Proximity sensor system, steering device, and method for diagnosing a fault in a proximity sensor

Abstract

To provide a proximity sensor system that enables a relatively simple configuration to diagnose presence or absence of a failure of a proximity sensor.SOLUTION: A proximity sensor system comprises: a plurality of proximity sensors 4 to 7 that detect proximity of a human body to a steering handle; and a failure diagnosis device 8 that diagnoses presence or absence of the failure of the proximity sensors 4 to 7. The proximity sensors 4 to 7 includes respectively electrode parts 40 to 70 provided in a different position of the steering handle; a power source circuit 45 applying a voltage of an oscillation frequency to the electrode part; and a measurement circuit 46 measuring an electric characteristic of the electrode part. The failure diagnosis device 8 is configured to set at least two of the plurality of proximity sensors 4 to 7 as an oscillation object and a diagnosis object; acquire a measurement result of the electric characteristic by the measurement circuit of the diagnosis object in a duration of generating an electromagnetic wave of the oscillation frequency by the power source of the oscillation object; and diagnose presence or absence of the failure of the diagnosis object on the basis of the measurement result.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a proximity sensor system, a steering device, and a method for diagnosing a fault in a proximity sensor, and more particularly to a proximity sensor system, a steering device, and a method for diagnosing a fault in a plurality of proximity sensors. [Background technology]

[0002] In recent years, efforts to provide access to sustainable transport systems that take into consideration vulnerable transport participants have been gaining momentum. To achieve this, we are focusing on research and development into driver assistance technologies that help drivers recognize their surroundings, thereby further improving road safety and convenience.

[0003] In the contact detection device shown in Patent Document 1, a capacitance sensor provided on the steering wheel is used to determine whether or not the driver is gripping the steering wheel. Patent Document 1 also describes a technique related to a fault diagnosis method for a contact detection device using a capacitance sensor. More specifically, in the fault diagnosis method described in Patent Document 1, an estimation means is used to estimate whether or not a human body is in contact with the steering wheel, and fault diagnosis related to the capacitance sensor is performed based on the detection result of the capacitance sensor when the estimation means estimates that there is contact and the detection result of the capacitance sensor when the estimation means estimates that there is no contact. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-129139 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the fault diagnosis method disclosed in Patent Document 1 requires estimation of whether or not a human body is in contact with the steering wheel using estimation means other than a contact detection device, which may result in high processing load and costs.

[0006] The present invention aims to provide a proximity sensor system, a steering device, and a fault diagnosis method that can diagnose whether or not a proximity sensor is faulty with a relatively simple configuration, and ultimately to contribute to the development of a sustainable transportation system. [Means for solving the problem]

[0007] (1) A proximity sensor system according to the present invention (e.g., proximity sensor system S described later) includes a plurality of proximity sensors (e.g., proximity sensors 4 to 7 described later) that detect the proximity of a target object (e.g., human body H described later) to a target structure (e.g., steering wheel 2 described later), and a fault diagnosis device (e.g., fault diagnosis device 8 described later) that diagnoses the presence or absence of a fault in the proximity sensors, each of the plurality of proximity sensors including an electrode portion (e.g., upper right electrode portion 40 described later) provided at a different position of the target structure, a power supply circuit (e.g., power supply circuit 45 described later) that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit (e.g., measurement circuit 46 described later) that measures an electrical characteristic of the electrode portion, and the fault diagnosis device sets at least two of the plurality of proximity sensors as an oscillation target and a diagnosis target, obtains a measurement result of the electrical characteristic by the measurement circuit of the diagnosis target while the power supply circuit of the oscillation target is generating an electromagnetic wave of the oscillation frequency, and diagnoses the presence or absence of a fault in the diagnosis target based on the measurement result.

[0008] (2) In this case, it is preferable that the fault diagnosis device disconnects the electrode portion of the diagnosis object from the power supply circuit and maintains the electrode portion connected to the measurement circuit while electromagnetic waves are being generated by the oscillation object.

[0009] (3) In this case, it is preferable that the fault diagnosis device determines the oscillation target from among the multiple proximity sensors in which the proximity of the target object is detected, and determines the diagnosis target from among those in which the proximity of the target object is not detected.

[0010] (4) In this case, it is preferable that the fault diagnosis device switches the settings of the oscillation target and the diagnosis target at a predetermined cycle.

[0011] (5) In this case, it is preferable that the measurement circuit measures the voltage of a capacitor (e.g., reference capacitor 461 described later) connected to the electrode portion via a switch (e.g., first switch 43 described later), and the fault diagnosis device diagnoses the presence or absence of a fault in the object to be diagnosed based on a comparison between the frequency of the voltage measured by the measurement circuit of the object to be diagnosed and the oscillation frequency of the power supply circuit of the object to be diagnosed.

[0012] (6) In this case, it is preferable that the fault diagnosis device diagnoses the presence or absence of a fault in the object to be diagnosed based on a comparison between a level of a voltage measured by the object to be diagnosed and a predetermined reference level.

[0013] (7) In this case, it is preferable that the fault diagnosis device diagnoses the presence or absence of a fault in the diagnosis object based on the number of occurrences of pulse-like fluctuations in voltage measured by the diagnosis object.

[0014] (8) In this case, it is preferable that the oscillation frequency differs for each proximity sensor.

[0015] (9) A steering device according to the present invention (e.g., steering device 1 described below) is characterized in that it comprises a steering handle (e.g., steering handle 2 described below) that accepts steering operations by a driver, a proximity sensor system described in any one of (1) to (4) (e.g., proximity sensor system S described below) provided on the steering handle as the target structure, and a grip determination device (e.g., grip determination device 9 described below) that determines whether or not the steering handle is being gripped based on the detection result of the proximity sensor.

[0016] (10) A fault diagnosis method according to the present invention is a method for diagnosing the presence or absence of a fault in a plurality of proximity sensors (e.g., proximity sensors 4 to 7 described below) that detect the proximity of a target object (e.g., a human body H described below) to a target structure (e.g., a steering wheel 2 described below), wherein each of the plurality of proximity sensors includes an electrode portion (e.g., an upper right electrode portion 40 described below) provided at a different position on the target structure, a power supply circuit (e.g., power supply circuit 45 described below) that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit (e.g., measurement circuit 46 described below) that measures the electrical characteristics of the electrode portion, and wherein at least one of the plurality of proximity sensors The method includes a first step (e.g., step ST2, step ST14, and step ST15 described below) of setting two as oscillation targets and diagnosis targets, a second step (e.g., step ST3, step ST4, step ST16, and step ST17 described below) of measuring electrical characteristics of the electrode portion using the measurement circuit of the diagnosis target while generating electromagnetic waves of the oscillation frequency using the power supply circuit of the oscillation target, and a third step (e.g., step ST6 and step ST19 described below) of diagnosing the presence or absence of a malfunction of the diagnosis target based on the measurement results in the second step. Effect of the Invention

[0017] (1) The proximity sensor system according to the present invention includes a plurality of proximity sensors that detect the proximity of a target object to a target structure, and a fault diagnosis device that diagnoses the presence or absence of a fault in these proximity sensors. Each of the proximity sensors includes an electrode portion provided at a different position on the target structure, a power supply circuit that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit that measures the electrical characteristics of the electrode portion. The fault diagnosis device sets at least two of the plurality of proximity sensors as an oscillation target and a diagnosis target. The fault diagnosis device also acquires a measurement result of the electrical characteristics of the diagnosis target by the measurement circuit while an electromagnetic wave of the oscillation frequency is generated from the electrode portion by the power supply circuit of the oscillation target, and diagnoses the presence or absence of a fault in the diagnosis target based on the measurement result. Here, when a voltage of the oscillation frequency is applied to the electrode portion by the power supply circuit of the oscillation target, an electromagnetic wave of the oscillation frequency is generated around the electrode portion. At this time, if there is no fault in the diagnosis target, the electrical characteristics of the electrode portion of the diagnosis target change due to the antenna induction effect between the oscillation target and the diagnosis target. Therefore, the presence or absence of a fault in the diagnosis target is correlated with the measurement result by the measurement circuit of the diagnosis target. Therefore, according to the present invention, the presence or absence of a fault can be diagnosed using at least two of a plurality of proximity sensors installed on the same target structure, thereby making it possible to diagnose the presence or absence of a fault in the proximity sensor with a relatively simple configuration, thereby contributing to the development of a sustainable transportation system.

