alternate for 'ss' for state space representation

'ss' for state space representation doesnot work in Matlab since i don't have license for that. Is there any alternate method of representing in state space ? Else how do i get the code running in the background of 'ss'.

Answer 1

[Walter Roberson]

ss() creates an Object that is recognized by other related commands that are in the same toolbox. Since you do not have the license for ss() you do not have the license for the other commands. You would need to do the research to figure out how to write all of the routines that you want to be able to use.

... Or you could purchase an appropriate license.

Answer 2

[Star Strider]

For a linear, time-invariant (LTI) system, create your ‘A’, ‘B’, and ‘C’ matrices (and ‘D’ if necessary) as you would for the ss function. Then use the matrix exponential expm function to calculate your system as:

y(t) = (C*expm(A*t)*B + D)*u(t)

I have done this in several Answers. For an example, see: Why does dsolve not solve this system of differential equations? (link).

It requires more coding than the Control System Toolbox functions do, however for a linear system it is certainly possible to simulate your system.

If you have several linear systems that you want to interconnect and want to model the interconnected system, this becomes much more challenging. If you are dedicated to learning control engineering, it should not be beyond your abilities!

If you have a nonlinear system, use ode45 or one of the other ODE solvers to integrate your nonlinear ‘(A*t)’ matrix.

When you do this once, you will quickly learn that the Control System Toolbox is preferable.