Aircraft health evaluation method based on functional ladder

Abstract

The invention discloses an aircraft health evaluation method based on a function ladder. The method comprises the following steps: 1) dividing complete functions of an aircraft into different levels; the hierarchy is divided into an aircraft hierarchy, a system hierarchy, a subsystem hierarchy and a subsystem hierarchy; 2) designing a functional ladder; a safety / reliability analysis document, a function harmfulness analysis (FHA) document and a fault mode and influence analysis (FMEA) document are sorted out in the form of a table or a fault tree to obtain a mapping relation between functions of each layer of an aircraft and composition health changes of each layer, and function ladder design is completed; 3) establishing a health evaluation model; and establishing a layered health evaluation model according to the mapping relationship in the function ladder. According to the aircraft health evaluation method based on the function ladder, complex system health evaluation based on the function ladder faces task requirements, an aircraft serves as a final evaluation object, and quantification of health evaluation is completed from bottom to top from an outfield replaceable unit.

Description

Technical Field

[0001] The invention relates to an overall aircraft health assessment technology, and in particular to an aircraft health assessment method based on a functional ladder. Background Art

[0002] The functional ladder refers to the functional decomposition method of the aircraft. The aircraft is taken as the final evaluation object through the functional decomposition of the aircraft. The reliability, life, maintainability, testability, safety and usage data are integrated to complete the health evaluation from the bottom up from the field replaceable unit / module level. It can be expanded from the local to the overall, completing the overall health assessment of the aircraft, which serves as an important basis for the release of the aircraft. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide an aircraft health evaluation method based on a functional ladder in view of the defects in the prior art.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] An aircraft health assessment method based on a functional ladder comprises the following steps:

[0006] 1) The complete functions of the aircraft are divided into different levels; the levels are divided into four levels: aircraft level, system level, subsystem level and subsystem level;

[0007] The aircraft class is an aircraft;

[0008] The system level includes airframe structure system, aircraft system, mission system and cockpit system;

[0009] The subsystem level is the functional module of each system in the system level;

[0010] The subsystem level refers to each functional component or functional submodule of the subsystem level functional module;

[0011] 2) Design functional ladders;

[0012] By sorting out the safety / reliability analysis documents, functional hazard analysis FHA documents and failure mode and effect analysis FMEA documents, the mapping relationship between the functions of each layer of the aircraft and the healthy changes of each layer's components is obtained in the form of tables or fault trees, and the functional ladder design is completed;

[0013] Each level establishes a mapping relationship between its own functions and the health changes of the components of each level;

[0014] Changes in the health of each layer’s components include failures and abnormal events;

[0015] The mapping relationship of each level is the impact relationship between the failure of each level component and the failure of the corresponding level function;

[0016] Aircraft-level mapping is based on the relationship between aircraft-level functional status and the health status of each system under the aircraft. The main systems of the aircraft include the body structure, aircraft, mission and cockpit systems. Aircraft-level functions include in-flight environment control, wing actuation, aerial refueling, aircraft control, formation flying, and attack functions in different scenarios.

[0017] This type of information can be obtained by collecting relevant design documents. The specific mapping relationship should be expressed as the impact relationship between system-level component failures and aircraft-level functional failures;

[0018] System-level mapping should be based on the relationship between system functions and the health status of the subsystems that make up the system. The specific corresponding information between each system function and subsystem can be obtained by referring to the corresponding design documents. The specific mapping relationship should be expressed as the impact of component (subsystem) failure and system-level function failure.

[0019] Subsystem mapping should be based on the relationship between subsystem functions and the health status (fault or abnormality) of subsystem components (subsystem / finished product). The specific mapping relationship should be expressed as the impact relationship between component (subsystem / finished product) failure and subsystem-level functional failure;

[0020] Subsystem mapping is based on the relationship between subsystem functions and the health status of the functional modules that make up the subsystem. The specific mapping relationship should be expressed as the impact relationship between the component line replaceable unit LRU failure and the subsystem level function failure;

[0021] 3) Establish a health assessment model;

