Observer-Based Fixed-Time Composite Adaptive Fuzzy Consensus Control for Multiple Spacecraft

This article investigates the observer-based composite adaptive fuzzy fixed-time consensus control issue for multiple spacecraft attitude system with unmeasurable states. Fuzzy logic systems (FLSs) are applied to tackle unknown nonlinearity in spacecraft system. Based on FLSs, a fuzzy observer is constructed for the estimation of unmeasurable states. Meanwhile, to improve the approximation performance of FLSs, a fixed-time serial-parallel estimation model is designed. The quadratic function is employed to address the potential singularity issue in the derivative of the virtual controller. In addition, a filter with fixed-time stable is introduced to avert the complex explosion issue. To this end, a fixed-time composite adaptive consensus control scheme is designed by considering the prediction error of the serial-parallel estimation model. Under the proposed scheme, the boundedness of all signals in the closed-loop system is ensured and the tracking error converges to a small neighborhood of zero within a fixed time. Eventually, the feasibility of the proposed control scheme is illustrated by the simulation results.