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How can I control the position of a pneumatic piston?
The only way I know about is using a magnetic reed switch (magnetic sensor) with a matching piston and use some type of control algorithm, like PID for instance, to keep the piston where the sensor is.
The problem with that is that it gives you only limited control of the position, it just adds another "state" (open, closed, sensor position) and not full control. for example I want it to be 43% once and 70% the other time, but without using a sensor for each position because I would like all the "options" to be available (I mean that the percentages aren't pre-defined)
This is an example of the pistons I use:
This is a good example of what I want: http://www.youtube.com/watch?v=A8LZ15uiuXU
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Where can I find a good documentation about the UWSim in ROS. Actually having the source files is not enough and it is actually hard to follow all the functions. for example, how can I use these command correctly :
& rosrun UWSim gotoAbsolutePosition 0 0 0 0 0 0
I know that there is a node 'gotoAbsolutePosition' in the Package 'UWSim' and I knwo the variables, but I cannot set the two topics properly.
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I'm building quadcopter and most of the control systems use one accelerometer and gyro. I've read few papers and usually accelerometer is used as reference to the ground because gyro slowly drifts away in time. But if quadcopter does some crazy maneuvering when force direction from accelerometer does not have to point to the ground than accelerometer data is useless. As well there is problem with centripetal force if the accelerometer is not directly in the centor of mass.
I was thinking about using multiple accelerometers. To fully determine position and motion of quadcopter one would need three accelerometers(If I have done the math right). This would kind of solve the problem with centripetal force
So I would like to know if anyone tried to use multiple accelerometers for better orientation estimation.
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So i got this idea waay back when i was in highschool as a kind of electromagnetic analogue to a biological muscle. it is basically a long stack of thin electromagnets connected in parallel.
.
when current is applied gaps between electromagnets shrink thus providing contraction of the whole chain.
I am pretty sure it can work. It can't offer great contraction range (up to 50% i would guess) but it has potential to provide good speed and be compact so that multiple chains can be combined to form stong and fast linear actuators. The thing is, i never heard of this type of actuator being used. so what is the catch? is there a better alternative? is there a design flaw? too much heat generated making them unpractical?
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I'm trying to get the "Torobot" USB servo controller to work with Angstrom Linux on a Beagle Board XM.
The servo controller registers as a USB device. The device just takes simple text commands, but there is no TTY associated with it. So I'm not sure how to send commands to it.
Can I just send data like this (assuming that 002/005 is the device):
$ cat file.txt >> /dev/bus/usb/002/005
Or do I need to associate it with the generic USB device? If so, how do I do that?
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I am a Robotics enthusiast and planning to make a small and simple four wheel car whose motors are supposed to be controlled by an Android device housed inside the car by means of the micro USB port of the device. The car has to move forward or backward only as directed by the signals from the Android device.
So my assumption is that there should be a circuit board which accepts the signals from the microUSB/USB of the Android device and controls the power to the electric DC motor. Also the power for the motor will be supplied from a battery pack inside the car.
Could anyone suggest me a cheap motor driver circuit which supports micro USB or USB? And where can I get the parts for this online? I did a lot research but very confused with the technical terms which I am not familiar with.
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I consider using a brushless outrunner motor, designed for helicopters, in my driving roboter. How can I control such a brushless motor with my micro controller? Of course I'll have a separate power source.
The roboter should be able to move forwards and backwards, so I need to control the motor in a way to determine direction of rotation, too. I think this isn't related to the question, but I need to ensure high acceleration.
Specially, I am talking about this motor which is listed in a German shop.
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I have a 300cm x 300cm room with a 25cm high ceiling (yes twenty five centimeters). It contains 50 small wheeled robots (about 20cm x 20cm). A central computer will orchestrate the movements of the robots, using a wireless network to send position commands to them. The robots will perform their own closed loop position control to save wireless bandwidth. The robots have 32-bit ARM microcontrollers. They have wheel position sensors, and the ability to do accurate wheel control.
Problem: The robots can't actually do this yet because they have no way to measure their position in the room.
Question: How can the robots be given the ability measure their position and orientation to an accuracy of better than ±5mm? I am looking for an accurate and robust solution, which is not affected by occlusions, and doesn't require a high power PC on each robot. Whatever sensors are necessary for localisation can easily be added to the robots. The microcontrollers can easily be changed for more powerful ones if the localisation solution demands it.
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Outline:
I'm trying to work with an Arduino and Analog thumb stick to get values for a simple differential drive robot I'm working on. The Keyes_Sjoys Arduino Joystick Module I have in my possession is giving me some strange numbers.
Following axises Data I have:
X-axis range of 0 to a shaky 470-520 with a center value of 40.
Y-axis range of a solid 4 to solid 1023 with a center value of 605.
Problem
I haven't used analog sensors before but it seems pretty obvious that my X-axis ranges should feel somewhat similar to the Y-axis but they don't. In addition, the X-axis hits zero way way before even coming close to the edge for its operating range.
Is my sensor broken (it's new), or is there some way I can recalibrate the potentiometer?
Note, I also asked this over on Electrical Engineering Stack Exchange.
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I'm trying to make differential in Google SketchUp using this tutorial http://support.ponoko.com/entries/21249896-Gears-and-Joints-with-SketchUp-Sketchy-Physics for gears modeling.
But I have problem: gears don't collide with any objects (and other gears). What's wrong? How to fix this?
How to make a bevel gear placed at 90 degrees relative to each other and conical cylindrical gears joints?
P.S. Is there something like SketchUp and SketchyPhisics in Linux?
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I need to assemble a small (about 8cm x 5cm x 5cm maximum), actuator with as much torque as I can get at that size. It will be driving a small reel and pulley (reel is ~1.25cm^3, 5mm center diameter), and needs to respond to load (eg. stop if the load increases beyond a certain threshold). Power to the actuator will be provided via a common bus line, so the space limit isn't further limited by the size of the battery.
My thought is to use a worm drive for this (for torque) and watch for change in current/voltage (for load), but I'm not sure if that is mechanically sound. It seems like the mechanical advantage provided by the worm would make it hard to detect a change in load.
Plan B
I could add another sensor that would gauge the force being exerted. I'd prefer to avoid adding too many points of failure to the system, but if I did what sort of sensor would I use?
How should I approach this?
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This question is further to Localizing a swarm of robots.
In summary: I want to create a swarm of robots which can each measure their own position in a 3x2m room with a 25cm high ceiling, to an accuracy of ±5mm.
There were some good answers, but most of them were optical methods. I would be interested to hear some non-optical localisation ideas, so I will impose the following further constraints:
Localisation method cannot use optical means, either visible or invisible.
Nothing can be added to the floor or ceiling.
There's no appreciable gap between the top of the robots and the ceiling.
There are no walls, and equipment can be added around the perimeter of the room.
I look forward to hearing some creative ideas.
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Which software can be used to prototype/design robot parts (mechanical parts, body, gears, etc)>
I have some crazy idea I would like to try (quadripedal walking robot, animal-like), but I'd like to design the mechanism and test (to some degree) the mechanism in some kind of simulator before I start wasting money on parts/materials. What tool could I use for that?
I'm only interested in mechanical design (chassis + servo/motor placement + cogs/gears), not in electronic design. I'm not interesting in robot control software, because I'll be probably able to slap something like arduino onto it and program behavior I want (experienced programmer)
Details (what I'd like to see):
Should work in 3d. I.e. finished system should be viewable in 3d.
I should be able to cut materials like plywood/metal, drill holes, place gears on it, etc.
It would be nice if it had some kind of part catalog so to place a gear/cog I wouldn't need to design it from scratch.
It would be nice I could test if parts can actually move. I don't need full-blown simulation, just to see if gears can turn or if they'll get stuck.
Not interested in electronic circuitry, just need mechanical parts, but should be able to place servos.
It would be nice if it could produce blueprints.
cheap/inexpensive, if possible.
Basically, I should be able to construct robot mechanism in it (by placing/connecting parts like gears,cogs, motors, springs), or some kind of clock, and test (to some degree) if it actually works.
I know that I could use blender3d for that, but it wasn't exactly designed for this purpose.
I also heard that solidworks could be used for designing mechanical parts, but it is too expensive, especially for one-time-project.
Any recommendations?
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I need an equation or a some hints to solve the following problem.
Imagine a roller screw drive. I apply a torque of T to translative move my load mass M. I assume my screw has an efficiency of 90%. Now an additional axial force affects my mass in the opposite moving direction. Is this force completely transformed into torque (of course considering the efficiency) or is it possible, that my whole roller screw is moving, because it is not fixed? I just found papers/books/articles for movable slides/loads, but fixed shafts. But in my case motor and shaft are part of an osciallation system.
I'm not a mechanical engineer, so I'm sorry if the answer may is trivial.
I made a little sketch now
The process force Fp is pushing my mass, most of the force is transformed into a load torque Tp which acts against my drive torque TD. Some of the energy is lost by friction. The question is, if there is also a partial force Tp? which is affecting the bearing and therefore exciting my chassis.
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Today I was going to buy a motor online, and saw that 10 rpm and 1000 rpm DC motors cost the same. How is it possible to change the rpm without requiring any additional parts cost?
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I want to make a mathematical model of quadcopter in simulink. I have studied quadcopter, although I am new and not build any flying robot before. I studied so far that I have to use four brushless DC motors PID speed control, two motors will rotate clock wise and two anti clock wise. I want to make very simple mathematical model.
The input of the model will be the xyz locations on 3d space, copter will always fly from 0,0,0 path.