[0018] (2) In the present invention, while the oscillation target is generating electromagnetic waves, the fault diagnosis device disconnects the electrode of the diagnosis target from the power supply circuit and maintains the electrode of the diagnosis target connected to the measurement circuit. Therefore, according to the present invention, it is possible to prevent the electrical characteristics of the electrode of the diagnosis target from fluctuating due to the influence of the voltage applied from the power supply circuit of the diagnosis target, and therefore it is possible to accurately diagnose whether the diagnosis target has a fault.

[0019] (3) In the above-mentioned proximity sensor, in order to detect whether a target object is close to a target structure, it is necessary to appropriately apply a voltage to the electrode portion by the power supply circuit. In contrast, in order to accurately diagnose the presence or absence of a fault as described above, it is preferable to maintain the connection between the electrode portion and the power supply circuit of the proximity sensor determined as the diagnosis target in a state in which it is disconnected. In other words, while the proximity sensor is determined as the diagnosis target, it cannot detect the presence or absence of the target object in proximity. Therefore, the fault diagnosis device according to the present invention determines an oscillation target from among a plurality of proximity sensors that detect the proximity of the target object, and determines a diagnosis target from among those that do not detect the proximity of the target object. In this way, the proximity sensor determined as the oscillation target can continue to detect the presence or absence of the target object in proximity, while simultaneously diagnosing the presence or absence of a fault in the proximity sensor determined as the diagnosis target.

[0020] (4) In the present invention, the fault diagnosis device switches the settings of the oscillation target and the diagnosis target at a predetermined cycle. As a result, even if a target structure is provided with many proximity sensors, the present invention can periodically diagnose whether or not all of these proximity sensors are faulty.

[0021] (5) As described above, when a voltage of an oscillation frequency is applied to the electrode part by the power supply circuit of the oscillation target, electromagnetic waves of the oscillation frequency are generated around the electrode part. At this time, if there is no fault in the diagnosis target, the voltage of the capacitor connected to the electrode part of the diagnosis target fluctuates at the same frequency as the oscillation frequency of the oscillation target due to the antenna induction effect between the oscillation target and the diagnosis target. Therefore, the fault diagnosis device diagnoses the presence or absence of a fault in the diagnosis target based on a comparison between the frequency of the capacitor voltage measured by the measurement circuit of the diagnosis target and the oscillation frequency of the power supply circuit of the oscillation target. This makes it possible to diagnose the presence or absence of a fault in the diagnosis target with high accuracy. Furthermore, according to the present invention, by comparing the frequencies, it may be possible to identify not only the presence or absence of a fault but also the type of the fault (e.g., an open fault).

[0022] (6) The voltage level of the capacitor connected to the electrode of the diagnosis object due to the antenna induction between the oscillation object and the diagnosis object changes depending on the positional relationship between the electrode of the oscillation object and the electrode of the diagnosis object. Therefore, the fault diagnosis device can diagnose the presence or absence of a fault in the diagnosis object based on a comparison between the level of the voltage measured by the measurement circuit of the diagnosis object and a predetermined reference level, thereby more accurately diagnosing the presence or absence of a fault in the diagnosis object. Furthermore, according to the present invention, by comparing the levels, it may be possible to identify not only the presence or absence of a fault but also the type of fault (e.g., a closed fault).

[0023] (7) The fault diagnosis device diagnoses the presence or absence of a fault in the object to be diagnosed based on the number of occurrences of pulse-like fluctuations in voltage measured by a measurement circuit of the object to be diagnosed, thereby making it possible to diagnose the presence or absence of a chattering fault in the object to be diagnosed.

[0024] (8) In the present invention, by making the oscillation frequency different for each proximity sensor, the frequency of the electromagnetic waves generated from the electrode part of the oscillation target can be changed for each proximity sensor. Therefore, according to the present invention, it is possible to diagnose the presence or absence of a fault in the diagnosis target with even greater accuracy.

[0025] (9) A steering device according to the present invention includes a steering wheel, a proximity sensor system provided on the steering wheel, and a grip determination device that determines whether the steering wheel is being gripped based on detection results from the multiple proximity sensors. Therefore, while a driver is driving a vehicle equipped with the steering device, the grip determination device determines whether the driver is gripping the steering wheel, while the fault diagnosis device diagnoses whether the multiple proximity sensors have a malfunction. This makes it possible to diagnose whether the proximity sensors provided on the steering wheel have a malfunction with a relatively simple configuration, thereby contributing to the development of a sustainable transportation system.

[0026] (10) The fault diagnosis method according to the present invention sets at least two of a plurality of proximity sensors as oscillation targets and diagnosis targets, measures electrical characteristics of the electrodes by a measurement circuit of the diagnosis target while generating electromagnetic waves of an oscillation frequency by a power supply circuit of the oscillation target, and further diagnoses the presence or absence of a fault in the diagnosis target based on the measurement results of the electrical characteristics. Therefore, according to the present invention, since the presence or absence of a fault can be diagnosed using at least two of a plurality of proximity sensors provided in the same target structure, the presence or absence of a fault in the proximity sensors can be diagnosed with a relatively simple configuration, which can contribute to the development of a sustainable transportation system. [Brief description of the drawings]

[0027] [Figure 1] 1 is a diagram showing a configuration of a proximity sensor system and a steering device according to a first embodiment of the present invention. [Diagram 2] FIG. 4 is a diagram showing a circuit configuration of a right sensor circuit. [Diagram 3] 4 is a flowchart showing a specific procedure of a fault diagnosis process. [Figure 4] FIG. 11 is a diagram illustrating an example of a target setting table. [Diagram 5] 4 is a time chart showing transitions of control modes of each proximity sensor; [Figure 6] 10 is a flowchart showing a specific procedure of a fault diagnosis process in a proximity sensor system and a steering device according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] First Embodiment Hereinafter, a proximity sensor system, a steering device, and a fault diagnosis method according to a first embodiment of the present invention will be described with reference to the drawings.

[0029] 1 is a diagram showing the configuration of a proximity sensor system S according to this embodiment and a steering device 1 including, as a component, the proximity sensor system S. The steering device 1 is mounted on a vehicle (not shown).

[0030] The steering device 1 comprises a steering wheel 2 that receives vehicle steering operations and auxiliary operation of vehicle accessories by the driver, a steering shaft 3 that supports the steering wheel 2, a proximity sensor system S that is provided on the steering wheel 2 as a target structure and detects the proximity of a target object (e.g., the driver's hand) to the steering wheel 2, and a grip determination device 9 that determines whether or not the driver is gripping the steering wheel 2 based on the detection result by the proximity sensor system S.

[0031] The steering wheel 2 comprises a circular rim portion 20 which can be gripped by the driver, a hub portion 23 provided on the inside of the rim portion 20, and three spoke portions 25L, 25R, 25D which extend radially from the hub portion 23 and are connected to the rim inner portion 21 of the rim portion 20.

