Design Of Continuous Flexible Cable-Driven Manipulator For Outer Space Application

With the rapid development of space technology,there is more and more demand for narrow space operations.When performing some tasks with narrow working environment,such as asteroid crack exploration,fault solar panel expansion,and intra-slit welding,traditional space manipulator cannot complete those tasks perfectly due to its large volume and low dexterity.Flexible manipulator with slender structure and multiple degrees of freedom becomes an optional solution to that kind of mission.In this paper,a continuous cable-driven flexible manipulator for space application was developed,which is compact in structure and flexible in motion,and can be used in narrow outer-space environment.Based on the application environment and task requirements,the performance index and function requirements of the flexible manipulator were analyzed,and its mechanical system with unique linkage configuration was designed.The cable-driven flexible manipulator includes an operating arm,a driving box and a tension sensor measurement system.The operating arm adopts the "active and passive hybrid driven segmental linkage structure",which is composed of four segments and an end-effector sub-joints.The big and small "8" type linkage rope is used in the segment to realize the coupling of the joint angles.By using movable pulley to tractive the driving cable,driving box can increases its driving stroke and reduce its size.Based on the designed manipulator structure,the forward and inverse kinematics equations of the manipulator were derived.The mapping relations among the manipulator driving space,joint space and operating space were also established.The pseudo inverse method is used to solve the inverse kinematics of the manipulator and to plan the motion trajectory.In order to realize motion control and human-computer interaction,a secondlevel control structure scheme was determined,which is composed of upper computer and embedded ARM MCU.The hardware and software of the control system were developed,and the driving cables force-position hybrid control function was realized.Based on the above work,a manipulator prototype was completed,and relevant experiments such as arc-track tracking,repeated motion accuracy testing and linkage performance testing of single arm segment were carried out.What's more,repeated motion accuracy testing and slit exploration experiments of the whole manipulator were completed.These experiments showed that the prototype has good performance and can meet the design requirements.