So far I decided that I will increment the coordinates step by step for example if I want the next location of the to be x=10, y=10, z=10; then I will increment in these locations and input to a flight control block.
My question is how can I decide the speed of motors according to x,y,z next location and how to convert that speed into Yaw Pitch and Roll and finnally convert the Yaw, Pitch and Roll into X,Y,Z coordinates.
I need the convertion formulas that can be easily implemented into simulink.
Please provide help thanks
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I am trying to build an arm that will have about 5 by 5 by maybe 7 or so centimeters of room for a rotary motor capable of lifting it. The joint will basically allow the arm to rotate in a single degree of freedom in a circle that is perpendicular to the ground.The rest of the arm will probably be around 64 centimeters long and weigh around a minimum of 9 kilograms before it lifts anything.
What kind of motor type would give it the best chance of lifting the arm quickly† and reasonably accurately‡?
† Raising from straight down to out 90 degrees in around 1 to .5 seconds maximum.
‡ At least a centimeter at the end of the arm which means probably at the very least 300 positions for the motor.
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I'd like to start with robotics, but unfortunately I know very little about HW engineering. Moreover I used to use such languages as Python, C# and Java, and do not have much experience in C. Still I want very much to be able to program a robot, and I have very big interest in Computer Vision and AI. Are there any platforms/kits that you can buy, and with little time spent you already can program them, preferably in high-order languages?
I'd prefer something wheeled (something flying would also be nice, but it may be too hard to be the case for a first robot), with a camera and some additional sensors. Would be also nice to have there something, that could help to avoid obstacles, like laser distance sensor or ultra-sonic sensor. Ideally I would like to build a robot that can navigate in the room without the help of operator. I'd like to look at SLAM some time in future, but for now I just need something to get familiar with the robotics.
Also it should probably be not very expensive, at least not before I will be very sure that I am ready to go deeper into robotics. Something for 300-500$ would be awesome.
Can somebody suggest kits/platforms/tutorials/any other info?
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I am doing simulation of Quadcopter in simulink. I want to know how Yaw, Pitch and Roll effect the flight of Quadcopter? and How these are different from a single rotor helicopter?
Mainly how to change the RPM to change the x,y,z coordinates of the Quadcopter?
Is there any Differential Equation that can convert the rpm to yaw pitch and roll? Please help.
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I'm new to the whole visual servoing area.
I'm now reading the tutorial Visual Servo Control
Part I: Basic Approaches" and I don't understand something fundamental - what information is available to the robot?
Is the 3D location of the tracked features in the current frame known?
Is it known for the desired frame?
Is it known for both?
If it's known for both - then what would be the best thing to do?
Would it be to compute the current and desired 3D location and orientation of the robot, and plan an optimal path accordingly, essentially knowing everything in advance?
Also, in what sense could a control law (i.e translation + rotation path) be optimal for a visual servo?
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My quad copter can balance itself in the air using data collected from mpu6050. With the sonar sensor, it can hover at a specific height, but it moves on the horizontal plane in a random direction. If i put an object below it, it will ascend to keep the distance between the sonar senor and the object.
Now i want to make it have the ability to hover stably. Is it possible to add a downward-facing camera to calculate the speed of optical flow in order to keep it hovering on the same point in the horizontal plane? Could I use a forward-facing camera to stabilize its vertical speed?
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i need your advice if someone experienced something similar. I try using digital servo but when i tried to connect it to board by this tutorial https://blogs.oracle.com/hinkmond/entry/connect_robot_servo_to_rpi3
servo motor only shakes for first ten cycles but after that turns normally. I have no idea why is that but in every article i read that controlling digital servo is same as analog with no need to program them after unboxing.
Thanks for any idea
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I am tasked with creating a system that will recognize fish pulled out of a lake. The system should be able to identify the type of species of fish. Typically, I turn to Arduino for projects like this. However, based on what I've read about image processing, it's sounding like Arduino doesn't have the processing power. Does anyone have any suggestions for development boards and cameras that can easily interface with the board?
I've look at this option, http://www.finboard.org/videos/introducing-finboard?utm_campaign=Embedded%20Processing%20and%20DSP%20Newsletter%2013-Q3%20NA&utm_medium=email&utm_source=Eloqua. It seems like it would be a nice all in one type of thing. Has anyone used anything like this?
Thanks!
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I'm kicking around the idea of building a small passive sonar for an autonomous submarine. I've looked through the net for parts and finding a good transducer for converting the sound underwater into an electrical impulse. After looking at parts I got into the piezoelectric materials used for doing this such as barium titanate or Lead zirconate titanate. From what I've read on the web, some of these materials are toxic.
My question is, are there piezoelectric materials that one could to build a sensor from scratch that does not possess the toxic qualities? Something that could preferably thrown in a pool w/ my kids and not give them or me any defects.
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Careful inspection of page 35 (figure 58) of the ADXL345 datasheet shows that under gravitational loading only, the chip uses a left-handed coordinate system. My own experiments with this chip confirm this.
I typically only use the chip to indicate the gravity vector. So when using this chip, I simply negate the values to get a right handed coordinate system. But this doesn't seem right. I assume there is a logical and mathematical explanation for the left-handed coordinate system but i can't figure out what it might be.
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I have a question about car-like robot localization using only dead-reckoning. Given:
robot position (at current time step) in the form $\begin{bmatrix}x & y & \theta\end{bmatrix}$ (theta is the heading)
steering angle
distance traveled between two time steps
How can I estimate the position of the robot at the next time step?
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I want to build some simple application. I need a 5 or 6 degrees of freedom robotic arm. The arm must have feedback, so that I can control it preciously. The arm must be able to handle at least 5 lbs. And the arm would be able to work 10 hours a day.
My budget is USD$300 . Any suggestion?
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I was looking into the Razor IMU from Sparkfun, and realized that the only example code on sparkfun's website was for it was meant for hooking it up to a computer (the AHRS head tracker used a serial to usb chip). I looked on google and saw nothing but stories about how it did not work.
Is there any good way to hook up the Razor IMU to an arduino uno (or any arduino without hardware support for more than one serial port), and if so does example code exist?
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I am a programmer by profession and new to Robotics. I have studied ECE, so know electronics, but not very familiar with mechanical aspects of robotics. I am working on a learning project with Dagu Rover 5 platform.
I am trying to control the 4 DC motors with PWM and want to use the optical encoders for feedback. I am looking for some algorithms, example code in C to effectively control the rover. I know how to control the GPIO, PWM and interrupts from the processor. I am more interested in learning the algorithm that controls the motors based on this. For now, i am working on a manual robot, controlled with up/down/left/right keys. In future, I would like to add sensors, camera etc and work on autonomous aspects. Any pointers would be helpful.
For reference, I am working on the Raspberry Pi platform to control the rover.
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Is it possible to get two images from the Raspberry Pi camera mounted on a remote controlled bot and have them sent to a computer through Wi-Fi and process the images in the computer to generate a depth map?
All this is to be done in a very short time so that the robot can be helped with its locomotion without making it completely autonomous.
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I am going to start a project on controlling robots using hand gestures.
Though I have used MATLAB for this purpose earlier, I realized it is extremely slow for any practical real-time system.
I am currently planning to use OpenCV for this purpose.
I want suggestions on, if OpenCV is the best alternative, are there any other alternatives and if I use OpenCV, which language should I go for, C, C++ or Python?
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I ask this since assembly language is really close to the micro-controller hardware, and what micro-controller would you reccomend.
The bot has to search for object that I show it before and then I 'lose' the object. Note, I do not know anything about micro-controllers.
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I'm interested in simulating Quadcopter control and Swarm co-ordinations. Was wondering if Blender or specifically MORSE was going to be good enough? According to the limitations of MORSE, it states:
MORSE was never meant to be a physically accurate simulator: while we rely on a state-of-the-art physics engine (Bullet), do not expect to accurately simulate robot arm dynamics or fine grasping. Other projects are doing that much better (like OpenGrasp for grasping).
While on-going efforts try to tackle this issue, we do not consider MORSE to have a good enough temporal accuracy and time synchronization capabilities for application like hybrid simulation (where some robots are simulated while others are physically operated).
Was wondering if anyone has experience in using blender for these types of applications.
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First, I'm a beginner in MCU/Robotic world (been working with ATMega+CVavr, but that's all). so please bear with me.
I'm making a prototype data glove (Like KeyGlove, but much more simpler), it consist of:
IMU sensors (MPU 9150 9DOF, all reading is fused with built in DMP) ->
Reads hand position and orientations
Minimum of 2 flex sensors -> Reads Figer flexion
MCU (well, Arduino to be specific)
The sensors are plugged in to the Arduino and the reading will be filtered (e.g Low pass, Kalmann) in the Arduino before being transferred over serial to PC. The PC will then translates the data into virtual gripper to move an object (VR)
Initially I planned to use UNO + Pansenti’s MPU9150 Library in my code, then I realised the flash memory size left would be so tiny (i.e MPU9150 lib code size is ~29k, Uno has 32k).
My project is still in very early stage, so a lot things are expected to be changed and added, with so little flash memory left. I can only do so much.
I immediately looking for Mega as replacement (256k flash) but I realised there is also newer Due with faster processor.
They cost effectively the same as for now.
.
My main concern here is the robustness and compatibility when:
Designing the HW interface to Arduino (making circuits, addding
shield)
Code development (available library)
Streaming and filtering the sensor readings (would 32 bit MCus helps, or it's overkill?)
I know this question might sound as too localized, but I believe a lot of projects that utilize multiple sensor reading + filtering similarly will also benefits from this discussion.
