Servo Motor Position Control with PI Controller

Discuss Oriental Motor's new NX series servo motor series, or anything related to servo technology.
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Joined: Thu Sep 10, 2020 3:03 am

Servo Motor Position Control with PI Controller

Post by snantilg » Thu Sep 10, 2020 3:39 am

Hey Everyone!

This is my first post here. I have a problem concerning the position control of a 400W BLDC Motor. Attached you can find the Motor Datasheet. The Technical Manual of the controller is unfortunately too big to upload, but here is the link: ... hernetip/

The position control is really bad right now. It takes about 2s to get into the desired position and I would like it to be a lot faster (about 0.5s). The controller has a build in PI closed loop control. In Object 3210h (p. 197 in the manual) it is possible to set the Proportional Gain and the Integral Gain. The Preset values are: P = 00000800h and I = 00000000h. When playing around with the P-Gain the control barely changes. When I change the I-Gain even the slightest bit ( from 00000000h to 00000001h) the motor starts to oscillate around the desired location and never stops. When I increase the I-Gain above 1 the amplitude just becomes larger and at some value causes an error.
The motor load is a spherical mirror with a mass moment of inertia of about 15000kgmm^2. I could not find a way to tell the controller the load though and I am not sure if that matters.

I am writing my bachelorthesis in mechanical Engineering right now and this is the first time I am working with an electrical motor, so I am not very knowledgable in this subject.

Any help or ideas would be greatly appreciated!!
Thanks in advance

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Re: Servo Motor Position Control with PI Controller

Post by om_tech_support_KR » Thu Sep 10, 2020 7:42 am


Since this is not one of our products it would be best to contact Nanotec for setting of the parameters. For our servo motors you can manually set the gain tuning but we have different parameters to match to the load inertia to reduce hunting.

Gain.PNG (25.25 KiB) Viewed 305 times

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