Optical-integral sliding-mode attitude control method of reentry vehicle and controller

Abstract

The invention relates to an optical integral sliding-mode attitude control method of a reentry vehicle and a controller, and belongs to the technical field of vehicle control. The optical-integral sliding-mode attitude control method comprises the following steps of: firstly designing an SDRE (State-dependent Riccati Equation) nominal attitude control law according to a nominal model of the vehicle, and enabling the performance of a nominal system to meet the proposed optimal indexes; then considering the uncertainty of the system, designing an integral sliding-mode control law on the basis of the SDRE nominal attitude control law, enabling the system to have robustness while meeting the performance index requirement; and in order to weaken the buffeting, introducing a design idea of a second-order sliding mode and enabling the output of the controller to be smoother. The attitude controller designed by the invention not only can guarantee the expected indexes, but also has better robustness.

Description

technical field [0001] The invention relates to an optimal integral sliding mode attitude control method and a controller of a reentry aircraft, belonging to the technical field of aircraft control. Background technique [0002] During the unpowered re-entry flight of the aircraft, the air density and aircraft speed change greatly, the dynamic parameters change drastically, and the coupling between channels is very serious, showing strong multivariable coupling and nonlinearity, accompanied by other unknown disturbances and Therefore, it is very critical to design a robust attitude controller for fast time-varying and highly uncertain systems. [0003] At present, according to the characteristics of reentry flight, many scholars have proposed different attitude controllers, such as robust controllers, adaptive controllers, optimal controllers, and sliding mode controllers. Based on the state-dependent Riccati equation (SDRE) method, an optimal control law design method for ...

AI Technical Summary

Problems solved by technology

One idea of ​​combining optimal control theory with sliding mode control theory is to apply linear quadratic optimal control theory to the design of sliding mode surfaces, which is applied to uncertain linear systems to improve the performance of LQR, however For nonlinear systems, when performing sliding mode surface optimization, it will lead to a two-point boundary value problem that is difficult to solve; another idea is to use the sliding variable structure control theory to robustly design the optimal controller, and use the integral sliding mode One part of the control law is the LQR control law determined for the nominal linear system, and the other part is the integral sliding mode control, which ensures the robustness of the system. Stickiness introduces chattering of sliding mode

Chattering can be weakened by using a boundary layer, but at this time the sliding mode surface is limited to a small area, and the accessibility of the sliding mode cannot be proved, which makes the system performance deviate from the optimal index

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