hey guys just looking for a config example if possible for a mesa card from someone that has this nested PID loop setup.
internal PID loop uses servo motor encoder and the outer Pid loop only uses the Intergral value with the scale and then they get summed together to drive the motor I found this link here on the forum and want to try set it up http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Combining_Two_Feedback_Devices_On_One_Axis This page shows how to combine two position feedback devices into two PID's for the tuning and positioning of one axis. 1. This example has one high resolution linear scale on the axis table and one rotary encoder on the axis drive motor. 2. This could also be a rotary encoder on the ballscrew and a rotary encoder on the motor 3. This assumes the PID's are loaded and connected to the servo thread 4. linear scale position feedback connects to the input of the pid.4 PID 1. net X-linear-pos-fb 'linear position feedback' pid.4.feedback 5. motor encoder position feedback connects to the feedback input of the pid.0 PID 1. net X-motor-pos-fb 'axis motor position feedback' pid.0.feedback 6. position command signal from LinuxCNC axis connects to both PID command inputs 1. net Xpos-cmd axis.0.motor-pos-cmd pid.0.command pid.4.command 7. bit signals from LinuxCNC axis connnects to enable/disable both PID loops 1. net Xenable axis.0.amp-enable-out pid.0.enable pid.4.enable 8. set PID loop output limits as specified in ini file 1. setp pid.0.maxoutput [AXIS_0]PID_MAX_VEL 2. setp pid.4.maxoutput [AXIS_0]PID_MAX_VEL 9. set the motor encoder PID loop gains 10. NOTE - I gain is set to zero - it would fight the other PID 1. setp pid.0.Pgain [AXIS_0]P 2. setp pid.0.Igain 0 3. setp pid.0.Dgain [AXIS_0]D 4. setp pid.0.bias [AXIS_0]BIAS 5. setp pid.0.FF0 [AXIS_0]FF0 6. setp pid.0.FF1 [AXIS_0]FF1 7. setp pid.0.FF2 [AXIS_0]FF2 8. setp pid.0.deadband [AXIS_0]DEADBAND 9. setp ppmc.0.DAC.00.scale [AXIS_0]OUTPUT_SCALE 11. set the linear scale PID loop gains 12. NOTE - it has only I gain - all other gains are set to zero 1. setp pid.4.Pgain 0 2. setp pid.4.Igain [AXIS_0]I 3. setp pid.4.Dgain 0 4. setp pid.4.bias 0 5. setp pid.4.FF0 0 6. setp pid.4.FF1 0 7. setp pid.4.FF2 0 8. setp pid.4.deadband [AXIS_0]DEADBAND 13. connect both PID output signals to sum2.4 inputs 14. sum the outputs of pid.0 and pid.4 15. pid.0 is using motor encoder feedback 16. pid.4 is using linear scale feedback 1. net Xoutput-motor pid.0.output sum2.4.in0 2. net Xoutput-linear pid.4.output sum2.4.in1 17. the summed PID output is connnected to the DAC input signal 1. net Xoutput sum2.4.out 'DAC input' 18. repeat as necessary for more axes _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
