Abstract: The mathematical model of electrohydraulic force servo system is analyzed firstly, then the 3D nonlinear proportional differential and cerebellar model articulation compound controller is designed for electrohydraulic force servo system with time varying flexible load. The 3D nonlinear proportional differential (PD) is insensitive to the change of system parameters and keeps the system stable when the load rigidity varies in a large range. Because of the nonlinear approach ability of cerebellar model articulation controller (CMAC), the CMAC feed forward is adopted to reduce the tracking phase error. According to the simulation and test results of the electrohydraulic force servo system with time varying flexible load controlled by 3D nonlinear PD and CMAC compound controller, the algorithm is effective to the control of electrohydraulic force servo system with time varying flexible load. At the same time this method is simple to realize in engineering and demands less computational time.

Key words: 3D nonlinear proportional differential, dSPACE, Electrohydraulic force servo system, Time varying flexible load