A layer-by-layer fault tolerant control method for actuation / flight control systems

Abstract

The application provides a kind of actuation / flight control system layer-by-layer fault-tolerant control method, comprising the following steps: the total system and each subsystem of aircraft are hierarchically divided according to different levels such as actuation and flight control, and a composite space from the lowest layer subspace to the highest layer space is constructed; selecting fault characteristic quantity in the lowest layer space, calculating health status index using operator norm, and continuously taking subspace performance index as new space base, calculating higher layer health status index, until the highest layer system health status index is obtained; according to the highest layer system health status index of the total system and each subsystem of aircraft obtained, the total system and each subsystem of aircraft are controlled according to layer-by-layer fault-tolerant control law. The application realizes the adjustment and optimization of system control strategy by obtaining the quantitative representation of the current system health degree of aircraft, and obtains more stable flight quality.

Description

Technical Field

[0001] This invention belongs to the field of aircraft control technology, specifically relating to a layer-by-layer fault-tolerant control method for an actuation / flight control system. Background Technology

[0002] To further improve the reliability of aircraft, the aerospace industry is placing increasingly higher demands on the fault-tolerant capabilities of control systems, especially in the field of large civil aircraft and unmanned aerial vehicles (UAVs) with high reliability and ultra-long flight time. In order to ensure the success rate of flight missions under harsh operating conditions, higher requirements are placed on the performance and decision-making efficiency of fault-tolerant control systems.

[0003] Current large civil aircraft, such as the Airbus and Boeing series, are typically equipped with ample redundancy resources to ensure flight safety. Redundant unmanned aerial vehicles (UAVs) and other new types of aircraft in the aerospace field represent the future development direction. However, the control systems currently used to support these systems lack robust fault-tolerant control capabilities; single-point and discrete fault-tolerant designs lack systematicity and completeness.

[0004] Due to the advantages of distributed electro-hydrostatic actuators (EHAs), such as low heat generation, high energy efficiency, small size, light weight, and insensitivity to oil contamination, embedded electromechanical actuator (EMA) technology has also been greatly developed. Simultaneously, based on the requirements of aircraft power-to-weight ratio and reliability, a novel dissimilar redundancy actuation system is formed by combining the advantages of distributed hydraulic power actuation and electromechanical actuation, with EHA and EMA as basic redundancies. This system can serve as a new principle scheme for aircraft actuation systems, prioritizing the use of EHA as the main working channel. If the performance of this channel degrades or completely fails, it switches to the EMA-active EHA follow-up mode to continue actuation. This configuration is a novel power-to-electric propulsion structure with both electro-hydrostatic and electromechanical actuators. By avoiding common-cause / common-mode failures, it improves system reliability while simultaneously enhancing power-to-weight ratio and efficiency, bringing positive impacts to aircraft structural design, flight control, energy efficiency, and maintenance management. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a layer-by-layer fault-tolerant control method for actuation / flight control systems. The solution of this invention can solve the problems existing in the prior art.

[0006] The technical solution of this invention:

[0007] According to the first aspect, a layer-by-layer fault-tolerant control method for an actuation / flight control system is provided, comprising the following steps:

[0008] The overall system and its various subsystems of the aircraft are hierarchically divided according to different levels such as actuation and flight control, constructing a composite space from the lowest subspace to the highest space.

[0009] Fault characteristic quantities are selected in the lowest space, and the health status index is calculated using the operator norm. Then, the subspace performance index is continuously used as the new space basis to calculate the higher-level health status index until the highest-level system health status index is obtained.

[0010] Based on the highest-level system health status index of the overall system and each subsystem of the aircraft, the overall system and each subsystem of the aircraft are controlled according to the layer-by-layer fault-tolerant control law.

[0011] Furthermore, the division from the lowest subspace to the highest space is divided into reasonable levels according to the systems and subsystems that determine the flight control function of the aircraft.

[0012] Furthermore, the method for hierarchically dividing the overall system and various subsystems of the aircraft is as follows:

[0013] Determine the physical architecture design of the actuation and flight control systems;

[0014] Construct a composite spatial abstract model;

[0015] Determine whether the constructed composite spatial abstract model matches the system physical architecture. If it matches, continue to divide the subspace. If it does not match, return to modify the composite spatial abstract model.

[0016] The subspace module is divided according to the system and subsystem of the control function, down to the lowest subspace of the system.

[0017] Preferably, the flight control system of the aircraft includes control system subspaces for three axes: roll, pitch, and yaw. Each control system includes multiple control surface subspaces, each control surface includes multiple rudder loop system subspaces, and each rudder loop system includes an EHA subspace, an EMA subspace, and a control surface subspace. Each EHA subspace, EMA subspace, and control surface subspace serves as a lower-level subspace of the rudder loop system. The subspaces can be divided into the lowest-level subspaces of the corresponding modules according to the specific constituent modules.

