Maybe everyone knows this already, but I just discovered that those closed-loop stepper motors have a few dozen adjustable parameters.
It seems the controller has a few nested PID loops. One is for current, one for the position and a velocity PID and all allow user-settable P, I add D parameters. There is a separate PID for the case when the motor is stationary or as they call it "locked". This is disabled at the factory, (I think) There is a graphical tool for plotting commanded vs actual position vs time. It will also show an FFT or spectra of this which would help if you were looking for resonances. This would help a lot for tuning. You could watch the error signals in real-time and change the tuning. You can also set the tolerance for error before the alarm and about a dozen other things like set bias for holding against gravity. A "virtual gear ratio" and you can reprogram the number of micro-steps when all the switches are "up". They advertise a 1000 line per revolution encoder but I notice the factory setting is for 4000 lines. They must be looking at all four edges from both A and B phases. So they get and effective 4000 line per rev. One thing I noticed is the PID is tuned out of the box to be very "soft". The allowed range of constants is 0...65000 and it is factory set at about 200. It is possible to completely mess up the operation of the motor by putting in nonsensical values so there is a big "reset to factory" button. I suspect the motor actually runs best with factory settings in most cases. Parameters are stored in EEPROM and can be read and written. The software I suspect comes from Leadshine and gets re-branded for all the stepper motor resellers. It is a Windows .exe file but I don't own a Windows PC. It runs fine on My Mac and Linux systems using a virtual machine. Close_Loop_Stepper_Drive_V2.14.3.zip <https://www.omc-stepperonline.com/download/Close_Loop_Stepper_Drive_V2.14.3.zip> -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
