Design of a hydraulic force control system using a generalised predictive control algorithm

Reports the development of a hydraulic force control system utilising a generalised predictive control (GPC) technique. Varying dynamics of the moving actuator due to variable payload or environmental stiffness, as well as changes in the characteristics of hydraulic components, make the dynamics of hydraulic servosystems conceptually time varying. This allows the application of adaptive controls as an attractive solution. A suitable model of actuator environment is established and the recursive U-D factorisation technique is adopted for online estimation of time varying model parameters. Various step and tracking experiments are performed on a laboratory electrohydraulic actuator test stand to demonstrate good performance and the promise of the developed force control system. In spite of poor dynamics and high nonlinearities (control voltage saturation, fluid flow deadband and dry friction in the hydraulic actuator) successful control tests are performed repetitively