Stepper motor #1 axis

[DrillBitBob]

In step response the motor runs smoothly. When you move it with the control panel arrows or the gamepad it moves but with alot of growling and some hesitation after it moves 6"either direction. Ideas or direct me to a post that addresses this problem. Thank you

[TomKerekes]

Hi Bob,

Please post your initialization program. What is your Jog Speed? How large of a move are you testing in the Step Response Screen?

[DrillBitBob]

// Defines axis 0, 1, 2 as simple step dir TTL outputs for KSTEP
// enables them
// sets them as an xyz coordinate system for GCode

int main()
{
double T0, LastX=0, LastY=0, LastZ=0, Tau;

KStepPresent=TRUE; // enable KSTEP input multiplexing
FPGA(KAN_TRIG_REG)=4; // Mux PWM0 to JP7 Pin5 IO 44 for KSTEP

FPGA(STEP_PULSE_LENGTH_ADD) = 63 + 0x80; // set polarity and pulse length to 4us

ClearStopImmediately();

ch0->InputMode=NO_INPUT_MODE;
ch0->OutputMode=STEP_DIR_MODE;
ch0->Vel=40000;
ch0->Accel=200000;
ch0->Jerk=4e+06;
ch0->P=0;
ch0->I=0.01;
ch0->D=0;
ch0->FFAccel=0;
ch0->FFVel=0;
ch0->MaxI=200;
ch0->MaxErr=1e+06;
ch0->MaxOutput=200;
ch0->DeadBandGain=1;
ch0->DeadBandRange=0;
ch0->InputChan0=0;
ch0->InputChan1=0;
ch0->OutputChan0=8;
ch0->OutputChan1=0;
ch0->MasterAxis=-1;
ch0->LimitSwitchOptions=0x100;
ch0->LimitSwitchNegBit=0;
ch0->LimitSwitchPosBit=0;
ch0->SoftLimitPos=1e+30;
ch0->SoftLimitNeg=-1e+30;
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=20;

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=0.000769;
ch0->iir[2].B1=0.001538;
ch0->iir[2].B2=0.000769;
ch0->iir[2].A1=1.92076;
ch0->iir[2].A2=-0.923833;
EnableAxisDest(0,0);

ch1->InputMode=NO_INPUT_MODE;
ch1->OutputMode=STEP_DIR_MODE;
ch1->Vel=40000;
ch1->Accel=200000;
ch1->Jerk=4e+06;
ch1->P=0;
ch1->I=0.01;
ch1->D=0;
ch1->FFAccel=0;
ch1->FFVel=0;
ch1->MaxI=200;
ch1->MaxErr=1e+06;
ch1->MaxOutput=200;
ch1->DeadBandGain=1;
ch1->DeadBandRange=0;
ch1->InputChan0=0;
ch1->InputChan1=0;
ch1->OutputChan0=9;
ch1->OutputChan1=0;
ch1->MasterAxis=-1;
ch1->LimitSwitchOptions=0x100;
ch1->LimitSwitchNegBit=0;
ch1->LimitSwitchPosBit=0;
ch1->SoftLimitPos=1e+30;
ch1->SoftLimitNeg=-1e+30;
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=1000000000;
ch1->StepperAmplitude=20;

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=0.000769;
ch1->iir[2].B1=0.001538;
ch1->iir[2].B2=0.000769;
ch1->iir[2].A1=1.92076;
ch1->iir[2].A2=-0.923833;
EnableAxisDest(1,0);

ch2->InputMode=NO_INPUT_MODE;
ch2->OutputMode=STEP_DIR_MODE;
ch2->Vel=40000;
ch2->Accel=200000;
ch2->Jerk=4e+06;
ch2->P=0;
ch2->I=0.01;
ch2->D=0;
ch2->FFAccel=0;
ch2->FFVel=0;
ch2->MaxI=200;
ch2->MaxErr=1e+06;
ch2->MaxOutput=200;
ch2->DeadBandGain=1;
ch2->DeadBandRange=0;
ch2->InputChan0=0;
ch2->InputChan1=0;
ch2->OutputChan0=10;
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=1000000000;
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;
EnableAxisDest(2,0);

DefineCoordSystem(0,2,-1,-1);

