Experimental Physics and
Industrial Control System

On a related note, we asked the Pro-Dex engineers about the closed-loop correction for stepper motors in the MAXv controller the other day.  He said that if the MAXv is configured for position maintenance with an encoder and stepper motor then it does any required correction at the end of the move.  It does not do any corrections as the move is in progress. It is not clear if the EPICS driver supports this mode.  Most of the applications I know of are using the EPICS motor retries, and not the built-in controller correction.

I also don't know for sure how the XPS handles this.  My impression was that it was constantly correcting, and not just at the end of the move, but I am not certain.

Mark

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Pearson, Matthew R.
Sent: Wednesday, July 15, 2015 9:06 AM
To: Torsten Bögershausen
Cc: [email protected]; [email protected]
Subject: Re: Stepper Motor Controllers

>> 
>> Regarding closed loop mode:  While I can imagine circumstances where you might
>> want to disable it, I would think that any controller that supports an encoder
>> would also provide a closed loop mode.  Is that not so?  I would think there
>> would be little advantage to supporting an encoder if it couldn't be used
>> directly by the controller during movements (i.e. isn't this question the SAME
>> as "Does it support a position encoder"?)
> I think so.
> Some controllers should be able to make "smooth movements" towards the
> target position.
>> 

Just to clarify this point. The Parker 6K series does support encoders, but not closed loop control on stepper axes. It's only for feedback to the user. For some stages where the mechanics are poor, or we lose steps, we have to use the motor record retry capability. It's best to have the controller do the closed loop, so it can move to position, or fail, without having software logic on top.

Cheers,
Matt

Replies:

Re: Stepper Motor Controllers Mark Davis

References:

Stepper Motor Controllers Mark Davis

RE: Stepper Motor Controllers Mark Rivers

Re: Stepper Motor Controllers Mark Davis

Re: Stepper Motor Controllers Torsten Bögershausen

Re: Stepper Motor Controllers Pearson, Matthew R.

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