A hierarchical method for quantifying aircraft health

Abstract

This invention relates to a hierarchical aircraft health quantification method, comprising the steps of obtaining a hierarchical fault-function logic of the aircraft based on aircraft design information; constructing an aircraft health quantification model based on the fault-function logic relationship; and performing health quantification calculations based on the constructed aircraft health quantification model and aircraft history data. The method of this invention can effectively capture the impact of aircraft-level functional and mission capabilities caused by LRU layer anomalies (BIT data) and operating time during aircraft system operation, and obtain a quantitative representation of aircraft health. This helps maintenance personnel and aircraft dispatchers to comprehensively understand the situation and apply this type of health measurement to effective maintenance plans and scheduling arrangements.

Description

Technical Field

[0001] This invention belongs to the field of avionics technology and is a health assessment method for complex aircraft systems. Background Technology

[0002] As part of system health management, health assessment provides crucial support for maintenance decision-making and the operational scheduling of aircraft resources. Due to the increasing complexity of aircraft functions, there is a need to develop fault-function impact models for multi-layered functional aircraft to conduct comprehensive aircraft health assessments and provide mission-oriented capability evaluations. However, similar assessment techniques have not yet been applied to aircraft health management in China. Summary of the Invention

[0003] The purpose of this invention is to provide a technology for comprehensive health assessment of complex aircraft systems, mainly used for comprehensive health measurement of aircraft systems. This technology can serve as a supporting technology for comprehensive aircraft health management.

[0004] The technical solution of this invention is:

[0005] A hierarchical method for quantifying aircraft health includes the following steps:

[0006] Step 1) Based on the aircraft design information, obtain the hierarchical fault-functional logic of the aircraft.

[0007] 1.1) The aircraft is divided into four levels: aircraft level, system level, subsystem level and LRU level. The complete functional division of the aircraft is reflected in different levels.

[0008] 1.2) Establish the mapping relationship between the functions of each layer and their direct components, describe the impact of health changes of each layer's components (especially faults / abnormal events detected by BIT) on mission / function-related capabilities, and realize top-down data collection and hierarchical health assessment to obtain the hierarchical fault-functional logic of the aircraft.

[0009] The division of functions for each level is obtained through FMECA and security analysis at each level.

[0010] "Direct components" refers to the next level of components at each level. At the aircraft level, the direct components are the various systems; at the system level, the direct components are the subsystems; and at the subsystem level, the direct components are the various units.

[0011] The specific manifestations of the fault-functional logic at each layer are as follows:

[0012] Aircraft level: The fault-function logic at this level is based on the relationship between the aircraft-level functional status and the health status of each system under the aircraft level. Specifically, the mapping relationship is expressed as the impact relationship between the functional failure of a system-level component and the functional failure of the aircraft level.

[0013] The aircraft-level systems include airframe structure, flight-critical systems, and mission systems.

[0014] The aircraft-level functions include in-flight environmental control, wing operation, in-flight refueling, aircraft control, and formation flying.

[0015] The information on aircraft-level functional status and the health status of each subordinate system at the aircraft level was obtained by collecting relevant aircraft design documents.

[0016] System level: The fault-function logic at this level is based on the relationship between the system-level functional status and the health status of each subsystem under the system level. The specific mapping relationship should be expressed as the impact relationship of subsystem-level component functional failure → system-level functional failure.

[0017] The task system's subsystems include ICP, network communication, integrated display and control, radio frequency, and optoelectronics.

[0018] The mission system's functions include radar detection, electro-optical detection, CNI (Computer-Aided Infrared) system, integrated anti-jamming, antenna / RF integration, onboard equipment communication, identification, route planning and coordination.

[0019] The system-level functional status and the corresponding health status information of each subsystem under the system level are obtained by collecting relevant aircraft design documents.

[0020] Subsystem level: The fault-function logic at this level is based on the relationship between the subsystem-level function and the health status of each LRU under the subsystem. The specific mapping relationship is expressed as the impact relationship between health abnormalities of LRU-level components and subsystem-level function failure.

[0021] Among them, the impact relationship of the integrated display and control (ICDS) subsystem functional failure reflects the impact of finished product failure on the subsystem function;

[0022] The information on the functions at each subsystem level and the health status of each LRU under each subsystem is obtained by collecting relevant aircraft design documents.

