System reliability distribution method and device

Abstract

The invention discloses a system reliability distribution method and device, and belongs to the technical field of reliability design. The method comprises the following steps: defining a system architecture and carrying out reliability modeling and fault tree analysis; calculating to obtain an expression of the occurrence probability of the top event, and determining the target reliability of system reliability distribution; according to the probability importance degree expression of each component, calculating the structure importance degree and the system reliability change gradient; and constructing a target optimization model according to the structural importance, the system reliability change gradient and the like, executing target optimization iterative calculation, and determining a system reliability distribution result based on the component importance and the reliability change gradient. According to the system reliability distribution method, the component importance information is fully utilized to perform system reliability distribution, and the system reliability distribution method provided by the invention can ensure that the fluctuation amplitude along with the change of the component reliability is minimum, and accords with a system reliability distribution principle that the components with high key importance should be distributed with relatively high reliability indexes.

Description

Technical Field

[0001] The present application relates to the technical field of reliability design, and in particular to a system reliability allocation method and device. Background Art

[0002] System reliability allocation is the process of allocating the specified system reliability index to each component according to the given criteria. Traditional system reliability allocation methods include equal allocation method, scoring allocation method, proportional combination method and other allocation methods. These methods allocate reliability by calculating the component reliability combination that meets the system reliability allocation target. However, these allocation methods do not consider the variation range of system reliability under this combination, nor do they fully refer to the component importance information provided in the reliability analysis process.

[0003] During the development or operation phase, due to various reasons, the actual reliability of a component that can be achieved will definitely deviate slightly from the component reliability evaluated during the design phase, especially if it is lower than the lower limit of the component reliability evaluated during the design phase. In this case, the system reliability may no longer meet the specified system reliability index. At this time, even if a certain engineering margin has been reserved for the target reliability of the system reliability allocation, if the fluctuation of the system reliability with the change of the component reliability is large, but the system reliability still no longer meets the specified system reliability index, the system reliability allocation plan needs to be readjusted, and the risk of adjusting the reliability at this time is high.

[0004] Therefore, this application takes the system reliability change range as an important evaluation indicator, and comprehensively considers the component importance ranking to improve and perfect the system reliability allocation method. Summary of the invention

[0005] In view of the problem that the system reliability allocation scheme in the prior art has large volatility, the present application mainly provides a system reliability allocation method and device.

[0006] In order to achieve the above-mentioned purpose, the first technical solution adopted in the present application is: a system reliability allocation method, which includes: obtaining a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram; performing fault tree analysis based on the reliability block diagram and the mathematical model to calculate the probability expression of the top event of the system; using the probability expression of the top event, by calculating the partial differential of the probability of the top event with respect to the failure rate of each component, obtaining the probability importance expression of the component, and using the probability importance expression of the component, calculating the structural importance of the component; using the probability importance expression of the component to perform variable substitution, obtain the partial differential of the reliability of the system with respect to the reliability of each component, and using the partial differential of the reliability of each component to calculate the system reliability change gradient expression; determining the reliability allocation target reliability and target reliability accuracy of the system; calculating the first optimization constraint condition based on the reliability allocation target reliability and target reliability accuracy of the system, and calculating the second optimization constraint condition based on the structural importance of the component; calculating the optimization target of the system based on the system reliability change gradient expression; and performing target optimization iterative calculation based on the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain the reliability allocation result of the system.

[0007] Optionally, a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram are obtained, including: determining the reliability block diagram based on the system architecture, system functional requirements, component functions and connection relationships between components; and, based on the reliability block diagram, obtaining the mathematical model corresponding to the reliability block diagram by utilizing reliability modeling processing.

[0008] Optionally, a fault tree analysis is performed based on the reliability block diagram and the mathematical model to calculate a probability expression for the occurrence of the top event of the system, including: performing a fault tree analysis based on the reliability block diagram and the mathematical model to analyze the logical relationship between component failure events that lead to the occurrence of the top event; calculating the minimum cut set that leads to the occurrence of the top event based on the logical relationship; and, based on the minimum cut set for the occurrence of the top event, using non-overlapping decomposition processing to calculate a logical expression for the occurrence of the top event, and calculating an expression for the probability of the top event based on the logical expression.

[0009] Optionally, target optimization iterative calculation is performed according to the first optimization constraint, the second optimization constraint and the optimization target to obtain a reliability allocation result of the system, including: constructing a target optimization model of the optimization target according to the first optimization constraint, the second optimization constraint and the optimization target; performing target optimization iterative calculation on the target optimization model to obtain a target optimization iterative calculation result; and, reviewing the target optimization iterative calculation result to obtain a system reliability allocation result based on component importance and reliability change gradient.

[0010] Optionally, the logical expression for the top event is:

[0011]

[0012] Among them, C1, C2, …, C r is the minimum cut set that causes the top event to occur, X i It is a logical variable that describes the failure of each component in the system architecture. T is the logical expression of the top event occurrence;

[0013] The expression of the probability of the top event is: Q = P (T) = Q (q1, q2, ..., q n ), where q i is the failure probability of each component, and Q is the function of the failure probability of each component.

