Finding operating points w. R2012b

Are the functions "findop", "linearize", and 'operspec" still supported in R2012b? They are discussed in the documentation, but when I ask for help on them using the MATLAB command line it says the functions cannot be found. (I do have the Control System Toolbox.) And if these functions are no longer available, how does one find operating points for a non-linear Simulink simulation?

I have used "trim" with limited success, so I need a better technique.

[Ryan G]

There are ways to do certain tasks with only control system toolbox. It is typically not as 'friendly' as having Simulink Control Design and you won't have access to the GUI which makes the whole thing way easier.

You can use the linmod command to linearize and use input ports and output ports to set the I/O.

[Dave]

Thanks Ryan. I'm just finding the operating points, and the "trim" function is all I can use, I guess.

Answer 1

[Shashank Prasanna]

I believe the functions you mention are part of a product called Simulink Control Design (different from control systems toolbox).

This is listed under Simulink Product Family: http://www.mathworks.com/products/

http://www.mathworks.com/help/slcontrol/ug/findop.html http://www.mathworks.com/help/slcontrol/ug/sltunable.linearize.html

[Dave]

Thanks very much, I was not aware of this Simulink product and the difference between the two "control" products. So without Simulink Control Design, what options do I have for finding operating points?

[Shashank Prasanna]

As Ryan G mentioned you can use limod > Trim, at various points. You may search file exchange to see if there are submission that do this without the use of Simulink control design toolbox.

[Dave]

Thanks again. Great suggestion about searching the file exchange. It turns out there is an app called "trimmod" available that finds operating points using only MATLAB functions. And it includes a GUI. The GUI is not a clean as the Linear System Tool's, but it looks like it might work.

[Arkadiy Turevskiy]

These functions are indeed part of Simulink Control Design. This is a separate product that requires Control System Toolbox. Even though trimming, linearization, and control design for Simulink models can be done with other methods, this product is really the best way to go.

Check this doc page that compares Simulink Control Design with tools like linmod. In addition to better trimming and linearization capabilites, Simulink Control Design provides several other useful features - such as automatic tuning of PID Controller block, and frequency response estimation, where you can inject a chirp or a sinewave into a model and get a model frequency response, all without doing any heavy lifting. All the capabilities are packaged into a nice GUI that can also automatically generate MATLAB scripts for batch-mode processing.