Fault detection method and device for vehicle CAN bus and storage medium

Abstract

The application relates to the field of vehicle CAN networks, in particular to a fault detection method and device for a vehicle CAN bus and a storage medium. The method comprises the following steps: in the case that all elements on the CAN bus are powered off, resistance sampling is performed on preset key points; in the case that all elements on the CAN bus are powered on and electric control parts on the CAN bus are in a communication state, voltage sampling is performed on the preset key points; and based on the topology of the CAN bus, the sampled resistance and voltage, a fault type and a fault point are determined.

Description

Technical Field

[0001] This application relates to the field of vehicle CAN (Controller Area Network) networks, and more specifically, to a method, apparatus, and storage medium for fault detection of a vehicle CAN bus. Background Technology

[0002] Currently, almost all electronic control components in vehicles use the CAN bus for communication and interaction. The most significant characteristic of the CAN bus is its one-to-many transmission mechanism; once one electronic control component sends a message, all other electronic control components on the bus can receive it. Similarly, if any point on the CAN bus is interfered with, the entire CAN bus will be affected. Furthermore, electronic control components connected to the CAN bus, as well as their connectors and wiring harnesses, can be susceptible to faults. These faults may include poor soldering or short circuits on the circuit boards of electronic control components, poor contact at connector pins, and short circuits or open circuits in the wiring harness.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] To address or at least mitigate one or more of the above problems, the following technical solutions are provided. The fault detection method, apparatus, and storage medium for vehicle CAN bus according to this application can solve the problems of difficulty in detecting, troubleshooting, and locating physical layer faults in the CAN bus.

[0005] According to a first aspect of this application, a fault detection method for a vehicle CAN bus is provided, the method comprising the following steps: when all components on the CAN bus are de-energized, performing resistance sampling on preset key points; when all components on the CAN bus are energized and the electronic control components on the CAN bus are in communication mode, performing voltage sampling on the preset key points; and determining the fault type and fault location based on the topology of the CAN bus, the sampled resistance and voltage.

[0006] According to an embodiment of the present application, a fault detection method for a vehicle CAN bus is provided, wherein the method further includes: displaying the determined fault type and fault point on a screen in a visual manner.

[0007] According to an embodiment of the present application, a fault detection method for a vehicle CAN bus includes the following preset key points: the connection points between the main harness and the branch harness or daisy-chain harness of the CAN bus; the connection points between each component and the main harness, the branch harness or the daisy-chain harness; the components on the CAN bus include: terminating resistors; electronic control components connected in parallel to the main harness via the branch harness, and / or connected in series to the main harness via the daisy-chain harness.

[0008] According to an embodiment of this application, a fault detection method for a vehicle CAN bus, wherein determining the fault type and fault point based on the topology of the CAN bus, sampled resistance, and voltage includes: detecting steady-state bus faults by comparing the sampled resistance with a preset resistance value; and detecting transient bus faults by comparing the voltage waveforms at each preset key point.

[0009] According to a second aspect of this application, a fault detection device for a vehicle CAN bus is provided. The device includes: a fault sampling unit configured to: perform resistance sampling on a preset key point when all components on the CAN bus are de-energized; and perform voltage sampling on the preset key point when all components on the CAN bus are energized and the electronic control components on the CAN bus are in a communication state; and a fault evaluation unit configured to: determine the fault type and fault point based on the topology of the CAN bus, the sampled resistance, and the voltage.

[0010] According to an embodiment of this application, a fault detection device for a vehicle CAN bus is provided, wherein the device further includes a fault display unit configured to display the determined fault type and fault point on a screen in a visual manner.

[0011] According to an embodiment of this application, a fault detection device for a vehicle CAN bus includes the following preset key points: the connection points between the main harness and the branch harness or daisy-chain harness of the CAN bus; the connection points between each component and the main harness, the branch harness or the daisy-chain harness; the components on the CAN bus include: terminating resistors; electronic control components connected in parallel to the main harness via the branch harness, and / or connected in series to the main harness via the daisy-chain harness.

