Energy-saving adaptive robust control of a hydraulic manipulator using five cartridge valves with an accumulator

In this paper, a novel energy-saving control strategy is proposed for the accurate motion tracking of a hydraulic manipulator. To achieve independent pressure regulation for each chamber of the cylinder, as well as energy recovery during the back-and-forth movement of the cylinder, a hardware configuration with five low-cost programmable cartridge valves and an accumulator is developed to control the motion of the cylinder. Based on the hardware configuration, a novel multilevel control algorithm is proposed, which consists of the desired motion and pressure tracking control level (level I), the flow distribution level (level II), and the offside pressure profile planning level (level III). The proposed approach is theoretically shown to be able to minimize the energy consumption of the system while maintaining good motion tracking performance. Experimental studies confirm that the proposed strategy can indeed achieve both accurate motion tracking and minimum energy consumption simultaneously. Compared with the previous four-valve scheme and five-valve flow regeneration scheme without the use of accumulator by Liu and Yao, the proposed strategy has much less total energy consumption and equally good tracking performance.