Design and Motion Analysis of a Snake Robot with Serial and Parallel Motion Modes

This paper introduces a novel snake robot design that integrates serial-parallel mechanisms and underactuated variable geometry truss manipulators (VGTMs) to enhance load-bearing capacity and stiffness without significantly increasing system complexity. The underactuated VGTM-based manipulator, featuring both active actuators and passive lockable joints, aims to perform precise manipulation tasks with high payloads in narrow space. A motion planning framework combining serial mechanism motion modes (SMMMs) for obstacle avoidance and parallel mechanism motion modes (PMMMs) for end-effector's pose adjustment is proposed. This study details the robot's structure, motion modes, kinematics, and a tailored motion planning framework, supported by a case study, to address the challenges of shape adaptive operation in confined environments.