I have an unstable system that doesn't have a useable output when open-loop excitation is applied.
Subsequently I've used a controller to control its output. I want to use the system identification tool on MATLAB, but don't know how to calculate the open-loop input to the plant for a closed-loop system.
All the reading material is advanced and theoretical and has largely gone over my head. Can anyone explain how this open-loop plant input can be derived from known parameters of the controller and the plant output?