Radar fault positioning method based on hierarchical fault tree modeling and probability analysis

Abstract

The invention relates to the technical field of radar equipment guarantee and intelligent maintenance, in particular to a radar fault positioning method based on hierarchical fault tree modeling and probability analysis. According to the method, the radar system is comprehensively analyzed, the top event is determined, the middle event and the bottom event are derived step by step, the radar fault tree is constructed, and after arrangement and optimization, fault diagnosis is achieved in combination with qualitative and quantitative analysis. The radar fault diagnosis method can help maintenance personnel to quickly position radar faults, improves diagnosis efficiency and accuracy, is especially suitable for radar equipment with a complex structure, and solves the problems of high difficulty and low efficiency of existing radar fault diagnosis.

Description

Technical Field

[0001] This invention relates to the field of radar equipment support and intelligent maintenance technology, and in particular to a radar fault location method based on hierarchical fault tree modeling and probabilistic analysis. Background Technology

[0002] With the rapid development of radar technology, new technologies, devices, and processes are widely used in the design and manufacturing of radar equipment, making the structure of new radars increasingly complex and the connections between various systems increasingly tight. This trend has led to significant challenges in fault diagnosis after a radar malfunction. Traditional fault diagnosis methods are unable to quickly and accurately locate the cause of the fault, which not only prolongs the radar's downtime for maintenance but may also affect the normal operation of the radar system and cause inconvenience to related fields.

[0003] Fault tree analysis (FBA), a method with significant advantages in fault diagnosis, can clearly identify the logical relationship between fault phenomena and their causes, making it particularly suitable for the repair of complex electronic equipment. However, the current application of FBA to radar fault diagnosis lacks a standardized and systematic implementation process. Numerous irregularities exist in the construction, optimization, and subsequent analysis of the fault tree, making it difficult to effectively guarantee the efficiency and accuracy of fault diagnosis. Therefore, a standardized radar fault diagnosis method based on hierarchical fault tree modeling and probabilistic analysis is urgently needed to meet the practical needs of radar maintenance work.

[0004] In summary, existing maintenance methods suffer from problems such as difficulty in diagnosing radar faults and low efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a radar fault diagnosis method based on hierarchical fault tree modeling and probabilistic analysis. This method involves a comprehensive analysis of the radar system to identify the top event, progressively deriving intermediate and bottom events to construct a radar fault tree. After refinement and optimization, fault diagnosis is achieved through a combination of qualitative and quantitative analysis. This invention helps maintenance personnel quickly locate radar faults, improving diagnostic efficiency and accuracy. It is particularly suitable for complex radar equipment, solving the problems of high difficulty and low efficiency in existing radar fault diagnosis methods.

[0006] The technical solution of this invention is: a radar fault location method based on hierarchical fault tree modeling and probabilistic analysis, characterized by the following steps:

[0007] Step 1: Determine the top event of the fault tree: The top event is the key issue of the research object, and the top event can be decomposed downwards;

[0008] Step 2: Determine boundary conditions, for a certain top event, reasonable analysis of the boundary conditions of fault tree, the boundary conditions of fault tree include: the working state of the components associated with the top event; in the process of fault tree establishment of events determined not allowed to occur; in the system operation process will inevitably occur and inevitably do not happen event;

[0009] Step 3: Analysis of the top event causes: should be analyzed the causes of the top event, that is, to find secondary events, in the top event failure cause analysis;

[0010] Step 4: Establish fault tree: build a top event as a starting point, step by step analysis of all potential causes leading to the top event, and then determine the intermediate events; for each intermediate event, the next level of decomposition, until the bottom event that triggers the intermediate event is found; through the logic symbol connection of all events, the fault tree model of the system is established;

[0011] Step 5: Fault tree qualitative analysis: analysis of the cut set and the minimal cut set of the system fault, determine the key factors of the fault, build the logical relationship between the top event and the bottom event;

