Sliding mode control of the hydraulic swing joint based on nonlinear disturbance observers

Abstract Due to the nonlinearity of the hydraulic position servo system and its model uncertainty, which makes it more difficult to establish an accurate mathematical model, while a single control algorithm can no longer meet the control accuracy and demand of the hydraulic servo system. In order to better study the position control method of hydraulic swing joint and improve the control accuracy, this paper attempts to address the position servo control problem of hydraulic swing joint by proposing a sliding mode control approach in which, based on nonlinear disturbance observers and the effectiveness of the algorithm is verified by AMESim-Matlab/Simulink co-simulation. Firstly, this paper briefly describes the three-dimensional model of hydraulic swing joint and analyzes the working principle of the position servo system of hydraulic swing joint. Secondly, the mathematical model of the hydraulic swing joint position servo system was established, the control algorithm was designed, and the stability of the control algorithm was proved using Lyapunov theory. Thirdly, combining the rich component model library of AMEsim platform and the powerful numerical computing capability of Matlab platform, the co-simulation of the two platforms is realized by creating S-Function interface in Matlab platform. Finally, the validity of the proposed sliding mode control strategy based on the nonlinear disturbance observers (NDOB-SMC) strategy is verified through experimental analysis of co-simulation, and compared with the traditional PID as well as the traditional sliding mode control (SMC) algorithm, which is found to possess superior control accuracy and practical application capability.