A method for locating intermittent short circuit faults in a controller area network

Abstract

The application discloses a controller area network intermittent short circuit fault positioning method. The method comprises the following steps: firstly, modeling the CAN bus system as a switching system, each sending node corresponding to a subsystem, and modeling the subsystems by using a double-port network modeling method to describe the characteristics of the CAN bus circuit under different topological structures. When an intermittent short circuit fault occurs, a data acquisition sensor records error information and identifies the node address sending the error information. Then, the fault domain is determined by combining the voltage transmission difference equation set method with topological information and statistical significance. Finally, the accurate position of the ISC fault is determined by using a bidirectional eviction positioning algorithm. The method provided by the application is suitable for complex CAN bus topological structures, can be used for positioning the short circuit fault of a cable in a bus system, and provides an effective solution for fault diagnosis of the CAN bus system.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of controller area network fault diagnosis, and particularly relates to a controller area network (CAN) intermittent short-circuit fault locating method based on double-port network modeling. BACKGROUND

[0002] The controller area network (CAN) is a fieldbus capable of effectively supporting distributed and real-time control. Due to its good real-time performance, reliability, scalability and low cost, the CAN bus is widely used in vehicle communication systems, industrial automation control, aviation communication systems and other fields with strict reliability requirements. However, in actual application, improper human intervention, environmental interference, vibration and wear of electronic equipment and aging-related degradation may cause intermittent (IC) faults, thereby deteriorating the reliability of the network. The IC fault may interrupt normal message transmission, cause message transmission delay or loss, thereby deteriorating the quality of network service, reducing system performance, and in severe cases, communication errors caused by IC faults may cause nodes to enter a bus-off state, which may cause system-level faults in critical systems, increase the maintenance cost of the network, and even cause safety incidents. Therefore, it is crucial for the industrial application of the CAN bus to detect, locate and repair IC faults before they cause damage to the entire system.

[0003] There are various types of intermittent (IC) faults of the controller area network. At present, there is still no effective, practical and suitable online detection method for intermittent short-circuit (ISC) fault diagnosis for the data acquisition system of the existing method which needs to be embedded in the node. SUMMARY

[0004] The application aims to overcome the shortcomings of the existing fault diagnosis method, and proposes a controller area network intermittent short-circuit fault locating method based on double-port network modeling for the common intermittent short-circuit fault of the controller area network. The method proposed in the application overcomes the defects of the existing fault diagnosis method in intermittent short-circuit fault diagnosis, and correctly and effectively locates the occurrence position of the intermittent short-circuit fault by only collecting the network port voltage, without considering the reachability of the network, thereby ensuring the safety and reliability of the controller area network, and being applicable to various complex network topologies and single fault and multi-fault locating scenarios.

[0005] The technical scheme adopted by the application is as follows:

[0006] I. A controller area network intermittent short-circuit fault locating method

[0007] Step 1: Arrange the field programmable gate array (FPGA) based data acquisition sensor at the terminal of each branch of the controller area network, and continuously acquire the CAN signal of the corresponding branch terminal by using each data acquisition sensor when the controller area network has an intermittent short circuit fault;

[0008] Step 2: Extract and obtain the voltage of the corresponding sending node and all network terminals from each continuously acquired CAN signal;

[0009] Step 3: For the CAN signal at one time, the sending node N i corresponding to the current CAN signal is recorded as the main terminal T main , and the terminals of the controller area network except the main terminal T main are recorded as the secondary terminal T sub , then based on the voltage of all network terminals at the current time, the direction event of the current sending node N i is obtained by using the voltage transmission difference equation set; the direction event of the current sending node N i at different fault times is continuously processed and obtained, and then the fault domain and health domain corresponding to the main terminal T i of the current sending node N main and the fault domain and health domain corresponding to the secondary terminal T sub are generated.

[0010] Step 4: Repeat step 3, traverse and process the CAN signal of the corresponding branch terminal continuously acquired by each data acquisition sensor, obtain the fault domain and health domain corresponding to all main terminals T main and the fault domain and health domain corresponding to all secondary terminals T sub when the controller area network has an intermittent short circuit fault, and obtain the positioning diagnosis result of all ISC faults in the controller area network by using the fault domain and health domain corresponding to all main terminals T main and the fault domain and health domain corresponding to all secondary terminals T sub for bidirectional expulsion positioning of ISC fault.

