanceUnits vex::mm
	◆ forward
const directionType vex::forward
	◆ reverse
const directionType vex::reverse
	◆ left
const turnType vex::left
	◆ right
const turnType vex::right
	◆ xaxis
const axisType vex::xaxis
	◆ yaxis
const axisType vex::yaxis
	◆ zaxis
const axisType vex::zaxis
	◆ roll
const orientationType vex::roll
	◆ pitch
const orientationType vex::pitch
	◆ yaw
const orientationType vex::yaw
	◆ monoM
const fontType vex::monoM
	◆ monoL
const fontType vex::monoL
	◆ monoXL
const fontType vex::monoXL
	◆ monoXXL
const fontType vex::monoXXL
	◆ monoS
const fontType vex::monoS
	◆ monoXS
const fontType vex::monoXS
	◆ propM
const fontType vex::propM
	◆ propL
const fontType vex::propL
	◆ propXL
const fontType vex::propXL
	◆ propXXL
const fontType vex::propXXL
	◆ primary
const controllerType vex::primary
	◆ partner
const controllerType vex::partner
	◆ rumbleLong
const char* vex::rumbleLong
	◆ rumbleShort
const char* vex::rumbleShort
	◆ rumblePulse
const char* vex::rumblePulse
	◆ PORT1
const int32_t vex::PORT1
	◆ PORT2
const int32_t vex::PORT2
	◆ PORT3
const int32_t vex::PORT3
	◆ PORT4
const int32_t vex::PORT4
	◆ PORT5
const int32_t vex::PORT5
	◆ PORT6
const int32_t vex::PORT6
	◆ PORT7
const int32_t vex::PORT7
	◆ PORT8
const int32_t vex::PORT8
	◆ PORT9
const int32_t vex::PORT9
	◆ PORT10
const int32_t vex::PORT10
	◆ PORT11
const int32_t vex::PORT11
	◆ PORT12
const int32_t vex::PORT12
	◆ PORT13
const int32_t vex::PORT13
	◆ PORT14
const int32_t vex::PORT14
	◆ PORT15
const int32_t vex::PORT15
	◆ PORT16
const int32_t vex::PORT16
	◆ PORT17
const int32_t vex::PORT17
	◆ PORT18
const int32_t vex::PORT18
	◆ PORT19
const int32_t vex::PORT19
	◆ PORT20
const int32_t vex::PORT20
	◆ PORT21
const int32_t vex::PORT21
	◆ PORT22
const int32_t vex::PORT22
	◆ pct
const percentUnits vex::pct
	◆ sec
const timeUnits vex::sec
	◆ msec
const timeUnits vex::msec
	◆ volt
const voltageUnits vex::volt
	◆ amp
const currentUnits vex::amp
	◆ watt
const powerUnits vex::watt
	◆ Nm
const torqueUnits vex::Nm
	◆ InLb
const torqueUnits vex::InLb
	◆ deg
const rotationUnits vex::deg
	◆ rev
const rotationUnits vex::rev
	◆ rpm
const velocityUnits vex::rpm
	◆ dps
const velocityUnits vex::dps
	◆ celsius
const temperatureUnits vex::celsius
	◆ fahrenheit
const temperatureUnits vex::fahrenheit
	◆ fwd
const directionType vex::fwd
	◆ coast
const brakeType vex::coast
	◆ brake
const brakeType vex::brake
	◆ hold
const brakeType vex::hold
	◆ ratio36_1
const gearSetting vex::ratio36_1
	◆ ratio18_1
const gearSetting vex::ratio18_1
	◆ ratio6_1
const gearSetting vex::ratio6_1
	◆ black
const color& vex::black
	◆ white
const color& vex::white
	◆ red
const color& vex::red
	◆ green
const color& vex::green
	◆ blue
const color& vex::blue
	◆ yellow
const color& vex::yellow
	◆ orange
const color& vex::orange
	◆ purple
const color& vex::purple
	◆ cyan
const color& vex::cyan
	◆ transparent
const color& vex::transparent
	◆ mono20
const fontType vex::mono20
	◆ mono30
const fontType vex::mono30
	◆ mono40
const fontType vex::mono40
	◆ mono60
const fontType vex::mono60
	◆ mono15
const fontType vex::mono15
	◆ mono12
const fontType vex::mono12
	◆ prop20
const fontType vex::prop20
	◆ prop30
const fontType vex::prop30
	◆ prop40
const fontType vex::prop40
	◆ prop60
const fontType vex::prop60
	◆ range8bit
const analogUnits vex::range8bit
	◆ range10bit
const analogUnits vex::range10bit
	◆ range12bit
const analogUnits vex::range12bit
	◆ mV
const analogUnits vex::mV
	________________






Functions
	int32_t 
	get_id ()
	 
	Gets the ID of the thread. More...
	 
	void 
	yield ()
	 
	Suspends the current thread. More...
	 
	void 
	sleep_for (uint32_t time_ms)
	 
	sleep_for More...
	 
	void 
	sleep_until (uint32_t time)
	 
	sleep_until More...
	 
	void 
	setPriority (int32_t priority)
	 
	Sets the priority of the current thread. More...
	 
	int32_t 
	priority ()
	 
	Gets the priority of the current thread. More...
	 
	Function Documentation
◆ get_id()
int32_t vex::this_thread::get_id
	(
	

	)
	

	Gets the ID of the thread.
Returns
Returns an integer that represents the thread's ID.
◆ yield()
void vex::this_thread::yield
	(
	

	)
	

	Suspends the current thread.
◆ sleep_for()
void vex::this_thread::sleep_for
	(
	uint32_t 
	time_ms
	)
	

	sleep_for
Suspends the current thread until the time is expired in milliseconds.
Parameters
time_ms
	The amount of time for the thread to sleep.
	◆ sleep_until()
void vex::this_thread::sleep_until
	(
	uint32_t 
	time
	)
	

	sleep_until
Sleeps until the system timer reaches the time specified in the parameter.
Parameters
time
	The amount of time for the thread to sleep.
	◆ setPriority()
void vex::this_thread::setPriority
	(
	int32_t 
	priority
	)
	

	Sets the priority of the current thread.
Parameters
priority
	The priority of the thread to be set to.
	◆ priority()
int32_t vex::this_thread::priority
	(
	

	)
	

	Gets the priority of the current thread.
Returns
Returns the priority of the current thread as an integer.
________________