I'll revise the question if it's needed. The main question is probably
Would 32 bit MCUs perform significantly better in multiple sensor reading and signal filtering compared to 8 bit MCUs?
Or in my case.. should I go with Mega or Due?
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I'm looking to make an automatically shifting bicycle for my senior design project (along with some additional features TBD). However, I come from an electrical/software background; not a mechanical one. So I need to figure out a decent way to shift gears. I was thinking of leaving the gear system in place as is and using some sort of motor (servo or stepper motor with worm gears) to pull and release the wire cable as needed. However, I have some concerns with this; namely the amount of torque needed to pull the wire and finding something with enough holding torque. Perhaps my best option is to use the trigger shifters on as well and perhaps use a solenoid. My other concern (namely with the worm gear) is that it'll be too slow.
So I would like to pick your brains here for a moment. Thanks
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I'd like to assemble a prototype of brushless servo system using a RC brushless motor (heavily geared down), a sensored Electronic Speed Controller for RC motors, and a microcontroller to do the PID control.
I'd add three Hall sensors around the motor, and feed those signals into the ESC and the microcontroller. The MCU will run a PID controller, and output an RC servo compatible PWM signal to the ESC.
Question: Is this likely to work, or will I find that the ESC is trying to be clever? I have one RC car which only switches into reverse if you double pulse the reverse signal.
(Note, the reason I'm trying to get this working using an off-the-shelf ESC, rather than designing my own proper one is that development time is much more expensive than parts cost at the moment).
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So I'm doing some reading on Monte Carlo Localization, and it sounds like the approach is based on using a predefined map, but I just need to make sure (because I haven't read anywhere that it absolutely needs a predefined map). I just want to make 100% sure that my understanding is correct:
Does it absolutely need a predefined map?
[maybe I need to add the below stuff as another question, but here goes nothing]
And what other localization approaches are there that don't need a predefined map? So far I've only read about SLAM (which sounds to me like a general approach instead of a specific implementation).
Thanks in advance!
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I'm working on a robot with a team, and we're building our robot out of acetal polyoxymethylene (POM) (specifically, delrin) plastic. However, we'd like to prototype the robot before we build it out of POM, as POM is somewhat expensive.
There are several critical areas that plywood would be used in place of POM:
Over sliding surfaces
Around gearboxes
Under weight stress
We'd like to take into account the friction coefficients, smoothness, and rigidity of the materials in deciding whether plywood is a valid prototype substitute. The material will be 1/4" thick.
What differentiates plywood from acetal POM with respect to the relevant points?
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I am part of my college robotics team. We are participating in Robocon 2014 and are thinking about using mecanum wheels. We have done our research but one thing id like to clarify is: Does the number of rollers in the mecanum wheel effect its strafing? if yes then how?
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In earlier versions of the Arduino IDE there was a option to burn a the bootloader using an Arduino as the programmer. As of current there is only a burn bootloader option. Was the burn using a Arduino as a isp integrated into the still existing one, or did it disappear?
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Would like a product that enables me to use my computer to throw an small DC ON / OFF switch. Seems like a stupidly simple thing to do, but for the life of me I can't seem to find such a device when I search online.
Is there a device floating around out there that I can order? Or is there some kind of term I should be searching for?
Thanks so much!
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I just got my rover 5 chassis with 4 motors and 4 quadrature encoders and I am trying to utilize the optical encoders. I know the encoders generate pulse signals which can be used to measure speed and direction of the motor.
I want to know how 4 separate optical encoders add value for the controller of rover 5 like platform. The controller normally uses PWM to control the speed of the motor. If two motors are running at same speed then the encoder output will be same. So, why should the controller monitor all 4 encoders?
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I've been having trouble installing MORSE.
I am trying to install it on Ubuntu 12.04 and on a VirtualBox with Ubuntu 13.04 (I don't need it on a VirtualBox, I'm just trying to make something work).
On Ubuntu 12.04 I get the following errors at the cmake stage:
$ cmake -DCMAKE_INSTALL_PREFIX=/home/oferb/opt/morse_build ..
-- will install python files in /home/oferb/opt/morse_build/lib/python3/dist-packages
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
PYTHON_INCLUDE_DIR (ADVANCED)
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse/builder
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse/modifiers
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse/sensors
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse/multinode
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/src/morse/middleware
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/bindings
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/base
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/failures
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/robots/human
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/robots/segway
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/robots/pr2
used as include directory in directory /home/oferb/mnt/svr_home/opt/morse/testing/robots/pionner3dx
On a fresh VMBox with Ubuntu 13.04, after 'morse check' succeeds, I try "morse create mysim" and get:
adminuser@adminuser-VirtualBox:~$ morse create mysim
usage: morse [-h] [-b BASE] [--name NAME] [-c] [--reverse-color] [-g GEOM]
[-v]
{check,edit,run} [scene] ...
morse: error: argument mode: invalid choice: 'create' (choose from 'check', 'edit', 'run')
Any suggestions?
UPDATE:
I've managed to install MORSE on Ubuntu 12.04. Make sure your Blender was compiled with the same version of python (i.e python 3.2.2) that MORSE was compiled in. I used this Blender:
http://download.blender.org/release/Blender2.62
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I need to actuate 3 or 4 Cnc-like Nema 23 (~1N.m torque) stepper motors, I would like some cable solution to connect easily the motor to the motor driver.
I have not yet bought anything, I have searched various robotic stores and ebay, but did not yet found a triple (motor, cables, driver) which would be "plug and play".
As stepper motors usually have 4 to 6 cables, and there are multiple motors, manual soldering everything would be too time consuming, error prone and messy.
Is there a standard way to deal with cables for stepper motors ?
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I am in the FLL (First Lego League), and while we are waiting for the competitions, we want to work on a robot. Anyone have any ideas?
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I could use some guidance regarding a coordinate system transform problem. My situation is this: my system begins at some unknown location, which I initialize the location (x y) and orientation (roll, pitch, and yaw) all to zero. I establish a frame of reference at this point, which I call the "local" coordinate frame. It is fixed in the world and does not move. At system startup, the body frame is perfectly aligned with the local frame, where body +x points forward, +y to the right and +z down. The body frame is fixed to my system, and travels with the system as it moves.
I have an estimation routine that provides me with the x and y position, as well as the roll, pitch, and yaw of the system. Yaw is rotation about the z axis of the local frame. Pitch and roll are with respect to the body frame (I.e.,if the robot pitches up, I always get a positive value. If it rolls right, I get a positive value.)
How can I take the known roll and pitch values and transform them to be with respect to the local (fixed) frame?
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I found many tutorials and online calculators for the selection of dc motor to drive wheel, I understood how the torque affect the driving of wheel.
But what happen when I change the orientation of motor and load? What is the main criteria for a dc motor to work when I want to rotate a plate which is vertically mounted on motor's shaft, when the motor is placed vertically also (as shown in the picture)?
I am not an engineering student so please provide me an answer as simple as possible.
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I'm trying to learn about a very basic motor, the servo motor. Can these be found a thrift stores like Goodwill in old toys? Are these "robotic" quality? What toys or other kinds of things would I scavenge? All I want to do is get a motor. After that I want an Arduino and make it "work." Nothing complex.
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If I was controlling a normal brushed motor as a servo, I would measure the motor's position, and adjust the PWM signal to control the voltage. This way I could achieve a precise velocity/position profile if my control was good enough.
pwm_duty = CalcPID(motor_position - target_position);
When doing Field Oriented Control (FOC) of a brushless motor, there are two parameters I can control: The voltage angle, and the voltage magnitude. There are three things I can measure, the current angle and magnitude, and the rotor position.
I want to achieve a precise velocity/position profile including good control down to zero speed and reverse.
Question: how can I calculate the correct voltage field angle (or phase lead) and magnitude? Do I need two PID algorithms?
phase_lead = CalcPID_1( ... );
voltage_mag = CalcPID_2( ... );
Assume I can take any reasonable measurements of the motor state, including rotor position and winding current.
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I live in an apartment that has sliding windows in it. The apartment is naturally warm because we live above a mechanical room, such that we either opened the windows or ran the air conditioning through the winter. I want to create a device than can open and close the windows in the apartment depending on temperature. The software and electronics are already figured out, I just need to figure out how to move the windows.
This is a sample of the window. It takes about 4 lbs of force to pull it open, and they only open 6 inches(since I'm 16 stories high).
Ultimately, I want to make this cheap enough that I could replicate it on 6 windows.
My first thought was a linear actuator, but most of the ones I have seen are designed for moving 100+lbs and cost several hundred dollars. Pneumatic actuators are cheaper, but I'd have to run a network of air lines and solenoids, and would have a compressor that would randomly kick in. A double winch system would be very complicated to set up and prone to failure. Lastly, I was thinking of a cheap metal gear servo(dealextreme has 15kg/cm servos for under $15.00), but it would be somewhat difficult to use a series of turnbuckles and arms to translate into 6 inches of linear movement.
Any help would be appreciated.
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Has anybody experimented with GMAW for additive manufacturing? The thing is, welding wire is so much cheaper than ABS or PLA filaments and, well, it is steel you are printing in, not some flimsy plastic! I imagine the arc deposition printhead would be constructed similarly to one used in plastic filament printers, except there is no need for the heating element (so, even simpler). Welding often requires fast Z speed (to finely control the arc) so i think Delta (DeltaMaker) chassis would work best. GMAW calls for some sort of inert gas to insulate heated metal from oxygen. It would make sense to seal off most of the interior of the printer and fill it with heavier than air inert gas during printing.
I would highly appreciate any pointers on existing 3d printer designs employing this deposition method as well as flaws in design i outlined here.
