Abstract
This article investigates a novel fuzzy-approximation-based nonaffine control strategy for a flexible air-breathing hypersonic vehicle (FHV). Firstly, the nonaffine models are decomposed into an altitude subsystem and a velocity subsystem, and the nonaffine dynamics of the subsystems are processed by using low-pass filters. For the unknown functions and uncertainties in each subsystem, fuzzy approximators are used to approximate the total uncertainties, and norm estimation approach is introduced to reduce the computational complexity of the algorithm. Aiming at the saturation problem of actuator, a saturation auxiliary system is designed to transform the original control problem with input constraints into a new control problem without input constraints. Finally, the superiority of the proposed method is verified by simulation.
Highlights
Air-breathing hypersonic vehicle (AHV) is a kind of highvelocity aircraft flying at more than 5 times the speed of sound and cruising at an altitude in the near space
In the control theory, flexible air-breathing hypersonic vehicle (FHV) has the characteristics of strong nonlinearity, strong coupling, fast time-varying, and uncertainty, which make FHV extremely sensitive to flight attitude in dynamic characteristics, and the design of the FHV control system is subject to many constraints [2,3,4]
(2) For each subsystem of FHV, only a fuzzy approximator is introduced to approximate the total uncertainties in the subsystem, which reduces the computational complexity of the system on the basis of ensuring the robustness of the controller
Summary
Air-breathing hypersonic vehicle (AHV) is a kind of highvelocity aircraft flying at more than 5 times the speed of sound and cruising at an altitude in the near space. Low-pass filters are used to solve the nonaffine dynamics of FHV (2) For each subsystem of FHV, only a fuzzy approximator is introduced to approximate the total uncertainties in the subsystem, which reduces the computational complexity of the system on the basis of ensuring the robustness of the controller. The norm estimation approach is introduced in this article to ensure the computational speed compared with the previous fuzzy control method (3) Compared with the traditional back-stepping control method, all the virtual controllers proposed in this article are only used as intermediate variables for the stability analysis of the system and do not participate in the final solution and execution (4) An auxiliary system is introduced to transform the original control problem with input constraints into a new control problem without input constraints to solve the transient saturation problem in the control input
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