Full Spin Up Code
/*----------------------------------------------------------------------------*/
/* */
/* Module: main.cpp */
/* Author: VEX */
/* Created: Thu Sep 26 2019 */
/* Description: Competition Template */
/* */
/*----------------------------------------------------------------------------*/
// ---- START VEXCODE CONFIGURED DEVICES ----
// Robot Configuration:
// [Name] [Type] [Port(s)]
// Controller1 controller
// Flywheel motor_group 1, 2
// LeftMotors motor_group 3, 4
// RightMotors motor_group 5, 6
// RightEncoder encoder A, B
// LeftEncoder encoder C, D
// BackEncoder encoder E, F
// Intake motor 7
// Indexer motor 8
// Wings digital_out G
// Optical optical 9
// VisionSensor vision 10
// Inertial1 inertial 19
// Inertial2 inertial 20
// LineTracker line H
// Motor motor 11
// ---- END VEXCODE CONFIGURED DEVICES ----
//neccessary stuff
#include "vex.h"
#include <iostream>
#include <cmath>
#include <vector>
#include <cstdlib>
using namespace vex;
competition Competition;
//global variables
int flywheelLastPos = 0; //the last position of the flywheel in degrees, based on the internal motor encoders
int flywheelTargetRPM = 1800; //the target RPM of the flywheel
bool flywheelOn = false; //true or false, whether or not the flywheel is on right now
bool auton = false; //whether or not the robot is being controlled autonomously
float driveSpeed = 1.0f; //driving (forward and backward) speed of the robot
float turnSpeed = .7f; //turning speed of the robot
int drawMode = 0; //what to draw on the brain screen? 0: flywheel 1: PID 2: vision sensor 3: status update 4: odom
int tempDrawMode = 0; //store the previous draw mode temporarily
bool useTBH = true;//controls how the flywheel speed is updated
int overHeatingTimer = 0; //keeps track of how often to display an overheating warning
bool firstCross = false; //whether or not the first cross of the target RPM line has occured yet
int autonType = 1; //the type of autonomous to use
float driveDistance = 0; //drive distnace for drive PID
bool opticalMode = false;//whether or not the optical sensor dictates when discs are shot.
double gain = 0.000143; //was 0.00013 before, the gain variable for TBH velocity control
double defaultGain = 0.000143; //the default gain, was .000143
bool visionAlign = false; //whether or not to align to the goal using the vision sensor
bool visionTrackRed = true; //whether or not to track red objects as the goal
bool visionTrackBlue = true; //whether or not to track blue objects as the goal
float speedPID = 1; // the speed to run the motors at in PID loops, range is0-1
bool tripleShooting = false; //whether or not a triple shot is active
float motorPowerApprox = 0.61; //default guess for the motor power, for 1800 rpm, for the flywheel
//odometry constants
float pos[2] = {0, 0}; //x and y global position of the robot
float angle = 0; //the angle of the robot relative to the starting angle, in radians
float sideWheelRadius = 4.8258328 * 3633.0 / 3600; //in inches, the distance between each side wheel and the tracking center, 4.8125
//above, it was 4.8623 for the first half of the second week of summer camp
float backWheelRadius = 1; //in inches, the distance between the back wheel and the tracking center
int prevLeftEncoder = 0;//the previous reading of the left encoder, in degrees
int prevRightEncoder = 0;//the previous reading of the right encoder, in degrees
int prevBackEncoder = 0; //the previous reading of the back encoder, in degrees
//helper functions
void printController(float i) {
//prints a number to the controller console (very handy for debugging)
Controller1.Screen.clearLine(3);
Controller1.Screen.setCursor(3, 1);
Controller1.Screen.print(i);
}
void printControllerSetup() {
//sets up the controller to be printed on
Controller1.Screen.clearLine(3);
Controller1.Screen.setCursor(3, 1);
}
//graphing data, used for flywheel velocity control
void graphFlywheelVelocity(std::vector<int> velocityHistory, std::vector<int> powerHistory) {
//Given some data, display a graph showing the current velocity and voltage draw of the flywheel motor
//the velocity history is a list of integers (range: 0-the maximum flywheel speed) that is the current speed of the flywheel, in RPM
//the power history is a list of integers (range: 0-100) that is the percentage amount representing how much power the motors applied.
//For example, if the motor was spun at half power at a certain point in time, this corresponding value would be 50
//setup: clear screen and draw the target line
Brain.Screen.clearScreen();
Brain.Screen.setPenWidth(2);
Brain.Screen.setPenColor(white);
Brain.Screen.drawLine(0, 60, 480, 60);
Brain.Screen.setPenWidth(1);
Brain.Screen.setPenColor(green);
//also display some helpful information on the top of the brain screen
Brain.Screen.setCursor(1, 1);
Brain.Screen.clearLine(1);
Brain.Screen.print(Flywheel.current());
Brain.Screen.print(" Amperes ");
Brain.Screen.print(Flywheel.velocity(rpm) * 5); //times 5 to account for the gear ratio of the flywheel
Brain.Screen.print(" RPM ");
Brain.Screen.print(Flywheel.voltage());
Brain.Screen.print(" Volts ");
//establish parameters that determine where the graph is drawn on the screen
//for y, bottom (0) is 215 and top (100) is 60
int minY = 60;
int maxY = 230;
//for x, start at 10 and end at 470, so don't draw the graph within 10px of the border
int minX = 10;
int maxX = 470;
//horizontalScale adjusts how much of the graph to draw on the screen (ex: last 3 seconds or last 10 seconds)
float horizontalScale = 400;
//loop through every data point and draw a line between it and the next one, to create a smooth graph.
for (int i = std::max((int)velocityHistory.size() - (int)horizontalScale, 0); i < velocityHistory.size() - 1; i++) {
//calculate where to draw this part of the graph
int x = maxX - (maxX - minX) * (velocityHistory.size() - i) / horizontalScale;
//graph velocity
Brain.Screen.setPenColor(green);
Brain.Screen.drawLine(x, maxY - (float)velocityHistory.at(i) / flywheelTargetRPM * (maxY - minY), x + (float)(maxX - minX) / horizontalScale, maxY - (float)velocityHistory.at(i + 1) / flywheelTargetRPM * (maxY - minY));
//graph power
Brain.Screen.setPenColor(orange);
Brain.Screen.drawLine(x, maxY - powerHistory.at(i) / 100.0f * (maxY - minY), x + (float)(maxX - minX) / horizontalScale, maxY - powerHistory.at(i + 1) / 100.0f * (maxY - minY));
}
}
//graphing data, used for PID tuning
void graphPID(std::vector<int> errorHistory, std::vector<float> powerHistory, int goal, float error, int time) {
//goal is the PID goal
//error history is a list of all of the errors
//powerHistory is -1 to 1 of the power applied
//setup: clear screen and draw the target line
Brain.Screen.clearScreen();
Brain.Screen.setPenWidth(2);
Brain.Screen.setPenColor(white);
Brain.Screen.drawLine(0, 60, 480, 60);
Brain.Screen.setPenWidth(1);
Brain.Screen.setPenColor(green);
//also display amps
Brain.Screen.setCursor(1, 1);
Brain.Screen.clearLine(1);
Brain.Screen.print(" Final Error: ");
Brain.Screen.print(error);
Brain.Screen.print(" Time: ");
Brain.Screen.print(time);
//y positions
//bottom (0) is 215
//top (100) is 60
//above (110) (overshoot) is <60
int minY = 60;
int maxY = 230;
//for x, start at 30 and end at 450
int minX = 10;
int maxX = 470;
for (int i = 0; i < errorHistory.size() - 1; i++) {
int x = minX + (maxX - minX) * i / errorHistory.size();
//graph velocity
Brain.Screen.setPenColor(green);
Brain.Screen.drawLine(x, minY + (float)errorHistory.at(i) / goal * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), minY + (float)errorHistory.at(i + 1) / goal * (maxY - minY));
//graph power
//change color based on direction
if (powerHistory.at(i) > 0) {
Brain.Screen.setPenColor(orange);
} else {
Brain.Screen.setPenColor(yellow);
}
Brain.Screen.drawLine(x, maxY - std::abs(powerHistory.at(i)) * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), maxY - std::abs(powerHistory.at(i + 1)) * (maxY - minY));
}
}
void drawRobotPath(std::vector<int> x, std::vector<int> y) {
//draws the path of the robot (as discerned from odometry) on the brain of the robot
Brain.Screen.clearScreen();
Brain.Screen.setPenWidth(1);
Brain.Screen.setPenColor(green);
Brain.Screen.drawLine(0, 120, 480, 120);
Brain.Screen.drawLine(240, 0, 240, 240);
Brain.Screen.setPenColor(white);
Brain.Screen.setPenWidth(2);
int originX = 240;
int originY = 120;
float scale = 2;
for (int i = 0; i < x.size() - 1; i++) {
Brain.Screen.drawLine(x.at(i) * scale + originX, 240 - (y.at(i) * scale + originY), x.at(i + 1) * scale + originX, 240 - (y.at(i + 1) * scale + originY));
}
//draw robot as dot
Brain.Screen.setPenColor(red);
Brain.Screen.drawCircle(x.at(x.size() - 1) * scale + originX, 240 - (y.at(x.size() - 1) * scale + originY), 5);
}
/*template for a thread/task (task is a higher level abstraction of thread):
int myTaskCallback() {
while (true) {
//do something
wait(25, msec);
}
// A task's callback must return an int, even though the code will never get
// here. You must return an int here. Tasks can exit, but this one does not.
return 0;
}
in some other function like main():
task myTask = task(myTaskCallback);
*/
int updatePosition() {
//keep track of position over time
std::vector<int> x;
std::vector<int> y;
while (true) {
//odometry, yay!
//caclulate the robot's absolute position
//first calculate the change since last time
float changeLeft = LeftEncoder.position(degrees) - prevLeftEncoder;
float changeRight = RightEncoder.position(degrees) - prevRightEncoder;
float changeBack = BackEncoder.position(degrees) - prevBackEncoder;
prevLeftEncoder = LeftEncoder.position(degrees);
prevRightEncoder = RightEncoder.position(degrees);
prevBackEncoder = BackEncoder.position(degrees);
//convert the changes to inches
//degrees * (1 revolution / 360 degrees) * (pi * 2.75" (diameter of wheel) / 1 revolution) = inches
//although the actual wheel size differs by a small amount, it was 2.73 for the first half of the second week of summer camp
//after that it is off by 1.021836:1 difference (back wheel)
//for the right wheel our new ratio is 1.011
float distLeft = (float)changeLeft / 360 * M_PI * 2.75;
float distRight = (float)changeRight / 360 * M_PI * 2.75;
float distBack = (float)changeBack / 360 * M_PI * 2.75;
//calculates the change in angle according to an equation derived in the notebook
float changeInAngle = (distLeft- distRight) / (sideWheelRadius * 2);
float newAngle = angle + changeInAngle;
//now calculate the change in translational offset
//x is forward, so a changeX of +2.5 means the robot moved directly forward 2.5 inches
//y is sideways, left is positive. Think of a cartesian coordinate system.
float changeX = 0; //we need a third tracking wheel for this
float changeY = 0; //set to zero initially
//we avoid a divide by zero error by splitting the code based on whether the change in angle is zero or not
if (changeInAngle == 0) {
changeY = distBack; //there was no turning, so the lateral change in position is interepereted simply
changeX = distRight;
} else {
//now you have to account for the fact that going forward while turning changes the position differently
changeX = 2 * sin(changeInAngle / 2) * ((distRight / changeInAngle) + sideWheelRadius);
changeY = 2 * sin(changeInAngle / 2) * ((distBack / changeInAngle) + backWheelRadius);
}
//now convert local position change to global position
//the local coordinate system is offset from the global one by (angle + newAngle) / 2
//first convert to polar coordinates
float radius = sqrt(changeY * changeY + changeX * changeX);
float globalAngle = atan2(changeY, changeX) + (angle + newAngle) / 2;
//now convert back to local coordinates
float changeGlobalX = cos(globalAngle) * radius;
float changeGlobalY = sin(globalAngle) * radius;
//update global position
pos[0] += changeGlobalX;
pos[1] += changeGlobalY;
angle += changeInAngle;
//graph the robot's position if necessary
if (drawMode == 3) {
x.push_back(pos[0]);
y.push_back(pos[1]);
drawRobotPath(x, y);
}
wait(4, msec);
}
return 0;
}
int flywheelVelocityControl(){
int prevError = 0; //previous error
float motorPower = 0; //between 0 and 1, the proportion of motor power applied (.7 = 70% power
float prevMotorPower = 0; //previous motor power, used to limit the slew rate
float powerAtZero = 0; //the tbh variable, the best guess of the flywheel power to use
std::vector<int> velocityHistory; //keep track of velocity over time
std::vector<int> powerHistory; //keep track of motor power over time
//this task keeps track of the velocity of the flywheel and manages the motor power input
while (true) {
//first, get the current velocity of the flywheel. 5:1 gear ratio
int speed = Flywheel.velocity(rpm) * 5;
int error = flywheelTargetRPM - speed;
//now for the tbh (take back half) algorithm
//similar to PID but minimizes overshoot
motorPower = motorPower + (gain * error);
///keep motor power variable in proper range
if (motorPower > 1) motorPower = 1;
if (motorPower < 0) motorPower = 0;
//control the slew rate (dampen voltage differences), basically don't jerk the motor too much
float slewRate = 0.05f;
if (motorPower > prevMotorPower + slewRate) {
motorPower = prevMotorPower + slewRate;
}
if (motorPower < prevMotorPower - slewRate) {
motorPower = prevMotorPower - slewRate;
}
//the other key component of the take back half algorithm, the part that takes back half
if (error >= 0 != prevError >= 0) {
//the graph crossed the target RPM line
if (!firstCross) {
//the first time you cross the target RPM, slow it down to the voltage estimate to make it stabilize faster
firstCross = true;
motorPower = motorPowerApprox;
} else {
//every time after the first time you cross the target RPM, set the voltage to be the average of what it currently is and what is was at the previous cross
motorPower = 0.5 * (motorPower + powerAtZero);
}
powerAtZero = motorPower;
}
//if the flyhweel is off, take that into account
if (!flywheelOn) {
motorPower = 0;
powerAtZero = 0;
firstCross = false;
}
if (tripleShooting) motorPower = .75;//might have to undo this, helps with consistency in some situations.
//now apply motor power, if we are using this control method
if (useTBH) Flywheel.spin(forward, 12 * motorPower, volt);
