Failure determination method and failure determination apparatus

Abstract

To determine where a failure occurred among multiple displacement sensors in a case where an abnormality occurred in outputs of the displacement sensors in detecting displacements in multiple spots on a vehicle body using the displacement sensors.SOLUTION: A failure determination method includes: detecting respective displacements of positions of at least four different points forming approximately one plane on a vehicle body using multiple displacement sensors (S1); computing, in a case where a distortion of the one plane is assumed to be zero on the basis of output results of the multiple displacement sensors, displacements to be output from the multiple displacement sensors respectively (S2, S3); and determining, in a case where a difference between an output of any of the multiple displacement sensors and the computed displacement is equal to or larger than a threshold, that there is a failure in any of a displacement sensor among the multiple displacement sensors, a mounting component where any displacement senor is mounted on the vehicle, and a vehicular component on which any displacement sensor is mounted (S4, S5).SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a failure determination method and a failure determination device. [Background technology]

[0002] The following Patent Document 1 describes an abnormality determination device that, when a vehicle is traveling straight ahead, integrates the outputs of front and rear stroke sensors that detect the strokes of the front and rear wheels relative to the vehicle body over a predetermined time period, and determines an abnormality when the deviation between the calculated front and rear integrated values ​​is equal to or greater than a threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-015633 Summary of the Invention [Problem to be solved by the invention]

[0004] When an abnormality occurs in the output of the stroke sensor, the abnormality determination device of Patent Document 1 cannot identify whether the failure has occurred in the front wheel or the rear wheel. The present invention aims to determine which of multiple locations on a vehicle body has failed when an abnormality occurs in the output of a displacement sensor when the displacements at multiple locations on the vehicle body are detected by multiple displacement sensors. [Means for solving the problem]

[0005] In one aspect of the fault determination method of the present invention, a plurality of displacement sensors detect displacements at at least four positions on a vehicle body that are approximately on the same plane, and based on the output results of the plurality of displacement sensors, calculate the displacement that each of the plurality of displacement sensors should output if it is assumed that the amount of distortion of the same plane is zero.If the difference between the output result of any of the plurality of displacement sensors and the calculated displacement is equal to or greater than a threshold, it is determined that any of the plurality of displacement sensors, an attachment part that attaches any of the displacement sensors to the vehicle, or a component of the vehicle to which any of the displacement sensors is attached by an attachment part has failed. [Effects of the Invention]

[0006] According to the present invention, when detecting displacements at multiple locations on a vehicle body using multiple displacement sensors, if an abnormality occurs in the output of a displacement sensor, it is possible to determine which of these multiple locations has failed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an example of a vehicle equipped with a displacement detection device as an embodiment of a failure determination device; [Figure 2] FIG. 1 is a diagram illustrating an example of a configuration of a suspension device. [Figure 3] 1(a) and 1(b) are explanatory diagrams of a displacement sensor. [Figure 4] FIG. 2 is a block diagram showing an example of a functional configuration of a suspension controller according to the first embodiment. [Figure 5] 3 is a flowchart illustrating an example of a failure determination method according to the first embodiment. [Figure 6] FIG. 10 is a block diagram showing an example of a functional configuration of a suspension controller according to a second embodiment. [Figure 7] 10 is a flowchart illustrating an example of a failure determination method according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the drawings are schematic and may differ from the actual product. Furthermore, the embodiments of the present invention shown below are examples of devices and methods for embodying the technical concept of the present invention, and the technical concept of the present invention does not limit the structure, arrangement, etc. of component parts to those described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims.

[0009] (First embodiment) (composition) 1 is a schematic diagram of an example of a vehicle 1 equipped with a displacement detection device 10 as an embodiment of a failure determination device. The vehicle 1 is equipped with the displacement detection device 10 and an automatic braking device 20. The displacement detection device 10 detects the vertical (height) displacement of a predetermined position on the body of the vehicle 1. For example, the displacement detection device 10 may detect a wheel stroke, which is the vertical displacement of the wheel center of a wheel relative to the body of the vehicle 1, as the displacement of the predetermined position on the body. The displacement detection device 10 includes displacement sensors 11FR, 11RL, 11RR, and 11RL, and a suspension controller 12.

[0010] The displacement sensors 11FL, 11FR, 11RL, and 11RR are height sensors (stroke sensors) that detect the wheel strokes, which are the vertical displacements of the wheel centers of the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR of the vehicle 1 relative to the vehicle body. The displacement sensors 11FL, 11FR, 11RL, and 11RR output sensor signals ZFL, ZFR, ZRL, and ZRR, which are electrical signals corresponding to the detected wheel strokes, to the suspension controller 12.

