Stefan Sczekalla-Waldschmidt wrote:
> 
> Hi,
> 
> Tjaart van der Walt wrote:
> >
> > Good advice. I have noticed another thing that can make your
> > system much more immune to the low-frequency I-oscillations :
> > Reset the I-value to zero whenever P=0.
> 
> looks like a good Idea - BTW did you try to optimize your PID-paramters
> according to Ziegler-Nichols ?
<GRIN> I optimised them according to Tjaart-Experiment!

The resetting of I compensates (among other things) for 
the digital nature of the calculations. Running 16 bit 
PID values in a PIC is not feasible, so I pulled a few 
tricks out of the hat. Another, is to only accumulate 
the I value every 10-50 (settable) samples. Effectively 
this divides the I term which is always much smaller 
than the P or D terms.

-- 
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