[0011] In step 3, after judging the fault occurrence direction of the current sending node N i based on the voltage of all network terminals at the current time, the direction event of the current sending node N i is obtained; the direction event of the current sending node N i at different times is continuously processed and obtained, which is specifically:

[0012] Firstly, the link between the current sending node N i and the main terminal T main and the link between the current sending node N iand the secondary terminal T sub , the equivalent circuit of the primary link and the equivalent circuit of the secondary link are obtained; then according to the voltage of all network terminals at present, the voltage transfer difference function value of the equivalent circuit of the primary link and the voltage transfer difference function value of the equivalent circuit of the secondary link are calculated respectively by using the voltage transfer difference equation set method If the voltage transfer difference function value of the equivalent circuit of the primary link is less than the voltage transfer difference function value of the equivalent circuit of the secondary link , then the ISC fault occurs between the current sending node N i and the primary terminal T main , and the direction event of the current sending node N i is recorded as If the voltage transfer difference function value of the equivalent circuit of the secondary link is less than the voltage transfer difference function value of the equivalent circuit of the primary link , then the ISC fault occurs between the sending node N i and the secondary terminal T sub , and the direction event of the current sending node N i is recorded as

[0013] The calculation formula of the voltage transfer difference function value of the equivalent circuit of the primary link and the voltage transfer difference function value of the equivalent circuit of the secondary link is as follows:

[0014]

[0015] N i = Nx k , Ny k or Nz k

[0016] Wherein, x is the number of nodes on the first branch X with terminal resistance, y is the number of nodes on the second branch Y with terminal resistance, z is the number of nodes on the third branch Z without terminal resistance, and are respectively the voltage transfer difference function value of the equivalent circuit of the primary link and the voltage transfer difference function value of the equivalent circuit of the secondary link corresponding to the node Nz k on the third branch Z without terminal resistance, and are respectively the voltage transfer difference function value of the equivalent circuit of the primary link and the voltage transfer difference function value of the equivalent circuit of the secondary link corresponding to the node Nx k on the first branch X with terminal resistance, and​ The nodes Ny on the second branch Y with terminating resistors are respectively k The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and These are the terminal voltage and current matrices corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. These are the terminal voltages corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. and Let Q be the terminating resistors corresponding to the first branch X with a terminating resistor and the second branch Y with a terminating resistor, respectively. x The transmission parameter matrix O is the two-port network model consisting of X branches in a fault-free coupled unit. x The first line, Q y The transmission parameter matrix O of the two-port network model consisting of Y branches in a fault-free coupled unit. y The first line, Q z The transmission parameter matrix O of a two-port network model consisting of Z branches in a fault-free coupled unit. z The first line, V x V is the transmission parameter matrix of a two-port network model consisting of X branches in a faulty coupled unit. y V is the transmission parameter matrix of a two-port network model consisting of Y branches in a faulty coupled unit. z Let A be the transmission parameter matrix of a two-port network model consisting of Z branches in a faulty coupled unit. i A j A p A q Let B be the transmission parameter matrix of a two-port network model for the i-th, j-th, p-th, and q-th receiving nodes on any branch. k+1 Let A be the transmission parameter matrix A of a two-port network model for the (k+1)th receiving node on any branch. k+1 The first line, The short-circuit contact resistance R of a two-port network model for the (k+1)th fault node on any branch. S The first row B of the transmission parameter matrix of the model away from the terminal side S The short-circuit contact resistance R of a two-port network model with the (k+1)th fault node on any branch S The product of the transmission parameter matrices of the model closer to the terminal, where || represents the absolute value and T represents the transpose.

[0017] In step 3, the current sending node N is generated.i The main terminal T main The corresponding fault domain and health domain and secondary terminal T sub The corresponding fault domains and health domains are as follows:

[0018] If the current sending node N within the preset time period i If the proportion of a certain type of directional event occurs exceeds the preset fault occurrence coefficient, then the current sending node N will be... i The data path between the terminal corresponding to this type of directional event is denoted as the fault domain corresponding to the terminal corresponding to this type of directional event; if the current sending node N i If the proportion of a certain type of directional event is less than the preset fault occurrence coefficient, then the current sending node N will be... i The data path between the terminal corresponding to this type of directional event is denoted as the health domain corresponding to the terminal corresponding to this type of directional event; the current sending node N is traversed and processed. i After the two types of directional events, the current sending node N is obtained. i The main terminal T main The corresponding fault domain and health domain and secondary terminal T sub The corresponding fault domain and health domain.