[0012] According to an embodiment of this application, a fault detection device for a vehicle CAN bus is provided, wherein the fault evaluation unit is further configured to: detect steady-state bus faults by comparing a sampled resistor with a preset resistor value; and detect transient bus faults by comparing voltage waveforms at preset key points.

[0013] According to a third aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium storing instructions, characterized in that, when the instructions are executed by a processor, the processor causes the processor to perform the method described in the first aspect of this application.

[0014] The fault detection scheme for vehicle CAN bus according to one or more embodiments of this application detects steady-state bus faults by resistance method and detects transient bus faults by voltage waveform comparison method and accurately locates the fault point, solving the "three difficulties" problem that engineers have long complained about: difficulty in finding, troubleshooting and locating CAN bus physical layer faults. Attached Figure Description

[0015] The above and / or other aspects and advantages of this application will become clearer and more readily understood from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are denoted by the same reference numerals. The drawings include:

[0016] Figure 1 A schematic block diagram of a fault detection device 10 for a vehicle CAN bus according to an embodiment of this application is shown.

[0017] Figure 2 A schematic structural diagram of a CAN bus physical layer and its fault detection device according to an embodiment of this application is shown; and

[0018] Figure 3 A schematic flowchart of a fault detection method 30 for a vehicle CAN bus according to an embodiment of this application is shown. Detailed Implementation

[0019] This application is described more fully in this specification with reference to the accompanying drawings, which illustrate exemplary embodiments thereof. However, this application may be implemented in various forms and should not be construed as limited to the embodiments given herein. The embodiments given are intended to make the disclosure herein complete and thorough, so as to more fully convey the scope of protection of this application to those skilled in the art.

[0020] Terms such as "comprising" and "including" indicate that, in addition to the units and steps that are directly and explicitly stated in the specification and claims, the technical solution of this application does not exclude the presence of other units and steps that are not directly or explicitly stated. Terms such as "first" and "second" do not indicate the order of the units in terms of time, space, size, etc., but are merely used to distinguish the units.

[0021] The present application is described below with reference to flowchart illustrations, block diagrams, and / or flowcharts of methods and systems according to embodiments of the present application. It will be understood that each block of these flowchart illustrations and / or block diagrams, and combinations thereof, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to form a machine, such that these instructions, executable by the processor of the computer or other programmable data processing apparatus, create components for implementing the functions / operations specified in these flowchart illustrations and / or blocks and / or one or more flowchart illustrations. It should also be noted that in some alternative implementations, the functions / operations shown in the blocks may not occur in the order shown in the flowchart. For example, two blocks shown sequentially may actually be executed substantially simultaneously, or these blocks may sometimes be executed in reverse order, depending on the functions / operations involved.

[0022] These computer program instructions can be loaded onto a computer or other programmable data processor to cause a series of operational steps to be executed on the computer or other programmable processor, thereby constituting a computer-implemented process, such that these instructions, which execute on the computer or other programmable data processor, provide steps for implementing the functions or operations specified in one or more boxes of this flowchart and / or block diagram. It should also be noted that in some alternative implementations, the functions / operations shown in the boxes may not occur in the order shown in the flowchart. For example, two boxes shown sequentially may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order, depending on the functions / operations involved.

