| This paper mainly studies design and simulation of the electro-hydraulic servo control system of lower limb exoskeleton robot. Lower limb exoskeleton robot is a kind of biped robot wearing on the body, which is controlled by the body. It has human smart and strong driving of robot, so it will be widely used in military, assistive and helpage etc in the future. As Electro-hydraulic servo system has many advantages such as high precision, fast response speed, great ratio of power to mass, it is widely used in the field o:xoskeleton robot driver. Electro-hydraulic servo system performance, especially in human gait following performance has a decisive influence for external skeletal performance of the robot, therefore, it is important to research lower limb exoskeleton robot electro-hydraulic servo control system design and performance, which is the research emphasis in this paper.First of all, according to the human body size and gait movement characteristic, the exoskeleton robot model is designed by using three-dimensional software. At the same time working condition of electro-hydraulic drive system are determined through the gait analysis and dynamic analysis. Three principle scheme of hydraulic servo system of the exoskeleton robot have been put forward and determined by considering factor, such as actual request, cost etc. Then the electro-hydraulic servo system key components, such as hydro cylinder, servo valve, hydraulic pump, overflow valve, oil tank, etc, has been designed or selected, assembly drawing of electro-hydraulic drive system has been acquired.Secondly, by using flow continuity equation and force balance equation of the hydraulic cylinder of the electro-hydraulic servo valve and asymmetric hydro cylinder, the valve control cylinder’s dynamic mathematical model is deduced; By using the method of Lagrange function and the principle of virtual displacement, each load calculation model of the hydraulic cylinder of lower limb exoskeleton robot is established; Through the method of stability boundary parameter, lower limb exoskeleton robot electro-hydraulic servo system PID controller has been designed. At the same time, the human gait conditions following of the closed-loop control system have been simulated by using of the simulink simulation software. Simulation results show that the system can meet requirements of lower extremity exoskeleton robot electro-hydraulic servo system.Finally, physical modeling and simulation of lower limb exoskeleton electro-hydraulic servo system has been carried on by using of Matlab/Simhydraulics software,the feasibility of electro-hydraulic servo system has been verified. The simulation results show that the design of electro-hydraulic servo control system can meet the requirements of relevant design in this paper. |
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