How to simulate controller and plant without using simulink

Hello, I have a transfer function and a controller that I would like to simulate using purely matlab. I know that I can use the step() function to simulate the step response, but I would like to generate my own trajectory and input it into my system and not use an integrator such as ode45(). In simulink I can just output the output of my system and the trajectory is plotted. How would I do the same thing in MATLAB code?

The main reason I would like to do this is that I want to feed the output of my system to modify the trajectory at the input, but at a much slower rate than the sample rate of the controller. Im finding it difficult to figuring out how to do this in simulink.

Answer 1

[Robert U]

Hi Windell:

You can simulate the time response of dynamic systems to arbitrary inputs with lsim ( https://de.mathworks.com/help/control/ref/lsim.html?s_tid=srchtitle ).

Example for a second order lowpass filter:

 %%create input signal
 fs     = 50e3;
 time   = 0:1/fs:0.2;
 signal = chirp(time,100,0.2,1000,'li');

 %%create system
 system = tf(1,[1/(2*pi*250)^2 2/(2*pi*250) 1]);

 %%simulation
 [outSignal, time] = lsim(system,signal,time);

 %%plot result
 plot(time,[signal; outSignal'])

Kind regards,

Robert