[0022] A hierarchical health evaluation model is established based on the mapping relationship in the function ladder. In the hierarchical health evaluation model, the attribution relationship between LRU-level failures and the corresponding aircraft functional failures at each level is directly established according to the different requirements for the evaluated level. The evaluation function is as follows:

[0023]

[0024] in,

[0025] H G is the health evaluation value;

[0026] RFA i To evaluate the remaining functional availability of the i-th function contained in the hierarchical object;

[0027] W i is the weight of the i-th function;

[0028] N is the total number of functions included in the evaluation level objects;

[0029] Among them, RFA iThe determination is limited according to the specific logical relationship between health abnormality and function, and the logical relationship includes four situations: independent relationship, series dependency, parallel dependency and voting relationship;

[0030] 3.1) Health abnormalities and functions are independent of each other;

[0031] In the hierarchical aircraft health assessment model, when the functional failure is attributed to only one failure mode, it is assumed that the failure of function k is only due to one failure mode f. k The corresponding residual functional availability in this case is:

[0032] RFA k =1-C k ;

[0033] In the formula, C k Fault mode f k The greater the value, the smaller the residual function availability, and the lower the system health evaluation value obtained by the comprehensive evaluation; C k The specific definition of needs to be obtained according to different situations.

[0034] 3.1.1) Evaluation when the failure mode has not occurred, mainly for the ready LRU that has completed offline maintenance, and obtain the criticality of different failure modes based on FMECA. FMECA includes two parts: failure mode and effect analysis and criticality analysis;

[0035] Right now

[0036] C k =λ k d k β k t LRU

[0037] The corresponding remaining functional availability is

[0038] RFA k =1-λ k d k β k t LRU ;

[0039] Among them C k Fault mode f k The criticality, λ k is the failure rate of this failure mode, which can be obtained in FMECA, d k is the failure frequency ratio, which can be obtained by using the statistical value in the historical information and the prior value in FMECA. If it cannot be obtained, it can be set to 1. k is the impact of the failure mode, that is, the ability of the failure to develop into functional failure, and its value range is 0<β k≤1 (usually 1), can also be obtained through FMECA, t LRU is the running time (in flight hours) of the LRU to which the fault mode belongs. It can be obtained by reading the flight history information during pre-flight evaluation and by accumulating the flight mission time during post-flight evaluation. It can be seen that with the running time t LRU The increase and d k The improvement of k The larger the RFA k The smaller;

[0040] 3.1.2) When a fault occurs (BIT fault, parameter limit exceeded, life-limited component failure, etc.), the corresponding fault mode is found by reading the flight data information or history information. k The characteristic quantity (BIT, monitoring parameter) is in the activated state (BIT is set, monitoring parameter exceeds the limit, etc.). At this time, C k Set to 1. The corresponding RFAk is 0.

[0041] If the running time is long, resulting in C k >1, the evaluation algorithm should use C k Set to 1. Then the corresponding RFA k Then it is 0.

[0042] 3.2) The health abnormality and function are in a serial dependency relationship;

[0043] In the hierarchical aircraft health assessment model, the failure of a function is the "OR" logical combination of multiple failure modes. The serial dependency situation is solved by a method that has been commonly used in reliability modeling and analysis. In the serial configuration, the failure of a function i can be attributed to the OR logical 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.

[0044] The corresponding residual functional availability is expressed as follows:

[0045]

[0046] Among them, C k Fault mode f k The degree of hazard, n i is the number of failure modes corresponding to function i;

[0047] When the failure mode does not occur,

[0048] C k =λ k d k β k t LRU / LRM ;

[0049] With the running time tLRU The increase and d k The improvement of C k The larger the RFA i The smaller it is, and because of the series dependence, RFA i The deterioration will be more severe;

[0050] When a certain failure mode f corresponding to function i k When a fault occurs (BIT is set, monitoring parameters exceed the limit, etc.), the corresponding C k Set to 1, then RFA i =0.

[0051] 3.3) Parallel dependence situation.