[0023] The CAN bus, also known as the automotive bus, connects various electronic control units (ECUs) within a vehicle into a local area network, enabling information sharing and significantly reducing the amount of wiring in the car. When an ECU sends a message, it transmits this message to all ECUs on the CAN bus by changing the differential voltage between the twisted pairs of wires. If the bus voltage is interfered with during message transmission, and any ECU detects a voltage different from the voltage sent by the transmitter, the message transmission will fail. Multiple transmission failures will lead to malfunctions in the vehicle. ECUs are generally connected to the CAN bus via branch lines or daisy-chain connections. Faults can occur in the ECUs themselves, connectors, and wiring harnesses, such as poor soldering or short circuits on ECU circuit boards, poor contact at connector pins, and short circuits or open circuits in the wiring harness. Furthermore, faults can sometimes be steady-state reproducible, such as steady-state short circuits or open circuits. While using a multimeter to check the continuity of the entire CAN bus can relatively easily detect the type of fault, it is still difficult to pinpoint the exact location of the fault. Furthermore, most faults are transient, such as brief contact malfunctions, especially during road tests on bumpy roads. Transient faults can be introduced into all connections on the entire CAN bus, causing CAN bus abnormalities and consequently, vehicle malfunctions. These types of faults cannot be detected with simple devices like multimeters, and they are difficult to reproduce afterward, making it impossible to pinpoint the fault location or determine the time of failure. To address this, this application proposes a fault detection scheme for the vehicle CAN bus. This scheme can detect steady-state bus faults using a resistance method and detect transient bus faults using a voltage waveform comparison method, accurately locating the fault point. This solves the problems of difficulty in discovering, troubleshooting, and locating CAN bus physical layer faults.

[0024] Now for reference Figure 1 , Figure 1 A schematic block diagram of a fault detection device 10 for a vehicle CAN bus according to an embodiment of this application is shown. Figure 1 As shown, the fault detection device 10 includes a fault sampling unit 110 and a fault evaluation unit 120. Optionally, the fault detection device 10 also includes a fault display unit 130.

[0025] A CAN bus typically includes wiring harnesses, terminating resistors, and several electronic control components. Wiring harnesses include bus harnesses, branch harnesses, daisy-chain harnesses, etc., each consisting of two twisted-pair cables. Daisy-chain harnesses consist of two sets of twisted-pair cables. Wiring harnesses may experience faults such as poor contact at branch points, open circuits, and short circuits.

[0026] Typically, a single CAN bus can support up to dozens of electronically controlled components (ECUs). These ECUs can be connected in parallel to the main bus via branch harnesses or in series via daisy-chain harnesses. Once powered on, these ECUs can send specific voltage waveforms to the CAN bus to transmit information. On one hand, the circuitry of the ECUs themselves may be faulty, such as poor soldering or short circuits on the circuit board. On the other hand, since most ECUs are connected to the harness via connectors, these connectors may also have issues such as loose pin connections or poor contact.

[0027] In addition, the CAN bus can also accommodate some aftermarket devices, such as data acquisition tools like voltage and current sensors. During vehicle calibration and various testing phases, these data acquisition tools are typically installed on the CAN bus to store bus messages. However, this also introduces new fault factors into the CAN bus. The types of faults that aftermarket devices may experience are similar to those of the aforementioned electronic control components.

[0028] Before using the fault detection device 10 to perform fault detection on the CAN bus, several key points need to be preset on the CAN bus for subsequent resistance and voltage monitoring. Optionally, the preset key points include one or more of the following: the connection points between the main harness and the branch harness or daisy chain harness of the CAN bus; the connection points between each component (e.g., terminating resistors, electronic control components, data acquisition tools) and the main harness, branch harness or daisy chain harness.

[0029] The fault sampling unit 110 is configured according to the physical topology of the CAN bus currently under test. The fault sampling unit is connected to a preset key point on the CAN bus harness. The fault sampling unit 110 can be used to sample the resistance of the preset key point when all components on the CAN bus are de-energized. The fault sampling unit 110 can also be used to sample the voltage of the preset key point when all components on the CAN bus are energized and the electronically controlled components on the CAN bus are in communication (e.g., the electronically controlled components are sending messages to each other).

