A method for vehicle reliability modeling integrating on-orbit maintenance strategies

Abstract

A method for aircraft reliability modeling that integrates on-orbit maintenance strategies. First, a strategy scoring algorithm is used to determine the maintenance strategy of the on-orbit maintenance unit (ORU) to ensure that the maintenance strategy is reasonable and can effectively improve product reliability under limited resources. Second, according to different combinations of on-orbit maintenance units (ORU) maintenance strategies, the impact of different maintenance strategies on system reliability is identified, and the corresponding relationship between maintenance strategies and reliability modeling is determined. Finally, according to the judgment criteria for the corresponding relationship between maintenance strategies and reliability modeling, the ORU reliability modeling type is determined and incorporated into the system reliability model. The present invention clarifies the criteria for on-orbit maintenance strategies, and corresponds different maintenance strategies to reliability models one by one, so that the on-orbit maintenance strategies are incorporated into the reliability model, ensuring that the aircraft reliability model is comprehensive and effective, and laying the foundation for ensuring the effectiveness of the design scheme and carrying out subsequent reliability work.

Description

Technical Field

[0001] The present invention relates to an aircraft reliability modeling method integrating an on-orbit maintenance strategy, and is particularly suitable for an aircraft with an on-orbit maintenance capability. Background Art

[0002] As spacecraft's on-orbit operating time continues to increase, space station missions, for example, are now required to have a design life of no less than 15 years. To improve mission reliability, in addition to implementing multiple redundancy measures for key products, on-orbit maintenance is an important means of extending the service life of on-orbit repairable spacecraft and enhancing system reliability.

[0003] Compared to non-repairable products, repairable products require more research and development work and resources. For example, in addition to conventional product design verification, ORUs must meet ergonomic requirements, increase operator spacing and auxiliary facilities, and ensure safe and convenient electromechanical interface operation. They also require maintainability verification, with underwater testing being the most costly. Furthermore, planning for spare parts uploading and production is necessary. Therefore, developing reasonable on-orbit maintenance strategy criteria is essential for optimizing on-orbit maintenance plans, improving product reliability, and achieving optimal cost-effectiveness.

[0004] Through analysis, the current aircraft reliability model mainly considers the reliability of the aircraft's operating equipment (referred to as platform reliability), and does not include the product's maintainability in the modeling scope. It ignores the contribution of on-orbit maintenance spare parts to improving system reliability even though they do not participate in platform operation. It also fails to reflect the improvement effect of different maintenance strategies on system reliability, resulting in conservative system reliability assessment and possible waste of maintenance support resources. The aircraft reliability modeling method that integrates on-orbit maintenance strategies needs to solve the following problems:

[0005] 1) Comprehensively weigh product life characteristics, reliability design solutions, and the impact of failures to determine a reasonable on-orbit maintenance strategy;

[0006] 2) Organically combine the reliability of the operating system with the system maintainability, reflect the relationship between the original system redundancy design and the product maintainability design, and reflect it in the reliability modeling;

[0007] 3) Based on the system working mode, the differences in the improvement of system reliability by ORU of different maintenance types (preventive maintenance and corrective maintenance) are fully reflected, and the characteristics of preventive maintenance in advance are reflected in the reliability modeling;

[0008] 4) Based on the product impact and spare parts strategy, the difference in system reliability improvement between on-rail spare parts and ground spare parts is fully reflected, and the timeliness of on-rail spare parts is reflected in the reliability modeling. Summary of the Invention

