Partial-State Feedback Consensus Model Reference Adaptive Control for Nonaffine Drag-Free Spacecraft Inner-Formation System

This article proposes a consensus control approach for the inner-formation system (IFS) containing the drag-free spacecraft and two cubic test masses. Considering the control problem caused by immeasurable states of the velocities in the system, a partial-state feedback control scheme is investigated, and the consensus model reference model reference adaptive control (MRAC) is established to adaptively actuate the IFS to a stable reference model in consideration of parameter uncertainties. Concerning the nonaffine electrostatic actuation and suspension of the test masses, the fuzzy logic system is used to estimate the unknown nonlinearities. By combining the fuzzy logic-based estimator and adaptive consensus controller, the partial-state feedback model reference adaptive consensus control scheme is developed for the nonaffine IFS. Theoretical analysis proves the uniformly ultimately boundedness of each closed-loop signal in the formation system, the control performance is verified by the numerical simulations of the drag-free spacecraft IFS.