servo motor

[SeeChew]

Hi All,

Currently I am working on a project involved programing LabView to control an AC servo motor. I have done some simple simulation and controller design algorithm on Simulink and I wish to implement my controller from Simulink to LabView and I am struggle to find the way to input my controller in terms of transfer function. I know there is an add-on toolkit for Control Design and Simulation in LabView, but due to tight budget, I could not purchase that add-on. Therefore I am posting this to ask whether is there any other way I can design/test the controller that I design from Simulink to LabView.

Thanks.  

*P.S. Attachment is the basic VI I am using to run/test my servo motor. I need to add on a controller in front, before the signal being sent to motor. 

[DavidMaidman]

I guess you want to implement some form of PID controller?

You could have a go at implementing it yourself (its not as hard as it sounds), or if you look around there are lots of free recourses you can download

[SeeChew]

Hi,

To get a start, PID can do the job. But after that, I will be implementing other controllers which involve transfer function. Possible to input transfer function with the basic package?

Thanks. 

[DavidMaidman]

The PID toolkit comes with lag/lead modules so you could use these to build a transfer function by cascading them. If you dont have these you could easily build the lead/lag blocks your self.

From memory (i have not used Simulink since i was at university) you can enter you transfer functions in discrete terms (Z) instead of S? If this is the case can you not just model your discrete transfer function and then implement the algorithm in LabVIEW?

[SeeChew]

Hi David,

Thanks for your advise.

Yes, I can model my transfer function in terms of Z (zero and pole) in stead of "s" phase. But how can I work it out/build up my own controller in LabView? Is there any tutorial on this topic?

Sorry for asking such fundamental question. I am very new in LabView.

Many Thanks.

SeeChew 

[DavidMaidman]

Hi,

sorry, when i said in terms of Z i meant the 'z transform' , probably not very clear. If you can rewrite your transfer function in terms of z (which involves discrete steps) you can then generate an alogorithm you can implement in LabVIEW.

For example: -

[SeeChew]

Hi David,

Ok, but after I have done "z-transformation", how to input to LabView? Which block/VI to use? Is there any tutorial/forum discussion that I can find more detail on this?

Thanks. 

Thanks. 

Message Edited by SeeChew on 04-29-2010 05:37 AM

[DavidMaidman]

From the z transform you can generate an algorithm that you can then enter in LabVIEW using the normal functions (shift registers, add functions etc). For example a PD controller might be described in Z and then converted to an algorithm as shown below

You could then enter this algorithm in LabVIEW

If you are still stuck I recommend you look in a good control text book which will explain it better than I can 🙂