Time-constant robust analysis of a fractional order [proportional derivative] controller

This study discusses fractional order [proportional derivative] (FO[PD]) controller tuning rules for robustness motion control systems. According to the proposed method, the controller is designed simultaneously satisfying the robustness property with respect to time-constant variation and the desired phase margin criteria. In this study, the authors focus on the first-order plus time delay model with an integrator. A systematic tuning rule is developed for the FO[PD] controller. Numerical computation of the tuning formulae and the relationship between design specifications and design parameters are both discussed. For simplifying the computation and achieving online tuning, the crossover frequency has been discussed. Experimental results are included to validate the proposed tuning method.