[0018] Furthermore, the expression for the lowest level subspace is: S1 = span(ε1,…,ε n ), where ε1,…,ε n These are the n fault characteristics that constitute the lowest level subspace.

[0019] Furthermore, the calculation method for the health status index of the lowest-level subspace is as follows:

[0020] Determine the corresponding fault feature vector X1 = (x1, ..., x) for each fault feature quantity in the lowest subspace. n );

[0021] Calculate the comprehensive fault across all axes in the lowest-level subspace.

[0022] Determine the overall fault limit of the lowest subspace. Where X max =(x max-1 ,…,x max-n () represents the fault critical threshold vector corresponding to each fault feature quantity;

[0023] The health status index of the bottom-level subspace is determined based on the overall failure limit of the bottom-level subspace and the overall failure across all axes in the bottom-level subspace.

[0024] Furthermore, the calculation method for the highest-level system health status index is as follows:

[0025] Based on the health status index of each bottom-level subspace in the second-level subspace, the basis of the second-level subspace is defined, and its corresponding basis coordinates are X. 2 =(l health-1 ,…,l health-L ), where l health-1 ,…,l health-L Let L be the health status indices corresponding to the L lowest-level subspaces;

[0026] The health status index of the second subspace is calculated using Euclidean distance;

[0027] Repeat the above steps, calculating the health status index of the third subspace based on the health status index of the second subspace included in the third subspace, until the health status index of the highest subspace is obtained.

[0028] Furthermore, based on the obtained health status indices of the overall system and each subsystem of the aircraft, the method for controlling the overall system and each subsystem of the aircraft using layer-by-layer fault-tolerant control laws is as follows:

[0029] Determine the health status index of the highest level space corresponding to roll, pitch, and yaw respectively. If the corresponding health status index is equal to 1, continue to use the control strategy under normal operating conditions.

[0030] If the health status index of the highest-level space declines, the following layer-by-layer fault-tolerant control strategy will be adopted:

[0031] When the health status index of the rudder loop subspace corresponding to a certain axis function drops to the range of [0.8, 1), a passive fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop subspace. If the health status index of that rudder loop subspace continues to drop from 0.8, an active fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop. In the extreme case where the health status index drops to 0, the rudder loop performs a channel switch of the non-similar redundancy actuation system, with EMA replacing EHA to continue actuating. Other rudder loops adopt the same fault-tolerant processing strategy. Furthermore, if multiple rudder loops experience a drop in health status index, the process is escalated to the flight control level, where the comprehensive control gain is adjusted to achieve final fault tolerance.

[0032] According to the second aspect, an actuation / flight control system is provided, wherein the actuation / flight control system is controlled using an actuation / flight control method described above.

[0033] According to a third aspect, an aircraft is provided, wherein the aircraft is equipped with the aforementioned actuation / flight control system.

[0034] The beneficial effects of this invention compared to the prior art are as follows:

[0035] (1) This invention uses a mathematical modeling method for composite space to hierarchically divide a complex aircraft system, transforms the analysis of the structural characteristics and fault tolerance of physical objects into the analysis of abstract space, selects the key fault characteristics of the lowest subsystem to construct a spatial basis, and calculates the normalized health status index in the form of operator norm to obtain a quantitative representation of the current system health status, thereby further realizing the adjustment and optimization of the system control strategy and obtaining more stable flight quality.

[0036] (2) The effective quantitative characterization of the composite space health status index of the present invention can be used to guide the adaptive decision-making of fault-tolerant control strategies, and integrate all fault-tolerant control strategies into a layer-by-layer fault-tolerant control system from the bottom to the top, so that all the redundancy resources of the system can be fully developed and utilized. Attached Figure Description

[0037] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0038] Figure 1This diagram illustrates a conceptual design of an actuation system based on EHA and EMA as a basic redundancy architecture, according to an embodiment of the present invention. The diagram shows the command signal u calculated by the flight control computer. e1 and u e2 After being amplified by two drive control circuits 1 and 2 respectively, the corresponding motors of EHA and EMA are driven. The EHA motor drives the pump to generate high and low pressure chambers in the actuating cylinder through oil suction / discharge, and uses the pressure difference to push the piston rod to produce a linear stroke displacement x. e1 The EMA motor, through a reducer, applies rotational torque to the lead screw drive mechanism to generate linear displacement x. e2 The linear travel is finally converted into the deflection angle θ of the aircraft control surfaces through the linkage mechanism. d ;

[0039] Figure 2 A flowchart illustrating the design of a fault-tolerant control system based on the concept of composite space, according to an embodiment of the present invention, is shown.

