On Wed, 31 Oct 2012 19:28:30 -0700 (PDT), Peter C. Wallace wrote:
> After spending some forum time trying to help a customer with tuning
> a torque
> mode drive, I have noticed that ferror is calculated incorrectly and 
> if
> minimized will result in less than optimum actual error.
>
> The error appears to be that ferror is calculated before the 
> trajectory is
> calculated so it always compares the previous waypoint with the 
> current
> (encoder) position. This is easily see by the difference in ferror 
> from the
> PID error (they should be the same)
>
> This causes a value equal to the velocity in machine units per 
> second*servo
> thread_period to be added to the ferror.

interesting.  Can you give your preferred technical reference for the 
PID error calculation for review?  I am sure I can dredge several up, 
but you might have a clearer reference.  Also, have you located the 
offending code?  If so what file and line number?

   Thanks and best regards,

   EBo --


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