If you can get a linear open loop model (using the linear analysis tools) then you can apply any number of design methods to find the P and I gains. I would recommend using a frequency domain approach (on say a Nichols Chart) to find the highest proportional gain. Then add the integral action. Aim for a fast response and good gain and phase margins 🙂

I could not understand the question. In general a PI controller establishes set-point tracking with in the given limits.

Roger Dixon That is exactly what I have been doing so far. No matter what method one uses from all methods provided by Sim Control Design toolbox, model requires to be linearized prior to begin with PI tuning,. This is where the problem starts. A poor or inaccurate linearized approximation of the model leads to poor output results. The model is highly dynamic and non-linear, so it appears that classical linear approximation of the model is not feasible.

The current values for Kp and Ki are obtained by tuning PI block based on the model approximation using 'Frequency Estimation Response'. But Still gives poor results.

Michael Short would you please provide me with some reference to read on? perhaps your thesis. Thank you.

So, I need to run the model in open-loop for multiple throttle (or Accelerator Pedal) positions. Then for each run, linearize the model at multiple operating points. Finally, tune PI for each model in closed-loop system and find the best value that suits the system design performance. Did I get it right?

Michael Short Roger Dixon

I am trying to refrain from trial-and-error approach, mainly because it would be a weak argument in the thesis and hard to persuade the panel of examiners. On the other hand, I am searching for a systematic way of tuning PIs using tools provided by Sim Control Design toolbox. I have already watched many webinars on Mathworks on this topic. They all use purely MATLAB/Simulink to accomplish this task. However, almost in all cases the modeled created in Simulink, not Simscape. I do not know why I can't do the same, or whether it is possible or there is a secret magic that I am not aware of.

What are your thoughts? is there any systematic way of tuning PI?

Thank you!