[0019] In step 4, all major terminals T are utilized. main The corresponding fault domain and health domain and all secondary terminals T sub After performing bidirectional expulsion localization of ISC faults in the corresponding fault domain and health domain, the location and diagnosis results of all ISC faults in the controller area network are obtained, specifically:

[0020] The main terminal T of the controller local area network main The intersection of all fault domains minus the main terminal T main After unifying all health domains, the first fault location set is obtained; the secondary terminals T of the controller LAN are then... sub The intersection of all fault domains minus the secondary terminal T sub After taking the union of all health domains, the second fault location set is obtained; finally, the first fault location set and the second fault location set are taken as the union to obtain the location diagnosis results of all ISC faults in the controller local area network.

[0021] II. A computer device

[0022] The device includes a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps of the method for locating intermittent short-circuit faults in a controller area network.

[0023] III. A computer-readable storage medium

[0024] The medium stores a computer program, and the computer program is executed by a processor to implement the steps of the controller area network intermittent short circuit fault positioning method.

[0025] Four, a computer program product

[0026] The product includes computer programs / instructions, which are executed by a processor to implement the steps of the controller area network intermittent short circuit fault positioning method.

[0027] The beneficial effects of the present application are as follows:

[0028] The present application models the controller area network system of different nodes by using a two-port network modeling method to control the sending state, and develops a voltage transfer difference equation set based on the model, and develops a general diagnostic framework for various network topologies, especially for tree network topologies that cannot be handled by existing methods.

[0029] The present application is based on a voltage transfer difference equation set of two kinds of fault positioning subsystems respectively preset, and proposes a bidirectional expulsion positioning strategy to position various intermittent short circuit fault positions, including single fault and multi-fault scenarios. This method can position the ISC fault by only collecting the network port voltage, without considering the reachability of the network. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The subsystem equivalent circuit model is based on a two-port network modeling method.

[0031] Figure 2 The controller area network intermittent short circuit fault positioning method flowchart based on a two-port network modeling method.

[0032] Figure 3 It is a general receiving node two-port network model.

[0033] Figure 4 It is a receiving node two-port network model with a short circuit fault.

[0034] Figure 5 It is a general coupling unit two-port network model.

[0035] Figure 6 It is a coupling unit two-port network model with a short circuit fault. DETAILED DESCRIPTION

[0036] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] This invention proposes a method for locating intermittent short-circuit faults in controller area networks (Controller Area Networks) based on two-port network modeling. The invention models the subsystem to which a bus node belongs using a two-port network modeling approach. When an intermittent short-circuit fault occurs, data acquisition sensors locate the address of the node that emitted the erroneous information. The voltage information at different endpoints in the erroneous frame network is processed using a voltage transfer difference equation system algorithm, and then statistical calculations are performed based on the network topology obtained from the modeling to finally determine the location of the intermittent short-circuit fault. Figure 2 As shown, the specific steps include:

[0038] Step 1: Deploy data acquisition sensors based on Field Programmable Gate Arrays (FPGAs) at the terminals of each branch of the Controller Area Network (CAN). When a short-circuit fault (ISC fault) occurs, the corresponding differential voltage will be much lower than the normal dominant voltage; the corresponding signal is then extracted as the fault voltage. Simultaneously, the sending node address of this signal and the voltage of all network terminals, i.e., the fault voltage, are recorded. Therefore, this invention continuously acquires the CAN signals of the corresponding branch terminals using data acquisition sensors when an intermittent short-circuit fault occurs in the CAN.

[0039] Step 2: Extract and obtain the voltage of the corresponding transmitting node and all network terminals from each continuously acquired CAN signal;

[0040] Step 3: For a CAN signal at a given moment, the transmitting node N corresponding to the current CAN signal... i The terminal of the branch is denoted as the primary terminal T. main And in addition to the main terminal T in the controller LAN main Terminals other than these are referred to as secondary terminals T. sub Next, the direction event of the current transmitting node Ni is obtained using the voltage transfer difference equations; the process continues to obtain the current transmitting node N. i Directional events at different times are used to generate the current sending node N. i The main terminal T main The corresponding fault domain and health domain and secondary terminal T sub The corresponding fault domain and health domain;

