Re: Servo rate of 20kHz

    Maybe i'm doing something wrong,

    but i have kind of simple setup for didatic purposes.

    It's a DC motor controlled by 2 pins of the parallel port via an H bridge

    And 2 input pins from the parallel port to read an encoder, and get channels A and B.

    that's not pratical for most projects, but i find it quite interesting to show RTAI in action doing the Quadrature of the encoder position.

    Well, i use rt_sleep of 1 uS, and my loop is quite simples, such a P controller. Seems that i'm getting 1uS.

    I don't know if this helps anyway

Rafael

L.C. Karssen wrote:

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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