[0012] Step 6: Fault tree quantitative analysis; analysis of the probability of each bottom event, according to the failure probability of each bottom event, through quantitative analysis to obtain the probability of the top event failure of the system, and then evaluate the importance of the bottom event to the top event;

[0013] Assume the bottom event The probability of failure is Since each bottom event is independent of each other, the probability of the minimal cut set is expressed as:

[0014]

[0015] In the formula, is the cut vector;

[0016] The minimal cut set is a set of single bottom event , the probability of the minimal cut set of the fault tree is expressed as:

[0017]

[0018] The probability of the top event of the fault tree is expressed as

[0019]

[0020] The probability of the top event of the fault tree is

[0021]

[0022] wherein, is the probability of each independent basic event occurrence;

[0023] basic event probability importance may be expressed as:

[0024]

[0025] wherein, represents the probability function of the transmitter fault tree, the importance degree of each basic event on the transmitter fault can be accurately quantified.

[0026] According to the radar fault positioning method of hierarchical fault tree modeling and probability analysis, the top event includes the fault of a transmitting system, a receiving system or a sky feed system.

[0027] According to the radar fault positioning method of hierarchical fault tree modeling and probability analysis, the logical relationship between adjacent two layers of events is an AND gate or an OR gate.

[0028] According to the radar fault positioning method of hierarchical fault tree modeling and probability analysis, the fault tree structure function of the transmitter is:

[0029]

[0030] In the formula, + represents OR, and × represents AND.

[0031] According to the radar fault positioning method of hierarchical fault tree modeling and probability analysis, the top event occurrence probability and the basic event probability importance are sorted to provide a fault troubleshooting priority.

[0032] The present application has the beneficial effects that: due to the complex structure of the radar system and the large number of components, when the state monitoring and signal collection are performed on the whole system, the qualitative and quantitative analysis results of the fault tree are combined, the reliable technical basis for the selection of monitoring points is provided on the basis of ensuring that the monitoring and diagnosis accuracy meets the system requirements, the diagnosis is more targeted and purposeful, the blind search and matching of faults are avoided, the number of monitoring points is reduced, the system operation amount is reduced, the rapid and accurate positioning of the radar fault is realized, the fault diagnosis efficiency is improved, and the radar maintenance efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a fault tree symbol diagram.

[0034] Figure 2 is a fault tree example diagram of a certain radar transmitter.

[0035] Figure 3 is a radar fault diagnosis system workflow diagram. DETAILED DESCRIPTION

[0036] The technical solutions of the present application are further described below in combination with the drawings.

[0037] A hierarchical fault tree modeling and probability analysis radar fault diagnosis method of the present application comprises the following steps:

[0038] Fault tree analysis is to take an undesired event (fault) of a system as the research object, locate all potential factors causing the fault (referred to as "top event") according to the function architecture and structure composition of the system, take these factors as secondary events (referred to as "intermediate events"), further find out all factors causing the secondary events, and deduce layer by layer until the direct factors at the end of the system (referred to as "bottom event") are traced back. After identifying various events by specific symbols, these events are associated into a tree-shaped graph by means of logic gate symbols, and a fault tree model corresponding to the system can be constructed. On this basis, through qualitative and quantitative analysis of the fault tree, the diagnosis of system fault can be realized. The fault tree model is a causal relationship model based on the structure and function of the diagnosis object, and can completely reflect the logical relationship between the fault phenomenon and the fault cause.

[0039] Top event: at the top of the fault tree, refers to the event that needs to be avoided most in system operation, i.e. system failure.

[0040] Intermediate event: a result event causing the top event, but not the bottom layer event of the fault tree, which is caused by the next level event. According to the complexity of the system, the intermediate event can contain multiple levels.

[0041] Bottom event: refers to the basic event at the bottom layer of the fault tree, representing the final cause that cannot be further decomposed.

