HQP-Based Obstacle Avoidance Motion Planning and Control of On-Orbit Redundant Manipulators

On-orbit redundant manipulators, owing to their flexibility and fault tolerance, are well-suited for performing tasks in confined environments. However, complex space environments introduce significant challenges in obstacle avoidance, motion planning, and control. This paper focuses on a seven-degree-of-freedom (7-DoF) manipulator of the space station remote manipulator system (SSRMS) type, addressing its kinematics and obstacle avoidance in motion planning and control. Initially, a 3D model of the redundant manipulator was developed, and its forward kinematics were established using the Denavit-Hartenberg (D-H) method. The Jacobian matrix was computed through the vector product method. Inverse kinematics were subsequently resolved using a redundancy resolution approach based on quadratic programming (QP), and a joint velocity-based motion planning strategy was designed to ensure high-precision end-effector trajectory tracking. Additionally, a configuration optimization function was introduced to address singularity avoidance and joint limit constraints using the gradient descent method. To prioritize tasks, dual-trajectory tracking was implemented using hierarchical quadratic programming (HQP), enabling the manipulator to effectively avoid obstacles. Finally, several simulations were conducted to validate the effectiveness of the proposed methods.