[0014] Optionally, the probability importance expression of the component is used to replace the variable, and the partial differential of the reliability of the system to the reliability of each component is obtained, and the partial differential of the reliability of each component is used to calculate the gradient expression of the system reliability change, including: the reliability of the system is R = 1-Q, the reliability of the component is r i =1-q i , then the probability importance expression of the component is used to replace the variable, and the calculated partial differential of the reliability of the system to the reliability of each component is And the gradient expression of system reliability change is obtained by using the partial differential calculation of each component reliability:

[0015]

[0016] Optionally, constructing a target optimization model of the optimization target according to the first optimization constraint, the second optimization constraint and the optimization target includes: an expression of the target optimization model of the optimization target constructed according to the first optimization constraint, the second optimization constraint and the optimization target is:

[0017]

[0018] Where R = R(r1, r2, …, r n )=1-Q(1-r1,1-r2,…,1-r n ), the reliability ranges of each component are

[0019] Optionally, determine the target reliability and target reliability accuracy of the reliability allocation of the system, including: determining the value range of the reliability of each component based on the failure mode and effect analysis results, or in combination with the actual component selection, so as to determine the target reliability of the reliability allocation of the system; and determine the target reliability accuracy by verifying the rationality of the setting of the target reliability of the reliability allocation of the system.

[0020] The second technical solution adopted in the present application is: a system reliability allocation device, which includes: an information acquisition module, which is used to obtain a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram; a probability expression acquisition module, which is used to perform fault tree analysis based on the reliability block diagram and the mathematical model, and calculate the probability expression of the top event of the system; a structural importance acquisition module, which is used to use the probability expression of the top event to obtain the probability importance expression of the component by calculating the partial differential of the failure rate of each component with respect to the probability of the top event, and use the probability importance expression of the component to calculate the structural importance of the component; a system reliability change gradient expression acquisition module, which is used to use the probability importance expression of the component to perform variable substitution to obtain The reliability of the system is obtained by calculating the partial differential of the reliability of each component, and the partial differential of the reliability of each component is used to calculate the system reliability change gradient expression; a reliability information acquisition module is used to determine the system reliability allocation target reliability and target reliability accuracy; a constraint condition acquisition module is used to calculate the first optimization constraint condition according to the system reliability allocation target reliability and target reliability accuracy, and calculate the second optimization constraint condition according to the structural importance of the component; an optimization target determination module is used to calculate the system optimization target according to the system reliability change gradient expression; and an allocation result acquisition module is used to perform target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain the system reliability allocation result.

[0021] Optionally, a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram are obtained, including: determining the reliability block diagram based on the system architecture, system functional requirements, component functions and connection relationships between components; and, based on the reliability block diagram, obtaining the mathematical model corresponding to the reliability block diagram by utilizing reliability modeling processing.

[0022] Optionally, a fault tree analysis is performed based on the reliability block diagram and the mathematical model to calculate a probability expression for the occurrence of the top event of the system, including: performing a fault tree analysis based on the reliability block diagram and the mathematical model to analyze the logical relationship between component failure events that lead to the occurrence of the top event; calculating the minimum cut set that leads to the occurrence of the top event based on the logical relationship; and, based on the minimum cut set for the occurrence of the top event, using non-overlapping decomposition processing to calculate a logical expression for the occurrence of the top event, and calculating an expression for the probability of the top event based on the logical expression.

[0023] Optionally, target optimization iterative calculation is performed according to the first optimization constraint, the second optimization constraint and the optimization target to obtain a reliability allocation result of the system, including: constructing a target optimization model of the optimization target according to the first optimization constraint, the second optimization constraint and the optimization target; performing target optimization iterative calculation on the target optimization model to obtain a target optimization iterative calculation result; and, reviewing the target optimization iterative calculation result to obtain a system reliability allocation result based on component importance and reliability change gradient.

[0024] Optionally, the logical expression for the top event is:

[0025]

[0026] Among them, C1, C2, …, C r is the minimum cut set that causes the top event to occur, X i It is a logical variable that describes the failure of each component in the system architecture. T is the logical expression of the top event occurrence;

[0027] The expression of the probability of the top event is: Q = P (T) = Q (q1, q2, ..., q n ), where q i is the failure probability of each component, and Q is the function of the failure probability of each component.

[0028] Optionally, the probability importance expression of the component is used to replace the variable, and the partial differential of the reliability of the system to the reliability of each component is obtained, and the partial differential of the reliability of each component is used to calculate the gradient expression of the system reliability change, including: the reliability of the system is R = 1-Q, the reliability of the component is r i =1-q i , then the probability importance expression of the component is used to replace the variable, and the calculated partial differential of the reliability of the system to the reliability of each component is And the gradient expression of system reliability change is obtained by using the partial differential calculation of each component reliability:

[0029]

[0030] Optionally, constructing a target optimization model of the optimization target according to the first optimization constraint, the second optimization constraint and the optimization target includes: an expression of the target optimization model of the optimization target constructed according to the first optimization constraint, the second optimization constraint and the optimization target is:

[0031]

[0032] Where R = R(r1, r2, …, r n )=1-Q(1-r1,1-r2,…,1-rn ), the reliability ranges of each component are

[0033] Optionally, determine the target reliability and target reliability accuracy of the reliability allocation of the system, including: determining the value range of the reliability of each component based on the failure mode and effect analysis results, or in combination with the actual component selection, so as to determine the target reliability of the reliability allocation of the system; and determine the target reliability accuracy by verifying the rationality of the setting of the target reliability of the reliability allocation of the system.

