[3.6.0beta.2] Errors in Close loop tuning
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Hi,
I’m experiencing issues with axis tuning. The mechanical setup is as follows:
A motor with an integrated brake and quadrature encoder.
A coupling connects the motor to a leadscrew.
A magnetic encoder is mounted on the opposite end of the motor due to limited access to the axis.
The calibration fails, likely due to backlash or counts/step mismatch. Here are the errors I’m seeing:Power up + 00:00:29 [warn] Error: Driver 122.0 calibration failed, measured backlash (0.639 step) is too high.
Power up + 00:00:29 [warn] Warning: Driver 122.0 failed to maintain position, tuning/calibration failed.
Power up + 00:00:25 [warn] Error: Driver 122.0 calibration failed, the measured motion was less than expected, measured counts/step is about 66.8.Is there a way to use only the quadrature encoder for calibration to bypass the backlash issue?
How can I resolve those problems?BR.
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@Paski to confirm for anyone else reading this following our email exchange:
- That backlash is too high for successful calibration where the encoder is being used for motor commutation.
- There is inevitably backlash in a system where there is a coupler and then a leadscrew between the motor and the encoder.
- Using an encoder on the motor is effectively required for a well behaved system, adding a second encoder on the axis for position loop closing is supported but that can't be the only encoder.
Also, depending on axis length, and the position of the 1HCL, the SPI cable may be too long to be reliable, although thats not the specific issue in this case
