Peter Nachtwey
Member
Pauly's5.0's thread on PID gain tuning brought up an interesting issue. The derivative gain or time constant can be adjusted to dampen the system response but how or why does it work and how must the derivative gain gain when the proportional gain is changed?
Look at this site
http://www.engin.umich.edu/group/ctm/PID/PID.html
links have been posted to this site before but I really don't think anybody, including those that wrote the pages, really understands what they say.
First we will start with something simple. Look at the proportional control example. What value of Kp will result in in critically damped system? What happens if Kp is lower than the critically damped value. What happens if Kp is greater than the critically damped value.
To solve this one must be able to factor the denominator. It is the poles or roots of the denominator that mainly determine the response of the system.
Hint. To be critically damped the two poles should be real and equal. To be over damped the two poles will be real but not equal. To be under damped the two poles will be imaginary.
We will see how many work this out. The proportional derivative problem will be for tomorrow.
Look at this site
http://www.engin.umich.edu/group/ctm/PID/PID.html
links have been posted to this site before but I really don't think anybody, including those that wrote the pages, really understands what they say.
First we will start with something simple. Look at the proportional control example. What value of Kp will result in in critically damped system? What happens if Kp is lower than the critically damped value. What happens if Kp is greater than the critically damped value.
To solve this one must be able to factor the denominator. It is the poles or roots of the denominator that mainly determine the response of the system.
Hint. To be critically damped the two poles should be real and equal. To be over damped the two poles will be real but not equal. To be under damped the two poles will be imaginary.
We will see how many work this out. The proportional derivative problem will be for tomorrow.