Mechanism Design And Kinematic Analysis Of A Cable-driven Anthropomorphic Arm

With the development of technology,traditional industrial manipulators are widely used in industrial manufacturing and military field for their high speed,high precision,and high robustness.However,with the increasement for human interaction in robotic arm,when it is applied to the field of home services and medical assistance,the disadvantages of the industrial robotic arm appear,such as higher quality/ large inertia/ small self-weight ratio and poor flexibility due to the motor placed at the joint during the movement,limiting its respond ability when moving at high speed.A new driving method is needed to overcome the defects of traditional mechanical arm,however the cable driving technology provides a new way.Based on the cable,this thesis proposes a seven degree-of-freedom anthropomorphic robotic arm with high rigidity and high load-to-weight ratio.Starting from the structure of the human arm,this thesis studies its structure / motion /function characteristics and reveals its motion principle.According to the motion mechanism of human arm,the traditional rigid driving design method of humanoid mechanical arm is changed,the bone is equivalent to a connecting rod,and the muscle is equivalent to a cable driving mechanism.Combining the intrinsic characteristics of arm and cable,a new type of humanoid robot modular drive unit is developed.Compared with the traditional method,cable-drive method is more complicated.The cable is a flexible medium with poor stiffness performance,and slippage between the cable and the joint is prone to occur.To solve this problem,we analyze four main factors impacting transmission performance: cable material,preloading method,cable groove form and transmission winding method.Select the appropriate cable material according to the force school core,design the pensioning method of the moving shaft system,the large-size singlechannel parallel cable groove and optimize the cable drive layout according to the mechanical structure,and the functionality of the design is verified through the motion experiment.Then,we solve the kinematics equations of robotic arm,including the kinematics of the modular mechanism(three DOFs parallel module and single DOF tension amplification module),and we construct the kinematics representation of this anthropomorphic arm using vector method.In order to verify the effectiveness of this kinematic representation of the manipulator,MATLAB is used to carry out simulation analysis and verify the feasibility of the kinematic equation.The working space of the manipulator was obtained,which provided the basis for the subsequent kinematic experiment analysis of the manipulator.According to above design principles,each module were manufactured.After completing assembly process,anthropomorphic arm experiment is carried out to verify the effectiveness of design method and kinematic model,which provides a way to develop humanoid robot arm.