Concurrent Control of Velocity-force Control and Energy-saving Control in Hydraulic Valve-controlled Cylinder Systems

High servo control response and high energy-efficiency are requested in hydraulic servo systems of current hydraulic machines. This investigation concurrently implements energy-saving control and velocity-force control for simultaneously realizing high velocity-force control response and high energy-efficiency for hydraulic valve-controlled cylinder systems. The velocity-force control of the hydraulic cylinder, including 1st stage of velocity control and 2nd stage of force control, can be applied in hydraulic machines, i.e. injection moulding machines. The energy-saving control implemented here contains load-sensing control, constant supply pressure control and constant supply power control. The concurrent control of energy-saving control and velocity-force control of the hydraulic valve-controlled cylinder system becomes a two-input and two-output control problem. For that, an intelligent control strategies using fuzzy sliding mode control is developed. The experimental comparisons of the four different systems, including velocity-force control with load-sensing control, velocity-force control with constant supply pressure control, velocity-force control with constant supply power control and velocity-force control without energy-saving control, are implemented for the same velocity-force profile. The minimum consumed powers in each system are compared. The feasibility of the concurrent control of energy-saving control and velocity-force control is verified experimentally.