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more spindle servo tuning questions
Posted: Fri Jun 28, 2024 6:13 pm
by turbothis
i had the idea to run a load test on the spindle by ramming a large bolt head (in tailstock) into a large round bar in the spindle to see how it reacts
the spindle ramped up the DAC and it responded pretty nice
now i run a simple program with light cuts and the spindle will start running off and react terribly
what is the difference in the 2 tests?
Code: Select all
#include "KMotionDef.h"
#include "MySpindleDefs.h"
//#include "CSSJog.c"
int main() {
// X axis
ch0->InputMode=ENCODER_MODE;
ch0->OutputMode=DAC_SERVO_MODE;
ch0->Vel=80000;
ch0->Accel=5e+06;
ch0->Jerk=5e+06;
ch0->P=5;
ch0->I=0;
ch0->D=20;
ch0->FFAccel=0;
ch0->FFVel=0;
ch0->MaxI=200;
ch0->MaxErr=200;
ch0->MaxOutput=500;
ch0->DeadBandGain=1;
ch0->DeadBandRange=0;
ch0->InputChan0=0;
ch0->InputChan1=0;
ch0->OutputChan0=0;
ch0->OutputChan1=0;
ch0->MasterAxis=-1;
ch0->LimitSwitchOptions=0x100;
ch0->LimitSwitchNegBit=0;
ch0->LimitSwitchPosBit=0;
ch0->SoftLimitPos=1e+09;
ch0->SoftLimitNeg=-1e+09;
ch0->InputGain0=1;
ch0->InputGain1=1;
ch0->InputOffset0=0;
ch0->InputOffset1=0;
ch0->OutputGain=1;
ch0->OutputOffset=0;
ch0->SlaveGain=1;
ch0->BacklashMode=BACKLASH_OFF;
ch0->BacklashAmount=0;
ch0->BacklashRate=0;
ch0->invDistPerCycle=1;
ch0->Lead=0;
ch0->MaxFollowingError=1000000000;
ch0->StepperAmplitude=250;
ch0->iir[0].B0=1;
ch0->iir[0].B1=0;
ch0->iir[0].B2=0;
ch0->iir[0].A1=0;
ch0->iir[0].A2=0;
ch0->iir[1].B0=1;
ch0->iir[1].B1=0;
ch0->iir[1].B2=0;
ch0->iir[1].A1=0;
ch0->iir[1].A2=0;
ch0->iir[2].B0=1;
ch0->iir[2].B1=0;
ch0->iir[2].B2=0;
ch0->iir[2].A1=0;
ch0->iir[2].A2=0;
// Z axis
ch1->InputMode=ENCODER_MODE;
ch1->OutputMode=DAC_SERVO_MODE;
ch1->Vel=130000;
ch1->Accel=5e+06;
ch1->Jerk=5e+06;
ch1->P=10;
ch1->I=0;
ch1->D=20;
ch1->FFAccel=0;
ch1->FFVel=0;
ch1->MaxI=200;
ch1->MaxErr=200;
ch1->MaxOutput=1000;
ch1->DeadBandGain=1;
ch1->DeadBandRange=0;
ch1->InputChan0=1;
ch1->InputChan1=0;
ch1->OutputChan0=1;
ch1->OutputChan1=0;
ch1->MasterAxis=-1;
ch1->LimitSwitchOptions=0x114;
ch1->LimitSwitchNegBit=11;
ch1->LimitSwitchPosBit=0;
ch1->SoftLimitPos=1e+09;
ch1->SoftLimitNeg=-1e+09;
ch1->InputGain0=1;
ch1->InputGain1=1;
ch1->InputOffset0=0;
ch1->InputOffset1=0;
ch1->OutputGain=1;
ch1->OutputOffset=0;
ch1->SlaveGain=1;
ch1->BacklashMode=BACKLASH_OFF;
ch1->BacklashAmount=0;
ch1->BacklashRate=0;
ch1->invDistPerCycle=1;
ch1->Lead=0;
ch1->MaxFollowingError=5000;
ch1->StepperAmplitude=250;
ch1->iir[0].B0=1;
ch1->iir[0].B1=0;
ch1->iir[0].B2=0;
ch1->iir[0].A1=0;
ch1->iir[0].A2=0;
ch1->iir[1].B0=1;
ch1->iir[1].B1=0;
ch1->iir[1].B2=0;
ch1->iir[1].A1=0;
