Robust fixed-time flight controller for a dual-system convertible UAV in the cruise mode

This paper investigates the attitude tracking control problem for the cruise mode of a dual-system convertible unmanned aerial vehicle(UAV)in the presence of parameter uncertainties,unmodeled uncertainties and wind disturbances.First,a fixed-time disturbance observer(FXDO)based on the bi-limit homogeneity theory is designed to estimate the lumped disturbance of the convertible UAV model.Then,a fixed-time integral sliding mode control(FXISMC)is combined with the FXDO to achieve strong robustness and chattering reduction.Bi-limit homogeneity theory and Lyapunov theory are applied to provide detailed proof of the fixed-time stability.Finally,numerical simulation experimental results verify the robustness of the proposed algorithm to model parameter uncertainties and wind disturbances.In addition,the proposed algorithm is deployed in a open-source UAV autopilot and its effectiveness is further demonstrated by hardware-in-the-loop experimental results.

Research on Teaching Methods of Flight Control Principles

With the rapid development of China’s civil aviation industry,the teaching method of operating knowledge of flight principles has changed greatly,which creates a good implementation environment to improve the safety of civil aviation in our country.At present,the main training content of air route transport pilots in China is basic aviation theory,initial flight training,airline modification,etc.The principles of flight control are an important part of basic aviation theoretical knowledge training,which will involve a large number of flight technology training content,instructors will also be based on the pilot type.Teaching flight control theory and practical knowledge requires relatively high theoretical learning ability of students,and the learning effect of this part of theoretical knowledge will directly affect the quality of subsequent learning,but also directly affect the effectiveness of flight training.This paper focuses on the analysis of the basic concepts of flight control,studies the existing problems in the teaching of flight control principles,summarizes the teaching measures of flight control principles,aiming to provide a reference to teaching personnel.

Novel robust fault diagnosis method for flight control systems

A novel robust fault diagnosis scheme, which possesses fault estimate capability as well as fault diagnosis property, is proposed. The scheme is developed based on a suitable combination of the adaptive multiple model （AMM） and unknown input observer （UIO）. The main idea of the proposed scheme stems from the fact that the actuator Lock-in-Place fault is unknown （when and where the actuator gets locked are unknown）, and multiple models are used to describe different fault scenarios, then a bank of unknown input observers are designed to implement the disturbance de-coupling. According to Lyapunov theory, proof of the robustness of the newly developed scheme in the presence of faults and disturbances is derived. Numerical simulation results on an aircraft example show satisfactory performance of the proposed algorithm.

Flight Control System of Unmanned Aerial Vehicle

To date unmanned aerial system(UAS)technologies have attracted more and more attention from countries in the world.Unmanned aerial vehicles(UAVs)play an important role in reconnaissance,surveillance,and target tracking within military and civil fields.Here one briefly introduces the development of UAVs,and reviews its various subsystems including autopilot,ground station,mission planning and management subsystem,navigation system and so on.Furthermore,an overview is provided for advanced design methods of UAVs control system,including the linear feedback control,adaptive and nonlinear control,and intelligent control techniques.Finally,the future of UAVs flight control techniques is forecasted.

Dynamic Surface Control with Nonlinear Disturbance Observer for Uncertain Flight Dynamic System

A new robust control method of a nonlinear flight dynamic system with aerodynamic coefficients and external disturbance has been proposed.The proposed control system is a combination of the dynamic surface control(DSC)and the nonlinear disturbance observer(NDO).DSC technique provides the ability to overcome the″explosion of complexity″problem in backstepping control.NDO is adopted to observe the uncertainties in nonlinear flight dynamic system.It has been proved that the proposed design method can guarantee uniformly ultimately boundedness of all the signals in the closed-loop system by Lyapunov stability theorem.Finally,simulation results show that the proposed controller provides better performance than the traditional nonlinear controller.