[0032] The hub portion 23 is disk-shaped and is provided, for example, at the center of the rim portion 20 as seen by the driver, constituting the center of the steering wheel 2. A steering shaft 3 that axially supports the steering wheel 2 is connected to the back side of the hub portion 23 as seen by the driver. The steering shaft 3 is an axial connecting member that connects a core metal that is the skeleton of the hub portion 23 to a steering mechanism that constitutes part of the vehicle body (not shown). Therefore, the steering torque generated by the driver rotating the steering wheel 2 is transmitted by this steering shaft 3 to the steering mechanism (not shown).

[0033] The rim portion 20 and the hub portion 23 are connected by three spoke portions 25L, 25R, and 25D. The left spoke portion 25L extends horizontally and connects the left portion of the hub portion 23 as seen by the driver to the left portion of the rim inner circumferential portion 21 as seen by the driver. The right spoke portion 25R extends horizontally and parallel to the left spoke portion 25L and connects the right portion of the hub portion 23 as seen by the driver to the right portion of the rim inner circumferential portion 21 as seen by the driver. The lower spoke portion 25D extends perpendicularly to the spoke portions 25L and 25R and vertically and connects the lower portion of the hub portion 23 as seen by the driver to the lower portion of the rim inner circumferential portion 21 as seen by the driver.

[0034] As described above, the rim portion 20 has a circular shape when viewed from the driver, and the driver can grasp the entire circumference of the rim portion 20.

[0035] The left spoke portion 25L and the right spoke portion 25R are provided with a left accessory operation console unit 27L and a right accessory operation console unit 27R, respectively, that accepts accessory operations by the driver to operate vehicle accessories (not shown, for example, an audio device, a car navigation device, etc.) The driver can operate the vehicle accessories by operating a plurality of switches provided on these accessory operation console units 27L and 27R with his / her fingers.

[0036] In the following description, the positions of the rim portion 20, the rim inner periphery 21, the hub portion 23, and the steering shaft 3, which are substantially circular as viewed by the driver, and the orientations of the spoke portions 25L, 25R, and 25D may be expressed as angles [°] in a clockwise direction with the steering shaft 3 as the center and the upper end portion 201 of the rim portion 20 as viewed by the driver as the reference. That is, the right spoke portion 25R extends along a 90° direction and connects the 90° portions of the hub portion 23 and the rim inner periphery 21. The lower spoke portion 25D extends along a 180° direction and connects the 180° portions of the hub portion 23 and the rim inner periphery 21. The left spoke portion 25L extends along a 270° direction and connects the 270° portions of the hub portion 23 and the rim inner periphery 21.

[0037] The proximity sensor unit S includes a plurality of (four in this embodiment) proximity sensors 4, 5, 6, 7 that detect the proximity of the driver's hands to the steering wheel 2, and a fault diagnosis device 8 that diagnoses the presence or absence of a fault in these proximity sensors 4 to 7. As described below, the proximity sensors 4 to 7 include electrode portions 40, 50, 60, 70 provided at different positions on the steering wheel 2, respectively. Therefore, the detection target area for the proximity of the driver's hands to the steering wheel 2 is different for each of the proximity sensors 4 to 7.

[0038] The upper right proximity sensor 4 includes an upper right electrode portion 40 provided on the steering wheel 2 and an upper right sensor circuit 42 electrically connected to the upper right electrode portion 40. The upper right electrode portion 40 is provided on the right spoke portion 23R of the steering wheel 2, above the right accessory operation console unit 27R as seen from the driver. The upper right electrode portion 40 is a conductive plate, and is provided on the right spoke portion 23R so as to face the 0° to 90° region (hereinafter also referred to as the "upper right grip portion 204") of the rim portion 20. The upper right sensor circuit 42 is connected to the upper right electrode portion 40 via a wiring 41. The upper right sensor circuit 42 has a function of measuring the capacitance between the upper right electrode portion 40 and the ground as a value that increases or decreases according to the distance between the arrangement position of the upper right electrode portion 40 and the human body. The closer the distance between the arrangement position of the upper right electrode portion 40 and the human body, the larger the capacitance between the upper right electrode portion 40 and the ground. The upper right sensor circuit 42 transmits the measurement result of the capacitance to the grip determination device 9.

[0039] The upper left proximity sensor 5 includes an upper left electrode portion 50 provided on the steering wheel 2 and an upper left sensor circuit 52 electrically connected to the upper left electrode portion 50. The upper left electrode portion 50 is provided on the left spoke portion 23L of the steering wheel 2, above the left accessory operation console unit 27L as viewed from the driver. The upper left electrode portion 50 is a conductive plate, and is provided on the left spoke portion 23L so as to face the 270° to 360° region of the rim portion 20 (hereinafter also referred to as the "upper left grip portion 205"). The upper left sensor circuit 52 is connected to the upper left electrode portion 50 via a wiring 51. The upper left sensor circuit 52 has a function of measuring the capacitance between the upper left electrode portion 50 and the ground as a value that increases or decreases according to the distance between the position where the upper left electrode portion 50 is disposed and the human body. The closer the distance between the position where the upper left electrode portion 50 is disposed and the human body, the greater the capacitance between the upper left electrode portion 50 and the ground. The upper left sensor circuit 52 transmits the capacitance measurement result to the gripping determination device 9.

[0040] The lower-right proximity sensor 6 includes a lower-right electrode unit 60 provided on the steering wheel 2 and a lower-right sensor circuit 62 electrically connected to the lower-right electrode unit 60. The lower-right electrode unit 60 is provided on the right spoke unit 23R of the steering wheel 2 below the right accessory operation console unit 27R as viewed from the driver. The lower-right electrode unit 60 is a conductive plate and is provided on the right spoke unit 23R so as to face the 90° to 180° region of the rim unit 20 (hereinafter also referred to as the "lower-right grip unit 206"). The lower-right sensor circuit 62 is connected to the lower-right electrode unit 60 via a wiring 61. The lower-right sensor circuit 62 has a function of measuring the capacitance between the lower-right electrode unit 60 and the ground as a value that increases or decreases according to the distance between the position where the lower-right electrode unit 60 is disposed and the human body. The closer the distance between the position where the lower-right electrode unit 60 is disposed and the human body, the greater the capacitance between the lower-right electrode unit 60 and the ground. The lower right sensor circuit 62 transmits the capacitance measurement result to the grip determination device 9.

[0041] The lower-left proximity sensor 7 includes a lower-left electrode unit 70 provided on the steering wheel 2 and a lower-left sensor circuit 72 electrically connected to the lower-left electrode unit 70. The lower-left electrode unit 70 is provided on the left spoke unit 23L of the steering wheel 2 below the left accessory operation console unit 27L as viewed from the driver. The lower-left electrode unit 70 is a conductive plate and is provided on the left spoke unit 23L so as to face the 180° to 270° region of the rim unit 20 (hereinafter also referred to as the "lower-left grip unit 207"). The lower-left sensor circuit 72 is connected to the lower-left electrode unit 70 via a wiring 71. The lower-left sensor circuit 72 has a function of measuring the capacitance between the lower-left electrode unit 70 and the ground as a value that increases or decreases according to the distance between the position where the lower-left electrode unit 70 is disposed and the human body. The closer the distance between the position where the lower-left electrode unit 70 is disposed and the human body, the greater the capacitance between the lower-left electrode unit 70 and the ground. The lower left sensor circuit 72 transmits the capacitance measurement result to the gripping determination device 9.