ch1->iir[1].A2=0;
ch1->iir[2].B0=1;
ch1->iir[2].B1=0;
ch1->iir[2].B2=0;
ch1->iir[2].A1=0;
ch1->iir[2].A2=0;
// SPINDLE / A axis
ch2->InputMode=ENCODER_MODE;
ch2->OutputMode=DAC_SERVO_MODE;
ch2->Vel= 200000; // 1500rpm = 200000 counts per second
ch2->Accel=300000; // 2 second to 1500 rpm = 100000 CPS
ch2->Jerk= 300000;
ch2->P=20;
ch2->I=0;
ch2->D=50;
ch2->FFAccel=0;
ch2->FFVel=0;
ch2->MaxI=200;
ch2->MaxErr=1e+06;
ch2->MaxOutput=2000;
ch2->DeadBandGain=1;
ch2->DeadBandRange=0;
ch2->InputChan0=2;
ch2->InputChan1=0;
ch2->OutputChan0=2;
ch2->OutputChan1=0;
ch2->MasterAxis=-1;
ch2->LimitSwitchOptions=0x100;
ch2->LimitSwitchNegBit=0;
ch2->LimitSwitchPosBit=0;
ch2->SoftLimitPos=1e+30;
ch2->SoftLimitNeg=-1e+30;
ch2->InputGain0=-1;
ch2->InputGain1=1;
ch2->InputOffset0=0;
ch2->InputOffset1=0;
ch2->OutputGain=1;
ch2->OutputOffset=0;
ch2->SlaveGain=1;
ch2->BacklashMode=BACKLASH_OFF;
ch2->BacklashAmount=0;
ch2->BacklashRate=0;
ch2->invDistPerCycle=1;
ch2->Lead=0;
ch2->MaxFollowingError=100000;
ch2->StepperAmplitude=20;
ch2->iir[0].B0=1;
ch2->iir[0].B1=0;
ch2->iir[0].B2=0;
ch2->iir[0].A1=0;
ch2->iir[0].A2=0;
ch2->iir[1].B0=1;
ch2->iir[1].B1=0;
ch2->iir[1].B2=0;
ch2->iir[1].A1=0;
ch2->iir[1].A2=0;
ch2->iir[2].B0=1;
ch2->iir[2].B1=0;
ch2->iir[2].B2=0;
ch2->iir[2].A1=0;
ch2->iir[2].A2=0;
EnableAxis(0);
EnableAxis(1);
EnableAxis(2);
DefineCoordSystem(0,-1,1,-1);
}
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 7:57 pm
by TomKerekes
What kind of spindle Drive do you have? Torque? Velocity?
the spindle ramped up the DAC and it responded pretty nice
to what DAC values?
now i run a simple program with light cuts and the spindle will start running off and react terribly
Could you be more specific?
now i run a simple program with light cuts and the spindle will start running off and react terribly
Maybe this requires higher torque and/or more sudden torque demands?
One possibility is the Servo is tuned in a way to not to be cable to keep up, so lags behind, then overshoots when it is able to catch up. A simple way to check for this is to set the max following error to a smaller value (ie. 500) then if it lags behind the axis will trigger a following error and disable so you will be aware the axis isn't able to keep up. Its a good idea to have a small max following error on all axes anyways so if anything unusual happens the axis will disable.
Otherwise you might use a data capture program like shown below to observe exactly what is happening. Afterwards the data file can be inspected or plotted with some application like Excel. This Program can be assigned to an MCode (Execute - no wait) to be triggered in the GCode where interested to observe.
