Aircraft lateral-directional fault-tolerant control and reconstruction method under failure of aileron control surface

Abstract

The application discloses a kind of aileron surface failure under airplane lateral fault-tolerant control and reconstruction method, belong to aircraft fault diagnosis field.The application discloses a kind of aileron surface failure under airplane lateral fault-tolerant control and reconstruction method, for fixed-wing aircraft actuator common fault, an active fault-tolerant control scheme of integrated fault estimation algorithm and reconfigurable control is presented, and an integrated fault-tolerant control strategy based on multi-model adaptive unknown input observer and model reference adaptive control method combination is designed.To realize the fault estimation of flight control system, a robust unknown input observer is designed to estimate the actuator additive fault and multiplicative fault.According to the characteristics of the flight control system fault model, the additive fault is treated as external disturbance, and the multiplicative fault is used to design the adaptive law.Finally, the effectiveness of the proposed integrated fault-tolerant control strategy is verified through actuator stuck fault, failure fault and offset fault.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aircraft fault diagnosis, and particularly relates to a horizontal and lateral fault-tolerant control and reconstruction method for an airplane under failure of aileron surfaces. BACKGROUND

[0002] With the application of airplanes in various industries, flight control systems have become more complex, and people have greatly increased the requirements for safety, reliability, maintainability and survivability of airplanes. It is well known that airplanes are the most efficient implementation in transportation tasks, but inevitably, problems such as actuator failure, sensor failure and even damage to the structure of the airplane will occur. These failures and damages will cause the airplane to lose balance, accompanied by changes in aerodynamic characteristics and inertial characteristics, and also accompanied by a decrease in flight control authority. Under such a background, fault-tolerant control that can automatically tolerate faults has been widely applied and developed while maintaining stability and ideal performance. A fault-tolerant control system is a control system that can automatically adapt to component failures, and after a fault occurs in the system, it has the ability to maintain the stability of the overall system or to make the system in an acceptable performance state. When the aileron surface is abnormal, it will pose a serious threat to flight safety. Therefore, the research on aileron surface control and reconstruction has important significance and practical value.

[0003] Fault-tolerant control is divided into passive fault-tolerant control and active fault-tolerant control. The design of a passive fault-tolerant controller is based on the idea of robust control, and regardless of whether a fault occurs or not, an invariant controller is used to ensure that the closed-loop system is robust to a specific fault. Therefore, it can be said to be an extension of robust control. Although this method does not require a fault estimation algorithm or reconfigurable control, its fault-tolerant ability is limited. Compared with passive fault-tolerant control, the flexibility and potential prospects of active fault-tolerant control attract more researchers' attention. The role of fault estimation technology is to monitor and diagnose the system, and not as part of a fault-tolerant system. Therefore, some fault estimation methods cannot meet the needs of system controller reconstruction, and some fault estimation methods are not as perfect as designed. In order to overcome these problems, a practical active fault-tolerant control scheme integrating fault estimation algorithm and reconfigurable control is designed. At present, there are still relatively few researches on the design scheme combining fault estimation and reconfigurable control technology. The existing methods still have some defects in practical application, especially in the application of flight control systems. For example, some methods calculate the control gain to be zero; some fault-tolerant control strategies for multiplication faults cannot obtain the actual estimation value of the multiplication fault. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a horizontal and lateral fault-tolerant control and reconstruction method for an airplane under failure of aileron surfaces.

[0005] To achieve the above object, the present application adopts the following technical solutions to achieve the above object:

[0006] Aileron surface failure under the airplane horizontal flight control and reconstruction method, comprising the following steps:

[0007] Step 1: considering not containing actuator failure, using time-invariant system to build fixed-wing aircraft longitudinal motion model;

[0008] Step 2: considering the actuator additive and multiplicative failure, build fixed-wing aircraft longitudinal motion model;

[0009] Step 3: introduce the reference controller, design control law;

[0010] Step 4: based on the integrated fault-tolerant control system strategy, the controller and observer are jointly designed to form the augmented closed-loop system and the unknown input observer based on multi-model adaptive;

[0011] Step 5: the additive fault is regarded as external disturbance, and the multiplicative fault is used to design the adaptive law of the controller.

[0012] Further, the fixed-wing aircraft lateral motion model designed in step 1 is expressed by time-invariant system:

[0013]

[0014] Wherein, x(t)∈R n is the system state, u(t)∈R is the system input, y(t) is the measured output, d(t) is the external disturbance; A, B, C are constant matrices; E is the interference matrix with full column rank.

