Vehicle self-diagnostic device

Abstract

To provide a vehicle self-diagnostic device capable of notifying when a vehicle speed of an own vehicle which is acquired based on a rotation speed per unit time of a wheel of the own vehicle, is inaccurate.SOLUTION: A vehicle self-diagnostic device comprises: a camera 22 which outputs information on an image obtained by photographing a predetermined region around an own vehicle; a millimeter-wave radar 23 which acquires and outputs a relative speed which is a speed of a three-dimensional object with respect to the own vehicle; and a vehicle speed sensor 21 which acquires and outputs a vehicle speed of the own vehicle based on a rotation speed N per unit time of a wheel of the own vehicle. The vehicle self-diagnostic device is configured to: identify a static object OB around the own vehicle based on the information output from the camera 22; acquire a relative speed vr which is a speed of the static object OB with respect to the own vehicle from the millimeter-wave radar 23; acquire an absolute value of a component in a direction parallel to a travel direction of the own vehicle as an actual speed vsa of the own vehicle; and provide a driver with predetermined information when duration of a state where the absolute value of a difference between the vehicle speed vs from the vehicle speed sensor 21 and the actual vehicle speed vsa exceeds a threshold exceeds a threshold.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a vehicle self-diagnosis device capable of notifying that the vehicle speed (absolute value) of a host vehicle obtained based on the number of rotations of the wheels of the host vehicle per unit time is inaccurate.

Background Art

[0002] A vehicle speed sensor for detecting the vehicle speed of a host vehicle is well-known (see, for example, Patent Document 1 below). This type of vehicle speed sensor acquires the number of rotations N of the wheels per unit time, and multiplies the number of rotations N by the dynamic load radius (coefficient k) of the wheels to acquire and output the vehicle speed vs of the host vehicle. This coefficient k is determined at the time of factory shipment of the vehicle (at the time of vehicle design) and is stored in the storage device (ROM) of the vehicle speed sensor. That is, the coefficient k is a fixed value (non-rewritable). In a conventional vehicle, the value (vehicle speed vs) output from the vehicle speed sensor may be displayed on a display (speedometer) provided on the instrument panel of the vehicle. Also, control (driving support, automatic driving) of the host vehicle may be executed based on the value (vehicle speed vs) output from the vehicle speed sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] Incidentally, the dynamic load radius of a wheel changes (expands or contracts) depending on the tire pressure. Also, the dynamic load radius may change if the user replaces the wheels on their vehicle. For example, if the outer diameter of the replacement wheel is larger than the outer diameter of the factory-installed wheel (i.e., the wheel size is increased), the dynamic load radius is likely to increase. However, as mentioned above, the coefficient k of the vehicle speed sensor is a fixed value. Therefore, due to changes in the dynamic load radius of the wheel, the difference (error) between the vehicle speed vs output from the vehicle speed sensor and the actual vehicle speed vsa may become relatively large.

[0005] One of the objectives of the present invention is to provide a vehicle self-diagnostic device that can notify that the vehicle speed obtained based on the number of rotations of the vehicle's wheels per unit time is inaccurate.

[0006] To solve the above problems, the vehicle self-diagnostic device (1) of the present invention is: A camera (22) outputs information about images obtained by photographing a predetermined area around the vehicle, A millimeter-wave radar (23) that acquires and outputs the relative velocity of a three-dimensional object relative to the vehicle, A vehicle speed sensor (21) acquires and outputs the vehicle speed (vs) based on the number of rotations (N) of the vehicle's wheels per unit time, A processor (10) controls a notification device (30) so that predetermined information is provided to the driver when the duration (Δt) of the state in which the absolute value of the difference between the vehicle speed and the vehicle speed (Δvs) exceeds a threshold (Δtth) exceeds a threshold (Δtth), based on information acquired from the camera, the relative speed (vr) of the stationary object relative to the vehicle speed (vsa) is obtained from the millimeter-wave radar, the absolute value of the component of the relative speed of the stationary object parallel to the direction of travel of the vehicle speed (vsa) is obtained, and the vehicle speed is further obtained from the vehicle speed sensor, and predetermined information is provided to the driver. It is equipped with.