[0040] Figure 3 This illustrates the principle of two-level composite space partitioning and mapping provided by an embodiment of the present invention;

[0041] Figure 4 An EHA fault feature subspace provided according to an embodiment of the present invention is shown;

[0042] Figure 5 The spatial structure of a heterogeneous actuation system with EHA and EMA as basic redundancies, according to an embodiment of the present invention, is shown, wherein: This represents the system-level composite space, which consists of the subsystem-level electrostatic-hydraulic subsystem space. Heji Electronic System Space In straight and form Composed of multiple components; and These represent the drive control subspace and the actuation module subspace of the electrostatic fluid subsystem, respectively. and These represent the drive control subspace and the actuation module subspace of the electromechanical system, respectively. These are the motor subspace, pump space, and actuator cylinder space of the electro-hydraulic actuation module, respectively. These are the motor subspace, reduction mechanism subspace, and output shaft space of the electromechanical actuation module, respectively; in the above expression, each higher-level space is derived from the lower-level subspace by a direct sum. It is composed of multiple methods;

[0043] Figure 6 The composite spatial hierarchy structure of the rudder loop of the actuation flight control system provided in the embodiment of the present invention is shown;

[0044] Figure 7 The flowchart of the fault-tolerant control strategy allocation algorithm based on the composite spatial health status index provided in the embodiment of the present invention is shown.

[0045] Figure 8 A graph showing the relationship between the EHA health status index and the leakage coefficient according to an embodiment of the present invention is shown.

[0046] Figure 9 A schematic diagram illustrating the steps of a layer-by-layer fault-tolerant control method for an actuation / flight control system according to an embodiment of the present invention is shown. Detailed Implementation

[0047] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0050] like Figure 9As shown, according to an embodiment of the present invention, a layer-by-layer fault-tolerant control method for an actuation / flight control system is provided, comprising the following steps:

[0051] The overall system and its various subsystems of the aircraft are hierarchically divided according to different levels such as actuation and flight control, constructing a composite space from the lowest subspace to the highest space.

[0052] Fault characteristic quantities are selected in the lowest space, and the health status index is calculated using the operator norm. Then, the subspace performance index is continuously used as the new space basis to calculate the higher-level health status index until the highest-level system health status index is obtained.

[0053] Based on the highest-level system health status index of the overall system and each subsystem of the aircraft, the overall system and each subsystem of the aircraft are controlled according to the layer-by-layer fault-tolerant control law.

[0054] This method uses mathematical modeling of composite space to hierarchically divide complex aircraft systems, transforming the analysis of the structural characteristics and fault tolerance of physical objects into the analysis of abstract space. Key fault characteristics of the lowest-level subsystems are selected to construct a spatial basis, and a normalized health status index is calculated in the form of operator norms. This yields a quantitative representation of the current system health level, enabling adjustments and optimizations to the system's control strategies to achieve more stable flight quality.

[0055] In one further embodiment, the division from the lowest subspace to the highest subspace is divided into reasonable levels according to the systems and subsystems that determine the flight control functions of the aircraft.

[0056] In another embodiment, the method for hierarchically dividing the overall system and various subsystems of the aircraft is as follows:

[0057] Determine the physical architecture design of the servo actuation and flight control system;

[0058] Construct a composite spatial abstract model;

[0059] Determine whether the constructed composite spatial abstract model matches the system physical architecture. If it matches, continue to divide the subspace. If it does not match, return to modify the composite spatial abstract model.

[0060] The subspace module is divided according to the system and subsystem of the control function, down to the lowest subspace of the system.

[0061] This method is used to hierarchically divide the overall system and various subsystems of the aircraft, laying the foundation for solving its health status index.

[0062] In a preferred embodiment, the flight control system of the aircraft includes control system subspaces for three axes: roll, pitch, and yaw. Each axis corresponds to a functional space including multiple control surface subspaces. Each control surface includes multiple rudder loop system subspaces. Each rudder loop system includes an EHA subspace, an EMA subspace, and a control surface subspace. Each EHA subspace, EMA subspace, and control surface subspace serves as a lower-level subspace of the rudder loop system. The subspaces can be divided down to the lowest-level subspace of the corresponding module according to the specific constituent modules.

[0063] In a further embodiment, the expression for the lowest level subspace is: S1 = span(ε1,…,ε n ), where ε1,…,ε n Let n be the fault feature quantities that constitute the lowest-level subspace. This space can be physically applied in the following ways: 1. The magnitude of the multidimensional vector space can characterize the health status of the entire system; 2. The projection length of the magnitude on each feature axis can be used for fault diagnosis, by which the system is determined to have a fault with the relevant feature if the projection length exceeds the corresponding threshold length; 3. Additional fault features can be described by adding extra dimensions.

[0064] In a further embodiment, the health status index of the lowest-level subspace is calculated as follows:

[0065] Determine the corresponding fault feature vector X1 = (x1, ..., x) for each fault feature quantity in the lowest subspace. n );

[0066] Calculate the comprehensive fault across all axes in the lowest-level subspace.