[0042] Fault tree uses logic gates and symbols to connect bottom events, intermediate events and top events, including "or gate", "and gate" and "transfer symbol". When connecting events with "or gate", it means that as long as any child event occurs, the parent event will occur; when connecting events with "and gate", it means that only when all child events occur at the same time, the parent event will occur; "transfer symbol" is mostly used for complex fault trees or to represent the node association between different fault trees.

[0043] Suppose a fault tree contains independent bottom events, the top event of the fault tree is denoted as , and the state of each bottom event is denoted as . The top event can be represented by the state function of the bottom event as:

[0044]

[0045] where the logic function is called structure function.

[0046] If the state of the basic event is:

[0047]

[0048] The state of the top event can be expressed as:

[0049]

[0050] In the analysis framework of system fault tree, suppose that the set of all independent basic events of the system fault tree is which contains independent basic events, then the corresponding state vector is:

[0051]

[0052] If there is a subset whose corresponding state vector is:

[0053]

[0054] where is the number of basic events of the cut set, is the number of cut sets, is the cut vector. When the condition is met, it means that that is, when all the basic events contained in the subset (subsystem) occur, the top event will occur, so the subset is called a cut set.

[0055] If an arbitrary basic event is removed from a cut set, the remaining set no longer satisfies the definition of the cut set, then the cut set is called a minimal cut set. The minimal cut set represents a potential path for the occurrence of the top event, and the set of all minimal cut sets can completely cover all basic failure modes of the top event. Therefore, with the help of minimal cut sets, the weakest link or the area that needs to be focused on can be analyzed.

[0056] Establishing a system fault tree, identifying fault critical factors, and evaluating the importance of the impact of basic events on the top event are the basis for setting up signal monitoring points in complex systems to achieve intelligent fault diagnosis. Therefore, the quality of the establishment of the fault tree will directly affect the fault diagnosis results, and the steps for establishing the fault tree are as follows:

[0057] Step 1: Determine the top event of the fault tree .

[0058] Top event is the failure event occurred in system level. For complex system, the failure types include simple failure and difficult failure. If the structure integrity of fault tree is to be built, the difficult failure should be selected as top event. The top event is as follows:

[0059] 1. The top event must be the key problem of the research object, and its stability has a decisive role on system reliability. When the problem occurs, it will have a significant impact on the system;

[0060] 2. The top event should have the feasibility of being decomposed, and can further develop hierarchical fault analysis.

[0061] For example, in a radar system, the transmitting system, receiving system and antenna feeder system are more likely to fail, and the failure will seriously affect the performance of the radar. At the same time, each subsystem contains a large number of complex subsystems and electronic components, which may be the direct cause of the system failure. Therefore, the transmitting system failure, receiving system failure and antenna feeder system failure can be used as the top event of the radar system fault tree.

[0062] Step 2: Determine the boundary conditions.

[0063] For a certain top event, the boundary conditions of the fault tree should be reasonably analyzed to determine the scope of the fault tree. The boundary conditions of the fault tree should include three aspects:

[0064] 1. Initial state: refers to the working state of the components associated with the top event.

[0065] 2. Inadmissible event: refers to the event that is not allowed to occur during the establishment of the fault tree.

[0066] 3. Certain event: refers to the event that will certainly occur or certainly not occur during the system operation.

[0067] For example, the initial state of the transmitter failure top event of a radar system should be that the system is powered on and the switch is closed. The inadmissible event can be caused by external human factors leading to system failure. This can cover the main failure causes, solve more than 85% of the automatic positioning problem, and effectively reduce the analysis difficulty.

[0068] Step 3: Analyze the top event causes.

[0069] After determining the top event and boundary conditions of the research object, the causes of the top event should be analyzed, i.e. to find the secondary events. When analyzing the top event failure causes, the following four factors should be considered:

[0070] 1. Quality defects existing in the design and manufacture of the system;

[0071] 2. The component itself life attenuation or workload over limit, such as over service, exceeding the design load, etc.

[0072] 3. External environmental interference, such as rain, snow, fog, temperature, etc. on the system or component;

[0073] 4. Human factors, such as operation error, line connection error, etc.

