Peter C. Wallace wrote: > > > No, but a torque mode PID loop is also responsible for velocity control. This > is handled by a separate high speed loop in your drive when your drive is in > velocity mode. A Torque mode PID loop often needs to to run at a higher > sample > rate than a PID loop controlling a velocity mode drive. That is to say > LinuxCNCs 1 KHz default servo thread rate may be marginal for a torque mode > drive (not enough phase margin for the D term). > It is possible to turn up the servo rate by reducing SERVO_PERIOD in the .ini file. 2 KHz should be easy, 4 KHz should be possible with a PCI plug-in parallel port, but may not work with the on-motherboard port. > Also because a torque mode PID control loop depends so much on the D term, > its > helpful if the velocity feedback is a good as possible. I'm pretty sure the > PPMC has velocity estimation (as opposed to plain old crunchy dp/dt) No, it doesn't. The only one of our boards that has this, NOW, is the Universal PWM Controller. I plan to put it into the other boards soon. But, until the release of 2.5, users would have had to run a developer's version of LinuxCNC to use this feature, it was not in the driver for 2.4.x.
Jon ------------------------------------------------------------------------------ For Developers, A Lot Can Happen In A Second. Boundary is the first to Know...and Tell You. Monitor Your Applications in Ultra-Fine Resolution. Try it FREE! http://p.sf.net/sfu/Boundary-d2dvs2 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
