On Sunday 19 September 2021 20:12:01 Chris Albertson wrote: > Is the PID controller running on the PC under LCNC or is this an > external PID controller you built? > The pid is the stock lcnc pid,
> What are the numbers, the loop period, motor speed and numer of > encoder lines. and so on? from the .ini file: #******************** # Axis A #******************** [AXIS_A] MAX_VELOCITY = 30.000 MAX_ACCELERATION = 1500.00 [JOINT_3] TYPE = ANGULAR HOME = 0.0 HOME_SEQUENCE = 3 HOME_SEARCH_VEL = 9.0 HOME_LATCH_VEL = -1.0 HOME_FINAL_VEL = 30 HOME_OFFSET = 4.498500 VOLATILE_HOME = 1 FERROR = 0.50 MIN_FERROR = 0.25 MAX_VELOCITY = 30.000 MAX_ACCELERATION = 1500.00 P = 6000 I = 1.700 D = 0.7500 FF0 = 0 FF1 = 21.5 FF2 = 0.55 BIAS = 0 DEADBAND = 0.00015 BACKLASH = .00001 MAX_OUTPUT = 900.0000 SERVO_SCALE = 666.6666666666667 PWMGEN_TYPE = 2 Loop period is stock, 1 kilohertz. I've tried up to 4k, but it didn't help > I don't think the fact that there is a worm gear matters. The > problem, I bet is the large inertia of the system. Thats my assessment too. Throw in a bit of worm friction and it stops, still spitting out .1% to 1% drive, not enough to actually entice it to move once stopped. > Aside from proper tuning of the PID gains you could change the system > to use a nested or "cascade" PID. THis allows the velocity setpoint > to be controlled by the position error > see the section "cascade" in the wiki article > https://en.wikipedia.org/wiki/PID_controller I looked at that 6 months ago, and quickly got lost. > I think you want a very fast loop i=for the inner PID. LIkely it > wouldbe in external hardwarelike a microcontroller or FPGA. (does > MESA do the PID algorithm in the FPGA? It should.) But it doesn't that I know of. Thanks Chris. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
