nonlinear plant model in matlab

Hi I want to use a nonlinear plant to design IMC. The controller and the inverse model are linear but I have to use the nonlinear plant in the IMC structure. I really don't know how to describe the nonlinear state space model! Should I use Simulink and call it from the Mfile or what? the system is described like xdot=-x^2+(x+1)u and y=x+u ... it's a toy plant and I know it's maybe easy but if anyone can, help me please. Thanks

Answer 1

[Sebastian Castro]

You can use ordinary differential equation (ODE) solvers in MATLAB by specifying the relationship between ydot and y.

See for example: https://www.mathworks.com/help/matlab/ordinary-differential-equations.html or https://www.mathworks.com/videos/series/solving-odes-in-matlab-117658.html

- Sebastian

[Mohammad]

Thanks, I know this but the problem is that it's not like Lorenz system that there is only a set of equations like x1dot and x2dot and ... with no output. I have a system with output equation. I don't know what to do with the output equation. Do I have to mix the two equations and have one ?!