Quote:
Originally Posted by JustineSHA
...we also don't understand why at (20,0) one motor is faster than the other, and we move backwards.
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The proper direction of motor control depends on which way you've wired your motors. The code can't know that unless you tell it. Isn't there a check box or two in the Drive setup block to select "reverse direction" on the output motors? One of them is probably checked. It sounds like you need to uncheck that one and check the other.
There are two common reasons for one motor to be faster than another with the same pwm control value. Some motors have a direction bias, and turn "forward" faster than they turn "backward". You probably have the motors mounted so one has to turn in the other direction from the other in order for both sides of the robot to go the same way, right? But you also probably are using the CIM motors for your main drivetrain, and those don't have a significant bias.
The other likely reason is that the Victor calibration thinks that neutral is a little bit higher than the 127 value the Robot Controller is putting out. If you go just a small amount away from neutral on the RC, and you've told the software that "forward" is one way on one motor and the other way on the other motor, one Victor sees a smaller "plus" control and the other sees a larger "minus" control. You can probably fix this by calibrating the Victors; the procedure is in the
Victor 884 Users Guide on the
IFI web site.