On 9 June 2013 23:05, Gene Heskett <[email protected]> wrote: > With my limited understanding I'm assuming the with FF0=100, and all the > other trimmers setp'd to 0.0000, that it should have a straight thru > transfer function, ignoring any feedback from the encoder velocity pin.
Yes, you should. > However, with the motor driver disconnected so there is no input from the > encoder, the output voltage steps at the C41 output aren't truly linear > either. What is the PID output doing? That should be completely linear, which suggests that the nonlinearity is in the pwm-voltage stage (and I would be astonished if that circuit was actually linear). > I am beginning to get the impression this controller might need a buildout > resistor in the control voltage wire. If you do have active PID then the nonlinearity is a non-issue. If all plants had linear, well characterised response curves then there would never be any need for PID control. If you do want to linearise the transfer function, you could look at the lincurve hal module. Designed for just this sort of application. http://www.linuxcnc.org/docs/devel/html/man/man9/lincurve.9.html -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. A cloud service to automate IT design, transition and operations 2. Dashboards that offer high-level views of enterprise services 3. A single system of record for all IT processes http://p.sf.net/sfu/servicenow-d2d-j _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