[0042] As described above, the electrode parts 40, 50, 60, 70 of the proximity sensors 4, 5, 6, 7 are provided at different positions on the steering wheel 2. Therefore, the detection target areas on the steering wheel 2 are different for each of the proximity sensors 4, 5, 6, 7. More specifically, the upper right proximity sensor 4 detects the upper right grip part 204 of the steering wheel 2 as a detection target area, and detects the approach of the driver's hand to this detection target area. The upper left proximity sensor 5 detects the upper left grip part 205 of the steering wheel 2 as a detection target area, and detects the approach of the driver's hand to this detection target area. The lower right proximity sensor 6 detects the lower right grip part 206 of the steering wheel 2 as a detection target area, and detects the approach of the driver's hand to this detection target area. The lower left proximity sensor 7 detects the lower left grip part 207 of the steering wheel 2 as a detection target area, and detects the approach of the driver's hand to this detection target area.

[0043] FIG. 2 is a diagram showing the circuit configuration of the upper right sensor circuit 42. As shown in FIG.

[0044] The upper right sensor circuit 42 includes a first switch 43 connected to the upper right electrode unit 40 via a wiring 41, a power supply circuit 45 connected to the upper right electrode unit 40 via the wiring 41 and the first switch 43, a measurement circuit 46 connected to the upper right electrode unit 40 via the wiring 41 and the first switch 43, and a control circuit 47 that controls the first switch 43, the power supply circuit 45, and the measurement circuit 46. In Fig. 2, the capacitance between the upper right electrode unit 40 and the ground (e.g., the vehicle body) is illustrated as being divided into a capacitance Ch formed by a human body H including the driver's hands operating the steering wheel 2, and a floating capacitance Ce formed by a floating capacitor E such as wiring and components other than the human body H.

[0045] The first switch 43 is a switching element that is turned on / off in response to a command from the control circuit 47. When the first switch 43 is turned on, it connects the upper right electrode unit 40 to the power supply circuit 45 and disconnects the upper right electrode unit 40 from the measurement circuit 46. When the first switch 43 is turned off, it connects the upper right electrode unit 40 to the measurement circuit 46 and disconnects the upper right electrode unit 40 from the power supply circuit 45. That is, the first switch 43 selectively switches the connection destination of the upper right electrode unit 40 between the power supply circuit 45 and the measurement circuit 46 in response to a command from the control circuit 47.

[0046] The power supply circuit 45 includes a pulse power supply 451 and an amplifier 452 connected in series to the upper right electrode unit 40 via a first switch 43, and uses these to apply a voltage of a predetermined oscillation frequency fa to the upper right electrode unit 40. The pulse power supply 451 supplies a pulse voltage Vs of an oscillation frequency fa and a predetermined voltage to the amplifier 452 in response to a command from the control circuit 47. The amplifier 452 amplifies the pulse voltage Vs of the oscillation frequency fa supplied from the pulse power supply 451, and applies it to the upper right electrode unit 40 via the first switch 43.

[0047] The measurement circuit 46 includes a reference capacitor 461 connected to the upper right electrode unit 40 via the first switch 43, a second switch 462, and a voltage sensor 463, and uses these to measure the electrical characteristics of the upper right electrode unit 40. The reference capacitor 461 is connected to the upper right electrode unit 40 via the first switch 43.

[0048] The second switch 462 is connected in parallel to the reference capacitor 461. The second switch 462 is a switching element that is turned on / off in response to a command from the control circuit 47. When the second switch 462 is turned on, it connects the high potential side of the reference capacitor 461 to the ground and discharges the charge stored in the reference capacitor 461. When the second switch 462 is turned off, it disconnects the high potential side of the reference capacitor 461 from the ground.

[0049] The voltage sensor 463 measures the voltage VCref of the reference capacitor 461, and transmits a signal according to the measurement value to the control circuit 47. Hereinafter, the measurement value of the voltage VCref obtained by the voltage sensor 463 of the upper right proximity sensor 4 is denoted as "VCref_RU".

[0050] The control circuit 47 controls the first switch 43, the power supply circuit 45, and the measurement circuit 46 under a control mode determined by a command from the fault diagnosis device 8 described below. The control circuit 47 has a plurality of control modes determined therein, such as a sensing mode in which the upper right proximity sensor 4 operates as a proximity sensor, and a receiving mode in which the upper right proximity sensor 4 operates as an antenna for receiving electromagnetic waves.

[0051] In the sensing mode, the control circuit 47 controls the first switch 43, the power supply circuit 45, and the measurement circuit 46 in the following procedure, thereby operating the upper right proximity sensor 4 as a proximity sensor.

[0052] More specifically, in the sensing mode, the control circuit 47 turns off the second switch 462 until the measured value VCref_RU of the voltage of the reference capacitor 461 reaches a predetermined threshold value Vthr. After the measured value VCref_RU of the voltage of the reference capacitor 461 reaches the threshold value Vthr, the control circuit 47 turns on the second switch 462 to discharge the charge stored in the reference capacitor 461.

[0053] In the sensing mode, the control circuit 47 turns on the pulse power supply 451 and causes the power supply circuit 45 to generate a voltage with an oscillation frequency fa, while switching the first switch 43 on and off at approximately the same frequency as the oscillation frequency fa.

[0054] More specifically, the control circuit 47 turns on the first switch 43 in response to the rise of the pulse voltage Vs of the pulse power supply 451, thereby establishing electrical continuity between the upper right electrode unit 40 and the power supply circuit 45, and disconnecting the upper right electrode unit 40 from the measurement circuit 46. As a result, the pulse voltage Vs is applied to the upper right electrode unit 40, and electric charge moves through the path indicated by the arrow 2a in FIG. 2, charging the human body H and the floating capacitor E.

[0055] In addition, the control circuit 47 turns off the first switch 43 in response to the falling edge of the pulse voltage Vs of the pulse power supply 451, thereby connecting the upper right electrode unit 40 to the measurement circuit 46 and disconnecting the upper right electrode unit 40 from the power supply circuit 45. This connects the human body H and the floating capacitor E to the reference capacitor 461, and charges move from the human body H and the floating capacitor E to the reference capacitor 461 via the path indicated by the arrow 2b in Fig. 2, charging the reference capacitor 461. This causes the voltage VCref of the reference capacitor 461 to rise.

[0056] When the power supply circuit 45 applies a pulse voltage with an oscillation frequency fa in this way, the human body H and the floating capacitor E are alternately charged and discharged, and the voltage VCref of the reference capacitor 461 gradually increases. At this time, the time until the voltage VCref of the reference capacitor 461 reaches the threshold value Vthr (or the number of pulses of the pulse power supply 461) varies depending on the capacitance Ch formed by the human body H, that is, the distance between the upper right electrode unit 40 and the driver's body. That is, when a part of the driver's body is close to the arrangement position of the upper right electrode unit 40 of the rim unit 20 and the capacitance Ch is high, the time until the voltage VCref of the reference capacitor 461 reaches the threshold value Vthr becomes short, and when a part of the driver's body is far from the arrangement position of the upper right electrode unit 40 and the capacitance Ch is low, the time until the voltage VCref of the reference capacitor 461 reaches the threshold value Vthr becomes long.

[0057] In the sensing mode, the control circuit 47 measures the time and the number of pulses until the measured value VCref_RU of the voltage of the reference capacitor 461 reaches the threshold value Vthr, and based on this measurement result, indirectly measures the capacitance Ch formed by the human body H present in the vicinity of the upper right electrode unit 40, and transmits a signal according to the measurement value to the grip determination device 9. As described above, the control circuit 47 detects the proximity of the human body H to the detection target area of ​​the right proximity sensor 4 through such measurement of the capacitance Ch. Hereinafter, the measurement value of the capacitance Ch obtained by the control circuit 47 will be referred to as "Ch_RU".

