Research On On-orbit Assembly Method Of Manipulator-assisted Space Truss

Space truss is the basic skeleton of large space facility,so in the process of constructing large space facility in orbit,the in-orbit construction of space truss is a very important part.In the vacuum and weightless space environment,it becomes very difficult to build large-scale space truss in orbit,and the manual assembly of truss by astronauts in orbit is not only inefficient,but also brings a series of safety risks during the long time of extravehicular operation.To address the above problems,this paper aims to establish a scalable large-scale space truss structure,develops a set of space truss in-orbit assembly scheme,and applies robotic arm technology to assist in the process of space truss in-orbit assembly to complete the in-orbit construction of space truss,and uses theoretical analysis,structural design,numerical calculation and simulation analysis to verify the feasibility of the overall scheme.The main research contents of this paper include:Firstly,a trigonometric space truss unit configuration and a truss expansion method in orbit are designed from the large space truss in-orbit assembly theory.AnsysWorkbench simulation platform is used to perform dynamic modal analysis on the trigonometric space truss structure to study the modal frequency variation of different materials of truss and select the material with better performance in preventing low frequency vibration.The modal analysis of space truss structure with different effective areas is then carried out to analyze the modal frequency variation of each order as the truss area expands.Secondly,in order to establish a scalable large-scale space truss structure,a space truss on-orbit assembly platform is designed.The platform can be attached to the space truss in the weightless environment of space,and can be moved horizontally and vertically on the truss plane,and a six-degree-of-freedom robotic arm is installed above the platform for grabbing truss materials for on-orbit assembly,forming an assembly effect of "walking while paving".Thirdly,the basic kinematic analysis of the six-degree-of-freedom robotic arm above the space truss assembly platform is carried out,and the standard D-H parametric model of the six-degree-of-freedom robotic arm is established through the study of the positional transformation of the space linkage coordinate system,and the kinematic solution of the six-degree-of-freedom robotic arm is completed,and the working space of the robotic arm is further analyzed to determine the orientation of the robotic arm on the truss and to ensure that the end-effector can reach the truss.all working nodes.Finally,the trajectory of the robot arm is optimized for the process of assembling truss rod sets.The classical 3-5-3 polynomial interpolation method is used to plan the trajectory of the robot arm,followed by the optimal time as the optimization index,and the particle swarm algorithm is used to design the trajectory optimization scheme,and Matlab simulation software is used to verify the parameter indexes of each joint and the trajectory running time after optimization.