[0011] In the following description, the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR of the vehicle 1 may be collectively referred to as "wheels 2." Furthermore, the displacement sensors 11FL, 11FR, 11RL, and 11RR may be collectively referred to as "displacement sensor 11," and the sensor signals ZFL, ZFR, ZRL, and ZRR may be collectively referred to as "sensor signal Z."

[0012] An example of a displacement sensor 11 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of a suspension device Sus that suspends a wheel 2 of a vehicle 1. The suspension device Sus includes an upper arm 4 and a lower arm 5 that support a knuckle 3 of the wheel 2 on a vehicle body 6 so that the knuckle 3 can move up and down, and a damper 7 and a spring 8 that connect the lower arm 5 to the vehicle body 6. The sensor body 11b of the displacement sensor 11 is attached to the body frame of the vehicle body 6 by a bracket 30, and a shaft 31 is connected to the tip of an arm 11a that is pivotally attached to the displacement sensor 11. The shaft 31 is connected to a bracket 32 ​​that is fixed to the upper arm 4.

[0013] Therefore, when the wheel center of the wheel 2 displaces up and down relative to the vehicle body 6, causing the upper arm 4 to swing as indicated by arrow 40, the arm 11a pivots in conjunction with this as indicated by arrow 41, with the mounting shaft that attaches the arm 11a to the sensor main body 11b as the axis of rotation. The displacement sensor 11 detects the arm angle θ, which is the angle of the arm 11a relative to the sensor main body 11b, and outputs a sensor signal Z having a value corresponding to the arm angle θ.

[0014] The brackets 30 and 32 and the shaft 31 are an example of "mounting parts that mount the displacement sensor to the vehicle" as set forth in the claims. The body frame of the vehicle body 6 to which the sensor main body 11b is attached and the upper arm 4 connected to the arm portion 11a are an example of "components of the vehicle to which the displacement sensor is attached by mounting parts" as set forth in the claims. In the following description, the mounting parts that mount the displacement sensor 11 to the vehicle 1 may be simply referred to as "mounting parts," and the components of the vehicle 1 to which the displacement sensor 11 is attached may be simply referred to as "components." Note that the bracket 32 ​​may be fixed to the lower arm 5 instead of the upper arm 4.

[0015] The mounting positions of the sensor bodies 11b of the displacement sensors 11FL, 11FR, 11RL, and 11RR are determined to be substantially on the same plane (to be located within the same plane). In other words, the displacement sensors 11FL, 11FR, 11RL, and 11RR detect vertical displacements at four positions on the same plane where these displacement sensors 11 are mounted. Note that "substantially on the same plane" does not mean that the mounting positions of the displacement sensors 11 are located strictly within the same plane, but is intended to allow for errors due to variations in the vehicle 1 and mounting. For example, "substantially on the same plane" may have an error of about 1 cm in the direction perpendicular to the plane relative to the exact plane. In the following description, the substantially same plane on which the sensor bodies 11b of the displacement sensors 11FL, 11FR, 11RL, and 11RR are attached may be referred to as the "mounting plane." Note that the description of this embodiment does not intend to limit the number of displacement sensors 11 to four. The number of displacement sensors 11 may be five or more, and vertical displacements at five positions within the mounting plane may be detected.

[0016] Furthermore, the displacement sensor 11 has a failure detection function. For example, the displacement sensor 11 may have a power supply failure detection function that detects a failure in the power supply that supplies power to the displacement sensor 11 or a failure in the harness that supplies power from the power supply to electrical components, and may detect that the power supply voltage has fallen outside a predetermined allowable range as a power supply failure or harness failure. Also, for example, the displacement sensor 11 may detect an offset of the sensor signal Z with respect to the actual arm angle θ as an offset failure. The displacement sensor 11 outputs a sensor failure signal Sf to the suspension controller 12, which indicates the result of detection of a power supply failure, harness failure, or offset failure by the displacement sensor 11.

[0017] See FIG. 1. The suspension controller 12 is an electronic control unit (ECU) that measures the wheel strokes of the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR based on the sensor signal Z from the displacement sensor 11. The suspension controller 12 includes a processor 13 and peripheral components such as a storage device 14. The processor 13 may be, for example, a CPU or an MPU. The storage device 14 may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 14 may include memories such as a register, a cache memory, and a ROM and RAM used as a main storage device. The functions of the suspension controller 12 described below are realized, for example, by the processor 13 executing a computer program stored in the storage device 14. Note that the suspension controller 12 may also be formed by dedicated hardware for executing the information processing described below. For example, the suspension controller 12 may include a functional logic circuit (such as a PLD, such as an FPGA) configured in a general-purpose semiconductor integrated circuit.