[0058] As described above, in the sensing mode, the control circuit 47 connects the upper right electrode unit 40 to the power supply circuit 45 and applies a voltage of the oscillation frequency fa to the upper right electrode unit 40. Therefore, while the right proximity sensor 4 is operating in the sensing mode, an electromagnetic wave of the oscillation frequency fa is generated from the upper right electrode unit 40.

[0059] In addition, in the reception mode, the control circuit 47 maintains the first switch 43 and the second switch 462 in an off state. That is, in the reception mode, the control circuit 47 cuts off the connection between the upper right electrode unit 40 and the power supply circuit 45, and maintains the upper right electrode unit 40 in a connected state with the measurement circuit 46. In addition, in the reception mode, the control circuit 47 transmits to the fault diagnosis device 8 a signal corresponding to the measurement result of the electrical characteristic of the upper right electrode unit 40 by the measurement circuit 46, that is, the measured value VCref_RU of the voltage of the reference capacitor 461, while maintaining the upper right electrode unit 40 in a connected state with the measurement circuit 46.

[0060] As described above, in the reception mode, the control circuit 47 maintains the connection between the upper right electrode unit 40 and the power supply circuit 45 in a cut-off state, and therefore cannot detect the proximity of the human body H to the upper right electrode unit 40.

[0061] The circuit configurations of the upper left sensor circuit 52, the lower right sensor circuit 62, and the lower left sensor circuit 72 are substantially the same as the circuit configuration of the upper right sensor circuit 42, except for the oscillation frequency of the pulsed power supply. Therefore, detailed explanations and illustrations of the circuit configurations of the upper left sensor circuit 52, the lower right sensor circuit 62, and the lower left sensor circuit 72 will be omitted below.

[0062] In the following, the oscillation frequency of the pulsed power supply of the upper left sensor circuit 52 is denoted as "fb", the oscillation frequency of the pulsed power supply of the lower right sensor circuit 62 is denoted as "fc", and the oscillation frequency of the pulsed power supply of the lower left sensor circuit 72 is denoted as "fd". Note that in the following, a case will be described in which the oscillation frequencies fa, fb, fc, and fd of the proximity sensors 4, 5, 6, and 7 are different, but the present invention is not limited to this. The oscillation frequencies fa to fd may be the same for each of the proximity sensors 4 to 7. Furthermore, these oscillation frequencies fa to fd are set to, for example, about several tens of kHz.

[0063] In the following, the measured voltage value of the reference capacitor of the upper left sensor circuit 52 is denoted as "VCref_LU", the measured voltage value of the reference capacitor of the lower right sensor circuit 62 is denoted as "VCref_RL", and the measured voltage value of the reference capacitor of the lower left sensor circuit 72 is denoted as "VCref_LL".

[0064] In the following, the capacitance measurement value obtained by the control circuit of the upper left sensor circuit 52 will be denoted as "Ch_LU", the capacitance measurement value obtained by the control circuit of the lower right sensor circuit 62 will be denoted as "Ch_RL", and the capacitance measurement value obtained by the control circuit of the lower left sensor circuit 72 will be denoted as "Ch_LL".

[0065] In addition, like the above-mentioned upper right proximity sensor 4, the upper left proximity sensor 5, the lower right proximity sensor 6, and the lower left proximity sensor 7 are all capable of switching the control mode between the sensing mode and the receiving mode in response to a command from the fault diagnosis device 8.

[0066] The grip determination device 9 determines whether or not the driver is gripping the steering wheel 2 based on a comparison of the detection results of each proximity sensor 4-7, i.e., the capacitance measurement values ​​Ch_RU, Ch_LU, Ch_RL, and Ch_LL obtained by operating each proximity sensor 4-7 in sensing mode, with predetermined grip determination thresholds Ch_RU_th, Ch_LU_th, Ch_RL_th, and Ch_LL_th.

[0067] More specifically, if the measurement value Ch_RU is greater than the grip determination threshold value Ch_RU_th, the grip determination device 9 determines that the steering wheel 2 is being gripped at the upper right grip portion 204, and if the measurement value Ch_RU is equal to or less than the grip determination threshold value Ch_RU_th, it determines that the steering wheel 2 is not being gripped at the upper right grip portion 204.

[0068] In addition, if the measurement value Ch_LU is greater than the grip determination threshold value Ch_LU_th, the grip determination device 9 determines that the steering handle 2 is being gripped at the upper left grip portion 205, and if the measurement value Ch_LU is equal to or less than the grip determination threshold value Ch_LU_th, it determines that the steering handle 2 is not being gripped at the upper left grip portion 205.

[0069] In addition, if the measurement value Ch_RL is greater than the grip determination threshold value Ch_RL_th, the grip determination device 9 determines that the steering handle 2 is being gripped at the lower right grip portion 206, and if the measurement value Ch_RL is equal to or less than the grip determination threshold value Ch_RL_th, it determines that the steering handle 2 is not being gripped at the lower right grip portion 206.

[0070] In addition, if the measurement value Ch_LL is greater than the grip determination threshold value Ch_LL_th, the grip determination device 9 determines that the steering handle 2 is being gripped at the lower left grip portion 207, and if the measurement value Ch_LL is equal to or less than the grip determination threshold value Ch_LL_th, it determines that the steering handle 2 is not being gripped at the lower left grip portion 207.

[0071] When any of the proximity sensors 4 to 7 is diagnosed as faulty by the fault diagnosis device 8, the grip determination device 9 cancels the determination result based on the detection result of the proximity sensor diagnosed as faulty.

[0072] Fault diagnosis device 8 diagnoses whether or not the proximity sensors 4 to 7 have a fault by executing a fault diagnosis process which will be described with reference to FIG.

[0073] 3 is a flowchart showing a specific procedure of the fault diagnosis process. The fault diagnosis device 8 repeatedly executes the fault diagnosis process shown in FIG. 3 in response to starting of the vehicle on which the steering device 1 is mounted.

[0074] First, in step ST1, the fault diagnosis device 8 counts up the number of turns N, and then proceeds to step ST2. Here, the number of turns N corresponds to the number of times the fault diagnosis process consisting of the processes of steps ST2 to ST6 described below is executed, and the initial value is set to 0.

[0075] Next, in step ST2, the fault diagnosis device 8 sets at least two of the multiple proximity sensors 4-7 as new oscillation targets and diagnosis targets, and proceeds to step ST3. In the following, the fault diagnosis device 8 sets one selected from the multiple proximity sensors 4-7 as the oscillation target, and sets all of the multiple proximity sensors 4-7 except the oscillation target as diagnosis targets, but the present invention is not limited to this. In other words, it is sufficient that at least one each of the multiple proximity sensors 4-7 is set as the oscillation target and diagnosis target, and the number of sensors set is arbitrary.

[0076] In this embodiment, the fault diagnosis device 8 sets an oscillation target and a diagnosis target by searching a target setting table as exemplified in FIG.

[0077] According to the target setting table shown in Fig. 4, the oscillation target is set cyclically in the order of the upper right proximity sensor 4, the upper left proximity sensor 5, the lower right proximity sensor 6, and the lower left proximity sensor 7 each time the number of turns N increases. In addition, all of the multiple proximity sensors 4 to 7 except for the oscillation target are set as diagnosis targets. Therefore, when the number of turns N is "1", according to the target setting table in Fig. 4, the upper right proximity sensor 4 is set as the oscillation target, and the upper left proximity sensor 5, the lower right proximity sensor 6, and the lower left proximity sensor 7 are set as diagnosis targets.

