Characteristic Model-based Generalized Predictive Control for Electro-hydraulic System with Dead-zones and Parameter Uncertainty

Abstract

In the paper, the electro-hydraulic system (EHS) is regulated by the proportional directional valve (PDV) which has nonlinearities such as the dead-zone. Furthermore, the effective bulk modulus varies with the temperature and the entrained air in EHS; there exist the nonlinear friction forces and the unmodeled dynamics as well as the square root relationship between the flow rate and the pressure in EHS. All these factors make it difficult to design the controller for EHS. The characteristic model (CM) is used to describe the relationship between input and output of EHS whose exact mathematical model is difficult to obtain. The gradient method through projection modification is utilized to estimate parameters of the CM. The CM-based controller with generalized predictive control (GPC) is designed to make the load track the desired position precisely. Simulations demonstrate that the CM-based GPC controller has a better performance in dead-zone compensation and adaptation with parameter variation than the proportional integral derivative (PID) controller.