A Hybrid Active and Passive Cable-Driven Segmented Redundant Manipulator: Design, Kinematics, and Planning

With a light-slender and superior dexterous body, the cable-driven segmented redundant manipulators (CSRMs) are excellent candidates for operations in narrow confined space. However, their application is still largely limited due to their weak stiffness, low load capacity, and complex modeling and planning. In this article, we design a new type of CSRM with high stiffness and load capacity using hybrid active and passive cables, and propose a simplified kinematics modeling and configuration planning method. The manipulator is composed of three active-linkage segments and one active tool end-effector. Each active segment, driven by three active driving cables, has two degrees of freedom (DOFs). By utilizing the passive linkage cables, the segment can be fully constrained with high stiffness, and move with equal joint angles in nearly continuous shape. Based on such structural features, the kinematics equations about the active segment-joint variables (i.e., the equalpitch and yaw angles of the whole segment) are derived. The direct, inverse kinematics and differential kinematics are greatly simplified. To find suitable solutions under environment constraints, extended virtual joint (EVJ) is introduced for quick regional solutions searching and equivalent kinematic constraint analysis. Furthermore, a configuration planning method based on the simplified kinematics and equivalent EVJs is proposed for single obstacle avoidance and continuous narrow space crossing tasks. Finally, a prototype system is developed and typical experiments are performed. The results show the high linkage accuracy, improved stiffness, and load capacity of the developed CSRM and verify the adaptability of the proposed configuration planning method.