simulink: calculating transfer function from blocks
pietro
I have created a model of a 2DOFs mechanical system. I have used simscape library. I would like to get the transfer function between mass accelerations. How can I get the transfer function of two signal? The system is linear.
Thank
Bye
Pietro
Arkadiy Turevskiy
http://www.mathworks.com/help/toolbox/slcontrol/ug/linearize.html
HTH.
Arkadiy
"pietro " <braca...@email.it> wrote in message <icjbkp$k3n$1...@fred.mathworks.com>...
pietro
Thank s a lot for your links, they are very useful. I have tried to linearize my model, but I get error. In particular I have used linio function for on a body sensor and I get the following message.
In "linearize(modelname,op,io)", the linearization I/Os io must map to a valid set of ports
of a Simulink block. Port 2 on the "tmd/seat sensor" block is no longer valid.
Where is the mistake?
Arnaud Miege
When you say "body sensor" do you mean the body sensor block from SimMechanics or one of the various sensor blocks in Simscape? If it is a Simscape-based sensor, then you need to use a PS to Simulink Converter block to convert the physical signal into a Simulink signal. The linearization I/O points have to be Simulink signals, they can't be Simscape physical signals.
You can also use the same approach as in this video:
http://www.mathworks.co.uk/products/demos/simscape/nonlinear/index.html
But instead of selecting Tools -. Control Design -> Compensator Design, choose Tools -> Control Design -> Linear Analysis. You have to set the I/O points beforehand. You can do that by right-clicking on a signal, and selecting Linearization Point -> Input Point, Output Point, etc...
HTH,
Arnaud
pietro
Hello Arnaud,
I have used the way you have suggested me: I have defined the two linearization points and then on tool->control design->linear analysis I have clicked on linearization model. At now I have got the "modelled" system frf, but I haven't the frf parameters. How can I get this?
Thank you
Bye
Pietro
Arnaud Miege
> Hello Arnaud,
>
> I have used the way you have suggested me: I have defined the two linearization points and then on tool->control design->linear analysis I have clicked on linearization model. At now I have got the "modelled" system frf, but I haven't the frf parameters. How can I get this?
> Thank you
>
> Bye
>
> Pietro
Once you have the linearized model, you can export it to the workspace:
- In the Controls & Estimation Tools Manager, navigate to "Model" under "linearization task"
- Choose how you want the linearized model to be displayed with the drop-down box (state-space, zero pole gain or transfer function)
- Click on "Export to workspace..." to export the linearized model to the MATLAB workspace.
You then have access to the state-space matrices, the transfer function coefficients or the zero-pole/gain values.
HTH,
Arnaud