Nonlinear Passivity-Based Adaptive Control of Spacecraft Formation Flying

In this paper, a nonlinear output feedback adaptive control system for spacecraft formation flying is developed. Specifically, the proposed approach addresses the problem of controlling a chaser spacecraft such that it tracks a desired relative trajectory with respect to the target spacecraft, regardless of unknown parameters and disturbance forces. Making use of passivity results, the closed-loop stability of the adaptive system is guaranteed via Lyapunov direct method and LaSalle's invariance principle arguments. Simulation results for a projected circular formation example are provided to illustrate the increased performance and robustness of the proposed adaptive controller compared to a conventional non-adaptive proportional-derivative control law.