Sometimes the feedback polarity is correct (the motor does not attempt to run away) but the
direction of motion is reversed with respect to the commanded motion. If this is the case, reverse
the motor leads AND the encoder signals.
If the motor moves in the required direction but stops short of the target, it is most likely due to
insufficient torque output from the motor command signal ACMD. This can be alleviated by
reducing system friction on the motors. The instruction:
TTX (CR)
Tell torque on X
reports the level of the output signal. It will show a non-zero value that is below the friction level.
Once you have established that you have closed the loop with the correct polarity, you can move
on to the compensation phase (servo system tuning) to adjust the PID filter parameters, KP, KD
and KI. It is necessary to accurately tune your servo system to ensure fidelity of position and
minimize motion oscillation as described in the next section.
DMC-1600
Chapter 2 Getting Started
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