[0023] Step 2) Construct a quantitative model of aircraft health based on the fault-function logic relationship.

[0024] 2.1) Based on the loss of relevant functions of corresponding subsystem-level, system-level, and aircraft-level components caused by the failure of each LRU-level unit, construct an aircraft health quantification model;

[0025] 2.2) Based on the loss of functions of other components at this level and the resulting loss of related functions of the corresponding higher-level components, construct a quantitative model of aircraft health;

[0026] 2.3) Based on the requirements and the obtained design information, iteratively build a complete quantitative model of aircraft health by stepping through each level.

[0027] The aircraft health quantification model uses logic gates to represent the impact of the loss of functions of different components at different levels or within the same level on the loss of functions at the next higher level.

[0028] Step 3) Based on the constructed aircraft health quantification model and aircraft history data, perform health quantification calculations.

[0029] 3.1) Establish a general health assessment function

[0030] A general health assessment function is used to assess the health of each level of failure mode → functional failure. Based on the remaining functional availability (RFA) of the evaluated object and the assessment requirements of different levels, a specific general health assessment function is generated in combination with the hierarchical model.

[0031] First, based on graphical modeling and data parsing, all levels of RFA are transformed into processing and analysis of the relationship between failure mode and functional failure. Then, according to different objects, the correspondence between function and failure is refined, and the final general health assessment function is expressed as follows:

[0032]

[0033] The variables in the above formula are explained as follows:

[0034] H G —General health assessment values;

[0035] RFA i —The remaining functionality availability of the i-th function contained in the object;

[0036] w i —The weight of the i-th function;

[0037] N — The total number of functionalities contained in the object.

[0038] 3.2) Calculate Remaining Function Availability (RFA) based on four different scenarios. i

[0039] RFA i The determination should be limited by the specific logical relationship between the failure mode and the function, mainly including four cases: failure-function independence, series dependency, parallel dependency, and voting relationship.

[0040] 3.2.1) Functional Independence Case

[0041] If a functional failure in an aircraft health quantification model is attributed to only one failure mode, then in this case, it is assumed that the failure of function k is solely due to a single failure mode f. k Due to the occurrence of [something], the corresponding remaining functional availability in this case is:

[0042] RFA k =1-C k

[0043] In the above formula, C k Fault mode f k The higher the hazard level, the lower the remaining functional availability, and consequently, the lower the overall system health assessment value.

[0044] C k The specific value is obtained from the following two cases:

[0045] If the failure mode does not occur, the focus is primarily on ready LRUs / LRMs that have already undergone offline maintenance. The severity level (C) for different failure modes is determined based on FMECA or FMECA. k =λ k d k β k t LRU / LRM The corresponding remaining functionality availability is RFA. k =1-λ k d k β k t LRU / LRM ; where C k Fault mode f k The degree of harm, λ k The failure rate for this failure mode can be obtained in FMECA, d k d represents the frequency ratio of fault occurrences. k Use statistical values ​​from resume information and prior values ​​from FMECA; if these cannot be obtained, set the value to d. k =1, β k This is the impact degree of the failure mode, i.e., the ability of the failure to develop into functional failure, with a value range of 0 < β. k ≤1,t LRU / LRM This refers to the runtime of the LRU / LRM to which the fault mode belongs, measured in flight hours. It is obtained by reading flight history information during pre-flight assessment and by accumulating flight mission time during post-flight assessment. It can be seen that as t... LRU / LRM The increase and d k The improvement of C k The larger the RFA k The smaller.

[0046] If a BIT report indicates a fault, the corresponding fault mode can be identified by reading flight data or history information. k The BIT feature is in the active state, at which point C k Set to 1, corresponding RFA k is 0.

[0047] 3.2.2) Series Dependency Case

[0048] If an "OR" logic combination appears in the aircraft health quantification model, resulting in a series dependency, then in a series configuration, the failure of a certain function i is attributed to an OR logic combination of multiple failure modes. That is, the occurrence of any one of the failure modes k will lead to the failure of function i.

