i need to determine the stability of a system that consists of a PI controller, a servovalve and a thrust bearing with its reaction force linearised. all transfer functions are in the model attached to the question. if i model the step response to the change of the set point, it works just fine, however derivation of a TF for the system in the following way:
W1=tf([1000 5000],[1 0]);
W2_02=tf([0 250],[0.02 1]);
W2_12=tf([0 250],[0.12 1]);
W3=tf(,[7.5 4e4 5.5e5]);
results in the command step(CL_02) to show an infinitely increasing response.
There must be something I am missing, please, if anyone has any ideas, do share with me! Thanks a lot!