[0034] The beneficial effects that the technical solution of the present application can achieve are: reliability allocation based on component importance and reliability change gradient, making full use of component importance information such as structural importance and probability importance of components, and performing system reliability allocation, making the allocation scheme more practical and robust; and the system reliability allocation result provided by the present application can minimize the fluctuation amplitude of the system reliability corresponding to the component that meets the target reliability as the component reliability changes. By realizing this feature, if a component in the development stage or operation stage has a slight deviation from the component reliability evaluated in the design stage due to various reasons, especially when it is lower than the lower limit of the component reliability evaluated in the design stage, the system reliability of the present application has the smallest fluctuation amplitude as the component reliability changes. At the same time, the present application takes into account that the structural importance of the component is independent of the reliability value of each component, so the present application adopts the structural importance as the basis for system reliability allocation, which can maintain the consistency of the component reliability constraint relationship and meet the compliance of the component reliability with the component importance; finally, the system reliability achieved by the system reliability allocation result provided by the present application can strictly control the system reliability within the accuracy range of the target reliability, avoid allocating too high reliability indicators, and introduce unnecessary development costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 It is a schematic diagram of a specific implementation of a system reliability allocation method of the present application;

[0037] Figure 2 1 is a schematic diagram of the main process of system reliability allocation in the present application;

[0038] Figure 3 is a reliability block diagram of an embodiment provided by the present application;

[0039] Figure 4 is a fault tree corresponding to the reliability block diagram of the embodiment provided by the present application;

[0040] Figure 5 It is a schematic diagram of a specific implementation of a system reliability allocation device of the present application.

[0041] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] The preferred embodiments of the present application are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present application can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present application.

[0043] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "comprising" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprising..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0044] Definition: Reliability refers to the ability of a system to complete specified functions within a specified time and under specified conditions. The probability measurement that characterizes the reliability of the system is called reliability.

[0045] The reliability block diagram is a graphical representation of system reliability. It describes the logical relationship between components when the system is running and is the preferred analysis method when conducting reliability analysis.

[0046] The reliability model is a description of the reliability logical relationship between the various components in the system and its architecture, which includes the reliability block diagram and the corresponding mathematical model.

[0047] Reliability modeling is the process of drawing a reliability block diagram based on system architecture and functional requirements and establishing a mathematical model corresponding to the reliability block diagram.

[0048] Fault tree is a special tree-like logical causal relationship diagram, which describes the causal relationship between various events in the system by using event symbols, logic gate symbols and transfer symbols. And the fault tree analysis takes the undesirable system failure event (i.e., the top event) as the analysis target, and strictly carries out causal logic analysis layer by layer from top to bottom, analyzing all the causes and cause combinations that lead to the top event, and calculating quantitative indicators such as the probability of occurrence of the top event and the importance of the bottom event based on the basic data.

[0049] A cut set is a collection of several bottom events of a fault tree, and when all these bottom events occur, the top event will occur. Among them, the minimum cut set is a cut set in which the number of bottom events cannot be reduced any further, that is, after removing any bottom event from the minimum cut set, the remaining set of bottom events is no longer a cut set. The minimum cut set represents a fault mode that causes the top event of the fault tree to occur.

[0050] System reliability allocation is the process of allocating the specified system reliability indicators to each component according to given criteria.

[0051] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The specific embodiments described below can be combined with each other to form new embodiments. The same or similar ideas or processes described in one embodiment may not be repeated in other embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0052] Figure 1 An implementation of a system reliability allocation method of the present application is shown.

[0053] Figure 1 The system reliability allocation method shown includes: step S101, obtaining a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram;

[0054] Step S102, performing fault tree analysis based on the reliability block diagram and mathematical model, and calculating the probability expression of the top event of the system;

[0055] Step S103, using the probability expression of the top event occurrence, by calculating the partial differential of the top event occurrence probability with respect to the failure rate of each component, the probability importance expression of the component is obtained, and using the probability importance expression of the component, the structural importance of the component is calculated;

[0056] Step S104, using the probability importance expression of the component to perform variable substitution, obtain the partial differential of the system reliability to the reliability of each component, and use the partial differential of the reliability of each component to calculate the system reliability change gradient expression;

[0057] Step S105, determining the reliability allocation target reliability and target reliability accuracy of the system;

[0058] Step S106, calculating the first optimization constraint condition according to the reliability distribution target reliability and the target reliability accuracy of the system, and calculating the second optimization constraint condition according to the structural importance of the component;

[0059] Step S107, calculating the optimization target of the system according to the system reliability change gradient expression; and,

[0060] Step S108, performing target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain a reliability allocation result of the system.

[0061] This specific implementation method allocates reliability based on the system reliability of component importance and reliability change gradient, makes full use of component importance information such as structural importance and probability importance of components, and allocates system reliability, making the allocation result more reliable; and the system reliability allocation result provided by this application can minimize the fluctuation of the system reliability corresponding to the component of the target reliability as the reliability of the component changes. By realizing this feature, if a component in the development stage or operation stage has a slight deviation from the component reliability evaluated in the design stage due to various reasons, especially when it is lower than the lower limit of the component reliability evaluated in the design stage, the system reliability of this application will minimize the fluctuation of the component reliability as the component reliability changes. At the same time, this application takes into account that the structural importance of the component is independent of the reliability value of each component, so this application uses structural importance as the basis for system reliability allocation, which can maintain the consistency of the component reliability constraint relationship and meet the compliance of component reliability and component importance; finally, the system reliability achieved by the system reliability allocation result provided by this application can strictly control the system reliability within the accuracy range of the target reliability, avoid allocating too high reliability indicators, and introduce unnecessary development costs.

[0062] Specifically, engineering practice shows that when examining system design from the perspective of reliability, each component in the system architecture is not equally important. It is necessary to introduce the concept of importance to measure the impact of a component on system reliability. The structural importance and probability importance of components quantify the impact of each component failure on the occurrence of top events from the perspectives of system architecture and component reliability changes, respectively. They are important concepts in fault tree analysis, which are very valuable for improving system design.

[0063] Based on this, after carrying out reliability modeling and analysis, this application makes full use of component importance information such as structural importance and probability importance of components according to the fault tree analysis results to allocate system reliability.

