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Comments by Brandon
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Brandon's line following robot: The Chariot
- 28 February 2018Hello, cpod.
The Chariot and Mostly Red Racer (the winner of the competition) both used PD control (no integral). The integral term is useful for counter-acting some external force consistently working against the robot. When following a line, you do not typically have that kind of constant force working against your robot's goal, so in most cases you can simplify by leaving out the Integral term.
I find it easiest to start tuning at a somewhat slow speed and gradually increase your speed once your P and D coefficients are working fairly well. At slow enough speeds, you probably don't need a D term at all, especially for a relatively straight line. If you want to be able to drive quickly around sharper turns, you will need your P term to be large, which will likely cause an overshoot. This is where the D term comes in to compensate. Essentially, the D term takes a history of the error and reacts to the change accordingly. If the error is getting smaller, it acts to weaken your robot's response to avoid overshoot. Similarly, if the error is getting bigger, the D term should act to increase your robot's response. There are a lot of good tips for tuning in Ben's posts in this thread. You might consider creating your own thread on our forum if you run into more specific questions when tuning your robot.
Brandon
Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers
- 29 January 2018Hello, servane.
When setting the VREF voltage, you can connect the driver as shown in the minimal wiring diagram found on the product page for each stepper motor driver carrier, excluding the motor connections. Once the current limit is configured appropriately, you can momentarily remove power and then connect your motor as well.
If you have additional questions about using one of our stepper motor driver carriers, I recommend posting a request for help on our forum.
Brandon
New product: Sharp 15cm GP2Y0D815Z0F digital distance sensor
- 25 January 2018Hello, Peter.
Theses GP2Y0D815Z0F sensors output a simple digital signal (low when detecting an object, high otherwise), so you can use Arduino's digitalRead() function to read them. For controlling motors, your Arduino code would depend on what kind of driver/controller you are using and what you wanted the motors to do based on the sensor reading. If you have specific questions or concerns, you might consider posting on our forum , which is a more appropriate place for discussing details like code.
-Brandon
Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers
- 22 December 2017Hello, Aatif.
I am glad you liked the video! Sorry you are having problems with your DRV8825 carrier. There are several things that could be causing a problem like that, including stepping too fast for your motor or having too heavy of a load. If you would like help troubleshooting the problem in more detail, you can post on our forum with more information about your system as well as pictures of your setup and we would be happy to help.
Brandon
New product: Pololu Dual MC33926 Motor Driver for Raspberry Pi
- 18 October 2017Hello.
The regulator is optional and allows the Raspberry Pi to be powered from your motor power supply. If you are powering the Raspberry Pi separately (e.g. through its USB power connector), you do not need the regulator.
You can find more information about adding the regulator in the "Powering the Raspberry Pi from the motor driver board" section of the Dual MC33926 Motor Driver for Raspberry Pi product page.
Brandon
Brandon's mini sumo robot: Black Mamba
- 21 August 2017Hello, Costi.
You might find our "Force and Torque" blog helpful when selecting the right gearmotor for your robot. One key factor to consider is that the speed and pushing force of your robot will depend on the size of your wheels. For example, a larger diameter wheel will cause the robot to travel faster, but have less pushing force. The actual pushing force you get could also be limited by traction, so using too high of a gear ratio for the extra torque might not be as beneficial at some point since your wheels/treads will likely start slipping on the surface.
For reference, we typically recommend the 50:1, 75:1, or 100:1 HP micro metal gearmotors for use with our Zumo robots, which is often used in mini sumo competitions. For a slower Zumo that has the potential to deliver more torque, the 100:1 HP (or the 100:1 HPCB) micro metal gearmotor would be a good choice. I probably wouldn't recommend going too much higher than that since the reduced speed would likely be hard obstacle to overcome, and even in head-to-head battles, slipping could start limiting your pushing force, so you might not be able to effectively use the increased torque.
Brandon
Motion tracking skull Halloween prop
- 19 June 2017Hello, Veronika and Mascha.
I do not have any specific advice for using a camera and a Basic Stamp to do a project like this; I suspect it will be a much different experience than I had doing this project. If you run into problems or have more specific questions, you might try posting on our forum. However, since the Basic Stamp is made by Parallax you will probably get better results posting on theirs.
Brandon
New products: Scooter/Skate Wheels
- 25 May 2017We do not make those wheels ourselves, and unfortunately, we do not have models for them.
-Brandon
Brandon's line following robot: The Chariot
- 23 May 2016Hello, James.
I am glad you are interested in my design! I made my design files for the laser-cut pieces available via Thingiverse; you can use this link to access those files when they are available (this is my first time uploading and publishing a creation on Thingiverse, and they require a minimum wait time of 24 hours between account creation and publishing your first creation, so you might have to wait until around this time tomorrow).
For the mechanical components, you can find 3D models for the motor and motor bracket on their respective product pages. We do not currently have models available for the wheels or ball caster, although it is something we are looking into. For now, you can find dimension diagrams for them on their respective product pages. Please let me know if I left something out or you have any additional questions.
Brandon
Brandon's line following robot: The Chariot
- 25 March 2016Hello.
I do not currently have my code available; however, as I mentioned in my last comment, my code is based on our example line follower code for the Zumo Robot for Arduino, V1.2. Other than converting the motor commands into the corresponding TTL serial commands for the Qik 2s9v1 motor controller, the biggest change I made to that code was probably tuning the PID coefficients. Since this varies for every system, I suspect my code would not be any more helpful than that sample code.
I see you also posted a request for help on our forum. That seems like a more appropriate place to continue the discussion if you have more questions.
-Brandon