A Nonlinear Observer-Based Approach to Robust Cooperative Tracking for Heterogeneous Spacecraft Attitude Control and Formation Applications

This article proposes a nonlinear observer-based approach to address the robust cooperative tracking problem and application for heterogeneous spacecraft systems. By introducing appropriate assumptions, a weight average estimation is proposed to construct a class of distributed nonlinear observers for heterogeneous spacecraft systems with a target whose dynamics are available only to a few chasers. By synthesizing the observer dynamics among the neighbors, a novel cooperative tracking controller is developed to address nonidentical parameters both in model uncertainties and nonlinear dynamics. Then, the robust consensus tracking problem can be solved if the cooperative behaviors between the chasers and their observers can be achieved synchronically. A special case of the identical model uncertainty and nonlinear dynamics scenario is also discussed. As applications of the proposed nonlinear observer-based approaches, the controller and observer designs of heterogeneous spacecraft attitude control and formation flying systems are revisited. Numerical simulations with a nonlinear dynamic model of spacecraft attitude control and formation flying systems demonstrate the effectiveness of the proposed approaches.