[0049] The corresponding remaining functionality availability is represented as follows:

[0050]

[0051] Among them, C k Fault mode f k The degree of harm, n i Let be the number of fault modes corresponding to function i, and ∏() represent a continuous product;

[0052] 3.2.3) Parallel Dependency Case

[0053] If an AND logic combination appears in the aircraft health quantification model, resulting in parallel dependency, the failure of a certain function j is attributed to the AND logic combination of multiple failure modes. That is, the failure of function j will only occur if all failure modes combined by the AND logic combination occur. The corresponding remaining functional availability is represented as follows:

[0054]

[0055] Among them, C k Fault mode f k The degree of harm, n j The number of fault modes corresponding to function j;

[0056] 3.2.4) Voting Relationship

[0057] If the system function is achieved by voting on the relevant outputs of its redundant components, a voting relationship occurs, and a reliability analysis model is used to evaluate the voting relationship.

[0058] 3.2.4.1) When no faults occur, the RFA representation of function v is as follows:

[0059]

[0060] Wherein, the set {i, j, ..., n}f There are n - k elements in total. m is the normal function serial number, n is the total number of all functions, i is the serial number of the first failed function, j is the serial number of the second failed function, and n f is the serial number of the f nth failed function. The distinctness means that any two of them are different from each other;

[0061] 3.2.4.2) When l faults occur, 0 < l < n - l, the remaining n - l components form a voting form of taking k out of n - l. The RFA of function v is expressed as

[0062]

[0063] where the set {i, j,..., n f} has n - l - k elements.

[0064] 3.2.4.3) When n - k faults occur, the remaining k components form a series - dependent relationship. The RFA of function v is expressed as

[0065]

[0066] 3.2.4.4) When at least n - k + 1 faults occur, the RFA of function v is 0.

[0067] 3.3) Aircraft mission capability evaluation

[0068] According to the top - down structure provided by the aircraft health quantification model, collect fault information or system operation resume information, obtain the aircraft - level function mission availability supported by each aircraft system / sub - system, conduct aircraft mission capability evaluation, and then complete the hierarchical aircraft health quantification process. The expression form of the function mission availability of mission M is:

[0069]

[0070] where N M represents the number of aircraft - level functions included in mission M, RFA i is the remaining availability of one aircraft - level function i, and w i is the weight of function i under this mission. If it cannot be obtained, it is set to 1.

[0071] The advantages of the present invention are:

[0072] The hierarchical aircraft health quantification method of this invention can effectively capture the impact of LRU layer anomalies (BIT data) and runtime on aircraft-level functions and mission capabilities during aircraft system operation, based on a hierarchical aircraft health quantification model, and obtain a quantitative representation of aircraft health. This helps maintenance personnel and aircraft dispatchers to comprehensively understand the situation and apply this type of health measurement to effective maintenance plans and scheduling arrangements. Attached Figure Description

[0073] Figure 1 A flowchart for a hierarchical method for quantifying aircraft health.

[0074] Figure 2 The aircraft system is divided into different layers.

[0075] Figure 3 This represents the mapping relationship between aircraft-level functions and systems.

[0076] Figure 4 The system-level (task system) components (subsystems) → function mapping table.

[0077] Figure 5 For subsystem-level finished products → function mapping.

[0078] Figure 6 A diagram of a hierarchical health quantification model for the task system layer.

[0079] Figure 7 The aircraft malfunction was caused by a failure of the mission system.

[0080] Figure 8 A diagram of the hierarchical health quantification model for the IDCS subsystem.

[0081] Figure 9 A diagram of the LRU layer hierarchical health quantification model for PIU.

[0082] Figure 10 This is a radar chart representation of multi-task availability. Detailed Implementation

[0083] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0084] By collecting aircraft design information, a hierarchical aircraft health quantification model is constructed. Based on this model and combined with aircraft history data (such as LRU service time, BIT failure information, etc.), health quantification calculations are performed to obtain overall and mission-oriented health metrics of the aircraft system, providing assessment and decision support for maintenance personnel and aircraft scheduling managers.

[0085] The hierarchical aircraft health quantification method of the present invention mainly includes: logical sorting of aircraft hierarchical fault-functional impact, hierarchical health quantification modeling, and health quantification calculation.

[0086] 1) Based on aircraft design information, obtain the hierarchical fault-functional logic of the aircraft.

[0087] The generation of this type of impact relationship is mainly achieved by sorting out the safety / reliability analysis documents, functional hazard analysis (FHA) documents, and FMEA documents, and organizing the fault-function impact relationships at each level of the aircraft in the form of tables or fault trees.

