Servo Motor Position Drift After Continuous Cycles on Pick and Place Machine

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#1 21673404 13 Feb 2015 04:20

Ankim Tandon Ankim Tandon

Anonymous

Post #1
21673404 13 Feb 2015 04:20

Hello Friends,

I am facing problem on my servo position.

I have pick n place machine , where my pick n place position are servo motor position controlled.I am facing problem is after few continuous cycle the position is not the same.
For example my calibration position is 85mm but after continous cycle position is out to 95 mm.I have crossed check my PLC code there is no calculation mistake.

Once i have origin my servo position starts from 85mm but after few cycle it starts to drift again.

Is there a possiblity of Noise on Servo pulse train cable ?
Cable are twisted pair cables for servo to move ccw and cw direction.

Can someone help me how to reduce noise or what could be cause of noise.?

Appreciate some direction
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#2 21673405 18 Feb 2015 10:59

Rohit Dubla Rohit Dubla

Anonymous

Post #2
21673405 18 Feb 2015 10:59

I would look at what the feedback signal is when it starts to go out of specification. It could be temperature related...
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#3 21673406 25 Feb 2015 03:12

Frank Bushnell Frank Bushnell

Anonymous

Post #3
21673406 25 Feb 2015 03:12

Possibility: loose or worn position sensor in the servo.

Do you have a spare servo to replace the part and test it again ?
#4 21673407 27 Feb 2015 04:09

vikasbly44 vikasbly44

Anonymous

Post #4
21673407 27 Feb 2015 04:09

DEAR...

If you have a spare servo to replace.. if yes, then you can replace the part and test it ..again..

THANKX...
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#5 21673408 27 Feb 2015 10:07

Frank Bushnell Frank Bushnell

Anonymous

Post #5
21673408 27 Feb 2015 10:07

Hi there Vik,
Is it your intention to be sarcastic ? Most people here are trying to be helpful.
#6 21673409 01 Mar 2015 00:54

Ankim Tandon Ankim Tandon

Anonymous

Post #6
21673409 01 Mar 2015 00:54

Mr Rohit ,

Temperature on monitoring showed it is very stable and machine is in clean room enviornment.

The command pulse and received pulse on the servo drivor has differs....Looks like servo driver receiving pulse Cable (CCW/CW) has noise picking up from panel wiring.

I have added some ferrites and Isolated AC/DC wiring from eachother.

I will try to monitor it now...

Thank you,
Ankim
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#7 21673410 01 Mar 2015 00:57

Ankim Tandon Ankim Tandon

Anonymous

Post #7
21673410 01 Mar 2015 00:57

DEAR I am trying to find out root cause.....before i suspect its a servo driver or servo motor fault.
#8 21673411 01 Mar 2015 00:58

Ankim Tandon Ankim Tandon

Anonymous

Post #8
21673411 01 Mar 2015 00:58

Mr Frank,

My servo sequence is Position based and not sensor based.
#9 21673412 31 Dec 2015 09:51

Zachary Pick Zachary Pick

Anonymous

Post #9
21673412 31 Dec 2015 09:51

Ankim

Servos have position sensors (encoders) built in. What kind of actuator are you using? If the encoder of the servo is not damaged or loose, and if the actuator is a belt, is the belt slipping?
#10 21673413 02 Jan 2016 10:32

Justin Spencer Mamaradlo Justin Spencer Mama...

Anonymous

Post #10
21673413 02 Jan 2016 10:32

Hi there Ankim.

Though it has been 10 months, I would like to share my ideas on this problem.

I think you are having a problem with offset. Position controlled feedback systems are very vulnerable to this. I suggest using a PID controller. You just have to add a few resistors and capacitors here and there. The schem. can easily be googled.

If this doesn't work, then the problem may indeed lie in parts replacement.

Regards,
Justin
#11 21673414 03 Jan 2016 14:05

Sambath Kumar Sambath Kumar

Anonymous

Post #11
21673414 03 Jan 2016 14:05

Hi Ankim Tandon ,

I think this is a mechanical problem your arm mover will have a spring loaded
system which will help the arm to reach the zero level point after every forward
movement , may be the spring fixing is loose or tension of the spring is gone or
wrong mech fixing. the servo motor is driven usually by transistors some times
one of the power transistor or its driver transistor may be weak replace it.

pl review my rating.

V.Sambath kumar
#12 21673415 27 Jul 2020 01:48

Manoj Kumar Manoj Kumar

Anonymous

Post #12
21673415 27 Jul 2020 01:48

Dear.
I have also faced the same problem .Reason:1. Pulse train wiring interracted with ac power supply cables2. amplifier issue3. 99percent - noise from ac power suply in the panel Remedy : use noise filter between ac power supply.
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Topic summary

A pick and place machine using servo motor position control experiences position drift after continuous cycles, with calibrated positions shifting from 85mm to 95mm. The PLC code was verified with no errors. Potential causes discussed include noise interference on the servo pulse train cables (twisted pair for CCW/CW control), temperature effects, loose or worn position sensors (encoders), mechanical issues such as belt slipping or spring tension loss, and possible faults in servo driver transistors. Noise coupling from AC power supply cables into pulse wiring was highlighted as a common issue, with recommendations to use ferrite beads, isolate AC/DC wiring, and install noise filters. Suggestions also included testing with a spare servo, monitoring feedback signals, and implementing PID control with additional resistors and capacitors to address offset errors in position feedback systems.
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Servo Motor Position Drift After Continuous Cycles on Pick and Place Machine

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