[0041] In step 3, based on the voltage of all current network terminals, determine the current sending node N.i the direction of the fault occurrence; the direction event of the current sending node N i is obtained; the direction events of the current sending node N i at different time instants are continuously processed and obtained, specifically:

[0042] First, as shown in Figure 1 , the link between the current sending node N i and the primary terminal T main and the link between the current sending node N i and the secondary terminal T sub are modeled respectively by using the two-port network modeling method, to obtain the equivalent circuit of the primary link and the two-port network model of the secondary link; then, according to the voltages of all the network terminals at present, the voltage transfer difference function values of the equivalent circuit of the primary link and the equivalent circuit of the secondary link are calculated respectively by using the voltage transfer difference function group (VTDFG) method. The voltage transfer difference function values calculated can be compared to obtain the "direction event" of the sending node, i.e., at which terminal between the sending node and which terminal the ISC fault occurs. The specific comparison method is as follows: if the voltage transfer difference function value of the equivalent circuit of the primary link is less than the voltage transfer difference function value of the equivalent circuit of the secondary link , then the ISC fault occurs between the current sending node N i and the primary terminal T main , and the direction event of the current sending node N i is recorded as If the voltage transfer difference function value of the equivalent circuit of the secondary link is less than the voltage transfer difference function value of the equivalent circuit of the primary link , then the ISC fault occurs between the sending node N i and the secondary terminal T sub , and the direction event of the current sending node N i is recorded as The voltage transfer difference function value of the equivalent circuit of the primary link is equal to the voltage transfer difference function value of the equivalent circuit of the secondary link , which means that no fault occurs. This case does not exist on the basis of fault occurrence.

[0043] The CAN bus system is modeled as a switching system, each sending node corresponds to a subsystem, and the subsystems are modeled using a two-port network modeling method to describe the characteristics of the CAN bus circuit under different topologies. Based on the two-port network modeling method, the subsystem of the controller area network bus is modeled as a subsystem circuit composed of sending nodes, receiving nodes, fault nodes and coupling units, where each component can be described by a two-port network. The mathematical modeling of different components is as follows:

[0044] As shown in Figure 3 , the receiving node is responsible for receiving data in the circuit, which is composed of a differential resistance and two cable resistances, and the transfer model of its current-voltage relationship is:

[0045]

[0046] As shown in Figure 4 , the fault node is the short-circuit contact resistance R s between the cable resistances. The transfer model of the current-voltage relationship of the receiving node connected to the fault node is:

[0047]

[0048] where R s represents the short-circuit contact resistance of the fault node.

[0049] The coupling unit represents the intersection of branches in the network topology, as shown in Figure 5 , when there is no fault, the transfer model of its current-voltage relationship is:

[0050]

[0051] As shown in Figure 6 , when there is a short-circuit fault in the coupling unit, the transfer model of its current-voltage relationship is:

[0052]

[0053] where U i+1 and U i are the differential voltages of the i+1th node and the ith node on any branch, respectively, I i and I i-1 are the currents at the ith node and the i-1th node on any branch, respectively, R i is the differential internal resistance of the ith node on any branch, r is the resistance of the cable between the two nodes, and B i is the first row of the transmission parameter matrix A i of the two-port network model of the ith receiving node on any branch, BS Let R be the short-circuit contact resistance of the two-port network model for the i-th fault node on any branch. S The first row of the transmission parameter matrix for the model furthest from the terminal. For B S The short-circuit contact resistance R of a two-port network model with the i-th fault node on any branch S The product of the transmission parameter matrices of the model closer to the terminal, o y The transmission parameter matrix of a two-port network model consisting of Y branches in a fault-free coupled unit is given by o. z U is the transmission parameter matrix of a two-port network model consisting of Z branches in a fault-free coupled unit. x U y U z These are the nodes adjacent to the coupling unit on branches X, Y, and Z, respectively (i.e. Figure 1 Middle node x x ,y y ,z z The differential voltage of ,) I x I y and I z These are the nodes adjacent to the coupling unit on branches X, Y, and Z, respectively (i.e. Figure 1 Middle node x x ,y y ,z z The current R y and R z These are the nodes adjacent to the coupling unit on branches Y and Z, respectively. Figure 1 Middle node y y ,z z The differential internal resistance of O is ,) y and O z These are the transmission parameter matrices of a two-port network model consisting of Y and Z branches in a fault-free coupled unit, and Q. y and Q z O y and O z The first line, U k Let v be the differential voltage of the k-th transmitting node on any branch. y and v z These are the transmission parameter matrices of a two-port network model consisting of Y and Z branches in a faulty coupled unit.

