Dificulties following a prescribed velocity profile

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Emanuel Camacho
Posts: 2
Joined: Thu Nov 21, 2019 8:36 am

Dificulties following a prescribed velocity profile

Post by Emanuel Camacho » Fri Nov 22, 2019 11:40 am

Good day.

I'm using the motor (Item # PKE543AC, 1.65 in. (42 mm) 5-Phase Stepper Motor (AC Input)) and I want to follow a specific velocity profile to study the pitching motion of a wing. The desired velocity profile is shown in red in the file attached. For the tested condition, the motion's amplitude and velocity are 28 steps and 222 steps/s, respectively. The problem is that the motor follows approximately the line in green which made me think that it was due to the motor starting speed. The same problem was not visible for higher amplitudes (although it can be present). I concluded that the starting speed played an important role since when I changed it to around 20Hz (default was 500Hz), the motor followed approximately the velocity profiled described. Setting the starting speed to 0Hz did not work since it added a motion delay at the beginning. What should I do to find the desired starting speed, or it there any other way to follow the prescribed motion?

Any input would be very much appreciated.

Best regards,
Emanuel Camacho
Attachments
bitmap.png
bitmap.png (12.03 KiB) Viewed 264 times

om_tech_support_KR
Posts: 67
Joined: Thu Jan 11, 2018 3:03 pm

Re: Dificulties following a prescribed velocity profile

Post by om_tech_support_KR » Fri Nov 22, 2019 2:41 pm

Hi Emanuel,

If using the motor with the pulse input type driver then the programming would be done on the controller and you would have to set the acceleration and deceleration rates from there. If using the driver with built in controller you can set these with either the MEXE02 software or RS-485 Modbus RTU communication.

Emanuel Camacho
Posts: 2
Joined: Thu Nov 21, 2019 8:36 am

Re: Dificulties following a prescribed velocity profile

Post by Emanuel Camacho » Mon Nov 25, 2019 6:36 am

Good day.

Yes, I am using the driver with a built-in controller and the acceleration/deceleration is being modified with the MEXE02 software. The problem is that I cannot follow a prescribed motion (illustrated in the attachment (velocity_profile.jpg)).
As seen in the picture, the velocity value at the beginning much start at zero, so I changed the Starting Speed parameter to 0Hz. However the motion is what is shown in 0Hz.jpg image (200 ms regions with 0r/min). Setting the Starting Speed to 500Hz (default) gives the results shown in 500Hz.jpg. My problem is that the motor should start with zero velocity at immediately start accelerating. What should I do?

Best regards,
Emanuel Camacho
Attachments
500Hz.jpg
500Hz.jpg (187.46 KiB) Viewed 221 times
0Hz.jpg
0Hz.jpg (179.88 KiB) Viewed 221 times
velocity_profile.jpg
velocity_profile.jpg (36.29 KiB) Viewed 221 times

om_tech_support_KR
Posts: 67
Joined: Thu Jan 11, 2018 3:03 pm

Re: Dificulties following a prescribed velocity profile

Post by om_tech_support_KR » Mon Nov 25, 2019 2:32 pm

Hi Emanuel,

Does decreasing the acceleration and deceleration rate help with the delay when starting speed is 0Hz? Does increasing the starting speed get rid of this delay? You can increase the starting speed in increments of 1Hz.

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