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Torquenado motor speed - piece to piece variation

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  • Torquenado motor speed - piece to piece variation

    It is the second year of FTC for our team and we decided to learn how to use a mecanum drive for our chassis. We constructed it using torquenado motors (we had these from last year) and built a basic code to drive using all 4 motors. We found that all 4 motors rotate at significantly different speeds when given the same power input (even dis-connected from the chain drive). Has anyone notice this variation in base speed of the Torquenado motors or know what could be causing this ?

    We plan to switch the Neverest this year but nevertheless would like to understand this motor anomaly.

  • #2
    Try setting the run mode of all four drive motors to RUN_WITHOUT_ENCODER.

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    • #3
      In the code we already have it set to RUN WITHOUT ENCODERS. Thanks for the suggestion though.

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      • #4
        Can you write a simple opmode that displays encoder counts per second of each drive motor and/or final count after 30 seconds (still using RUN_WITHOUT_ENCODER run mode and motors at full power with no load on the motors).
        Last edited by Alec; 09-03-2019, 11:29 AM.

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        • #5
          Perhaps someone can explain why this would be attempted with raw power to the motors? I would expect that there is always some variation from motor to motor and such would only get worse with the age of the motor. But... if you are using the encoders to control the relative speed, one could use different motors as long as the counts per output revolution is the same.

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          • #6
            Originally posted by noviroboteks View Post
            It is the second year of FTC for our team and we decided to learn how to use a mecanum drive for our chassis. We constructed it using torquenado motors (we had these from last year) and built a basic code to drive using all 4 motors. We found that all 4 motors rotate at significantly different speeds when given the same power input (even dis-connected from the chain drive). Has anyone notice this variation in base speed of the Torquenado motors or know what could be causing this ?

            We plan to switch the Neverest this year but nevertheless would like to understand this motor anomaly.
            Have you checked actual power draw of the motors? Power them from an independent supply or put a current monitor on the wires. Speed variations, especially unloaded or very lightly loaded, can be quite high depending on the friction in your wheel/gear train. Have you run in the gears (dry) for about 30 minutes already? Did you lube them afterwards? Sealed bearings or bushings on your hubs? Chain/belt tension? I could go on but there are other things that will mess with the speeds. Perhaps rig the motors in a fixture where you can control everything else, then retest monitoring actual power at a fixed RPM.
            Technical Coach, Newton Busters FTC 10138, FLL 3077
            Chicago 'burbs, IL

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