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I have been researching on SLAM. I came across EKF SLAM which uses odometry to measure the robot's initial position in the map and as well as landmarks which helps the robot's position to be more accurate. Based on the SLAM for dummies, it has a problem of loop closure. In another journal, it was compared to fastSLAM and EKF has a big-O function of $O(K^2)$ where $K$ is the number of landmarks while fastSLAM has $O(M\log(K))$.
It was also said that the most promising SLAM algorithm from the journal "The vSLAM Algorithm for Navigation in Natural Environments"
is FastSLAM
However, the vSLAM used by an experiment done by the University of Pennsylvania is the occupancy grid SLAM.
I want to ask what would be the most approriate SLAM algorithm for vSLAM given an unmanned aerial vehicle like the quadrotor and RGB-D camera + IMU? Also are there any algorithm that can be extended to support co-operation?
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I have this project I'm working on where I'll need the speed of the stepper motor to change set speed at a certain distance, I just can't figure out a way to do it. I'm using arduino and a stepper motor, this is the current code.
#include <AccelStepper.h>
AccelStepper stepper1(AccelStepper::FULL4WIRE, 0, 1, 2, 3);
void setup()
{
stepper1.setMaxSpeed(200.0);
stepper1.setAcceleration(400.0);
stepper1.moveTo(5000);
}
void loop()
{
// Change direction at the limits
if (stepper1.distanceToGo() == 0)
stepper1.moveTo(-stepper1.currentPosition());
stepper1.run();
What I want it to do basically is to first moveTo(2500) at the current speed 200 then after 2500 I want it to increase speed to 400. After it has moved 5000 it turns and moves back to position but that's implemented already.
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In the book of SLAM for dummies, why do we even need the odometry when the robot would use the data retrieved from the laser scanner which is more accurate than odometry? Why not just rerly on the laser scanner and do away from the odometry? Is there any contribution by the odometry that the laser scanner does not have? Also, are all SLAM algorithms feature-based?
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The HC-SR04 is directly connected to an Arduino board with the receiver end(echo) connected to analog pin 2 and the transmitter (trigger) connected to digital pin 4.
I am wondering if I can use the sensor to sense the change in saturation from when object block its path. The receiver and transmitter will be positioned like this
The line in the middle is supposed to be a paper. I'll be using it to see the difference between one paper and two paper when they travel trough the two.
Now I'm not sure if this is possible but the way I see it working is kind of similar to an IR LED Arduino program connected to an LED, where when one paper passes trough the light gets a little bit weaker and with two it takes a heavier hit.
Is this possible?
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I am working on a 2D space where my robot needs to follow a trajectory while avoiding some obstacles.
I've read recently about methods for path planning as "Vector Field Histogram" and the "Dynamic window approach".
Is it worth to use these kind of algorithms for a 2D space or should I go with something as Potential Fields or Rapidly-Exploring Random Trees?
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I have read that you can wire a unipolar stepper to a bipolar driver, which I have, by ignoring the two extra wires. One concern I have is whether connecting a unipolar stepper to a bipolar driver will cause it to lose torque (holding or operating)?
Will it be the same? Increase?
I've read that bipolars are more bang for your buck energy-wise, and since you can "transform" a unipolar stepper to a bipolar good enough that the driver will still work right, I would think that it might run more efficiently. Is this true?
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I'm pretty new to the world of UAS after a ten year holiday from RC flying.
I'm looking at Ardupilot and am wondering what purpose telemetry serves? Is it just to get in flight data back to a ground station or can it also be used to program the system in flight? Are there other capabilities that I am missing?
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This question is to anyone familiar with object (specifically vehicle) detection research.
I'm new to computer vision and am confused about training object detection classifiers. Specifically, the objective is vehicle detection. I've been reading through vehicle detection literature for weeks now, but I'm still a bit confused.
What I'm confused about is evaluation. For the evaluation of a system, the research community usually has a benchmarked dataset which can be used for testing data. But the performance of a system also depends very much on the data that was used to train it, no?
So aren't there any training datasets out there, too? That would make for far more uniform method comparisons. I seem to keep finding papers using benchmarked datasets for evaluation, but making no mention of where they got their training data from.
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I want to steer a RC car in a straight line.The car has 4 sharp IR sensors on each corner of the car to help it steer the corridor.The corridor is irregular and looks something similar to the picture below.
The car needs to be stay exactly at the middle(shown by lighter line) and take help of the IR sensors to correct its path.
The car has a servo on the front wheel to steer and another that controls the speed.
I tried running it using a algorithm where it summed the values on each side of the car and took the difference.THe difference was then fed to a pid control the output of which went to steer the car.The greater the value from the pid (on either sides), the greater the value of the steering angle till it reaches the middle.
It works for the part where the walls are at similar distance from the center and even then it oscillates a lot around the center and fails miserably around the bumps in the corridor.
I need to make changes to the algorithm and need some help in steering me in the right direction.
The IR sensors are too finicky and is there a way to filter out the noise and make the readings more stable?
Any help regarding the changes that needs to be implemented is much appreciated.
Currently the car only uses 4 IR sensors to guide.I can also use 2 ultrasonic sensors.
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I belong to an AUV team at my university. We are planning to have a Multibeam 2D Imaging Sonar (the Blueview P900) for our AUV to detect obstacles underwater.
I have the following questions to ask on the feasibility of testing/implementing such sonars on AUVs.
As we know that these multibeam sonars have multiple reflections arriving at different times from various surfaces while testing in a pool, is there any recommended way to filter these noises in the image obtained from the sonar pings?
Are such sonars in use/test by any other team/organization anywhere else who do pool testing other than a ocean/reservoir testing where multiple reflections are almost zero except the reflections from the obstacle(s)?
Also i would like to know the recommended image processing algorithms that can be implemented/used to detect obstacles from the sonar images.
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Recently I am working with two accelerometers: BMA020 and BMA180. I will try to explain my problem using BMA020 as example because it is less accurate therefore problem is more visible. When I hold my Acc in neutral position I get correct average result: -1G. Now I turn my Acc upside down but this time my average result is +0,91G. The same problem occurs for other axis. For BMA180 problem is less visible (-1G in normal position and +0.98G upside down). Do you know why accelerometer behaves like this ?
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I've been able to use pymavlink.mavutil to read telemetry from a .tlog created by MissionPlanner.
To do this, I create a mavlogfile like this:
mlog = mavutil.mavlink_connection('mylogfile.tlog')
Now I want to read the flight parameters (settings) from the .tlog . The method mavlogfile.param_fetch_all() appears to be designed only to work with a live telemetry link rather than a log. It sends a parameter request command, which obviously has no result when you are linked to a log rather than an actual aircraft.
I know the parameters are in the .tlog... how do I get them out?
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I need to track a point in space. The point is less than 2 m away, it has to be passive, no batteries, and no charging.
I don't always have a line of sight. I need to pinpoint it to about a centimeter. I need to sample it at a frequency of 10 Hz or more.
Can it be done at all? Does such a solution exist?
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I'm a first year electronics engineering student. I love almost all the aspects of robotics - the electronics, algorithms, control theory etc. I can't stand the mechanical aspect of robotics though.
Can I have a fulfilling career in Robotics if I hate mechanics but love all other parts of robotics? I'm ready to learn mechanics if I absolutely have to, but would strongly prefer not to learn any more than the absolute basics.
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First, is it possible to build map without landmarks for a robot in 2D? Let's say we have an aisle surrounded by two walls. The robot moves in this environment. Now is it feasible to build such a SLAM problem? Or landmarks must be available to do so?
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I'm looking to build an outdoor robot and I need to know if time-of-flight cameras like the SwissRanger™ SR4500 work in fog, does anybody have some experiences on that?
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The state vector is
$$ \textbf{X} = \begin{bmatrix} x \\ y \\ v_{x} \\ v_{y} \end{bmatrix}$$
transition function is
$$
\textbf{X}_{k} = f(\textbf{X}_{k-1}, \Delta t) =
\begin{cases}
x_{k-1} + v_{xk} \Delta t \\
y_{k-1} + v_{yk} \Delta t
\end{cases}
$$
$z_{b} = atan2(y, x)$ and
$z_{r} = \sqrt{ x^{2} + y^{2}}$
the Jacobian of the observation model:
$$
\frac{\partial h}{\partial x} =
\begin{bmatrix} \frac{-y}{x^{2}+y^{2}} & \frac{1}{x(1+(\frac{y}{x})^{2})} & 0 & 0 \\
\frac{x}{\sqrt{ x^{2} + y^{2}}} & \frac{y}{\sqrt{ x^{2} + y^{2}}} & 0 & 0
\end{bmatrix}
$$
My question is how the Jacobian of the observation model has been obtained? and why it is 2X4?
the model from Kalman filter.
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I lead a university robotics team that needs PID controllers for four drive motors and two additional motors that are used in a secondary system. I would strongly prefer to buy pre-built PID controllers that provide just about any reasonable interface for setting PID constants, motor velocity and direction, as the controllers are not remotely central to the difficult, interesting problems we're trying to solve. To my astonishment, the Internet doesn't seem to be saturated with such controllers (talk about reinventing the wheel - hundreds of tutorials but almost no pre-built solutions! Did Willow Garage build their own PID controller for the PR2?!).
Does anyone have recommendations/experience, preferably pointers to such controllers?
I've Googled around quite a bit, and so far this is the best option I've found. It's a cape for a BeagleBone Black (which is the board we're using). The problem is that the Python library is not finished - it resets PID constants at every call, it doesn't support changing the direction of the motor, and it seems to only support setting motor power, not velocity, which gives me the impression that it's not actually using the PID controller at all.