[0067] Determine the overall fault limit of the lowest subspace. Where X max =(x max-1 ,…,x max-n () represents the fault critical threshold vector corresponding to each fault feature quantity;

[0068] The health status index of the bottom-level subspace is determined based on the overall failure limit of the bottom-level subspace and the overall failure across all axes in the bottom-level subspace.

[0069] In a further embodiment, the calculation method for the highest-level system health status index is as follows:

[0070] Based on the health status index of each bottom-level subspace in the second-level subspace, the basis of the second-level subspace is defined, and its corresponding basis coordinates are X. 2 =(l health-1 ,…,l health-L), where l health-1 ,…,l health-L Let L be the health status indices corresponding to the L lowest-level subspaces;

[0071] The health status index of the second subspace is calculated using Euclidean distance;

[0072] Repeat the above steps, calculating the health status index of the third subspace based on the health status index of the second subspace included in the third subspace, until the health status index of the highest-level subspace is obtained.

[0073] In a further embodiment, the method for controlling the overall system and each subsystem of the aircraft based on the highest-level system health status index of the overall system and each subsystem is as follows:

[0074] Determine the health status index of the highest level space corresponding to roll, pitch, and yaw respectively. If the corresponding health status index is equal to 1, continue to use the control strategy under normal operating conditions.

[0075] If the health status index of the highest-level space declines, the following layer-by-layer fault-tolerant control strategy will be adopted:

[0076] When the health status index of the rudder loop subspace corresponding to a certain axis function drops to the range of [0.8, 1), a passive fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop subspace. If the health status index of that rudder loop subspace continues to drop from 0.8, an active fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop. In the extreme case where the health status index drops to 0, the rudder loop performs a channel switch of the non-similar redundancy actuation system, with EMA replacing EHA to continue actuating. Other rudder loops adopt the same fault-tolerant processing strategy. Furthermore, if multiple rudder loops experience a drop in health status index, the process is escalated to the flight control level, where the comprehensive control gain is adjusted to achieve final fault tolerance.

[0077] This method utilizes the effective quantitative characterization of the composite spatial health status index to guide adaptive decision-making for fault-tolerant control strategies. Integrating all fault-tolerant control strategies into a layer-by-layer fault-tolerant control system from the bottom to the top enables the comprehensive development and utilization of all system redundancy resources.

[0078] According to a second aspect embodiment, an actuation / flight control system is provided, wherein the actuation / flight control system is controlled using an actuation / flight control method described in this invention.

[0079] According to a third aspect embodiment, an aircraft is provided, the aircraft being equipped with the actuation / flight control system described in this invention.

[0080] To gain a better understanding of the layer-by-layer fault-tolerant control method for an actuation / flight control system provided by this invention, a detailed description is provided below with reference to specific examples and accompanying drawings.

[0081] A layer-by-layer fault-tolerant control method for an actuation / flight control system includes the following steps:

[0082] Step 1: Divide the overall system and various subsystems of the aircraft into different levels according to different levels such as actuation and flight control, and construct a composite space from the lowest subspace to the highest space.

[0083] Taking a certain type of aircraft with multiple control loops as an example, the specific ideas and implementation steps of this invention will be explained. This type of aircraft adopts a split control surface design (including left and right ailerons, left and right elevators, and vertical control surfaces), which has abundant controllable control surface resources and can have multiple redundancy combinations, thus possessing strong fault tolerance potential. The redundancy architecture and composition of the actuation system level of this type of aircraft are as follows: Figure 1 As shown.

[0084] Let S = span(ε1,…,ε) n Let be the mathematical expression for the space, where ε1,…,ε n Let n be the n linearly independent bases spanning this space. From the mathematical expression of the spanned space above, we can see two key properties of the space: structure and dimension. Structure characterizes the bases spanning the space and the relationships between them; dimension characterizes the number of bases spanning the space.

[0085] Space can be used as an abstract representation of concrete objects with corresponding dimensional characteristics, and space can be "mapped," with the resulting quantized values ​​used to characterize certain properties of that space. Therefore, "space" is a suitable mathematical tool for analyzing the fault tolerance capabilities of aircraft.

[0086] Since the fault tolerance of an aircraft mainly depends on its "actuation / flight control" system, and such systems have the characteristics of "layered composite", that is, the entire system contains multiple subsystems, and the system contains multiple molecular systems, the "composite space" of the present invention has strong applicability.

[0087] Composite space: A multidimensional space characterized by a hierarchical composite structure, where the basis coordinates of the spanned space are determined by mapping and quantization of the lower-level subspaces. The composite space concept has two core technologies in fault-tolerant control research: spatial partitioning and mapping quantization. Spatial partitioning: Dividing the space into reasonable levels according to the systems and subsystems that determine the flight control function of the aircraft; Mapping quantization: Selecting operator norms to quantize the spatial mapping, characterizing the performance of the subsystem corresponding to that subspace.