[0074] Step 4: Establishing fault tree.

[0075] The fault tree is constructed from the top event as the starting point, and all potential causes leading to the top event need to be analyzed step by step to determine the intermediate events. Then, the next level of decomposition is carried out for each intermediate event until all bottom events causing the intermediate events are found. Finally, all events are connected by logical symbols to establish the fault tree model of the system. The logical relationship between the adjacent two layers of events mainly includes AND gate and OR gate connection.

[0076] Application example analysis of fault tree in radar fault detection: taking the transmitter as an example, the radar transmitter fault tree is established, and the radar transmitter fault tree is shown in Figure 2 The function of the radar transmitter is to amplify high-frequency signals through certain components, and then radiate these parts of high-frequency wireless signals through radio frequency, antenna and other modules. These signals are processed by the power amplifier circuit, and the processing components of the power amplifier circuit are the fault-prone modules. By using the fault tree analysis method, the system is analyzed, and the modules of the transmitter are accurately analyzed.

[0077] Figure 2 In the middle, the top event represents the transmitter failure. The intermediate event U1 represents the failure of the radio frequency module, U2 represents the failure of the power supply module, and U3 represents the failure of the transmitter power amplifier module. The bottom event X1 represents the frequency control failure, X2 represents the signal modulation failure, X3 represents the power amplifier component failure, X4 represents the transmitter overheating, X5 represents the power supply failure, and X6 represents the power supply module line failure.

[0078] Step 5: Qualitative analysis of fault tree.

[0079] By analyzing the cut sets and minimal cut sets of the system fault, the key factors of the fault are determined, and the logical relationship between the top event and the bottom event is constructed. All minimal cut sets in the system play a decisive role in preventing potential failure of the research object.

[0080] According to Figure 2 the transmitter fault tree structure diagram, the fault tree structure function is:

[0081]

[0082] In the formula, + represents OR, and × represents AND.

[0083] Thus, the fault tree has 6 minimal cut sets, which are .

[0084] Step 6: Quantitative analysis of the fault tree.

[0085] The probabilities of each bottom event are analyzed, and the probability of the top event failure is obtained through quantitative analysis according to the failure probabilities of each bottom event, and then the importance of the bottom event to the top event is evaluated.

[0086] The failure probability of the bottom event in the fault tree is usually determined based on the working experience of the staff, the failure probability of the minimal cut set is the product of the probabilities of all events, and the failure probability of the top event can be calculated by the probabilities of all minimal cut sets.

[0087] According to Figure 2 the transmitter fault tree structure diagram, it is assumed that the failure probability of the bottom event is Since each bottom event is independent of each other, the probability of the minimal cut set can be expressed as:

[0088]

[0089] In the formula, is the cut vector.

[0090] From the transmitter fault tree structure diagram, it can be seen that the minimal cut set Figure 2 of this model is a set composed of a single bottom event , so the probability of the minimal cut set of the transmitter fault tree can be expressed as:

[0091] ,

[0092] Thus, the probability of the top event of the transmitter fault tree can be expressed as the sum of the probabilities of all minimal cut sets, that is:

[0093]

[0094] Therefore, the probability of the top event of the transmitter fault tree is

[0095]

[0096] In the formula, is the probability of the occurrence of each independent bottom event.

[0097] The The probability importance of a bottom event represents the influence of a small change in the probability of the bottom event on the change of the probability of the top event. Because the bottom events in the transmitter fault tree are independent of each other, the probability importance of the bottom event can be represented as:

[0098]

[0099] In the formula, P (T) represents the probability function of the transmitter fault tree, P (B) represents the probability of the bottom event, and The probability importance of the bottom event can be accurately quantified.

[0100] The hierarchical fault model of the present application realizes the corresponding association of structure-function-fault of the radar system. Steps 1 to 4 establish the hierarchical model of the radar through the systematic fault tree establishment process, divide the structure, decompose and classify the functions of the radar, establish the hierarchical fault model, and can comprehensively and clearly sort out the logical relationship between the radar fault phenomenon and the fault cause, help the maintenance personnel to deeply understand the fault mechanism of the radar system, and avoid the problem of blind troubleshooting in the traditional fault diagnosis.