New robust fault-tolerant controller for self-repairing flight control systems

A new robust fault-tolerant controller scheme integrating a main controller and a compensator for the self-repairing flight control system is discussed.The main controller is designed for high performance of the original faultless system.The compensating controller can be seen as a standalone loop added to the system to compensate the effects of fault guaranteeing the stability of the system.A design method is proposed using nonlinear dynamic inverse control as the main controller and nonlinear extended state observer-based compensator.The stability of the whole closed-loop system is analyzed.Feasibility and validity of the new controller is demonstrated with an aircraft simulation example.

A fault-tolerant control method for distributed flight control system facing wing damage

With the strong battlefield application environment of the next generation fighter,based on the design of distributed vehicle management system,a fault diagnosis and fault-tolerant control(FTC)method for wing surface damage is proposed in this paper.Aiming at three kinds of wing damage modes,this paper proposes a diagnosis method based on the fault decision tree and forms a fault decision tree for wing damage from the aspects of sample database construction,feature parameter extraction,and fault decision tree construction.Based on the fault diagnosis results,the longitudinal control law based on dynamic inverse and the lateral-directional robust control laws based on linear quadratic regulator(LQR)are proposed.From the simulation examples,the fault diagnosis algorithm based on the decision tree can complete the judgment of three wing surface damage modes within 2 ms,and the FTC law can make the fighter quickly return to a stable flight state after a short transient of 1 s,which achieves the fault-tolerant goal.

HIERARCHICAL APPROACH AND ITS APPLICATION TO INTEGRATED FLIGHT／PROPULSION CONTROL SYSTEM

A new model and design method for integrated flight/propulsion control system are presented. To avoid solving higher order Riccati equations, a hierarchical optimization method is developed based on structure perturbation. In the new method, designing of a linear (luadrate regulator (LQR) is divided into two steps: (1 ) computingfeedback gain matrix of individual subsystem, while the association among these subsystems is omittd, and (2) according to the optimization method of LoR, computing thecompensation gain matrix for each subsystem using input perturbation approach. Simulation and application show that not only the results of the new method is as good as that ofan ordinary LQR, but also the efficiency is much higher than that of LQR.

Interval Criterion of Robust Stability for Nonlinear System and Its Application to Flight Control

Robust stability for a series of nonlinear systems is presented in this paper. Through different region descriptions, the problem of stability for a complex nonlinear system is transformed into ones of the robust stabilities of several linear time-invariant systems. To get useful robust stability conditions, an expression for interval system is given, and the relationship between the internal stability and low- or supper-bound stability of interval systems is discussed. Thus, the polynomial matrix inequality for the determination of system robust stability is developed. Based on the equivalency transformation of the inequality, the solvable condition of the inequality is obtained. By means of the condition, robust stability theorem for interval systems is presented and a new design method of feedback control for nonlinear system is achieved. Applications to flight controller design show that the new method is efficient for uncertain system design.

ADAPTIVE FLIGHT CONTROL SYSTEM OF ARMED HELICOPTER USING WAVELET NEURAL NETWORK METHOD

A discussion is devoted to the design of an adaptive flight control system of the armed helicopter using wavelet neural network method. Firstly, the control loop of the attitude angle is designed with a dynamic inversion scheme in a quick loop and a slow loop. respectively. Then, in order to compensate the error caused by dynamic inversion, the adaptive flight control system of the armed helicopter using wavelet neural network method is put forward, so the BP wavelet neural network and the Lyapunov stable wavelet neural network are used to design the helicopter flight control system. Finally, the typical maneuver flight is simulated to demonstrate its validity and effectiveness. Result proves that the wavelet neural network has an engineering practical value and the effect of WNN is good.

RECONFIGURABLE FLIGHT CONTROL SYSTEMS DESIGN

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NONLINEAR DYNAMIC INVERSION CONTROL WITH ADAPTIVE COMPENSATION FOR FLIGHT CONTROL SYSTEM

A type of nonlinear dynamic inversion control with adaptive compensation is proposed in order to overcome its over sensitivity to parameter uncertainty and disturbance for flight control system using nonlinear dynamic inversion. This control strategy is different from the general strategy of a nonlinear adaptive control by taking into consideration both parameter uncertainty and external disturbance, the two major uncertain forms in flight control. Finally, an analysis of the stabilily of this control structure is given.