[0088] Assume there are n bases ε1,…,ε n Zhang Cheng's underlying subspace S1 = span(ε1,…,ε n The corresponding coordinate vector in space is defined as X1=(x1,…,x n If we use Euclidean distance to evaluate the mapping ability of this space on all bases, then we can use... Characterizes the comprehensive mapping capability of this space across all axes, and defines the upper limit of the mapping capability l of this space. max-1 At the same time, define the upper limit coordinate X corresponding to each basis. max =(x max-1 ,…,x max-n Then the formula can be used. This represents the upper limit of the mapping capability on this space. The above method of choosing the Euclidean distance satisfies the norm axiom, and the mapping operation that obtains a specific quantized value from n basis points is regarded as a mathematical operator T(S1). The current mapping capability of this space is evaluated using the normalization evaluation method. This mapping capability is quantized to the interval (0,1), and its value can be defined as follows:

[0089]

[0090] Assuming the basis of this lowest-level space represents the growth of fault characteristic quantities of a specific physical system, then X1 represents the current fault characteristic vector, X max-1 This represents the system's critical threshold vector for failure; the system's current health status can be represented as l. health-1 =l max-1 -l1, then (l health-1 +l1) / l max-1 =1, defining the comprehensive mapping capability of the remaining axis length as an indicator of the system's health status, then the health status of the lowest-level space S1 can be quantified as

[0091]

[0092] It can be seen that "the current fault level of the system + the current health status of the system = 1". Define T. health (S1)=l health-1If the final mapping operator represents the current health state of the system, then this operator can map the states of all lower-level subspaces to a higher-level space, obtaining the quantified values ​​of the current health state in the higher-level space. Similarly, the lowest-level space has other spaces S2, ..., S1 at the same level as space S1. L The corresponding operator T health Mapping yields T health (S i )=l health-i Let i = 1, 2, ..., L, and select the basis for the second-level subspace as... The corresponding basis coordinates are X 2 =(l health-1 ,…,l health-n ), where X 2 The superscript 2 indicates that the coordinate is in the second-level space. Therefore, the second-level subspace, composed of the lowest-level first-level subspace, can be defined as follows: Since the lowest level space processes fault characteristic quantities, through operator T health The mapped high-level space represents the health status, so the operator norm can be directly selected from the Euclidean distance starting from the second layer. Figure 3 The diagram illustrates the principle of the second-level composite space in the above process. The lowest-level subspace of the entire composite space selects dimensions corresponding to the fault characteristic quantities of the corresponding subsystems, and the composite space is gradually constructed based on this. To intuitively explain the above spatial division and the principle of mapping using Euclidean distance, as shown... Figure 4 As shown, taking the subspace corresponding to EHA as an example, three fault characteristic quantities—leakage, flow gain change, and damping ratio change—are selected to construct the bottom-level subspace. The base values ​​ε1, ε2, and ε3 represent the fault severity of leakage, damping ratio change, and flow gain change, respectively. x is selected as the threshold value. max-1 x max-2 and x max-3 Let x1, x2, and x3 be the corresponding critical thresholds, and x3 be the current fault values. Using the Euclidean distance operator mapping principle described above, the comprehensive health feature of the EHA can be obtained as l. max-l The health status of the EHA obtained by mapping is used as the comprehensive performance characteristic of the EHA. It is further combined with the comprehensive performance characteristics of the EMA and the control surface to obtain the health status of the entire control loop system. Figure 4 The bottom-level subspace shown is a multi-dimensional vector space, which can be physically applied in the following aspects: 1. The magnitude of the multi-dimensional vector space can characterize the health status of the entire system; 2. The projection length of the magnitude on each characteristic axis can be used for fault diagnosis. The method is that if the projection length exceeds the corresponding threshold length, the system can be determined to have the fault with the relevant feature; 3. Additional fault features can be described by adding additional dimensions.

[0093] Because the logical relationship from the actuation system level to the flight control level has a layered and complex structure; 1. the actuation system in this invention has a non-similarity redundancy configuration; 2. the fault types are diverse and the fault levels are different. Therefore, the proposed composite space modeling and analysis method is beneficial for establishing a hierarchical fault-tolerant control law allocation system. A single EHA or EMA is defined as the bottom-level subspace, the entire heterogeneous actuation system composed of EHA and EMA is defined as the second-level subspace, and all heterogeneous actuation systems, combined with corresponding redundancy control surfaces, form a higher-level flight control level composite space.

[0094] The overall controllability of an aircraft depends on its three-axis capabilities of roll, pitch, and yaw. Each of these functions is accomplished by multiple lower-level control surfaces, each controlled by a corresponding rudder loop system. The rudder loop system itself consists of a lower-level actuation system and control surfaces. Because the actuation system is heterogeneous, the entire rudder loop system can be viewed as a composite of the EHA subspace, EMA subspace, and control surface subspace. The health status of a single EHA subspace can be monitored through... Figure 4 The fault feature subspace shown is determined by mapping and quantization.