[0018] The suspension controller 12 outputs the measured wheel stroke to the automatic braking controller 23 of the automatic braking device 20. Furthermore, the suspension controller 12 determines whether or not there is a failure in the displacement sensor 11, the attached parts, or the components, based on the sensor signal Z and the sensor failure signal Sf of the displacement sensor 11. The suspension controller 12 outputs the results of the determination of the presence or absence of these failures to the automatic braking controller 23.

[0019] The automatic braking device 20 measures the distance between the vehicle 1 and an obstacle ahead of the vehicle 1 (for example, the distance between the vehicle 1 and a preceding vehicle), and automatically applies the brakes of the vehicle 1 when the distance becomes less than a predetermined threshold. The automatic braking device 20 includes a camera 21, a distance measuring device 22, an automatic braking controller 23, and a brake actuator 24. The camera 21 generates a captured image of the area ahead of the vehicle 1 and outputs it to the automatic braking controller 23. The distance measuring device 22 measures the position of an obstacle ahead of the vehicle 1 and outputs the measurement result to the automatic braking controller 23. For example, the distance measuring device 22 may be a laser range finder, radar, LiDAR (Light Detection and Ranging), sonar, or the like. The brake actuator 24 activates the brakes in response to a control signal from the automatic braking controller 23.

[0020] The automatic braking controller 23 is an electronic control unit (ECU) that automatically applies braking force to the brakes of the vehicle 1 based on the image captured by the camera 21, the measurement results from the distance measuring device 22, and the wheel stroke measured by the suspension controller 12. The automatic braking controller 23 includes a processor 25 and peripheral components such as a storage device 26. The processor 25 may be, for example, a CPU or an MPU. The storage device 26 may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 26 may include memories such as a register, a cache memory, and a ROM and RAM used as a main storage device. The functions of the automatic braking controller 23 described below are realized, for example, by the processor 25 executing a computer program stored in the storage device 26. The automatic braking controller 23 may also be formed by dedicated hardware for executing the information processing described below. For example, the automatic braking controller 23 may include a functional logic circuit (such as a PLD, such as an FPGA) configured in a general-purpose semiconductor integrated circuit.

[0021] The automatic braking controller 23 calculates the distance between the vehicle 1 and an obstacle ahead of the vehicle 1 based on the image captured by the camera 21 and the measurement results by the distance measuring device 22. The automatic braking controller 23 also corrects the calculated distance based on the wheel stroke measured by the suspension controller 12. If the corrected distance is shorter than a threshold value set according to the vehicle speed, the automatic braking controller 23 drives the brake actuator 24 to activate the brake device.

[0022] Here, if the error in the wheel stroke measured by the suspension controller 12 exceeds an allowable value, the automatic braking controller 23 may erroneously activate the brake device, causing the host vehicle 1 to come too close to the following vehicle. Therefore, if the suspension controller 12 detects a failure in the displacement sensor 11, an attached part, or a component part, the automatic braking controller 23 notifies the occupant of the failure and disables the automatic braking function based on the distance from an obstacle ahead.

[0023] Next, we will explain the process of determining whether there is a failure in the displacement sensor 11, attached parts, or component parts in the suspension controller 12. Fig. 3(a) is an example of a characteristics diagram showing the output characteristics of the sensor signal Z versus the arm angle θ of the arm 11a of the displacement sensor 11, and Fig. 3(b) is an example of a characteristics diagram showing the output characteristics of the sensor signal Z versus the actual wheel stroke. It is assumed that the upper and lower limit values ​​of the sensor signal Z that can be output by the displacement sensor 11 are "Z1" and "Z2," respectively. It is also assumed that the displacement sensor 11 outputs the upper limit value Z1 and the lower limit value Z2 when the arm angle θ is "θ1" and "θ2."

[0024] The upper limit of the possible wheel stroke (range of motion Rss) determined by the mechanical constraints of the suspension device Sus is defined as "Sta," and the lower limit as "Stb." The displacement sensor 11 is installed so that when the actual wheel stroke is at the upper limit Sta, the arm angle θ becomes angle θa (<θ1), outputting a sensor signal Za, and when the actual wheel stroke is at the lower limit Stb, the arm angle θ becomes angle θb (>θ2), outputting a sensor signal Zb. Therefore, the normal output range Rn of the sensor signal Z is Za to Zb, as shown by the dashed line in Figure 3(a).

[0025] Therefore, when the value of the sensor signal Z is in abnormal ranges R1, R2 outside the normal range Rn, a failure of the displacement sensor 11 itself can be detected from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, ZRR. However, even if some kind of fault has occurred, if the value of the sensor signal Z is within the normal range Rn, the fault cannot be detected from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, and ZRR. For example, if an abnormality occurs due to a fault in the output characteristics of the sensor signal Z relative to the actual wheel stroke (Figure 3(b)), the fault may not be detectable from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, and ZRR.

