Kirk Wallace wrote: > I connected the motor to my lab supply and got the motor to turn very > slowly at about 4.5 Volts. At the slowest speed, it would only stop if I > reduced the voltage. So I guess I have a "good" motor and I just need to > work more on the tuning. Maybe, add more P to get the initial voltage up > to 4.5 but then add more D (?) to fight the oscillating. Well, I wanted > a real world test bed, I guess I got it. >
Right, you want P as high as possible, and to the point that you need some D to prevent oscillation. Unfortunately on the Pico Systems PWM system, there is no current loop or tach feedback, so the tuning is a little bit more touchy than with velocity servo amps. But, usually you can get the following error down to really negligable levels and still have a stable servo response. Too much D and the whole system gets quite unstable due to lags in the loop and the effects of quantization of the encoder. Once you have P and D up about as high as you can get them, you reduce the rest of the errors with FF1 and FF2. It doesn't take much of these factors to make quite a difference, and it is easy to go too far and make things worse. And, you need something like 1 - 2 encoder counts worth of deadband to stop the buzzing. Jon ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
