System response

[sagar1990]

Hi friends,
i have made a simulink model of a mechanical system, given a feedback in order to increase damping. The time response shows an exponential fall in the amplitude of vibration.

so I felt that feedback is working, but the frequency response show no decrease in magnitude at the resonant freq peak. Also, poles are purely imaginary which is not a characteristic of damped system.

so i cant understand whether my system is actually damped or not, if not why is amplitude falling down.

Please help me if you have any idea

 

[DRWeig]

Can you describe the physical system you are simulating? Or post a picture or diagram?

We can't help at all without any information --

Pardon my asking, but is this a school project? We see a lot of senior projects this time of year.

Good on ya,

Goober Dave

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[FeX32]

sagar,
Your post is not informative. Could be a number of problems from what you describe.


Fe (IronX32)

 

[sagar1990]

It's not a school project, but I am just asking whether someone has experienced something like this. I am not posting the system because the system contains a lot of user defined functions, and I dont want you to spend time reading that thing, I am just seeking your opinion.

 

[FeX32]

If you are giving a postion feedback to a mechanical system you are essentially changing the resonant frequency. So this is why you would still see large amplitudes there. The larger the gain the more you change the frequency, not the amplitude of resonance. If you use a derivative feedback however this should reduce the amplitude of the resonance.

Cheers,


Fe (IronX32)

 

[sagar1990]

NO, i am not using position feedback, i am using only velocity feedback.
but thank you for your help.

 

[FeX32]

In that case you SHOULD see amplitude decease in 99% of systems.
Make sure your feedback is correct. Set the gain to zero ans run it again with the gain to observe he change.


Fe (IronX32)