[0064] Figure 2 FIG. 2 is a schematic diagram of the main process of system reliability allocation in this application. Figure 2 As shown in the figure, before carrying out the system reliability allocation, it is necessary to first clarify the system architecture, the system functional requirements, the component functions and the connection relationship between the components. Then, using reliability modeling, a reliability block diagram is drawn based on the system architecture and functional requirements, and a mathematical model corresponding to the reliability block diagram is established. Based on the system reliability block diagram and the mathematical model corresponding to the reliability block diagram, a fault tree analysis is carried out to analyze the logical relationship between the component failure events that lead to the top event, and the minimum cut set that leads to the top event is calculated. Then, based on the minimum cut set of the top event, a non-intersecting decomposition is performed to calculate the logical expression of the top event, and then the expression of the probability of the top event is calculated based on the logical expression of the top event. Then, based on the expression of the probability of the top event, the partial differential of the probability of the top event with respect to the failure rate of each component is calculated to obtain the expression of the probability importance of each component. Then, based on the expression of the probability importance, the structural importance of each component is calculated. And, according to the expression of the probability importance, variable substitution is performed to obtain the partial differential of the system reliability with respect to the reliability of each component, and based on the partial differential of the system reliability with respect to the reliability of each component, the expression of the gradient of the system reliability change is obtained. Afterwards, in the working process, the designer proposes the reliability target according to the complexity of the system intuitively reflected by the reliability block diagram, determines the target reliability of the system reliability allocation, and the target reliability accuracy, so as to avoid blind determination of unrealistic reliability allocation. Then, according to the system reliability allocation target reliability and target reliability accuracy, structural importance and system reliability change gradient expression, they are transformed into the optimization target and constraint conditions of the constructed target optimization model one by one. Finally, the target optimization model constructed by the optimization target and constraint conditions is used to perform the target optimization iteration calculation to obtain the corresponding reliability allocation scheme and the reliability value corresponding to the scheme. The reliability allocation result is reviewed by checking whether the reliability value is greater than the target reliability determined above, and whether the difference between the current reliability value and the reliability value of the previous round of optimization results is not greater than the target reliability accuracy. When the current reliability value is greater than the target reliability, and the difference between the reliability value of the current iteration result and the reliability value of the previous round of optimization results is less than the target reliability accuracy, that is, when the space for further optimization of the current allocation scheme is less than the predetermined value, the current optimization result at this time is used as the system reliability allocation result based on component importance and reliability change gradient.

[0065] exist Figure 1 In the illustrated implementation, the system reliability allocation method includes step S101 of acquiring a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram.

[0066] In a specific embodiment of the present application, a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram are obtained, including: determining the reliability block diagram according to the system architecture, system functional requirements, component functions and connection relationships between components; and, based on the reliability block diagram, using reliability modeling processing to obtain the mathematical model corresponding to the reliability block diagram.

[0067] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S102, performing a fault tree analysis based on a reliability block diagram and a mathematical model to calculate a probability expression of the occurrence of a top event of the system.

[0068] In a specific embodiment of the present application, a fault tree analysis is performed based on a reliability block diagram and a mathematical model to calculate a probability expression for the occurrence of a top event of the system, including: performing a fault tree analysis based on the reliability block diagram and the mathematical model to analyze the logical relationship between component failure events that lead to the occurrence of the top event; calculating the minimum cut set that leads to the occurrence of the top event based on the logical relationship; and, based on the minimum cut set for the occurrence of the top event, using non-intersecting decomposition processing to calculate a logical expression for the occurrence of the top event, and calculating an expression for the probability of the occurrence of the top event based on the logical expression.

[0069] Specifically, the fault tree analysis is carried out according to the reliability block diagram and its corresponding mathematical model, the logical relationship between the component failure events that lead to the top event is analyzed, and the minimum cut set that leads to the top event is calculated. Based on the minimum cut set of the top event, the non-intersecting decomposition is performed to calculate the logical expression of the top event, and then the expression of the probability of the top event is calculated. If X is assumed i are logical variables that describe the failure of each component in the system architecture, and C1, C2, …, C r is the minimum cut set of all fault trees. When the probability of occurrence of the top event is calculated using the non-intersection method, the expression of the cut set event is:

[0070]

[0071] At this time, the logical expression of the top event is:

[0072]

[0073] Among them, C1, C2, …, C r is the minimum cut set that causes the top event to occur, X i It is a logical variable that describes the failure of each component in the system architecture. T is the logical expression of the top event occurrence;

[0074] Therefore, the expression of the probability of the top event is: Q = P (T) = Q (q1, q2, ..., q n ), where qi is the failure probability of each component, and Q is the function of the failure probability of each component.

[0075] That is, let K i =X1X2…X l , then

[0076]

[0077] Then the logical expression of the top event is

[0078]

[0079] Assume that the failure probability of each component is q i , then the probability of the top event is a function of the failure probability of each component and can be written as Q = P (T) = Q (q1, q2, ..., q n ), Q is the function of the failure probability of each component.

[0080] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S103, using the probability expression of the top event occurrence, obtaining the probability importance expression of the component by calculating the partial differential of the probability of the top event occurrence with respect to the failure rate of each component, and using the probability importance expression of the component to calculate the structural importance of the component.

