Robust sliding mode control of offshore parallel platform

Abstract

Aiming at the posture stability requirement of parallel platform under wave disturbance, an integral sliding mode control strategy based on nonlinear disturbance observer is proposed. The nonlinear interference observer is used to observe the external disturbance and is equivalent to the control input to compensate. The introduction of the integral term in the sliding surface design is a robust sliding mode controller, which uses the saturation function instead of the symbol function in the controller. The Lyapunov stability theory is used to prove the stability of the closed - loop system. Finally, the simulation and experiment show that the nonlinear disturbance observer can effectively observe the external slow time-varying interference. The robust sliding mode controller can effectively reduce the static error and realize the fast and precise control of parallel platform under the premise of guaranteeing the robustness of the system.