Adaptive position control of water hydraulic cylinder and its robustness

Water hydraulic servo system is an attractive system for its environmental safety. In this system, the problem for precise control is the uncertainties and/or the unmodeled dynamics which includes parameter variations depending on driving conditions and nonlinearity of system e.g. friction force, flow characteristics. In this paper, we discuss the control performance of adaptive position controller for water hydraulic servo cylinder comparing with PI controller. More specified, based on the general least square method as a parameter update law, adaptive tracking controller is constructed and its robustness for parameter change are evaluated. The experimental results show that the adaptive controller has certain robustness for parameter changes, e.g. supply pressure changes and load fluctuations comparing with PI controller.