Design of a manipulator end effector used to twist screws
YU Xue wen, HOU Yue yang, LU Shan, ZHANG Xiao ming, WANG Feng wen
(Shanghai Key Laboratory of Space Intelligent Control Technology, Shanghai Aerospace Control Technology Institute, Shanghai 201109, China)

Abstract: Aiming at the application requirements of the spacecraft on orbit fine operation, the facility used to twist screws was investigated. An end effector was designed for a space manipulator twisting screws automatically. The effector was rotated by the manipulator s end joint motor, and an electromagnet was used to take up or put down a screw, which was allowed to move back and forth without changing the tolal attitude or position of the space manipulator by means of the compression and extension of the back moving spring. The tightening torque was real time monitored by the manipulator s torque sensor. A flexible adaptive method was presented to twist screws based on smart hand eye camera recognition and measurement, the measurement accuracy and tightening torque were tested in ground based simulated operation. The experimental results show that the end effector has simple mechanical structure and is easy to operate and control, it realizes the designed function and can be reliably applied for twisting screws operation while controlling the tightening torque appropriately.

Key words: space manipulator; end effector; twist screw; electromagnet; backmoving spring