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ROMI left and right motor way off

I’ve purchase the ROMI for the FRC kit ( #4022 Romi Robot Kit for FIRST.

My ROMI seems to be really off and the left motor and right motor does not spin anywhere near the same speed at all (it always curve Right significantly). Just wondering if this is a common thing and is to be expected or do I have a bad motor or something else?


It is normal for brushed DC motors to have some unit-to-unit variation in speed, so you should not expect a differential drive robot to go straight unless you have calibrated for that (e.g. by empirically determining an offset between the two speeds for your particular combination of motors) or you are using closed-loop feedback (e.g. encoders) so you’re controlling the actual speed of the motors rather than just the voltage to them.

In additional to unit-to-unit variation, it is normal for DC motors to be slightly faster in one direction than the other just based on internal geometry.

Can you quantify the difference in speeds between the two motors?