[0030] The fault assessment unit 120 is configured to determine the fault type and fault location based on the CAN bus topology, sampled resistance, and voltage, and can also provide troubleshooting directions. For example, when all devices on the CAN bus are powered on, the fault assessment unit 120 can compare the resistance collected by the fault sampling unit 110 with preset resistance values ​​(e.g., 0Ω, 60Ω, 120Ω), and combine this with the topology of the CAN bus physical layer under test to determine whether there are steady-state short circuits, open circuits, or other faults on the bus, and locate the fault to a specific wire harness or component. The fault assessment unit 120 can also, when all devices on the CAN bus are powered on, compare the voltage waveform collected by the fault sampling unit 110, and combine this with the topology of the CAN bus physical layer under test to determine whether there are transient short circuits, open circuits, or other faults on the bus, and locate the fault to a specific wire harness or component.

[0031] The fault display unit 130 primarily functions to interact with external information. For example, before configuring preset key points, the topology of the CAN bus physical layer to be tested (e.g., terminating resistors, electronic control components, connection methods, etc.) can be input into the fault display unit 130. The fault display unit 130 can also display the fault type and fault point assessed by the fault assessment unit 120, and show the corresponding troubleshooting direction.

[0032] The following is for reference. Figure 2 , Figure 2 A schematic structural diagram of a CAN bus physical layer and its fault detection device according to an embodiment of this application is shown.

[0033] like Figure 2 As shown, the CAN bus 12 includes two sets of terminating resistors, namely terminating resistor 1 and terminating resistor 2, which are connected to both ends of the CAN bus respectively. These resistors are responsible for improving the bus's anti-interference capability and reducing signal reflection. Each set of terminating resistors consists of two 60Ω resistors connected in series. Terminating resistors may experience faults such as open circuits or short circuits. The CAN bus also includes electronic control components 8, 10, and 11, as well as a data acquisition tool 9. The CAN bus wiring harness includes bus wiring harness 3, branch wiring harness 4, branch wiring harness 5, daisy-chain wiring harness 6, and branch wiring harness 7. Electronic control components can be directly connected to the CAN bus wiring harness via branch wiring harnesses or connected in series via daisy-chain wiring harnesses.

[0034] The CAN bus physical layer fault detection device 13 includes a fault sampling unit 14, a fault evaluation unit 15, and a fault display unit 16. The fault sampling unit 14 is directly connected to each key point in the CAN bus 12 (points A, a, B, b, C, c, D, d, E, e, F, f, G, g, H, h, J, j, K, k, M, m in the figure). It samples the resistance of each key point when all devices in the CAN bus 12 are powered off, and samples the voltage waveform of each key point when all devices in the CAN bus 12 are powered on. The fault evaluation unit 15, based on the input from the fault sampling unit 14 and combined with internal logic operations, compares the sampled resistance value with a standard value and compares the voltage waveform of each sampling point to determine the fault type and fault location, while also providing troubleshooting directions. The fault display unit 16 displays the fault status and fault location evaluated by the fault evaluation unit 15 in real time and provides corresponding troubleshooting directions.

[0035] For example, the detection steps of the CAN bus physical layer fault detection device 13 include one or more of the following:

[0036] Input CAN bus topology: Input the topology information of the CAN bus to be tested into the fault display unit 16, including terminating resistors, electronic control components, connection methods, etc. This step prepares for the subsequent connection of the CAN bus circuit and the location of the fault point.

[0037] Connecting the CAN bus circuit: With the electronic control components 8, data acquisition tool 9, electronic control components 10 and 11 in the CAN bus 12 all de-energized, connect the sampling points A, a, B, b, C, c, D, d, E, e, F, f, G, g, H, h, J, j, K, k, M, m of the fault sampling unit 14 in the fault detection device 13 to the corresponding monitoring points in the CAN bus 12.

[0038] Detecting steady-state bus faults: With the electronic control components 8, 9, 10, and 11 in the CAN bus 12 all de-energized, measure the resistance between the following two points: A and a, B and b, C and c, D and d, E and e, F and f, G and g, H and h, J and j, K and k. The fault assessment unit 15 will provide an assessment result based on several resistance results:

[0039] (a) If the resistance is around 60Ω, the fault display unit 16 indicates that there is no obvious steady-state fault on this CAN bus.

