Motion Control and Motor Drives

[WimK]

Hello,

At this moment I am using LabVIEW and NI-motion and I already have made some straight line moves. Now I am creating some contoured moves. I can read a pt-file in LabVIEW and run it.

Everything seems fine, but the start and stop of my movement is very ‘fast’ (jerk) and I like to smooth the start and stop a little.

I also have tried to use pvt-files, but I don’t get the velocity an acceleration right (The set velocity is ok at the end of a segment, but before that it has large overshoots)

I have redden that I cannot use the move constraints for the contoured moves that I am using for the straight line moves. (velocity, acceleration, deceleration, jerk) However, In Motion assistant is suggested that I can use those constraints (By enabling or disabling the item : ‘Do not apply move constraints to the curve’ in the contoured move step). If I disable or enable this item, and I generate some LabVIEW code, I don’t see no difference.

Another question is the kind of libraries I should use.  I have seen there is a NI-Motion library, a library for 73xx-cards, a motion assist library. I am now using the 73xx-cards library because I us a PCI-7358 card.

Bottom line : What is the best way to make a contoured move in LabVIEW, and als have a good control over speed and acceleration ?

Thanks, Wim

[cornewesteneng]

Dag meneer Kaan,

De bovenstaande vraag wordt behandeld onder Service Request nummer # 1194948.

Gisterenmiddag heb ik u hierover een mail gestuurd, zou u mij kunnen terugmailen? 

Met vriendelijke groet,

Corné Westeneng

Application Engineer

NI-Netherlands

[ThiCop]

Hello Wim,

I'm going to do the communication through this channel, because then teh answer will also be shared with all our forum users.

Can you share an example of the pvt- and/or pt-files you're using?

Depending on how your files are constructed it could be causing that "jerk" behaviour..

Can you also give some extra information about the real-life set-up you're using to evaluate the behavior? ("jerks", acceleration,..

I think there might be some confusion about the kind of "libraries" that exist.

When you talk about the libraries you see from inside LabVIEW, then you should indeed see the 73xx section and the Motion Assistant section on your function palette in the Vision and Motion Category.

You'll also see a SoftMotion subsection, but normally should not have a subsection called "Motion".

For your case the 73xx subsection will be the most appropriate one. The Motion Assistant is actually an API that allows you to access (some of) the functionality of the Motion Assistant.

When you're new with these Motion functionalities, then the best approach would be to first start with the Motion Assistant.

This will allow you to do LabVIEW code generation from inside the Motion Assistant.

By looking at the generated code you can then look at how everything is translated to LabVIEW code.

In this code you'll see that at the lowest level you'll be using 73xx functions/VI's for most of the realisation.

Other parts of the moves are generated by "special" generated VI's by Motion Assistant.

For a contour move this includes for example information about how everything is buffered so that the move can be correctly executed.

How familiar are you with LabVIEW and Motion applications?

Thanks in advance for the replies!