[0095] Based on the above analysis, to determine the fault tolerance capability of an aircraft, the analysis of the composite space must be conducted at least to the control loop system level. This allows higher-level three-axis control capabilities and overall aircraft control capabilities to be determined based on the health status of the control loop space. First, the control loop space S of the entire actuation / flight control system... flight (The subscript "flight" indicates that this space belongs to the flight control level) is divided into the actuation system subspace S. actuator (The subscript "actuator" indicates that this space belongs to the actuation system level) and the control surface subspace S surface (The subscript "surface" indicates that this space belongs to the control surface level.) Each controllable control surface is considered to be actuated by a heterogeneous actuator, and the entire actuation flight control system space can be regarded as the actuation system subspace S. actuator and rudder subspace S surface straight and The spanning basis vector for each subspace in this formula is chosen to be of the following form:

[0096] S actuator =span(DRAS1…DRAS) n );

[0097] S surface =span(SURF1…SURF) n (3)

[0098] In the above formula, DRAS i Represents a heterogeneous actuation system space, where each DRASi The corresponding controllable control surfaces can no longer be divided, but due to S actuator Each primitive in DRAS i Both are composed of EHA and EMA, therefore each DRAS can be further divided into i Divide into lower-level subspaces, namely:

[0099]

[0100] The EHA and EMA in each heterogeneous actuation system can be further divided as needed based on the specific component modules, such as... Figure 5 As shown. Based on the above division, the hierarchical structure of the actuation flight control system's rudder loop composite space can be as follows: Figure 6 As shown.

[0101] Since the flight control level of an aircraft is mainly divided into three axes of function: yaw, roll, and pitch, according to the concept of composite space, the systems and subsystems that determine the fault tolerance function of the entire aircraft are selected for division, resulting in: S yaw Yaw function space; S roll Scrolling functional space; S pitch For tilting and tilting functions; Upward rudder loop space; Downward rudder loop space; Left outer aileron rudder loop space; Left inner aileron rudder loop space; Right inner aileron rudder loop space; Right outer aileron rudder loop space; Left elevator circuit space; Right elevator rudder loop space; S surf Control surface space; S actu Actuation system space; S EHA EHA space; S EMA EMA space; bottom-level span(ε1,…,ε) m In the base ε, the selected fault characteristic quantity of the lowest-level spatial system is represented.

[0102] Step 2: Select fault characteristic quantities in the lowest space, calculate the health status index using operator norm, and continuously calculate higher-level health status indices using subspace performance indicators as new space bases until the highest-level system health status index is obtained.

[0103] Using the composite space method, all factors affecting the fault tolerance capability of an aircraft can be comprehensively considered, serving as the basis for allocating fault tolerance strategies. The influence of these factors is then normalized to the system's health status index. The health status index is a normalized dimensionless exponent H = f, determined by all subsystem factors related to the system's ability to achieve its intended functions. [0,1] (x1,…,x n ), where [0,1] indicates that the range of the function is from 0 to 1, and the variables x1,…,x n To determine the quantified values ​​of the current states of n subsystems for the current system health status index, the mapping function f is determined based on the selected operator norm. The specific fault-tolerance steps are from the lowest level EHA to the entire flight control level. Based on the percentage value of the health status index of a single control loop system, fault-tolerance control strategies for different faults are adopted sequentially: after modeling and analyzing the fault tolerance capability of the entire aircraft using a composite space, all control loops can be considered comprehensively, and the selection of fault-tolerance strategies is determined by the health status of the control loops. To determine the health status of the control loops, the concept of a control loop system health status index is further proposed to guide the selection of fault-tolerance strategies. The formula is expressed as follows:

[0104]

[0105] Current actuationefficiency and Max actuationefficiency These represent the current and maximum operating efficiencies of the rudder circuit, respectively. damagedcontrolsurface and S controlsurface The effective area and total effective area of ​​the wing surface after damage are respectively used. The specific value of the health status index is obtained through norm quantification. The significance of the rudder loop health status index is to measure the command tracking capability of the flight control system. The determination method involves mapping multiple fault characteristics to the dimensions of a subspace, and constructing the health status index using the mapping of the underlying subspace.

[0106] The entire aircraft has multiple control loops. Within the entire composite space, the underlying subspace is continuously mapped and quantized to higher-level spaces. Ultimately, the health status index of all control loops can be obtained, forming a health status index vector.

[0107]

[0108] in and These are the health status indices of the rudder circuits in the up and down directions, respectively. and These are the health status indices for the left outer aileron and inner aileron rudder loops, respectively. and These are the health status indices for the right inner aileron and outer aileron rudder loops, respectively. and These are the health status indices for the left and right elevator circuits, respectively.