[0088] 2) Construction of a hierarchical health quantification model

[0089] Based on the fault-functional logical relationship, a health quantification model is constructed. The functional-composition model of each layer is built using a graphical modeling tool, generating a loadable file (such as XML) to obtain the static structural data required for health quantification calculation. The previously constructed graphical model, due to its intuitive specificity, can be improved and updated iteratively.

[0090] 3) Health Quantification Calculation

[0091] By loading relevant structured models and reading flight history information, the health quantification algorithm evaluates aircraft health (a non-negative scalar) and mission execution capability (a multi-dimensional vector represented by a radar chart).

[0092] Overall plan as follows Figure 1 As shown. The specific steps of the method are as follows:

[0093] Step 1) Based on the aircraft design information, obtain the hierarchical fault-functional logic of the aircraft.

[0094] 1.1) The aircraft is divided into four levels: aircraft level, system level, subsystem level and LRU level. The complete functional division of the aircraft is reflected in different levels.

[0095] 1.2) Establish the mapping relationship between the functions of each layer and their direct components, describe the impact of health changes of each layer's components (especially faults / abnormal events detected by BIT) on mission / function-related capabilities, and realize top-down data collection and hierarchical health assessment to obtain the hierarchical fault-functional logic of the aircraft.

[0096] The division of functions for each level is obtained through FMECA and security analysis at each level.

[0097] In this context, "direct components" refer to the next level of components at each level. At the aircraft level, the direct components are the various systems; at the system level, the direct components are the subsystems; and at the subsystem level, the direct components are the individual units. The hierarchical division of an aircraft can be seen... Figure 2 .

[0098] The specific manifestations of faults in the functional logic of each layer are as follows:

[0099] Aircraft level: The fault-function logic at this level is based on the relationship between the aircraft-level functional status and the health status of each system under the aircraft level. Specifically, the mapping relationship is expressed as the impact relationship between the functional failure of a system-level component and the functional failure of the aircraft level.

[0100] The aircraft-level systems include airframe structure, flight-critical systems, and mission systems.

[0101] The aircraft-level functions include in-flight environmental control, wing operation, in-flight refueling, aircraft control, and formation flying.

[0102] The information on aircraft-level functional status and the health status of each subordinate system at the aircraft level was obtained by collecting relevant aircraft design documents; the specific mapping can be found here. Figure 3 As shown, "AC-XX" is the aircraft-level function designation.

[0103] System level: The fault-function logic at this level is based on the relationship between the system-level functional status and the health status of each subsystem under the system level. The specific mapping relationship should be expressed as the impact relationship of subsystem-level component functional failure → system-level functional failure.

[0104] The task system's subsystems include ICP, network communication, integrated display and control, radio frequency, and optoelectronics.

[0105] The mission system's functions include radar detection, electro-optical detection, CNI (Computer-Aided Infrared) system, integrated anti-jamming, antenna / RF integration, onboard equipment communication, identification, route planning and coordination.

[0106] The system-level functional status and the corresponding health status information of each subsystem under the system level are obtained by collecting relevant aircraft design documents, such as... Figure 4 As shown, "MS-XX" is the task system function number.

[0107] Subsystem level: The fault-function logic at this level is based on the relationship between the subsystem-level function and the health status of each LRU under the subsystem. The specific mapping relationship is expressed as the impact relationship between health abnormalities of LRU-level components and subsystem-level function failure.

[0108] Among them, the impact relationship of the integrated display and control (ICDS) subsystem functional failure reflects the impact of finished product failure on the subsystem function;

[0109] The information on the functions at the subsystem level and the health status of each LRU under the subsystem is obtained by collecting relevant aircraft design documents, such as... Figure 5As shown in the figure, "ICDS-XX" is the function number of the integrated display and control system.

[0110] Step 2) Construct a quantitative model of aircraft health based on the fault-function logic relationship.

[0111] 2.1) Based on the loss of relevant functions of corresponding subsystem-level, system-level, and aircraft-level components caused by the failure of each LRU-level unit, construct an aircraft health quantification model;

[0112] 2.2) Based on the loss of functions of other components at this level and the resulting loss of related functions of the corresponding higher-level components, construct a quantitative model of aircraft health;

[0113] 2.3) Based on the requirements and the obtained design information, iteratively build a complete quantitative model of aircraft health by stepping through each level.