[0026] For example, if the mounting parts that attach the displacement sensor 11 to the vehicle 1 or the components of the vehicle 1 to which the displacement sensor 11 is attached by the mounting parts malfunction (e.g., break or deform), an abnormality may occur in the output characteristics of the sensor signal Z relative to the actual wheel stroke. The solid line Cn is the characteristic line when the output characteristics of the sensor signal Z relative to the actual wheel stroke are normal, and the two-dot chain line Ca is the characteristic line when the output characteristics are abnormal. When the actual wheel stroke is "St3," if the output characteristics of the sensor signal Z are normal, the displacement sensor 11 outputs a sensor signal Z3 (circular plot), whereas if the output characteristics are abnormal, it outputs a sensor signal Zx that differs from the appropriate value Z3 (triangle plot). However, because the sensor signal Zx is within the normal range Rn, a fault cannot be detected from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, and ZRR.

[0027] Therefore, the suspension controller 12 determines in which of the displacement sensors 11FL, 11FR, 11RL, and 11RR the failure of the displacement sensor 11 itself or the failure of an attached part or component has occurred. At this time, the suspension controller 12 calculates the mode components of the behavior of the mounting plane (i.e., the mode components of the vehicle body behavior of the vehicle body 6) based on the sensor signal Z. For example, the suspension controller 12 calculates the bounce component Z as the mode components of the behavior of the mounting plane. B , roll component Z R and pitch component Z P The components including

[0028] Based on these mode components and the sensor signal Z, the suspension controller 12 estimates the error component e contained in the sensor signal Z for each of the sensor signals ZFL, ZFR, ZRL, and ZRR, and identifies the displacement sensor 11 that outputs the sensor signal Z containing an error component e equal to or greater than a threshold value. Then, it is determined that the faulty part is either the attachment part to which the identified displacement sensor 11 is attached, the component part to which the identified displacement sensor 11 is attached, or the identified displacement sensor 11 itself.

[0029] This makes it possible to identify the location of the displacement sensor 11 among the displacement sensors 11FL, 11FR, 11RL, and 11RR in which the displacement sensor 11 itself, the attached parts, or the components are faulty, even if the value of the sensor signal Z is within the normal range Rn despite the fact that the displacement sensor 11 itself, the attached parts, or the components are faulty.

[0030] 4 is a block diagram showing an example of the functional configuration of the suspension controller 12 according to the first embodiment. The suspension controller 12 includes a stroke calculation unit 50, a mode component calculation unit 51, a fault location determination unit 56, and a recombination unit 57. The stroke calculation unit 50 calculates the wheel strokes of the left front wheel 2FL, the right front wheel 2FR, the left rear wheel 2RL, and the right rear wheel 2RR based on the sensor signals ZFL, ZFR, ZRL, and ZRR. For example, the stroke calculation unit 50 may calculate the wheel strokes using the characteristic map shown in FIG. 3(b). The stroke calculation unit 50 outputs the calculated wheel strokes to the automatic braking controller 23 of the automatic braking device 20.

[0031] The mode component calculation unit 51 calculates the mode components of the behavior of the mounting plane (i.e., the mode components of the vehicle body behavior of the vehicle body 6) based on the sensor signals ZFL, ZFR, ZRL, and ZRR. For example, the mode component calculation unit 51 calculates the bounce component Z as the mode component of the behavior of the mounting plane based on the following equation (2) using a transformation matrix A defined by the following equation (1). B , roll component Z R , pitch component ZP and the warp component Z W may be calculated.

[0032]

number

[0033] In the above equation (1), the constants tdf, tdr, and WB are the front tread, rear tread, and wheelbase, respectively. As can be seen from the definition of the following equation (1), the warp component Z W is the difference between the sum of the wheel strokes of the wheels on one diagonal and the sum of the wheel strokes of the wheels on the other diagonal. In other words, the warp component Z W is the difference between the sum of displacements at one diagonal position and the sum of displacements at the other diagonal position among the four positions detected by the displacement sensors 11FL, 11FR, 11RL, and 11RR. The modal component calculation unit 51 calculates the warp component Z W is calculated as the amount of distortion of the mounting plane. The amount of distortion of the mounting plane is an example of the "amount of distortion of the same plane" in the claims. The amount of distortion of the mounting plane may be, for example, an error in the actual mounting position of the displacement sensor 11 relative to a virtual plane on which it is assumed that the displacement sensor 11 is mounted on the vehicle 1. The amount of distortion of the mounting plane may be, for example, the warp component ZW as described above, or may be defined by the distance from an approximate plane (least-squares plane) obtained by the least-squares method from the mounting positions of the multiple displacement sensors 11 to the mounting positions of each displacement sensor 11, or may be defined by the angle between a line connecting the mounting positions of each displacement sensor 11 and the least-squares plane.

