Research on the Perturbation Stability Margin when the Controller is Fixed

The robustness and stability of the closed-loop system is analyzed with uncertainty in the form of the additive/multiplicative perturbation and the coprime factorization respectively. The difference between them is also investigated. A new method to solve the perturbation stability margin by the coprime factorization is proposed when the controller is fixed. And the perturbation stability margin is respectively researched when only the perturbation plant is coprime or when the perturbation plant and the fixed controller are coprime simultaneously. Also the equality of them is testified while the Bezout equation is satisfied. This method has solved the problem of perturbation stability margin when the controller is fixed and provided a quantitative index for the robust analysis of the perturbation plant. The simulation has proved its effectiveness