[0114] Taking the Integrated Display and Control Subsystem (ICDS) as an example, the health quantification model should primarily reflect the loss of ICDS-related functions, mission system-related functions, and aircraft-related functions due to the failure of the underlying Processing Interface Unit (PIU). It should also reflect the logical combination relationship between the loss of functions in other subsystems (Suspension Management Subsystem, SMS) and the loss of ICDS functions on aircraft-related functions. The model's completeness should be iteratively improved based on requirements and acquired design information.

[0115] At the highest level, the aircraft level, the model contains multiple system models. The mission system is one of them. Details of the mission system layer model are as follows... Figure 6 As shown.

[0116] This layer reveals two subsystems within the mission system: the Integrated Display and Control Subsystem (ICDS) and the Suspension Management Subsystem (SMS). The 10 ports in the ICDS model represent 10 ICDS subsystem-level functions (ICDS_D01-ICDS_D10). Logical combinations within these functions (primarily OR logic) can lead to the loss of mission system functions (MS_D01-MS_D05). Furthermore, within the SMS subsystem, the failure of SMS_D03 will also cause the failure of MS_D03 (passive interference). Therefore, this, combined with the failure of other ICDS functions (ICDS_D04-ICDS_D05) that also cause failure, forms an OR logic (or possibly an AND logic), resulting in the failure of MS_D03. The failure of MS_D03 affects the aircraft, causing the corresponding higher-level function AC_D65 to fail. For example... Figure 7 As shown.

[0117] Clicking the IDCS model control at the task system layer will take you to the subsystem layer where IDCS resides, such as... Figure 8As shown.

[0118] This layer mainly consists of three parts: First, the PIU (Product LRU) model. The functional failure of the PIU is reflected as a port at the output end of the PIU model control. Since it cannot be further divided, the input end is the failure mode of the LRU. According to FMECA, the failure mode of the LRU will cause the LRU itself to malfunction or fail (local / partial impact); Second, the IDCS functional failure (ICDS_D01-ICDS_D10). The functional failure of the PIU will cause the failure of this type of subsystem; Third, the logic gates. Different PIU functional failures will cause the IDCS functional failure through logic combination (mainly "OR" logic here).

[0119] Clicking on the PIU model at the subsystem level will take you to the LRU level (the lowest level) where the PIU resides, such as... Figure 9 As shown. This layer should no longer contain model controls, but only basic modeling elements (Atoms) faults (LRU inherent fault modes), alarms (the local impact of faults at the LRU level, usually the failure of the LRU's own function), and connections to represent the influence relationship between the former two.

[0120] Step 3) Based on the constructed aircraft health quantification model and aircraft history data, perform health quantification calculations.

[0121] 3.1) Establish a general health assessment function

[0122] A general health assessment function is used to assess the health of each level of failure mode → functional failure. Based on the remaining functional availability (RFA) of the evaluated object and the assessment requirements of different levels, a specific general health assessment function is generated in combination with the hierarchical model.

[0123] First, based on graphical modeling and data parsing, all levels of RFA are transformed into processing and analysis of the relationship between failure mode and functional failure. Then, according to different objects, the correspondence between function and failure is refined, and the final general health assessment function is expressed as follows:

[0124]

[0125] The variables in the above formula are explained as follows:

[0126] H G —General health assessment values;

[0127] RFA i —The remaining functionality availability of the i-th function contained in the object;

[0128] w i —The weight of the i-th function;

[0129] N — The total number of functionalities contained in the object.

[0130] 3.2) Calculate Remaining Function Availability (RFA) based on four different scenarios. i

[0131] RFA i The determination of the failure mode should be limited by the specific logical relationship between the failure mode and the function, which mainly includes four cases: failure-function independence relationship, series dependency, parallel dependency and voting relationship.

[0132] 3.2.1) Functional Independence Case

[0133] If functional failure in the aircraft health quantification model is attributed to only one failure mode, such as Figure 9 In the PIU (Portable Utility Unit), the failure mode → LRU (Least Recently Used) level function failure relationship is described. In this case, it is assumed that function k fails solely due to a single failure mode f. k Due to the occurrence of [something], the corresponding remaining functional availability in this case is:

[0134] RFA k =1-C k

[0135] In the above formula, C k Fault mode f k The higher the hazard level, the lower the remaining functional availability, and consequently, the lower the overall system health assessment value.

