A Climbing Robot for Tube-Sheet Inspection Based on Planar Parallel Mechanisms

This paper introduces a novel climbing robot for tube-sheet inspection (CRTI) that uses inner wall grippers (IWGs) to grasp tubes, enabling it to hang and crawl beneath the tube-sheet plane. The robot is designed primarily for inspecting steam generators in nuclear power plants. The CRTI based on a planar parallel mechanism is proposed, with its workspace optimized through the solution space method to address the limitations of existing systems in adaptability, load capacity, and efficiency. A modular IWG based on a wedge mechanism is introduced, featuring a load capacity exceeding 100 kg without damaging tubes, with its configuration optimized through a geometric method to enable insertion into smaller apertures. Furthermore, a forward kinematic solution method for parallel robots based on coordinate transformation is proposed, providing a unique analytical solution for the forward kinematics of all parallel configurations of this CRTI. The performance evaluation, which is grounded in singularity analysis and typical experiments, reveals that the proposed CRTI offers high efficiency, substantial load capacity, and exceptional adaptability, indicating its significant potential for future applications.