Equivalence model based discrete sliding mode control method for hypersonic velocity aircraft

Abstract

The invention discloses an equivalence model based discrete sliding mode control method for a hypersonic velocity aircraft and belongs to the field of aircraft control. The method is used for solving the technical problem that discrete adaptive control of existing hypersonic velocity aircrafts is difficult to implement in engineering. The method comprises the steps of firstly, converting a height subsystem model of the hypersonic velocity aircraft into a strict-feedback form, further establishing a discrete strict-feedback form of an original system through an Euler method, considering the causal sequence of the system, establishing an equivalence model of the original system, using the equivalence model to analyze historical information of the uncertainty of the system, using the historical information for design of a sliding mode controller, and designing the controller according to backstepping method strategies through error feedback by using a nominal system. According to the method, characteristics of computer control are combined, non-causal problems are effectively avoided through the controller which is obtained through model conversion, and the height and the velocity of the hypersonic velocity aircraft can be tracked without adaptive estimation strategies which are complex in design.

Description

technical field [0001] The invention relates to a control method of a hypersonic aircraft, in particular to a discrete sliding mode control method for a hypersonic aircraft based on an equivalent model, and belongs to the field of aircraft control. Background technique [0002] Due to its outstanding flight capability, hypersonic aircraft makes global real-time strike possible, so it has attracted widespread attention at home and abroad; NASA X-43A test flight successfully confirmed the feasibility of this technology; affected by its own complex dynamic characteristics and the airframe With the integrated design of the engine, the coupling between the elastic body, propulsion system and structural dynamics of the hypersonic vehicle is stronger, and the nonlinearity of the model is also higher; sensitive. [0003] The control of hypersonic vehicles is mostly concentrated in the continuous domain; with the development of computer technology, the control system of hypersonic v...

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Problems solved by technology

[0004] The article "Back-stepping-Based Discrete Controller Design for Hypersonic Vehicle" (Gao Daoxiang, Sun Zengqi, Du Tianrong, "Control and Decision-Making", Volume 24, Issue 3, 2009) adopts the second method to transform the altitude subsystem into a four-dimensional First-order model, by designing virtual control variables (track angle, pitch angle, and pitch angular velocity) to control the previous state quantity, and finally use the rudder angle to control the pitch angular velocity; this method only uses the information of the current moment and the next moment , the nominal system is used to approximate the future information of the required virtual control quantity; due to the uncertainty of the system dynamics parameters, the future information of the system state cannot be known, and the future of the virtual control quantity cannot be obtained according to the relevant expression Information, there are non-causal problems, it is difficult to realize engineering

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