[0078] Next, in step ST3, the fault diagnosis device 8 sets the control mode of the proximity sensor that was selected as the oscillation target in step ST2 to the sensing mode, sets the control mode of the proximity sensor that was selected as the diagnosis target to the receiving mode, and proceeds to step ST4. By setting the control mode of the oscillation target to the sensing mode as described above, the oscillation target can be used as a proximity sensor while generating electromagnetic waves of an oscillation frequency from the electrode portion of the oscillation target. Also, by setting the control mode of the diagnosis target to the receiving mode, the diagnosis target can be operated as an antenna to receive electromagnetic waves generated from the oscillation target.

[0079] Next, in step ST4, fault diagnosis device 8 obtains the measurement result by the measurement circuit of the diagnosis target, that is, the measured value of the voltage of the reference capacitor of the diagnosis target (hereinafter referred to as the "measured voltage value"), and proceeds to step ST5.

[0080] In step ST5, the fault diagnosis device 8 judges whether or not the diagnosis time corresponding to the time elapsed since the control modes of the oscillation target and the diagnosis target were set to the sensing mode and the receiving mode for the first time in step ST3, respectively, exceeds a predetermined set time. Here, the set time is set to a time sufficiently longer than the period (i.e., the reciprocal of the oscillation frequency) of the pulse voltage generated by the pulse power supply of the oscillation target. However, as described above, the diagnosis target set to the receiving mode cannot detect the proximity of an object to the electrode part. For this reason, the set time is set within a range equal to or less than a predetermined upper limit time. More specifically, this set time is set to, for example, about several hundred [ms]. If the judgment result of step ST5 is NO, the fault diagnosis device 8 returns to step ST3, and if the judgment result is YES, the fault diagnosis device 8 proceeds to step ST6. As described above, after the fault diagnosis device 8 sets a new oscillation target and diagnosis target, the voltage of the reference capacitor is measured by the measurement circuit of the diagnosis target while the power supply circuit of the oscillation target generates electromagnetic waves of the oscillation frequency from the electrode part for the set time.

[0081] Next, in step ST6, the fault diagnosis device 8 diagnoses the presence or absence of a fault in each diagnosis target based on the time-series data of the voltage measurement values ​​of each diagnosis device obtained by repeatedly executing the processes of steps ST3 and ST4 for a set time, and returns to the process of step ST2. That is, after diagnosing the presence or absence of a fault in each diagnosis target, the fault diagnosis device 8 returns to step ST1 and starts the fault diagnosis process for the next turn.

[0082] More specifically, the fault diagnosis device 8 calculates the voltage frequency, average level, and number of occurrences of pulse-like fluctuations for each diagnosis target based on the time-series data of the voltage measurement values ​​obtained by the processes of steps ST3 and ST4. Furthermore, the fault diagnosis device 8 diagnoses the presence or absence of a fault in each diagnosis target according to the procedure described below based on the frequency, average level, and number of occurrences of pulse-like fluctuations calculated based on the voltage measurement values.

[0083] First, the fault diagnosis device 8 compares the frequency calculated based on the voltage measurement value with the oscillation frequency of the pulse power supply of the oscillation target to determine for each diagnosis target whether or not the electromagnetic waves of the oscillation frequency generated from the oscillation target have been received. More specifically, if the absolute value of the difference between the frequency calculated based on the voltage measurement value and the oscillation frequency of the oscillation target is less than a predetermined value, the fault diagnosis device 8 determines that the electromagnetic waves generated from the oscillation target have been received, and if the absolute value of the difference is equal to or greater than a predetermined value, the fault diagnosis device 8 determines that the electromagnetic waves generated from the oscillation target have not been received. If the fault diagnosis device 8 determines that the electromagnetic waves generated from the oscillation target have not been received, it determines that the diagnosis target has a fault (more specifically, a so-called open fault in which a disconnection occurs in the circuit of the diagnosis target due to peeling of a conductive pattern or deterioration or destruction of a switching element).

[0084] Next, when the fault diagnosis device 8 judges that the electromagnetic waves of the oscillation frequency generated from the oscillation target can be received by the above procedure, it compares the average level of the voltage calculated based on the voltage measurement value with a predetermined reference level to judge for each diagnosis target whether the electromagnetic waves of the oscillation frequency generated from the oscillation target can be received with appropriate sensitivity. More specifically, when the difference between the average level of the voltage calculated based on the voltage measurement value and the reference level is less than a predetermined level, the fault diagnosis device 8 judges that the electromagnetic waves generated from the oscillation target can be received with appropriate sensitivity and judges that the diagnosis target is normal (i.e., not broken). When the difference between the average level of the voltage calculated based on the voltage measurement value and the reference level is equal to or greater than a predetermined level, the fault diagnosis device 8 judges that the electromagnetic waves generated from the oscillation target cannot be received with appropriate sensitivity. When the fault diagnosis device 8 judges that the electromagnetic waves generated from the oscillation target cannot be received with appropriate sensitivity, it judges that the diagnosis target has a fault (more specifically, a so-called closed fault in which a short circuit occurs in the circuit of the diagnosis target due to the intrusion of a foreign object or deterioration or destruction of a switching element).

[0085] Here, the average level of the voltage when the electromagnetic waves generated from the oscillation target are received by the diagnosis target varies depending on the distance between the oscillation target and the diagnosis target, the presence or absence of obstacles, etc. For this reason, the above-mentioned reference level is determined for each combination of the oscillation target and the diagnosis target.

[0086] Next, when the fault diagnosis device 8 judges that the electromagnetic wave of the oscillation frequency generated from the oscillation target can be received with an appropriate sensitivity by the above procedure, it judges whether or not a chattering fault has occurred in the switching element (particularly, the first switch) included in the diagnosis target for each diagnosis target by comparing the number of occurrences of the pulse-like fluctuation calculated based on the voltage measurement value with a predetermined number threshold. Here, the chattering fault refers to a phenomenon in which the switching element intermittently repeats a conductive state and a cut-off state against intention for a predetermined time when the switching element is switched on / off. More specifically, when the number of occurrences of the pulse-like fluctuation calculated based on the voltage measurement value is less than the number threshold, the fault diagnosis device 8 judges that the chattering fault has not occurred in the diagnosis target. Also, when the number of occurrences of the pulse-like fluctuation calculated based on the voltage measurement value is equal to or greater than the number threshold, the fault diagnosis device 8 judges that the chattering fault has occurred in the diagnosis target.

[0087] Furthermore, the fault diagnosis device 8 transmits information on the diagnosis results for each diagnosis target obtained by the above procedure to the grip determination device 9.

[0088] FIG. 5 is a time chart showing the transition of the control mode of each of the proximity sensors 4 to 7 when the oscillation target and the diagnosis target are set based on the target setting table shown in FIG.

[0089] In the fault diagnosis process shown in FIG. 3, the fault diagnosis device 8 periodically switches the settings of the oscillation target and the diagnosis target at every set time. Therefore, as shown in FIG. 5, the control mode of each of the proximity sensors 4 to 7 also periodically switches between the sensing mode and the receiving mode at every set time. Also, as described above, while the control mode of the proximity sensor is set to the receiving mode, this proximity sensor cannot detect the proximity of a human body to the steering wheel 2. However, by setting the oscillation target and the diagnosis target based on the target setting table as shown in FIG. 4, the control mode of each proximity sensor can be periodically set to the sensing mode every four turns as shown in FIG. 5, so that the proximity sensors 4 to 7 can diagnose a fault in each proximity sensor while monitoring whether the steering wheel 2 is being properly gripped by the driver.