[0136] C k The specific value is obtained from the following two cases:

[0137] If the failure mode does not occur, the focus is primarily on ready LRUs / LRMs that have already undergone offline maintenance. The severity level (C) for different failure modes is determined based on FMECA or FMECA. k =λ k d k β k t LRU / LRM The corresponding remaining functionality availability is RFA. k =1-λ k d k β k t LRU / LRM ; where C k Fault mode f k The degree of harm, λ k The failure rate for this failure mode can be obtained in FMECA, d k d represents the frequency ratio of fault occurrences. k Use statistical values ​​from resume information and prior values ​​from FMECA; if these cannot be obtained, set the value to d. k =1, β kThis is the impact degree of the failure mode, i.e., the ability of the failure to develop into functional failure, with a value range of 0 < β. k ≤1,t LRU / LRM This refers to the runtime of the LRU / LRM to which the fault mode belongs, measured in flight hours. It is obtained by reading flight history information during pre-flight assessment and by accumulating flight mission time during post-flight assessment. It can be seen that as t... LRU / LRM The increase and d k The improvement of C k The larger the RFA k The smaller.

[0138] If a BIT report indicates a fault, the corresponding fault mode can be identified by reading flight data or history information. k The BIT feature is in the active state, at which point C k Set to 1, corresponding RFA k is 0.

[0139] 3.2.2) Series Dependency Case

[0140] If an "OR" logic combination appears in the aircraft health quantification model, resulting in a series dependency, then in a series configuration, the failure of a certain function i is attributed to an OR logic combination of multiple failure modes. That is, the occurrence of any one of the failure modes k will lead to the failure of function i.

[0141] The corresponding remaining functionality availability is represented as follows:

[0142]

[0143] Among them, C k Fault mode f k The degree of harm, n i Let be the number of fault modes corresponding to function i, and ∏() represent a continuous product;

[0144] 3.2.3) Parallel Dependency Case

[0145] If an AND logic combination appears in the aircraft health quantification model, resulting in parallel dependency, the failure of a certain function j is attributed to the AND logic combination of multiple failure modes. That is, the failure of function j will only occur if all failure modes combined by the AND logic combination occur. The corresponding remaining functional availability is represented as follows:

[0146]

[0147] Among them, C k Fault mode f k The degree of harm, n j The number of fault modes corresponding to function j;

[0148] 3.2.4) Voting relationship situation

[0149] If the system function is achieved by voting on the relevant outputs of its redundant components, then the voting relationship situation occurs, and the reliability analysis mode is adopted to evaluate the voting relationship;

[0150] 3.2.4.1) When all faults have not occurred, the RFA of function v is expressed as

[0151]

[0152] where the set {i, j,..., n f} has n - k elements, m is the normal function serial number, n is the total number of all functions, i is the serial number of the first failed function, j is the serial number of the second failed function, n f is the serial number of the n f th failed function, and distinct means that any two of them are different from each other;;;

[0153] 3.2.4.2) When l faults occur, 0 < l < n - l, the remaining n - l components form a voting form of taking k out of n - l, and the RFA of function v is expressed as

[0154]

[0155] where the set {i, j,..., n f} has n - l - k elements.

[0156] 3.2.4.3) When n - k faults occur, the remaining k components form a series-dependent relationship, and the RFA of function v is expressed as

[0157]

[0158] 3.2.4.4) When at least n - k + 1 faults occur, the RFA of function v is 0.

[0159] 3.3) Aircraft mission ability evaluation

[0160] According to the top-down structure provided by the aircraft health quantification model, collect fault information or system operation history information, obtain the aircraft-level function mission availability supported by each aircraft system / subsystem, conduct aircraft mission ability evaluation, and then complete the hierarchical aircraft health quantification process. The expression form of the function mission availability of mission M is:

[0161]

[0162] where N M represents the number of aircraft-level functions included in mission M, and RFA iIt is the remaining availability of one of the aircraft-level functions i, while w i This represents the weight of function i under that task; if it cannot be obtained, it is set to 1. The availability combinations of different tasks can be represented in the form of a radar chart (e.g., ...). Figure 10 (As shown).

