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problem about linear move


twathit
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Hi,

I attached my setup and motion program below.I am using position compare function, the motion is very simple, just a straight line from one point to another point, but need it move slow, and the position compare woks fine,but I found the move isn’t smooth, I mean, because the motor moves very slow, I can see it moves a little, then stop, then moves a little, then stop…till it reach the position, like it was joggling. When I use rapid move,it move smoothly, but the speed is too fast.I don’t know if I need more setup about linear move.

Here is my setup:

Motor[1].ServoCtrl=1

Motor[2].ServoCtrl=1

Motor[3].ServoCtrl=1

Motor[4].ServoCtrl=1

 

// Disable overtravel limit inputs when set to 0

// May be needed if there are no physical switches present

//Motor[1].pLimits=Gate1[6].Chan[0].Status.a

//Motor[2].pLimits=Gate1[6].Chan[1].Status.a

//Motor[3].pLimits=Gate1[6].Chan[2].Status.a

//Motor[4].pLimits=Gate1[6].Chan[3].Status.a

 

// Disable amplifier enable output

// May be needed if channel is also connected to real amplifier

Motor[1].pAmpEnable=0

Motor[2].pAmpEnable=0

Motor[3].pAmpEnable=0

Motor[4].pAmpEnable=0

 

// Disable amplifier fault input

// May be needed if channel is also connected to real amplifier

Motor[1].pAmpFault=0

Motor[2].pAmpFault=0

Motor[3].pAmpFault=0

Motor[4].pAmpFault=0

 

// Set derivative gain term in servo loop to zero

// This is a Type 1 servo (single integration); does not need Kvfb

Motor[1].Servo.Kvfb=0

Motor[2].Servo.Kvfb=0

Motor[3].Servo.Kvfb=0

Motor[4].Servo.Kvfb=0

 

// Lower proportional gain term from default

Motor[1].Servo.Kp=40

Motor[2].Servo.Kp=40

Motor[3].Servo.Kp=40

Motor[4].Servo.Kp=40

 

// Add Kvff and Ki

Motor[1].Servo.Kvff=40

Motor[2].Servo.Kvff=40

Motor[3].Servo.Kvff=40

Motor[4].Servo.Kvff=40

 

Motor[1].Servo.Ki=0.001

Motor[2].Servo.Ki=0.001

Motor[3].Servo.Ki=0.001

Motor[4].Servo.Ki=0.001

 

// Deactivate commutation for all motors

Motor[0].PhaseCtrl=0 // No phase commutation active

Motor[2].PhaseCtrl=0 // No phase commutation active

Motor[3].PhaseCtrl=0 // No phase commutation active

Motor[4].PhaseCtrl=0 // No phase commutation active

 

Gate1[6].Chan[0].OutputMode=3 //CH1A and CH1B ouputs will be DAC and CH1C output will be PFM

Gate1[6].Chan[1].OutputMode=3 //CH2A and CH2B ouputs will be DAC and CH2C output will be PFM

Gate1[6].Chan[2].OutputMode=3 //CH3A and CH3B ouputs will be DAC and CH3C output will be PFM

Gate1[6].Chan[3].OutputMode=3 //CH4A and CH4B ouputs will be DAC and CH4C output will be PFM

 

Gate1[6].Chan[0].EncCtrl = 8 //Simulated feedback for channel 1

Gate1[6].Chan[1].EncCtrl = 8 //Simulated feedback for channel 2

Gate1[6].Chan[2].EncCtrl = 8 //Simulated feedback for channel 3

Gate1[6].Chan[3].EncCtrl = 8 //Simulated feedback for channel 4

 

// Create encoder conversion table entries for all motors

EncTable[1].Type=3

EncTable[1].pEnc=Gate1[6].Chan[2].ServoCapt.a

EncTable[1].pEnc1=Gate1[6].Chan[2].TimeBetweenCts.a

EncTable[1].index1=0

EncTable[1].index2=0

EncTable[1].index3=0

EncTable[1].index4=0

EncTable[1].MaxDelta=0

EncTable[1].ScaleFactor=1/512

 

EncTable[2].Type=3

EncTable[2].pEnc=Gate1[6].Chan[2].ServoCapt.a

EncTable[2].pEnc1=Gate1[6].Chan[2].TimeBetweenCts.a

EncTable[2].index1=0

EncTable[2].index2=0

EncTable[2].index3=0

EncTable[2].index4=0

EncTable[2].MaxDelta=0

EncTable[2].ScaleFactor=1/512

 