[0034] The recombination unit 57 converts the modal components calculated by the modal component calculation unit 51 into the inverse matrix A of the transformation matrix A in the above equation (1). -1By multiplying by , the modal components are resynthesized (inversely converted) into signals in the form of sensor signals ZFL, ZFR, ZRL, and ZRR. In the following description, the signal in the form of a sensor signal resynthesized by resynthesizer 57 will be referred to as a "resynthesized value," and the resynthesized values ​​corresponding to sensor signals ZFL, ZFR, ZRL, and ZRR will be referred to as "ZtgtFL," "ZtgtFR," "ZtgtRL," and "ZtgtRR," respectively. The resynthesized values ​​ZtgtFL, ZtgtFR, ZtgtRL, and ZtgtRR may be collectively referred to as the "resynthesized value Ztgt."

[0035] At this time, the recombination unit 57 calculates the displacement that each of the displacement sensors 11 should output based on the output results of the displacement sensors 11, assuming that the amount of distortion of the same plane is 0. Specifically, the warp component Z W By substituting "0" for and calculating the resynthesized value Ztgt, the resynthesized value Ztgt is estimated as the true value of the sensor signal Z. In this way, the resynthesized unit 57 calculates the resynthesized value Ztgt as an estimate of the true value of the sensor signal Z that is estimated to have been output from the displacement sensor 11 if there were no failure in the displacement sensor 11 itself, the mounting parts of this displacement sensor 11, or the component parts to which this displacement sensor 11 is mounted. Specifically, as shown in the following equation (3), the bounce component Z B , roll component Z R , pitch component Z P and the warp component Z W column vector (Z B ,Z R ,Z P ,Z W ) T Warp component Z of W Substitute "0" into the inverse matrix A -1 By multiplying these, the recombined values ​​ZtgtFL, ZtgtFR, ZtgtRL and ZtgtRR are calculated.

[0036]

number

[0037] The faulty part determination unit 56 calculates the difference e=|Z−Ztgt| between the sensor signal Z and the resynthesized value Ztgt for each of the displacement sensors 11FL, 11FR, 11RL, and 11RR as the error component e. The faulty part determination unit 56 identifies the displacement sensor 11 that outputs the sensor signal Z including the error component e equal to or greater than the determination threshold Eth among the displacement sensors 11FL, 11FR, 11RL, and 11RR. For example, the determination threshold Eth may be set according to the value of the error component that adversely affects the vehicle control of the vehicle 1 (e.g., vehicle control by the automatic braking device 20). For example, the determination threshold Eth may be set according to the value of the error component e that causes the automatic braking device 20 to malfunction.

[0038] When the difference between the output result of any one of the plurality of displacement sensors 11 and the calculated displacement is equal to or greater than a threshold value, the faulty part determination unit 56 determines that one of the plurality of displacement sensors 11, an attachment part that attaches any one of the displacement sensors 11 to the vehicle, or a component of the vehicle to which any one of the displacement sensors 11 is attached by an attachment part, is faulty. Specifically, the faulty part determination unit 56 determines that the identified displacement sensor 11 is the attachment part, the component to which the identified displacement sensor 11 is attached, or the identified displacement sensor 11 itself is the faulty part. Furthermore, when the sensor signal Z including the error component e equal to or greater than the determination threshold value Eth is detected, the automatic braking controller 23 is notified of the occurrence of a fault. The faulty part determination unit 56 may detect a fault in the displacement sensor 11 itself, an attached part, or a component part when the state in which the error component e is equal to or greater than the determination threshold value Eth continues for a predetermined time Tth2 or more. For example, the predetermined time Tth2 may be set according to the time required from the time the displacement sensor 11 detects the wheel stroke to the time the automatic braking device 20 drives the brake actuator 24 to activate the braking device.

[0039] (operation) FIG. 5 is a flowchart of an example of the failure determination method according to the first embodiment. In step S1, the displacement sensor 11 detects displacements at a plurality of positions on the vehicle body 6 located within the mounting plane. In step S2, the mode component calculation unit 51 calculates the mode component of the behavior of the mounting plane (bounce component Z) from the output result of the displacement sensor 11 (sensor signal Z). B , roll component Z R , pitch component Z P and the warp component Z W ) is calculated. In step S13, the recombination unit 57 converts the column vector (Z B ,Z R ,Z P ,Z W ) T Warp component Z of W Substitute "0" into the inverse matrix A -1 The recombined value Ztgt is calculated by multiplying the above values ​​by .