Claims

1. A hierarchical method for quantifying aircraft health, comprising the following steps: Step 1) Based on the aircraft design information, obtain the hierarchical fault-functional logic of the aircraft. 1.1) The aircraft is divided into four levels: aircraft level, system level, subsystem level and LRU level. The complete functional division of the aircraft is reflected in different levels. 1.2) Establish the mapping relationship between the function of each level and its direct components, describe the impact of changes in the health of each layer on the mission / function-related capabilities, and realize top-down data collection and hierarchical health assessment to obtain the hierarchical fault-functional logic of the aircraft. Step 2) Construct a quantitative model of aircraft health based on the fault-function logical relationship. 2.1) Based on the loss of relevant functions of corresponding subsystem-level, system-level, and aircraft-level components caused by the failure of each LRU-level unit, construct an aircraft health quantification model; 2.2) Based on the loss of functions of other components at this level and the resulting loss of related functions of the corresponding higher-level components, construct a quantitative model of aircraft health; 2.3) Based on the requirements and the obtained design information, iteratively build a complete quantitative model of aircraft health by stepping through each level. Step 3) Based on the constructed aircraft health quantification model and aircraft history data, perform health quantification calculations. 3.1) Establish a general health assessment function A general health assessment function is used to perform health assessments on failure modes → functional failures at each level. Based on the Remaining Functional Availability (RFA) of the assessed object and the assessment requirements of different levels, a specific general health assessment function is generated using a hierarchical model. First, based on graphical modeling and data parsing, all levels of RFA are transformed into processing and analysis of the relationship between failure mode and functional failure. Then, according to different objects, the correspondence between function and failure is refined, and the final general health assessment function is expressed as follows: The variables in the above formula are explained as follows: H G —General health assessment values; RFA i —The first one contained in the object i The remaining functionality availability of each function; w i —No. i The weight of each function; N —The total number of functionalities contained in the object; 3.2) Calculate the remaining functionality availability based on four different scenarios. RFA i RFA i The determination should be limited by the specific logical relationship between the failure mode and the function, mainly including four cases: failure-function independence relationship, series dependency, parallel dependency and voting relationship; 3.3) Aircraft mission capability evaluation Based on the top-down structure provided by the aircraft health quantification model, fault information or system operation history information is collected to obtain the aircraft-level functional mission availability supported by each aircraft system / subsystem. Aircraft mission capability is then evaluated, thereby completing the hierarchical aircraft health quantification process. The functional mission availability of mission M is expressed as follows: in, N M Indicates task M The number of aircraft-level functions included. It is one of the aircraft-level functions i The remaining availability, and This refers to the function under this task. i The weight is set to 1 if it cannot be obtained.

2. The method as described in claim 1, wherein the division of functions for each level is obtained through FMECA and security analysis at each level.

3. The method as described in claim 2, characterized in that, "Direct components" refers to the next level of components at each level. At the aircraft level, the direct components are the various systems; at the system level, the direct components are the subsystems; and at the subsystem level, the direct components are the various units.

4. The method as described in claim 3, characterized in that, The specific manifestations of layered faults in aircraft functional logic are as follows: Aircraft level: The fault-function logic at this level is based on the relationship between the aircraft-level functional status and the health status of each system under the aircraft level. Specifically, the mapping relationship is expressed as the impact relationship between the functional failure of a system-level component and the functional failure of the aircraft level. The aircraft-level systems include airframe structure, flight-critical systems, and mission systems. The aircraft-level functions include in-flight environmental control, wing operation, in-flight refueling, aircraft control, and formation flying. System level: The fault - function logic at this level is established based on the relationship between the system - level function status and the health status of each subsystem subordinate to the system level. The specific mapping relationship should be expressed as the influence relationship of the failure of the component functions at the subsystem level → the failure of the system - level function; Among them, the subsystems subordinate to the mission system include ICP, network communication, integrated display and control, radio frequency, and optoelectronics. Among them, the functions of the mission system include radar detection, optoelectronic detection, CNI, integrated anti - interference, antenna / radio frequency integration, in - aircraft equipment communication, identification, route planning and coordination. Subsystem level: The fault - function logic at this level is established based on the relationship between the subsystem - level function and the health status of each LRU subordinate to the subsystem. The specific mapping relationship is expressed as the influence relationship of the abnormal health of the component parts at the LRU level → the failure of the subsystem - level function; Among them, the influence relationship of the failure of the ICDS function of the integrated display and control subsystem reflects the impact of the failure of the finished product on the subsystem function.

