Continuous Rotary Hydraulic Servo Joint Structure Optimization And Performance Analysis

Hydraulic robot joints are key components in the hydraulic robot, and the fit andunfit quality of the dynamic performance directly affects the hydraulic control precisionof the robot. Hydraulic rotation angle self servo technology is the combination ofhydraulic servo control technology and servo motor control technology, and enlarge theoutput of the motor with the small power through the hydraulic servo mechanism. Thistechnology can lay a theoretical foundation for reducing hydraulic joint dimensions andrealizing oil channel built. It has been successfully applied to the hydraulic joints of therobot. This paper analyzes and summarizes the relevant literature, finding out thecurrent defects of the hydraulic self servo joint. A continuous rotating hydraulic servojoint was designed with the latest research results of the related subjects. The structureparameters of the joints are optimized by genetic algorithm. Based on this, the changinglaw of the oil inlet cavity and oil return cavity following with the rotor angle is analyzed.The flow continuity equation and the moment equilibrium equation of the joint systemare established. And then the simulation model of the system is built and systemresponse characteristics are studied, and the PID controller is used to improve thesystem performance. Finally from the angle of mechanics, the stiffness and strength ofjoints are verified according with the actual demand. In this paper, the main work andconclusions are as follows:(1) In this paper, a continuous rotary hydraulic servo joint is designed combingwith the actual situation. The main technical parameters and the performance index ofthe joint are given.(2) The structural parameters of the joints are optimized by using the geneticalgorithm according to the desired parameters, and the motor structure parameteroptimal value is obtained, making the joint volume as minimal as possible under thepremise of meeting the requirements, which lays the foundation for its practical application.(3) By analyzing the changing law of the volume of the oil inlet cavity and oilreturn cavity and double-acting vane motor instantaneous displacement following withthe rotor angle, the corresponding mathematical expressions are established, and findingout that the oil inlet cavity, oil return cavity volume and instantaneous displacementchange cycle. At some point, the volume of the chamber is changed suddenly, and thevolume of the oil inlet chamber and the oil return chamber do not changesynchronously.(4) The dynamic model of the joint was established, the simulation is carried outaccording to the model. To further optimize the system performance, PID controller isadded. The maximum tracking error is no more than0.018mrad, and the response of thesystem under different loads is simulated at the same time. The results show that themore load torque, the larger the steady error. When the load is80N m, the steady erroris1.2mrad, the system works in the case of60N m most of the time. Therefore, theoverall error of the system is small, so it can meet the requirements.(5) The finite element analysis of the valve core, valve sleeve and valve body iscarried out by using the finite element method, and the stress and strain distribution ofthem are obtained, at the same time, the natural frequency of valve core, valve sleeveand valve body and its vibration mode are obtained which provide the theoretical basisfor the design and experiment of the joints.