If I can't get the required specifications using PID or Lead-Lag compensators, what other compensators or controllers that exists that I can use to meet the settling time, and steady state error requirements ?

 

You might look at a PAC instead of an PLC. Depending on the PLC microprocessor from an input signal to an output there is a delay (sometimes 20 milliseconds). PAC controllers have about a 2 millsecond delay. If you describe more of your application. Like what sensor you are using using and how it is creating issues. That would be of help.

 

If you need to wing it, Fuzzy Logic control, running on a microcontroller, can be easier understand and tweak for the desired results as compared to PID.

 

I have the transfer function of my plant which is third order and i'm connecting it in unity negative feedback loop. I have specifications of settling time and % overshoot and steady steady state error to a ramp input to meet BUT I cant approximate the system as a second order to do calculations. How can I meet the required specs by showing manual calculations ?

 

What type of sensor are you using? This might give us some insight to resolve your issue. Maybe a fractal algorithm might be in order.

 

Perhaps this will help.

 

Hello everyone, thanks for your help, ive been able to design using state space and relocate the poles... ive calculated the gains for state feedback but everytime the output becomes unstable when I model the state space on simulink, whereas the results are okay when I use transfer function directly....

 

Hello everyone, thanks for your help, ive been able to design using state space and relocate the poles... ive calculated the gains for state feedback but everytime the output becomes unstable when I model the state space on simulink, whereas the results are okay when I use transfer function directly....View attachment 191513

Hi,

I was going to suggest state space, ie state variable feedback.
I dont think you can beat that if it is done right.
Beware the theory vs implementation where you could get unaccounted for clipping of signals.

What is this system supposed to do?

 

Hi,

I was going to suggest state space, ie state variable feedback.
I dont think you can beat that if it is done right.
Beware the theory vs implementation where you could get unaccounted for clipping of signals.

What is this system supposed to do?

Thank you I have been able to do it , I just had to design a controller to meet certain specifications on a sampled signal. Thanks again