5. The method as described in claim 4, characterized in that, The corresponding information on the aircraft - level function status and the health status of each system subordinate to the aircraft level is obtained by collecting relevant design documents of the aircraft; the corresponding information on the system - level function status and the health status of each subsystem subordinate to the system level is obtained by collecting the corresponding design documents of the aircraft; the corresponding information on the function of each subsystem level and the health status of each LRU subordinate to the subsystem is obtained by collecting the corresponding design documents of the aircraft.

6. The method as described in claim 5, characterized in that, Step 2 In the aircraft health quantification model, through the setting of logic gates, the influence relationship of the loss of functions of different components between different levels or within the same level on the loss of functions of the upper - level function is determined.

7. The method as described in claim 6, characterized in that, The four different situations in step 3.2) are specifically as follows: 3.2.1) Function - independent situation If a functional failure in an aircraft health quantification model is attributed to only one failure mode, then in this case, it is assumed that the failure of function k is solely due to a single failure mode f. k Due to the occurrence of [something], the corresponding remaining functional availability in this case is: In the above formula, C k Fault mode f k The higher the hazard level, the lower the remaining functional availability, and the lower the overall system health assessment value obtained from this comprehensive assessment. 3.2.2) Series - dependent situation If an "or" logic combination appears in the aircraft health quantification model, a series - dependent situation occurs. In a series configuration, the failure of a certain function i is attributed to the "or" logic combination of multiple failure modes, that is, the occurrence of any one of the failure modes k will cause the failure of function i. The corresponding remaining function availability is expressed as follows: in, Fault mode f k The degree of harm, For function i The number of corresponding fault modes Indicates a continuous product; 3.2.3) Parallel - dependent situation If an "and" logic combination appears in the aircraft health quantification model, a parallel - dependent situation occurs. The failure of a certain function j is attributed to the "and" logic combination of multiple failure modes, that is, the failure of function j will occur only when all the failure modes combined by the "and" logic occur. The corresponding remaining function availability is expressed as follows: in, Fault mode f k The degree of harm, The number of fault modes corresponding to function j; 3.2.4) Voting - relationship situation If the system function is realized by voting on the relevant outputs of its redundant components, a voting - relationship situation occurs, and a reliability analysis model is used to evaluate the voting relationship; 3.2.4.1) When all faults have not occurred, the RFA of function v is expressed as Among them, set Total n - k There are three elements: m is the normal function index, n is the total number of functions, i is the index of the first failed function, and j is the index of the second failed function. For the first Each failed function has a unique serial number, where distinct numbers indicate that any two of them are different. 3.2.4.2) When l faults occur, 0 < l < n - l, the remaining n - l components form a voting form of taking k out of n - l, and the RFA of function v is expressed as Among them, set There are a total of nlk elements; 3.2.4.3) When it occurs n - k When there is a fault, the remaining k The components form a series dependency relationship, and their functions... v of RFA Expressed as 3.2.4.4) When at least n - k + 1 faults occur, the RFA of function v is 0.

8. The method as described in claim 7, characterized in that, In step 3.2.1) C k The specific value is obtained from the following two cases: If the failure mode does not occur, the focus is primarily on ready LRUs / LRMs that have already undergone offline maintenance. The severity of each failure mode is determined based on FMECA or FMECA. The corresponding remaining functional availability is ;in Fault mode f k The degree of harm, The failure rate for this failure mode can be obtained in FMECA. This represents the frequency ratio of fault occurrences. Use statistical values ​​from resume information and prior values ​​from FMECA; if these are unavailable, set to... =1, The impact of this failure mode is a measure of its ability to develop into functional failure, with a value range of 0 < ≤1, This refers to the runtime of the LRU / LRM to which the fault mode belongs, measured in flight hours. It is obtained by reading flight history information during pre-flight assessment and by accumulating flight mission time during post-flight assessment. It can be seen that, with... The increase and The improvement C k The larger, The smaller; If a BIT report indicates a fault, the corresponding fault mode can be identified by reading flight data or history information. k The BIT feature is in an active state. Set to 1, corresponding RFA k is 0.

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