lloyd wilson wrote: > We are investigating using my favorite cnc controller for an application > which will require as much stiffness as we can arrange; websearching > suggests that torque mode rather than velocity mode is preferrred in > such applications. We are using a Pico PPMC interface set to mediate > between the computer and a Parker Aries amp/motor combination (+/- 10v > control input, 2000 line encoder, vendor rep loaded any requisite motor > parameters into the amp). We finally have the system so it doesn't > immediately fault on a following error, but only in velocity mode; we've > been totally unable to generate a set of PID parameters that are viable > when the amp is set to torque mode. Ergo, it's guru time- > What, exactly, is the problem? Is it unstable? Torque mode is going to be less stable that velocity mode, I think. It will require more careful tuning of the P and D parameters, and when you get the P as high as you can go while still having good stability, you then need to use FF1 and FF2 to improve on that. But, that won't improve stiffness against external torque.
There may be as much or more tweaking required on the Parker amp as in LinuxCNC to get the best results. I agree with Dave that I don't see any reason why torque mode should be stiffer than velocity mode. Velocity mode moves one more control loop out to the drive, which likely has a higher servo update rate than LinuxCNC, so that can be helpful. 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
