Re: Servo rate of 20kHz

From: L.C. Karssen <l.c.karssen_at_phys.uu.nl> · Date: Fri, 25 May 2007 09:32:40 +0200

On Thu, 2007-05-24 at 16:58 -0700, Edgar Berdahl wrote:
> Hello,
> 
> Is it possible to use comedi and RTAI to run a control loop at a  
> servo rate of 10kHz or 20kHz? We would prefer to have at most a few  
> samples of delay around the control loop.

That depends on the amount of code in the control loop, I guess. For my
experiment I've just made a control program that sets 8 DIO and 2 AO
lines with a minimum time step of 20us (50KHz). I was about the fastest
timing I could get. I use an NI-DAQ PCI-6024E card.
While performing the latency tests of RTAI (as discussed in the RTAI-Lab
tutorial of Roberto Bucher for example) I got a minimal period of 15us. 

Lennart.

> 
> Would this preclude using a controller with perhaps 10 poles and 10  
> zeros?
> 
> 
> Thanks,
> Ed
> 
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-- 
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L.C. Karssen
Department of Physics and Astronomy
Faculty of Science
Utrecht University
Princetonplein 1
3584 CC  Utrecht
The Netherlands

tel.: +31 (0)30-253-2208
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e-mail: L.C.Karssen_at_phys.uu.nl
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