Failure determination method and failure determination device

Abstract

This failure determination method comprises: detecting, with each of a plurality of displacement sensors, displacement of at least four of a plurality of locations forming substantially the same plane on a vehicle body (S1); computing an amount of deformation of the same plane on the basis of output results of the plurality of displacement sensors (S2); and on the basis of whether the amount of deformation of the same plane is at or above a threshold value, and whether the output results of the displacement sensors are outside a predetermined range, determining whether the failure is in an attachment component attaching a displacement sensor to a vehicle and / or a constituent component of the vehicle to which the displacement sensor is attached by the attachment component, or in the displacement sensor (S3 to S6).

Description

Fault determination method and fault determination device

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

[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 period of time, and determines an abnormality when the deviation between the calculated front and rear integrated values ​​is equal to or greater than a threshold value.

[0003] Japanese Patent Application Laid-Open No. 2007-015633

[0004] The abnormality determination device of Patent Document 1 cannot identify the failure mode (i.e., the type of failure) when it determines an abnormality in the output of the stroke sensor. For example, it cannot determine whether the failure is in the stroke sensor itself, the attachment that attaches the stroke sensor to the vehicle, or a component of the vehicle to which the stroke sensor is attached. The present invention aims to determine whether, when detecting a displacement on a vehicle body using a displacement sensor, at least one of the attachment that attaches the displacement sensor to the vehicle and the component of the vehicle to which the displacement sensor is attached is faulty, or whether the displacement sensor itself is faulty.

[0005] In one aspect of the failure determination method of the present invention, displacements of at least four positions on a vehicle body that form approximately the same plane are detected by each of a plurality of displacement sensors, the amount of distortion of the same plane is calculated based on the output results of the plurality of displacement sensors, and based on whether the amount of distortion of the same plane is equal to or greater than a threshold value and whether the output result of the displacement sensor is outside a predetermined range, it is determined whether at least one of the attachment part that attaches the displacement sensor to the vehicle or the component of the vehicle to which the displacement sensor is attached by the attachment part is faulty, or whether the displacement sensor itself is faulty.

[0006] According to the present invention, when a displacement of a position on a vehicle body is detected by a displacement sensor, it is possible to determine whether at least one of a mounting part for mounting the displacement sensor on the vehicle and a component of the vehicle to which the displacement sensor is attached is faulty, or whether the displacement sensor itself is faulty. The objects and advantages of the present invention are realized and attained by using the elements and combinations thereof set forth in the appended claims. It should be understood that both the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the invention as defined by the claims.

[0007] FIG. 1 is a schematic configuration diagram of an example of a vehicle equipped with a displacement detection device as an embodiment of a failure determination device. FIG. 2 is a diagram showing an example of the configuration of a suspension device. (a) and (b) are explanatory diagrams of a displacement sensor. FIG. 3 is a block diagram of an example of the functional configuration of a suspension controller of a first embodiment. FIG. 4 is a flowchart of an example of a failure determination method of the first embodiment. FIG. 5 is a block diagram of an example of the functional configuration of a suspension controller of a second embodiment. FIG. 6 is a flowchart of an example of a failure determination method of the second embodiment.

[0008] (First embodiment) (Configuration) Fig. 1 is a schematic configuration 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 vehicle body. The displacement detection device 10 is equipped with displacement sensors 11FR, 11RL, 11RR, and 11RL, and a suspension controller 12.

[0009] 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 front left wheel 2FL, front right wheel 2FR, rear left wheel 2RL, and rear right 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.

[0010] In the following description, the front left wheel 2FL, front right wheel 2FR, rear left wheel 2RL, and rear right 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 sensors 11," and the sensor signals ZFL, ZFR, ZRL, and ZRR may be collectively referred to as "sensor signal Z."

[0011] An example of the 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 unit Sus that suspends a wheel 2 of a vehicle 1. The suspension unit 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. A 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 ​​fixed to the upper arm 4.

[0012] Therefore, when the wheel center of the wheel 2 is displaced 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 axis that attaches the arm 11a to the sensor main body 11b as the axis of rotation. The displacement sensor 11 detects an 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.

[0013] 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.

