Impedances, Efforts and Flow in Passive Systems

Jan 06, 2005 5 Replies
T

While trying to design a controller for a passive system, I am a bit confused regarding the problem stated below:



All such functions are written like:



e(s) = Z(s).f(s) where e is effort, and f is flow, for example, a mechanical system would be described as



F(s) = Z(s).V(s) where F is force, and V is velocity.



I am getting confused that all this is in Laplace domain, what if I were to use this concept in time-domain? How would I translate a hybrid impedance transfer function from Laplace to time? Ofcourse I can take I.Laplace, but I feel I am missing something very basic.. Any help???



Thanks.



Tom



Vote
Twitter Facebook LinkedIn
T

In addition to it.....

Lets say if I use Z(s) as a Simulink Block, could the inputs and outputs be treated as f(t) and v(t) instead of F(s) and V(s) or would I have to change something? I am really getting confused. What is the laplace transform of an input signal v(t) which is generated by a singnal generator in Simulink? ..... Help me....

Vote
Twitter Facebook LinkedIn
T

In Simulink a transfer function block Z(s) is turned into a time-domain differential equation and executed. Similarly a discrete-time H(z) is turned into a difference equation.

In Simulink the Laplace transform of an input signal is never taken -- everything stays in the time domain.

Vote
Twitter Facebook LinkedIn
T

Ohh okay. Tim Thank you very much for your explanation. Now it makes sense to me, I think. But just as a matter of discussion, so it means laplace domain is for design and analysis only, it is never used for simulation!! Am I right here?

-Tom

Tim Wescott wrote:

time-domain

Vote
Twitter Facebook LinkedIn
T

Thanks Tim. Now I understand it. I visited your site too. It is very nice, esp. enjoyed your articles on z-transforms. Good work.

Vote
Twitter Facebook LinkedIn

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required