//update history of velocity and motor power
velocityHistory.push_back(speed);
powerHistory.push_back(motorPower * 100);
//graph if necessary
if (drawMode == 0) {
graphFlywheelVelocity(velocityHistory, powerHistory);
}
//update previous variables
prevMotorPower = motorPower;
prevError = error;
//don't hog CPU
wait(20, msec);
}
return 0;
}
void driveCode() {
//drives the robot around based on controller input, double arcade controls
//don't drive if the robot is currently being controlled autonomously
if (auton) return;
LeftMotors.spin(forward);
RightMotors.spin(forward);
int forward1 = Controller1.Axis3.value();
int turn = Controller1.Axis1.value();
printController(LeftMotors.velocity(rpm));
//fix drift, or not
//if (std::abs(forward) < 7) forward = 0;
//if (std::abs(turn) < 7) turn = 0;
//calculate proper motor powers
int left = forward1 * driveSpeed + turn * turnSpeed;
int right = forward1 * driveSpeed - turn * turnSpeed;
//set velocity of drive motors
LeftMotors.setVelocity(left, percent);
RightMotors.setVelocity(right, percent);
LeftMotors.spin(forward, left, percent);
}
//now all of the functions for autonomous / odometry
int turnToPoint(float x, float y) {
//given an X and Y position on the field, turn to that point using PID
//PID constants:
float kP = 0.03;
float kI = 0.03;
float kD = 0.001;
//other variables:
float error = 0;
float motorPower = 0;
float integral = 0;
float derivative = 0;
float prevError = 0;
float prevMotorPower = 0;
//first, calculate the angle we need to be at
float deltaX = x - pos[0];
float deltaY = y - pos[1];
float finalAngle = atan2(deltaY, deltaX); //in radians
//also clamp the current angle to [0, 2pi)
while (angle >= 2 * M_PI) {
angle -= 2 * M_PI;
}
while (angle < 0) {
angle += 2 * M_PI;
}
while(true) {
//calculate error / integral / derivative, of error vs time graph
error = finalAngle - angle;
integral += error;
derivative = error - prevError;
//core of the PID loop here, calculate the necessary motor power
motorPower = kP * error + kI * integral + kD * derivative;
///keep motor power variable in proper range, 0-1
if (motorPower > 1) motorPower = 1;
if (motorPower < 0) motorPower = 0;
//control the slew rate (dampen voltage differences), limits harsh acceleration
float slewRate = 0.05f;
if (motorPower > prevMotorPower + slewRate) {
motorPower = prevMotorPower + slewRate;
}
if (motorPower < prevMotorPower - slewRate) {
motorPower = prevMotorPower - slewRate;
}
//apply motor voltages
LeftMotors.spin(forward, 12 * motorPower, volt);
RightMotors.spin(reverse, 12 * motorPower, volt);
//update final variables
prevMotorPower = motorPower;
prevError = error;
//don't hog CPU
wait(20, msec);
}
return 0;
}
int drivePID() {
//drive straightforward with driveDistance as the distance, in degrees (for now)
//forward PID constants:
float kP1 = 0.0048;//.003 and 0 for other two
float kI1 = 0.00003;
float kD1 = 0.013;
//turning PID constants:
float kP2 = 0.001;
float kI2 = 0.00;
float kD2 = 0.00;
//other variables for forward PID
float error1 = 0;
float integral1 = 0;
float derivative1 = 0;
float prevError1 = 0;
//other variables for turn PID
float error2 = 0;
float integral2 = 0;
float derivative2 = 0;
float prevError2 = 0;
//motor power variables
float motorPower = 0;
float prevMotorPower = 0;
//lists
std::vector<int> errorHistory; //keep track of error over time
std::vector<float> powerHistory; //keep track of motor power over time
int time = 0;
float currentDist = 0; //the distance the robot is from its starting point
RightMotors.setPosition(0, degrees);
LeftMotors.setPosition(0, degrees);
while(true) {
currentDist = (RightMotors.position(degrees) + LeftMotors.position(degrees)) / 2;
//calculate error / integral / derivative, of error vs time graph
error1 = driveDistance - currentDist;
if (std::abs(error1) < 200) {
//weigh the integral double when error < 50
if (std::abs(error1) < 50) {
integral1 += error1 * 2;
} else {
integral1 += error1;
}
}
derivative1 = error1 - prevError1;
error2 = RightMotors.position(degrees) - RightMotors.position(degrees);
integral2 += error2;
derivative2 = error2 - prevError2;
//core of the PID loop here, calculate the necessary motor power, combine both PID loops
motorPower = (kP1 * error1 + kI1 * integral1 + kD1 * derivative1);
///keep motor power variable in proper range, -1 to 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
//control the slew rate (dampen voltage differences), limits harsh acceleration
float slewRate = 0.08f;
if (motorPower > prevMotorPower + slewRate) {
motorPower = prevMotorPower + slewRate;
}
if (motorPower < prevMotorPower - slewRate) {
motorPower = prevMotorPower - slewRate;
}
//apply motor voltages
LeftMotors.spin(forward, 11 * motorPower * speedPID, volt);
RightMotors.spin(forward, 11 * motorPower * speedPID, volt);
//update final variables
prevMotorPower = motorPower;
prevError1 = error1;
prevError2 = error2;
//update histories
errorHistory.push_back(error1);
powerHistory.push_back(std::abs(motorPower));
time += 20;
//break out of the loop if we have reached the target or B is pressed
//we have reached the target if the error is less than 5 and the previous error is similar
if (Controller1.ButtonB.pressing() || ((std::abs(error1) < 5) && std::abs(error1 - prevError1) < 2)) {
break;
}
//don't hog CPU
wait(20, msec);
}
wait(20, msec); //allow time for status update to draw itself
//graph the PID at the end
drawMode = 1;
graphPID(errorHistory, powerHistory, driveDistance, error1, time);
LeftMotors.stop();
RightMotors.stop();
return 0;
}
int turnPID() {
//drive straightforward with driveDistance as the distance, in degrees (for now)
//forward PID constants:
//zieger-nicholas on 11/14: ku = .07 period = .5 sec
float kP1 = 0.034;//.0245;//.0225 and 0 for other two
float kI1 = 0.0037;//0.0017; //0.0017
float kD1 = 0.19;//0.06;//0.010;
//not bad; 0.017, 0.0042, 0
//not bad v2; .04, 0.0037, 0.23
//other variables for forward PID
float error = 0;
float integral = 0;
float derivative = 0;
float prevError = 0;
//motor power variables
float motorPower = 0;
float prevMotorPower = 0;
//lists
std::vector<int> errorHistory; //keep track of error over time
std::vector<float> powerHistory; //keep track of motor power over time
int time = 0;
float currentDist = 0; //the distance the robot is from its starting point, rotationally
float startDist = (Inertial1.rotation(degrees) + Inertial2.rotation(degrees)) / 2;
//Inertial1.setHeading(0, degrees);
//Inertial2.setHeading(0, degrees);
//float degOffset
while(true) {
//float deg1 = Inertial1.heading(degrees);
currentDist = (Inertial1.rotation(degrees) + Inertial2.rotation(degrees)) / -2 + startDist;
//printController(Inertial1.rotation(degrees));
//calculate error / integral / derivative, of error vs time graph
error = driveDistance - currentDist;
if (std::abs(error) < 8) {
//weigh the integral double when error < 4
if (std::abs(error) < 3) {
integral += error * 2;
} else {
integral += error;
}
} else {
integral = 0;
}
derivative = error - prevError;
//core of the PID loop here, calculate the necessary motor power, combine both PID loops
motorPower = (kP1 * error + kI1 * integral + kD1 * derivative);
///keep motor power variable in proper range, -1 to 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
//control the slew rate (dampen voltage differences), limits harsh acceleration
float slewRate = 0.08f;
if (motorPower > prevMotorPower + slewRate) {
motorPower = prevMotorPower + slewRate;
}
if (motorPower < prevMotorPower - slewRate) {
motorPower = prevMotorPower - slewRate;
}
//minimum voltage of 11V * .2
/*if (std::abs(slewRate) != .12) {
if (std::abs(motorPower) < 0.2) {
if (motorPower > 0) {
motorPower = 0.2;
} else {
motorPower = -0.2;
}
}
}*/
//apply motor voltages
LeftMotors.spin(forward, 11 * motorPower * -1, volt);
RightMotors.spin(forward, 11 * motorPower, volt);
//update histories
errorHistory.push_back(error);
powerHistory.push_back(motorPower);
time += 20;
//update final variables
//printController(error);
//break out of the loop if we have reached the target or B is pressed
//we have reached the target if the error is less than 5 and the previous error is similar
if (Controller1.ButtonB.pressing() || ((std::abs(error) < 0.5) && std::abs(error - prevError) < 0.3)) {
break;
}
prevMotorPower = motorPower;
prevError = error;
//don't hog CPU
wait(20, msec);
}
wait(20, msec); //allow time for status update to draw itself
//graph the PID at the end
drawMode = 1;
graphPID(errorHistory, powerHistory, driveDistance, error, time);
LeftMotors.stop();
RightMotors.stop();
return 0;
}
void aDrive(float distance) {
driveDistance = distance;
drivePID();
}
void aTurn(float distance) {
driveDistance = distance;
turnPID();
}
void aDriveFor(int speed, int time) {
//drive the robot forward (or backward if speed is negative) for a specified amount of milliseconds
RightMotors.spin(forward);
LeftMotors.spin(forward);
RightMotors.setVelocity(speed, percent);
LeftMotors.setVelocity(speed, percent);
wait(time, msec);
LeftMotors.stop();
RightMotors.stop();
}
void fireIndexer() {
Indexer.spin(forward, 12, volt);
wait(130, msec);
Indexer.spin(forward, 6, volt);
wait(60, msec);
Indexer.spin(reverse, 6, volt);
wait(100, msec);
Indexer.stop();
}
//below code copied from jpearman on vexforum
int screen_origin_x = 150;
int screen_origin_y = 20;
int screen_width = 316;
int screen_height = 212;
// function to draw a single object
void drawObject( vision::object &obj, vex::color c ) {
int labelOffset = 0;
Brain.Screen.setPenColor( vex::color::yellow );
Brain.Screen.drawRectangle( screen_origin_x + obj.originX, screen_origin_y + obj.originY, obj.width, obj.height, c );
Brain.Screen.setFont( vex::fontType::mono12 );
if( obj.originX > 280 )
labelOffset = -40;
if( obj.originY > 10 )
Brain.Screen.printAt( screen_origin_x + obj.originX + labelOffset, screen_origin_y + obj.originY-3, "Sig %o", obj.id );
else
Brain.Screen.printAt( screen_origin_x + obj.originX + labelOffset, screen_origin_y + obj.originY+10, "Sig %o", obj.id );
}
// function to draw all objects found
void drawObjects( vision &v, vex::color c, bool clearScreen ) {
if( clearScreen ) {
Brain.Screen.setPenColor( vex::color::black );
Brain.Screen.drawRectangle( screen_origin_x, screen_origin_y, screen_width, screen_height, vex::color::black );
}
for(int i=0;i<v.objectCount;i++)
drawObject( v.objects[i], c );
}
int alignToGoal() {
//aligns the robot to the goal using the vision sensor
float finalValue;
//first of all, find the goal using the vision sensor
do {
int x = 0;
int center = 158; // the goal should be at x=158 when lined up perfectly with the robot
int maxArea = 0; //we will align to the signature with the highest area on the screen (generally the right one)
int maxX = -1;
for (int k = 0; k < 5; k++) {
if (visionTrackRed) {
VisionSensor.takeSnapshot( VisionSensor__RED_GOAL );
//if this is the new highest area, then update the variable
int area = VisionSensor.largestObject.width * VisionSensor.largestObject.height;
if (area > maxArea && area > 400) {
maxArea = area;
maxX = VisionSensor.largestObject.originX + (VisionSensor.largestObject.width / 2);
}
}
if (visionTrackBlue) {
VisionSensor.takeSnapshot( VisionSensor__BLUE_GOAL );
int area = VisionSensor.largestObject.width * VisionSensor.largestObject.height;
if (area > maxArea && area > 400) {
maxArea = area;
maxX = VisionSensor.largestObject.originX + (VisionSensor.largestObject.width / 2);
}
}
wait(20, msec);
}
if (maxX == -1) {
//dont do anything if no goal is detected
x = center;
printControllerSetup();
Controller1.Screen.print("No goal found");
} else {
x = maxX;
}
float value = x / 316.0 * 60; //angle, in degrees, that we are at. 30 degrees is dead center
finalValue = (value - 30) * -7.55; //degree-to-PID units conversion
//only turn if we are off by a good bit (over 1 degree)
if (std::abs(finalValue) > 7) {
aTurn(finalValue);
}
} while (std::abs(finalValue) > 7);
return 0;
}
void flipRoller() {
//flips a roller, just like that
Intake.spin(forward, 11, volt);
while(Optical.hue() > 50 || !Optical.isNearObject()) {
RightMotors.spin(forward, 2, volt);
LeftMotors.spin(forward, 2, volt);
wait(20, msec);
}
Intake.stop();
}
void autonomousProgram(void) {
auton = true;
//wait until inertial is calibrated
while (Inertial1.isCalibrating()) {
wait(30, msec);
printControllerSetup();
Controller1.Screen.print("Calibrating Inertial");
}
int timerValue = Brain.Timer.value();
//run the autonomous program based on the autonType variable
if (autonType == 0) {
//testing one
aTurn(flywheelTargetRPM);
} else if (autonType == 1) {
//standard autonomous, left side roller + shoot 5 discs
flywheelOn = true;
flywheelTargetRPM = 2200; //45
motorPowerApprox = 0.73;
gain = 0.000123;
Intake.spin(forward, 11, volt);
aDriveFor(20, 300);
Intake.stop();
aDrive(-100);
//aTurn(-2); //;UNDO
drawMode = 0;
wait(1700, msec); ///UNDOO
fireIndexer();
wait(1100, msec);
fireIndexer();
wait(300, msec);
aDrive(-100);
motorPowerApprox = 0.61;
flywheelTargetRPM = 2160;
gain = 0.000093;
aTurn(119);
Intake.spin(reverse, 12, volt);
aDrive(750);
speedPID = 1;
aDrive(300);
aDrive(300);
speedPID = 1;
//aDriveFor(50, 2100);
//wait(200, msec);
aTurn(-89);
drawMode = 0;
//Intake.spin(forward, 12, volt);
wait(100, msec);
fireIndexer();
Intake.spin(reverse, 12, volt);
wait(350, msec);
fireIndexer();
tripleShooting = true;
wait(400, msec);
Intake.stop();
fireIndexer();
wait(400, msec);
tripleShooting = false;
flywheelOn = false;
flywheelTargetRPM = 1800;
gain = defaultGain;
} else if (autonType == 2) {
flywheelOn = true;
flywheelTargetRPM = 2120;
Intake.spin(reverse, 11, volt);
aDrive(700);
aTurn(150);
Intake.stop();
drawMode = 0;
wait(800, msec);
fireIndexer();
wait(200, msec);
fireIndexer();
wait(100, msec);
fireIndexer();
wait(200, msec);
flywheelTargetRPM = 2060;
aTurn(-96);
Intake.spin(reverse, 11, volt);
speedPID = .8;
aDrive(850);
speedPID = 1;
wait(100, msec);
//Intake.spin(forward, 6, volt);
aTurn(78);
Intake.spin(reverse, 11, volt);
fireIndexer();
wait(300, msec);
Intake.stop();
fireIndexer();
wait(200, msec);
aTurn(103);
aDrive(1600);
RightMotors.spin(forward);
LeftMotors.spin(forward);
RightMotors.setVelocity(20, percent);
