Closed loop speed position problem

3 years 7 months ago #29532716 by Vatu
Hi,

I use SDC2160 in closed loop speed position mode. Each motor is controlled separately. PID used proportional gain only. Everything works fine until both motors get positive rotation. First motor starts pulsing in this case.

Any suggestions where is problem?

Thanks
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3 years 7 months ago #29532717 by blake
Hello sorry for the late response.

So when you run both motor channels independently they both operate smoothly, but one cogs when both motor channels are running at the same time?

Are you using the same motor on both motor channels? (two motors of the same model)

Please send me your configuration file. You can attach it here in .zip format or send it to me at This email address is being protected from spambots. You need JavaScript enabled to view it.

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3 years 7 months ago #29532718 by Vatu
Replied by Vatu on topic Closed loop speed position problem
Hello,

thanks for quick replay.
My previous observation has mistake. Both motors cogs when both motors run in positive direction at same time.
Yes I used identical motors, but first motor has about 1% less RPM without load.


Thanks


Ales Ruda
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3 years 7 months ago #29532719 by blake
Thank you for sending your configuration.

I see that you have the PPR for your encoders set to 3 PPR. That equates to 12 CPR (counts per revolution). Is this accurate? It is not impossible just not very typical, that is an extremely low resolution. To confirm the CPR of your encoder do the following:
  • Put motor channel in open loop.
  • Enable the encoder channel you are observing in the capture window of the Run tab
  • If counts are not at zero already, reset to zero by sending the command !C 0 from the console tab
  • Rotate the motor shaft by hand one full 360 degree revolution
  • The number than shows in the counts channel after one revolution is your CPR (counts per revolution)
  • The PPR (pulses per revolution) is one fourth of the counts per revolution. So if your counts is 1000 your PPR would be 250. This is the value that you save in the configuration tab

The second thing I would have you try is to see if the problem persists if you decrease your Proportional gain to a lower value.

Other than these things nothing sticks out to me as a cause for the issue. I am unable to replicate the symptoms you report on my side with two motors and my own SDC2160. If the problem persists after trying the above, then please download and install TeamViewer and contact me at This email address is being protected from spambots. You need JavaScript enabled to view it. so that we can schedule a remote session to observe together.

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3 years 7 months ago #29532720 by Vatu
Replied by Vatu on topic Closed loop speed position problem
PPR 3 is correct.
I tried to change proportional gain without success.
I tests different configurations and scenarios. If first motor is in open loop and second in close speed position loop then second motor cogs.
If second motor is in open loop and first in close speed position loop then no cogs.

Ales

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