Is it possible to adjust 1000Hz PID cycle time on v2.1 firmware?

2 years 3 months ago - 2 years 3 months ago #29535560 by mpthompson
Our hardware environment is two Maxon BLDC drive motors controlled from SBLM2360T with the v2.0 and v2.1 firmware.

With the SBLM2360T controller we have been using Maxon BLDC motors with 12:1 gear reduction and 2048 count encoders without issue for driving our robots in position/speed closed-loop mode.  However, due to supply chain issues we are now attempting to use the same BLDC motors, but with 6:1 gear reduction or with encoders with 1024 tick counts.  In both instances, the control of our robot at low speeds has degraded significantly. After substantial investigation, it seems that the issue is that because of the reduced gear reduction or reduced encoder counts with these new motors, the control problems we are experiencing are related to RoboteQ running a 1000Hz PID control loop.  At 1000Hz, there aren't enough encoder ticks for the RoboteQ to get meaningful position/velocity for closed-loop control of the motors at low speeds.

My question is: Is there a way to reduce the PID control loop on the RoboteQ to something such as 500Hz rather than 1000Hz with the v2.0 or v2.1 firmware?  The closest thing I can think of is in the v2.1 firmware is the "INT - Interpolation Time Period (DS402)" command which changes the interpolation time.  However, from the documentation it isn't clear if this actually changes the PID control loop frequency, or is the interpolation used in some other way unrelated to PID control?

Hopefully I'm barking up the right tree on this. Any suggestions or help would be greatly appreciated.

Mike Thompson


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