LeftMotors.setVelocity(100, percent);
wait(600, msec);
RightMotors.stop();
LeftMotors.stop();
Intake.spin(forward, 11, volt);
wait(100, msec);
aDriveFor(20, 400);
Intake.stop();
aDriveFor(-90, 100);
/*aTurn(-160);
drawMode = 0;
wait(1700, msec);
fireIndexer();
wait(200, msec);
fireIndexer();
aDrive(-100);
aTurn(-460);
flywheelTargetRPM = 2100;
aDrive(-620);
aTurn(650);
Intake.spin(forward, 11, volt);
aDriveFor(20, 800);
Intake.stop();
aDrive(-130);
aTurn(-930);
Intake.spin(reverse, 11, volt);
speedPID = 0.6;
aDrive(1800);
speedPID = 1;
//Intake.spin(forward, 5, volt);
aTurn(610);
wait(200, msec);
Intake.spin(reverse, 11, volt);
fireIndexer();
wait(400, msec);
Intake.stop();*/
flywheelOn = false;
flywheelTargetRPM = 1800;
} else if (autonType == 3) {
//go from roller to match load station
aDrive(-400);
aTurn(-300);
aDrive(-700);
aTurn(160);
LeftMotors.spin(forward);
RightMotors.spin(forward);
for (int i = 0; i < 25; i++) {
int forward = -50;
int turn = (25 - (i * 1.0)) * -1;
//calculate proper motor powers
int left = forward * driveSpeed + turn * turnSpeed;
int right = forward * driveSpeed - turn * turnSpeed;
//set velocity of drive motors
LeftMotors.setVelocity(left, percent);
RightMotors.setVelocity(right, percent);
wait(40, msec);
}
} else if (autonType == 4) {
alignToGoal();
} else if (autonType == 5) {
//programming skills
flywheelOn = true;
wait(2000, msec);
opticalMode = true;
flywheelTargetRPM = 1800;
Intake.spin(forward);
Intake.setVelocity(100, percent);
wait(12000, msec);
Intake.stop();
opticalMode = false;
//flywheelOn = false;
aTurn(-92);
aDrive(550);
aTurn(90);
Intake.spin(reverse);
aDrive(300);
wait(500, msec);
aDrive(200);
wait(500, msec);
aDrive(200);
aDrive(-800);
aTurn(-25);
Intake.stop();
fireIndexer();
wait(600, msec);
fireIndexer();
wait(600, msec);
fireIndexer();
wait(300, msec);
aTurn(26);
Intake.spin(reverse);
aDrive(1000);
wait(500, msec);
aDrive(200);
wait(500, msec);
aDrive(200);
wait(500, msec);
aDrive(200);
aTurn(-90);
aDrive(600);
aTurn(-90);
Intake.stop();
aDriveFor(-50, 1800);
aDrive(400);
aTurn(-90);
aDrive(-500);
fireIndexer();
wait(600, msec);
fireIndexer();
wait(600, msec);
fireIndexer();
wait(300, msec);
aDrive(1500);
aTurn(-45);
Wings.set(true);
wait(2000, msec);
aDrive(-100);
//aDrive(300);
/*
aTurn(45);
aDrive(300);
Wings.set(true);
wait(2000, msec);
aDrive(-100);*/
flywheelOn = false;
flywheelTargetRPM = 1800;
} else if (autonType == 6) {
flywheelOn = true;
flywheelTargetRPM = 2100;
gain = 0.000093;
wait(3000, msec);
drawMode = 0;
Intake.spin(forward, 12, volt);
wait(100, msec);
fireIndexer();
Intake.spin(reverse, 12, volt);
wait(350, msec);
fireIndexer();
tripleShooting = true;
wait(400, msec);
Intake.stop();
fireIndexer();
wait(400, msec);
//the above code is very precise
tripleShooting = false;
flywheelOn = false;
} else if (autonType == 7) {
//flip a roller
flipRoller();
Intake.stop();
//flywheelOn = false;
}
printController(Brain.Timer.value() - timerValue);//print time it took
auton = false;
}
int opticalModeLoop() {
//shoot discs if the optical sensor detects something
while (true) {
//check if it is optical sensor mode
wait(25, msec);
if (!opticalMode) continue;
//printControllerSetup();
//Controller1.Screen.print(Optical.isNearObject());
//disc detected when reflectivity is greater than 90
if (LineTracker.reflectivity() > 90) {
wait(300, msec);
//fire one disc
Indexer.spin(forward, 12, volt);
wait(130, msec);
Indexer.spin(forward, 6, volt);
wait(60, msec);
Indexer.spin(reverse, 6, volt);
wait(70, msec);
Indexer.stop();
wait(100, msec);
}
}
return 0;
}
void buttonL1Pressed() {
if (Controller1.ButtonB.pressing()){
visionTrackRed = true;
visionTrackBlue = false;
printControllerSetup();
Controller1.Screen.print("Vision Track: RED");
} else {
Intake.spin(forward, 11, volt);
}
}
void buttonL2Pressed() {
if (Controller1.ButtonB.pressing()){
visionTrackRed = false;
visionTrackBlue = true;
printControllerSetup();
Controller1.Screen.print("Vision Track: BLUE");
} else {
Intake.spin(reverse, 11, volt);
}
}
void buttonL1Released() {
Intake.stop();
}
void buttonL2Released() {
Intake.stop();
}
void buttonR1Pressed() {
//retract extension mechanism
Wings.set(false);
}
void buttonR2Pressed() {
//expand extension mechanism, if button B is pressed
if (Controller1.ButtonB.pressing()) {
Wings.set(true);
}
}
void buttonUpPressed() {
//increase the RPM of the flywheel when the up button is pressed
if (Controller1.ButtonB.pressing()) {
//fine control if another button is held down
flywheelTargetRPM += 10;
} else {
flywheelTargetRPM += 100;
}
printController(flywheelTargetRPM);
}
void buttonDownPressed() {
//decrease the RPM of the flywheel when the down button is pressed
if (Controller1.ButtonB.pressing()) {
//fine control if another button is held down
flywheelTargetRPM -= 10;
} else {
flywheelTargetRPM -= 100;
}
printController(flywheelTargetRPM);
}
void buttonLeftPressed() {
//align to goal first lol
auton = true;
if (visionAlign) {
alignToGoal();
} else {
//display the number
int x = 0;
int center = 158;// the goal should be at x=100 when lined up perfectly with the robot
//look at the leftmost instance of the goal
int maxArea = 0;
int maxX = -1;
for (int k = 0; k < 5; k++) {
if (visionTrackRed) {
VisionSensor.takeSnapshot( VisionSensor__RED_GOAL );
//if this is the new highest area, then update the variable
int area = VisionSensor.largestObject.width * VisionSensor.largestObject.height;
if (area > maxArea && area > 400) {
maxArea = area;
maxX = VisionSensor.largestObject.originX + (VisionSensor.largestObject.width / 2);
}
}
if (visionTrackBlue) {
VisionSensor.takeSnapshot( VisionSensor__BLUE_GOAL );
int area = VisionSensor.largestObject.width * VisionSensor.largestObject.height;
if (area > maxArea && area > 400) {
maxArea = area;
maxX = VisionSensor.largestObject.originX + (VisionSensor.largestObject.width / 2);
}
}
wait(20, msec);
}
if (maxX == -1) {
//dont do anything if no goal is detected
x = center;
} else {
x = maxX;
}
printController((x / 316.0 * 60) - 30);
}
auton = false;
//automatically fire all three disc
Indexer.spin(forward, 11, volt);
wait(200, msec);
Indexer.spin(reverse, 11, volt);
wait(120, msec);
Indexer.spin(reverse, 3, volt);
tripleShooting = true;
wait(50, msec);
Indexer.spin(forward, 11, volt);
wait(200, msec);
Indexer.spin(reverse, 11, volt);
wait(120, msec);
Indexer.spin(reverse, 3, volt);
wait(50, msec);
Indexer.spin(forward, 11, volt);
wait(200, msec);
Indexer.spin(reverse, 11, volt);
wait(120, msec);
Indexer.stop();
tripleShooting = false;
}
void buttonRightPressed() {
//if b is pressed, toggle optical sensor mode
if (Controller1.ButtonB.pressing()) {
opticalMode = !opticalMode;
//display a note on the controller, and also spin the intake in the right way
if (opticalMode) {
Intake.spin(forward);
Intake.setVelocity(100, percent);
printControllerSetup();
Controller1.Screen.print("Autoshoot mode enabled");
//gain = 0.000103;
flywheelTargetRPM = 1800;
} else {
Intake.stop();
printControllerSetup();
Controller1.Screen.print("Autoshoot mode disabled");
gain = defaultGain; //was 0.00013 before
flywheelTargetRPM = 1800;
}
} else {
//fire one disc
fireIndexer();
}
}
void buttonXPressed() {
//turn on or off the flywheel
//count the time it takes for rpm to reach 0
/*
if (!flywheelOn) {
int fTimer = 0;
while (Flywheel.velocity(rpm) != 0){
wait(20, msec);
fTimer += 20;
}
printController(fTimer);
}*/
if (Controller1.ButtonB.pressing()) {
//change the drawing mode and let the driver know
if (tempDrawMode < 9) {
drawMode = tempDrawMode + 1;
} else {
drawMode = tempDrawMode - 9;
}
if (drawMode > 3) drawMode = 0;
tempDrawMode = drawMode + 10;//let the release Button B function know that we changed the drawing mode
//printController(drawMode);
printControllerSetup();
if (drawMode == 0) {
Controller1.Screen.print("Draw: Flywheel graph");
} else if (drawMode == 1) {
Controller1.Screen.print("Draw: PID graph");
} else if (drawMode == 2) {
Controller1.Screen.print("Draw: Vision sensor");
}
} else {
flywheelOn = !flywheelOn;
//backup: velocity control based on internal motor PID's (it's bad)
if (useTBH == false) {
if (flywheelOn) {
Flywheel.setVelocity(100, percent);
Flywheel.spin(forward);
} else {
Flywheel.setVelocity(0, percent);
}
}
}
}
void buttonXReleased() {
}
void buttonAPressed() {
//reset odometry; if B is held down then display odometry constants instead
if (!Controller1.ButtonB.pressing()) {
/*
Controller1.Screen.clearScreen();
Controller1.Screen.setCursor(1, 1);
Controller1.Screen.print(pos[0]);
Controller1.Screen.newLine();
Controller1.Screen.print(pos[1]);
Controller1.Screen.newLine();
Controller1.Screen.print(angle * 180 / M_PI);
*/
} else {
pos[0] = 0;
pos[1] = 0;
angle = 0;
}
}
void buttonBPressed() {
//prints out a bunch of useful information on the brain screen--a status check
Brain.Screen.clearScreen();
Brain.Screen.setCursor(1, 1);
Brain.Screen.print("Battery voltage: ");
Brain.Screen.print(Brain.Battery.voltage());
Brain.Screen.newLine();
Brain.Screen.print("Battery current: ");
Brain.Screen.print(Brain.Battery.current());
Brain.Screen.newLine();
Brain.Screen.print("Left Motors temp: ");
Brain.Screen.print(LeftMotors.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Right motors temp: ");
Brain.Screen.print(RightMotors.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Flywheel temp: ");
Brain.Screen.print(Flywheel.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Intake temp: ");
Brain.Screen.print(Intake.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Indexer temp: ");
Brain.Screen.print(Indexer.temperature(percent));
Brain.Screen.newLine();
tempDrawMode = drawMode;
drawMode = 3;
}
void buttonBReleased() {
//we changed the drawing mode while we were holding down B, so change it to the new one
if (tempDrawMode < 9) {
drawMode = tempDrawMode;
}
}
void buttonYPressed() {
//change up what is drawn on the brain screen.
//drawPath = !drawPath;
//drawFlywheelGraph = !drawFlywheelGraph;
//start autonomous if A is held down while pressing Y
if (Controller1.ButtonA.pressing()) {
autonomousProgram();
} else if (Controller1.ButtonB.pressing()) {
visionAlign = !visionAlign;
printControllerSetup();
if (visionAlign) {
Controller1.Screen.print("Vision align enabled");
} else {
Controller1.Screen.print("Vision align disabled");
}
} else {
autonType++;
if (autonType > 7) autonType = 0;
printControllerSetup();
Controller1.Screen.print("Auton type: ");
Controller1.Screen.print(autonType);
}
}
void checkOverheating() {
//check for overheating in any of the motors
if (LeftMotors.temperature(percent) > 50 || RightMotors.temperature(percent) > 50 || Flywheel.temperature(percent) > 50 || Intake.temperature(percent) > 50 || Indexer.temperature(percent) > 50) {
if (overHeatingTimer == 0) {
Controller1.rumble(rumbleLong);
printControllerSetup();
Controller1.Screen.print("Overheating Warning");
overHeatingTimer++;
} else {
overHeatingTimer++;
if (overHeatingTimer > 750) overHeatingTimer = 0;
}
}
if (Controller1.ButtonR2.pressing() && !Controller1.ButtonB.pressing()) {
printController(Intake.velocity(rpm));
wait(500, msec);
}
}
void init() {
//initialize settings, variables, and callback functions
Flywheel.setStopping(coast);
Intake.setStopping(coast);
Indexer.setStopping(coast);
LeftMotors.setStopping(coast);
RightMotors.setStopping(coast);
gain = defaultGain;
//callbacks for other driver controls
//intake
Controller1.ButtonL1.pressed(buttonL1Pressed);
Controller1.ButtonL2.pressed(buttonL2Pressed);
Controller1.ButtonL1.released(buttonL1Released);
Controller1.ButtonL2.released(buttonL2Released);
//expansion
Controller1.ButtonR1.pressed(buttonR1Pressed);
Controller1.ButtonR2.pressed(buttonR2Pressed);
//velocity control
Controller1.ButtonUp.pressed(buttonUpPressed);
Controller1.ButtonDown.pressed(buttonDownPressed);
//indexer
Controller1.ButtonLeft.pressed(buttonLeftPressed);
Controller1.ButtonRight.pressed(buttonRightPressed);
//other functions
Controller1.ButtonX.pressed(buttonXPressed);
Controller1.ButtonX.released(buttonXReleased);
Controller1.ButtonA.pressed(buttonAPressed);
Controller1.ButtonB.pressed(buttonBPressed);
Controller1.ButtonB.released(buttonBReleased);
Controller1.ButtonY.pressed(buttonYPressed);
//background tasks (very important)
//task myTask = task(updatePosition);
task myTask1 = task(flywheelVelocityControl);
task myTask2 = task(opticalModeLoop);
}
void pre_auton(void) {
init();
Inertial1.calibrate();
Inertial2.calibrate();
}
void usercontrol(void) {
auton = false;
flywheelTargetRPM = 1800;
gain = defaultGain;
tripleShooting = false;
while (1) {
driveCode();
//testing with encoders
/*
Controller1.Screen.clearScreen();
Controller1.Screen.setCursor(1, 1);
Controller1.Screen.print(RightEncoder.position(degrees));
Controller1.Screen.newLine();
Controller1.Screen.print(LeftEncoder.position(degrees));
Controller1.Screen.newLine();
Controller1.Screen.print(BackEncoder.position(degrees));
*/
//copied from jpearman
// Draw an area representing the vision sensor field of view
if (drawMode == 2) {
Brain.Screen.clearScreen( vex::color::black );
Brain.Screen.setPenColor( vex::color::green );
Brain.Screen.drawRectangle( screen_origin_x-1, screen_origin_y-1, screen_width+2, screen_height+2 );
// request any objects with signature 1
int numberObjects = VisionSensor.takeSnapshot(VisionSensor__RED_GOAL);
Brain.Screen.setPenColor( vex::color::white );
Brain.Screen.setFont( mono20 );
Brain.Screen.setCursor( 2, 2 );
Brain.Screen.print( "Sig 1 %2d", (int)numberObjects );
// draw any objects found
drawObjects( VisionSensor, vex::color::red, true );
numberObjects = VisionSensor.takeSnapshot(VisionSensor__BLUE_GOAL);
// draw any objects found
drawObjects( VisionSensor, vex::color::blue, false );
wait(180, msec);
}
wait(20, msec);
}
}
int main() {
// Initializing Robot Configuration. DO NOT REMOVE!
vexcodeInit();
// Set up callbacks for autonomous and driver control periods.
Competition.autonomous(autonomousProgram);
Competition.drivercontrol(usercontrol);
// Run the pre-autonomous function, basically initialize
pre_auton();
// Prevent main from exiting with an infinite loop.
while (true) {
checkOverheating();
//printController(Optical.hue());
wait(20, msec);
}
}


