Design Of A Deployable Truss Type Robotic Manipulator For Grasping Large Scale Objects

The goal of this project is to design a developable truss type robot hand with high stiffness and grasping force.But at present,most manipulators are jointed manipulators,and the end-effector can't grasp large scale targets.Therefore,based on the large-scale truss type mechanism,a new type of three-prism truss type deployable robot hand was designed using mobility bifurcation,space can be saved in transit,and can complete the grasping of large targets.Based on the traditional deployable mechanism and using the mobility bifurcation,this thesis presented a deployable truss type grasping robot hand for the capture of large-scale targets.The finger was composed of a series of basic units with bifurcated motion.The grasping plane with bifurcated motion was designed based on the scissor mechanism,and the auxiliary plane was designed to form the truss structure.Two kinds of connecting mechanisms were designed between the adjacent units,the mechanical linkage made the degree of freedom of the finger kept 1 in the deploying process,the follow-up mechanism enhanced the stiffness of the finger.Because the structure of the mechanism was complex,the deploying and grasping process of the unit and the degree of freedom of the follow-up mechanism were analyzed by the screw theory.Three identical fingers were installed on the base,they formed the robot hand and worked together to complete the capture task.The coordinate transformation matrix of each coordinate was obtained by the coordinate transformation method,and the relationship between the driving displacement and the rotation angle of the unit was obtained using the geometric relation of the unit.The forward and inverse kinematics were solved.Then the kinematics simulation of the mechanism was carried out by the simulation software,which verified the accuracy of the theoretical analysis.Based on th e principle of virtual work,the stiffness matrix of the finger was established,and the importance of follow-up mechanism was shown.The dynamic model of the finger was established using Lagrange equation,and the capture process of manipulator was analyzed by simulation software.Based on the principle of virtual work,the relation equation between driving force and grasping force of the finger was established.The length of the hand's rods was designed based on the grasping force,and then the geometric parameters of the hand were designed according to the working performance of manipulator.The parameters of the grasping surface,the auxiliary face and the collinear angle of the scissors mechanism were obtained in turn.Finally,the robot hand's model was made,and the performance of the hand was preliminarily shown.To sum up,the new deployable truss type manipulator presented in this thesis had the characteristics of high stiffness and large grasping force,which provided a new scheme for the large scale targets.