[0040] (b) If all resistances are around 120Ω, the fault display unit 16 indicates that the CAN bus is stably in an open-circuit state. The cause of the open circuit may be terminating resistor 1, terminating resistor 2, electronic control component 10, or bus harness 3. In this case, each component needs to be checked one by one. For example, disconnect / reconnect terminating resistor 1, terminating resistor 2, and electronic control component 10 in sequence. If the resistance test results change after disconnection (i.e., the resistance is no longer around 120Ω), then the main harness 3 is faulty; if the resistance test results do not change after disconnection (i.e., the resistance is still around 120Ω), then the currently disconnected device is faulty.

[0041] (c) If all resistances are around 0Ω, it indicates that the CAN bus is stably in a short-circuit state. All devices connected to the CAN bus, including terminating resistor 1, electronic control component 8, data acquisition tool 9, electronic control component 10, electronic control component 11, and terminating resistor 2, need to be disconnected one by one. When the resistance test value changes to around 60Ω or 120Ω after disconnecting a device, it indicates that the currently disconnected device is faulty. If the resistance test value remains around 0Ω after disconnecting all devices, it indicates that the main wiring harness 3 is faulty.

[0042] (d) If the resistance readings between the two points are different (e.g., 0Ω between A and a, and 120Ω between E and e), it indicates that the electronic control component 10 is faulty. If the resistance between A and a is still 0Ω after removing the electronic control component 10, it indicates that the circuit to the left of the electronic control component 10 is short-circuited.

[0043] Detecting transient bus faults: Some faults are not persistent and stable, but occur sporadically during communication. Therefore, after completing the (b) stable bus fault detection, it is necessary to power on the electronic control components 8, 9, 10, and 11 in the CAN bus 12 to enable them to send and receive messages normally. Under this premise, the voltage waveforms at 10 points A, B, C, H, J, D, E, F, G, and K are compared to determine whether one line of the CAN bus has a transient fault, and the voltage waveforms at another 10 points b, c, d, h, j, d, e, f, g, and k are compared to determine whether the other line of the CAN bus has a transient fault. The fault evaluation unit 15 will provide an evaluation result based on the tested voltage waveforms:

[0044] (a) If the voltage waveforms of 10 points A, B, C, H, J, D, E, F, G, K are consistent, and the voltage waveforms of another 10 points b, c, d, h, j, d, e, f, g, k are also consistent, then the fault display unit 16 indicates that there is no obvious transient fault on this CAN bus.

[0045] (b) If the voltage waveforms of the two furthest points (e.g., A and E, a and e) are consistent, it indicates that there is no fault in the bus harness 3 and the electrical control component 10.

[0046] (c) If the voltage waveforms of A, B, C or a, b, c are inconsistent, or the voltage waveforms of D, E or d, e are inconsistent, the fault assessment unit 15 indicates that the bus harness 3 is faulty.

[0047] (d) If there is a voltage waveform inconsistency between any two points: B and F or b and f, C and G or c and g, D and K or d and k, then the fault assessment unit 15 needs to indicate that the corresponding branch harness is faulty. For example, if the voltage waveforms of C and G are inconsistent, then the fault assessment unit 15 indicates that the connector of the branch harness 5 or the data acquisition tool 9 is faulty.

[0048] (f) If the voltage waveforms of C and H or c and h are inconsistent, or the voltage waveforms of J and D or j and d are inconsistent, the fault assessment unit 15 indicates that the daisy chain harness 6 is faulty.

[0049] (e) If the voltage waveforms of H and J or h and j are inconsistent, the fault assessment unit 15 indicates that the electronic control component 10 is faulty.

[0050] The following is for reference. Figure 3 , Figure 3 A schematic flowchart of a fault detection method 30 for a vehicle CAN bus according to an embodiment of this application is shown.