[0007] In this specification, "velocity" is a concept (vector) that includes the direction in which an object is moving and its speed (absolute value). On the other hand, "vehicle speed" and "actual vehicle speed" refer to the speed (absolute value) of a vehicle and are concepts (scalars) that do not include the direction in which the vehicle is moving.

[0008] The absolute value (speed) of the component of the relative velocity (vector) between a three-dimensional object (stationary object) fixed to the ground and the vehicle, which is parallel to the direction of travel of the vehicle, coincides with the actual vehicle speed (absolute value). The processor of the vehicle self-diagnostic device according to the present invention identifies a stationary object based on information acquired from a camera, and based on information acquired from millimeter-wave radar, acquires the absolute value of the component of the relative velocity (vector), which is the speed of the stationary object as seen from the vehicle, which is parallel to the direction of travel of the vehicle, as the actual vehicle speed of the vehicle. As a result, the processor can acquire the actual vehicle speed of the vehicle with high accuracy using means other than the vehicle speed sensor. If the duration of the state in which the absolute value of the difference between the vehicle speed acquired from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds the threshold, it is highly likely that the current value of the dynamic load radius of the wheel is excessive or insufficient compared to the design value. In this case, the processor determines that the vehicle speed output from the vehicle speed sensor is inaccurate and provides the driver with predetermined information (information indicating that the output of the vehicle speed sensor is inaccurate). As described above, the vehicle self-diagnostic device according to the present invention can detect when the vehicle speed output from the vehicle speed sensor is inaccurate (has low reliability).

[0009] In a vehicle self-diagnostic device according to one aspect of the present invention, The processor performs a correction process to correct the vehicle speed output from the vehicle speed sensor based on the ratio of the actual vehicle speed to the vehicle speed obtained from the vehicle speed sensor, if the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold.

[0010] According to this, other ECUs in the vehicle (for example, an ECU that performs driver assistance, or an ECU that displays the vehicle speed on a display device on the instrument panel) can perform various processes based on the corrected vehicle speed (the accurate value).

[0011] In another aspect of the present invention, a vehicle self-diagnostic device, The processor executes the correction process when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle performs an operation requesting that the vehicle speed be corrected.

[0012] According to this, the driver can choose whether or not to correct the vehicle speed output from the vehicle speed sensor.

[0013] In another aspect of the present invention, a vehicle self-diagnostic device, The processor controls the notification device so that, if the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle does not perform an operation to request that the vehicle speed be corrected, the driver of the vehicle does not perform the correction process and information regarding the wheels of the vehicle is provided to the driver.

[0014] For example, the processor displays information (images) on the display device regarding how to measure and adjust the tire pressure and how to replace the tires, as information to prompt the vehicle to inspect the tires. The processor also displays information on the display device regarding repair shops that can replace the vehicle's tires. When the driver or a repair shop employee adjusts the tire pressure or replaces the tires, the dynamic load radius will approximately match the design value, and the vehicle speed sensor will output an accurate vehicle speed.

[0015] In another aspect of the present invention, a vehicle self-diagnostic device, The processor temporarily disables the driver assistance functions of the vehicle without performing the correction process if the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle does not perform an operation to request correction of the vehicle speed.

[0016] In some vehicles, the control unit (driver assistance ECU) is configured to perform driver assistance based on the vehicle speed output from the vehicle speed sensor. In such a vehicle, if the vehicle speed output from the vehicle speed sensor is inaccurate, there is a risk that the driver assistance will not be performed as intended by the designer. According to the present invention, if it is determined that the output from the vehicle speed sensor is inaccurate, the execution of driver assistance is prohibited. In other words, the provision of driver assistance that differs from the designer's intention is suppressed. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a block diagram of a vehicle self-diagnostic device according to one embodiment of the present invention. [Figure 2] Figure 2 is a plan view showing the process of acquiring the actual vehicle speed. [Figure 3] Figure 3 is a flowchart of the program executed by the CPU to implement the correction function. [Figure 4] Figure 4 is a flowchart of the program executed by the CPU to implement the diagnostic function and the correction coefficient update function. [Modes for carrying out the invention]

[0018] (Summary) As shown in Figure 1, the vehicle self-diagnostic device 1 according to one embodiment of the present invention is applied to a vehicle V equipped with an autonomous driving function (hereinafter referred to as "the vehicle"). The vehicle self-diagnostic device 1 has a function (diagnostic function) that detects and notifies when the vehicle speed vs of the vehicle output from the vehicle speed sensor 21, which will be described later, is inaccurate, and a function (correction function) that corrects the vehicle speed vs when it is inaccurate.