SetBitDirection(45,1); // set Enable Signal as Output
SetBit(45); // Enable the amplifiers

// Add a small amount of Coordinated Motion Path smoothing if desired
// Tau = 0.001; // seconds for Low Pass Filter Time Constant
// KLP = exp(-TIMEBASE/Tau);
KLP=0; // force to 0 to disable
// printf("Tau=%f KLP=%f\n",Tau,KLP);



for (;;)
{
WaitNextTimeSlice();
SetStateBit(46, ch0->Dest <= 1000.0);
SetStateBit(47, ch0->Dest >= -1000.0);
if (ch0->Enable && !ch1->Enable) DisableAxis(0);
if (ch1->Enable && !ch0->Enable) DisableAxis(1);
}



#if 0
for (;;) // loop forever
{
WaitNextTimeSlice();

// Service Amplifier disable after no activity for a while
if (ch0->Dest != LastX || ch1->Dest != LastY || ch2->Dest != LastZ)
{
// we moved - enable KStep Amplifers
SetBit(45);
T0 = Time_sec(); // record the time and position of last motion
LastX=ch0->Dest;
LastY=ch1->Dest;
LastZ=ch2->Dest;
}
else
{
if (Time_sec() > T0 + 10.0) ClearBit(45);
}
}
#endif
return 0;
}
Itook screenshot of the step response but don't know how insert them.

[DrillBitBob]

Step response

Step response screenshot

[TomKerekes]

Hi Bob,

I don't see anything unusual. Post your KMotionCNC | Tool Setup | Trajectory Planner Screen so we can see the axis resolution and Jog Speeds.

Please describe the behavior more clearly. Is the problem a position related thing. ie any moves beyond 6 inches cause the "growl"? Or is it "growling" whenever moving 6 inches all at once?

What is the range of travel of your system? Could it be mechanically binding?

[DrillBitBob]

trajectary planner

I changed the jog to .75 on the y axis and the growling disappeared. Not sure how that is going reflect maximum travel speed when I run a program.
I will continue to for mechanical binding but since it works great in step response for moves of 10 inches +- . Thank you for all your help. Happy Holidays

[TomKerekes]

Hi Bob,

Sometimes a Stepper axis can have a resonance that is excited when moving at a particular speed. Higher or lower speed may not show any issue. You might try the Step Response Screen at a speed of 16238 steps/second which would be a speed of 1 inch/second to see it that speed is an issue.

Unfortunately a Milling machine should be able to move at all speeds without issue.

A test I like to do is to set the acceleration very very low. In this case the speed will gradually ramp up to test moving at all speeds.

Jog speeds have no effect while running a Job.

I see the Axis Parameter Speeds are limited to 10 inches/sec. That would be 162380 steps/sec. But you are only testing 40000 steps/sec in the Step Response Screen so maybe you should reduce those. This won't matter unless you command a Feedrate higher than the limits. Similarly Acceleration is set at 30 inches/sec2 but you only test 12.32 inches/sec2.

You might read this wiki article.

[DrillBitBob]

The problem could be a bad motor. Channel 1 is the master of Channel 3 that both drive the Y axis. I have removed the motors from the ball screws for easy visual aid. In step response channel 1 moves drives both 1 and 3 properly to my eye. In channel 3 the move drives only itself properly. I have downloaded the config data to both InitKSep3AxisSlave.c and InitKStep4Axis.c, saved it, compiled, downloaded it, and ran it. Only 4Axis addresses channel 3 which is currently loaded.When jogging the Y axes Motor 1 works properly Motor 3 attempts to turn but just gets maybe 1/4 turn.
To get the machine running 2 years ago my work around was to wire both to channel 1. It worked until this growling started which now I want to resolve this correctly. Any ideas why they work properly in step response yet not from jogging. Thank you

[Moray]

A simple test for the motor, is to swap it to a different driver.
If the problem moves with the motor, it's a motor issue. If the problem stays with the driver, it's a config/driver issue.

[DrillBitBob]

The motors are not the problem since the problem stayed with channel 3. Here's the latest Init file I compiled, downloaded and ran. I have another KStep board that I could try. It baffles me it works so well in step response and not from the display. Thank you again for all your help.