Three-Dimensional Sliding Mode Guidance Law Based on Variable Universe Fuzzy Control

This work investigates guidance problem in three-dimensional coordinates with impact angle constraint, speed of system reaching sliding surface and external disturbance, and proposes a fuzzy sliding mode guidance method with time-varying gain parameter adjustment. Specifically, with the segmented sliding mode control, a guidance law which can control the error between the actual impact angle and the desired value to zero, is proposed in this study. This method can solve the slow convergence problem when the sliding mode approaches zero. To speed up the convergence process, some fuzzy rules are formulated by analyzing the interference, and the influence of the error is compensated. Moreover, the variable universe factors are designed to make the parameter variables cover more fuzzy rules. It can be seen from the simulation results, the design of segmented sliding mode can reduce the time that system reaches the sliding surface, the fuzzy sliding mode control can accelerate the convergence rate without affecting the guidance performance. After the introduction of noise, the fuzzy sliding mode control can effectively reduce the interference affect, ensure the stability after sliding mode converges to zero, reduce the overload requirement of the aircraft, and verify the rationality of the designed algorithm.