Fuzzy adaptive fault tolerant IGC method for STT missiles with time-varying actuator faults and multisource uncertainties

This paper studies the integrated guidance and control (IGC) problem for a class of skid-to-turn (STT) missiles subjected to rapidly changing actuator failures and coupled multisource uncertainties. Meanwhile, during interception, the target is allowed to possess unknown and changeable maneuver accelerations. By analyzing the dominating factors in the IGC system, a nonlinear uncertain strict-feedback system suffering from matched and mismatched uncertainties is utilized to describe the IGC dynamics. Furthermore, for each subsystem, the control gain functions and their boundaries are assumed unknown, which make it difficult to design the controllers. By using a hyperbolic tangent function and estimating the bounds of the lumped disturbances, the time-varying multisource uncertainties can be handled. To compensate the unknown nonlinearities existing in the IGC system, several fuzzy logic systems are established. Furthermore, a number of reciprocal adaptive laws are developed such that unwanted effects caused by the unknown control gain functions and changing actuator gain faults can be surmounted. As a result, a novel fault tolerant IGC structure is constructed and satisfactory hit-to-kill interception performance can be obtained. Finally, the numerical simulations are provided to verify the validity and advantage of the proposed method.