Design And Analysis Of Bionic Tensegrity Wrist Joint

In humanoid robots,joints directly affect the overall movement flexibility,maneuverability and bearing capacity.Lightweight joints are an important part in the research of humanoid robots.As a key component of upper limbs,wrist joints directly affect the movement performance of upper limbs of robots.There are natural similarities between the tension-compression equilibrium state of the whole tension structure and the skeletalmuscle system of human body.Based on the physiological structure of human wrist,the subject plans to design a bionic tension wrist joint and analyze its motion performance,which has important theoretical significance and application value.The morphological structure and connection mode of bones,muscles and ligaments of human wrist are analyzed,and the physiological structure characteristics of wrist are summarized.By analyzing the movement form of human wrist,the target degree of freedom of mechanism is determined.Combined with the design concept of tension whole structure,a bionic tension wrist joint is proposed and the configuration design of mechanism is given,and the size of mechanism is determined according to the physiological size ratio of human wrist.Based on the size of the mechanism,the node coordinate matrix of the mechanism in the initial configuration is obtained,and the topological connection matrix of the mechanism is established according to the connection relationship of the members.Based on the theory of force density method in form-finding method,the force density vector of each member is obtained by using the optimization function in MATLAB,and the prestress of the rope member is further obtained,which provides a theoretical basis for the subsequent simulation research.In view of the difficulty in kinematics research of tensegrity structure,each branch of tensegrity structure is equivalent to a branched chain in a parallel mechanism according to its motion characteristics,and then the tensegrity structure is equivalent to a parallel mechanism.The bionic wrist mechanism is subjected to position inverse solution,velocity Jacobian matrix calculation and acceleration analysis.In this paper,the motion parameters of human wrist in three motion scenarios of flexion-extension,adduction-abduction and rotation are collected,and the trajectory curves of wrist mechanism are simulated.A virtual prototype of wrist mechanism is established in ADAMS,which can simulate the motion according to the given trajectory curves.The simulation results are analyzed from the aspects of motion restoration degree,stability and driving force.The prototype of wrist mechanism was developed,and the rigid component,flexible component and rope drive system were designed.An auxiliary mounting bracket was designed to solve the problem of difficult installation of tension integral structure.The driver and controller were selected with reference to the simulation results,and the control program of bionic tension wrist and HMI interface of touch screen were designed and developed.In order to realize the basic movement of human wrist,the prototype is tested,which provides a technical basis for the practical application of wrist mechanism.