A novel approach to the simulation of on-orbit rendezvous and docking maneuvers in a laboratory environment through the aid of an anthropomorphic robotic arm

Orbital robotics, due to the unfriendly environment (radiation, micro-gravity, thermal stresses, etc.) poses unique challenges to robot and robot algorithms, and sets the need for new and innovative autonomous systems. The design of servicing operations and devices is nowadays one of the most important research field in space robotics. Servicing operations range from regular inspection to the upgrade of components and re-fuelling. It is immediate to notice that, regardless of the operation to be carried out, the success is strictly linked to the way in which the chaser and the target satellites move and interact with respect to each other. The importance of relative motion for rendezvous and docking operations, calls for an approriate laboratory facility able to reproduce orbital conditions. This can be achieved only with a robotic structure that simulates the target and chaser´s kinematics and dynamics. In this paper, a complete approach to the problem is presented, from the kinematic analysis to the modelling of the impact. In particular, a spring-dashpot model was chosen for the contact simulation, and a virtual-force control system has been adopted. Then, by considering the system´s stability, we extracted the analytical expressions that link the performances of the facility with the range of orbital systems that can be simulated. Furthermore, with the aid of a SimMechanics® numerical model, we inspected the performances of three different control strategies for the movimentation of the robot.