[0054] Voltage transfer difference function value of the equivalent circuit of the main link and the voltage transfer difference function value of the secondary link equivalent circuit. The calculation formula is as follows:

[0055]

[0056] N i =Nx k 、Ny k or Nz k

[0057] Where x is the number of nodes on the first branch X with a terminating resistor, y is the number of nodes on the second branch Y with a terminating resistor, and z is the number of nodes on the branch Z without a terminating resistor. and The nodes Nz on the branch Z without terminating resistors are respectively k The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and The nodes Nx on the first branch X with terminating resistors are respectively k The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and The nodes Ny on the second branch Y with terminating resistors are respectively k The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and These are the terminal voltage and current matrices corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. These are the terminal voltages corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. and Let Q be the terminating resistors corresponding to the first branch X with a terminating resistor and the second branch Y with a terminating resistor, respectively. x The transmission parameter matrix O is the two-port network model consisting of X branches in a fault-free coupled unit. x The first line, Q y The transmission parameter matrix O of the two-port network model consisting of Y branches in a fault-free coupled unit. y The first line, Q z The transmission parameter matrix O of a two-port network model consisting of Z branches in a fault-free coupled unit. z The first line, V x V is the transmission parameter matrix of a two-port network model consisting of X branches in a faulty coupled unit. y V is the transmission parameter matrix of a two-port network model consisting of Y branches in a faulty coupled unit. z Let A be the transmission parameter matrix of a two-port network model consisting of Z branches in a faulty coupled unit.i A j A p A q Let B be the transmission parameter matrix of a two-port network model for the i-th, j-th, p-th, and q-th receiving nodes on any branch. k+1 Let A be the transmission parameter matrix A of a two-port network model for the (k+1)th receiving node on any branch. k+1 The first line, The short-circuit contact resistance R of a two-port network model for the (k+1)th fault node on any branch. S The first row B of the transmission parameter matrix of the model away from the terminal side S The short-circuit contact resistance R of a two-port network model with the (k+1)th fault node on any branch S The product of the transmission parameter matrices of the model closer to the terminal, where || represents the absolute value and T represents the transpose.

[0058] Among them, the current sending node N is generated. i The main terminal T main The corresponding fault domain and health domain and secondary terminal T sub The corresponding fault domains and health domains are as follows:

[0059] As the ISC failure persists over time, each transmitting node has a sufficient number of directional events. Within a preset time, if the current transmitting node N... i If the proportion of a certain type of directional event occurs exceeds the preset fault occurrence coefficient, then the current sending node N will be... i The data path between the terminal corresponding to this type of directional event is denoted as the fault domain corresponding to the terminal corresponding to this type of directional event; if the current sending node N i If the proportion of a certain type of directional event is less than the preset health maintenance coefficient, then the current sending node N will be... i The data path between the terminal corresponding to this type of directional event is denoted as the health domain corresponding to the terminal corresponding to this type of directional event; the current sending node N is traversed and processed. i After the two types of directional events, the current sending node N is obtained. i The main terminal T main The corresponding fault domain and health domain and secondary terminal T sub The corresponding fault domain and health domain. (Using...) Indicates sending node N i and terminal T h All data paths between them, h = sub or main, Indicates sending node N i and terminal T h All physical links in the data path between terminals T. If terminal Th If the proportion of the corresponding direction event (i.e. the proportion of the total direction event within the preset time) is greater than the preset fault occurrence coefficient, it is considered that the ISC fault occurs in All links in the fault domain are considered to have occurred ISC fault Similarly, if the terminal T h If the proportion of the corresponding direction event is less than the preset health maintenance coefficient, it is considered that the ISC fault does not occur in The health domain is defined

[0060] Step 4: Repeat step 3 to traverse and process each data acquisition sensor to continuously collect the CAN signal of the corresponding branch terminal, and obtain all main terminals T main The corresponding fault domain and the health domain and all secondary terminals T sub The corresponding fault domain and the health domain, all main terminals T main The corresponding fault domain and the health domain and all secondary terminals T sub After the bidirectional expulsion positioning (BEL) of the ISC fault of the corresponding fault domain and the health domain, the positioning diagnosis result of all ISC faults in the controller area network is obtained, and the obtained fault information is stored and reported for later network diagnosis and fault repair.