[0109] The specific steps for calculating the health status index vector are as follows:

[0110] Step 1: Initialization of the composite space matrix. First, based on the specific structure of the fault-tolerant system and subsystems of the whole machine, the composite space is divided, and then the initialization matrix is ​​determined as shown in formula (7):

[0111]

[0112] The matrix is ​​divided into three layers. The bottom layer can be directly determined by the fault information of the most basic actuator. The middle layer matrix can be determined by the health status of the actuation system, and the top layer can be determined by the health status index of the entire rudder loop flight control system.

[0113] Step 2: Determine the health status index for each subspace. Define n fault characteristic quantities for the EHA subspace, namely S EHA =span(ε1,…,ε n The coordinates of the corresponding fault characteristic quantities are defined as X = (x1, ..., x). n The corresponding threshold coordinate is X. max =(x max-1 ,…,x max-n The current fault level is determined in 2-norm form.

[0114]

[0115] The current health status index of EHA can be obtained from the relationship between the fault level and the health status index.

[0116]

[0117] A similar health status index to the EMA can be determined as H. EMA ,because The health status index of the higher-level heterogeneous servo actuation system can then be determined as follows: The specific calculation formula is as follows

[0118]

[0119] Based on this ascending method, the initialization matrix can be reduced to the form shown in formula (11).

[0120]

[0121] Since the health status index of the control surface is positively correlated with the remaining effective area, the health status index of a single control surface can be determined as follows: Where S all For the total effective area, S left Given the remaining effective area, the health status index of the closed-loop actuation / flight control rudder loop system can ultimately be determined at the highest level as follows:

[0122]

[0123] The matrix can be further reduced in dimension to the form described in formula (13).

[0124]

[0125] Based on the above processing, for this type of aircraft with a heterogeneous actuation system, the most basic fault characteristic quantities and the functional relationship between the entire control loop system can be determined as follows:

[0126]

[0127] The independent variables of this function can be identified as the fault characteristic quantities of EHA and EMA, and the proportion of remaining effective control surfaces. The method for determining this health status index allows the function's value range to be defined as 0 to 1.

[0128] Step 3: Determination of the health status index vector of the flight control layer. Based on the operator norm defined in formula (14), and the matrix dimensionality reduction algorithm of the composite space of the overall fault tolerance capability, the health status index vector of the whole machine shown in formula (6) can be obtained.

[0129] Step 3: Based on the obtained health status index of the highest-level system of the aircraft's overall system and each subsystem, control is carried out using the layer-by-layer fault-tolerant control law of the aircraft's overall system and each subsystem.

[0130] The fault-tolerant control strategy allocation algorithm based on the composite spatial health status index is as follows: Figure 7 As shown. In order to maintain a high health status index vector through fault tolerance, fault tolerance based on the health status index is carried out in two aspects: First, passive fault tolerance control is performed at the servo actuation system level for each rudder loop to slow down the performance degradation of the rudder loop and maintain a high health status index; Second, when a serious performance degradation or failure of the rudder loop occurs, active fault tolerance is performed at the flight control level based on the health status index vector by adjusting the integrated control gain and reconstructing the remaining effective margin to achieve the intended function. To verify the correctness of the health status index normalization algorithm shown in formula (14), fault parameters are selected for simulation analysis, assuming that the EHA leakage coefficient variation range is C hl =0.1×10 -10 ~1.0×10 -10 [(m 3The leakage coefficient under normal operating conditions is 0.1 × 10⁻⁶ Pa / s, which is 0.1 × 10⁻⁶ Pa / s. -10 [(m 3 The maximum threshold for leakage faults is 1.0 × 10⁻⁶ Pa / s. -10 [(m 3 As the leakage increases, the current leakage coefficient changes from 0% to 100% as a percentage of the fault threshold. Assuming no other faults, the relationship between the leakage fault and other health status indices is as follows: Figure 8 As shown. By Figure 8 It can be seen that during the process of the leakage fault reaching the maximum threshold from normal, the health status index of the entire related rudder loop system dropped from 1 to about 0.89. It can be seen that the health status index quantification formula shown in formula (14) effectively quantifies all fault information to [0,1] and the characterization of the impact of point faults on the entire rudder loop system is also effective. According to Figure 7 The flowchart shown illustrates the hierarchical fault-tolerant control decision-making process. This rudder loop system requires passive fault tolerance at the servo actuation system level to optimize control gain and thus ensure improved performance of the rudder loop system.

[0131] In summary, the layer-by-layer fault-tolerant control method for actuation / flight control systems provided by this invention has at least the following advantages compared to existing technologies:

[0132] (1) This invention uses a mathematical modeling method of composite space to hierarchically divide the complex aircraft system, transforms the analysis of the structural characteristics and fault tolerance of the physical object into the analysis of the abstract space, selects the key fault characteristics of the lowest subsystem to construct the spatial basis, and calculates the normalized health status index in the form of operator norm to obtain a quantitative representation of the current system health status. This allows for the adjustment and optimization of the system control strategy, thereby obtaining more stable flight quality.

