> That part I understand (your drawing), its a basic phase lock loop. > What I am having trouble with is the Fury's commands relationship.
OK. Sorry for the BW. Basically you tune a loop by starting with the P, I, and D set to zero. You slowly crank up the P until it starts to become unstable. (Put in a small step perturbation and look at the response for ringing) Then crank up the D until it stabilizes, then crank up the P again. When you have got a stable fairly well performing loop, you introduce some I. You may have to tweek P and D to keep stability. It looks like your system has an overall gain (DACG) and a P and D controller gain. This is not uncommon to avoid switching a bunch of caps. FWIW, -John ============== > > The Fury controller has the following SERVO commands to set up the loop: > > SERVo:DACG which is the DAC gain, a control voltage range ? > range is 0.1 to 10,000 -- the DAC is 0 to +5V > > SERVo:EFCS which is the EFC Scale, proportional gain of the PID loop > range is 0.0 to 500.0 -- 0.7 example for a good double oven and 6.0 for > a simple single oven > > SERVo:EFCD which is IIR filter time constant > range is 0.0 to 4000.0 -- example between 10 and 50 > > Thanks - Brian KD4FM > > > On 7/27/2010 8:36 PM, J. Forster wrote: >>> I read the article on PID on Wikipedia last night. I do not fully >>> understand it, but I see/learning some of the relationship. >> >> Here's a very quick primer: >> >> Consider a very simple control position servo loop: >> >> >> Pos. Input --- + (SUM)--- PID --- AMP> --- MOTOR ===== Output Pos >> |- || >> | POS Sensor >> | | >> ----------------------------------- >> >> >> If you put an upwards step into the Pos Input the output of the SUM goes >> up. This is applied to the AMP via the PID network and the MOTOR stasrts >> up, turning the output shaft. As the Output shaft turns, the position >> sensor output rises. That subtracts from the commanded position in the >> SUM, reducing the AMP input. >> >> Thats how the P = Proportional signal drives the loop to null. >> >> However, in order for the motor to turn some non-zero voltage needs to >> be >> applied. As the SUM output approaches zero the motor drive ceases and >> the >> loop never reaches null. So the I = Integral term is added. If the loop >> stops just shy of null, the SUM output will not be zero. The I >> Integrator >> takes the near-null voltage and integrates it (Vsum dT) which will >> eventually rise sufficiently to drive the motor to null. >> >> However, the motor does not stop instantly when the SUM reaches zero >> because of inertia, so it overshoots. So the D = Derivative term >> (dVsum/dT)is added in to cut the motor drive as the loop approaches >> null. >> >> Note, in general the I term is destabilizing and the D term is >> stabilizing, as long as you are considering frequencies below where the >> othy components have significant phase shift. >> >> FWIW, >> >> -John >> >> ================= >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