[0040] In step S14, the faulty part determination unit 56 calculates the difference e=|Z−Ztgt| between the sensor signal Z and the resynthesized value Ztgt as the error component e. In step S15, the faulty part determination unit 56 identifies the displacement sensor 11 that outputs the sensor signal Z containing the error component e equal to or greater than the determination threshold Eth, and determines that the faulty part is either the attachment part of the identified displacement sensor 11, the component part to which the identified displacement sensor 11 is attached, or the identified displacement sensor 11 itself. Then, the processing ends.

[0041] (Second embodiment) The suspension controller 12 of the second embodiment determines whether a failure has occurred in the displacement sensor 11 itself or in an attached part or component. For this reason, the suspension controller 12 of the second embodiment calculates the amount of distortion of the mounting plane based on the sensor signal Z. It also determines whether each sensor signal Z is within a predetermined range. If each sensor signal Z is within the predetermined range (i.e., it is considered that there is no malfunction in the displacement sensor 11 itself) and if there is no malfunction in the mounting parts and components, it is considered that no distortion will occur in the mounting plane.

[0042] Therefore, if each sensor signal Z is within a predetermined range and the amount of distortion of the mounting plane is equal to or greater than a threshold value, the suspension controller 12 determines that a failure has occurred in at least one of the mounting part and the component part. This makes it possible to detect a failure in a mounting part or component even if the value of the sensor signal Z is within the normal range Rn despite the failure occurring in the mounting part or component. It is also possible to determine whether the failure is occurring in the displacement sensor 11 itself or in the mounting part or component.

[0043] 6 is a block diagram showing an example of the functional configuration of the suspension controller 12 of the second embodiment. In addition to the stroke calculation unit 50, mode component calculation unit 51, and fault location determination unit 56 described above, the suspension controller 12 of the second embodiment also includes a power supply failure detection unit 52, a sensor failure detection unit 53, a stroke abnormality detection unit 54, and a characteristic abnormality detection unit 55. Note that the functions of the suspension controller 12 of the first embodiment and the functions of the suspension controller 12 of the second embodiment may be combined.

[0044] The power supply failure detection unit 52 detects a power supply failure and a harness failure. For example, the power supply failure detection unit 52 may detect a power supply failure and a harness failure based on the sensor failure signal Sf output by the displacement sensor 11. Alternatively, for example, the power supply failure detection unit 52 may detect a power supply failure and a harness failure when the power supply voltage supplied to the suspension controller 12 falls outside a predetermined allowable range.

[0045] The sensor failure detection unit 53 detects a failure that has occurred in the displacement sensor 11 itself for each of the displacement sensors 11FL, 11FR, 11RL, and 11RR. In the following description, a failure in the displacement sensor 11 itself may be referred to as a "sensor failure." For example, when the sensor signal Z of a certain displacement sensor 11 is not within the normal range Rn, the sensor failure detection unit 53 may determine that a sensor failure has occurred in that displacement sensor 11. Furthermore, for example, the sensor failure detection unit 53 may detect an offset failure (i.e., the offset of the sensor signal Z with respect to the actual arm angle θ is equal to or greater than a tolerance threshold) as a sensor failure. For example, the sensor failure detection unit 53 may detect an offset failure based on the sensor failure signal Sf.

[0046] The stroke abnormality detection unit 54 determines a failure in which the wheel stroke exceeds the design range as a range-out failure. For example, a range-out failure occurs due to deformation of the body frame or a failure of the damper 7. For example, the stroke abnormality detection unit 54 determines the bounce component Z calculated by the mode component calculation unit 51 as a range-out failure. B , roll component Z R , or pitch component Z P If any of the above exceeds a determination threshold, a range-out fault is detected.

[0047] The characteristic abnormality detection unit 55 detects an abnormality in the output characteristic of the sensor signal Z relative to the wheel stroke. In the following description, an abnormality in the output characteristic of the sensor signal Z relative to the wheel stroke may be referred to as a "characteristic abnormality." For example, the characteristic abnormality detection unit 55 detects the warp component Z calculated by the mode component calculation unit 51. W The occurrence of a characteristic abnormality may be detected when the threshold value Wth is equal to or greater than the threshold value Wth. For example, the threshold value Wth is the value of the warp component Z when an error in the sensor signal Z due to a failure of an attachment or component becomes large enough to adversely affect vehicle control of the vehicle 1 (for example, vehicle control by the automatic braking device 20). W For example, the determination threshold Wth may be set according to the value of the warp component Z when an error in the sensor signal Z due to a failure of an attachment or component becomes large enough to cause a malfunction of the automatic braking device 20. Wmay be set according to the value of

[0048] Furthermore, for example, the characteristic abnormality detection unit 55 detects the warp component Z W The occurrence of a characteristic abnormality may be detected when the state where the wheel stroke is equal to or greater than the determination threshold Wth continues for a predetermined time Tth1 or more. For example, the predetermined time Tth1 may be set according to the time required from when the displacement sensor 11 detects the wheel stroke to when the automatic braking device 20 drives the brake actuator 24 to operate the brake device.