Full Over Under Code
//necessary stuff
#include "vex.h"
#include <iostream>
#include <cmath>
#include <vector>
#include <cstdlib>
using namespace vex;
competition Competition;
//global variables
bool auton = false; //whether or not the robot is being controlled autonomously
float driveSpeed = 1.0f; //driving (forward and backward) speed of the robot
float turnSpeed = .6f; //turning speed of the robot
int drawMode = 3; //what to draw on the brain screen? 0: flywheel 1: PID 2: vision sensor 3: status update 4: odom
int tempDrawMode = 0; //store the previous draw mode temporarily
int overHeatingTimer = 0; //keeps track of how often to display an overheating warning
int autonType = 2; //the type of autonomous to use
float driveDistance = 0; //drive distance for drive PID
float speedPID = 1; // the speed to run the motors at in PID loops, range is 0-1
bool kickerOn = false; //true or false, whether or not the kicker is on right now
bool intakeOn = false; //true or false, whether or not the kicker is on right now
bool wingsActive = false; //true or false, whether or not the wings are active
bool elevationActive = false; //true or false, whether or not the elevation mechanism is active
bool scraperActive = false; //true or false, whether or not the scraper is active
bool exitPID = false; //true or false, whether or not to exit a PID loop
bool curveDrive = true; //true or false, whether or not the curve drive is active
task autonTask; //stores the autonomous task
//helper functions
void printController(float i) {
//prints a number to the controller console (very handy for debugging)
Controller1.Screen.clearLine(3);
Controller1.Screen.setCursor(3, 1);
Controller1.Screen.print(i);
}
void printControllerSetup() {
//sets up the controller to be printed on
Controller1.Screen.clearLine(3);
Controller1.Screen.setCursor(3, 1);
}
//graphing data, used for PID tuning
void graphPID(std::vector<int> errorHistory, std::vector<float> powerHistory, int goal, float error, int time) {
//goal is the PID goal
//error history is a list of all of the errors
//powerHistory is -1 to 1 of the power applied
//setup: clear screen and draw the target line
Brain.Screen.clearScreen();
Brain.Screen.setPenWidth(2);
Brain.Screen.setPenColor(white);
Brain.Screen.drawLine(0, 60, 480, 60);
Brain.Screen.setPenWidth(1);
Brain.Screen.setPenColor(green);
//also display amps
Brain.Screen.setCursor(1, 1);
Brain.Screen.clearLine(1);
Brain.Screen.print(" Final Error: ");
Brain.Screen.print(error);
Brain.Screen.print(" Time: ");
Brain.Screen.print(time);
//y positions
//bottom (0) is 215
//top (100) is 60
//above (110) (overshoot) is <60
int minY = 60;
int maxY = 230;
//for x, start at 30 and end at 450
int minX = 10;
int maxX = 470;
for (int i = 0; i < errorHistory.size() - 1; i++) {
int x = minX + (maxX - minX) * i / errorHistory.size();
//graph velocity
Brain.Screen.setPenColor(green);
Brain.Screen.drawLine(x, minY + (float)errorHistory.at(i) / goal * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), minY + (float)errorHistory.at(i + 1) / goal * (maxY - minY));
//graph power
//change color based on direction
if (powerHistory.at(i) > 0) {
Brain.Screen.setPenColor(orange);
} else {
Brain.Screen.setPenColor(yellow);
}
Brain.Screen.drawLine(x, maxY - std::abs(powerHistory.at(i)) * (maxY - minY), x + (float)(maxX - minX) / errorHistory.size(), maxY - std::abs(powerHistory.at(i + 1)) * (maxY - minY));
}
}
void drawRobotPath(std::vector<int> x, std::vector<int> y) {
//draws the path of the robot (as discerned from odometry) on the brain of the robot
Brain.Screen.clearScreen();
Brain.Screen.setPenWidth(1);
Brain.Screen.setPenColor(green);
Brain.Screen.drawLine(0, 120, 480, 120);
Brain.Screen.drawLine(240, 0, 240, 240);
Brain.Screen.setPenColor(white);
Brain.Screen.setPenWidth(2);
int originX = 240;
int originY = 120;
float scale = 2;
for (int i = 0; i < x.size() - 1; i++) {
Brain.Screen.drawLine(x.at(i) * scale + originX, 240 - (y.at(i) * scale + originY), x.at(i + 1) * scale + originX, 240 - (y.at(i + 1) * scale + originY));
}
//draw robot as dot
Brain.Screen.setPenColor(red);
Brain.Screen.drawCircle(x.at(x.size() - 1) * scale + originX, 240 - (y.at(x.size() - 1) * scale + originY), 5);
}
/*template for a thread/task (task is a higher level abstraction of thread):
int myTaskCallback() {
while (true) {
//do something
wait(25, msec);
}
// A task's callback must return an int, even though the code will never get
// here. You must return an int here. Tasks can exit, but this one does not.
return 0;
}
in some other function like main():
task myTask = task(myTaskCallback);
*/
void driveCode() {
//drives the robot around based on controller input, double arcade controls
//don't drive if the robot is currently being controlled autonomously
if (auton) return;
Left1.spin(forward);
Left2.spin(forward);
Left3.spin(forward);
Right1.spin(forward);
Right2.spin(forward);
Right3.spin(forward);
int forward1 = Controller1.Axis3.value();
int turn = Controller1.Axis1.value();
//fix drift
if (std::abs(forward1) < 7) forward1 = 0;
if (std::abs(turn) < 7) turn = 0;
//calculate proper motor powers
int left;
int right;
int curveTime = 0;
if (curveDrive) {
//curvature drive, yay
//adjust the straight variable to be non-linear
/*
if (turn < 10 && turn > -10) {
turn = 0; //fix drift
} else if (turn < 60 && turn > -60) {
turn = (turn / 2) + 10; //fine control for small movements
} else {
turn = (turn * 3 / 2) - 50; //full power at higher throttles
}*/
//adjust the turn variable based on the straight one
if (forward1 > 50) {
turn *= (((forward1 - 50) / 50) + 1);
} else if (forward1 < -50) {
turn *= (((-50 - forward1) / 50) + 1);
}
//Inverse Inertia accumulator--slow down fast turns after 200 ms
if (turn < 50 && turn > -50) {
curveTime = 0;
}
if (curveTime > 200) {
turn *= 0.6;
}
//slow down turn:
turn *= 0.7;
curveTime += 20;
}
left = forward1 * driveSpeed + turn * turnSpeed;
right = forward1 * driveSpeed - turn * turnSpeed;
//set velocity of drive motors
Left1.setVelocity(left, percent);
Left2.setVelocity(left, percent);
Left3.setVelocity(left, percent);
Right1.setVelocity(right, percent);
Right2.setVelocity(right, percent);
Right3.setVelocity(right, percent);
}
int drivePID() {
//drive straightforward with driveDistance as the distance, in degrees (for now)
//forward PID constants:
float kP1 = 0.0016;//.003 and 0 for other two
float kI1 = 0.0001;
float kD1 = 0.012;
//0.0027, 0.0001, and 0.015 with 0.08 slew rate was Brighton values
//turning PID constants:
float kP2 = 0.02;
float kI2 = 0.00;
float kD2 = 0.00;
//other variables for forward PID
float error1 = 0;
float integral1 = 0;
float derivative1 = 0;
float prevError1 = 0;
//other variables for turn PID
float error2 = 0;
float integral2 = 0;
float derivative2 = 0;
float prevError2 = 0;
//motor power variables
float motorPower = 0;
float prevMotorPower = 0;
float headingPower = 0;
//lists
std::vector<int> errorHistory; //keep track of error over time
std::vector<float> powerHistory; //keep track of motor power over time
int time1 = 0;
float currentDist = 0; //the distance the robot is from its starting point
float startDist = Inertial.rotation(degrees);
Right1.setPosition(0, degrees);
Right2.setPosition(0, degrees);
Right3.setPosition(0, degrees);
Left1.setPosition(0, degrees);
Left2.setPosition(0, degrees);
Left3.setPosition(0, degrees);
while(true) {
currentDist = (Right1.position(degrees) + Left1.position(degrees) + Right2.position(degrees) + Left2.position(degrees) + Right3.position(degrees) + Left3.position(degrees)) / 6;
//calculate error / integral / derivative, of error vs time graph
error1 = driveDistance - currentDist;
if (std::abs(error1) < 200) {
//weigh the integral double when error < 50
if (std::abs(error1) < 50) {
integral1 += error1 * 2;
} else {
integral1 += error1;
}
}
derivative1 = error1 - prevError1;
//heading correction
error2 = Inertial.rotation(degrees) - startDist;
if (std::abs(error1) < 600) error2 = 0;
integral2 += error2;
derivative2 = error2 - prevError2;
//core of the PID loop here, calculate the necessary motor power, combine both PID loops
motorPower = (kP1 * error1 + kI1 * integral1 + kD1 * derivative1);
headingPower = kP2 * error2;
///keep motor power variable in proper range, -1 to 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
//control the slew rate (dampen voltage differences), limits harsh acceleration
float slewRate = 0.05f;
if (motorPower > prevMotorPower + slewRate) motorPower = prevMotorPower + slewRate;
if (motorPower < prevMotorPower - slewRate) motorPower = prevMotorPower - slewRate;
//account for heading correction P loop
float leftMotorPower = motorPower - headingPower;
float rightMotorPower = motorPower + headingPower;
if (leftMotorPower > 1) leftMotorPower = 1;
if (leftMotorPower < -1) leftMotorPower = -1;
if (rightMotorPower > 1) rightMotorPower = 1;
if (rightMotorPower < -1) rightMotorPower = -1;
//apply motor voltages
Left1.spin(forward, 11 * leftMotorPower * speedPID, volt);
Left2.spin(forward, 11 * leftMotorPower * speedPID, volt);
Left3.spin(forward, 11 * leftMotorPower * speedPID, volt);
Right1.spin(forward, 11 * rightMotorPower * speedPID, volt);
Right2.spin(forward, 11 * rightMotorPower * speedPID, volt);
Right3.spin(forward, 11 * rightMotorPower * speedPID, volt);
//update final variables
prevMotorPower = motorPower;
prevError1 = error1;
prevError2 = error2;
//update histories
errorHistory.push_back(error1);
powerHistory.push_back(std::abs(motorPower));
time1 += 20;
//break out of the loop if we have reached the target or B is pressed
//we have reached the target if the error is less than 5 and the previous error is similar
if (Controller1.ButtonB.pressing() || exitPID || ((std::abs(error1) < 8) && std::abs(error1 - prevError1) < 2)) {
break;
}
graphPID(errorHistory, powerHistory, driveDistance, error1, time1);
//don't hog CPU
wait(20, msec);
}
wait(20, msec); //allow time for status update to draw itself
//graph the PID at the end
drawMode = 1;
graphPID(errorHistory, powerHistory, driveDistance, error1, time1);
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
return 0;
}
int turnPID(bool absolute) {
//drive straightforward with driveDistance as the distance, in degrees (for now)
//forward PID constants:
//zieger-nicholas on 11/14: ku = .07 period = .5 sec
float kP1 = 0.018;//.0245;//.0225 and 0 for other two
float kI1 = 0.0034;//0.0017; //0.0017 //0.0034
float kD1 = 0.12;//0.06;//0.010;
//not bad; 0.024, 0.0034, .15 (1/4/23)
//other variables for forward PID
float error = 0;
float integral = 0;
float derivative = 0;
float prevError = 0;
//motor power variables
float motorPower = 0;
float prevMotorPower = 0;
//lists
std::vector<int> errorHistory; //keep track of error over time
std::vector<float> powerHistory; //keep track of motor power over time
int time = 0;
float currentDist = 0; //the distance the robot is from its starting point, rotationally
float startDist = Inertial.rotation(degrees);
//Inertial1.setHeading(0, degrees);
//Inertial2.setHeading(0, degrees);
//float degOffset
while(true) {
//float deg1 = Inertial1.heading(degrees);
currentDist = Inertial.rotation(degrees) / -1 + startDist;
//Inertial2 is much more accurate than inertial1 (10 spins, 23 degress off vs 5 degrees off)
//printController(Inertial1.rotation(degrees));
//calculate error / integral / derivative, of error vs time graph
error = driveDistance - currentDist;
if (absolute) error = driveDistance + Inertial.rotation(degrees);
if (std::abs(error) < 10) {
//weigh the integral double when error < 4
if (std::abs(error) < 4) {
integral += error * 2;
} else {
integral += error;
}
} else {
integral = 0;
}
if (error > 0 != prevError > 0) integral = 0;//reset integral value if you just crossed the target line
derivative = error - prevError;
//core of the PID loop here, calculate the necessary motor power, combine both PID loops
motorPower = (kP1 * error + kI1 * integral + kD1 * derivative);
///keep motor power variable in proper range, -1 to 1
if (motorPower > 1) motorPower = 1;
if (motorPower < -1) motorPower = -1;
//control the slew rate (dampen voltage differences), limits harsh acceleration
float slewRate = 0.08;
if (motorPower > prevMotorPower + slewRate) {
motorPower = prevMotorPower + slewRate;
}
if (motorPower < prevMotorPower - slewRate) {
motorPower = prevMotorPower - slewRate;
}
//minimum voltage of 11V * .2
/*if (std::abs(slewRate) != .12) {
if (std::abs(motorPower) < 0.2) {
if (motorPower > 0) {
motorPower = 0.2;
} else {
motorPower = -0.2;
}
}
}*/
//apply motor voltages
Left1.spin(forward, 11 * motorPower * -1, volt);
Left2.spin(forward, 11 * motorPower * -1, volt);
Left3.spin(forward, 11 * motorPower * -1, volt);
Right1.spin(forward, 11 * motorPower, volt);
Right2.spin(forward, 11 * motorPower, volt);
Right3.spin(forward, 11 * motorPower, volt);
//update histories
errorHistory.push_back(error);
powerHistory.push_back(motorPower);
time += 20;
//update final variables
//printController(error);
//break out of the loop if we have reached the target or B is pressed
//we have reached the target if the error is less than 5 and the previous error is similar
if (absolute) {
if (Controller1.ButtonB.pressing() || exitPID || ((std::abs(error) < 0.4) && std::abs(error - prevError) < 1)) {
break;
}
} else {
if (Controller1.ButtonB.pressing() || exitPID || ((std::abs(error) < 0.5) && std::abs(error - prevError) < 2)) {
break;
}
}
prevMotorPower = motorPower;
prevError = error;
graphPID(errorHistory, powerHistory, driveDistance, error, time);
//don't hog CPU
wait(20, msec);
}
wait(20, msec); //allow time for status update to draw itself
//graph the PID at the end
drawMode = 1;
graphPID(errorHistory, powerHistory, driveDistance, error, time);
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
return 0;
}
void aDrive(float distance) {
driveDistance = distance;
drivePID();
}
void aTurn(float distance) {
driveDistance = distance;
turnPID(false);
}
void aDriveFor(int speed, int time) {
//drive the robot forward (or backward if speed is negative) for a specified amount of milliseconds
Left1.spin(forward);
Left2.spin(forward);
Left3.spin(forward);
Right1.spin(forward);
Right2.spin(forward);
Right3.spin(forward);
Left1.setVelocity(speed, percent);
Left2.setVelocity(speed, percent);
Left3.setVelocity(speed, percent);
Right1.setVelocity(speed, percent);
Right2.setVelocity(speed, percent);
Right3.setVelocity(speed, percent);
wait(time, msec);
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
}
//below code copied from jpearman on vexforum
int screen_origin_x = 150;
int screen_origin_y = 20;
int screen_width = 316;
int screen_height = 212;
// function to draw a single object
void drawObject( vision::object &obj, vex::color c ) {
int labelOffset = 0;
Brain.Screen.setPenColor( vex::color::yellow );
Brain.Screen.drawRectangle( screen_origin_x + obj.originX, screen_origin_y + obj.originY, obj.width, obj.height, c );
Brain.Screen.setFont( vex::fontType::mono12 );
if( obj.originX > 280 )
labelOffset = -40;
if( obj.originY > 10 )
Brain.Screen.printAt( screen_origin_x + obj.originX + labelOffset, screen_origin_y + obj.originY-3, "Sig %o", obj.id );
else
Brain.Screen.printAt( screen_origin_x + obj.originX + labelOffset, screen_origin_y + obj.originY+10, "Sig %o", obj.id );
}
// function to draw all objects found
void drawObjects( vision &v, vex::color c, bool clearScreen ) {
if( clearScreen ) {
Brain.Screen.setPenColor( vex::color::black );
Brain.Screen.drawRectangle( screen_origin_x, screen_origin_y, screen_width, screen_height, vex::color::black );
}
for(int i=0;i<v.objectCount;i++)
drawObject( v.objects[i], c );
}
void autonomousProgramTask(void) {
auton = true;
//wait until inertial is calibrated
while (Inertial.isCalibrating()) {
wait(30, msec);
printControllerSetup();
Controller1.Screen.print("Calibrating Inertial");
}
float timerValue = Brain.Timer.value();
//run the autonomous program based on the autonType variable
//Auton 0: Testing Auton
if (autonType == 0) {
aTurn(90);
}
else if (autonType == 1) { //Auton 1: AWP (mostly) autonomous, near side,
//start out by lowering intake and scraper
Scraper.set(true);
Intake.spin(reverse, 5, volt);
//get triball out of match load zone
aTurn(35);
Scraper.set(false);
driveDistance = 153;
turnPID(true);
Intake.stop();
//shove alliance triball preload into goal
wait(100, msec);
Intake.spin(forward, 11, volt);
wait(70, msec);
aDriveFor(40, 100);
aDriveFor(80, 800);
aDriveFor(40, 300);
Intake.stop();
wait(200, msec);
//back up and drive to the elevation bar
aDrive(-1000);
aTurn(-135);
wait(100, msec);
aDrive(1110);
driveDistance = 45;
turnPID(true);
turnPID(true);
Intake.spin(forward, 5, volt);
//go forward the right distance, based on the distance sensor.
aDrive(1650);
if (WallDistance.objectDistance(inches) < 55){
aDrive(100);
}
Intake.stop();
} else if (autonType == 2) { //Auton 1: far side, standard one
//collect green triball under elevation bar
Intake.spin(reverse, 11, volt);
wait(800, msec);
Intake.spin(reverse, 4, volt);
//back up to goal
aDrive(-1870);
aTurn(38);
wait(100, msec);
aDrive(-1170);
aTurn(40);
aDriveFor(-40, 100);
aDriveFor(-80, 500);
aDriveFor(-40, 100);
wait(200, msec);
//go forward, turn around, and push other triball into the goal
aDrive(300);
driveDistance = -90;
turnPID(true);
Intake.spin(forward, 11, volt);
wait(200, msec);
aDriveFor(40, 100);
aDriveFor(80, 400);
aDriveFor(40, 100);
Intake.stop();
wait(100, msec);
//back up, to get other triballs
aDrive(-400);
driveDistance = -13;
turnPID(true);
//get the triball NOT on the middle line
Intake.spin(reverse, 11, volt);
aDrive(2750);
//go get triball near the very center of field
aTurn(-60);
Intake.spin(reverse, 4, volt);
aDrive(1200);
aTurn(-96);
//push the three triballs into the goal
Wings1.set(true);
Wings2.set(true);
wait(100, msec);
Intake.spin(forward, 11, volt);
aDriveFor(20, 100);
aDriveFor(50, 200);
Intake.stop();
aDriveFor(100, 500);
wait(400, msec);
aDriveFor(70, 600);
} else if (autonType == 3) {
//start out by lowering intake and scraper
Scraper.set(true);
Intake.spin(reverse, 5, volt);
//get triball out of match load zone
wait(400, msec);
aTurn(35);
Scraper.set(false);
driveDistance = 153;
turnPID(true);
Intake.stop();
//shove alliance triball preload into goal
wait(100, msec);
wait(70, msec);
aDrive(1000);
Intake.spin(forward, 11, volt);
wait(1500, msec);
Intake.stop();
wait(50, msec);
//back up and drive to the elevation bar
aDrive(-1400);
driveDistance = 0;
turnPID(true);
turnPID(true);
wait(100, msec);
aDrive(100);
driveDistance = 45;
turnPID(true);
turnPID(true);
Intake.spin(forward, 5, volt);
//go forward the right distance, based on the distance sensor.
aDrive(1300);
if (WallDistance.objectDistance(inches) < 55){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 55){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 55){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 55){
aDrive(100);
}
Intake.stop();
} else if (autonType == 4) {
//better near side auton
//start out by lowering intake and scraper
Scraper.set(true);
Intake.spin(reverse, 11, volt);
//get triball out of match load zone
aTurn(35);
Scraper.set(false);
driveDistance = 114;
turnPID(true);
Intake.spin(reverse, 5, volt);
//push preload in goal
aDrive(2400);
driveDistance = 215;
turnPID(true);
Intake.spin(forward, 11, volt);
wait(500, msec);
Intake.stop();
//push two green triballs onto the other offensive zone
driveDistance = 100;
turnPID(true);
Intake.spin(reverse, 11, volt);
aDrive(350);
Intake.spin(reverse, 7, volt);
aTurn(-60);
Intake.stop();
Wings1.set(true);
Wings2.set(true);
Intake.spin(forward, 11, volt);
aDrive(1080);
aDriveFor(70, 300);
Wings1.set(false);
Wings2.set(false);
wait(100, msec);
//go to elevation bar
driveDistance = -87;
turnPID(true);
Intake.stop();
aDrive(3000);
aTurn(115);
Intake.spin(forward, 11, volt);
aDrive(2200);
Intake.stop();
Intake.spin(forward, 5, volt);
//go forward the right distance, based on the distance sensor.
if (WallDistance.objectDistance(inches) < 54){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 54){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 54){
aDrive(100);
}
if (WallDistance.objectDistance(inches) < 54){
aDrive(100);
}
Intake.stop();
} else if (autonType == 5) {
//programming skills
//intitial setup
aDrive(-700);
driveDistance = 60;
turnPID(true);
//match loading
kickerOn = true;
turnPID(true);
speedPID = 1;
wait(24, sec);
Controller1.rumble(rumbleShort);
wait(3, sec);
//turn and drive
kickerOn = false;
aTurn(-55);
aDrive(1450);
driveDistance = -138;
turnPID(true);
turnPID(true);
aDrive(-4100); //drive under elevation bar
aTurn(25);
aDrive(-1500);
aTurn(50);
//push triballs in goal
aDriveFor(-20, 200);
aDriveFor(-50, 300);
aDriveFor(-100, 400);
wait(300, msec);
//line up for main push on right
aDrive(400);
driveDistance = -146;
turnPID(true);
turnPID(true);
aDrive(2300);
aTurn(-75);
aDrive(900);
driveDistance = -296;
turnPID(true);
turnPID(true);
//main push on right
Wings1.set(true);
Wings2.set(true);
wait(200, msec);
aDriveFor(20, 300);
aDriveFor(50, 200);
aDriveFor(100, 1000);
wait(300, msec);
Wings1.set(false);
Wings2.set(false);
//Line up for second main push (left)
driveDistance = -310;
turnPID(true);
aDrive(-1300);
driveDistance = -390;
turnPID(true);
aDrive(-1600);
driveDistance = -340;
turnPID(true);
turnPID(true);
Wings1.set(true);
Wings2.set(true);
aDriveFor(20, 300);
aDriveFor(50, 200);
aDriveFor(100, 700);
wait(300, msec);
//try and get any more, if possible; back up and spin
aDrive(-1300);
//third go
aDriveFor(20, 300);
aDriveFor(50, 200);
aDriveFor(100, 500);
wait(300, msec);
}
printController(Brain.Timer.value() - timerValue);//print time it took
auton = false;
}
int autonomousProgram() {
autonomousProgramTask();
return 0;
}
void autonomousProgramWrapper(void) {
autonTask = task(autonomousProgram);
}
void buttonBPressed() {
//prints out a bunch of useful information on the brain screen--a status check
Brain.Screen.clearScreen();
Brain.Screen.setCursor(1, 1);
Brain.Screen.print("Battery voltage: ");
Brain.Screen.print(Brain.Battery.voltage());
Brain.Screen.newLine();
Brain.Screen.print("Battery current: ");
Brain.Screen.print(Brain.Battery.current());
Brain.Screen.newLine();
Brain.Screen.print("Left Motors temp: ");
Brain.Screen.print(Left1.temperature(percent));
Brain.Screen.print(" ");
Brain.Screen.print(Left2.temperature(percent));
Brain.Screen.print(" ");
Brain.Screen.print(Left3.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Right motors temp: ");
Brain.Screen.print(Right1.temperature(percent));
Brain.Screen.print(" ");
Brain.Screen.print(Right2.temperature(percent));
Brain.Screen.print(" ");
Brain.Screen.print(Right3.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.print("Kicker temp: ");
Brain.Screen.print(Kicker.temperature(percent));
Brain.Screen.newLine();
Brain.Screen.newLine();
autonTask.stop();
auton = false;
}
void buttonYPressed() {
//start autonomous if A is held down while pressing Y
if (Controller1.ButtonA.pressing()) {
autonomousProgramWrapper();
} else {
autonType++;
if (autonType > 7) autonType = 0;
printControllerSetup();
Controller1.Screen.print("Auton type: ");
Controller1.Screen.print(autonType);
}
}
void buttonXPressed() {
//turn on or off the kicker
kickerOn = !kickerOn;
if (kickerOn) {
KickerLED.on();
} else {
KickerLED.off();
Kicker.stop();
}
}
void buttonR2Pressed() {
wingsActive = !wingsActive;
if (wingsActive) {
Wings1.set(true);
Wings2.set(true);
} else {
Wings1.set(false);
Wings2.set(false);
}
}
void buttonL1Pressed() {
Intake.spin(forward, 11, volt);
}
void buttonL1Released() {
Intake.stop();
}
void buttonL2Pressed() {
Intake.spin(reverse, 11, volt);
intakeOn = true;
if (Controller1.ButtonB.pressing()){
curveDrive = !curveDrive;
if (curveDrive) {
printControllerSetup();
Controller1.Screen.print("Curve Drive Active");
} else {
printControllerSetup();
Controller1.Screen.print("Linear Drive Active: ");
}
}
}
void buttonL2Released() {
Intake.stop();
intakeOn = false;
}
void buttonUpPressed() {
elevationActive = !elevationActive;
if (elevationActive) {
ElevationPiston.set(true);
} else {
ElevationPiston.set(false);
}
}
void buttonDownPressed() {
scraperActive = !scraperActive;
if (scraperActive) {
Scraper.set(true);
} else {
Scraper.set(false);
}
}
void buttonLeftPressed() {
//recalibrate inertial
Inertial.calibrate();
int calibrateTimer = 0;
while (calibrateTimer < 200) {
if (!Inertial.isCalibrating()) {
printControllerSetup();
Controller1.Screen.print("Recalibrated");
break;
}
calibrateTimer++;
wait (20, msec);
}
}
void setLeftDrive(int velocity1) {
Left1.setVelocity(velocity1, percent);
Left2.setVelocity(velocity1, percent);
Left3.setVelocity(velocity1, percent);
}
void setRightDrive(int velocity1) {
Right1.setVelocity(velocity1, percent);
Right2.setVelocity(velocity1, percent);
Right3.setVelocity(velocity1, percent);
}
void buttonRightPressed() {
//Automatically balance the robot
ElevationPiston.set(true);
auton = true;
Left1.spin(forward);
Left2.spin(forward);
Left3.spin(forward);
Right1.spin(forward);
Right2.spin(forward);
Right3.spin(forward);
setLeftDrive(90);
setRightDrive(90);
wait(200, msec);
setLeftDrive(40);
setRightDrive(50);
wait(400, msec);
setLeftDrive(40);
setRightDrive(-80);
wait(200, msec);
Left1.stop();
Left2.stop();
Left3.stop();
Right1.stop();
Right2.stop();
Right3.stop();
auton = false;
}
void checkOverheating() {
//check for overheating in any of the motors
if (Left1.temperature(percent) > 60 || Left2.temperature(percent) > 60 || Left3.temperature(percent) > 60 || Right1.temperature(percent) > 60 || Right2.temperature(percent) > 60 || Right3.temperature(percent) > 60 || Kicker.temperature(percent) > 60) {
if (overHeatingTimer == 0) {
Controller1.rumble(rumbleLong);
printControllerSetup();
Controller1.Screen.print("Real Overheating Warning");
overHeatingTimer++;
} else {
overHeatingTimer++;
if (overHeatingTimer > 750) overHeatingTimer = 0;
}
}
}
int kickerLoop() {
//shoot the kicker when there is a triball and keep it loaded at all times
bool reachedBottom = false;
while (true) {
//check if it is optical sensor mode
wait(20, msec);
if (kickerOn) {
KickerLED.on();
if (KickerDrawback.objectDistance(mm) < 90) {
if (KickerDistanceSensor.objectDistance(mm) < 40) {
//triball detected
Kicker.spin(reverse, 11, volt);
} else {
//no triball detected
Kicker.stop();
}
reachedBottom = true;
} else {
Kicker.spin(reverse, 11, volt);
reachedBottom = false;
}
} else {
Kicker.stop();
KickerLED.off();
}
}
return 0;
}
int intakeLoop() {
//spin at 3 volts when the efficency is 0
while (true) {
//check if the intake is on
wait(20, msec);
if (intakeOn) {
if (Intake.efficiency(percent) < 10) {
//if the intake is on and efficency is low, there is likely a triball in there; reduce the voltage to lower strain on the motor
Intake.spin(reverse, 2, volt);
} else {
//otherwise, spin normally
Intake.spin(reverse, 11, volt);
}
}
}
return 0;
}
void init() {
//initialize settings, variables, and callback functions
Kicker.setStopping(coast);
Left1.setStopping(coast);
Left2.setStopping(coast);
Left3.setStopping(coast);
Right1.setStopping(coast);
Right2.setStopping(coast);
Right3.setStopping(coast);
KickerLED.off();
//other functions
Controller1.ButtonX.pressed(buttonXPressed);
Controller1.ButtonY.pressed(buttonYPressed);
Controller1.ButtonR2.pressed(buttonR2Pressed);
Controller1.ButtonB.pressed(buttonBPressed);
Controller1.ButtonL1.pressed(buttonL1Pressed);
Controller1.ButtonL1.released(buttonL1Released);
Controller1.ButtonL2.pressed(buttonL2Pressed);
Controller1.ButtonL2.released(buttonL2Released);
Controller1.ButtonUp.pressed(buttonUpPressed);
Controller1.ButtonDown.pressed(buttonDownPressed);
Controller1.ButtonLeft.pressed(buttonLeftPressed);
Controller1.ButtonRight.pressed(buttonRightPressed);
//start task
task myTask2 = task(kickerLoop);
task myTask3 = task(intakeLoop);
}
void pre_auton(void) {
init();
Inertial.calibrate();
}
void usercontrol(void) {
auton = false;
while (1) {
driveCode();
wait(20, msec);
}
}
int main() {
// Initializing Robot Configuration. DO NOT REMOVE!
vexcodeInit();
// Set up callbacks for autonomous and driver control periods.
Competition.autonomous(autonomousProgramTask);
Competition.drivercontrol(usercontrol);
// Run the pre-autonomous function, basically initialize
pre_auton();
// Prevent main from exiting with an infinite loop.
while (true) {
checkOverheating();
//printController(Intake.efficiency(percent));
wait(20, msec);
}
}