[0015] Further, the fixed-wing aircraft longitudinal motion model is built in step (2) considering the actuator additive and multiplicative failure:

[0016]

[0017] Wherein, is the additional fault value of the i-th actuator, B=(b1,b2,…,b p ), b i is the i-th column of B, L=diag[l1,l2,…,l p ], l i ∈[0,1], is the multiplicative fault; when the actuator occurs the stuck failure, is a constant, l i =0; when the actuator occurs the saturation failure, l i =0 and u max and umin These represent the maximum and minimum values ​​for actuator failure; when an actuator fails... and l i ∈(0,1).

[0018] Furthermore, in step 3, after introducing the controller, the expression for the lateral motion model of the fixed-wing aircraft (1) is transformed into:

[0019]

[0020] in, C n =[C 0], u=K x x+K c x c K x and K c This is the control factor.

[0021] Furthermore, the system matrix A of the control variables is set. c =0 and B c =I, then the control law u is:

[0022] u=K x x+K c ∫(ry)dt (4).

[0023] Furthermore, in step (4), in the integrated fault-tolerant control system strategy, the reference model is a general closed-loop flight control system with a reference controller, represented as follows:

[0024]

[0025] y m =C m x m (5)

[0026] Where, x m =[xx c ] T u m =θ r y m =y, C m =[C 0];

[0027] Since the system and the model have the same dimensions, control variables are introduced. The system model then transforms into:

[0028]

[0029] Where, x p =[xx c ]T , y p = y, C p = [C 0], C po is the system output matrix;

[0030] In the integrated fault-tolerant control system strategy, the controller and observer are jointly designed to form an augmented closed-loop system and an unknown input observer based on multi-model adaptation, the augmented closed-loop system is shown in equation (7):

[0031]

[0032] wherein, represents the observer state quantity; represents the system state estimation; is the estimated value of L, M, G, N, H are design matrices; wherein, x m = [x x c ] T , u m = θ r , y m = y, C m = [C 0];

[0033] The unknown input observer based on multi-model adaptation is shown in equation (8):

[0034]

[0035] wherein, represents the additional value of the i th to j th actuator, F = [b i ,…,b j ] represents the fault of the i th to j th actuator.

[0036] Further, in step 5, the designed controller adaptation law is:

[0037]

[0038] wherein, P mp , Γ1, Γ2, and Γ4 are all symmetric positive definite matrices; K e (0), K m (0), K f (0) and Π d (0) are initial values, K e (t), K m (t), K f (t) and Π d (t) are current values;

[0039] In the closed-loop system, the model error between the reference model and the system model is e mp = x m (t) - x p (t), and the control law of the fault-tolerant controller is:

[0040]

[0041] Substituting the closed-loop system expression (5) and the system model expression (6) into the model error expression (10), the formula (11) is obtained:

[0042]

[0043] K m , K f and Π d are values such that A m -A p -B p K m = 0, B p K f +B p = 0 and are all true, and and the gain K e are obtained, such that (A p -B p K e ) is stable.

[0044] Further, the step 6 is further included:

[0045] controlling the flight control system by the reference controller when the aircraft is in normal condition;

[0046] providing the fault estimation value to the augmented closed-loop system by the unknown input observer when there is an actuator fault.

[0047] Compared with the prior art, the present application has the following beneficial effects:

[0048] The application discloses an airplane lateral flight direction fault-tolerant control and reconstruction method under aileron surface failure, aiming at common faults of fixed-wing airplane actuators, proposes an active fault-tolerant control scheme integrating a fault estimation algorithm and a reconfigurable control, and designs an integrated fault-tolerant control strategy combining an adaptive unknown input observer based on multiple models and a model reference adaptive control method. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figure 1 is a flowchart of the method of the application;

[0050] Figure 2 is the control effect of the normal system and the fault condition under the classical control method;

[0051] Figure 3 is the control effect of the normal system and the fault condition under the control method of the application. DETAILED DESCRIPTION

[0052] In order for those skilled in the art to better understand the application scheme, the technical solutions in the embodiments of the application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the application.

[0053] It should be noted that the terms "first", "second", and the like in the specification and claims of the application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0054] In the flight control system, there are many control surfaces, the failure of control surfaces will make the flight quality and performance decline, and even cause a major disaster. In view of the failure of the aileron rudder surface of the flight control system, under the guidance of the unknown input observer and reconstruction idea, the application provides a kind of aileron rudder surface failure under the horizontal flight fault-tolerant control and reconstruction method, on the one hand, aiming at a variety of actuator faults, analyzing the information required for reconfigurable control, designing a robust unknown input observer, and realizing the estimation of actuator additive and multiplicative faults. In the design process, the restriction on the rank of the observer in the previous research is eliminated, so that the method is more suitable for application in actual system. On the other hand, in the fault-tolerant control system, the multiplicative fault is used to design the adaptive law, and the additive fault is treated as external disturbance according to the characteristics of the fault model. Finally, enough time is provided for the aircraft to continue the task or safely return.

