Adaptive Fuzzy Control of Spacecraft Proximity Operations Using Hierarchical Fuzzy Systems

The six-degrees-of-freedom relative motion control of a chaser spacecraft approaching a free tumbling target in deep space is investigated in this paper. In view of unknown model uncertainties and complex dynamic couplings in the dynamical model, a direct adaptive fuzzy nonlinear controller is constructed by using fuzzy logic systems to approximate the uncertainties and couplings, where the parameter vectors of fuzzy systems are estimated online by using a projection-based adaptive control method. Due to the great dimension of the system variables, hierarchical fuzzy logic systems are employed in the fuzzy control to reduce the amount of fuzzy rules and alleviate the online computation burden in the proposed control algorithm. It is proved that tracking errors of the chaser spacecraft and adaptive parameters of the fuzzy systems are uniformly ultimately bounded. Numerical simulations are performed to demonstrate the performance of the proposed control strategy.