How to find steady-state Operating point for a vehicle model built using Simscape?

What I essentially try to do is to control ICE speed with a PI controller. the model is attached to this message.

Below is the workflow that I follow:

1. find model steady-state operating point
2. linearize at operating point.
3. validate linearization with Frequency Response Estimation
4. everything good? then continue with PI tuning using Control system Toolbox.

for step 1 and 2 I use Linear Analaysis Tool.select "trim model" from operating point drop-down. then specify states/known/constrains. once, trimming is done, I get Bode plot from Linear Analysis Tool.

In the trim window, there are several variables that I don't know what to do with them. They are highlighted in picture below

Question 1) What do highlighted variables represent?

Question 2) What should be the variables specifications as state/known/constrains?

To my understanding, I selected engine speed and vehicle speeds as state variables since I want to design Engine speed controller. Correct me if I am wrong.

Question 3) How to handle linearization and operating point search for a Simscape model? MATLAB help recommends "projection-based trim optimizers" to produce better ttrimming results for simscape models.

There are few optimization methods. I don't know which to select and what should be the "optimization option" setting.

Thank you, Sajad

[SAnbaran]

Do not try this method of linearization when dealing with simscape models. but instead linearize your model at t=snapshot.

https://www.mathworks.com/matlabcentral/answers/467606-why-i-can-t-tune-design-pid-for-a-vehicle-modelled-with-simscape

Answer 1

[Veer Alakshendra]

Hi Viyan. I would recommend you to watch this video: https://www.mathworks.com/videos/trim-linearization-and-control-design-for-an-aircraft-68880.html

[SAnbaran]

Thank you Veer, I already watched the video.I followed the instruction in the video. I selected Engine speed and vehicle speed as state variables because I intend to control engine speed. However, trimming was not successful.

Could you please tell me where I am doing wrong?

And is it necessary to have multi-speed transmission to be able to design vehicle speed control? the control goal is "reference tracking".

Thank you,

Viyan (Sajad)