need some help with the simulink PID block

Cant seem to tune this thing out.

First of all, let me say this, i am tuning a massive system that is not able to be realized by a trasnfer function. The model is a physical system. So using the tuning tools is out.

I cant seem to figure out what my controller is undershooting so badly.

For example, i have a full scale error possibility of about -5 to 5 with the setpoint being zero essentially or zero "error"

The controller does not even try and do anything until i am at nearly -2

Then -2 comes around and it sky rockets badly. Next thing you know im at 5

The integral gain is already very very small. the controller is running at about 200 hrtz which is reasonable for this type of system.

This is a generic thought question.

Why would a controller have asymetrical overshoot and undershoot. For example, if i have overshoot, i expect it to be the same percentage wise above and below the setpoint. My undershoot is significantly worse and i cant figure out why.

Any idea?

[nick]

Hi Robert,

Kindly share the plot you obatined for the response of the system for a better understanding of the question and also indicate the expected behaviour of the system.

[Arkadiy Turevskiy]

Hard to say anything based on information you provided. Your model could be nonlinear, not clear why in general you would expect to have symmetrical overhsoot and undershoot.