[0081] In a specific embodiment of the present application, the probability importance expression of the component is used to perform variable substitution to obtain the partial differential of the reliability of the system to the reliability of each component, and the partial differential of the reliability of each component is used to calculate the system reliability change gradient expression, including: the reliability of the system is R = 1-Q, the reliability of the component is r i =1-q i , then the probability importance expression of the component is used to replace the variable, and the calculated partial differential of the reliability of the system to the reliability of each component is as well as

[0082] The gradient expression of system reliability change is obtained by using the partial differential calculation of each component reliability:

[0083]

[0084] Specifically, the partial differential of the top event occurrence probability with respect to the failure rate of each component is calculated, and the probability importance expression of each component is obtained as follows:

[0085]

[0086] Using the probability importance expression calculated using the probability importance of the above components, the structural importance of each component is:

[0087] I Φ (X i )=I P (X i )| 当所有q =0.5

[0088] Then, the structural importance of each component is sorted according to its structural importance. For example, let (s1, s2, …, s n ) is a sequence of components sorted from small to large according to structural importance, and s i is the identifier of the component, then the components are sorted according to their structural importance as follows:

[0089] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S104, using the probability importance expression of the component to perform variable substitution to obtain the partial differential of the system reliability to the reliability of each component, and using the partial differential of the reliability of each component to calculate the system reliability change gradient expression.

[0090] Specifically, the probability importance expression is replaced by variables to obtain the partial differential of system reliability to each component reliability, that is, let system reliability R = 1-Q, component reliability r i =1-q i , then the partial differential of system reliability to the reliability of each component can be expressed as

[0091] By partial differentiation of system reliability with respect to the reliability of each component, the expression of system reliability gradient change is calculated as:

[0092]

[0093] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S105, determining a reliability allocation target reliability and a target reliability accuracy of the system.

[0094] In a specific embodiment of the present application, the target reliability and target reliability accuracy of the reliability allocation of the system are determined, including: determining the value range of the reliability of each component based on the failure mode and effect analysis results, or in combination with the actual component selection, so as to determine the target reliability of the reliability allocation of the system; and determining the target reliability accuracy by verifying the rationality of the setting of the target reliability of the system reliability allocation.

[0095] Specifically, for example, based on the results of the failure mode and effect analysis, or in combination with the actual component selection, that is, the component reliability value in the selected product manual, the value range of each component reliability is clarified, and the rationality of the system reliability allocation target reliability setting is verified. If each component takes the maximum value and still cannot meet the system reliability allocation target, the system reliability allocation target reliability should be readjusted, or the value range of each component reliability should be re-evaluated.

[0096] Assume that the target reliability of system reliability allocation is R T , the target reliability accuracy is △R T =(1-R T )·c, where c is the proportionality coefficient and c<<1. Then the dynamic range of the system reliability allocation result meets R T ≤R≤R T +△R T .

[0097] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S106, calculating a first optimization constraint condition according to the system reliability allocation target reliability and target reliability accuracy, and calculating a second optimization constraint condition according to the structural importance of the component.

[0098] exist Figure 1 In the illustrated embodiment, the system reliability allocation method includes step S107, calculating and obtaining the optimization target of the system according to the system reliability change gradient expression.

[0099] Among them, the optimization goal is to minimize the gradient of system reliability change, and the constraint target is the value range of system reliability (determined by the target reliability and target reliability accuracy of system reliability allocation) and the component reliability constraint sorted according to structural importance (that is, the higher the structural importance of the component, the higher the reliability should be allocated).

[0100] exist Figure 1 In the illustrated implementation, the system reliability allocation method includes step S108, performing target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain a system reliability allocation result.

[0101] In a specific embodiment of the present application, a target optimization model of the optimization target is constructed according to the first optimization constraint, the second optimization constraint and the optimization target; the target optimization iterative calculation is performed on the target optimization model to obtain the target optimization iterative calculation result; and the target optimization iterative calculation result is reviewed to obtain the system reliability allocation result based on the component importance and the reliability change gradient.

[0102] In a specific embodiment of the present application, the expression of the target optimization model of the optimization target constructed according to the first optimization constraint condition, the second optimization constraint condition and the optimization target is:

[0103]

[0104] Where R = R(r1, r2, …, r n )=1-Q(1-r1,1-r2,…,1-r n ), the reliability ranges of each component are

[0105] In a specific embodiment of the present application, the system reliability allocation result is reviewed by judging whether the system reliability is greater than the target reliability; whether the system reliability accuracy is less than the target reliability accuracy; whether the reliability allocated to each component is within the constrained interval; and whether the ranking of the reliability allocated to each component complies with the reliability importance ranking constraint.

[0106] Specifically, the system reliability allocation target reliability and target reliability accuracy, structural importance and system reliability change gradient expressions are converted into optimization objectives and constraints one by one to obtain the target optimization model shown below, and the target optimization iterative calculation is performed.

[0107]

[0108] Where R = R(r1, r2, ..., r n )=1-Q(1-r1,1-r2,…,1-r n ), the reliability ranges of each component are

[0109] The target optimization iterative calculation results are reviewed and the system reliability allocation results based on component importance and reliability change gradient are determined. i}, where i = 1, 2,…, n.

[0110] In a specific embodiment of the present application, Figure 3 The system architecture shown is used as the object of system reliability allocation, and the calculation process of system reliability allocation based on component importance and reliability change gradient is explained, as well as the applicability of the proposed method.

[0111] Before allocating the reliability of the system, it is necessary to first clarify the system architecture, system functional requirements, component functions, and the connection relationship between components. Based on the above-determined system architecture and functions, a reliability block diagram of the system is drawn, and reliability modeling is carried out based on the reliability block diagram, so as to establish a mathematical model corresponding to the reliability block diagram. The reliability block diagram and its corresponding mathematical model are different forms of describing the system architecture, in which the reliability block diagram is a more intuitive block diagram, and the corresponding mathematical model is a rational mathematical description.