[0055] The application will be described in further detail below in combination with the drawings:

[0056] Designing an active fault-tolerant control system requires considering the system, observer and controller together to ensure that the augmented system can work stably. From the perspective of reconfigurable control, the fault signal needs to be obtained from the fault estimation scheme as an important link in designing the control law. From the perspective of fault estimation, a fault estimation method that can provide the required information for reconfigurable control needs to be considered. Starting from this point, the application designs an integrated fault-tolerant control strategy (IFTC) based on unknown input observer (UIO) and model reference adaptive control (MRAC), as shown in Figure 1 Under normal circumstances, the reference controller controls the flight control system. When the system has actuator faults, the UIO provides accurate fault estimation values to the reconfigurable control system to ensure that the system can restore the original system function or accept a certain degree of system performance decline.

[0057] A kind of aileron rudder surface failure under the horizontal flight fault-tolerant control and reconstruction method, it includes the following steps:

[0058] Step 1: considering the case without actuator faults, the lateral motion model of fixed-wing aircraft can be represented by the following time-invariant system:

[0059]

[0060] Where x (t) ∈ R n is the system state, u (t) ∈ R is the system input, y (t) is the measured output, d (t) is the external disturbance; A, B, C are constant matrices of appropriate dimensions; E is a disturbance matrix with full column rank.

[0061] Step 2: in the case of considering actuator additive and multiplicative faults, the system (1) is transformed into the following structure:

[0062]

[0063] in, It is the additional fault value of the i-th actuator, B = (b1, b2, ..., b p ), b i Let L be the i-th column of B, and let L = diag[l1, l2, ..., l p ], l i ∈[0,1], It is a multiplicative fault; when the actuator jams, For constants, l i =0; when the actuator experiences a saturation fault, l i =0 and When the actuator fails and l i ∈(0,1);

[0064] Step 3: After introducing the reference controller, equation (1) can be written in the following form:

[0065]

[0066] in, C n =[C 0], u=K x x+K c x c K x and K c is the control coefficient, and r is the system setpoint.

[0067] Set the control variable system matrix A c =0 and B c If I = , then the control law u transforms into the following form:

[0068] u=K x x+K c ∫(ry)dt (4)

[0069] Therefore, by using a control law, the system can track control commands well without any steady-state error.

[0070] Step 4: Design of the Unknown Input Observer (UIO)

[0071] In the integrated fault-tolerant control system strategy, the reference model is a general closed-loop flight control system with a reference controller, represented as follows:

[0072]

[0073] Where, x m =[xxc ] T u m =θ r y m =y, C m =[C 0].

[0074] In integrated fault-tolerant control system strategies, since the fault-tolerant system must have the same dimensions as its model, control variables are introduced. The system model expression (5) is then transformed into the following form:

[0075]

[0076] Where, x p =[xx c ] T y p =y,

[0077] C p =[C 0], C po It is the system's measurable output matrix.

[0078] In the integrated fault-tolerant control system strategy, the controller and observer are jointly designed to form an augmented closed-loop system (Equation 7) and an unknown input observer UIO based on multi-model adaptation (Equation 8), which takes the following form:

[0079]

[0080]

[0081] in, Represents the observer state variables; This represents a system state estimate; This is an estimate of L. M, G, N, H are design matrices; where x m =[xx c ] T u m =θ r y m =y, C m =[C 0].

[0082]

[0083] in, F represents the additional value of the i-th to j-th actuators, F = [b i ,…,b jfij represents the fault of the ith to jth actuator. The unknown fault signal of the system is obtained by the UIO and provided to the control law.

[0084] Step 5: Design of Fault-tolerant Controller

[0085] The controller adaptive law is designed as:

[0086]

[0087] where P mp , Γ1, Γ2, and Γ4 are symmetric positive definite matrices; K e (0), K m (0), K f (0), and Π d (0) are initial values, K e (t), K m (t), K f (t), and Π d (t) are current values.