[0009] The technical problem to be solved by the present invention is: to overcome the shortcomings of the existing technology and provide an aircraft reliability modeling method that integrates on-orbit maintenance strategies. First, the on-orbit maintenance equipment (ORU) maintenance strategy is determined by using a strategy scoring algorithm to ensure that the maintenance strategy is reasonable and can effectively improve product reliability under limited resources. Secondly, according to different combinations of on-orbit maintenance equipment (ORU) maintenance strategies, the impact of different maintenance strategies on system reliability is identified, and the corresponding relationship between maintenance strategies and reliability modeling is determined. Finally, according to the judgment criteria for the corresponding relationship between maintenance strategies and reliability modeling, the ORU reliability modeling type is determined and incorporated into the system reliability model. The present invention clarifies the on-orbit maintenance strategy criteria and corresponds different maintenance strategies to reliability models one by one, so that the on-orbit maintenance strategy is incorporated into the reliability model, ensuring that the aircraft reliability model is comprehensive and effective, laying the foundation for ensuring the effectiveness of the design plan and carrying out subsequent reliability work. It also reasonably reflects the contribution of on-orbit maintenance to improving product reliability and more objectively and accurately reflects the level of aircraft mission reliability.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A method for modeling aircraft reliability integrating on-orbit maintenance strategies includes the following steps:

[0012] Step 1: Determine the ORU maintenance strategy based on the ORU life characteristics, fault severity level, redundancy status, and life parameter characteristics;

[0013] Step 2: According to the ORU maintenance strategy and the corresponding relationship between the on-orbit maintenance strategy and the reliability model, the ORU reliability modeling type is determined;

[0014] Step 3: Based on the reliability modeling type determined in step 2, the reliability model is merged with the reliability model of the original operating system according to the parallel model or cold standby model to obtain a system reliability model that integrates the on-orbit maintenance strategy.

[0015] Furthermore, the ORU on-orbit maintenance strategy includes maintenance types and spare parts plans; maintenance types are divided into preventive maintenance and corrective maintenance; preventive maintenance is divided into planned maintenance and condition-based maintenance; ORU spare parts plans are divided into on-orbit spare parts, ground spare parts, and non-advance spare parts.

[0016] Furthermore, based on the ORU life characteristics, fault severity level, redundancy status, and life parameter characteristics, the ORU strategy score S value is calculated, and then the specific ORU maintenance strategy is determined;

[0017] The calculation method of the strategy score S value is:

[0018] S=α×β×γ+δ

[0019] Where: α represents the lifespan characteristics of the ORU, specifically:

[0020]

[0021] β represents the severity level of the ORU fault, specifically:

[0022]

[0023] γ represents the ORU redundancy status, specifically:

[0024]

[0025] δ characterizes the life parameter characteristics, specifically:

[0026]

[0027] According to the ORU strategy score S value, the method to determine the specific maintenance strategy of ORU is as follows:

[0028]

[0029] The maintenance type of the space station's solar panels and relay antennas is designated as corrective repair, and the spare parts plan is designated as no advance spare parts.

[0030] Furthermore, the fusion relationship is as follows:

[0031]

[0032]

[0033] Furthermore, the on-orbit maintenance strategy is incorporated into the reliability model based on three dimensions: maintenance type, redundancy status, and spare parts strategy.

[0034] Furthermore, the method for determining the ORU reliability modeling type is:

[0035] 1) When the ORU adopts a preventive maintenance strategy, and ground spare parts have been delivered to the aircraft before the product failure, and the aircraft operates normally before the faulty parts are repaired and replaced, without the need for consumption reduction or reduction, the ORU adopts a parallel model as a direct backup for the aircraft platform. The corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by the following criteria:

[0036]

[0037] Where f is a comprehensive function of various performance parameters of the normal operation of the aircraft;

[0038] X i-- Aircraft sealing and structural support performance parameters, control and propulsion performance parameters, thermal management performance parameters, cabin environment management performance parameters, energy management performance parameters, and information management performance parameters;

[0039] t0——the time when the ORU fault occurs;

[0040] t'0——the time when ORU prepares for maintenance;

[0041] R - aircraft platform reliability;

[0042] 2) When the ORU adopts a corrective maintenance strategy and adopts redundancy measures on-orbit, if there are spare parts on-orbit, the redundant backup machine will take over after the product fails, and the spacecraft will operate normally before the faulty part is repaired and replaced, without reducing consumption or configuration. The faulty product is replaced by the on-orbit spare part to complete the platform repair. In this case, the ORU adopts a parallel model as a direct backup for the operating system. The corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by the following criteria:

[0043]

[0044] Where λ min Indicates the minimum failure rate of the redundant functional modules implemented by the ORU;

[0045] 3) When the ORU adopts a corrective maintenance strategy and spare parts are stored on-orbit, and no backup redundancy measures are taken in the operating system, the faulty product is replaced by the on-orbit spare part after the product fails, and the platform can maintain operation in a safe mode or above before the faulty part is repaired and replaced, the ORU adopts the cold standby model. The corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by the following criteria:

[0046] f(t0;X1,X2,...,X n )>f(t′0;X1, X2,...,X n )>f min (X1, X2, ..., X n )

[0047] Where, f min It is a comprehensive function of various performance parameters of the aircraft's safe mode operation.

[0048] 4) When the ORU adopts a corrective maintenance strategy and a redundant design, if spare parts are available on the ground, the redundant backup machine will take over after a product failure, and the spacecraft will operate normally before the faulty part is repaired and replaced, without reducing consumption or configuration. After the ground spare parts are brought up, the faulty product will be replaced, completing the platform repair. In this case, the ORU adopts a parallel model as a direct backup for the operating system. The corresponding judgment criteria for the on-orbit maintenance strategy and reliability model are:

[0049]

[0050] 5) When the ORU adopts a corrective maintenance strategy and spare parts are available on the ground, no backup redundancy measures are taken in the operating system, and the ORU failure does not affect the platform operation, the ORU adopts the cold standby model. The criterion for determining the correspondence between the on-orbit maintenance strategy and the reliability model is to satisfy the following formula and the ORU is a non-platform reliability related product:

[0051]

[0052] 6) When the ORU adopts a corrective maintenance strategy but does not take redundancy measures and does not have on-orbit or ground spare parts, the ORU information is not reflected in the operational system reliability model.

[0053] Compared with the prior art, the present invention has the following beneficial effects:

[0054] (1) By comprehensively weighing the product life characteristics, reliability design schemes, and the degree of failure impact, a strategy scoring algorithm is proposed, which clarifies the quantitative design method of the on-orbit maintenance unit (ORU) maintenance strategy and its special cases, providing a clear basis for standardizing and optimizing the on-orbit maintenance strategy and laying the foundation for the rational planning of the spacecraft on-orbit operation plan;

[0055] (2) Incorporating on-orbit maintenance strategies into the reliability model from three dimensions, namely maintenance type, redundancy status, and spare parts strategy, quantitatively describes the differential impact of various on-orbit maintenance strategies on system reliability, significantly improving the level of refined reliability modeling of aircraft.

[0056] (3) On-orbit maintenance strategy criteria and the corresponding criteria between on-orbit maintenance strategy and reliability model provide quantitative criteria for comparing and optimizing reliability and maintainability design schemes for spacecraft and achieving the best cost-effectiveness.

[0057] (4) Establish an integrated relationship between on-orbit maintenance strategy and system reliability model. The ORU reliability model quantitatively reflects the contribution of product maintainability to system reliability, and more objectively and accurately reflects the mission reliability level of the aircraft, laying the foundation for ensuring the effectiveness of the aircraft design plan and carrying out subsequent reliability and maintainability work.

[0058] (5) By organically integrating product reliability and maintainability design, the original parallel development model of model reliability and maintainability has been changed, avoiding repeated iterations of model design, analysis, and verification and repeated investment of resources, and effectively improving the level of aircraft reliability and maintainability work. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is a step diagram of the aircraft reliability modeling method integrating on-orbit maintenance strategy of the present invention. DETAILED DESCRIPTION

[0060] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0061] A method for modeling the reliability of an aircraft that integrates an on-orbit maintenance strategy. The basic procedures of the method for modeling the reliability of an aircraft that integrates an on-orbit maintenance strategy include: determining the ORU maintenance strategy, determining the ORU reliability modeling type, and establishing a system reliability model. Figure 1 shown.