[0112] Figure 3 is a reliability block diagram of an embodiment provided by the present application. Figure 3 Taking the system reliability block diagram shown in the figure as an example, components A and B form parallel working redundancy and are connected in series with component C. In practical applications, the reliability block diagram used for system reliability modeling is usually a more complex block diagram composed of a series structure and a parallel structure. That is to say, not all system reliability block diagrams can be simplified to a combination of a series or parallel structure. Figure 2 Component D is a redundant component of the parallel structure of components A and B. It forms a set of working redundancy for system operation with component C, and forms another set of working redundancy for system operation with component E.

[0113] according to Figure 3 The system architecture and its corresponding mathematical model shown in the figure are used to conduct a fault tree analysis on the system, analyze the logical relationship between the component failure events that lead to the top event, and calculate the minimum cut set that leads to the top event. Then, based on the minimum cut set of the top event, a non-overlapping decomposition is performed to calculate the logical expression of the top event, and then the expression of the probability of the top event is calculated based on the logical expression.

[0114] For example, through fault tree analysis, we know that if component C and component D fail at the same time, component C and component E fail at the same time, and component A, component B, and component D fail at the same time, the system will not be able to operate normally. i When the logical variables are used to describe the failure of each component in the system architecture, the minimum cut set of the fault tree is {X C ,X D}、{X C ,X E} and {X A ,X B ,X D}.

[0115] The above minimum cut set is used to calculate the probability of occurrence of the top event using the non-intersection method, and then there is a cut set event K1 = X C X D 、K2=X C X E 、K3=X AX B X D ,at this time

[0116] The logical expression of the top event is:

[0117]

[0118] If the failure probabilities of component A, component B, component C, component D, and component E are q A ,q B ,q C ,q D and q E , then the probability of the top event occurring is:

[0119]

[0120] According to the expression of the probability of occurrence of the top event, the partial differential of the probability of occurrence of the top event with respect to the failure rate of each component is calculated, and the expressions of the probability importance of each component are obtained as follows:

[0121]

[0122] Then, according to the probability importance expression obtained by the above calculation, the structural importance of each component is calculated, where the calculation process of the structural importance of component A is: Φ (X A )=I P (X A )| 当所有q＝0.5 =0.5×(1-0.5)×0.5=0.125. Similarly, the structural importance of other components can be obtained as I Φ (X B )=0.125、I Φ (X C )=0.625、I Φ (X D )=0.375、I Φ (X E )=0.25.

[0123] Then, the probability importance expression of the component is used to replace the variables to obtain the partial differential of the system reliability to the reliability of each component, and the partial differential of the reliability of each component is used to calculate the gradient expression of the system reliability change.

[0124] The calculation process is to set the system reliability R = 1-Q and the component reliability r i =1-q i , after replacing the variables using the probability importance expression of the components, the partial differential of the system reliability to the reliability of each component can be expressed as:

[0125]

[0126] According to the partial differential of the system reliability calculated above with respect to the reliability of each component, the expression of the system reliability change gradient calculated is:

[0127]

[0128] Then, determine the target reliability of the system reliability allocation and the target reliability accuracy, that is, based on the failure mode and effect analysis results, or combined with the actual component selection, clarify the value range of each component reliability, that is, the target reliability, and verify the rationality of the system reliability allocation target reliability setting, so as to obtain the target reliability accuracy. For example, when each component takes the maximum value, it still cannot meet the system reliability allocation target, then the system reliability allocation target reliability should be readjusted, or the value range of each component reliability should be re-evaluated. In this embodiment, the target reliability of the system reliability allocation is set to R T =0.999999; then the target reliability accuracy of system reliability allocation is △R T =(1-R T )·c, usually the coefficient is c=0.001, so the dynamic range of the system reliability allocation result conforms to R T ≤R≤R T +△R T .

[0129] According to the above determined system reliability allocation target reliability and target reliability accuracy, they are transformed into the first constraint condition for the system reliability allocation result calculation process. Then the dynamic range of the system reliability allocation result meets R T ≤R≤R T +△R T , which can be decomposed into two constraint inequalities R T -R≤0 and R-(R T +△R T )≤0.

[0130] According to the calculated structural importance of the components, referring to the system reliability allocation principle proposed in GB / T 36245 "Guidelines for Reliability Allocation of Industrial Process Measurement and Control Instruments", "higher reliability index should be allocated to the parts with high critical importance", it is converted into the second constraint condition for the calculation process of system reliability allocation results. Figure 3 The structural importance of each component in is I Φ (A)=I Φ (B) Φ (E) Φ (D) Φ ​​​(C), so the system reliability allocation result should meet r A =r B ≤r E ≤r D ≤r C . Among them, the functions and impacts of component A and component B in the system architecture are exactly the same. If there is no special reason, you can use r A =r B =r A' , then there is a second constraint r A' ≤r E ≤r D ≤r C It should be pointed out that other system reliability allocation principles involving indicators such as component complexity, technology maturity, and maintainability, if supported by relevant data, can also refer to the above method and be included in the scope of system reliability allocation as constraints.

[0131] According to the gradient expression of system reliability change, the optimization target that needs to be optimized in the system is calculated. By substituting the partial differential expression of system reliability to component reliability, the expression of the system optimization target can be obtained as follows:

[0132]

[0133] According to the above constraint equations and optimization objectives, it can be known that the target optimization model of the system is:

[0134]

[0135] Where R = R(r A' ,r C ,r D ,r E )=1-Q(1-r A' ,1-r A' ,1-r C ,1-r D ,1-r E ), and the reliability ranges of each component are

[0136] According to the target optimization model constructed above, the target optimization iterative calculation is performed, and the result of system reliability distribution is obtained as r A =r B =0.99273599, r C =0.99940309, r D =0.99932611, r E =0.99905777. At this time, the system reliability reaches R=0.9999990001636768, meeting the system reliability allocation target requirements.