[0052] In the hierarchical aircraft health assessment model, when the functional failure is the AND logic combination of multiple fault modes, the failure of a function j can be attributed to the AND logic combination of multiple fault modes, that is, all the fault modes of the AND logic combination must occur to cause the failure of function j. For example, the power supply function in the propulsion subsystem (FCS) has left and right engine backups, which are typical reflections of this situation on the evaluation object. The corresponding residual functional availability is expressed as follows:

[0053]

[0054] Among them, C k Fault mode f k The degree of hazard, n j is the number of failure modes corresponding to function j;

[0055] When the failure mode does not occur, C k =λ k d k β k t LRU / LRM . As the running time t LRU The increase and d k The improvement of Ck is larger, and RFA i The smaller it is, and because of the parallel dependence, RFA i The deterioration of function i is more moderate than that of independent and series connection. k When a fault occurs (BIT is set, monitoring parameters exceed the limit, etc.), the corresponding C k Set to 1, when all fault modes occur, RFA i =0.

[0056] 3.4) Voting relationship.

[0057] Voting situations generally occur when certain system functions are achieved by voting on the relevant outputs of their redundant components. The most typical form of a voting system is k out of n, that is, when k or more than k of the n components are working properly, the system works properly. In other words, when at least n - k + 1 components fail, the system fails. This type of situation often appears in the combination of redundant flight control-related sensor units or computing units, such as the voting relationship of the 4 flight management computers in the VMS in terms of control law solution.

[0058] The evaluation of the voting relationship is relatively complex and can be evaluated using a reliability analysis model. The discussion is as follows:

[0059] 1) When no failures occur, the RFA of function v is expressed as

[0060]

[0061] where the set {i, j, …, n f} has n - k elements.

[0062] 2) When l failures occur (0 < l < n - l), the remaining n - l components form a k out of n - l voting form, and the RFA of function v is expressed as

[0063]

[0064] where the set {i, j, …, n f} has n - l - k elements.

[0065] When n - k failures occur, the remaining k components form a series-dependent relationship, and the RFA of function v is expressed as:

[0066]

[0067] When at least n - k + 1 failures occur, the RFA of function v is 0.

[0068] The beneficial effects produced by the present invention are:

[0069] The aircraft health evaluation method based on the function ladder of the present invention, the health evaluation of the complex system based on the function ladder is oriented to mission requirements, takes the aircraft as the final evaluation object, and completes the quantification of the health evaluation from the bottom up of the line replaceable units in the field. The health evaluation results can be used as an important basis for the aircraft to take off, and can be compared horizontally with the health conditions of different aircraft in the fleet to provide a reference for reasonably selecting combat aircraft. Description of the Drawings

[0070] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0071] Figure 1 is a method flow chart of an embodiment of the present invention;

[0072] Figure 2 Schematic diagram of the division of each layer of an aircraft system according to an embodiment of the present invention;

[0073] Figure 3 is a mapping relationship table between aircraft-level functions and system components of an embodiment of the present invention;

[0074] Figure 4 is a mapping relationship table between the system-level (task system) composition and subsystem functions of the embodiment of the present invention;

[0075] Figure 5 It is a subsystem-level composition and function mapping relationship table of an embodiment of the present invention. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0077] like Figure 1 As shown, a method for evaluating aircraft health based on a functional ladder includes the following steps:

[0078] 1) The complete functions of the aircraft are divided into different levels; the levels are divided into four levels: aircraft level, system level, subsystem level and subsystem level;

[0079] The aircraft class is an aircraft;

[0080] The system level includes airframe structure system, aircraft system, mission system and cockpit system;

[0081] The subsystem level is the functional module of each system in the system level;

[0082] The subsystem level refers to each functional component or functional submodule of the subsystem level functional module;

[0083] 2) Design functional ladders;

[0084] By sorting out the safety / reliability analysis documents, functional hazard analysis FHA documents and failure mode and effect analysis FMEA documents, the mapping relationship between the functions of each layer of the aircraft and the healthy changes of each layer's components is obtained in the form of tables or fault trees, and the functional ladder design is completed;

[0085] Each level establishes a mapping relationship between its own functions and the health changes of the components of each level;

[0086] Changes in the health of each layer’s components include failures and abnormal events;

[0087] The mapping relationship of each level is the impact relationship between the failure of each level component function and the failure of the corresponding level function.