[0062] This paper refines the process from ORU maintenance strategy analysis to system reliability model establishment, combining the characteristics of on-orbit maintenance. The steps include:

[0063] Step 1: Determine the on-orbit maintenance unit (ORU) maintenance strategy, including ORU maintenance type and spare parts plan.

[0064] 1) ORU maintenance types include preventive maintenance and corrective maintenance. Preventive maintenance is performed before equipment failure occurs and is divided into planned maintenance and condition-based maintenance. Planned maintenance refers to the replacement of ORUs within a specified timeframe; condition-based maintenance refers to the timely and proactive replacement of ORUs based on measurable product performance degradation. Corrective maintenance refers to the replacement of ORUs after a product failure is detected.

[0065] 2) Spare parts strategies include on-orbit spares, ground spares, and non-preemptive spares. On-orbit spares refer to the long-term storage of at least one spare device within the aircraft. Ground spares refer to the storage of at least one spare device on the ground. In the event of an on-orbit failure, a spare part is brought up during the next mission to be replaced. Non-preemptive spares refer to the production and testing of spare parts after an on-orbit failure.

[0066] 3) The basic principle of the on-orbit maintenance strategy is: preventive maintenance is adopted for products whose lifespan does not meet the requirements of the spacecraft lifespan index, among which sudden failure ORUs adopt planned maintenance, and slowly decaying lifespan ORUs adopt condition-based maintenance; corrective maintenance is adopted for products whose lifespan meets the requirements of the spacecraft lifespan index for their criticality and redundancy status.

[0067] Formulate an on-orbit maintenance strategy, specifically according to the strategy score S value and strategy criteria specified in the present invention: determine the product life characteristics, reliability design scheme and fault impact information, calculate the strategy score S value according to formula (1), and determine the specific ORU maintenance strategy based on the S value according to the on-orbit maintenance strategy criteria listed in Table 1.

[0068] S=α×β×γ+δ (1)

[0069] Where: α represents the lifespan characteristics of the ORU, specifically:

[0070]

[0071] β represents the severity level of the ORU fault, specifically:

[0072]

[0073] γ represents the ORU redundancy status, specifically:

[0074]

[0075] δ characterizes the life parameter characteristics, specifically:

[0076]

[0077] Table 1

[0078]

[0079] 4) The rules listed in Table 2 do not apply to large critical spacecraft equipment. For example, for space station solar panels and relay antennas, the S values ​​are 2 and 3, respectively. However, due to on-orbit storage space constraints and the complex composition of these devices, if an on-orbit failure occurs, their status may change after reset, so spare parts are not pre-ordered.

[0080] Table 2

[0081]

[0082] Step 2: According to the ORU maintenance strategy and the corresponding judgment criteria between the on-orbit maintenance strategy and the reliability model, determine the ORU reliability modeling type.

[0083] 1) Collect ORU maintenance strategy information (maintenance type, spare parts plan), functional redundancy status and minimum failure rate; aircraft normal operation performance parameters, safety mode operation performance parameters, and system-level reliability model.

[0084] 2) Based on the criteria for the correspondence between on-orbit maintenance strategy and reliability model, analyze the impact of maintenance strategy on the aircraft's operating status and reliability, and determine the ORU reliability modeling type. Specific implementation is as follows:

[0085] a) When the ORU adopts a preventive maintenance strategy, and ground spare parts have been delivered to the aircraft before the product failure, and the aircraft operates normally before the faulty parts are repaired and replaced, without the need to reduce consumption or reduce configuration, the ORU adopts a parallel model as a direct backup for the aircraft platform. The corresponding criteria for the on-orbit maintenance strategy and reliability model are:

[0086]

[0087] Where f is a comprehensive function of various performance parameters of the normal operation of the aircraft;

[0088] X i -- Aircraft sealing and structural support performance parameters, control and propulsion performance parameters, thermal management performance parameters, cabin environment management performance parameters, energy management performance parameters, and information management performance parameters;

[0089] t0——the time when the ORU fault occurs;

[0090] t'0——the time when ORU prepares for maintenance;

[0091] R——aircraft platform reliability.