[0014] The mounting positions of the sensor bodies 11b of the displacement sensors 11FL, 11FR, 11RL, and 11RR are determined to be substantially coplanar (located within substantially the same plane). That is, the displacement sensors 11FL, 11FR, 11RL, and 11RR detect vertical displacements at the four positions on the substantially coplanar surface where the displacement sensors 11 are mounted. Note that "substantially the same plane" does not mean that the mounting positions of the displacement sensors 11 are located strictly within the same plane, but rather is intended to allow for errors due to variations in the vehicle 1 and mounting. For example, "substantially the same plane" may have an error of approximately 1 cm in the vertical direction relative to the exact plane. In the following description, the substantially coplanar surface where the sensor bodies 11b of the displacement sensors 11FL, 11FR, 11RL, and 11RR are mounted 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 may detect vertical displacement at five positions within the mounting plane.

[0015] 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 a power supply voltage that falls outside a predetermined tolerance 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, which indicates the result of detection of a power supply failure, harness failure, or offset failure by the displacement sensor 11, to the suspension controller 12.

[0016] Referring to 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 a 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 (e.g., a PLD such as an FPGA) configured in a general-purpose semiconductor integrated circuit.

[0017] 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 these failure determinations to the automatic braking controller 23.

[0018] The automatic braking device 20 measures the distance between the vehicle 1 and an obstacle ahead of the vehicle 1 (e.g., 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.

[0019] 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 (e.g., a PLD such as an FPGA) configured in a general-purpose semiconductor integrated circuit.

[0020] 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.

[0021] 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, 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.

[0022] Next, the process of determining whether or not the displacement sensor 11, attached parts, or components has failed in the suspension controller 12 will be described. 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 portion 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 the displacement sensor 11 can output 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."

[0023] The upper limit of the possible wheel stroke (range of motion Rss) determined by the mechanical constraints of the suspension unit 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) and outputs a sensor signal Za, and when the actual wheel stroke is at the lower limit Stb, the arm angle θ becomes angle θb (>θ2) and outputs a sensor signal Zb. Therefore, the normal output range Rn of the sensor signal Z is from Za to Zb, as shown by the dashed line in Figure 3(a).

[0024] Therefore, if the value of the sensor signal Z is within the abnormal ranges R1 and R2 outside the normal range Rn, a fault in the displacement sensor 11 itself can be detected from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, and ZRR. However, even if a 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 a fault occurs in the output characteristics of the sensor signal Z relative to the actual wheel stroke ( FIG. 3( b) ), the fault may not be detected from the individual values ​​of the sensor signals ZFL, ZFR, ZRL, and ZRR. For example, if a mounting part that attaches the displacement sensor 11 to the vehicle 1 or a component of the vehicle 1 to which the displacement sensor 11 is attached by the mounting part fails (e.g., breaks or deforms), an abnormality may occur in the output characteristics of the sensor signal Z relative to the actual wheel stroke.

[0025] The solid line Cn represents the characteristic line when the output characteristics of the sensor signal Z relative to the actual wheel stroke are normal, while the two-dot chain line Ca represents 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.

[0026] Therefore, the suspension controller 12 calculates the amount of distortion of the mounting plane based on the sensor signal Z. It also determines whether or not 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 there is no malfunction in the mounting parts and components, it is considered that no distortion occurs in 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 relative to a virtual plane on which the displacement sensor 11 is assumed to be mounted on the vehicle 1. For example, the amount of distortion of the mounting plane can be calculated by using the warp component Z described below. Ｗ Alternatively, the distance Z may be defined by the distance from an approximate plane (least-squares plane) calculated from the mounting positions of the multiple displacement sensors 11 using the least-squares method to the mounting positions of each displacement sensor 11, or by the angle between the least-squares plane and a line connecting the mounting positions of each displacement sensor 11. Therefore, if each sensor signal Z is within a predetermined range and the distortion of the mounting plane is equal to or greater than a threshold, the suspension controller 12 determines that a fault has occurred in at least one of the mounting parts or components. This allows the suspension controller 12 to detect a fault in a mounting part or component even if the value of the sensor signal Z is within the normal range Rn despite the fault occurring in the mounting part or component. Furthermore, it is possible to determine whether the fault is occurring in the displacement sensor 11 itself or in the mounting part or component.

[0027] FIG. 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 power supply failure detection unit 52, a sensor failure detection unit 53, a stroke abnormality detection unit 54, a characteristic abnormality detection unit 55, and a failure location determination unit 56. 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. 3B. The stroke calculation unit 50 outputs the calculated wheel strokes to the automatic braking controller 23 of the automatic braking device 20.

