On the Design and Control of a New Generation of Reconfigurable Space Manipulators with Passive Joints

This work presents a new paradigm and a conceptual design for reconfigurable robots. Unlike conventional reconfigurable robots, our design does not achieve reconfigurability by utilizing modular joints. Rather, the robot is equipped with passive joints, i.e., joints without actuator or sensor, which permit changing the Denavit-Hartenberg parameters such as the link length and twist angle. The passive joints will become controllable when the robot forms a closed kinematic chain. Also, each passive joint is equipped with a built-in brake mechanism which is normally locked, but the lock can be released whenever the parameters are to be changed. Not only will such a manipulator have the versatility to perform different tasks but also it can be packed adequately within its designated space on the launch vehicle. Kinematics of such a robot is analyzed, and a stable control algorithm which can take the robot from one configuration to another is devised.