Pressure control of electro-hydraulic servo loading system in heavy vehicle steering testboard based on integral sliding mode control

Abstract

Heavy vehicle steering testboard has a key role to play in the fundamental research of heavy vehicle steering performance, and pressure control of electro-hydraulic servo loading system is the precondition and foundation for achieving accurate dynamic loading of heavy vehicle steering testboard. Commonly used proportional–integral–differential control easily fails to track target pressure signal with high amplitude and frequency, while integral sliding mode control is capable of realizing pressure tracking with high accuracy in engineering for its strong robustness and simplicity. A nonlinear mathematical model of electro-hydraulic servo loading system is established, including the nonlinear characteristics of valve-controlled cylinder system and tire elastic force, and an integral sliding mode controller is also designed in this paper. For further comparison and analyses, based on particle swarm optimization and integral of the time absolute error criterion, a proportional–integral–differential self-tuning controller of electro-hydraulic servo loading system is proposed as well, and the corresponding optimal proportional–integral–differential control gains are obtained. Both numerical simulation and experiment results confirm that, compared with proportional–integral–differential self-tuning control, integral sliding mode control can effectively suppress the disturbance of external loads and reach a better pressure tracking performance.