A Variable Structure System Controller Better Robustness

A variable structure system controller (VSSC) is proposed for robustness improvement of feedback control systems. The concept of the VSSC is illustrated in time domain, frequency domain and put into an analytical representation for analysis and design. It is applied to a simple position servo system for illustration and a complicated electro-hydraulic velocity servo system. Numerical simulating results show that the proposed VSSC improves the robustness while keeping performance of the considered systems significantly