Design And Characteristics Of Hydraulic Angle Self Servo Compliant Joint With Continuously Variable Stiffness

The robot joint is the key part of the robot arm.The precision and performance of robotic arm are directly affected by the performance of the robot joint.The traditional industrial mechanical arm can not reconcile the contradiction between large output torque and high flexibility.So a hydraulic Angle self-servo compliant joint with large torque and continuously variable stiffness which can be used for hydraulic manipulator is designed in this paper,aimed at the need of industrial production and the problem of man-machine interaction safety.The joint takes into account the motion performance and flexibility.Moreover,the structure and related characteristics of the joint are studied in depth.The main research contents of this paper are as follows:(1)A hydraulic angle self servo compliant joint with continuously variable stiffness is designed.The overall structure and working principle of the joint are described.The innovation of the joint compared with the existing technology in structure is summarized.(2)The joint dynamic model with valve-controlled leakage is established.The influence of different valve-controlled leakage on joint dynamic performance is analyzed by numerical approach,and the relationship curve between valve-controlled leakage and joint stiffness is fitted.(3)The numerical analysis software was used to analyze the effects of different external load moments on joint dynamic performance,and the relationship curve between external load moment and joint load pressure is fitted.The mathematical model of the dynamic position stiffness of the hydraulic angle self servo compliant joint is established.The Bode diagram of the frequency of the load moment and the dynamic position stiffness is obtained.(4)A new structure of rotary valve is designed to reduce the cavitation at the valve port.The flow field inside the valve is simulated by FLUENT software.The change of the internal flow field's throttling characteristics of is analyzed under different valve core speed,oil supply pressure and width of valve core's annular flow field.