Jon Elson wrote: > 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. >
Don't you use _any_ Integral gain? I guess there are as many ways to tune as there are people, but I can't imagine not using I gain. In fact the drives that I work on in my day job tend to use P and I only. No D, no FF. Of course these aren't servo drives, just simple speed loops for the most part. Regards, John Kasunich ------------------------------------------------------------------------- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
