Nonlinear Proportional Derivative Control for Rigid Spacecraft via MRPs

In this paper, the unwinding problem in attitude tracking for rigid spacecraft is studied. A nonlinear proportional-derivative-type attitude tracking control strategy based on MRPs is developed. The key feature of the obtained closed-loop system is its achievement of two stable equilibria. It is proven that the closed-loop system is almost globally asymptotically stable. Moreover, two adjustable subsets of the attraction domains corresponding to each stable equilibrium are specified. It is demonstrated through simulations that the unwinding challenge is tackled during spacecraft attitude tracking by employing the proposed control strategy.