PID Ziegler-Nichols using CCS

[wakaka]

Hi there, currently I'm doing a temperature controller using 877. i know that Ziegler-Nichols can be use as a self-tuning method for PID.
But the problem is i dunno how to set the Ku and Pu.
I've search the net, but there are various equations for the Ziegler-Nichols. SOmeone plz help.....provide steps.
if possible examples on CCS plz.....
thanx

[PCM programmer]

[wakaka]

no, din manage to get that although i googled for a few times....will look into it, thankx.

[wakaka]

browse thru it, nice document PCM, thanx

anyone else? need more infos......

[Eugeneo]

I think he had more fun with the electronics and code design than the actual analysis B

[wakaka]

plz correct me if I'm wrong

The pid = Kp*E + Ki*sumE + Kd*dE/dt [1]

for the Ziegler-Nichols tuning method, it has open loop and closed loop, both has different calculations to find Kp, Ki and Kd.

The problem is if i wanna use open loop, i just substitute the constants in to the PID equation [1], or i need to use another PID equation which is an open loop? (Cause wat i understand is closed loop has feedback, whereas open loop no feedback)

Or the same equation[1] can be use for closed loop and open loop Ziegler-Nichols ?
Plz help, thanx.......

[SherpaDoug]

Without feedback it is not PID as there is no E to put into the PID equation. Z&N is only used with closed loop PID. First you should try to get a decent responce open loop. Then close the loop with PID and use Z&N to fine tune the loop constants.
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[wakaka]

dun understand...sorry....