Design Constraints
Design Constraints
The robot has to be built according to the rules and constraints that the REC foundation lists in the game manual. Some of these robot design constraints are listed:
   * Robots must start the match no larger than an 18” by 18” by 18” cube.
   * Robots must be built from VEX official metal, motors, microcontrollers, and wires.
   * Robots can use limited polycarbonate; the maximum amount is that which could be cut from a single 12” by 24” sheet up to 0.070” thick.
   * Robots can use no more than 88W of total motor power--large motors are 11W each and small motors are 5.5W each.
   * Robots can use no more than 2 pneumatic air tanks (unlimited pneumatic pistons).
   * Robots must have license plates with a clearly identifiable team number.


Game Analysis Over Under
Game Analysis
Now, we will analyze the game to explore what an effective robot design will be able to do, so we can design our robot accordingly.
Initial Thoughts
This game has many interesting features, that distinguish if from previous challenges:
   * About 74% (44 / 60) of the primary game objects are match loads. This means that efficient match loading will be key to success.
   * There is a large barrier in the middle of the field. Going over this barrier will most likely be a huge advantage, as it allows for better maneuverability around the field.
   * The highest elevation tier is above the height of the elevation bar, so reaching it will require an alliance partner with a compatible design.
   * Since the AWP tasks require both removing a triball from the match load zone and scoring an alliance triball in an alliance’s goal, and crossing to the opposing offensive zone is not permitted during autonomous, no solo AWP program is possible this year. Both robots will have to be able to complete their respective tasks for that alliance to earn the AWP.
Scoring Analysis
Points can be obtained from one of three methods:
   1. 1.
Alliance Triballs can be scored in an offensive zone for 2 points each or a goal for 5 points each
   2. 2.
Elevating gives between 5 and 20 points, based on the relative elevation tier of the robot.
   3. 3.
The winner of the Autonomous Bonus earns 8 points.
Here is a breakdown of the points earned from a single object (where applicable) for each of the scoring methods.
  