[0019] (Specific configuration) As shown in FIG. 1, the vehicle self-diagnosis device 1 includes an ECU 10, an in-vehicle sensor 20, a notification device 30, and an operation switch 40.

[0020] The ECU 10 includes a microcomputer including a CPU 10a, a ROM 10b (rewritable non-volatile memory), a RAM 10c, a timer 10d, etc. The CPU realizes various functions by executing a program (instruction) stored in the ROM. The ECU 10 is connected via a CAN (Controller Area Network) to other ECUs (for example, an ECU that executes driving support, an ECU that causes a display device provided on an instrument panel to display various parameters (for example, the vehicle speed of the host vehicle, the engine speed, etc.)).

[0021] The in-vehicle sensor 20 includes a vehicle speed sensor 21, a camera 22, and a millimeter-wave radar 23.

[0022] The vehicle speed sensor 21 includes a rotation speed measurement circuit and a vehicle speed calculation device. The rotation speed measurement circuit includes a pulse generation circuit that outputs a pulse (electrical signal) every time the wheels of the host vehicle rotate by a predetermined angle, and a counter circuit that counts the number of the pulses. The vehicle speed calculation device acquires the output value (number of pulses) of the counter circuit at a predetermined period (every time a unit time elapses), and resets the count value to "0". In this way, the vehicle speed calculation device acquires the rotation speed N of the wheels per unit time. Then, the vehicle speed calculation device acquires the vehicle speed vs (absolute value) of the host vehicle by multiplying the rotation speed N by a coefficient k. The coefficient k is stored in the ROM included in the vehicle speed calculation device. That is, the coefficient k is a fixed value. The vehicle speed sensor 21 provides the vehicle speed vs to the ECU 10.

[0023] Camera 22 is equipped with an imaging device and an image analysis device. The imaging device incorporates, for example, a CCD. The imaging device is installed at the front of the vehicle and directed forward. The imaging device captures the foreground of the vehicle at a predetermined frame rate and acquires image data. The image analysis device acquires image data from the imaging device, analyzes the image data to recognize (identify) objects present within the field of view, and can acquire the position (relative position) of the objects relative to the vehicle based on the position (coordinates) of the objects in the image. For example, the image analysis device recognizes (identifies) a three-dimensional object (a stationary object OB (e.g., a traffic sign)) installed (fixed) on the ground and acquires its position P (the position of the stationary object relative to the vehicle). The image analysis device provides the recognition result (object identification result and the position of the object relative to the vehicle) to the ECU 10.

[0024] The millimeter-wave radar 23 includes a transmitting / receiving unit and a signal processing unit (not shown). The transmitting / receiving unit radiates millimeter-wave radio waves (hereinafter referred to as "millimeter waves") in front of the vehicle and receives millimeter waves (reflected waves) reflected by three-dimensional objects located within the radiation range. The signal processing unit acquires various information about each reflection point R of the millimeter waves based on physical quantities such as the time from when the transmitting / receiving unit radiates the millimeter waves until the reflected waves are received, the attenuation level of the reflected waves, and the difference between the frequency of the radiated millimeter waves and the frequency of the received reflected waves. For example, the signal processing unit calculates the position of each reflection point R (position RP (direction and distance) relative to the transmitting / receiving unit). The signal processing unit also calculates the relative velocity vr (vector), which is the velocity of each reflection point R relative to the vehicle. The unit then transmits the calculation results (data showing the distribution of reflection points R (data including the position RP and relative velocity vr of each reflection point R)) to the ECU 10. Furthermore, the range in which the millimeter-wave radar 23 can detect three-dimensional objects (the range in which millimeter waves are emitted) is approximately the same as the field of view (imaging range) of the camera 22.

[0025] The notification device 30 includes an image display device and an audio device. The image display device receives an image display command from the ECU 10 and displays a predetermined image according to the command. The audio device also receives an audio playback command from the ECU 10 and plays a predetermined sound according to the command.

