A Hybrid Offline/Online Modeling Based Tracking Control for Complex Hydraulic Driving Processes

The hydraulic actuators are widely used in industry for the fabrication of all sorts of products. Due to the complexity and strong nonlinearity, such as the time-varying and nonlinear deformation force and driving force as well as the nonlinear friction, it is often difficult to gain an accurate control. In this paper, we propose a hybrid off-line/online modeling-based tracking control method to alleviate this difficulty. First, a hybrid off-line/online modeling is proposed in order to achieve the models of both the time-varying and nonlinear deformation forces and nonlinear friction, upon which a model for the complex hydraulic driving process is derived. Using this model, a tracking control method is then proposed to achieve a satisfactory control performance even when forming various workpieces. Its stability is further analyzed and validated. The experiments using an actual hydraulic actuator are performed to test the proposed modeling and tracking control method.