Comments by Brandon

  • Brandon's line following robot: The Chariot

    Brandon's line following robot: The Chariot

    - 17 September 2018

    I do not have a schematic diagram for this robot, but the connections are fairly straight forward. The rocker switch is wired between the battery and the input of the regulator. The output of the regulator is powering the Qik motor controller and A-Star 32U4 Mini. The QTR sensor array is powered from the 5V pin on the A-Star 32U4 Mini. The rest of the connections depend on what pins you are using to read the sensors and send serial signals to the motor controller. If you have more specific questions when you start your line follower, you can post a request for help on our forum, and we would be glad to help there.

    You should be able to swap an Arduino Uno in for the A-Star 32U4 in this system, but it is much larger, so you would probably need to find a different way to mount it.

    Brandon

  • Brandon's line following robot: The Chariot

    Brandon's line following robot: The Chariot

    - 27 August 2018

    I noticed you posted similar questions on our forum; I have responded to it there. We can continue the conversation in the forum thread you created since it is probably a more appropriate place for a detailed discussion.

    Brandon

  • Brandon's line following robot: The Chariot

    Brandon's line following robot: The Chariot

    - 24 August 2018

    It sounds like you have it correct, except I powered the whole system (including my microcontroller) from the 7.5V D24V25F7 step-down regulator. I used a connector to attach the battery to my robot so it could be removed and charged separately. The positive wire from the connector runs through the rocker switch and to the voltage regulator, and the ground wire goes straight to the regulator. The output of the regulator providing power to both the Qik 2s9v1 Dual Serial Motor Controller and the A-Star 32U4 Mini LV.

    I did not use any low-voltage cutoff circuitry. I was careful to not run the robot for too long between charges, and in general it only runs for a couple minutes at a time, so it was easy to check the battery regularly. I considered adding a simple voltage divider from the battery to one of the free pins on the A-Star 32U4 Mini to alert me (with an LED) when the battery voltage dropped too low, but it did not seem necessary for the short run time.

    Brandon

  • Brandon's line following robot: The Chariot

    Brandon's line following robot: The Chariot

    - 28 February 2018

    Hello, 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

    Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers

    - 29 January 2018

    Hello, 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

    New product: Sharp 15cm GP2Y0D815Z0F digital distance sensor

    - 25 January 2018

    Hello, 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

    Video: Setting the Current Limit on Pololu Stepper Motor Driver Carriers

    - 22 December 2017

    Hello, 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

    New product: Pololu Dual MC33926 Motor Driver for Raspberry Pi

    - 18 October 2017

    Hello.

    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

    Brandon's mini sumo robot: Black Mamba

    - 21 August 2017

    Hello, 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

    Motion tracking skull Halloween prop

    - 19 June 2017

    Hello, 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

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