[0088] Aircraft-level mapping is based on the relationship between aircraft-level functional status and the health status of each system under the aircraft. The main systems of the aircraft include the body structure, aircraft, mission and cockpit systems. Aircraft-level functions include in-flight environment control, wing actuation, aerial refueling, aircraft control, formation flying, and attack functions in different scenarios.

[0089] This type of information can be obtained by collecting relevant design documents. For specific mapping, see Figure 3 As shown in the figure, "AV-XX" is the aircraft-level function number. The specific mapping relationship should be expressed as the impact relationship between component (system-level) function failure and aircraft-level function failure.

[0090] System-level mapping should be based on the relationship between system functions and the health status of system components (subsystems). Taking the mission system as an example, its subsystem components may include integrated processing system (IMS), data management and recording system (DMRS), satellite navigation (IN), etc. The corresponding functions include radar detection, optoelectronic detection, CNI, integrated electronic warfare, antenna / RF integration, in-flight equipment communication, beyond-visual-range identification and tracking, close-range identification and tracking, route planning and coordination, situational awareness, weapon delivery, etc. The specific corresponding information of each system function and subsystem can be obtained by referring to the corresponding design documents, and the mapping diagram can be seen. Figure 4 , where "MS-XX" is the mission system function number. The specific mapping relationship should be expressed as the impact of component (subsystem) function failure and system-level function failure;

[0091] Subsystem mapping should be based on the relationship between subsystem functions and the health status (fault or abnormality) of subsystem components (subsystem / finished product). Taking the integrated data management and recording system as an example, it includes functions DMRS_01 to DMRS_27, and the failure modes of the finished products to which it belongs can be marked as DMRS_F01 to DMRS_F66. This layer of function ladder should be able to reflect the impact of finished product failures on subsystem functions. Specific information on the corresponding subsystem functions and subsystem failures can be obtained by referring to the corresponding design documents, and the mapping diagram can be seen Figure 5 , "DMRS-XX" in the figure is the function number of the integrated display and control system. The specific mapping relationship should be expressed as the impact relationship between the abnormal health (fault or failure) of the component (subsystem / finished product) and the subsystem-level functional failure;

[0092] The subsystem also includes subsystems. For example, the flight control subsystem is further divided into the atmospheric data subsystem, inertial sensor subsystem, servo actuation subsystem, longitudinal / heading / lateral control subsystem, etc. The mapping of this type of system can first establish the composition and function mapping between the subsystem and the subsystem, and then establish the composition and function mapping between the subsystem and the line replaceable unit LRU.

[0093] 3) Establish a health assessment model;

[0094] Through the mapping relationship of the function ladder, a logic matrix is ​​generated, including: the reachable matrix of fault and functional failure and the adjacency matrix, so as to generate the sign vector and function to be evaluated. The former characterizes the attribution relationship between fault and functional failure, and the latter is the evaluation function of the function obtained according to the sign vector. This process can be completed by the corresponding analytical tool developed by MATLAB.

[0095] Depending on the requirements of the evaluation level, functional failures can use different levels of functions. For example, when evaluating aircraft-level health, the attribution relationship between LRU-level failures and aircraft-level functional failures is directly established. If the finished product (LRU-level) health is evaluated, the attribution relationship between LRU-level failures and LRU-level local functional failures is directly established.

[0096] The attribution relationship between faults and functional failures is represented by vectors, and the corresponding evaluation function is generated by combining the logical relationship between attribution of faults to functional failures.

[0097] A hierarchical health evaluation model is established based on the mapping relationship in the function ladder. In the hierarchical health evaluation model, the attribution relationship between LRU-level failures and the corresponding aircraft functional failures at each level is directly established according to the different requirements for the evaluated level. The evaluation function is as follows:

[0098]

[0099] in,

[0100] H G is the health evaluation value;

[0101] RFA i To evaluate the remaining functional availability of the i-th function contained in the hierarchical object;

[0102] W i is the weight of the i-th function;

[0103] N is the total number of functions included in the evaluation level objects;

[0104] Among them, RFA i The determination is limited according to the specific logical relationship between health abnormality and function, and the logical relationship includes four situations: independent relationship, series dependency, parallel dependency and voting relationship;

[0105] 3.1) Health abnormalities and functions are independent of each other;

[0106] In the hierarchical aircraft health assessment model, when the functional failure is attributed to only one failure mode, it is assumed that the failure of function k is only due to one failure mode f. k The corresponding residual functional availability in this case is:

[0107] RFA k =1-C k ;

[0108] In the formula, C k Fault mode f k The greater the value, the smaller the residual function availability, and the lower the system health evaluation value obtained by the comprehensive evaluation; C k The specific definition of needs to be obtained according to different situations.