Additional details:
The stall current of our drive motors is 6A. They are brushless DC motors with quadrature encoders. The secondary motors are much smaller, and we're building our own encoders for them.
Our code base is in Python, and we're running on a BeagleBone Black using the latest Debian image from Robert Nelson (that guy's awesome!). Our batteries provide 14.8V, and we already have 3.3V and 5V rails.
Our robot is fairly small, about 1x1x2 feet, and weighs about 9 pounds. This info is meant to give perspective with regard to scale.
$350 or so is the comfortable top range of what we could spend to get all 6 motors PID-controlled.
Any help would be greatly appreciated!
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For a 6DoF robot with all revolute joints the Jacobian is given by:
$$
\mathbf{J} =
\begin{bmatrix}
\hat{z_0} \times (\vec{o_6}-\vec{o_0}) & \ldots & \hat{z_5} \times (\vec{o_6}-\vec{o_5})\\
\hat{z_0} & \ldots & \hat{z_5}
\end{bmatrix}
$$
where $z_i$ is the unit z axis of joint $i+1$(using DH params), $o_i$ is the origin of the coordinate frame connected to joint $i+1$, and $o_6$ is the origin of the end effector. The jacobian matrix is the relationship between the Cartesian velocity vector and the joint velocity vector:
$$
\dot{\mathbf{X}}=
\begin{bmatrix}
\dot{x}\\
\dot{y}\\
\dot{z}\\
\dot{r_x}\\
\dot{r_y}\\
\dot{r_z}
\end{bmatrix}
=
\mathbf{J}
\begin{bmatrix}
\dot{\theta_1}\\
\dot{\theta_2}\\
\dot{\theta_3}\\
\dot{\theta_4}\\
\dot{\theta_5}\\
\dot{\theta_6}\\
\end{bmatrix}
=
\mathbf{J}\dot{\mathbf{\Theta}}
$$
Here is a singularity position of a Staubli TX90XL 6DoF robot:
$$
\mathbf{J} =
\begin{bmatrix}
-50 & -425 & -750 & 0 & -100 & 0\\
612.92 & 0 & 0 & 0 & 0 & 0\\
0 & -562.92 & 0 & 0 & 0 & 0\\
0 & 0 & 0 & 0 & 0 & 0\\
0 & 1 & 1 & 0 & 1 & 0\\
1 & 0 & 0 & -1 & 0 & -1
\end{bmatrix}
$$
You can easily see that the 4th row corresponding to $\dot{r_x}$ is all zeros, which is exactly the lost degree of freedom in this position.
However, other cases are not so straightforward.
$$
\mathbf{J} =
\begin{bmatrix}
-50 & -324.52 & -649.52 & 0 & -86.603 & 0\\
987.92 & 0 & 0 & 0 & 0 & 0\\
0 & -937.92 & -375 & 0 & -50 & 0\\
0 & 0 & 0 & 0.5 & 0 & 0.5\\
0 & 1 & 1 & 0 & 1 & 0\\
1 & 0 & 0 & -0.866 & 0 & -0.866
\end{bmatrix}
$$
Here you can clearly see that joint 4 and joint 6 are aligned because the 4th and 6th columns are the same. But it's not clear which Cartesian degree of freedom is lost (it should be a rotation about the end effector's x axis in red).
Even less straightforward are singularities at workspace limits.
$$
\mathbf{J} =
\begin{bmatrix}
-50 & 650 & 325 & 0 & 0 & 0\\
1275.8 & 0 & 0 & 50 & 0 & 0\\
0 & -1225.8 & -662.92 & 0 & -100 & 0\\
0 & 0 & 0 & 0.86603 & 0 & 1\\
0 & 1 & 1 & 0 & 1 & 0\\
1 & 0 & 0 & 0.5 & 0 & 0
\end{bmatrix}
$$
In this case, the robot is able to rotate $\dot{-r_y}$ but not $\dot{+r_y}$. There are no rows full of zeros, or equal columns, or any clear linearly dependent columns/rows.
Is there a way to determine which degrees of freedom are lost by looking at the jacobian?
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I have an unscented Kalman filter (UKF) that tracks the state of a robot. The state vector has 12 variables. Each time I carry out a prediction step, my transfer function (naturally) acts on the entire state. However, my sensors provide measurements of different parts of the robot's state, so I may get roll, pitch, yaw and their respective velocities in one measurement, and then linear velocity in another.
My approach to handling this so far has been to simply create sub-matrices for the covariance, carry out my standard UKF update equations, and then stick the resulting values back into the full covariance matrix. However, after a few updates, the UKF yells at me for trying to pass a matrix that isn't positive-definite into a Cholesky Decomposition function. Clearly the covariance is losing its positive-definite properties, and I'm guessing it has to do with my attempts to update subsets of the full covariance matrix.
As an example taken from an actual log file, the following matrix (after the UKF prediction step) is positive-definite:
1.1969 0 0 0 0 0 0.11567 0 0 0 0 0
0 1.9682 0 0 0 0 0 0.98395 0 0 0 0
0 0 1.9682 0 0 0 0 0 0.98395 0 0 0
0 0 0 1.9682 0 0 0 0 0 0.98395 0 0
0 0 0 0 1.9682 0 0 0 0 0 0.98395 0
0 0 0 0 0 1.9682 0 0 0 0 0 0.98395
0.11567 0 0 0 0 0 0.01468 0 0 0 0 0
0 0.98395 0 0 0 0 0 1 0 0 0 0
0 0 0.98395 0 0 0 0 0 1 0 0 0
0 0 0 0.98395 0 0 0 0 0 1 0 0
0 0 0 0 0.98395 0 0 0 0 0 1 0
0 0 0 0 0 0.98395 0 0 0 0 0 1
However, after processing the correction for one variable (in this case, linear X velocity), the matrix becomes:
1.1969 0 0 0 0 0 0.11567 0 0 0 0 0
0 1.9682 0 0 0 0 0 0.98395 0 0 0 0
0 0 1.9682 0 0 0 0 0 0.98395 0 0 0
0 0 0 1.9682 0 0 0 0 0 0.98395 0 0
0 0 0 0 1.9682 0 0 0 0 0 0.98395 0
0 0 0 0 0 1.9682 0 0 0 0 0 0.98395
0.11567 0 0 0 0 0 0.01 0 0 0 0 0
0 0.98395 0 0 0 0 0 1 0 0 0 0
0 0 0.98395 0 0 0 0 0 1 0 0 0
0 0 0 0.98395 0 0 0 0 0 1 0 0
0 0 0 0 0.98395 0 0 0 0 0 1 0
0 0 0 0 0 0.98395 0 0 0 0 0 1
The difference between the two matrices above is
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 -0.00468 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0
As you can see, the only difference between the two is the value in the location of the variance of linear X velocity, which is the measurement I just processed. This difference is enough to "break" my covariance matrix.
I have two questions:
Updating a subset of the filter doesn't appear to be the right way to go about things. Is there a better solution?
Alternatively, am I missing a step that would keep my covariance matrix as positive-definite?
Thanks!
EDIT:
It looks like I'm not properly placing the values back into the original covariance matrix. Simply copying the values back isn't sufficient. I need to track the correlation coefficients for the covariance matrix, and make sure that when I update a variance value, I update all the values in its row/column to maintain the correlation coefficient value. I have to do some more testing to verify that this is my issue, but some initial analysis in Matlab suggests that it is. If I'm correct, I'll answer my own question.
EDIT 2:
Given the response below and after trying it, I can see that my original edit idea won't fly. However, I have one more question:
As this is a UKF, I don't actually have Jacobian matrices. I think I see how I would make it work within the UKF update equations, but even in an EKF - and I ask because I have one of those as well - my state-to-measurement function $h$ is going to end up being the identity matrix, as I am directly measuring my state variables. In the case, I take it my "Jacobian" would just be an $m \times n$ matrix with ones in the $(i, i)$ location, where $i$ is the index of the measured values in the measurement vector?
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This is a follow up to
Maintaining positive-definite property for covariance in an unscented Kalman filter update
...but it's deserving of its own question, I think.
