Applying discrete dynamic integral sliding surface control to hydraulic position control

The variable structure control system is a great robust control method. However, its classical existence condition seems not enough for applying to the discrete systems. Due to the existence of the sampling interval in discrete systems, the controller can not simultaneously correct the system's response during the interval. The small switching gains are necessary in order not to be divergent to the switching surface. However, to quickly reach the sliding surface, the large switching gains have to be chosen. In this paper, based on the different viewpoint can develop the additional restriction. It does not only offer the definitions of ranges of the switching gains but also their domains. The discrete dynamic integral sliding surface control (DDISSC) can solve these problems. It can not only reduce the time to reaching the sliding surface, but also pay less control effort to achieve this surface. Finally, the hydraulic position servo control system is used to demonstrate the potential of the proposed control method. CPLD based control board implements the proposed rule by full digital technology. Simulation and experimental results show the robustness to against the parameters' variation and external disturbance.