Modeling of a free-flying space robot manipulator in contact with a target satellite

This paper presents a unified control-oriented modeling of a free-flying space robot interacting with a target satellite. The purpose of the modeling is to design a controller to track motion trajectory while regulating the force interaction between the space robot and the target satellite. Many space missions can benefit from such a modeling system, for example, autonomous docking of satellites, rescuing satellites, and satellite servicing, where it is vital to limit the contact force during the robotic operation. A unified dynamics model is developed by combining equations of motions of the space-robot and the target satellite all together with the constraint equations of the contact geometry and those of the conservation of linear momentum and angular momentum. The former constraint is imposed due to constrained motion of the space-robot end-effecter, while the later exists because all force/moment, including the contact force and joint torques, are considered as internal force/moment for the combined system of the space robot and the target satellite. Finally, simulation is demonstrated by using a PD controller to verify the analytical results