[0049] The faulty part determination unit 56 determines the faulty part based on the detection results of the power supply fault detection unit 52, the sensor fault detection unit 53, the stroke abnormality detection unit 54, and the characteristic abnormality detection unit 55. The faulty part determination unit 56 also notifies the automatic braking controller 23 of the occurrence of a fault. For example, when a power supply failure or harness failure is detected, the failure part determination unit 56 may determine that the failure part is the power supply (battery) or the harness.

[0050] Furthermore, for example, when a range-out failure is detected, the failure part determination unit 56 may determine that the failure part is the vehicle body frame or the damper 7. Furthermore, for example, if a failure in the sensor itself is detected, the faulty part determination unit 56 may determine that any one of the displacement sensors 11FL, 11FR, 11RL, and 11RR in which the failure in the sensor itself is detected is the faulty part.

[0051] Also, for example, if the occurrence of a characteristic anomaly is detected (i.e., the warp component Z W is equal to or greater than the determination threshold Wth) and no failure is detected in the sensor itself, the faulty part determination unit 56 may determine that an attached part or a component part is the faulty part. If both the occurrence of a characteristic abnormality and a failure of the sensor itself are detected, the failure part determination unit 56 may determine that the failure parts are both the attached part or component and the displacement sensor 11. Alternatively, it may determine that the failure part is the displacement sensor 11 and that the attached part or component is not the failure part.

[0052] 7 is a flowchart of an example of a failure determination method according to the second embodiment. The processes in steps S11 and S12 are the same as those in steps S1 and S2 in FIG. In step S13, the sensor failure detection unit 53 determines whether the output of the displacement sensor 11 is outside a predetermined range. For example, the sensor failure detection unit 53 may determine whether the sensor signal Z is outside the normal range Rn. Alternatively, for example, the sensor failure detection unit 53 may determine whether the offset of the sensor signal Z with respect to the actual arm angle θ is equal to or greater than an allowable threshold.

[0053] If the output of the displacement sensor 11 is not outside the predetermined range (step S13: N), the process proceeds to step S15. If the output of the displacement sensor 11 is outside the predetermined range (step S13: Y), the process proceeds to step S14. In step S14, the faulty part determination unit 56 determines that the displacement sensor 11 itself, which has output the sensor signal Z outside the predetermined range, is the faulty part, and then the process ends.

[0054] In step S15, the characteristic abnormality detection unit 55 calculates the warp component Z W It is determined whether the warp component Z is equal to or greater than the threshold value Wth. W If the warp component Z is not equal to or greater than the threshold value Wth (step S15: N), the process proceeds to step S17. W If is equal to or greater than the determination threshold Wth (step S15: Y), the process proceeds to step S16. In step S16, the faulty part determination unit 56 determines that the attached part or component part is the faulty part, and then the process ends.

[0055] In step S17, the faulty part determination unit 56 determines that there is no faulty part. If a power supply failure or harness failure is detected, the faulty part determination unit 56 may determine that the power supply or harness is the faulty part. Also, if a range-out failure is detected, for example, the faulty part determination unit 56 may determine that the body frame or the damper 7 is the faulty part. Then, the processing ends.

[0056] (Effects of the embodiment) (1) At least four of the plurality of displacement sensors 11 respectively detect displacements at a plurality of positions on approximately the same plane on the vehicle body 6. Based on the output results of the plurality of displacement sensors 11, the suspension controller 12 calculates the displacement that each of the plurality of displacement sensors 11 should output if it is assumed that the amount of distortion of the same plane is zero, and if the difference between the output result of any of the plurality of displacement sensors 11 and the calculated displacement is equal to or greater than a threshold value, it determines that any of the plurality of displacement sensors 11, an attachment part that attaches any of the displacement sensors to the vehicle 1, or a component of the vehicle 1 to which any of the displacement sensors is attached by an attachment part has failed.

[0057] This allows the location of the fault to be determined when multiple displacement sensors are used to detect the displacements at multiple locations on the vehicle body. Furthermore, by identifying the location of the fault, it is possible to narrow down the locations that need to be replaced or repaired. Furthermore, the threshold value used to determine whether or not a failure has occurred can be directly set based on the allowable error range for the sensor signal Z of the displacement sensor 11.