[0026] The operation switch 40 includes a first switch 41 operated when the driver requests to start a vehicle speed diagnosis, as described later, and a second switch 42 operated when the driver requests to update the correction coefficient Δk. These switches are configured, for example, as push-button type switch devices. These switches are incorporated, for example, into the spokes of the steering wheel. The ECU 10 monitors the on / off state of these switches.

[0027] (Correction function) When the ignition switch is ON, the ECU 10 acquires the vehicle speed vs from the vehicle speed sensor 21 at a predetermined interval, multiplies the vehicle speed vs by a correction coefficient Δk, and provides the resulting vehicle speed vs to other ECUs (for example, an ECU that performs driving assistance such as ACC (=Adaptive cruise control), or an ECU that displays the vehicle speed on the instrument panel display device). Here, when the vehicle is delivered from the factory (i.e., when the dynamic load radius of the wheels matches the design value or the error is small), the correction coefficient Δk is initialized to "1". As will be described later, the correction coefficient Δk is updated when a predetermined operation is performed. The correction coefficient Δk is stored in the ROM 10b (flash ROM). Therefore, even if the ignition switch is turned OFF, the correction coefficient Δk is retained.

[0028] (Diagnostic function) When the ECU 10 detects that the first switch 41 has been pressed, it acquires various information (information about the identified target and information about the reflection point R) from the camera 22 and the millimeter-wave radar 23 at a predetermined interval. Generally, a camera image analysis device can accurately identify each target (other vehicles, guardrails, signs, etc.) included in an image based on the image data acquired from the imaging device. However, the image recognition device cannot accurately acquire the speed of each target (speed relative to the vehicle (relative speed vr)). In contrast, the signal processing unit of the millimeter-wave radar can accurately acquire the speed of each target (speed of the target relative to the vehicle (relative speed vr)). However, the signal processing unit cannot accurately identify each target. In this embodiment, the ECU 10 identifies (selects) a stationary object OB based on the information acquired from the camera 22, and acquires the speed of the stationary object OB relative to the vehicle (relative speed vr) based on the information acquired from the millimeter-wave radar 23 (fusion processing).

[0029] Specifically, the ECU 10 associates a traffic sign (in this embodiment, a sign indicating a speed limit) as a stationary object OB (a predetermined type of object usually fixed to the ground) among the targets identified by the image recognition device of the camera 22 with a reflection point R corresponding to the stationary object OB. For example, the ECU 10 obtains the position P of the selected stationary object OB from the camera 22. The ECU 10 then selects a plurality of reflection points R from the reflection points R obtained from the millimeter-wave radar 23 that are at the same position as or at a distance below a threshold from position P (the position of the stationary object OB obtained from the image recognition device), and that the set of these reflection points (reflection point group) is distributed in a substantially circular shape (the shape of the sign indicating a speed limit). The ECU 10 then selects the reflection point Rc located at the center of the plurality of reflection points R selected above. The ECU 10 obtains the relative velocity vr of the reflection point Rc from the signal processing device of the millimeter-wave radar 23 (see Figure 2). The map M shown in Figure 2 is an XY coordinate plane with the origin O at the center of the vehicle's front end in the vehicle width direction in a plan view. Its X-axis coincides with the vehicle's longitudinal direction, and its Y-axis coincides with the vehicle's width direction. In the following explanation, the angle between the line connecting the origin O and the reflection point Rc and the X-axis will be referred to as "angle θ".

[0030] Here, the absolute value of the X-axis component of the relative velocity vr matches the actual vehicle speed vsa. The ECU10 obtains the actual vehicle speed vsa based on the following calculation formula (1). vsa = |vr| × cosθ ···(1)

[0031] Furthermore, if the information acquired from the camera 22 includes information about multiple stationary objects OB, the ECU 10 selects one of them. For example, the ECU 10 selects the stationary object OB closest to its own vehicle. However, the ECU 10 may also select multiple stationary objects OB, calculate the actual vehicle speed vsa based on the relative velocity vr of each stationary object OB, and adopt the average of these multiple actual vehicle speeds vsa as the actual vehicle speed vsa.