We can observe that elevation gives the most points, and triballs in offensive zones give the least amount of points.
However, we also have to consider the total score:
      * There are 60 triballs, and all 60 can be scored in an offensive zone for 120 points
      * Around 40 triballs can fit in a goal, for a total of 200 points
      * Elevating at the highest tier results in 20 points
      * The Autonomous Bonus gives 8 points
  

In terms of total score, triballs scored in goals give the most points and the Autonomous Bonus and elevation give the least amount of points.
Strategy Analysis
Here we will list potential strategies of a single robot and analyze the advantages and disadvantages of each one.
Push triballs into the goal
Advantages
	Disadvantages
	      * 
Scores 5 points for each triball pushed in
      * Makes it harder for the opposing alliance to descore the triballs
	         * 
Triballs can be descored if one’s alliance is double-zoned
         * Only a net gain of 3 points if the triballs are already in one’s offensive zone
	Push triballs into the offensive zone
Advantages
	Disadvantages
	            * 
Scores 2 points per triball
            * If the triball was previously in the other offensive zone, then there is a net gain of 4 points
            * Gets the triball closer to the goal
	               * 
Triballs can be descored very easily
               * The barrier may prevent pushing triballs across the center of the field
	Elevate at the end of the match
Advantages
	Disadvantages
	                  * 
Worth more points if the robot is higher than all other robots
                  * Relatively quick method of scoring
	                     * 
Only practical in the last 10 seconds of the match.
                     * Gives opponents a chance to score more triballs uncontested
	Launch match load triballs over the barrier
Advantages
	Disadvantages
	                        * 
Scores 2 points per triball
                        * Uses match loads effectively
                        * Allows alliance partner to score these triballs in the goal more easily
	                           * 
Defense may prevent easy loading of triballs onto the robot
                           * Triballs may be descored by the opposing alliance
	Defend opponent robots that are scoring triballs in goals
Advantages
Disadvantages
Prevents opposing alliance from scoring easily
Can simultaneously push triballs to the offensive zone for 2 points
Potential SG8.b rule violation
Less time to score triball in one’s own goal or elevate
Push opponent robots onto the barrier
Advantages
Disadvantages
Disrupts the opponents from scoring quickly
Has a chance of legally getting the opponent robot stuck
Less time for offensive gameplay
Robot has a chance of getting stuck on the barrier
Descore triballs from the opponent’s goal
Advantages
	Disadvantages
	                              * 
Has the potential to descore many points from the opposing alliance
                              * Can be done fairly quickly, leaving time for other aspects of the game
	                                 * 
Only permissible if the opposing alliance is double-zoned
                                 * Triballs still end up on the opponents offensive zone, and count for 2 points for the other team.
	