[0109] 3.1.1) Evaluation when the failure mode has not occurred, mainly for the ready LRU that has completed offline maintenance, and obtain the criticality of different failure modes based on FMECA. FMECA includes two parts: failure mode and effect analysis and criticality analysis;

[0110] Right now

[0111] C k =λ k d k β k t LRU

[0112] The corresponding remaining functional availability is

[0113] RFA k =1-λ k d k β k t LRU ;

[0114] Among them C k Fault mode f k The criticality, λ k is the failure rate of this failure mode, which can be obtained in FMECA, d k is the failure frequency ratio, which can be obtained by using the statistical value in the historical information and the prior value in FMECA. If it cannot be obtained, it can be set to 1. k is the impact of the failure mode, that is, the ability of the failure to develop into functional failure, and its value range is 0<β k ≤1 (usually 1), can also be obtained through FMECA, t LRUis the running time (in flight hours) of the LRU to which the fault mode belongs. It can be obtained by reading the flight history information during pre-flight evaluation and by accumulating the flight mission time during post-flight evaluation. It can be seen that with the running time t LRU The increase and d k The improvement of k The larger the RFA k The smaller;

[0115] 3.1.2) When a fault occurs (BIT fault, parameter limit exceeded, life-limited component failure, etc.), the corresponding fault mode is found by reading the flight data information or history information. k The characteristic quantity (BIT, monitoring parameter) is in the activated state (BIT is set, monitoring parameter exceeds the limit, etc.). At this time, C k Set to 1. The corresponding RFAk is 0.

[0116] If the running time is long, resulting in C k >1, the evaluation algorithm should use C k Set to 1. Then the corresponding RFA k Then it is 0.

[0117] 3.2) The health abnormality and function are in a serial dependency relationship;

[0118] In the hierarchical aircraft health assessment model, the failure of a function is the "OR" logical combination of multiple failure modes. The serial dependency situation is solved by a method that has been commonly used in reliability modeling and analysis. In the serial configuration, the failure of a function i can be attributed to the OR logical 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.

[0119] The corresponding residual functional availability is expressed as follows:

[0120]

[0121] Among them, C k Fault mode f k The degree of hazard, n i is the number of failure modes corresponding to function i;

[0122] When the failure mode does not occur,

[0123] C k =λ k d k β k t LRU / LRM ;

[0124] With the running time t LRU The increase and d k The improvement of Ck The larger the RFA i The smaller it is, and because of the series dependence, RFA i The deterioration will be more severe;

[0125] When a certain failure mode f corresponding to function i k When a fault occurs (BIT is set, monitoring parameters exceed the limit, etc.), the corresponding C k Set to 1, then RFA i =0.

[0126] 3.3) Parallel dependence situation.

[0127] In the hierarchical aircraft health assessment model, when the functional failure is the AND logic combination of multiple fault modes, the failure of a function j can be attributed to the AND logic combination of multiple fault modes, that is, all the fault modes of the AND logic combination must occur to cause the failure of function j. For example, the power supply function in the propulsion subsystem (FCS) has left and right engine backups, which are typical reflections of this situation on the evaluation object. The corresponding residual functional availability is expressed as follows:

[0128]

[0129] Among them, C k Fault mode f k The degree of hazard, n j is the number of failure modes corresponding to function j;

[0130] When the failure mode does not occur, C k =λ k d k β k t LRU / LRM . As the running time t LRU The increase and d k The improvement of Ck is larger, and RFA i The smaller it is, and because of the parallel dependence, RFA i The deterioration of function i is more moderate than that of independent and series connection. k When a fault occurs (BIT is set, monitoring parameters exceed the limit, etc.), the corresponding C k Set to 1, when all fault modes occur, RFA i =0.