[0090] The proximity sensor system S and the steering device 1 according to this embodiment provide the following advantages.

[0091] (1) The proximity sensor system S includes a plurality of proximity sensors 4-7 that detect the proximity of a human body H to the steering wheel 2, and a fault diagnosis device 8 that diagnoses the presence or absence of a fault in these proximity sensors 4-7. Each of the proximity sensors 4-7 includes an electrode portion provided at a different position on the steering wheel 2, a power supply circuit 45 that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit that measures the electrical characteristics of the electrode portion. The fault diagnosis device 8 sets at least two of the plurality of proximity sensors 4-7 as an oscillation target and a diagnosis target. The fault diagnosis device 8 also acquires a measurement result of the electrical characteristics of the diagnosis target by the measurement circuit while an electromagnetic wave of an oscillation frequency is generated from the electrode portion by the power supply circuit of the oscillation target, and diagnoses the presence or absence of a fault in the diagnosis target based on the measurement result. Here, when a voltage of an oscillation frequency is applied to the electrode portion by the power supply circuit of the oscillation target, an electromagnetic wave of the oscillation frequency is generated around the electrode portion. At this time, if there is no fault in the diagnosis target, the electrical characteristics of the electrode portion of the diagnosis target change due to the antenna induction effect between the oscillation target and the diagnosis target. Therefore, the presence or absence of a fault in the diagnostic target correlates with the measurement results of the diagnostic target's measurement circuit. Therefore, according to this embodiment, the presence or absence of a fault can be diagnosed using at least two of the multiple proximity sensors 4-7 provided on the same steering wheel 2, so that the presence or absence of a fault in each of the proximity sensors 4-7 can be diagnosed with a relatively simple configuration, which can contribute to the development of a sustainable transportation system.

[0092] (2) While the oscillation target is generating electromagnetic waves, the fault diagnosis device 8 cuts off the connection between the electrode part of the diagnosis target and the power supply circuit and maintains the connection between the electrode part of the diagnosis target and the measurement circuit. Therefore, according to this embodiment, it is possible to prevent the electrical characteristics of the electrode part of the diagnosis target from fluctuating due to the influence of the voltage applied from the power supply circuit of the diagnosis target, and therefore it is possible to accurately diagnose the presence or absence of a fault in the diagnosis target.

[0093] (3) The fault diagnosis device 8 periodically switches the settings of the oscillation target and diagnosis target at predetermined set times. As a result, according to this embodiment, even if many proximity sensors 4-7 are provided on the steering wheel 2, it is possible to periodically diagnose the presence or absence of faults in all of these proximity sensors 4-7.

[0094] (4) As described above, when a voltage of the oscillation frequency is applied to the electrode part by the power supply circuit of the oscillation target, electromagnetic waves of the oscillation frequency are generated around this electrode part. At this time, if there is no fault in the diagnosis target, the voltage of the reference capacitor connected to the electrode part of the diagnosis target fluctuates at the same frequency as the oscillation frequency of the oscillation target due to the antenna induction effect between the oscillation target and the diagnosis target. Therefore, the fault diagnosis device 8 diagnoses the presence or absence of a fault in the diagnosis target based on a comparison between the frequency of the voltage of the reference capacitor measured by the measurement circuit of the diagnosis target and the oscillation frequency of the power supply circuit of the oscillation target. This makes it possible to diagnose the presence or absence of a fault in the diagnosis target with high accuracy.

[0095] (5) The voltage level of the reference capacitor connected to the electrode of the diagnosis object due to the antenna induction between the oscillation object and the diagnosis object changes depending on the positional relationship between the electrode of the oscillation object and the electrode of the diagnosis object. Therefore, the fault diagnosis device 8 can diagnose the presence or absence of a fault in the diagnosis object based on a comparison between the level of the voltage measured by the measurement circuit of the diagnosis object and a predetermined reference level, thereby more accurately diagnosing the presence or absence of a fault in the diagnosis object. Furthermore, according to this embodiment, by comparing the frequencies, it may be possible to identify not only the presence or absence of a fault but also the type of the fault (e.g., an open fault).

[0096] (6) In this embodiment, by making the oscillation frequency different for each proximity sensor, the frequency of the electromagnetic waves generated from the electrode part of the oscillation target can be changed for each proximity sensor. Therefore, according to this embodiment, it is possible to diagnose the presence or absence of a fault in the diagnosis target with greater accuracy. Also, according to this embodiment, by comparing the levels, it may be possible to identify not only the presence or absence of a fault but also the type of fault (for example, a closed fault).

[0097] (7) Fault diagnosis device 8 diagnoses the presence or absence of a fault in the object to be diagnosed based on the number of occurrences of pulse-like fluctuations in the voltage measured by the measurement circuit of the object to be diagnosed. This makes it possible to diagnose the presence or absence of a chattering fault in the object to be diagnosed.

[0098] (8) The steering device 1 includes a steering wheel 2, a proximity sensor system S provided on the steering wheel 2, and a grip determination device 9 that determines whether the steering wheel 2 is being gripped based on the detection results of the multiple proximity sensors 4 to 7. Therefore, according to this embodiment, while the driver is driving the vehicle equipped with the steering device 1, the grip determination device 9 determines whether the driver is gripping the steering wheel 2, while the fault diagnosis device 8 diagnoses whether the multiple proximity sensors 4 to 7 have a malfunction. Therefore, the proximity sensors 4 to 7 provided on the steering wheel 2 can be diagnosed with a relatively simple configuration, which can contribute to the development of a sustainable transportation system.

[0099] <Second embodiment> Next, a proximity sensor system, a steering device, and a fault diagnosis method according to a second embodiment of the present invention will be described with reference to the drawings. Note that the mechanical configurations of the proximity sensor system and steering device according to this embodiment are almost the same as the mechanical configurations of the proximity sensor system S and steering device 1 according to the first embodiment, so they are denoted by the same reference numerals and illustrations and detailed descriptions are omitted.

[0100] Fig. 6 is a flowchart showing a specific procedure of the fault diagnosis process by the fault diagnosis device according to this embodiment. In the flowchart shown in Fig. 6, the processes in steps ST11 and ST16 to ST19 are the same as the processes in steps ST1 and ST3 to ST6 in the flowchart of Fig. 3, respectively, and therefore detailed explanations are omitted.

[0101] In step ST12, the failure diagnosis device acquires the grip determination result by the grip determination device (that is, whether or not the steering wheel is being gripped by the driver, and the grip position, etc.), and then proceeds to step ST13.

[0102] Next, in step ST13, the fault diagnosis device refers to the determination result acquired in step ST12 and determines whether or not the steering wheel is being gripped by the driver. If the determination result in step ST13 is YES, the fault diagnosis device proceeds to step ST14, and if the determination result is NO, the fault diagnosis device proceeds to step ST15.

[0103] In step ST15, the fault diagnosis device sets at least two of the plurality of proximity sensors 4 to 7 as new oscillation targets and diagnosis targets based on the grip determination result acquired in step ST12, and proceeds to step ST16.

[0104] More specifically, the fault diagnosis device identifies the proximity sensor that detects the proximity of the human body, that is, the proximity sensor that has the grip position as the detection target area, by referring to the grip determination result. The fault diagnosis device also determines the oscillation target from among the multiple proximity sensors 4 to 7 that detect the proximity of the human body, and determines the diagnosis target from among the multiple proximity sensors that do not detect the proximity of the human body. In this embodiment, the fault diagnosis device sets all of the multiple proximity sensors 4 to 7 that detect the proximity of the human body as the oscillation target, and all of the proximity sensors that do not detect the proximity of the human body as the diagnosis target, but the present invention is not limited to this. For example, only one selected from the sensors that detect the proximity of the human body may be set as the oscillation target, or only one selected from the sensors that do not detect the proximity of the human body may be set as the diagnosis target.

