Model Predictive Control to Autonomously Approach a Failed Spacecraft

Abstract

In this study, a model predictive control (MPC) method is developed for a servicer spacecraft autonomously approaching a tumbling failed spacecraft at an ultraclose range. Flight safety and collision avoidance are basic requirements during the approach. Two types of a failed spacecraft with complex configurations are considered, and a double-ellipsoid composite envelope strategy is designed to model their keep-out zones. Given the keep-out zone of the servicer, two expanded ellipsoids are subsequently introduced to determine the collision and sufficient conditions for collision avoidance are derived by using the form of concave constraint. The tumbling motion of the target is considered, and a CW-based translational dynamics and derived attitude dynamics of the target are formulated to predict the motion of the docking point and keep-out zone. The MPC is formulated to drive the servicer tracking the docking point with collision avoidance and handle constraints including control input saturation and relative velocity bound. Convexification of the collision avoidance constraint and sequential convex programming are adopted for the implementation of MPC. Scenarios on the servicer with different initial positions approaching the target with different angular velocities are simulated, and the simulation results indicate that the proposed MPC method is effective.

Coupled position and attitude control of a servicer spacecraft in rendezvous with an orbiting target

“…According to the simulation results shown in 14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64, 65, 66, 67, 68 and 69, it can be claimed the designed controllers were successful in their mission to pursue the target.…”

“…But designing predictive control for nonlinear systems will come with some sophistication. In this field, an MPC approach is being developed by 24 for an autonomous servicer spacecraft approaching a tumbling target at an ultra-close distance. The target was considered to behave in a deterministic manner.…”