[0032] Next, the ECU 10 obtains the vehicle speed vs from the vehicle speed sensor 21. The ECU 10 calculates the absolute difference (error Δvs) between the absolute value of the vehicle speed vs and the actual vehicle speed vsa. Next, the ECU 10 determines whether the error Δvs exceeds the threshold Δvsth. The ECU 10 uses timer 10d to measure the time Δt during which the state in which the error Δvs exceeds the threshold Δvsth (Δvs > Δvsth) continues. If the time Δt exceeds the threshold Δtth, the ECU 10 determines that there is a high probability that the current dynamic load radius of the wheel is excessive or insufficient compared to the design value. In other words, the ECU 10 determines that the output of the vehicle speed sensor 21 is inaccurate. In this case, the ECU 10 displays an image indicating that "vehicle speed vs is inaccurate" on the image display device of the notification device 30, and plays a predetermined sound (beep) on the sound device.

[0033] On the other hand, if the error Δvs is less than or equal to the threshold Δvsth, the ECU 10 determines that the current dynamic load radius of the wheel is likely to match the design value. In other words, the ECU 10 determines that the output of the vehicle speed sensor 21 is accurate. In this case, the ECU 10 displays an image indicating that "the output of the vehicle speed sensor is accurate" on the image display device of the notification device 30, and plays a predetermined sound on the sound device. Furthermore, if the error Δvs exceeds the threshold Δvsth, but before time Δt reaches the threshold Δtth, it is highly likely that the dynamic load radius of the wheel has temporarily (for a short time only) fluctuated (increased or decreased relative to the design value). In this case as well, the ECU 10 displays information (image and sound) indicating that "the output of the vehicle speed sensor is accurate" on the notification device 30.

[0034] (Correction coefficient update function) As described above, after the ECU 10 notifies that the output of the vehicle speed sensor 21 (vehicle speed vs) is inaccurate, it displays an image on the image display device and plays a predetermined sound on the sound device to perform an operation to approve updating the correction coefficient Δk (update confirmation process). If the ECU 10 detects that the second switch 42 has been pressed within a predetermined time after the time ts in which the above update confirmation process was performed, it acquires (updates) the correction coefficient Δk based on the following calculation formula (2). Δk = vsa / vs ... (2)

[0035] If the second switch 42 is not pressed within a predetermined time after time ts, the ECU 10 disables a predetermined driver assistance function (a function that controls the vehicle based on vehicle speed vs) provided by the vehicle. In this case, the ECU 10 causes the image display device of the notification device 30 to display an image indicating that the predetermined driver assistance function has been disabled.

[0036] Next, referring to Figure 3, we will explain the program PR1 executed by CPU 10a (hereinafter simply referred to as "CPU") to realize the above correction function. Furthermore, referring to Figure 4, we will explain the program PR2 executed by the CPU to realize the above diagnostic function and correction coefficient update function.

[0037] (Program PR1) The CPU executes program PR1 at predetermined intervals when the ignition switch is ON. The CPU starts executing program PR1 from step 100 and proceeds to step 101.

[0038] In step 101, the CPU obtains the vehicle speed vs from the vehicle speed sensor 21. Next, the CPU proceeds to step 102.

[0039] In step 102, the CPU corrects the vehicle speed vs. Specifically, the CPU obtains the accurate vehicle speed vs. (corrected vehicle speed vs.) by multiplying the vehicle speed vs. by a correction coefficient Δk. Next, the CPU proceeds to step 103. The correction coefficient Δk is initialized to "1" at the factory. Furthermore, as will be described later, the correction coefficient Δk may be updated after the factory shipment during the process of the CPU executing program PR2.

[0040] In step 103, the CPU provides the corrected vehicle speed vs to the other ECUs. Next, the CPU proceeds to step 104, in which step 104, the execution of program PR1 is terminated.

[0041] (Program PR2) When the CPU detects that the first switch 41 has been pressed, it starts executing program PR2 from step 200 and also starts measuring time Δt with timer 10d. Next, the CPU proceeds to step 201.

[0042] In step 201, the CPU obtains the vehicle speed (vs) from the vehicle speed sensor 21. Next, the CPU proceeds to step 202.

[0043] In step 202, the CPU obtains the actual vehicle speed vsa (=|vr|×cosθ) based on various information acquired from the camera 22 and the millimeter-wave radar 23. Next, the CPU proceeds to step 203.