[0133] (2) The effective quantitative characterization of the composite space health status index of the present invention can be used to guide the adaptive decision-making of fault-tolerant control strategies, and integrate all fault-tolerant control strategies into a layer-by-layer fault-tolerant control system from the bottom to the top, so that all the redundancy resources of the system can be fully developed and utilized.

[0134] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A layer-by-layer fault-tolerant control method for an actuation / flight control system, characterized in that, Includes the following steps: The overall system and its subsystems of the aircraft are hierarchically divided according to different levels such as actuation and flight control, constructing a composite space from the lowest subspace to the highest level; the method for hierarchically dividing the overall system and its subsystems of the aircraft is as follows: Determine the physical architecture design of the actuation and flight control systems; Construct a composite spatial abstract model; Determine whether the constructed composite spatial abstract model matches the system physical architecture. If it matches, continue to divide the subspace. If it does not match, return to modify the composite spatial abstract model. The subspace module is divided according to the system and subsystems of control functions, down to the lowest subspace of the system; the expression for the lowest subspace is: ,in These are the n fault characteristics that constitute the lowest-level subspace; Fault characteristic quantities are selected in the lowest-level space, and the health status index is calculated using the operator norm. Then, using the subspace performance indicators as the new space basis, higher-level health status indices are continuously calculated until the highest-level system health status index is obtained. The calculation method for the health status index of the lowest-level subspace is as follows: Determine the corresponding fault feature vector for each fault feature quantity in the lowest subspace. ; Calculate the comprehensive fault across all axes in the lowest-level subspace. ; Determine the overall fault limit of the lowest subspace. ,in For each fault feature quantity, there is a corresponding fault critical threshold vector. The health status index of the bottom-level subspace is determined based on the overall failure limit of the bottom-level subspace and the overall failure across all axes in the bottom-level subspace. ; The calculation method for the health status index of the highest-level system is as follows: Based on the health status index of each bottom-level subspace in the second-level subspace, which serves as the basis of the second-level subspace, the corresponding basis coordinates are: ,in Let L be the health status indices corresponding to the L lowest-level subspaces; The health status index of the second subspace is calculated using Euclidean distance; Repeat the above steps, and calculate the health status index of the third subspace based on the health status index of the second subspace included in the third subspace, until the health status index of the highest subspace is obtained. Based on the highest-level system health status index of the overall system and each subsystem of the aircraft, the overall system and each subsystem of the aircraft are controlled according to the layer-by-layer fault-tolerant control law; Based on the health status indices of the overall system and each subsystem of the aircraft, the method for controlling the overall system and each subsystem of the aircraft using the layer-by-layer fault-tolerant control law is as follows: Determine the health status index of the highest level space corresponding to roll, pitch, and yaw respectively. If the corresponding health status index is equal to 1, continue to use the control strategy under normal operating conditions. If the health status index of the highest-level space declines, the following layer-by-layer fault-tolerant control strategy will be adopted: When the health status index of the rudder loop subspace corresponding to a certain axis function drops to the range of [0.8, 1), a passive fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop subspace. If the health status index of that rudder loop subspace continues to drop from 0.8, an active fault-tolerant control strategy at the actuation system level is applied to the single rudder loop represented by that rudder loop subspace. In the extreme case where the health status index drops to 0, the rudder loop performs a channel switch of the non-similar redundancy actuation system, with EMA replacing EHA to continue actuating. Other rudder loops adopt the same fault-tolerant processing strategy. Furthermore, if multiple rudder loops experience a drop in health status index, the process is escalated to the flight control level, where the comprehensive control gain is adjusted to achieve final fault tolerance.

2. The layer-by-layer fault-tolerant control method for an actuation / flight control system according to claim 1, characterized in that, The division from the lowest to the highest subspace is based on the systems and subsystems that determine the flight control function of the aircraft, forming a reasonable hierarchy.

3. The layer-by-layer fault-tolerant control method for an actuation / flight control system according to claim 2, characterized in that, The flight control system of an aircraft includes control system subspaces for three axes: roll, pitch, and yaw. Each control system includes multiple control surface subspaces, each control surface includes multiple rudder loop system subspaces, and each rudder loop system includes an EHA subspace, an EMA subspace, and a rudder surface subspace. Each EHA subspace, EMA subspace, and rudder surface subspace serves as a lower-level subspace of the rudder loop system. These subspaces can be divided into the lowest-level subspace of the corresponding module according to the specific constituent modules.

4. An actuation / flight control system, characterized in that, The aforementioned actuation / flight control system is controlled using any one of the actuation / flight control methods of claims 1-3.

5. An aircraft, characterized in that, The aircraft is equipped with the actuation / flight control system as described in claim 4.

Images