[0058] Furthermore, the abnormality determination device of Patent Document 1 cannot determine a malfunction until a certain period of time has passed during which the integrated value is accumulated, whereas the present embodiment requires less time for determination compared to the abnormality determination device of Patent Document 1. Furthermore, the abnormality determination device of Patent Document 1 cannot determine a malfunction while the vehicle 1 is stopped and can only determine a malfunction while the vehicle is traveling straight, whereas the present embodiment can determine a malfunction even in these situations. Furthermore, the abnormality determination device of Patent Document 1 can easily detect a fault that changes instantaneously, but has difficulty detecting a fault that causes a constant offset to continue. This embodiment can detect a fault that causes a constant offset to continue in the same way as a fault that changes instantaneously.

[0059] (2) If the difference remains equal to or greater than the threshold for a predetermined period of time or longer, the suspension controller 12 may determine that at least one of the displacement sensors, the mounting part to which the displacement sensor is attached, or the component to which the displacement sensor is attached has failed. This can reduce erroneous determinations due to temporary noise in the output of the displacement sensor.

[0060] (3) The threshold value may be set according to the magnitude of the distortion of the same plane that adversely affects vehicle control based on the output result of the displacement sensor. For example, the magnitude of the distortion that adversely affects vehicle control may be a magnitude that causes a malfunction of an automatic braking device that brakes the vehicle. Furthermore, the predetermined time may be set according to the time required from the time the displacement sensor detects a displacement of a position on the vehicle body to the time the automatic braking device that brakes the vehicle activates the brakes based on the output result of the displacement sensor. This allows the determination threshold value and determination time for detecting a failure of the displacement sensor, attached parts, or components to be appropriately set. [Explanation of symbols]

[0061] 1...vehicle, 2...wheel, 2FL...left front wheel, 2FR...right front wheel, 2RL...left rear wheel, 2RR...right rear wheel, 3...knuckle, 4...upper arm, 5...lower arm, 6...vehicle body, 7...damper, 8...spring, 10...displacement detection device, 11...displacement sensor, 11FL, 11FR, 11RL, 11RR...displacement sensor, 11a...arm, 11b...sensor body, 12...suspension controller, 13, 25...processor, 14, 26...storage device, 20...automatic braking device, 21...camera, 22...distance measuring device, 23...automatic braking controller, 24...brake actuator, 30, 32...bracket, 31...shaft, 50...stroke calculation unit, 51...mode component calculation unit, 52...power supply failure detection unit, 53...sensor failure detection unit, 54...stroke abnormality detection unit, 55...characteristic abnormality detection unit, 56...failure location determination unit, 57...recombination unit

Claims

1. Detecting displacements at at least four positions on a vehicle body that are substantially in the same plane using a plurality of displacement sensors, respectively; calculating, based on the output results of the plurality of displacement sensors, displacements that should be output by the plurality of displacement sensors when it is assumed that the distortion amount of the same plane is 0; When a difference between an output result of any one of the plurality of displacement sensors and the calculated displacement is equal to or greater than a threshold value, it is determined that any one of the plurality of displacement sensors, an attachment part that attaches any one of the displacement sensors to the vehicle, or a component of the vehicle to which any one of the displacement sensors is attached via the attachment part has failed. A failure determination method characterized by:

2. 2. The failure determination method according to claim 1, wherein, when the difference remains equal to or greater than the threshold value for a predetermined period of time or longer, it is determined that at least one of the displacement sensors, the attachment part to which the displacement sensor is attached, or the component part to which the displacement sensor is attached has failed.

3. 3. The fault determination method according to claim 2, wherein the threshold value is set in accordance with the magnitude of the distortion of the same plane that adversely affects vehicle control based on the output result of the displacement sensor.

4. 4. The failure determination method according to claim 3, wherein the magnitude of the distortion that adversely affects vehicle control is a magnitude that causes a malfunction of an automatic braking device that brakes the vehicle.

5. 3. The failure determination method according to claim 2, wherein the predetermined time is set according to the time required from the time when the displacement sensor detects a displacement of the position on the vehicle body to the time when an automatic braking device that brakes the vehicle operates the brakes based on the output result of the displacement sensor.

6. a plurality of displacement sensors that detect displacements at at least four positions on a vehicle body that are substantially in the same plane; a controller that calculates, based on output results of the plurality of displacement sensors, a displacement that should be output by each of the plurality of displacement sensors when it is assumed that the distortion amount of the same plane is zero, and determines, when a difference between the output result of any of the plurality of displacement sensors and the calculated displacement is equal to or greater than a threshold, that any of the plurality of displacement sensors, an attachment part that attaches any of the displacement sensors to the vehicle, or a component of the vehicle to which any of the displacement sensors is attached via the attachment part, has failed; A failure determination device comprising:

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