Code: Select all
#include "KMotionDef.h"
#define N 5000
main()
{
int i=0,k;
double T0,*p=gather_buffer;
T0 = Time_sec();
// Capture Data
for (i=0; i<N; i++)
{
for (k=0; k<5; k++) WaitNextTimeSlice(); // 5 * 180us = 900us x 5000 = 4.5sec
*p++ = Time_sec() - T0;
*p++ = ch2->Dest;
*p++ = ch2->Position;
*p++ = ch2->Output;
}
printf("Capture Complete - writing...\n");
FILE *f=fopen("C:\\temp\\kflopdata.txt","wt");
fprintf(f,"Time,Dest,Pos,Out\n");
p=gather_buffer;
for (i=0; i<N; i++)
{
// round times to neaarest servo tick
p[0] = ((int)(p[0]/TIMEBASE + 0.5))*TIMEBASE;
fprintf(f,"%16.9f,%16.6f,%16.6f,%16.6f\n",p[0],p[1],p[2],p[3]);
p += 4;
}
fclose(f);
}
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 8:19 pm
by turbothis
1 should be torque drive i believe
"Advance Motion Controls 30-125VAC Brush Type PWM Servo Amplifier 16A20ACT"
2 when i give it a lot of bolt ramming load it will DAC up to about 7 volt output
3
Code: Select all
G18 G20 G80 G90
G95
S1000 M04
G04P1
G01 X3.0 Z0.5 F0.010
G00 X1.605 Z0.2
G01 X1.5851 Z0.2
X1.5851 Z-1.6
G00 X1.9386 Z-1.2465
X1.9386 Z0.2
G01 X1.5652 Z0.2
X1.5652 Z-1.6
G00 X1.9187 Z-1.2465
X1.9187 Z0.2
G01 X1.5453 Z0.2
X1.5453 Z-1.6
G00 X1.8988 Z-1.2465
X1.8988 Z0.2
G01 X1.5254 Z0.2
X1.5254 Z-1.6
G00 X1.8789 Z-1.2465
X1.8789 Z0.2
G01 X1.5055 Z0.2
X1.5055 Z-1.6
G00 X1.859 Z-1.2465
X1.859 Z0.2
G01 X1.4855 Z0.2
X1.4855 Z-1.6
G00 X1.8391 Z-1.2465
X1.8391 Z0.2
G01 X1.4656 Z0.2
X1.4656 Z-1.6
G00 X1.8192 Z-1.2465
X1.8192 Z0.2
G01 X1.4457 Z0.2
X1.4457 Z-1.6
G00 X1.7993 Z-1.2465
X1.7993 Z0.2
G01 X1.4258 Z0.2
X1.4258 Z-1.6
G00 X1.7794 Z-1.2465
X1.7794 Z0.2
G01 X1.4059 Z0.2
X1.4059 Z-1.6
G00 X1.7595 Z-1.2465
X1.7595 Z0.2
G01 X1.386 Z0.2
X1.386 Z-1.6
G00 X1.7395 Z-1.2465
X1.7395 Z0.2
G01 X1.3661 Z0.2
X1.3661 Z-1.6
G00 X1.7196 Z-1.2465
X1.7196 Z0.2
G01 X1.3462 Z0.2
X1.3462 Z-1.6
G00 X1.6997 Z-1.2465
X1.6997 Z0.2
G01 X1.3263 Z0.2
X1.3263 Z-1.6
G00 X1.6798 Z-1.2465
X1.6798 Z0.2
G01 X1.3063 Z0.2
X1.3063 Z-1.6
G00 X1.6599 Z-1.2465
X1.6599 Z0.2
G01 X1.2864 Z0.2
X1.2864 Z-1.6
G00 X1.64 Z-1.2465
X1.64 Z0.2
G01 X1.2665 Z0.2
X1.2665 Z-1.6
G00 X1.6201 Z-1.2465
X1.6201 Z0.2
G01 X1.2466 Z0.2
X1.2466 Z-1.6
G00 X1.6002 Z-1.2465
X1.6002 Z0.2
G01 X1.2267 Z0.2
X1.2267 Z-1.6
G00 X1.5803 Z-1.2465
X1.5803 Z0.2
G01 X1.2068 Z0.2
X1.2068 Z-1.6
G00 X1.5603 Z-1.2465
X1.5603 Z0.2
G01 X1.1869 Z0.2
X1.1869 Z-1.6
G00 X1.5404 Z-1.2465
X1.5404 Z0.2
G01 X1.167 Z0.2
X1.167 Z-1.6
G00 X1.5205 Z-1.2465
X1.5205 Z0.2
G01 X1.1471 Z0.2
X1.1471 Z-1.6
G00 X1.5006 Z-1.2465
X1.5006 Z0.2
G01 X1.1271 Z0.2
X1.1271 Z-1.6
G00 X1.4807 Z-1.2465
X1.4807 Z0.2
G01 X1.1072 Z0.2
X1.1072 Z-1.6