I am processing measurements in my EKF for a subset of the variables in my state. My state vector is of cardinality 12. I am directly measuring my state variables, which means my state-to-measurement function $h$ is the identity. I am trying to update the first two variables in my state vector, which are the x and y position of my robot. My Kalman update matrices currently look like this:
State $x$ (just test values):
$$
\left(\begin{array}{ccc}
0.4018 & 0.0760
\end{array} \right)
$$
Covariance matrix $P$ (pulled from log file):
$$
\left(\begin{array}{ccc}
0.1015 & -0.0137 & -0.2900 & 0 & 0 & 0 & 0.0195 & 0.0233 & 0.1004 & 0 & 0 & 0 \\
-0.0137 & 0.5825 & -0.0107 & 0 & 0 & 0 & 0.0002 & -0.7626 & -0.0165 & 0 & 0 & 0 \\
-0.2900 & -0.0107 & 9.6257 & 0 & 0 & 0 & 0.0015 & 0.0778 & -2.9359 & 0 & 0 & 0 \\
0 & 0 & 0 & 0.0100 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & 0.0100 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & 0.0100 & 0 & 0 & 0 & 0 & 0 & 0 \\
0.0195 & 0.0002 & 0.0015 & 0 & 0 & 0 & 0.0100 & 0 & 0 & 0 & 0 & 0 \\
0.0233 & -0.7626 & 0.0778 & 0 & 0 & 0 & 0 & 1.0000 & 0 & 0 & 0 & 0 \\
0.1004 & -0.0165 & -2.9359 & 0 & 0 & 0 & 0 & 0 & 1.0000 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0.0100 & 0 & 0 \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0.0100 & 0 \\
0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0.0100 \\
\end{array} \right)
$$
Measurement $z$ (just test values):
$$
\left(\begin{array}{ccc}
2 & 2
\end{array} \right)
$$
"Jacobean" $J$:
$$
\left(\begin{array}{ccc}
1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 & 0 \\
\end{array} \right) $$
Measurement covariance $R$ (just test values):
$$
\left(\begin{array}{ccc}
5 & 0 \\
0 & 5 \\
\end{array} \right) $$
Kalman gain $K = PJ^T(JPJ^T + R)^{-1}$:
$$
\left(\begin{array}{ccc}
0.0199 & -0.0024 \\
-0.0024 & 0.1043 \\
-0.0569 & -0.0021 \\
0 & 0 \\
0 & 0 \\
0 & 0 \\
0.0038 & 0.0000 \\
0.0042 & -0.1366 \\
0.0197 & -0.0029 \\
0 & 0 \\
0 & 0 \\
0 & 0 \\
\end{array} \right) $$
$K$ is 12x2, meaning that my innovation - and therefore both measurement and current state - would need to be 2x1 in order to have a 12x1 result to add to the current full state:
$x' = x + K(z - h(x_s))$
where $x_s$ is a vector containing only the parts of the full state vector that I am measuring.
Here's my question: $K(z - h(x_s))$ yields
$$
\left(\begin{array}{ccc}
0.0272 \\
0.1969 \\
-0.0948 \\
0 \\
0 \\
0 \\
0.0062 \\
-0.2561 \\
0.0258 \\
0 \\
0 \\
0 \\
\end{array} \right) $$
Does it make sense that this vector, which I will add to the current state, has non-zero values in positions other that 1 and 2 (the x and y positions of my robot)? The other non-zero locations correspond to the robot's z location, and the x, y, and z velocities. It seems strange to me that a measurement of x and y should yield changes to other variables in the state vector. Am I incorrect in this assumption?
Incidentally, the covariance update works very well with the Jacobean in this form, and maintains its positive-definite property.
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I am trying to control the Rover 5 robot using an Android app with a touch-based joystick control in the app UI. I want to calculate the speed of the left and right motors in the rover when joystick is moved.
From the joystick, I get two values, pan and tilt. I convert them into the polar coordinate system with r and theta. Where r ranges from 0 to 100 and theta from 0 to 360. I want to derive an equation which can convert the (r, theta) to (left_speed, right_speed) for rover. The speed values also are in the [0;100] range.
Now, here is what I have figured out till now. For any value of r,
If theta = 0 then left_speed = r, right_speed = -r (turning right on spot)
If theta = 90 then left_speed = r, right_speed = r (moving forward at speed r)
If theta = 180 then left_speed = -r, right_speed = r (turning left on spot)
If theta = 270 then left_speed = -r, right_speed = -r (moving backwards at speed r)
For other values, I want it moving and turning simultaneously. For example,
If theta = 45 then left_speed = alpha*r, right_speed = beta*r (moving forward while turning right)
So, basically for any (r, theta), I can set speeds as,
(left_speed, right_speed) = (alpha*r, beta*r)
I need to formulate an equation where I can generalize all these cases by finding alpha and beta based on theta.
How can I do this? Is there is any existing work I can refer to?
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I am new in robotics. May be this question looks like too naive but i want to know which is a better board among Arduino Uno R3 or Roboduino ATMega168 or Arduino Mega 2560 R3 for my purpose mention below -
A simple robot with wheels, can move around.
Can have IR sensors and camera.
Is powerful enough to deal with computer vision computations.
Arduino Mega 2560 R3 looks more powerful than the other too, I just want to know if my purpose can be solved with other two boards too?
Thanks
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I'm using the telemetry kit from 3DR robotics (433MHz) to interface with Ardupilot Mega 2.6, controlling a quadcopter. The Mission Planner (v1.2.84) by Michael Oborne works well with the telemetry kit, transmitting flight data (IMU, compass, GPS etc.) from the quadcopter to the GCS and displaying them in their GUI.
However, I would like to see the same data in the hyperterminal (windows system). The radio receiver on the GCS connects to my PC through a USB drive. I have tried calling the remote radio station using all possible Baud rates, starting from 110 to 921600 (including 57600). I've set the data bits to 8 and stop bits to 1. 'None' for parity and flow control.
However, all that I ever get on my terminal is either gibberish or no data at all. I also tried burning this software to the radio receiver and tried using AT commands on the radio.
It connects OK with '+++', but keeps returning error for AT1, ATT etc.
Please give me an idea about how to get flight data at the hyperterminal.
Thanks.
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This is my first question on this site, might be a little subjective :)
There is an ongoing process of many cool cyclonic changes of technology in the electronics and software industry.
Concurrency and Parallelism
What will be the implications of GPGPU, Multi-core and "programming in the large" model in the specific case of embedded software, and how will it influence the styles and conventions in the community?
Single board multicore hardware like soon to be released Parallela can be an example?
Programming language research
The results have been excellent. Functional Programming has supposedly started reaching the masses. It was late night previous weekend when I briefly skimmed through an example of functional reactive programming to solve real time problems. AI people are also suggesting that we should be programming our robots in Declarative Domain Specific languages soon. It would be nice to know the implications on the robotics community.
There has been a tremendous growth of frameworks like ROS and Urbi too!! That should be the region to look upon..
Most of the robotics, embedded and high performance AI codebase directly depends on C/C++ , and though languages like Rust and D are bubbling up, wouldn't it take massive amount of time to adopt the new languages, if ever adaptation begins?
AI
Correct me, but it seems like a lot of time has passed and there are not many major production results from the AI community. I've heard about cognitive architectures of old like ACT-R and 4CAPS. They seem to be in hibernation mode!
There seems to be a lot of work lately on otherwise intelligent systems (solved problems) like Computer vision and Data mining, but these problems cater to supercomputing and industrial crowd more. Could there be any possible shift towards low powered systems soon?
Thanks
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I have an old beat-up netbook that is currently collecting dust. I've also only taken stuff apart, without having to worry about putting it back together, so please bear with my possibly stupid questions.
a) I imagine it's possible to wire this baby up to servos, breadboards, and all that good stuff. Am I correct?
b) I'd like to start with some simple Raspberry Pi-like projects (think automating my irrigation system, feeding the dog from work, etc). Obviously barring the energy expenditure, wouldn't a netbook be more apt than a Raspberry Pi for handling this type of thing?
c) I have basic Python experience, but I wouldn't mind picking up more as I go. Would that be sufficient?
Cheers!
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I'm reading amcl document on ROS Wiki. In its subscribed topics there is not odometry topic, why? It works only with laser?
Subscribed Topics: (From ROS Wiki)
scan (sensor_msgs/LaserScan)
tf (tf/tfMessage)
initialpose (geometry_msgs/PoseWithCovarianceStamped)
map (nav_msgs/OccupancyGrid)
And my next question is how can I use amcl in Gazebo simulator for turtlebot? Any tutorial available?
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I've got a code where I have a motor running back and forth and buttons connected to a scanner, when I press the buttons it causes the motor to stop and over rides it. I would like them to run parallel to each other so the codes don't interrupt each other.
Here is my code
#include <AccelStepper.h>
// Define some steppers and the pins they will use
AccelStepper stepper1(AccelStepper::FULL2WIRE, 2, 3);
const int buttonPin = 4;
const int button2Pin = 14;
const int pulseopto1 = 9;
const int startScan = 11;
int buttonState = 0;
long previousMillis = 0;
long interval = 5;
void setup()
{
pinMode(buttonPin, INPUT);
pinMode(button2Pin, INPUT);
pinMode(pulseopto1, OUTPUT);
pinMode(startScan, OUTPUT);
stepper1.setMaxSpeed(40000.0);
stepper1.setAcceleration(100000.0);
stepper1.moveTo(25000);
}
void loop()
{
buttonState = digitalRead(buttonPin);
if (buttonState == LOW)
{
digitalWrite(startScan, HIGH);
}
else (buttonState == HIGH);
{
digitalWrite(startScan, LOW);
}
{
buttonState = digitalRead(button2Pin);
if (buttonState == LOW)
{
// turn LED on:
digitalWrite(pulseopto1, HIGH);
delay(5);
digitalWrite(pulseopto1, LOW);
delay(5);
}
else
{
// turn LED off:
digitalWrite(pulseopto1, LOW);
}
}
// Change direction at the limits
if (stepper1.distanceToGo() == 0)
{
stepper1.moveTo(-stepper1.currentPosition());
}
stepper1.run();
}
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In ROS I've recorded a bag file from a custom robot (in real world) that does not provide covariance matrix and I want to use /odom to feed an EKF, but covariance matrix is 0. How can I calculate it?
Note:
Covariance matrix is needed by EKF to estimate position.
It's a sample of /odom:
pose:
pose:
position:
x: 0.082
y: 0.507
z: 0.0
orientation:
x: 0.0
y: 0.0
z: -0.789272088731
w: 0.614043622188
covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
twist:
twist:
linear:
x: 0.104
y: 0.0
z: 0.0
angular:
x: 0.0
y: 0.0
z: 0.0663225115758
covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
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From the designs usually shown of rocker bogie systems, the whole weight of platform seems to be supported by only one rod, be it differential bar or gear. Isn't this a bit unstable system because if we have arms of rover at one end we will have a high torque about that rod?
