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Commanded velocity fluctuation


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Firmware version:

Controller: CK3M

Servo update frequency 4KHz.


In my machine B axis is defined as

#5-> 1#5->5965233B

Coord[1].FRAxes = $1C0  //XYZ

I am commanding as per the following program.

G01 B0 F1000

dwell 500


dwell 500


When I plot graph for commanded velovity and acceleration, it shows velocity is oscillates after  acceleration is complete. Due to these fluctuations, acceleration feed forward is also fluctuating and creating noise in the motor.

Can you suggest what should the cause?




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  • 2 weeks later...
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I suspect a tuning issue, maybe needing less proportional or more derivative gain.  A plot file or screenshot of the tuning step move might be revealing.  I suggest sending to ODT-Support@omron.com.  

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  • 5 weeks later...

I have conducted following two test on other motor

1. When the acceleration is restricted to 60mm/sec^2, the commanded feed of 2000mm/min only reaches a maximum value of 1741mm/min with ripples.

2. However, If a feed of 1400mm/min is set instead, the velocity reaches the commanded value without any additional fluctuations.  

I could not understand why in case 1 motor does not reach to commanded feed.




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Try the "Why is my motor moving slowly?" by selecting "Troubleshooters" in the IDE "Delta Tau" tab.  
Depending on how the move is commanded, it might be something like Motor[x].MaxDac or Motor[x].MaxSpeed.

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If I increase the acceleration from 60mm/sec^2 to 100mm/sec^2, then it is able to reach to 2000mm/min ( I have set Coord[x].Ta=0 ,Coord[x].Td=0 ,Coord[x].Ts=0.02 with segmentation enabled). Acceleration is changed with Motor[x].InvaMax.  It looks like that some other parameter is limiting the maximum speed other then Motor[x].InvaMax.

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