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Sync motors

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  • Sync motors

    How do you sync two Tetrix motors? I know how to sync two NXT motors, but I cannot figure out how to sync the Tetrix motors.


  • #2
    Tetrix Motor Sync

    Originally posted by 2010FTC4081 View Post
    How do you sync two Tetrix motors? I know how to sync two NXT motors, but I cannot figure out how to sync the Tetrix motors.

    At both RobotC training and LabView training that I attended in the last few months, I was told that synchronizing Tetrix Motors is not a feature of either programming package.

    I gather that the synch capability is built in to the NXT brick somehow for the LEGO motors and not built in to the motor controller for the Tetrix motors (i.e. the HiTechnic DC Motor Controller).

    If you are ambitious, I think you could implement the Sync algorithm in your program, using the encoder values reported from the HiTechnic motor controller and setting the desired power values. That won't be as good as it could be if it was implemented inside the controller because of the time delays reading the encoder values and calculating new power values which will be incurred over the I2C sensor bus, etc.

    In our team's experience, going straight is highly overrated anyway. You are probably better off to go "sort of" straight and use other mechanisms to find your way around the field. Even if both of your wheels turn the same number of times going over the mountain, you aren't likely to be going straight due to differences in traction, etc.

    All that aside, perhaps some words of encouragement to HiTechnic would get them to implement a synch capability in the controller in the future (or maybe open the firmware up for other people to extend). There is more to the motor controller than is made (obviously) available through RobotC or LabView and if you send HiTechic an email, they will probably send you a detailed specification on it. Notably, you can change the P, I, D values, but they have picked pretty good ones for what they expect us to do with them. (but if your application deviates significantly from "normal" perhaps you can pick better ones).

    Best regards,
    David Fort
    Mentor, Team 1001
    Brush High School
    Cleveland, OH USA


    • #3
      Are you talking about programming the motors to check if they're going straight (as wonderfully covered above, thank you David), or about making two motors move the same direction and same rate (i.e. on one side of the drive train)? Because if it's the latter, it is solved by soldering the motor wires for two motors together in a circuit.