[0105] In step ST15, the fault diagnosis device sets at least two of the multiple proximity sensors 4 to 7 as new oscillation targets and diagnosis targets by the same procedure as in step ST2 (see FIG. 3), and proceeds to step ST16. That is, the fault diagnosis device sets the oscillation targets and diagnosis targets by searching a target setting table as shown in FIG. 4 based on the number of turns N, for example.

[0106] In addition to the above advantages (1) to (8), the proximity sensor system and steering device according to this embodiment have the following advantages.

[0107] (9) In the proximity sensors 4 to 7, in order to detect whether the human body H is approaching the steering wheel 2, it is necessary to apply a voltage to the electrode portion by the power supply circuit as appropriate. In contrast, in order to accurately diagnose the presence or absence of a malfunction of the proximity sensor determined as the diagnosis target as described above, it is preferable to maintain the connection between the electrode portion and the power supply circuit in a cut-off state. In other words, the proximity sensor cannot detect the presence or absence of the human body H while it is determined as the diagnosis target. Therefore, the fault diagnosis device according to this embodiment determines an oscillation target from among the multiple proximity sensors 4 to 7 that detect the proximity of the human body H, and determines a diagnosis target from among those that do not detect the proximity of the human body H. As a result, the proximity sensor determined as the oscillation target can continue to detect the presence or absence of the human body H approaching, while simultaneously diagnosing the presence or absence of a malfunction of the proximity sensor determined as the diagnosis target.

[0108] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and the detailed configuration may be appropriately changed within the scope of the spirit of the present invention.

[0109] For example, in the first embodiment, a case has been described in which at least two of the four proximity sensors 4 to 7 provided on the steering wheel 4 are set as oscillation targets and diagnosis targets, but the present invention is not limited thereto. For example, in the example shown in Fig. 1, the upper right electrode unit 40 and the lower right electrode unit 60 are provided at positions slightly away from the upper left electrode unit 50 and the lower left electrode unit 70. Therefore, when the upper right proximity sensor 4 is set as an oscillation target and the lower left proximity sensor 7 is set as a diagnosis target, the electromagnetic waves generated by the upper right electrode unit 40 of the upper right proximity sensor 4 cannot be received at a sufficient level by the lower left electrode unit 70 of the lower left proximity sensor 7, and it may not be possible to properly diagnose the presence or absence of a malfunction of the diagnosis target.

[0110] Therefore, the fault diagnosis device may divide the four proximity sensors 4 to 7 into a group consisting of the upper right proximity sensor 4 and the lower right proximity sensor 6, and a group consisting of the upper left proximity sensor 5 and the lower left proximity sensor 7, set one oscillation target and one diagnosis target in each group, and perform fault diagnosis processing independently for each group.

[0111] For example, in the above embodiment, the electrode portions 40-70 of the proximity sensors 4-7 are provided on the spoke portions 25L, 25R, but the present invention is not limited to this. Some or all of the electrode portions may be provided on the rim portion 20 or the hub portion 23. In the above embodiment, the number of proximity sensors provided on the steering wheel is four, but the present invention is not limited to this. The number of proximity sensors provided on the steering wheel may be any number equal to or greater than two. [Explanation of symbols]

[0112] 1...Steering device 2. Steering handle 20…Rim section 23…Hub section 25L, 25R, 25D…Spoke section S...Proximity sensor system 4...Upper right proximity sensor (proximity sensor) 40...Top right electrode part (electrode part) 42…Upper right sensor circuit 43…1st switch (switch) 45…Power circuit 46…Measurement circuit 461...Reference capacitor (capacitor) 47...Control circuit 5...Upper left proximity sensor (proximity sensor) 50...Top left electrode part (electrode part) 52…Upper left sensor circuit 6...Bottom right proximity sensor (proximity sensor) 60…Lower right electrode part (electrode part) 62…Lower right sensor circuit 7...Lower left proximity sensor (proximity sensor) 70…Lower left electrode part (electrode part) 72…Lower left sensor circuit 8. Fault diagnosis device 9...Grip determination device

Claims

1. A steering wheel as a target structure that receives steering operation by a driver, a plurality of proximity sensors provided on the target structure and configured to detect the proximity of a target object to the target structure; A proximity sensor system comprising: a fault diagnosis device for diagnosing whether or not the proximity sensor is faulty, Each of the plurality of proximity sensors includes an electrode portion provided at a different position of the target structure, a power supply circuit that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit that measures an electrical characteristic of the electrode portion; The proximity sensor system is characterized in that the fault diagnosis device sets at least two of the multiple proximity sensors as oscillation targets and diagnosis targets, obtains measurement results of the electrical characteristics of the diagnosis target by the measurement circuit while the power supply circuit of the oscillation target generates electromagnetic waves at the oscillation frequency, and diagnoses the presence or absence of a fault in the diagnosis target based on the measurement results.

2. The proximity sensor system described in claim 1, characterized in that the fault diagnosis device disconnects the electrode portion of the diagnosis object from the power supply circuit and maintains the electrode portion and the measurement circuit in a connected state while electromagnetic waves are generated by the oscillation object.

3. The proximity sensor system according to claim 2, characterized in that the fault diagnosis device determines the oscillation target from among the multiple proximity sensors in which the proximity of the target object is detected, and determines the diagnosis target from among those in which the proximity of the target object is not detected.

4. The proximity sensor system according to claim 2 , wherein the fault diagnosis device switches settings of the oscillation target and the diagnosis target at a predetermined cycle.

5. The measurement circuit measures a voltage of a capacitor connected to the electrode portion via a switch, The proximity sensor system described in claim 3 or 4, characterized in that the fault diagnosis device diagnoses the presence or absence of a fault in the object to be diagnosed based on a comparison between the frequency of the voltage measured by the measurement circuit of the object to be diagnosed and the oscillation frequency of the power supply circuit of the oscillation object.

6. The proximity sensor system according to claim 5 , wherein the fault diagnosis device diagnoses the presence or absence of a fault in the object to be diagnosed based on a comparison between a level of a voltage measured by the object to be diagnosed and a predetermined reference level.

7. 7. The proximity sensor system according to claim 6, wherein the fault diagnosis device diagnoses the presence or absence of a fault in the diagnostic object based on the number of occurrences of pulse-like fluctuations in voltage measured by the diagnostic object.

8. 5. The proximity sensor system according to claim 3, wherein the oscillation frequency differs for each proximity sensor.

9. A proximity sensor system according to any one of claims 1 to 4; a grip determination device that determines whether or not the steering handle is being gripped based on a detection result of the proximity sensor.

10. A fault diagnosis method for diagnosing the presence or absence of a fault in a plurality of proximity sensors that detect the proximity of a target object to a steering wheel as a target structure that accepts steering operations by a driver, comprising: Each of the plurality of proximity sensors includes an electrode portion provided at a different position of the target structure, a power supply circuit that applies a voltage of an oscillation frequency to the electrode portion, and a measurement circuit that measures an electrical characteristic of the electrode portion; A first step of setting at least two of the plurality of proximity sensors as oscillation targets and diagnosis targets; a second step of measuring electrical characteristics of the electrode portion by the measurement circuit of the diagnosis target while generating electromagnetic waves of the oscillation frequency by the power supply circuit of the oscillation target; a third step of diagnosing whether or not there is a fault in the object to be diagnosed based on the measurement result in the second step.

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