[0131] 3.4) Voting relationship.

[0132] Voting generally occurs when certain system functions are achieved by voting on the relevant outputs of their redundant components. The most typical form of the voting system is k out of n, that is, when k or more than k of the n components are working properly, the system works properly. In other words, when at least n - k + 1 components fail, the system fails. This kind of situation often appears in the combination of redundant flight control-related sensor units or computing units, such as the voting relationship of 4 flight management computers in the VMS in terms of control law solution.

[0133] The evaluation of the voting relationship is relatively complex and can be evaluated using the reliability analysis model. The discussion is as follows:

[0134] 3.4.1) When all faults do not occur, the RFA of function v is expressed as

[0135]

[0136] where the set {i, j, …, n f} has n - k elements.

[0137] 3.4.2) When l faults occur (0 < l < n - l), the remaining n - l components form a k out of n - l voting form, and the RFA of function v is expressed as

[0138]

[0139] where the set {i, j, …, n f} has n - l - k elements.

[0140] When n - k faults occur, the remaining k components form a series-dependent relationship, and the RFA of function v is expressed as:

[0141]

[0142] When at least n - k + 1 faults occur, the RFA of function v is 0.

[0143] After the aircraft health assessment is completed, according to the top-down structure provided by the hierarchical aircraft health assessment model, fault information or system operation history information is collected to obtain the comprehensive availability of aircraft-level functions supported by each aircraft system / subsystem. Based on this, the mission availability needs to establish the relationship between different missions and aircraft-level functions to be obtained. Therefore, it needs to be further refined in the subsequent modeling process (m is the number of aircraft-level functions required by the aircraft under a specific mission). The expression form of the availability of mission M can be initially determined as:

[0144]

[0145] where N MRepresents the number of aircraft-level functions included in task M, RFA i is the residual availability of one of the aircraft-level functions i, and w i is the weight of function i under this task, and is set to 1 if it cannot be obtained.

[0146] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. An aircraft health assessment method based on a functional ladder, characterized in that: The following steps are involved: 1) The complete functions of the aircraft are divided into different levels; the levels are divided into four levels: aircraft level, system level, subsystem level and subsystem level; The aircraft class is an aircraft; The system level includes airframe structure system, aircraft system, mission system and cockpit system; The subsystem level is the functional module of each system in the system level; The subsystem level refers to each functional component or functional unit of the subsystem level functional module; 2) Design functional ladders; By sorting out the safety / reliability analysis documents, functional hazard analysis FHA documents and failure mode and effect analysis FMEA documents, the mapping relationship between the functions of each layer of the aircraft and the healthy changes of each layer's components is obtained in the form of tables or fault trees, and the functional ladder design is completed; Each level establishes a mapping relationship between its own functions and the health changes of the components of each level; Changes in the health of each layer’s components include failures and abnormal events; The mapping relationship of each level is the impact relationship between the failure of the component functions of each level and the failure of the corresponding level functions; 3) Establish a health assessment model; A hierarchical health evaluation model is established based on the mapping relationship in the function ladder, and the evaluation function is as follows: in, H G is the health evaluation value; RFA i To evaluate the remaining functional availability of the i-th function contained in the hierarchical object; W i is the weight of the i-th function; N is the total number of functions included in the evaluation level objects; Among them, RFA i The determination is limited according to the specific logical relationship between health abnormalities and functions. The logical relationship includes four situations: independent relationship, series dependency, parallel dependency and voting relationship.