[0044] In step 203, the CPU determines whether the error Δvs, which is the absolute value of the difference between the actual vehicle speed vsa and the vehicle speed vs, exceeds the threshold Δvsth. If the CPU determines that the error Δvs exceeds the threshold Δvsth (203: Yes), it proceeds to step 204. On the other hand, if the CPU does not determine that the error Δvs exceeds the threshold Δvsth (203: No), it proceeds to step 206.

[0045] In step 204, the CPU determines whether time Δt (the duration of the state in which the error Δvs exceeds the threshold Δvsth) exceeds the threshold Δtth. If the CPU determines that time Δt exceeds the threshold Δtth (204: Yes), it proceeds to step 205. On the other hand, if the CPU does not determine that time Δt exceeds the threshold Δtth (204: No), it returns to step 201.

[0046] In step 205, the CPU displays an image on the image display device indicating that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, and plays a predetermined sound on the sound device. Next, the CPU proceeds to step 207.

[0047] In step 206, the CPU displays an image on the display device indicating that the vehicle speed vs output from the vehicle speed sensor 21 is accurate, and plays a predetermined sound on the sound device. Next, the CPU proceeds to step 210, in which step 210 terminates the execution of program PR2.

[0048] In step 207, the CPU displays an image on an image display device to initiate the operation to update the correction coefficient Δk, plays a predetermined sound on an audio device, and then determines whether the second switch 42 was pressed within a predetermined time. If the CPU determines that the second switch 42 was pressed within the predetermined time (207: Yes), it proceeds to step 208. On the other hand, if the CPU does not determine that the second switch 42 was pressed within the predetermined time (207: No), it proceeds to step 209.

[0049] In step 208, the CPU updates the correction coefficient Δk (=vsa / vs). Then, the CPU proceeds to step 210 and finishes executing program PR2.

[0050] In step 209, the CPU disables the specified driver assistance function (prohibits the execution of driver assistance). Next, the CPU proceeds to step 210 and terminates the execution of program PR2.

[0051] (effect) The absolute value of the component of the relative velocity (vector) between a fixed three-dimensional object (stationary object OB) on the ground and the vehicle, which is parallel to the direction of travel of the vehicle, corresponds to the actual vehicle speed. The ECU 10 identifies the stationary object OB based on the information acquired from the camera 22. The ECU 10 also acquires the relative velocity vr between the stationary object OB and the vehicle from the millimeter-wave radar 23. The ECU 10 then acquires the absolute value of the X-axis component of the relative velocity vr as the actual vehicle speed vsa. This allows the ECU 10 to acquire the actual vehicle speed vsa with high accuracy using a means other than the vehicle speed sensor 21. If the duration Δt of the state in which the error Δvs, which is the absolute value of the difference between the vehicle speed vs acquired from the vehicle speed sensor 21 and the actual vehicle speed vsa, exceeds the threshold Δvsth exceeds the threshold Δtth, it is determined that there is a high possibility that the current dynamic load radius of the wheel is excessive or insufficient compared to the design value. In other words, the ECU 10 determines that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate and causes the notification device 30 to display predetermined information (information indicating that the output from the vehicle speed sensor 21 is inaccurate). As described above, the vehicle self-diagnostic device 1 can detect that the vehicle speed vs output from the vehicle speed sensor 21 of the vehicle is inaccurate.

[0052] Furthermore, if the ECU 10 determines that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, and the driver requests that the correction coefficient Δk be updated, the ECU 10 updates the correction coefficient Δk. Subsequently, the ECU 10 corrects the vehicle speed vs obtained from the vehicle speed sensor 21 using the updated correction coefficient Δk. The ECU 10 then provides the corrected vehicle speed vs to other ECUs. Other ECUs in the vehicle (for example, an ECU that performs driver assistance, an ECU that displays the vehicle speed on a display device on the instrument panel, etc.) can perform various processes based on the corrected vehicle speed vs (the accurate value).

[0053] Furthermore, if the driver assistance ECU of the vehicle is configured to perform driver assistance (e.g., ACC) based on the vehicle speed vs output from the vehicle speed sensor 21, and the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate, there is a risk that the driver assistance (ACC) will not be performed as intended by the designer. In this embodiment, the ECU 10 of the vehicle self-diagnostic device 1 disables the driver assistance function (ACC) if it determines that the vehicle speed vs output from the vehicle speed sensor 21 is inaccurate and does not request that the correction coefficient Δk be updated. This prevents the provision of driver assistance (ACC) that differs from the designer's intention.