Over Under Rules
Game Introduction
The game for this year is VEX Over Under!
  

*All images in this section are from the VEX Over Under Game Manual and property of the RECF
Goals in VEX Over Under:
                                    * Score triballs in goals or offensive zones.
                                    * Elevate your robot at the end of the match
                                    * Prevent the opposing alliance from scoring points.
The primary game objects are triballs:
                                    * Height : 6.18”
                                    * Width: 6.18”
                                    * Weight: 110 ± 20 grams
                                    * Outer diameter: 7.00”
  

  

Triballs can be scored as such:
Triball scored in Goal
	5 points
	Triball scored in Offensive Zone
	2 points
	Next, Goals, where triballs can be scored, have the following dimensions:
                                    * Width: 23.08”
                                    * Length: 47.13”
                                    * Height: 5.78”
  

  

One important implication is that the triballs are taller than the height of the goal, so the bars on the goal will have to flex upwards slightly for the triballs to go into the goal.
Next, we have the Elevation Bars; an alliance can Elevate at the end of match on these to gain extra points:
  

Dimensions of the Elevation Bars:
                                    * Outer diameter: 2.38”
                                    * Height of horizontal bar: 11.63” from the ground
                                    * Height of vertical bar: 30.23”
                                    * Horizontal bar length: 21.89”
The Barrier also presents an additional obstacle for navigating the field, and is divided into the short barrier and the long barrier.
  

The barrier is constructed out of 2.38” OD PVC pipe raised 0.5” above the field tiles.
The Match Load Bars separate the match load zone from the rest of the field:
  

Note that the bars have the same outer diameter as the barrier and the elevation bars, 2.38”
The Autonomous Line marks the edges of the neutral zone. It is highlighted below:
Game Scoring Definitions
Triballs:
A triball is Scored in a Goal (for 5 points) if at least two of the four “corners” of the triball are within the outer edges of the PVC pipes enclosing the goal.
The triball shaded green is scored, but the one shaded red is not scored because only one corner is within the Goal
A triball is Scored in an Offensive Zone (for 2 points) if it is contacting the gray foam tiles in that Offensive Zone.
Alliance Triballs count as scored for the alliance that they are colored, regardless of which goal or offensive zone they end the match in.
Elevation:
A Robot is Elevated if they are contacting their alliance’s elevation bars or the barrier, or their alliance partner.
A Robot cannot be elevated if they are contacting the gray foam tiles, the field perimeter, or the yellow elevation bar cap.
A Robot is assigned an Elevation Tier based on how high the lowest point on the robot is elevated, as determined using the Height Guide.
The Robot with the highest elevation tier will receive 20 points; the second-highest tier will receive 15 points, and so on:
The Height Guide along with accompanying measurements for each Elevation Tier ↗
Autonomous:
The alliance that scores more points during the Autonomous Period (0:15) will earn an additional Autonomous Bonus of 8 points going into the Driver controlled period (1:45). Elevation points do not count towards determining the winner of the Autonomous Bonus.
If an alliance:
Removes the triball from that alliance’s math load zone that coincides with their starting tiles
Scores at least one alliance triball in their own goal
Touches their own elevation bar at the end of the autonomous period
Then they can earn an Autonomous Win Point (AWP), which counts as half of a win in the ranking system.
Specific Game Rules
<SG1> Robots must be placed on the starting tiles below, and not contacting the barrier, another robot, or any green triballs.
<SG2> Robots may not horizontally expand more than 36” at any point during the match.
<SG3> Triballs should stay in the field. Any triball that comes to rest on the net of a goal may be removed and used as a match load.
<SG4> Each robot gets one alliance triball as a preload.
<SG5> Robots that become entangled in the net will be disabled.
<SG6> Match loads may be introduced by:
Placing them into the match load zone
Placing them onto a robot that is contacting the match load bar
<SG7> Possession is limited to 1 triball.
<SG8> When the opposing alliance is double-zoning, robots are permitted to go under the opposing alliance’s goal.
An alliance is double-zoned if both robots are contacting the gray foam tiles within a single offensive zone, and neither one is contacting the long barrier.
In this picture, the red alliance is double-zoned since both robots are in the same offensive zone, and the blue alliance can go under the red goal to descore triballs.
<SG9> Robots are not permitted to contact the gray foam tiles on the opposite side of the location that they start the match in during the autonomous period.
<SG10> Teams are responsible for the actions of their robots at all times, even in interactions with other robots in the neutral zone during autonomous.
<SG11> Robots may not contact opposing robots or the opposing alliance’s elevation bars during the last 30 seconds of the match.