Coordinated Planning Methodology for Semi-free-floating Dual-arm Space Robots
- Paper ID
97701
- DOI
- author
- company
Harbin Institute of Technology; Research Center of Satellite Technology, Harbin Institute of Technology;
- country
China
- year
2025
- abstract
With the rapid development of space technology, large-scale space systems, such as Mars bases and space solar power stations, have been proposed extensively. However, space is not a simple environment, and to reduce the risks in construction and improve efficiency, it has been suggested that robots be used to replace astronauts. This places significant demands on the function and performance of the proposed space robots. Unlike robots on the ground, the robots in space work in a microgravity environment, which means the base can move under control or freely. To minimize fuel consumption due to the thrusters and extend the working lifespan, the base of a space robot is typically set uncontrolled during the execution of operational tasks, in other words, free-floating. The traditional planning strategy is to utilize the assumptions of momentum and angular momentum conservation, and the system's dimensionality is reduced by substituting base motion with joint motion. But in practical applications, the end-effector of the robot inevitably comes into contact with other objects, thereby generating external forces. Under this circumstance, the assumptions of momentum and angular momentum conservation are no longer available. This condition, where the base is free, but the end-effector is subject to external forces, is defined as semi-free-floating in this paper. Furthermore, although the base motion is free, the base attitude must still satisfy certain constraints due to the pointing requirements of the manipulator’s sensors, antennas, and other components during operation. This paper focuses on coordinated planning methodology for semi-free-floating dual-arm space robots. Firstly, the kinematics and dynamics model of the semi-free-floating space manipulator is derived, where the base motion is eliminated at the acceleration level. Secondly, based on the recursive Jacobian method, a trajectory planning framework for semi-free-floating space manipulators is proposed. A novel artificial potential function is also proposed to describe the attitude constraints of the base. Then based on null-space theory, the base pointing constraints and self-collision avoidance constraints are incorporated into the planning framework. Finally, to track the designed end-effector trajectory, a simulation for path planning is conducted using the proposed method. The results show that the proposed path planning method can track the desired end-effector trajectory effectively and satisfy different constraints at the same time. Since the proposed method in this paper does not rely on the assumptions of momentum conservation, it is still available when the end-effector is subjected to external forces.