Robust PID controller design using convex-concave optimization: Application to an unstable system

摘要

This paper shows a PI with phase-lead controller design using convex-concave optimization. The phase-lead term is added to reduce a high frequency measurement noise effect. By fixing all parameters of the phase-lead part, the optimization program searches the remain parameters subject to robustness constraints. The optimization constraints are functions in a frequency domain. The design problem can be solved by frequency gridding on a software package CVX. Experiments on an unstable magnetic levitation system are presented. The proposed controller shows significantly better performance than a robust H∞ controller designed by a standard method on the same unstable system.