G00 X1.4608 Z-1.2465
X1.4608 Z0.2
G01 X1.0873 Z0.2
X1.0873 Z-1.6
G00 X1.4409 Z-1.2465
X1.4409 Z0.2
G01 X1.0674 Z0.2
X1.0674 Z-1.6
G00 X1.421 Z-1.2465
X1.421 Z0.2
G01 X1.0475 Z0.2
X1.0475 Z-1.6
G00 X1.4011 Z-1.2465
X1.4011 Z0.2
G01 X1.0276 Z0.2
X1.0276 Z-1.6
G00 X1.3811 Z-1.2465
X1.3811 Z0.2
G01 X1.0077 Z0.2
X1.0077 Z-1.6
G00 X1.3612 Z-1.2465
X1.3612 Z0.2
G01 X0.9878 Z0.2
X0.9878 Z-1.6
G00 X1.3413 Z-1.2465
X1.3413 Z0.2
G01 X0.9679 Z0.2
X0.9679 Z-1.6
G00 X1.3214 Z-1.2465
X1.3214 Z0.2
G01 X0.948 Z0.2
X0.948 Z-1.6
G00 X1.3015 Z-1.2465
X1.3015 Z0.2
G01 X0.928 Z0.2
X0.928 Z-1.6
G00 X1.2816 Z-1.2465
X1.2816 Z0.2
G01 X0.9081 Z0.2
X0.9081 Z-1.6
G00 X1.2617 Z-1.2465
X1.2617 Z0.2
G01 X0.8882 Z0.2
X0.8882 Z-1.6
G00 X1.2418 Z-1.2465
X1.2418 Z0.2
G01 X0.8683 Z0.2
X0.8683 Z-1.6
G00 X1.2219 Z-1.2465
X1.2219 Z0.2
G01 X0.8484 Z0.2
X0.8484 Z-1.6
G00 X1.202 Z-1.2465
X1.202 Z0.2
G01 X0.8285 Z0.2
X0.8285 Z-1.6
G00 X1.182 Z-1.2465
X1.182 Z0.2
G01 X0.8086 Z0.2
X0.8086 Z-1.6
G00 X1.1621 Z-1.2465
X1.1621 Z0.2
G01 X0.7887 Z0.2
X0.7887 Z-1.6
G00 X1.1422 Z-1.2465
X1.1422 Z0.2
G01 X0.7688 Z0.2
X0.7688 Z-1.6
G00 X1.1223 Z-1.2465
X1.1223 Z0.2
G01 X0.7488 Z0.2
X0.7488 Z-1.6
G00 X1.1024 Z-1.2465
X1.1024 Z0.2
G01 X0.7289 Z0.2
X0.7289 Z-1.6
G00 X1.0825 Z-1.2465
X1.0825 Z0.2
G01 X0.709 Z0.2
X0.709 Z-1.6
G00 X1.0626 Z-1.2465
X1.0626 Z0.2
G01 X0.6891 Z0.2
X0.6891 Z-1.6
G00 X1.0427 Z-1.2465
X1.0427 Z0.2
G01 X0.6692 Z0.2
X0.6692 Z-1.6
G00 X1.0228 Z-1.2465
X1.0228 Z0.2
G01 X0.6493 Z0.2
X0.6493 Z-1.6
G00 X1.0028 Z-1.2465
X1.0028 Z0.2
G01 X0.6294 Z0.2
X0.6294 Z-1.6
G00 X0.9829 Z-1.2465
X0.9829 Z0.2
G01 X0.6095 Z0.2
X0.6095 Z-1.6
G00 X0.963 Z-1.2465
X0.963 Z0.2
G01 X0.5896 Z0.2
X0.5896 Z-1.6
G00 X0.9431 Z-1.2465
X0.9431 Z0.2
G01 X0.5696 Z0.2
X0.5696 Z-1.6
G00 X0.9232 Z-1.2465
X0.9232 Z0.2
G01 X0.5497 Z0.2
X0.5497 Z-1.6
G00 X0.9033 Z-1.2465
X0.9033 Z0.2
G01 X0.5298 Z0.2
X0.5298 Z-1.6
G00 X0.8834 Z-1.2465
X0.8834 Z0.2
G01 X0.5099 Z0.2
X0.5099 Z-1.6
G00 X0.8635 Z-1.2465
X0.8635 Z0.2
G01 X0.49 Z0.2
X0.49 Z-1.6
G00 X0.8436 Z-1.2465
X0.8436 Z0.2
X1.605 Z0.2
X3.0 Z1.0
M05 M09
M30
4 the program for the cuts is very gentle. way less impact as bolt ramming demo
"One possibility is the Servo is tuned in a way to not to be cable to keep up, so lags behind, then overshoots when it is able to catch up."
this describes it pretty good
i think ill try crazy slow acc and jerk to see if that calms it down
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 8:29 pm
by turbothis
is there any difference in the spindle performance between the G code program and just turning on the spindle by the CCW button?