[0092] That is, the reliability of the aircraft platform before the ORU failure is the same as the reliability of the aircraft platform after the ORU failure but before repair, and the performance of each mission of the aircraft does not degrade before and after the failure;

[0093] b) When the ORU adopts a corrective maintenance strategy and adopts a redundant design, if there are spare parts on-orbit, the redundant backup machine will take over after the product fails, and the aircraft will operate normally before the faulty part is repaired and replaced, without reducing consumption or reducing configuration. The faulty product will be replaced by the on-orbit spare part to complete the platform repair. In this case, the ORU adopts a parallel model as a direct backup for the operating system. The corresponding judgment criteria for the on-orbit maintenance strategy and reliability model are:

[0094]

[0095] Where λ min Indicates the minimum failure rate of the redundant functional modules implemented by the ORU. That is, if the performance of each mission of the aircraft does not degrade before and after the failure, the minimum failure rate of the ORU redundant function will not change;

[0096] c) When the ORU adopts a corrective maintenance strategy and spare parts are stored on-orbit, and no backup redundancy measures are taken in the operating system, the faulty product is replaced by the on-orbit spare parts after the product fails, and the platform can maintain operation in a safe mode or above before the faulty part is repaired and replaced, the ORU adopts the cold standby model. The corresponding criteria for the on-orbit maintenance strategy and the reliability model are:

[0097] f(t0;X1,X2,...,X n )>f(t′0;X1, X2,...,X n )>f min (X1, X2, ..., X n ) (8)

[0098] Where, f min It is a comprehensive function of various performance parameters of the aircraft's safe mode operation.

[0099] d) When the ORU adopts a corrective maintenance strategy and adopts a redundant design, if there are spare parts on the ground, the redundant backup machine will be on duty after the product fails, and the aircraft will operate normally before the faulty part is repaired and replaced, without reducing consumption or reducing configuration. After the ground spare parts are uploaded, the faulty product is replaced and the platform repair is completed, the ORU adopts a parallel model as a direct backup for the operating system. The corresponding judgment criteria for the on-orbit maintenance strategy and reliability model are:

[0100]

[0101] e) When the ORU adopts a corrective maintenance strategy and spare parts are stored on the ground, and no backup redundancy measures are taken in the operating system, and the ORU failure does not affect the platform operation, the ORU adopts the cold standby model. The corresponding judgment criteria of the on-orbit maintenance strategy and the reliability model are to meet formula (10) and the ORU is a non-relevant product of the platform reliability:

[0102]

[0103] f) When the ORU adopts a corrective maintenance strategy and there are no on-orbit or ground spare parts, the ORU information is not reflected in the operating system reliability model.

[0104] Step 3: Incorporate ORU into the system reliability model

[0105] Based on the maintenance strategy determined in the first step and the ORU reliability modeling type determined in the second step, the parallel model and cold standby model (including the adapter) are combined with the reliability model of the original operating system to obtain a system reliability model that incorporates the on-orbit maintenance strategy. The fusion relationship is shown in Table 3 (Fusion relationship of the on-orbit maintenance strategy into the system reliability model).

[0106] Table 3

[0107]

[0108] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

[0109] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for modeling aircraft reliability integrating on-orbit maintenance strategy, characterized in that: The steps include: Step 1: Determine the maintenance strategy of the ORU based on the ORU life characteristics, fault severity level, redundancy status, and life parameter characteristics; Step 2: According to the ORU maintenance strategy, the ORU reliability modeling type is determined based on the judgment criteria of the correspondence between the on-orbit maintenance strategy and the reliability model; Step 3: According to the reliability modeling type determined in step 2, the reliability model of the original operating system is merged into a parallel model or a cold standby model to obtain a system reliability model integrating the on-orbit maintenance strategy; The ORU on-orbit maintenance strategy includes maintenance types and spare parts solutions; maintenance types are divided into preventive maintenance and corrective maintenance; preventive maintenance is divided into planned maintenance and condition-based maintenance; ORU spare parts solutions are divided into on-orbit spare parts, ground spare parts, and non-advance spare parts; The fusion relationship is as follows: The on-orbit maintenance strategy is incorporated into the reliability model based on three dimensions: maintenance type, redundancy status, and spare parts strategy.