[0101] The present application combines qualitative analysis and quantitative analysis to form a structured diagnostic process of “first determining the core cause, and then troubleshooting according to the priority”. Step 5, with the help of the minimal cut set obtained through qualitative analysis, the maintenance personnel can determine the most basic cause combination leading to the radar fault, and grasp the key point of fault diagnosis. Step 6, through the top event occurrence probability and bottom event probability importance sorting obtained through quantitative analysis, the maintenance personnel can be provided with a scientific fault troubleshooting priority, and the components with high fault probability are checked first, which significantly improves the efficiency and accuracy of radar fault diagnosis.

[0102] The present application has strong universality and scalability, is not only suitable for the diagnosis of radar transmitter faults, but also can adjust the top event, intermediate event and bottom event of the fault tree according to the structure and fault characteristics of different types of radars, and is further applied to the fault diagnosis of other systems (such as receivers, antennas, terminals, etc.) of the radar, provides standardized and standardized technical support for radar maintenance work, and has wide practical application value.​

Claims

1. A radar fault location method based on hierarchical fault tree modeling and probabilistic analysis, characterized in that: Includes the following steps: Step 1: Determine the top event of the fault tree: The top event is the key issue of the research object, and the top event can be decomposed downwards; Step 2: Determine boundary conditions. For a given top event, reasonably analyze the boundary conditions of the fault tree. The boundary conditions of the fault tree include: the operating state of the components associated with the top event; events that are not allowed to occur as determined during the fault count establishment process; and events that will inevitably occur and events that will inevitably not occur during the system operation. Step 3: Analyze the cause of the top event: The cause of the top event should be analyzed, that is, to find the secondary events. When analyzing the cause of the top event failure; Step 4: Establish a fault tree: Starting from the top event, analyze all potential causes that led to the top event level by level, and then identify intermediate events; decompose each intermediate event into the next level until all the bottom events that caused the intermediate events are found; connect all events with logical symbols to establish a fault tree model of the system. Step 5: Qualitative analysis of the fault tree: Analyze the cut sets and minimum cut sets of the system faults, determine the key factors of the faults, and construct the logical relationship between the top event and the bottom event; Step 6: Quantitative analysis of the fault tree; analyze the probability of each bottom event, and based on the failure probability of each bottom event, obtain the probability of the top event of the system failing through quantitative analysis, and then assess the importance of the bottom events to the top event. Assuming the bottom event The probability of failure is Since the events at each base are independent of each other, the minimal cut set... The probability is expressed as: In the formula, It is a cut vector; Minimal cut set A set of individual base events Then the probability of the minimum cut set in the fault tree is expressed as: Probability of occurrence of the top event in the fault tree Represented as The probability of the top event in the fault tree is In the formula, Let be the probability of each independent base event occurring; Importance of the probability of a bottom event It can be represented as: In the formula, The probability function representing the transmitter fault tree. It can accurately quantify the impact of each underlying event on transmitter failure.

2. The radar fault location method based on hierarchical fault tree modeling and probabilistic analysis according to claim 1, characterized in that: Top events include failures in the transmitting system, receiving system, or antenna feeder system.

3. The radar fault location method based on hierarchical fault tree modeling and probabilistic analysis according to claim 1, characterized in that: The logical relationship between two adjacent event layers is an AND gate or an OR gate connection.

4. The radar fault location method based on hierarchical fault tree modeling and probabilistic analysis according to claim 1, characterized in that: The fault tree structure function for the transmitter is: In the formula, + represents OR and × represents AND.

5. The radar fault location method based on hierarchical fault tree modeling and probabilistic analysis according to claim 1, characterized in that: The probability of top events and the probability of bottom events are ranked in order of importance to provide a priority for troubleshooting.

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