# How to determine proper proportional gain and derivative gain for my vehicle model?

2 views (last 30 days)
Shuo Wang on 1 Aug 2016
Answered: Christoph Hahn on 8 Sep 2016
Dear sir, thanks for helping me dubug in my model. After I uesd 6 DOF joints ,everything works.Cheers! So this time I want to ask another question which makes me confused a long time. The proportional gain and derivative gain you used in the training video is 1000000 and 10000, and the proportional gain and derivative gain be used in the example of Double wishbone suspension is 10000 and 100, I'm quite confused with this. As shown in the figure, the vehicle jumped so high, my model mass is just like 220kg, so how to determine proper value for this two controller numbers in order to let the model show proper reflect to the road profile. I referenced a part of the controller from the Matlab example of Double wishbone suspension.Hence the input of the prismatic joint is changed to force.
Swarooph on 5 Aug 2016
Hello Shuo,
The best answer that I can give you is that the controller numbers are obtained by trial/error. Change it according your model (your vehicle mass etc might be different from the training or MathWorks demo examples). You can measure the force values and visualize it using a Scope to see if the numbers are close to what you are looking for and keep changing the controller parameters until this input looks desirable.

Christoph Hahn on 8 Sep 2016
Hello Shuo,
I am agreeing to Swarooph's comment. Simscape allows to model using actual physical quantities with the respective units. Choosing real-world quantities for you model will result in smaller deviations between model behavior and that of your actual car. When you don't know a quantity, do exactly what Swarooph is suggesting: make an engineering assumption. With regards to damper coefficient and spring stiffness I am assuming that the data sheets of your physical components will help you.
Does that help?
Cheers Christoph

### Categories

Find more on Applications in Help Center and File Exchange

### Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!