Is my understanding such rocker bogie systems correct? If so, are there any solutions to this problem which don't sacrificing the functionality of rover?
To clarify, I want to know how rovers like curiosity are designed so as to balance such a heavy platform with a differential bar mechanism. I am trying to make a small rocker bogie myself and I want to avoid this anticipated problem.
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It would be incredibly useful if I could print my own gearing solutions, even if I have to print the gears one at a time. However, I do not know how the market's cheapest printers will accommodate this task.
--The gears need be 2-3 inches in diameter, and they will bear only a very light load (much less than 1 foot pound), so the material need not be strong or machinable.
--The tolerances need only be sufficient for the teeth to mate robustly, preventing any hang. Unfortunately, I do not have a sense of what tolerances will allow gears to mate properly.
--(If the machine is precise enough to print a hole to statically mate with a shaft of a specified dimensions due to friction, excellent. If not, I can probably improvise a tiny shaft hole with adhesive.)
--Because this may be used in close proximity to pavement, a melting temperature in excess of 100F is desirable but not required.
--Because any given element will interact kinetically only with other elements that have also been 3D printed (except a metallic shaft), compatibility with external resources is not required.
I would be grateful to anyone who could shed some light on this issue!
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I'm dealing with a board that no matter what I do I can't seem to make CAN work over 125 kbit/s. I'll give some detail about the board on the bottom, but I'm going to keep this question generic.
First of all, regarding hardware. From what I've gathered, there isn't any need for a pull-up resistor on the TX of CAN. Is that correct? It may perhaps be chip-specific, but wherever I see, it seems that the TX/RX lines are directly connected to the transceiver.
Second, regarding bit-timing: Using different calculators, for example, Kvaser or the one from Microchip, I can see the following configuration (for 64 kHz input clock):
SYNC PROP PHASE1 PHASE2 BRP (prescaler)
125 kbit/s 1 1 3 3 32
250 kbit/s 1 1 3 3 16
500 kbit/s 1 1 3 3 8
1000 kbit/s 1 1 3 3 4
I've seen this from more than one source. Furthermore, the numbers fit to the formula in the datasheet of the microcontroller.
However, only the configuration for 125 kbit/s works for me. I'm using CANreal to monitor the messages.
I've tried different configurations for the CAN, for example with 16 time quanta instead of 8 as well as changing my microcontroller's clock to 16 MHz and using again different values. Regardless of all that, speeds higher than 125 kbit/s result in only errors and warnings in CANreal (which are taken from the CAN driver). Note that the same CAN board, driver and software works with 1 Mbit/s with some other hardware I have.
This all is made harder since, as soon as I put a probe from my oscillator on the TX line, it becomes a continuous 0-1 alteration like the following:
__------ __------ __------ __------ __------
/ | / | / | / | / |
/ | / | / | / | / |
/ | / | / | / | / |
| | | | | | | | | |
| |_| |_| |_| |_| |
Which is not something I would be outputting by software. In fact, as soon as I remove the probe, the messages start arriving (again, only at 125 Mbit/s). So basically, I don't seem to be able to have any oscillator debugging available.
Back to my "first of all, regarding hardware", the shape of the signal suggests a pull-up resistor may be necessary, but I haven't seen the need for that in any datasheet I found. Furthermore, my microcontroller configures the pin when used as CAN, so I don't have control over making it push-pull (since it looks like it's open-drain). Not to mention the microcontroller doesn't even have a configuration to make the pin push-pull.
Is there any hidden parameter somewhere that should also be set? Is a pull-up resistor necessary after all? Why would the oscillator probe cause such a behavior?
Details from the board:
MCU: P18F45K80. CAN is connected to its default RB2 and RB3.
CAN transceiver: ISO1050
Compiler: mikroC
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i want to model the quadrotor using experimental method "i have not built it yet" what i want to do is: turn only one motor at a specific speed ,then plot the x,y,z and the angles then identify the transfert functions from the plots,x/w1,y/w1,... and so on, but i don't know if it's possible or what graphs i will have,so if you know about the subject or maybe tried something like that, and feel free to add anything you think might be helpfull
|
I am building a machine and need 2 Stepper Motor for that.
The motors are driven using by a 3.3v arm device.
I have made the following selections regarding the stepper motor, stepper motor driver and the power supply.
Power Supply 12 Volt Power Supply - 3.5 Amp Single Output
Stepper Motors Stepper Motor: Unipolar/Bipolar, 200 Steps/Rev, 42×48mm, 4V, 1.2 A/Phase
Stepper Motor Driver DRV8825 Stepper Motor Driver Carrier, High Current
I tried my best to research the compatibility and came up with these.
Is this a good selection considering the fact that the Power Supply will be driving 2 of these motors.
I will be running the motors at 1/16 step for high resolution.As far as the speed is concerned,it's going to be pretty slow but they will be running continuously for hours in end.Basically what I am trying to do here is make a V-Plotter.As far I can tell, there will be loads of start stop motion in the motors though.
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I'm interested in getting a Create for a project I'll be working on, and wanted some information about it from somebody that already has one:
How much weight can it safely carry? I talked with Irobot's tech support and they told me the maximum is 5lb, but searching on the internet it seems like this limit is actually not as strict as it appears to be. I'm asking because I'd need to put a 3kg laptop on top of it, which would mean ~3.5-4kg if you also consider the kinect and eventual supports for both. I guess I could use a netbook and send the data I need to another computer, but I wanted to avoid the additional overhead of the wireless link.
For how long does it run using AA batteries? I'm inclined on not getting the battery pack, since I'd be using the robot in europe, so I'd also need a transformer if I went with the battery pack option.
Thanks!
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I am trying to get precise control over the speed of rover 5 based robot. It has four PWM controlled motors and 4 Optical Quadrature Encoders. I am using 4-channel motor controller with rover 5 chassis. I am using arduino Nano for control. I am able to read encoder INT output and change PWM based on pulse width to control speed. But, as a result, I am getting heavy oscillations in the control output. That makes, the robot to move in steps, as PWM is changing constantly. I need an algorithm which can minimize this ringing and have a smooth moving robot. Here is my arduino code snippet.
void setup() {
Serial.begin(9600);
init_motors();
init_encoders();
req_speed[0] = 20;
req_speed[1] = 20;
req_speed[2] = 20;
req_speed[3] = 20;
}
void loop() {
update_encoders();
update_motors();
}
void update_motors() {
int i, err;
unsigned long req_width;
if(micros() - mtime > 2999) {
mtime = micros();
for(i=0; i<4; i++) {
digitalWrite(pins_dir[i], req_speed[i]>0);
if(mtime - change_time[i] > 50000ul && req_speed[i] != 0) {
cur_pwm[i] += 5;
}
if(req_speed[i] > 0)
cur_err[i] = req_speed[i]*10 - cur_speed[i];
else
cur_err[i] = (-req_speed[i]*10) - cur_speed[i];
if(cur_err[i] > 0 && cur_pwm[i] < 255) {
cur_pwm[i]++;
} else if(cur_err[i] < 0 && cur_pwm[i] > 0) {
cur_pwm[i]--;
}
analogWrite(pins_pwm[i], cur_pwm[i]);
}
}
}
void update_encoders() {
int i;
unsigned long w;
enc_new = PINC & B00001111;
unsigned long etime = micros();
for (i=0; i<4; i++) {
if((enc_old & (1 << i)) < (enc_new & (1 << i)))
{
w = (unsigned long)(((etime - change_time[i])));
pulse_width[i] = (w + pulse_width_h1[i] + pulse_width_h2[i])/3;
pulse_width_h2[i] = pulse_width_h1[i];
pulse_width_h1[i] = pulse_width[i];
change_time[i]=etime;
pulse_count[i]++;
cur_speed[i] = (3200000ul / pulse_width[i]);
}
}
enc_old=enc_new;
}
Here req_speed is between -100 to 100, where sign indicates direction. Please consider all undefined variables as globals. I experimentally measured that, when motor is running at full speed, the pulse width is around 3200us.
Encoders' INT outputs (XOR of A and B) are connected to A0 thru A3. Motor PWM is connected to D3, D5, D6, D9. Please let me suggest any improvements to this code and advice me about what am I missing here.
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I have a chip that is labeled L293D with a small 'ST' logo, which does not behave like I believe a L239D should:
I have the chip on a breadboard with pins 4,5,12 and 13 connected to the ground rail. The positive rail gets 6V from a battery pack.
A motor is connected to pins 3 and 6.
Pin 2 is connected to the positive rail.
Now, when I connect pin 1 (enable 1) to the positive rail, the motor spins, which is expected.
The weird thing is that if I connect pin 16 instead of pin 1 to positive, the motor spins, as well.
Also, with the motor connected to 11 and 14, and 15 connected to positive, the motor spins if I connect pin 1 or pin 16 to positive, but not if I connect pin 9 (which should be the enable pin for that side).
Does any of that make sense? Am I missing something here?