EncTable[3].Type=3

EncTable[3].pEnc=Gate1[6].Chan[2].ServoCapt.a

EncTable[3].pEnc1=Gate1[6].Chan[2].TimeBetweenCts.a

EncTable[3].index1=0

EncTable[3].index2=0

EncTable[3].index3=0

EncTable[3].index4=0

EncTable[3].MaxDelta=0

EncTable[3].ScaleFactor=1/512

 

EncTable[4].Type=3

EncTable[4].pEnc=Gate1[6].Chan[2].ServoCapt.a

EncTable[4].pEnc1=Gate1[6].Chan[2].TimeBetweenCts.a

EncTable[4].index1=0

EncTable[4].index2=0

EncTable[4].index3=0

EncTable[4].index4=0

EncTable[4].MaxDelta=0

EncTable[4].ScaleFactor=1/512

 

// Point motors to encoder conversion table entries

Motor[1].pEnc=EncTable[1].a

Motor[2].pEnc=EncTable[2].a

Motor[3].pEnc=EncTable[3].a

Motor[4].pEnc=EncTable[4].a

 

Motor[1].pEnc2=EncTable[1].a

Motor[2].pEnc2=EncTable[2].a

Motor[3].pEnc2=EncTable[3].a

Motor[4].pEnc2=EncTable[4].a

 

Motor[1].pDac=Acc24E2S[6].Chan[0].Pwm[2].a //Command output to CH1A address (default address + 2) for Stepper

Motor[2].pDac=Acc24E2S[6].Chan[1].Pwm[2].a //Command output to CH2A address (default address + 2) for Stepper

Motor[3].pDac=Acc24E2S[6].Chan[2].Pwm[2].a //Command output to CH3C address (default address + 2) for Stepper

Motor[4].pDac=Acc24E2S[6].Chan[3].Pwm[2].a //Command output to CH4C address (default address + 2) for Stepper

 

Motor[1].JogSpeed=5

Motor[2].JogSpeed=5

Motor[3].JogSpeed=5

Motor[4].JogSpeed=5

 

//Gate1[6].Chan[0].Pfm=5000

//Gate1[6].Chan[1].Pfm=5000

//Gate1[6].Chan[2].Pfm=5000

//Gate1[6].Chan[3].Pfm=5000

 

Gate1[6].Chan[0].CompA=400

Gate1[6].Chan[1].CompA=400

Gate1[6].Chan[2].CompA=1

Gate1[6].Chan[3].CompA=400

 

Gate1[6].Chan[0].CompB=-400

Gate1[6].Chan[1].CompB=-400

Gate1[6].Chan[2].CompB=-1

Gate1[6].Chan[3].CompB=-400

 

Gate1[6].Chan[0].CompAdd=1600

Gate1[6].Chan[1].CompAdd=1600

Gate1[6].Chan[2].CompAdd=4

Gate1[6].Chan[3].CompAdd=1600

 

Gate1[6].Chan[0].EquWrite=3

Gate1[6].Chan[1].EquWrite=3

Gate1[6].Chan[2].EquWrite=3

Gate1[6].Chan[3].EquWrite=3

 

The motion program is:

open prog 1 // Open buffer for entry

linear; // Linear interpolation move mode

abs; // Absolute move mode

ta500; // 1/2-second accel/decel time

ts0; // No S-curve accel/decel time

f5; // Speed of 500 axis units per time unit

X500; // Move X-axis to position of 900 units

dwell2000;

close // Close buffer, end program entry

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It would appear that your tuning (PID) parameters are somewhat arbitrary. These should be arrived at by following the tuning procedure as outlined in the Users Manual and software.

I generally skip the auto tune and tune manually (using the tools provided). It works very well. Other people use the auto tune as a starting point before doing a manual tune.

Properly done, I would compare the results against any other system.

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You have a command of "f5" in your program, which is for 5 axis units per time unit, not 500!

 

You don't show what your axis unit is (#1->???X) or what your time unit is (default is seconds).

 

I suspect you are commanding a VERY slow move, and the physical axis is breaking in and out of static friction.

 

Add a "Gather.Enable=2" to your program before the move (to enable gathering), and a "Gather.Enable=0" after the dwell (to disable). Make sure in the Plot utility that you are gathering both command and actual position, then plot command and actual velocity. I suspect that you will see a nice smooth command velocity profile, but a very rough actual velocity profile. This would indicate a tuning problem, as mbalentine suggests.

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