Acceleration Data for Quarter car in simulink state space model

Hello everyone, I m trying to plot acceleration vs time graph in Simulink for the quarter car model. As I m taking the output from this point as I have attached the pic the G.A PID is giving more acceleration value than the passive system. Can u suggest me what I m doing is correct or wrong or there is another way we can plot the graph for acceleration vs time?

[Birdman]

Share your model.

[raju patel]

I cant share my model. If u can give me some idea. I can give u screen shot of dispalcement curve.

[raju patel]

Still, the same problem is occurring. My doubt is that the point what I have marked in 1st photo is correct to point to take acceleration value.

Answer 1

[Birdman]

Since we do not know your model, there can be several situations for this:

1- You may have modelling error.

2- You may have your PID incorrectly tuned.

3- Your solver may not be suitable for what you are doing.

4- Your step size may become too small during the simulation.

etc. etc.

[raju patel]

Can I plot acceleration vs time graph by taking displacement curve.

[Birdman]

Take its derivative twice and see the results.

[raju patel]

It will generate spikes like curve

[Birdman]

Then the basic solution is to filter them. Are the spikes occuring at high or low frequencies?

[raju patel]

lower frequency

[Birdman]

Then apply a basic highpass filter of 10Hz and see whether the spikes are gone or not.

[raju patel]

Still, the same problem is occurring. My doubt is that the point what I have marked in 1st photo is correct to point to take acceleration value.

[Birdman]

That might not be because as I said maybe you do not set your PID well. I do not know what you did, therefore my advices are limited and general.

[raju patel]

Can u share me data were u have taken acceleration as output

[Birdman]

I would take the second order derivative of the output(displacement) and then filter it with a reasonable transfer function.

[raju patel]

It got solved in excel by doing double differentiation. But still how to get Acceleration graph in Matlab. Do poles of PID affect the simulation for acceleration vs time graph?

[Birdman]

Are you using ideal or parallel PID? An integrator won't do so much but what else are you using?

[raju patel]

Ideal PID with nonlinear MR damper for vibration reduction.

[Birdman]

Well, with this set of informations, all I can say is said in my initial answer. The rest is yours.