[0137] It should be pointed out that other single-objective optimization algorithms and multi-objective optimization algorithms are applicable to the target optimization iterative calculation in this embodiment.

[0138] Figure 5 A specific implementation of a system reliability allocation device of the present application is shown.

[0139] exist Figure 5 In the specific implementation manner shown, the system reliability allocation device mainly includes: an information acquisition module, which is used to acquire a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram; a probability expression acquisition module, which is used to perform fault tree analysis based on the reliability block diagram and the mathematical model, and calculate the probability expression of the top event of the system; a structural importance acquisition module, which is used to use the probability expression of the top event to obtain the probability importance expression of the component by calculating the partial differential of the failure rate of each component with respect to the probability of the top event, and use the probability importance expression of the component to calculate the structural importance of the component; a system reliability change gradient expression acquisition module, which is used to use the probability importance expression of the component to perform variable substitution and obtain the system The reliability of the system is calculated by the partial differential of the reliability of each component, and the partial differential of the reliability of each component is used to calculate the system reliability change gradient expression; a reliability information acquisition module is used to determine the reliability allocation target reliability and target reliability accuracy of the system; a constraint condition acquisition module is used to calculate the first optimization constraint condition according to the reliability allocation target reliability and target reliability accuracy of the system, and calculate the second optimization constraint condition according to the structural importance of the component; an optimization target determination module is used to calculate the optimization target of the system according to the system reliability change gradient expression; and an allocation result acquisition module is used to perform target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain the reliability allocation result of the system.

[0140] In a specific embodiment of the present application, a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram are obtained, including: determining the reliability block diagram according to the system architecture, system functional requirements, component functions and connection relationships between components; and, based on the reliability block diagram, using reliability modeling processing to obtain the mathematical model corresponding to the reliability block diagram.

[0141] In a specific embodiment of the present application, a fault tree analysis is performed based on a reliability block diagram and a mathematical model to calculate a probability expression for the occurrence of a top event of the system, including: performing a fault tree analysis based on the reliability block diagram and the mathematical model to analyze the logical relationship between component failure events that lead to the occurrence of the top event; calculating the minimum cut set that leads to the occurrence of the top event based on the logical relationship; and, based on the minimum cut set for the occurrence of the top event, using non-intersecting decomposition processing to calculate a logical expression for the occurrence of the top event, and calculating an expression for the probability of the occurrence of the top event based on the logical expression.

[0142] In a specific embodiment of the present application, target optimization iterative calculation is performed according to the first optimization constraint, the second optimization constraint and the optimization target to obtain a reliability allocation result of the system, including: constructing a target optimization model of the optimization target according to the first optimization constraint, the second optimization constraint and the optimization target; performing target optimization iterative calculation on the target optimization model to obtain a target optimization iterative calculation result; and, reviewing the target optimization iterative calculation result to obtain a system reliability allocation result based on component importance and reliability change gradient.

[0143] In a specific embodiment of the present application, the logical expression for the occurrence of the top event is:

[0144]

[0145] Among them, C1, C2, …, C r is the minimum cut set that causes the top event to occur, X i It is a logical variable that describes the failure of each component in the system architecture. T is the logical expression of the top event occurrence;

[0146] The expression of the probability of the top event is: Q = P (T) = Q (q1, q2, ..., q n ), where q i is the failure probability of each component, and Q is the function of the failure probability of each component.

[0147] In a specific embodiment of the present application, the probability importance expression of the component is used to perform variable substitution to obtain the partial differential of the reliability of the system to the reliability of each component, and the partial differential of the reliability of each component is used to calculate the system reliability change gradient expression, including: the reliability of the system is R = 1-Q, the reliability of the component is r i =1-q i , then the probability importance expression of the component is used to replace the variable, and the calculated partial differential of the reliability of the system to the reliability of each component is as well as

[0148] The gradient expression of system reliability change is obtained by using the partial differential calculation of each component reliability:

[0149]

[0150] In a specific embodiment of the present application, the expression of the target optimization model of the optimization target constructed according to the first optimization constraint condition, the second optimization constraint condition and the optimization target is:

[0151]

[0152] Where R = R(r1, r2, …, r n )=1-Q(1-r1,1-r2,…,1-r n ), the reliability ranges of each component are

[0153] The system reliability allocation device provided in the present application can be used to execute the system reliability allocation method based on component importance and reliability change gradient described in any of the above embodiments. Its implementation principle and technical effects are similar and will not be repeated here.

[0154] In a specific embodiment of the present application, each functional module in a system reliability allocation device proposed in the present application can be executed directly in hardware, in a software module executed by a processor, or in a combination of the two.

[0155] The software modules may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from and write information to the storage medium.

[0156] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), or other programmable logic devices, discrete gates or transistor logic, discrete hardware components, or any combination thereof. A general-purpose processor may be a microprocessor, but in an alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration. In an alternative, the storage medium may be integrated with the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In an alternative, the processor and the storage medium may reside in a user terminal as discrete components.

[0157] In another specific embodiment of the present application, a computer-readable storage medium stores a computer program / instruction, and the computer program / instruction is operated to execute the system reliability allocation method described in the above embodiment.

[0158] In a specific embodiment of the present application, a computer device includes a memory, a processor, and a computer program stored in the memory, and the processor executes the computer program to implement the system reliability allocation method described in the above embodiment.

[0159] In a specific embodiment of the present application, a computer program product includes a computer program / instruction, and when the computer program / instruction is executed by a processor, the system reliability allocation method described in the above embodiment is implemented.