[0054] The present invention is not limited to the embodiments described above, and various modifications can be adopted within the scope of the present invention, as described below.

[0055] <Example 1> The vehicle self-diagnostic device 1 may have only the diagnostic function described above, and the correction function and correction coefficient update function may be omitted.

[0056] <Modification 2> The vehicle self-diagnostic device 1 may include a device for detecting whether or not a wheel (tire) has been replaced. In this case, the ECU 10 should automatically start executing program PR2 when it detects that a wheel has been replaced.

[0057] <Variation 3> If the ECU 10 determines that the vehicle speed vs is inaccurate, it may display an image on a display device for the driver to choose whether or not they have changed the wheels (tires). If the driver selects "changed the wheels (tires)" using a predetermined operating device, the ECU 10 updates the correction coefficient Δk.

[0058] <Modification 4> If the second switch 42 is not pressed within a predetermined time from time ts, the ECU 10 may display information about the wheels on the display device. For example, if the vehicle speed vs is greater than the actual vehicle speed vsa, the ECU 10 may display an image on the image display device indicating that the tire pressure may be too high. Conversely, if the vehicle speed vs is less than the actual vehicle speed vsa, the ECU 10 may display an image on the image display device indicating that the tire pressure may be too low. Also, for example, the ECU 10 may display information (images) on the display device regarding how to measure and adjust the tire pressure and how to replace the wheels, as information to encourage the inspection of the wheels. The ECU 10 may also display information on the display device regarding repair shops that can replace the wheels of the vehicle. By adjusting the tire pressure or replacing the wheels, the dynamic load radius will approximate the design value, and the vehicle speed sensor 21 will output an accurate vehicle speed vs. If the driver assistance function is disabled, after completing the above-mentioned wheel repair, the disabled driver assistance function will be reactivated by performing a predetermined operation (sending a predetermined command to the ECU10 from an external device). [Explanation of symbols]

[0059] 1... Vehicle self-diagnostic device, 10... ECU, 20... On-board sensor, 30... Notification device

Claims

1. A camera that outputs information about images obtained by photographing a predetermined area around the vehicle, A millimeter-wave radar that acquires and outputs the relative velocity of a three-dimensional object relative to the vehicle itself, A vehicle speed sensor that acquires and outputs the vehicle speed based on the number of rotations of the vehicle's wheels per unit time, A processor that, based on information acquired from the camera, identifies stationary objects around the vehicle, acquires the relative speed of the stationary objects relative to the vehicle from the millimeter-wave radar, acquires the absolute value of the component of the relative speed of the stationary objects that is parallel to the direction of travel of the vehicle as the actual vehicle speed, and further acquires the vehicle speed from the vehicle speed sensor, and controls the notification device so that predetermined information is provided to the driver when the duration of the state in which the absolute value of the difference between the vehicle speed and the actual vehicle speed exceeds a threshold exceeds a threshold, A vehicle self-diagnostic device equipped with the following features.

2. In the vehicle self-diagnostic device according to claim 1, The aforementioned processor is a vehicle self-diagnostic device that, when the duration of a state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, performs a correction process to correct the vehicle speed output from the vehicle speed sensor based on the ratio of the actual vehicle speed and the vehicle speed obtained from the vehicle speed sensor.

3. In the vehicle self-diagnostic device according to claim 2, The processor is a vehicle self-diagnostic device that performs the correction process when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle performs an operation requesting that the vehicle speed be corrected.

4. In the vehicle self-diagnostic device according to claim 2, A vehicle self-diagnostic device, wherein the processor controls the notification device so that, if the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle does not perform an operation to request the correction of the vehicle speed, the driver of the vehicle will be provided with information about the wheels of the vehicle without performing the correction process.

5. In the vehicle self-diagnostic device according to claim 2, The processor is a vehicle self-diagnostic device that, when the duration of the state in which the absolute value of the difference between the vehicle speed obtained from the vehicle speed sensor and the actual vehicle speed exceeds a threshold exceeds a threshold, and the driver of the vehicle does not perform an operation to request correction of the vehicle speed, temporarily disables the driver assistance functions of the vehicle without performing the correction process.

Images