An Adaptive Fuzzy Sliding-mode Technique for Attitude Control of Launch Vehicle

Launch vehicle attitude control system is a very complex system with real parameter uncertainties and external disturbances in the process of flight for launch vehicle. This paper presents a novel adaptive fuzzy sliding-mode control (AFSMC) system for high-precision attitude control of launch vehicle. Considering the structure perturbation and uncertain external disturbances in the process of flight, the proposed AFSMC system is designed via the approximation ability of a fuzzy logic system to mimic the good behavior of a total sliding-mode control (TSMC) system, which is designed without the reaching phase of a conventional sliding-mode control (SMC). In the proposed system, a priori knowledge of the system information is not required. Moreover, the gradually increasing estimate upper bound, which may induce the control effort into saturation and excite unstable system dynamics in serious chattering phenomena in some conditions, would not exist. In the proposed controller, the adaptive tuning algorithms are developed in the sense of the Lyapunov stability theorem, so that system-tracking stability can be guaranteed. Finally, Simulation results show that the proposed control scheme is effective for launch vehicle attitude control system and has stronger robustness for external disturbances.