APPLICATIONOFNEURALNETWORKTOFLIGHTCONTROLSYSTEMDESIGN

Artificial neural network (ANN) has a great capability of self learning. The application of neural network to flight controller design can get good result. This paper studies the method of choosing controller parameters using neural network with Back Propagation (B P) algorithm. Design and simulation results show that this method can be used in flight control system design.

DESIGNING REDUCED-ORDER CONTROLLERS OF MIXEDSENSITIVITY PROBLEM FOR FLIGHT CONTROL SYSTEMS

Based on linear matrix inequalities (LMI), the design method of reduced order controllers of mixed sensitivity problem is studied for flight control systems. It is shown that there exists a controller with order not greater than the difference between the generalized plant order and the number of independent control variables, if the mixed sensitivity problem is solvable for strict regular flight control plants. The proof is constructive, and an approach to design such a controller can be obtained in terms of a pair of feasible solution to the well known 3 LMI. Finally, an example of mixed sensitivity problem for a flight control system is given to demonstrate practice of the approach.

New Stability Condition of T-S Fuzzy Systems and Design of Robust Flight Control Principle

Unlike the previous research works analyzing the stability of the T-S （Takagi-Sugeno） fuzzy model, an extension on the stability condition of T-S fuzzy systems with a different strategy is provided. In the strategy a new variable, which is relative to the grade of fuzzy membership function, is introduced to the stability analysis and a new stability conclusion is deduced. The definition of stability condition in this paper is different from previous works, though they are similar in form. With the proposed method, the simulation in flight control law shows a better effectiveness.

Networked guaranteed cost PID attitude tracking control of a laboratory flight system

This paper investigates the networked flight control system for a laboratory 3 degrees of freedom (3-DOF) helicopter,and presents a novel networked guaranteed cost proportion-integration-differentiation (PID) attitude tracking control method with consideration of time-varying delay and packet dropouts.As the 3-DOF helicopter characteristics of multi-input multi-output (MIMO),channel coupling,and nonlinearity,a genera linear time delay system is modeled by analyzing the motions on elevation,pitch,and travel axis.By using the reciprocal convex approach,the free weight matrix,and the cone complementarity linearization (CCL) method,the PID tracking controller parameters can be designed if the related linear matrix inequalities (LMIs) are feasible.Finally,a practical experiment of laboratory 3-DOF helicopter is given,and the experimental results show that the proposed method is effective.

STUDIES ON AIRCRAFT TOTAL ENERGY FLIGHT CONTROL SYSTEM：NONLINEAR SYSTEM INTEGRATION AND SIMULATION

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THE EIGENVALUE SENSITIVITY ANALYSIS AND DESIGN FOR INTEGRATED FLIGHT/PROPULSION CONTROL SYSTEM

In this paper, sensitivity approaches are taken to analyze and design an integrated flight propulsion control system where the interaction between subsystems direitly affects the stability property and handling performances of the aircraft. The eigenvalue sen sitivity approach is employed to study the effect of coupling parameters on system stability and gain sensitivity approach is used to direct the reduced states feedback suboptimal control system design. Simulation results show that the integrated flight propulsion control system designed by sensitivity approaches is of good performance.

A REVERSED-FRAME NORMALIZATION DESIGN OF ROBUST FLIGHT CONTROL SYSTEM

In this paper, a discussion is devoted to the theory and method of a reversed-frame normalization design to robust flight control system. The robust stability theory of the normal transfer function matrix with the same characteristic gain loci is proved. An example of flight control system design shows the application and advantage of this method.

MATHEMATICAL MODEL OF SELF-REPAIRING FLIGHT CONTROL

The most prospective method for certain structural failures and damages that cannot employ redundancy is self-repairing techniques, to ensure especially the maximum flight safety. Based on the characters of self-repairing aircraft, this paper states some basic assumptions of the self-repairing aircraft, and puts forward some special new conceptions concerning the self-repairing aircraft: control input, operating input, command input, repair input and operating and control factor as well as their relationships. Thus it provides a simple and reliable mathematical model structure for the research on the self-repairing control of the aircraft.