[0061] Wherein, all main terminals T main The corresponding fault domain and the health domain and all secondary terminals T sub After the bidirectional expulsion positioning (BEL) of the ISC fault of the corresponding fault domain and the health domain, the positioning diagnosis result of all ISC faults in the controller area network is obtained, and the obtained fault information is stored and reported for later network diagnosis and fault repair.

[0062] The intersection of all fault domains of the main terminal T main of the controller area network is subtracted from the union of all health domains of the main terminal T main to obtain a first fault location set The intersection of all fault domains of the secondary terminal T sub of the controller area network is subtracted from the union of all health domains of the secondary terminal T sub to obtain a second fault location set That is n represents the total number of sending nodes. Finally, the first fault location set and the second fault location set are taken as a union to obtain the positioning diagnosis result ISC of all ISC faults in the controller area network Network That is

[0063] Finally, it should be noted that the above examples and descriptions are only used to illustrate the technical solutions of the present application and not to limit the present application. Those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions disclosed by the present application, and all should be covered in the protection scope of the claims of the present application.

Claims

1. A method for locating intermittent short-circuit faults in a controller area network, characterized in that The method comprises the following steps: Step 1: arranging a field programmable gate array (FPGA) based data acquisition sensor at the terminal of each branch of the controller area network, and continuously acquiring the CAN signal of the corresponding branch terminal by using each data acquisition sensor when the controller area network has an intermittent short circuit fault; Step 2: extracting and obtaining the voltage of the corresponding sending node and all network terminals from each continuously acquired CAN signal; Step 3: for a time instant of CAN signal, the terminal of the branch where the current CAN signal corresponds to sending node N i is recorded as the main terminal T main , and the terminals in the CAN other than the main terminal T main are recorded as the secondary terminals T sub ; then based on the voltage of all network terminals at present, the voltage transmission difference equation set is used to obtain the direction event of the current sending node N i ; the direction event of the current sending node N i at different fault time instants is continuously processed and obtained, and the fault domain corresponding to the main terminal T i of the current sending node N main and the fault domain and health domain corresponding to the secondary terminals T sub are generated; Step 4: Repeat Step 3 to continuously collect CAN signals of corresponding branch terminals for each data acquisition sensor to obtain all main terminals T main Corresponding fault domain and health domain and all secondary terminals T sub Corresponding fault domain and health domain, all main terminals T main Corresponding fault domain and health domain and all secondary terminals T sub After bidirectional expulsion positioning of the ISC fault in the corresponding fault domain and health domain, the positioning and diagnosis results of all intermittent short circuit (ISC) faults in the controller area network are obtained. In step 3, based on the voltage of all network terminals at present, the failure occurrence direction of the current sending node N i is determined, and the direction event of the current sending node N i is obtained; the direction event of the current sending node N i at different time points is continuously processed and obtained, specifically as follows: Firstly, the link between the current sending node N i and the main terminal T main and the link between the current sending node N i and the secondary terminal T sub are modeled respectively by using the two-port network modeling method, and the equivalent circuit of the main link and the equivalent circuit of the secondary link are obtained; then, according to the voltage of all the network terminals, the voltage transfer difference function value of the equivalent circuit of the main link and the voltage transfer difference function value of the equivalent circuit of the secondary link are calculated respectively by using the voltage transfer difference equation set method; if the voltage transfer difference function value of the equivalent circuit of the main link is less than the voltage transfer difference function value of the equivalent circuit of the secondary link , then the intermittent short circuit (ISC) fault occurs between the current sending node N i and the main terminal T main , and the direction event of the current sending node N i is recorded as ; if the voltage transfer difference function value of the equivalent circuit of the secondary link is less than the voltage transfer difference function value of the equivalent circuit of the main link , then the intermittent short circuit (ISC) fault occurs between the current sending node N i and the secondary terminal T sub , and the direction event of the current sending node N i is recorded as .