[0028] 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 Z Ｐ and the warp component Z Ｗ may be calculated.

[0029]

[0030] In the above formula (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 formula (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. Ｗ is the difference between the sum of the displacements at one diagonal position and the sum of the displacements at the other diagonal position among the four positions detected by the displacement sensors 11FL, 11FR, 11RL, and 11RR. Ｗ is calculated as the amount of distortion of the mounting plane.

[0031] 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.

[0032] The sensor failure detection unit 53 detects a failure occurring 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, the sensor failure detection unit 53 may determine that a sensor failure has occurred in a displacement sensor 11 when the sensor signal Z of that displacement sensor 11 is not within the normal range Rn. 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 tolerable 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.

[0033] The stroke abnormality detection unit 54 determines a fault in which the wheel stroke exceeds the design range as a range-out fault. For example, a range-out fault occurs due to deformation of the body frame or a fault in the damper 7. For example, the stroke abnormality detection unit 54 determines a range-out fault by detecting the bounce component Z calculated by the mode component calculation unit 51. 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.

[0034] 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 an abnormality in the output characteristic of the sensor signal Z relative to the wheel stroke. ＷThe occurrence of a characteristic abnormality may be detected when the error of the sensor signal Z due to a failure of an attachment part or a component is large enough to adversely affect the vehicle control of the vehicle 1 (for example, the vehicle control by the automatic braking device 20). Ｗ For example, the determination threshold value 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 part or component becomes large enough to cause a malfunction of the automatic braking device 20. Ｗ may be set according to the value of

[0035] 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 value Wth continues for a predetermined time Tth1 or more. For example, the predetermined time Tth1 may be set according to the time required from the time when the displacement sensor 11 detects the wheel stroke to the time when the automatic braking device 20 drives the brake actuator 24 to operate the brake device.

[0036] 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.

[0037] For example, if a power supply failure or harness failure is detected, the faulty part determination unit 56 may determine that the faulty part is the power supply (battery) or the harness. Alternatively, if a range-out failure is detected, the faulty part determination unit 56 may determine that the faulty part is the vehicle body frame or the damper 7. Alternatively, if a sensor failure is detected, the faulty part determination unit 56 may determine that any one of the displacement sensors 11FL, 11FR, 11RL, and 11RR in which a sensor failure has been detected is the faulty part.

[0038] Furthermore, for example, when the occurrence of a characteristic abnormality is detected (i.e., when the warp component Z Ｗis equal to or greater than the determination threshold Wth) and no failure of the sensor itself is detected, the failure part determination unit 56 may determine that an attached part or a component part is the failed part. Note that, when 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 both the attached part or component part and the displacement sensor 11 are the failed parts. Alternatively, it may determine that the displacement sensor 11 is the failed part and that the attached part or component part is not the failed part.

[0039] (Operation) Fig. 5 is a flowchart of an example of a 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 mode components (bounce components Z) of the behavior of the mounting plane from the output result (sensor signal Z) of the displacement sensor 11. Ｂ , roll component Z Ｒ , pitch component Z Ｐ and the warp component Z Ｗ ) is calculated.

[0040] In step S3, 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. If the output of the displacement sensor 11 is not outside the predetermined range (step S3: N), the process proceeds to step S5. If the output of the displacement sensor 11 is outside the predetermined range (step S3: Y), the process proceeds to step S4.

[0041] In step S4, 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. Then, the process ends. In step S5, the characteristic abnormality detection unit 55 determines that the warp component Z Ｗ It is determined whether the warp component Z is equal to or greater than the determination threshold Wth. Ｗ If the warp component Z is not equal to or greater than the determination threshold Wth (step S5: N), the process proceeds to step S7. ＷIf is equal to or greater than the determination threshold Wth (step S5: Y), the process proceeds to step S6.

[0042] In step S6, the faulty part determination unit 56 determines that an attached part or a component part is the faulty part. Then, the processing ends. In step S7, 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, for example, if a range-out failure is detected, the faulty part determination unit 56 may determine that the vehicle body frame or the damper 7 is the faulty part. Then, the processing ends.

