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Inverse Kinematics of a Reconfigurable Redundant Manipulator with Lockable Passive Telescopic Links

The current research on space manipulators mainly focuses on space manipulators with fixed arm lengths, such as Space Station Remote Manipulator System (SSRMS). Space manipulators with fixed configurations can no longer meet the needs of various delicate operation tasks such as capture, replacement, assembly, and maintenance. Therefore, the reconfigurable space manipulator is the future development direction. This paper proposes a novel SSRMS-type reconfigurable redundant manipulator with lockable passive telescopic links. The telescopic link adopts a passive telescopic and active locking scheme, and there is no driver installed inside except the locking mechanism. The locking mechanism is locked when the manipulator is in regular operation but can be unlocked whenever the manipulator needs to achieve reconfigure. When the manipulator's end-effector is constrained to form a closed kinematic chain under the desired length of the telescopic link, the locking mechanism is released, and the reconfiguration of the manipulator is realized through the rotation of the active joint to meet the requirements of various delicate operation tasks. Based on this novel manipulator, we propose an inverse kinematics (IK) method for the manipulator during regular operation and reconfiguration named CLVLJAP-IK. This method combines the closed-loop velocity level inverse kinematics (CLVL) method and the joint angle parameterization (JAP) method. It has the advantages of high-end trajectory tracking accuracy, avoiding joint limits and singularity. Finally, simulation experiments are carried out for the proposed manipulator, and the results demonstrate the effectiveness of the proposed IK method.