2. The aircraft reliability modeling method according to claim 1, characterized in that: According to the ORU life characteristics, fault severity level, redundancy status, and life parameter characteristics, the ORU strategy score S value is calculated, and then the specific ORU maintenance strategy is determined; The calculation method of the strategy score S value is: S=α×β×γ+δ Where: α represents the life characteristics of ORU, specifically: β represents the severity level of ORU fault, specifically: γ represents the ORU redundancy status, specifically: δ characterizes the life parameter characteristics, specifically: According to the ORU strategy score S value, the method to determine the specific maintenance strategy of ORU is: The maintenance type for the space station's solar panels and relay antennas is designated as corrective repair, and the spare parts plan is designated as no advance spare parts.

3. The aircraft reliability modeling method according to claim 1, characterized in that: The method to determine the ORU reliability modeling type is: 1) When the ORU adopts a preventive maintenance strategy, and the ground spare parts have been delivered to the aircraft before the product fails, and the aircraft operates normally before the faulty parts are repaired and replaced, and there is no need to reduce consumption and configuration, the ORU adopts a parallel model as a direct backup for the aircraft platform; the corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by: Where f is a comprehensive function of various performance parameters of the normal operation of the aircraft; X i ——Aircraft sealing and structural support performance parameters, control and propulsion performance parameters, thermal management performance parameters, cabin environment management performance parameters, energy management performance parameters, and information management performance parameters; t0——the time when the ORU failure occurs; t'0——the time when ORU prepares for maintenance; R——aircraft platform reliability; 2) When the ORU adopts a corrective maintenance strategy and takes redundant measures on-orbit, if there are spare parts on-orbit, the redundant backup machine will work on duty after the product fails, and the aircraft will operate normally before the faulty parts are repaired and replaced, without reducing consumption and configuration. The faulty product is replaced by the on-orbit spare parts to complete the platform repair. In this case, the ORU adopts a parallel model as a direct backup for the operating system; the corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by: In the formula, λ min Indicates the minimum failure rate of the redundant functional modules implemented by the ORU; 3) When the ORU adopts a corrective maintenance strategy and spare parts are stored on-orbit, and no backup redundancy measures are taken in the operating system, the faulty product is replaced by the on-orbit spare parts after the product fails, and the platform can maintain operation in a mode not lower than the safe mode before the faulty part is repaired and replaced, then the ORU adopts the cold standby model; the corresponding relationship between the on-orbit maintenance strategy and the reliability model is determined by the following criteria: f(t0;X1,X2,...,X n )>(t′0;X1,X2,...,X n )>f min (X1,X2,...,X n ) In the formula, f min It is a comprehensive function of various performance parameters of the aircraft's safe mode operation; 4) When the ORU adopts a corrective maintenance strategy and a redundant design, if there are spare parts on the ground, the redundant backup machine will work on duty after the product fails, and the aircraft will operate normally before the faulty parts are repaired and replaced, without reducing consumption and configuration. After the ground spare parts are uploaded, the faulty product is replaced to complete the platform repair. In this case, the ORU adopts a parallel model as a direct backup of the operating system; the corresponding judgment criteria for the on-orbit maintenance strategy and the reliability model are: 5) When the ORU adopts a corrective maintenance strategy and there are spare parts on the ground, and no backup redundancy measures are taken in the operating system, and the failure of the ORU does not affect the platform operation, the ORU adopts a cold standby model; the criterion for the corresponding relationship between the on-orbit maintenance strategy and the reliability model is to satisfy the following formula and the ORU is a non-relevant product for platform reliability: 6) When the ORU adopts a corrective maintenance strategy but does not take redundant measures and does not have on-orbit or ground spare parts, the ORU information is not reflected in the operating system reliability model.

Images