my spindle jog below
Code: Select all
#include "KMotionDef.h"
#include "MySpindleDefs.h"
int *css_mode = &persist.UserData[PC_COMM_CSS_MODE]; // Mode 1=Normal RPM mode. 2=CSS
// desired speed is passed from KMotionCNC in variable KMVAR
// save in user variable STATEVAR whether it was off, CW, or CCW (0,1,-1)
// save in user variable SPEEDVAR the last desired speed
main()
{
float speed = *(float *)&persist.UserData[KMVAR]; // value stored is actually a float
int LastState = persist.UserData[STATEVAR]; // get last state
persist.UserData[SPEEDVAR] = persist.UserData[KMVAR]; // Always save the last desired speed
if (LastState==0 || *css_mode == 2)
{
// if spindle is off (or CSS mode) and User Changes the speed
// just save the desired speed
return 0;
}
// spindle is already on, so ramp to new speed
if (USE_POS_NEG_VOLTAGE)
Jog(SPINDLEAXIS,speed * FACTOR * LastState);
else
Jog(SPINDLEAXIS,speed * FACTOR);
printf("Jogging Spindle %f counts/sec\n",speed * FACTOR);
}
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 8:45 pm
by TomKerekes
i think ill try crazy slow acc and jerk to see if that calms it down
That should have no effect as the speed should be constant with no acceleration or Jerk needed.
is there any difference in the spindle performance between the G code program and just turning on the spindle by the CCW button?
There shouldn't be any difference. Unless you are in CSS mode (G96). In that case the speed will vary dependent on radius (X). But I don't see any G96 in the GCode. You might add a G97 to be sure the Spindle is in RPM mode.
You might also try running the GCode without any stock present (Air run) so there will be no load on the Spindle to see what happens.
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 9:09 pm
by turbothis
boy it did have trouble just cutting air!
what to look at now?
i lowered the following error to 5000 and it ...
"Following Error Disabled Axis:2"
this is a brushed DC motor so its not slipping or phasing out right? like a brushless could?
Re: more spindle servo tuning questions
Posted: Fri Jun 28, 2024 11:13 pm
by TomKerekes
boy it did have trouble just cutting air!
That simplifies things as it has nothing to do with load.
i lowered the following error to 5000 and it ...
"Following Error Disabled Axis:2"
That's a large error to be having. With an error of 100-150 the output should be saturated at 10V (with P Gain of 20). When does the error happen?
What gets printed to the console? The speed should only be set once at the beginning of the GCode.
You might single step through the GCode.
Maybe you have some wiring error such as a missing GND such that the X Z DACs have an effect on the Spindle?
Re: more spindle servo tuning questions
Posted: Sat Jun 29, 2024 12:16 am
by turbothis
ok, i lowered the error to 150 and slowed the accel and jerk to
Code: Select all
ch2->Vel= 200000; // 1500rpm = 200000 counts per second
ch2->Accel=50000; // 2 second to 1500 rpm = 100000 CPS
ch2->Jerk= 100000;
ch2->P=20;
ch2->I=0;
ch2->D=50;
and runs stable but is kinda wimpy spindle performance
the spindle will power up to 1500 rpm in about a second with some larger accel and jerk values. seems very powerful to me!
it will also not over shoot any rpm revving up, just the deceleration has mega trouble
how fast would be reasonable to slow it back to zero?
can i run that logging program to see how fast in kill mode the spindle can get up to speed and see how far behind the position gets at this?
Re: more spindle servo tuning questions
Posted: Sat Jun 29, 2024 8:30 pm
by TomKerekes
Hi Turbothis,
Your responses seem to jump around from one post to the next without any closure on things so I'm having a hard time following. It seems the original problem was starting up the spindle and not while running GCode.
You might start over and tune the axis using the Step Response Screen to see what ranges the Spindle is capable of.
Re: more spindle servo tuning questions
Posted: Sun Jun 30, 2024 7:39 pm
by turbothis
ya i am a mess on this
at one point i had it tuned to spin up and down on the RPM slider very aggressively, i mean respect!
made some cuts and threaded some stuff no problem
then the event where it all kind of went sideways on me
working back up to useful performance since then....
i even posted the settings which i have revisited a bunch and i cant get the spindle stable anywhere
i am feeling like one of my CW/CCW, spindle jog or something like that is off, but i dont know.
in all my other axis i can tune them in a couple minutes.
so on the step/response screen, a small 3 second move is accurate up to 1500rpm and 100 pounds of rotational mass?