Design And Research Of The Cable-driven Manipulator

With the rapid development of modern industry and artificial intelligence technology,the performance of robot is becoming stronger and stronger.It can effectively replace human to perform many dangerous and high-intensity operations,and also can complete some tasks that cannot be completed by human.However,the traditional rigid manipulator has a large volume and weight,so it has shortcomings in endurance and safety.With the characteristics of light weight,low power consumption and good flexibility,cable-driven manipulator has been widely used in many fields.Therefore,the cable-driven manipulator has become the research hotspot of many scholars,so this paper has carried out some research on the cable-driven manipulator.In this paper,the coupling phenomenon of joint motion of cable-driven manipulator is analyzed,and two decoupling methods of joint motion of cable-driven manipulator are proposed.Aiming at the design difficulty of cable driven mechanical arm wrist joint,a compact and lightweight 3-DOF parallel wrist joint is designed in this paper.The wrist joint has a large range of motion,and its structure is simple.At the same time,the driving rope of each joint does not need to cross the other two joints,which greatly reduces the influence of motion coupling between joints.In order to apply the decoupling method and wrist joint to the cable-driven manipulator,a six degree of freedom cable-driven manipulator is designed,and two kinds of rope pre tightening mechanisms are designed.Secondly,based on the six degree of freedom cable-driven manipulator,its kinematics and motion performance are analyzed.According to the characteristics of the mechanical arm wrist joint,the mapping from the operating space to the driving space of the wrist joint is established by applying the transmission theory of the cross universal joint.Then the mapping relation is extended to the whole manipulator,and the forward and inverse kinematics solutions of the manipulator are obtained.In order to analyze the motion performance of the manipulator,the motion space of the manipulator is analyzed.The results show that the manipulator has a large motion space,which also shows the feasibility of the design scheme.Then,considering the influence of the elastic deformation of the rope and the friction between the rope and the rope pulley on the cable-driven manipulator,this paper analyzes the force of the rope drive and the dynamics of the basic rope drive system.Because the elastic deformation of the rope will make the joint angle of the cable-driven manipulator offset and vibrate in the process of motion,in order to study the influence of the elastic deformation of the rope on the cable-driven manipulator,this paper selects one of the decoupling methods to design a two degree of freedom cable-driven decoupling manipulator,and establishes its joint angle offset model by applying the winch transmission stiffness theory.Finally,in order to verify the effectiveness of the decoupling method and the correctness of the theoretical model of joint angle offset,a test prototype is made and related experiments are carried out.The experimental results show that: when the torque of the forearm joint is 0,the change amplitude of the joint angle offset is 0.72 degrees,which verifies the effectiveness of the decoupling method;the calculation error of the joint angle offset model is less than 0.02 degrees,which verifies the accuracy of the model.Furthermore,the dynamic test results show that the dynamic decoupling performance of the manipulator joint is good,and the greater the preload,the smaller the joint angle offset.