[0043] Second Embodiment A suspension controller 12 of a second embodiment determines the location of a displacement sensor 11 among displacement sensors 11FL, 11FR, 11RL, and 11RR at which a failure has occurred in the displacement sensor 11 itself or in an attached part or component. To this end, the suspension controller 12 of the second embodiment 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 a sensor signal Z containing an error component e equal to or greater than a threshold value.

[0044] The system then determines that the faulty part is either the mounting 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. Figure 6 is a block diagram of an example of the functional configuration of the suspension controller 12 of the second embodiment. The suspension controller 12 of the second embodiment includes a re-synthesis unit 57 in addition to the stroke calculation unit 50, mode component calculation unit 51, and faulty part determination unit 56 described above. 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.

[0045] 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 recombined (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 recombined by the recombiner 57 will be referred to as a "recombined value," and the recombined values ​​corresponding to the sensor signals ZFL, ZFR, ZRL, and ZRR will be referred to as "ZtgtFL," "ZtgtFR," "ZtgtRL," and "ZtgtRR," respectively. The recombined values ​​ZtgtFL, ZtgtFR, ZtgtRL, and ZtgtRR may be collectively referred to as the "recombined value Ztgt."

[0046] At this time, the recombination unit 57 calculates the displacements that should be output from the plurality of displacement sensors 11 based on the output results of the plurality of displacement sensors 11, assuming that the amount of distortion on the same plane is 0. Specifically, the warp component Z Ｗ By substituting "0" for and calculating the resynthesis value Ztgt, the resynthesis value Ztgt is estimated as the true value of the sensor signal Z. In this way, the resynthesis unit 57 calculates the resynthesis 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 components 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 Ｗ Substitute "0" into the inverse matrix A －１ By multiplying these, the recombined values ​​ZtgtFL, ZtgtFR, ZtgtRL and ZtgtRR are calculated.

[0047]

[0048] 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 among the displacement sensors 11FL, 11FR, 11RL, and 11RR that outputs a sensor signal Z containing an error component e equal to or greater than the determination threshold Eth. For example, the determination threshold Eth may be set according to the value of an error component that adversely affects 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 is large enough to cause a malfunction of the automatic braking device 20.

[0049] When 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, the faulty part determination unit 56 determines that one of the plurality of displacement sensors 11, an attachment part that attaches any of the displacement sensors 11 to the vehicle 1, or a component of the vehicle to which any of the displacement sensors 11 is attached via 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 faulty. Furthermore, when the sensor signal Z including the error component e equal to or greater than the determination threshold Eth is detected, the faulty part determination unit 56 notifies the automatic braking controller 23 of the occurrence of a fault. The faulty part determination unit 56 may detect a fault in the displacement sensor 11 itself, the attachment part, or the component if the state in which the error component e is equal to or greater than the determination threshold Eth continues for a predetermined time Tth2 or longer. For example, the predetermined time Tth2 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 activate the braking device.

[0050] 7 is a flowchart of an example of a fault 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. 5. In step S13, the recombiner 57 converts the column vector (Z Ｂ , Z Ｒ , Z Ｐ , Z Ｗ )Ｔ Warp component Z Ｗ Substitute "0" into the inverse matrix A －１ The recombined value Ztgt is calculated by multiplying the above values ​​by the above formula.

[0051] 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 attached part of the identified displacement sensor 11, the component to which the identified displacement sensor 11 is attached, or the identified displacement sensor 11 itself. Then, the processing ends.

[0052] (Effects of the embodiment) (1) At least four of the plurality of displacement sensors 11 respectively detect displacements at a plurality of positions that form approximately the same plane on the vehicle body 6. The suspension controller 12 calculates the amount of distortion of the same plane based on the output results of the plurality of displacement sensors 11, and determines whether at least one of the attachment parts that attach the displacement sensors 11 to the vehicle 1 or the components of the vehicle 1 to which the displacement sensors 11 are attached by the attachment parts has failed, or whether the displacement sensors 11 themselves have failed, based on whether the amount of distortion of the same plane is equal to or greater than a threshold value and whether the output results of the displacement sensors 11 are outside a predetermined range.

[0053] This makes it possible to determine whether at least one of the attachment part that attaches the displacement sensor 11 to the vehicle 1 and the component of the vehicle 1 to which the displacement sensor 11 is attached is faulty, or whether the displacement sensor 11 itself is faulty. In other words, the failure mode can be identified. By identifying the failure mode, it is possible to narrow down the parts that need to be replaced or repaired. Furthermore, by being able to subdivide the failure mode, it becomes possible to subdivide the warranty analysis, thereby improving the efficiency of defect countermeasures.