Thanks!
|
I am working right now with Arduino UNO and HC-05 bluetooth module.I followed the instruction given on this link for wiring. So there are 2 mode of working with this HC-05 module
Simple serial communication
Working in AT command mode so as to change the parameters of HC-05 module
As long as I work in simple serial communication mode, everything works fine but when I tried to change the parameters of module, it didn't work out. For working in At command mode, PIN NO 34 of HC-05 module needs to be high which I had taken care of. Lately I found that in mu module they had knowingly not connected the Berg strip to PIN 34, so I connected the PIN directly, even though I am not able to change the parameters of module and when I write any command on COM port of arduino IDE, I get this response
Enter AT commands:
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
ERROR:(0)
ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿõÿýì¢^
I think that garbage is due to my code
Here is my code:
#include <SoftwareSerial.h>
SoftwareSerial BTSerial(10, 11); // RX | TX
void setup()
{
pinMode(9, OUTPUT);
digitalWrite(9, HIGH);
Serial.begin(9600);
Serial.println("Enter AT commands:");
BTSerial.begin(38400);
}
void loop()
{
uint8_t x;
char CommandFromSerial[50]=" ";
char ResponseFromBluetooth[50]= " ";
if ((Serial.available())){
if(Serial.available()>0){
for(x=0;x<50;x++)
CommandFromSerial[x]=Serial.read();
BTSerial.println(CommandFromSerial);
}
}
if ((BTSerial.available())){
if(BTSerial.available()>0)
for(x=0;x<50;x++)
ResponseFromBluetooth[x]=BTSerial.read();
Serial.println(ResponseFromBluetooth);
}
}
I am not able to figure out what I am doing wrong. I used this command on COM port
AT\r\n and many other commands but every time I get the same response.
Did I mess up with my bluetooth module unknowingly?
|
I'm working on a legged robot and generating joint torques. Basically the robot seems to be statically stable to some extend. The robot goes instable if the center of pressure moves to the border of the feet. I'm looking for some method to move away the center of pressure from the feet edges after having calculated my joint torques. In Sentis thesis ( http://ai.stanford.edu/~lsentis/files/Thesis-Sentis-2007.pdf ) , it is mentioned that he somehow manages to cancel out the internal forces to keep the feet flat against the supporting surfaces.
Does anyone has got experience in dealing with internal forces? As far as I understood the literature one can modify the nullspace of the calculated torques to achieve that the COP remains in the geometrical center of the considered foot. I'm looking for methods apart from the virtual linkage model as it did not seem to work for me or someone with whom I could discuss the virtual linkage model described in ( http://ai.stanford.edu/~lsentis/files/tro-2010.pdf ) as I might not have it understood it correctly.
|
I am trying to use a push button in order to know and print number of time a push button is pressed using a counter.But everytime i press the button , counter get incremented to sometime 3 and sometime 5 and some time counter does start >100 and continue.
I had preferred the this link for wiring PUSH button with arduino.
and here is my code
const int buttonPin = 2; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin
// variables will change:
int buttonState = 0; // variable for reading the pushbutton status
int count = 0;
void setup() {
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
// initialize the pushbutton pin as an input:
pinMode(buttonPin, INPUT);
pinMode(buttonPin, INPUT);
Serial.begin(9600);
buttonState = digitalRead(buttonPin);
digitalWrite(ledPin,LOW);
}
void loop(){
// read the state of the pushbutton value:
buttonState = digitalRead(buttonPin);
// check if the pushbutton is pressed.
// if it is, the buttonState is HIGH:
if (buttonState == HIGH) {
// turn LED on:
digitalWrite(ledPin, HIGH);
count = count + 1;
Serial.print(count);
}
else {
// turn LED off:
digitalWrite(ledPin, LOW);
}
}
I dont know why count is coming absurdly and unevenly.
|
I have an RC car. The battery provides power to the ESC and then the ESC provides 6 V back out to the receiver. Instead of the receiver I have a Raspberry Pi, which uses the 6 V, steps it down to 5 V and provides power to the Raspberry Pi.
The problem
Every time we go full power*, there is a lack of voltage and the Raspberry Pi seems to hard reset.
* By full power we mean direct to 100% and not ranging from 0-100
I am not an expert in electrical circuits, but some of the suggestions are to use a capacitor to provide the missing 5 V in the interim. How do I prevent the Raspberry Pi from dying in the event of full power?
|
I could swear that it was working for a while. I got back to my desk, tried it again, and it's no longer working. Could I have fried the NO pins on both sides? This is a DPDT relay. Everything works normally on the NC pins. I have never applied more than 5V. I do hear the relay click when I apply 5V to the coil. But when I measure voltage on the NO pins, I get 0V. Has anyone else seen this? I have two of these relays and I can't seem to get voltage on the NO pins with either relay. I should clarify that I'm expecting the same 5V power source to power both the coil and the common pins. If the NC pins work then I don't see why the NO pins shouldn't. In both cases the 5V is shared between the coil and any load attached to the NC/NO pins. I did try driving the entire circuit off a 9V power supply, but that did not change the results (and that does contradict my earlier statement that I've never applied more than 5V to this relay). My circuit is based on Charles Platt's "Make: Electronics", p. 59.
Here's a pic of the schematic I am following, except that I am using a 5V relay and a 5V power supply (USB port) and I am using piezo buzzers without resistors instead of LEDs.
|
I'm looking for particle filter implementation in ROS to use in mobile robot localization, but it seems the only available package is amcl (Adaptive Monte Carlo), I'm not sure is it possible to use it as particle filter or not, and if it's feasible, how?
Note: The robot (wheeled robot) provides odometry data and another data source is Kinect, that provides visual odometry data using fovis.
|
I frequently bang my head on my desk after performing a task poorly. I would like to eliminate the unnecessary middle step of actually performing a task poorly. As such, I would like to design a system to hold my head and repeatedly strike it against my desk. Alternatively, a system that holds the desk and repeatedly strikes it against my head would be acceptable. Requirements are at least 2 strikes per second maximum with ~50cm travel.
Can anybody make any recommendations for a system to base this device off of? Denso products, while small and affordable, do not have the required load capacity (some users may have a rather large head, and involuntary resistance is to be expected -- at least near the start of the cycle). I am thinking of something more industrial, perhaps:
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I am looking for some material to build a soft clear protective covering for RGB LEDs. The material needs to be close to transparent to allow light to shine through, be soft and compliant but sturdy enough to withstand someone standing on it. The ultimate goal is to have a floor of these LEDs that someone can jump in barefoot and change led colors.
I have tried Gel Candle Wax and Silicone but neither worked very well. I am looking for other material ideas and this was the most relevant of the StackExchanges that I could find.
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I am using Arduino UNO to read a push button every time it is pressed.Earlier i was simply reading the Digital IO pin to read the count and then i faced the condition of switch debounce regarding which i had asked a question here and get to know that i must use Interrupt instead of reading a digital IO pin but even after using interrupt, i was facing the problem of Switch Debouncing.
So i used this link and code given on this link
const int buttonPin = 2; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin
// Variables will change:
int ledState = HIGH; // the current state of the output pin
int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin
// the following variables are long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
long lastDebounceTime = 0; // the last time the output pin was toggled
long debounceDelay = 50; // the debounce time; increase if the output flickers
void setup() {
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
// set initial LED state
digitalWrite(ledPin, ledState);
}
void loop() {
// read the state of the switch into a local variable:
int reading = digitalRead(buttonPin);
// check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited
// long enough since the last press to ignore any noise:
// If the switch changed, due to noise or pressing:
if (reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer
// than the debounce delay, so take it as the actual current state:
// if the button state has changed:
if (reading != buttonState) {
buttonState = reading;
// only toggle the LED if the new button state is HIGH
if (buttonState == HIGH) {
ledState = !ledState;
}
}
}
// set the LED:
digitalWrite(ledPin, ledState);
// save the reading. Next time through the loop,
// it'll be the lastButtonState:
lastButtonState = reading;
}
and change
long debounceDelay = 50;
to 10(means read any thing ina time gap of 10 mili second) as the code says.Now what is happening, code is running on the board and after some time my board get hang and LED stop toggling on any press of push button and then i had to manually reset my board.I also want to add upon a thing that i am also using a serial port in between when LED toggles or switch is pressed.
I am totally confused why this is happening.There can beone possibility that this is happening because i reduced time gap between two consecutive events to 10 from 50 miliseconds and that might be making AVR get hanged and thus require a manual reset.
|
I have a bag file that contains couple of topics needed for localization, odometry data, kinect data and /tf. What I want is watching robot's movement path in rviz after initializing robot position (even I don't know how to initial it). Any help?
All topics:
/scan
/tf
/clock
/map
/odom
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I am making a mobile base for a robot with wheels. I want to use a Kinect like a movement sensor (to avoid obstacles, recognition of people, etc...) but I read that there is 2 models, the 360 and the Developer.
Which Kinect works well for my job? And another thins, its there another thing that can I use like a movement sensor? To see diferent posibilities,
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For a certain robotic application (actually for the FTC challenge this year) our team is performing an operation where a servo-driven arm could potentially be forced into an unknown position. We are using NXT+Tetrix.
Since this could damage a powered servo working against this forced position (servo holding arm weight on fixed base is now trying to move heavy base relative to fixed arm), we are thinking about somehow de-powering our servos (or servo controller), in order to get the servos to "relax" and accept the mechanically-forced position.
Originally, we were thinking of having our RobotC code determine the physical position of a given servo and set its desired position to there every loop, limiting how much a servo would try to fight the movement, but to our dismay, ServoValue[fooServo] actually gives us the setpoint, and not the physical location (due to the servo being unable to provide this information).
We also considered setting ServoChangeRate[fooServo] to 1(the minimal value) but this only changes the rate of the target location changing relative to the previous target.
So, we're concluding that the only way to really do this is to fully depower the servos. Is this possible on NXT/Tetrix with RobotC?
A few notes:
I realized as well that one could suggest to rig an encoder(associated with a Tetrix motor that does not need an encoder) onto the rotating area. That actually would not work for mechanical constraints.
I looked into setting PWM enable as shown here but am not sure how to send the i2c commands needed. If someone could clue me in to how these commands would be sent in terms of c code, that would be very helpful.
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