[0088] In the closed-loop system (5), the model error between the reference model and the system model is defined as e mp = x m (t) - x p (t), and the control law of the fault-tolerant controller is defined as follows:

[0089]

[0090] Substituting the reference model (5) and the system model (6) into the model error expression, we obtain:

[0091]

[0092] K m , K f , and Π d are selected such that A m -A p -B p K m = 0, B p K f +B p = 0, and are all true, then we can obtain and the gain K e such that (A p -B p K e ) is stable.

[0093] Embodiment:

[0094] After the actuator failure fault occurs, the classical controller cannot keep the system stable completely, resulting in great fluctuation of the system, while the integrated fault-tolerant control strategy of the application makes the system reach stability in about 3s, as shown in Figure 2 and Figure 3 .

[0095] The above is only to illustrate the technical idea of the application, and cannot limit the protection scope of the application, and any modification made according to the technical idea of the application on the basis of the technical scheme falls within the protection scope of the claims of the application.

Claims

1. A method for fault-tolerant control and reconfiguration of an aircraft in the lateral direction under aileron control surface failure, characterized in that, Includes the following steps: Step 1: Considering the case without actuator failure, construct a longitudinal motion model of a fixed-wing aircraft using a time-invariant system; Step 2: Construct a longitudinal motion model of the fixed-wing aircraft, taking into account actuator addition and multiplication faults; Step 3: Introduce a reference controller and design the control law; Step 4: Based on the integrated fault-tolerant control system strategy, the controller and observer are jointly designed to form an augmented closed-loop system and an unknown input observer based on multi-model adaptation; Step 5: Treat additive faults as external disturbances and use multiplicative faults to design the adaptive law of the controller; In step 4, the reference model constructed in the integrated fault-tolerant control system strategy is a general closed-loop flight control system with a baseline controller, represented as follows: （5） in, , , , , , ; Introducing control variables The system model then transforms into: （6） in, , , , , , , , , It is the system output matrix; In the integrated fault-tolerant control system strategy, the controller and the observer are jointly designed to form an augmented closed-loop system and an unknown input observer based on multi-model adaptation. The augmented closed-loop system is shown in equation (7): （7） in, Represents the observer state variables; This represents a system state estimate; yes The estimated value, ; For designing the matrix; where, , , , , , ; The unknown input observer based on multi-model adaptation is shown in equation (8): （8） in, Representing the i One to the first j Additional value of each actuator Representing the i One to the first j A fault in an actuator.

2. The method for fault-tolerant control and reconfiguration of aircraft lateral direction under aileron control surface failure as described in claim 1, characterized in that, The lateral motion model of the fixed-wing aircraft designed in Step 1 is represented by a time-invariant system: （1） in, It is the system status. For system input, It is the measurement output. External interference; It is a constant matrix; It is a full-rank interference matrix.

3. The method for fault-tolerant control and reconfiguration of aircraft lateral direction under aileron control surface failure as described in claim 1, characterized in that, In step 2, considering actuator addition and multiplication faults, the longitudinal motion model of the fixed-wing aircraft is constructed as follows: （2） in, It is the first Additional fault values ​​for each actuator , for The List, , , It is a multiplicative fault; when the actuator jams, It is a constant. When the actuator experiences a saturation fault, and , u max and u min These represent the maximum and minimum values ​​for actuator failure; when an actuator fails... and .

4. The method for fault-tolerant control and reconfiguration of aircraft lateral direction under aileron control surface failure as described in claim 1, characterized in that, In step 3, after introducing the controller, the expression (1) for the lateral motion model of the fixed-wing aircraft is transformed into: （3） in, , , , , and This is the control factor.

5. The method for fault-tolerant control and reconfiguration of aircraft lateral direction under aileron control surface failure as described in claim 4, characterized in that, Setting the control variable system matrix and Then the control law u for: （4）。 6. The method for fault-tolerant control and reconfiguration of aircraft lateral direction under aileron control surface failure as described in claim 1, characterized in that, In step 5, the adaptive law of the designed controller is: （9） in, , , ,and All are symmetric positive definite matrices; , , and As the initial value, , , and The current value; In a closed-loop system, the model error between the reference model and the system model is: The control law of the fault-tolerant controller is: （10） Substituting the closed-loop system expression (5) and the system model expression (6) into the model error expression (10), we obtain equation (11): （11） , and The value of makes , and All are true, and thus obtained and gain , making Stablize.

7. The method for lateral fault-tolerant control and reconfiguration of an aircraft under aileron control surface failure according to any one of claims 1-6, characterized in that, It also includes step 6: Under normal conditions, the flight control system is controlled by the reference controller. When an actuator failure occurs, the unknown input observer provides a fault estimate to the augmented closed-loop system.

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