Re: Putting the 'I' in 'PID'

Translate This Thread From English to

Threaded View

Subject
Author
Posted on

Re: Putting the 'I' in 'PID'
Rick Armstrong
04-25-2009

Rick Armstrong posted on
April 25, 2009, 9:34 pm

rate this thread

EXCELLENT
VERY GOOD
GOOD
FINE
BAD

Report it

Hi Peter,

I'm having an algebra brain fart: on page one, I'm looking at the part
where K_i ad K_p are each shown as functions of the plant params and
the desired characteristic equation. I'm assuming that we set DiffCE =
0 to do start out. Then setting s = 0 gets K_i = (lambda)^2 / K*alpha.
How do we get K_p?

Thanks,

Rick

pnachtwey posted on
April 25, 2009, 10:43 pm
Permalink

Re: Putting the 'I' in 'PID'

Setting s to 0 has nothing to do with it. The two characteristic
equations must be equal for all values of s, therefore the
coefficients for each power of s must be the same.

2*lambda=alpha+K*alpha*Kp

See this recent thread because it applies to you too.
How to get PID Padameters for a "lowpass with integrator" process
http://groups.google.com/group/sci.engr.control/browse_frm/thread/49ab4f796=
f72c43a#
Wolfgang just went through the same exercise but his 'plant' or motor
system is doing position control so his transfer function is has an
extra s in the denominator to integrate velocity in to position.
Wolfgang can tune his motor now. Wolfgang and I finished up his
thread here
because the spammers are running the use groups.
http://www.eng-tips.com/threadminder.cfm?pid=1438

Peter Nachtwey