Path-planning for the Human-arm-like Collaborative Robot with the Capability of Infinite Rotation.

With the advantages of high safety and scalability, collaborative robots are widely used in the fields of Human-Robot Collaboration and Interaction. However, the joint limits of the robot restrict its flexibility and workspace, especially in a cluttered environment. Inspired by the motion of the human arm, whose elbow joint and shoulder joint can rotate infinitely, a collaborative robot with the capability of infinite rotation of its first and fourth joints is constructed in this paper and named the IR-Robot. With the breakthrough of the joint limit, the corresponding dimension in the robot’s configuration space changes from a bounded dimension to an unbounded dimension. The high-dimensional torus configuration space (HTCS) is presented to describe the bounded-unbounded dimensions hybrid property of the IR-Robot’s configuration space. Additionally, an IR-RRT* algorithm is proposed to conduct path-planning in HTCS. The experimental results in simulation and the real world demonstrate the feasibility and superiority of the IR-Robot in path-following and path-planning tasks.