[0160] In the multiple embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0161] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0162] The above description is only an embodiment of the present application and does not limit the patent scope of the present application. Any equivalent structural transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A system reliability allocation method, characterized in that: include: Obtain the reliability block diagram that reflects the system architecture and functional requirements and the mathematical model corresponding to the reliability block diagram; Perform fault tree analysis based on the reliability block diagram and mathematical model to calculate the probability expression of the top event of the system; Using the probability expression of the top event occurrence, the probability importance expression of the component is obtained by calculating the partial differential of the probability of the top event occurrence with respect to the failure rate of each component, and using the probability importance expression of the component, the structural importance of the component is calculated; Using the probability importance expression of the component to perform variable substitution, the partial differential of the reliability of the system to the reliability of each component is obtained, and the partial differential of the reliability of each component is used to calculate the gradient expression of the system reliability change; Determine the reliability allocation target reliability and target reliability accuracy of the system; A first optimization constraint condition is calculated based on the reliability allocation target reliability of the system and the target reliability accuracy, and a second optimization constraint condition is calculated based on the structural importance of the component; According to the system reliability change gradient expression, the optimization target of the system is calculated; as well as, An iterative calculation of target optimization is performed according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain a reliability allocation result of the system.

2. The system reliability allocation method according to claim 1, characterized in that: The obtaining of a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram includes: Determine the reliability block diagram according to the system architecture, system function requirements, component functions and connection relationships between components; and, According to the reliability block diagram, a mathematical model corresponding to the reliability block diagram is obtained by using reliability modeling processing.

3. The system reliability allocation method according to claim 1, characterized in that: The fault tree analysis is performed according to the reliability block diagram and the mathematical model to calculate the probability expression of the top event of the system, including: Performing a fault tree analysis based on the reliability block diagram and mathematical model to analyze the logical relationship between component failure events that lead to the occurrence of the top event; Calculate the minimum cut set that causes the top event to occur according to the logical relationship; and According to the minimum cut set of the top event occurrence, a logical expression of the top event occurrence is calculated by using a disjoint decomposition process, and an expression of the probability of the top event occurrence is calculated according to the logical expression.

4. The system reliability allocation method according to claim 1, characterized in that: The performing target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain a reliability allocation result of the system includes: Constructing a target optimization model of the optimization target according to the first optimization constraint condition, the second optimization constraint condition and the optimization target; Performing target optimization iterative calculation on the target optimization model to obtain a target optimization iterative calculation result; and, The target optimization iterative calculation results are reviewed to obtain system reliability allocation results based on component importance and reliability change gradients.

5. The system reliability allocation method according to claim 3, characterized in that: The logical expression of the top event is: Among them, C1, C2, …, C r is the minimum cut set that causes the top event to occur, X i It is a logical variable that describes the failure of each component in the system architecture. T is the logical expression of the top event occurrence; The expression of the probability of the top event is: Q = P (T) = Q (q1, q2, ..., q n ), where q i is the failure probability of each component, and Q is the function of the failure probability of each component.

6. The system reliability allocation method according to claim 1, characterized in that: The probability importance expression of the component is used to perform variable substitution to obtain the partial differential of the reliability of the system to the reliability of each component, and the partial differential of the reliability of each component is used to calculate the gradient expression of the system reliability change, including: The reliability of the system is R = 1-Q, and the reliability of the component is r i =1-q i , then the probability importance expression of the component is used to replace the variables, and the partial differential of the reliability of the system to each component is calculated as as well as The gradient expression of system reliability change is obtained by using the partial differential calculation of each component reliability:

7. The system reliability allocation method according to claim 4, characterized in that: The step of constructing a target optimization model for the optimization target according to the first optimization constraint condition, the second optimization constraint condition and the optimization target includes: The expression of the target optimization model of the optimization target constructed according to the first optimization constraint condition, the second optimization constraint condition and the optimization target is: min s.t. Where R = R(r1, r2, …, r n )=1-Q(1-r1,1-r2,…,1-r n ), the reliability ranges of each component are 8. The system reliability allocation method according to claim 1, characterized in that: The step of determining the reliability allocation target reliability and target reliability accuracy of the system includes: According to the results of the failure mode and effect analysis, or in combination with the actual component selection, determine the value range of the reliability of each component, so as to determine the target reliability of the system reliability allocation; and The target reliability accuracy is determined by verifying the rationality of the target reliability setting of the system reliability allocation.

9. A system reliability allocation device, characterized in that: include: An information acquisition module is used to obtain a reliability block diagram reflecting the system architecture and functional requirements and a mathematical model corresponding to the reliability block diagram; A probability expression acquisition module is used to perform fault tree analysis based on the reliability block diagram and mathematical model, and calculate the probability expression of the top event of the system; A structural importance acquisition module is used to obtain a component's probability importance expression by using the probability expression of the top event occurrence, by calculating the partial differential of the top event occurrence probability with respect to the failure rate of each component, and to calculate the component's structural importance by using the component's probability importance expression; A system reliability change gradient expression acquisition module is used to perform variable substitution using the probability importance expression of the component to obtain the partial differential of the system reliability to the reliability of each component, and to calculate the system reliability change gradient expression using the partial differential of the reliability of each component; A reliability information acquisition module is used to determine the reliability allocation target reliability and target reliability accuracy of the system; A constraint condition acquisition module, used to calculate a first optimization constraint condition according to the reliability distribution target reliability of the system and the target reliability accuracy, and to calculate a second optimization constraint condition according to the structural importance of the component; An optimization target determination module calculates the optimization target of the system according to the system reliability change gradient expression; as well as, The allocation result acquisition module is used to perform target optimization iterative calculation according to the first optimization constraint condition, the second optimization constraint condition and the optimization target to obtain the reliability allocation result of the system.

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