Create a NI based PID control system? Advice?

[Brian_Beal]

As Ben mentioned, there are many PID applications that would work fine on a PC, and you would have no measureable improvement by using a real-time system.  It would be up to the developer to incorporate any error checking, or some kind of watchdog, just as it would be in a real-time system.

[hrh1818]

On Sep 24, 9:10 am, Vr6Fidelity <x...@no.email> wrote:
> I need to make a new PID control system using labview. I have a magnetically levitated shaft, spinning at 80,000 RPM and is subject to axial loads.
> &nbsp;
> It is a pretty simple. One axial input, one output to an amplifier.
> &nbsp;
> I need it to be fast, dynamic and stable.
> &nbsp;
> Does labview have these capabilities? I suppose I would need to scan the one input channel continiously, and be continuously writing a PID derived control signal which would need to be smooth, obviously not notchy.
> &nbsp;
> What hardware has the capabilities to read and write continuously and have the speed i require. I suppose 20khz input would be fast enough.
> &nbsp;
> I have a current sytem that died on me (motherboard failure) but the computer which is a 486!, the card, the software are all SUPER old, and no one knows how to use it anymore. The DSP card company has been purchased several times and is totally unsupported.
> &nbsp;
> So:
> &nbsp;
> What hardware do you recommend?
> What software? LV + PID toolkit?
> Anything else?

It is not clear as to what you are controlling. Are you trying to
control the rotational speed of a shaft or the location of the axis of
your rotating shaft. From what little you have told us it seems like
Labview is an overkill. If you want to control the rotational speed
than a phase lock loop is a better approach. If you want to control
the location of the axis of your rotating shaft than use an analog
controller.

Howard

[McCarty]

Hello Vr6Fidelity,

I will need more information on your hardware setup and application goals in order to make an appropriate product suggestion.  Please be as specific as possible in describing your hardware components, how they are connected, what signals are being passed in and out, and what you are aiming to accomplish.  In the mean time, here are some resources that you can review to gain a better familiarity with NI's product offerings.

Real-Time Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/3938

FPGA-Based Control: Millions of Transistors at Your Command (FAQ)
http://zone.ni.com/devzone/cda/tut/p/id/3357

PID Theory Explained
http://zone.ni.com/devzone/cda/tut/p/id/3782

PID Control
http://zone.ni.com/devzone/cda/tut/p/id/6440

Motion Control Technical Library
http://zone.ni.com/devzone/cda/tut/p/id/3054#Motion_Advisors

LabVIEW Real-Time Module
http://sine.ni.com/nips/cds/view/p/lang/en/nid/13742

LabVIEW PID Control Toolkit for Windows
http://sine.ni.com/nips/cds/view/p/lang/en/nid/1394

I look forward to learning more of the details so I can help guide you towards the appropriate product set for your application.

Best Regards,
Travis M.

[Vr6Fidelity]

LOL, No i am not controlling speed.

I have a rotating shaft, with passive radial bearings and a double acting magnetic thrust bearing. I would be controlling the coils to keep the shaft in a constant axial position.

[McCarty]

Hello Vr6Fidelity,

Here are three factors you should consider in making your hardware and software selections.  

1. Deterministic Control (e.g. LabVIEW Real-Time, FPGA, etc.)
2. Speed (for both hardware and software)
3. Ease of Implementing the PID Algorithm (For example, the PID Toolset works with the LabVIEW Real-Time module.  If you use FPGA, you will need to implement your own PID algorithms.)

After considering these factors, I encourage you to contact one of our sales engineers at (888) 280-7645.

Best Regards,
Travis M.   

[Gabi1]

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@Vr6Fidelity wrote:

I would be controlling the coils to keep the shaft in a constant axial position.

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magnetic coils? in that case i will back up Ben, the PID can work on normal PC. the PID control for electromagnetic fields is inherently slow, unless you would have a large set of parallel MOSFETs.

[McCarty]

As an amendment to my last post, I would like to add that a PID (FPGA).vi does exist.  This VI does make it easier to implement PID algorithms in an FPGA environment.

[McCarty]

I would also like to add that, as of PID 8.5, we have improved and added the FPGA VI to PID Toolkit.

Best Regards,
T. McCarty