[0054] Furthermore, the abnormality determination device of Patent Document 1 cannot determine a fault until a certain period of time has elapsed during which the integrated value is accumulated, whereas the present embodiment requires less time for determination than the abnormality determination device of Patent Document 1. Furthermore, the abnormality determination device of Patent Document 1 cannot determine a fault while the vehicle 1 is stopped and can only determine a fault while the vehicle 1 is traveling straight, whereas the present embodiment can determine a fault even in these situations. Furthermore, the abnormality determination device of Patent Document 1 can easily detect faults that change momentarily, but has difficulty detecting faults that cause a constant offset to continue. The present embodiment can detect faults that cause a constant offset to continue in the same way as faults that change momentarily.

[0055] (2) If the amount of distortion in the same plane 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 mounting part on which the displacement sensor 11 is mounted or the component to which the displacement sensor 11 is mounted is faulty. This can reduce erroneous determinations due to temporary noise in the output of the displacement sensor.

[0056] (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 an attached part or component to be appropriately set.

[0057] (4) At least four of the plurality of displacement sensors 11 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 on 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.

[0058] 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 the fault can be directly set based on the allowable error range for the sensor signal Z of the displacement sensor 11.

[0059] Furthermore, the abnormality determination device of Patent Document 1 cannot determine a fault until a certain period of time has elapsed during which the integrated value is accumulated, whereas the present embodiment requires less time for determination than the abnormality determination device of Patent Document 1. Furthermore, the abnormality determination device of Patent Document 1 cannot determine a fault while the vehicle 1 is stopped and can only determine a fault while the vehicle 1 is traveling straight, whereas the present embodiment can determine a fault even in these situations. Furthermore, the abnormality determination device of Patent Document 1 can easily detect faults that change momentarily, but has difficulty detecting faults that cause a constant offset to continue. The present embodiment can detect faults that cause a constant offset to continue in the same way as faults that change momentarily.

[0060] (5) 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 makes it possible to prevent erroneous determinations due to temporary noise in the output of the displacement sensor.

[0061] (6) The threshold value in (5) above 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 in (5) above may be set according to the time required from the time the displacement sensor detects a positional displacement 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 component parts to be appropriately set.

[0062] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention.

[0063] 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 portion, 11b...sensor main body, 12...suspension controller, 13, 25...processor , 14, 26...storage device, 20...automatic braking device, 21...camera, 22...range 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 portion determination unit, 57...recombination unit

Claims

1. A failure determination method comprising the steps of: detecting displacements of at least four positions on a vehicle body that form approximately the same plane using a plurality of displacement sensors; calculating the amount of distortion of the same plane based on the output results of the plurality of displacement sensors; and determining whether at least one of an attachment part that attaches the displacement sensor to the vehicle or a component of the vehicle to which the displacement sensor is attached by the attachment part is faulty, or whether the displacement sensor itself is faulty, based on whether the amount of distortion of the same plane is equal to or greater than a threshold value and whether the output result of the displacement sensor is outside a predetermined range.

2. The fault determination method according to claim 1, characterized in that if the amount of distortion of the same plane remains above a threshold for a predetermined period of time or longer, it is determined that at least one of the mounting part on which the displacement sensor is attached or the component part to which the displacement sensor is attached is faulty.

3. The fault detection method according to claim 2, characterized in that the threshold value is 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.

4. A fault detection method according to claim 3, characterized in that 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. A fault detection method as described in claim 2, characterized in that 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 based on the output result of the displacement sensor activates the brakes.

6. A failure determination device comprising: a plurality of displacement sensors that respectively detect displacements at at least four positions on a vehicle body that form approximately the same plane; and a controller that calculates the amount of distortion of the same plane based on the output results of the plurality of displacement sensors, and determines whether at least one of an attachment part that attaches the displacement sensor to the vehicle or a component of the vehicle to which the displacement sensor is attached by the attachment part is faulty, or whether the displacement sensor itself is faulty, based on whether the amount of distortion of the same plane is equal to or greater than a threshold value and whether the output results of the plurality of displacement sensors are outside a predetermined range.

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