Adaptive fixed-time fuzzy fault-tolerant cooperative spiral-diving guidance law with initial state-independent prescribed performance

This paper proposes a novel performance guaranteed fixed-time fuzzy adaptive fault-tolerant cooperative spiral-diving guidance law for a group of flight vehicles subject to system internal uncertainties, actuator faults, and external disturbances simultaneously. Firstly, based on the analysis of the spiral-diving terminal guidance process, a novel set of guidance dynamic equations, which is different from the traditional line-of-sight angle equations but suitable for the design of a cooperative spiral guidance law, is established. Thereafter, by designing a novel Initial State-Independent Fixed-Time Prescribed Performance Function (ISIFTPPF), the time-to-go free virtual guidance law that can ensure prescribed performance in spite of any initial condition is developed to generate spiral maneuvers. Subsequently, the fixed-time adaptive guidance law based on the auxiliary subsystem is designed, ensuring that actuator saturation constraints can be satisfied and the unknown disturbances as well as actuator faults can be effectively handled. It should be noted that the proposed method is a low-complexity hierarchical spiral guidance scheme that can remarkably reduce the consumption of computational resources. Theoretical analysis illustrates that the closed-loop system is practically fixed-time stable, and the tracking errors will converge within the pre-given boundaries. Finally, the effectiveness, superiority, and practical application potential of the proposed cooperative guidance method are demonstrated by several numerical simulations.