MATLAB Answers

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

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Sajad  A.Anbaran
Sajad A.Anbaran on 4 May 2018
Commented: Sajad A.Anbaran on 23 Oct 2019
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

Answers (1)

Veer Alakshendra
Veer Alakshendra on 17 May 2018

  1 Comment

Sajad  A.Anbaran
Sajad A.Anbaran on 23 May 2018
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)

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