2. The method of claim 1, wherein, The voltage transfer difference function value of the primary link equivalent circuit and the voltage transfer difference function value of the secondary link equivalent circuit The calculation formula is as follows: ， Where x is the number of nodes on the first branch X with a terminating resistor, y is the number of nodes on the second branch Y with a terminating resistor, and z is the number of nodes on the branch Z without a terminating resistor. and These are nodes on branch Z without terminating resistors. The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and The nodes on the first branch X with terminating resistors are respectively The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. and These are the nodes on the second branch Y with terminating resistors. The voltage transfer difference function values ​​of the corresponding primary link equivalent circuit and the voltage transfer difference function values ​​of the secondary link equivalent circuit. , and These are the terminal voltage and current matrices corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. , , These are the terminal voltages corresponding to the first branch X with a terminating resistor, the second branch Y with a terminating resistor, and the branch Z without a terminating resistor, respectively. and These are the terminating resistors corresponding to the first branch X with a terminating resistor and the second branch Y with a terminating resistor, respectively. The transmission parameter matrix of a two-port network model consisting of X branches in a fault-free coupled unit. The first line, The transmission parameter matrix of a two-port network model consisting of Y branches in a fault-free coupled unit. The first line, The transmission parameter matrix of a two-port network model consisting of Z branches in a fault-free coupled unit. The first line, This represents the transmission parameter matrix of a two-port network model consisting of X branches within a faulty coupled unit. This represents the transmission parameter matrix of a two-port network model consisting of Y branches in a faulty coupled unit. This represents the transmission parameter matrix of a two-port network model consisting of Z branches in a faulty coupled unit. , , , Aik+1is the transmission parameter matrix of the two-port network model of the k+1th receiving node on the arbitrary branch, Aik+1is the transmission parameter matrix of the two-port network model of the k+1th receiving node on the arbitrary branch, k+1 the first row of the transmission parameter matrix of the model on the terminal side, Rik+1is the short-circuit contact resistance of the two-port network model of the k+1th fault node on the arbitrary branch, S the first row of the transmission parameter matrix of the model on the terminal side, Rik+1is the short-circuit contact resistance of the two-port network model of the k+1th fault node on the arbitrary branch, S the product of the transmission parameter matrix of the model on the terminal side, is the absolute value, and T represents the transpose.

3. The method of claim 1, wherein, In step 3, the current sending node N i The primary terminal T main The corresponding failure domain and the health domain and the secondary terminal T sub The corresponding failure domain and the health domain, specifically: If the proportion of a certain type of directional event occurring in the current sending node N i is greater than a preset failure occurrence coefficient within a preset time, the data path between the current sending node N i and the terminal corresponding to the type of directional event is recorded as the failure domain corresponding to the terminal corresponding to the type of directional event; if the proportion of a certain type of directional event occurring in the current sending node N i is less than a preset failure occurrence coefficient, the data path between the current sending node N i and the terminal corresponding to the type of directional event is recorded as the health domain corresponding to the terminal corresponding to the type of directional event; after processing the two types of directional events of the current sending node N i , the failure domain and the health domain corresponding to the main terminal T main and the failure domain and the health domain corresponding to the secondary terminal T sub of the current sending node N i are obtained.

4. The method of claim 1, wherein, In step 4, all primary terminals T main The corresponding fault domain and the health domain and all secondary terminals T sub After the bidirectional expulsion positioning of the intermittent short circuit (ISC) fault of the corresponding fault domain and the health domain, the positioning diagnosis result of all intermittent short circuit (ISC) faults in the controller area network is obtained, which is specifically: The main terminal T of the controller local area network main The intersection of all fault domains minus the main terminal T main After unifying all health domains, the first fault location set is obtained; the secondary terminals T of the controller LAN are then... sub The intersection of all fault domains minus the secondary terminal T sub After taking the union of all health domains, the second fault location set is obtained; finally, the first fault location set and the second fault location set are combined to obtain the location diagnosis results of all intermittent short circuit (ISC) faults in the controller area network. 5.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-4 when the computer program is executed by the processor. The processor executes the computer program to realize the steps of the controller area network intermittent short circuit fault positioning method in any one of claims 1 to 4.

6. A computer-readable storage medium having stored thereon a computer program, characterized in that, The computer program is executed by the processor to realize the steps of the controller area network intermittent short circuit fault positioning method in any one of claims 1 to 4.

7. A computer program product comprising computer programs / instructions, characterized in that, The computer program / instruction is executed by the processor to realize the steps of the controller area network intermittent short circuit fault positioning method in any one of claims 1 to 4.

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