Development Of End Tool For Space Manipulator And Research On Its Operation Strategy

With the rapid development of space technology,extravehicular and space missions become increasingly complex and diverse,and a large number of space vehicles with different functions have been launched into space.Previously,the focus of research in various countries has been not only the launching of complex space systems,but how to ensure that the spacecraft launched can be safely,stably and permanently operated and completed the space mission.Therefore,space in orbit maintenance technology has the current research hotspot and difficulty.The space environment is characterized by high vacuum and high radiation,which makes the extravehicular maintenance activities of astronauts more expensive and high-risk.Space robots instead of astronauts can be used for orbital maintenance,which can effectively reduce costs,reduce risks and work reliably for a long time.In the field of space robot technology,it is one of the key technologies to develop the space manipulator's end operating tools for the disassembly,maintenance and assembly of spacecraft.Through the research on the related projects at home and abroad,a series of operation tools for disassembly and assembly of common connectors are developed in this paper.First of all,the overall design scheme of the end tool of space manipulator is put forward according to the requirements of on-orbit maintenance task and design index.Through the comprehensive analysis and comparison of the characteristics of the commonly used threaded connections,3 kinds of disassembly and assembly tools are designed,and the design of all parts,virtual assembly,interference checking and weight prediction are completed through 3D modeling software.Considering the radial position deviation of the end of the manipulator caused by joint flexibility and motion error,a deviation compensation scheme based on the double cross slider structure is proposed,and the motion characteristics and transmission efficiency of the slider are analyzed.A unified interface between the tool and the end effector is designed,which enables the tool to be installed safely and reliably on the actuator and accepts the two power delivered by it.The simulation analysis verifies the tolerance capability of the position and orientation of the interface.The core function of the tool is analyzed and discussed.Through analysis and calculation and finite element software,the strength of components with complex structure is checked.Secondly,the control strategy of space manipulator is studied to meet the requirement of tool operation in orbit maintenance.The switching of the control mode of the manipulator at different stages is discussed in conjunction with the screw detachment task.In view of the requirement of position accuracy in the preparation phase of maintenance task,two control methods,PD and computational torque,are discussed and compared by simulation.In order to meet the requirements of tool docking and disassembly of the connector,the impedance control algorithm based on position is established,and the control effect is verified by simulation analysis.Finally,the prototype of the operation tool is developed,and the corresponding experimental platform is built,and the relevant experimental verification is carried out.In order to verify the basic functions of the operation tool,the position deviation compensation and the gripping jaw retraction experiment are carried out,and the experimental results are analyzed.In order to verify the overall performance of the tool and related control strategies,the disassembly and assembly experiment of the connector is carried out.The experimental results show that the feasibility of the operation tool designed in this paper meets the design index,and the selection of control strategy is reasonable.