2. The aircraft health assessment method based on functional ladder according to claim 1 is characterized in that: In step 2), the mapping relationship between the functions of each layer of the aircraft and the health changes of each layer composition is as follows: Aircraft-level mapping is based on the relationship between aircraft-level functional status and the health status of each system under the aircraft. The aircraft system includes the airframe structure system, aircraft system, mission system and cockpit system. Aircraft-level functions include in-flight environment control, wing actuation, aerial refueling, aircraft control, formation flying, and attack functions in different scenarios. The specific mapping relationship is expressed as the impact relationship between component failure and aircraft-level function failure. System-level mapping is based on the relationship between system functions and the health status of the subsystems that make up the system. The corresponding information between each system function and subsystem can be obtained through the design documents. The specific mapping relationship should be expressed as the impact of component failure and system-level function failure. Subsystem mapping is based on the relationship between subsystem functions and the health status of the functional modules that make up the subsystem. The specific mapping relationship should be expressed as the impact relationship between component failure and subsystem-level functional failure; Subsystem mapping is established on the relationship between subsystem functions and the health status of the functional modules that make up the subsystem. The specific mapping relationship should be expressed as the impact relationship between the component line replaceable unit (LRU) failure and the subsystem level function failure.

3. The aircraft health assessment method based on the function ladder according to claim 1 is characterized in that the residual function availability of the function is calculated as follows: 3.1) Health abnormalities and functions are independent of each other; In the hierarchical aircraft health assessment model, when the functional failure is attributed to only one failure mode, it is assumed that the failure of function i is only due to one failure mode f k The corresponding residual functional availability in this case is: RFA i =lC k ; In the formula, C k Fault mode f k degree of hazard; Hazard C k The points are obtained; 3.1.1) Evaluation when the failure mode has not occurred, mainly for the ready LRU that has completed offline maintenance, and obtain the criticality of different failure modes based on FMECA. FMECA includes two parts: failure mode and effect analysis and criticality analysis; Right now C k =λ k d k β k kt LRU ; The corresponding remaining functional availability is RFA k =1-λ k d k b k t LRU ; Among them, C k Fault mode f k The criticality, λ k is the failure rate of this failure mode, obtained in FMECA, d k is the fault occurrence frequency ratio, β k is the impact of the failure mode, that is, the ability of the failure to develop into functional failure, t LRU is the running time of the LRU to which the failure mode belongs; 3.1.2) When a fault occurs, C k Set to 1, the corresponding RFA i is 0; 3.2) The health abnormality and function are in a serial dependency relationship; In the hierarchical aircraft health assessment model, when the functional failure is the "OR" logical combination of multiple failure modes, the corresponding residual functional availability is expressed as follows: Among them, C k Fault mode f k The degree of hazard, n i is the number of failure modes corresponding to function i; When the fault mode does not occur, C k =λ k d k b k t LRU / LRM ; When a certain failure mode f k C k Set to 1, then RFA i =0; 3.3) The case where health abnormality and function are in a parallel dependence relationship; In the hierarchical aircraft health assessment model, when the function failure is a "AND" logical combination of multiple fault modes, the failure of a certain function j is attributed to the AND logical combination of multiple fault modes, that is, the failure of function j will occur only when all the fault modes combined by "AND" occur. The available degree of the corresponding remaining function is expressed as follows: Among them, C k Fault mode f k The degree of hazard, n j is the number of failure modes corresponding to function j; When the failure mode does not occur, C k =λ k d k β k t LRU / LRM ; When a certain failure mode f corresponding to function i k When this happens, the corresponding C k Set to 1, when all fault modes occur, RFA i =0. 3.4) The case where health abnormality and function are in a voting relationship; The voting situation generally occurs when some system functions are realized by voting on the relevant outputs of their redundant components. The voting system form is k out of n, that is, when k or more than k of the n components work normally, the system works normally; The voting relationship is evaluated by using the reliability analysis mode, specifically as follows: 3.4.1) When all faults do not occur, the RFA of function v is expressed as Among them, the set {i,j,…,n f }There are nk elements in total. 3.4.2) When l faults occur, 0 < l < n - l, the remaining n - l components form a voting form of (n - l) out of k, and the RFA of function v is expressed as in, The set {i,j,…,n f }There are nlk elements in total; When n - k faults occur, the remaining k components form a series dependence relationship, and the RFA of function v is expressed as: When at least n - k + 1 faults occur, the RFA of function v is 0.

4. An electronic device, characterized in that it includes: one or more processors; and a storage device for storing one or more programs, wherein, when the one or more programs are executed by the one or more processors, the one or more processors are caused to execute the method according to any one of claims 1 to 3.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: The computer program, when executed by a processor, implements the method according to any one of claims 1 to 3.

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