Real-time 6dof Terminal Guidance for Autonomous Spacecraft Capture Free Floating Objects Using State Dependent Model Predictive Control

Abstract: This paper investigates the optimal rendezvous with power-limited propulsion systems and collision avoidance. A 26-state dynamic model is established including both translational and rotational dynamics. This model is effective for describing autonomous rendezvous with both a three-axis attitude stabilized target and a tumbling one. Collisions are prevented through setting a safety sphere centered at the mass center of the target. Two rendezvous scenarios in actual missions are considered in this paper. The first case is to drive the chaser vehicle to rendezvous with a three-axis attitude stabilized target. A light-of-sight (LOS) tetrahedral path constraint is imposed for vision-based sensing and safety considerations. The second is to rendezvous with a tumbling target with an arbitrary docking port. The novel concept of tumbling plane is introduced to describe the tumbling motion. Then, the optimal-fuel rendezvous is transformed into a quadratic programming problem (QPP) using the state dependent model predictive control (SDMPC). Numerical simulations demonstrate that the proposed method can guarantee the safety of the autonomous rendezvous and to minimize the fuel consumption. In addition, this algorithm can be numerically solved rapidly.