[0051] Fault detection method 30 includes: step S310, sampling the resistance of preset key points when all components on the CAN bus are de-energized; step S320, sampling the voltage of preset key points when all components on the CAN bus are energized and the electronic control components on the CAN bus are in communication mode; and step S330, determining the fault type and fault point based on the CAN bus topology, the sampled resistance, and the voltage. For example, step S330 specifically includes: detecting steady-state bus faults by comparing the sampled resistance with preset resistance values; and detecting transient bus faults by comparing the voltage waveforms at each preset key point.

[0052] Optionally, the fault detection method 30 also includes displaying the determined fault type and fault point on a screen in a visual manner.

[0053] Optionally, the preset key points include: the connection points between the main harness and the branch harness or daisy-chain harness of the CAN bus; and the connection points between each component and the main harness, branch harness or daisy-chain harness. Components on the CAN bus include: terminating resistors; electronic control components connected in parallel to the main harness via branch harnesses, and / or electronic control components connected in series to the main harness via daisy-chain harnesses.

[0054] According to a third aspect of this application, a computer-readable storage medium is provided, wherein instructions are stored therein, characterized in that, when executed by a processor, the instructions cause the processor to perform the following actions: Figure 3 The method described.

[0055] The foregoing disclosure is not intended to limit this disclosure to the precise form disclosed or any particular field of use. Therefore, it is contemplated that various alternative embodiments and / or modifications of this disclosure are possible, whether expressly described or implied herein. Given that embodiments of this disclosure have been described as such, those skilled in the art will recognize that changes in form and detail may be made without departing from the scope of this disclosure. Therefore, this disclosure is limited only by the claims.

Claims

1. A method for fault detection for a vehicle CAN bus, characterized in that, The method includes the following steps: When all components on the CAN bus are powered off, resistance sampling is performed on preset key points. The preset key points include: the connection points between the main line harness and the branch line harness or daisy chain harness of the CAN bus, and the connection points between each component and the main line harness, the branch line harness or the daisy chain harness. With all components on the CAN bus powered on and the electronic control components on the CAN bus in communication mode, voltage sampling is performed on the preset key points; and The fault type and fault location are determined based on the CAN bus topology, sampled resistors, and voltages, including: Steady-state bus faults are detected by comparing sampled resistance values ​​with preset resistance values; and Transient bus faults are detected by comparing voltage waveforms at various preset key points.

2. The method of claim 1, wherein, The method further includes: The identified fault types and fault locations are displayed on the screen in a visual manner.

3. The method according to claim 1, wherein, The components on the CAN bus include: Terminating resistor; Electrical control components connected in parallel to the main wire harness via the branch wire harness, and / or connected in series to the main wire harness via the daisy chain wire harness.

4. A failure detection device for a vehicle CAN bus, characterized by, The device includes: The fault sampling unit is configured as follows: When all components on the CAN bus are powered off, resistance sampling is performed on preset key points. The preset key points include: the connection points between the main line harness and the branch line harness or daisy chain harness of the CAN bus, and the connection points between each component and the main line harness, the branch line harness or the daisy chain harness. With all components on the CAN bus powered on and the electronic control components on the CAN bus in communication mode, voltage sampling is performed on the preset key points; and The fault assessment unit is configured as follows: The fault type and fault location are determined based on the CAN bus topology, sampled resistors, and voltages, including: Steady-state bus faults are detected by comparing sampled resistance values ​​with preset resistance values; and Transient bus faults are detected by comparing voltage waveforms at various preset key points.

5. The apparatus according to claim 4, wherein, The device further includes: The fault display unit is configured to display the identified fault type and fault location on the screen in a visual manner.

6. The apparatus according to claim 4, wherein, The components on the CAN bus include: Terminating resistor; Electrical control components connected in parallel to the main wire harness via the branch wire harness, and / or connected in series to the main wire harness via the daisy chain wire harness.

7. A computer-readable storage medium storing instructions, characterized in that, When the instruction is executed by the processor, it causes the processor to perform the method as described in any one of claims 1-3.

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