Grip detection device, failure determination method, and program

Abstract

A grip detection device according to one embodiment of the present invention is a grip detection device (1) for a steering wheel (2) provided with a core rod (23), a shield electrode (22) provided on the outside of the core rod (23) with an insulator (In) interposed therebetween, and a sensor electrode (21) provided further on the outside of the shield electrode (22) with an insulator (In) interposed therebetween, the grip detection device being provided with a control unit (11) for controlling the grip detection device (1). The control unit (11) acquires the capacitance value of the sensor electrode (21) in a state in which the shield electrode (22) and the core rod (23) are short-circuited, and determines the presence or absence of a fault on the basis of the capacitance value.

Description

Technical Field

[0001] The invention relates to a grip detection device, a fault judgment method and a program. Background Art

[0002] There is disclosed a steering wheel unit that can determine whether a capacitance sensor for detecting the grip of a steering wheel has failed (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Document 1: Japanese Patent Publication No. 2019-23011 Summary of the invention

[0005] Problem that the invention aims to solve

[0006] The steering wheel unit described in Patent Document 1 can determine a malfunction of the electrostatic capacitance sensor only when the steering wheel is not being held, but cannot determine a malfunction of the electrostatic capacitance sensor when the steering wheel is being held.

[0007] The present invention has been completed in view of the above situation, and its object is to provide a holding detection device that can determine a fault in any situation regardless of whether the steering wheel is held or not.

[0008] Solutions to the problem

[0009] A holding detection device according to one embodiment of the present invention is a holding detection device (1) for a steering wheel (2), wherein the steering wheel (2) comprises a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) via an insulator (In), and a sensor electrode (21) arranged on the further outside of the shielding electrode (22) via an insulator (In), wherein the holding detection device (1) comprises a control unit (11), wherein the control unit (11) obtains an electrostatic capacitance value of the sensor electrode (21) when the shielding electrode (22) and the core rod (23) are short-circuited, and determines whether there is a fault based on the electrostatic capacitance value.

[0010] A holding detection device according to one embodiment of the present invention comprises a first switch (13a), wherein the first switch (13a) is arranged between the shielding electrode (22) and the core rod (23), and by opening the switch, the shielding electrode (22) and the core rod (23) are short-circuited, and the control unit (11) determines whether there is a fault when the first switch (13a) is opened.

[0011] In a gripping detection device according to one embodiment of the present invention, when the acquired electrostatic capacitance value is smaller than a predetermined value, the control unit (11) determines that it is in a fault state.

[0012] A gripping detection device according to one embodiment of the present invention comprises an additional circuit (132), which is connected to the shielding electrode (22), applies a voltage to the shielding electrode (22), and measures the voltage value of the applied voltage. When the voltage value of the voltage applied by the additional circuit (132) is lower than a specified value, the control unit (11) determines that it is a fault state in which the shielding electrode (22) and the core rod (23) are short-circuited.

[0013] A holding detection device according to one embodiment of the present invention comprises a second switch (13b), wherein the second switch (13b) is arranged between the shielding electrode (22) and the additional circuit (132). By turning on the switch, the shielding electrode (22) and the additional circuit (132) can be energized. When the second switch (13b) is turned on, the control unit (11) determines whether the shielding electrode (22) and the core rod (23) are in a short-circuit state.

[0014] In a gripping detection device according to an embodiment of the present invention, the control unit (11) determines whether the steering wheel (2) is being gripped when the second switch (13b) is turned on.

[0015] A fault judgment method according to one embodiment of the present invention is a fault judgment method for a grip detection device (1) of a steering wheel (2), wherein the steering wheel (2) comprises a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) separated by an insulator (In), and a sensor electrode (21) arranged on the further outside of the shielding electrode (22) separated by an insulator (In), wherein the method obtains the electrostatic capacitance value of the sensor electrode (21) when the shielding electrode (22) and the core rod (23) are short-circuited, and judges whether there is a fault based on the electrostatic capacitance value.

[0016] A program involved in one embodiment of the present invention is a program for performing fault judgment on a grip detection device (1) of a steering wheel (2), wherein the steering wheel (2) includes a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) separated by an insulator (In), and a sensor electrode (21) arranged on the further outside of the shielding electrode (22) separated by an insulator (In). When the shielding electrode (22) and the core rod (23) are short-circuited, the electrostatic capacitance value of the sensor electrode (21) is obtained, and the presence or absence of a fault is judged based on the electrostatic capacitance value.

[0017] Effects of the Invention

[0018] A grip detection device according to an embodiment of the present invention can detect a fault regardless of whether the steering wheel is being gripped or not. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 : is a block diagram showing a configuration example of a steering wheel device according to the present embodiment.

[0020] Figure 2 This is a front view showing a steering wheel of the steering wheel device according to the present embodiment.

[0021] Figure 3 is along Figure 2 A cross-sectional view of the rim portion of the steering wheel taken along line III-III.

[0022] Figure 4 1 is an explanatory diagram showing a specific connection example of a capacitance measurement circuit and the like.

[0023] Figure 5 This is a table showing the electrostatic capacitance value acquired by the electrostatic capacitance sensor in each failure mode when the first switch is opened.

[0024] Figure 6 : is a flowchart showing an example of a processing procedure of the control section. DETAILED DESCRIPTION

[0025] (Implementation Method)

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0027] Figure 1 1 is a block diagram showing a configuration example of a steering wheel device 100 according to the present embodiment. The steering wheel device 100 includes a grip detection ECU (Electronic Control Unit) 1, a steering wheel 2, etc. The grip detection ECU 1 corresponds to a grip detection device. The grip detection ECU 1 is connected to a vehicle-mounted device such as a driving assistance ECU 6 via an in-vehicle network provided in the vehicle.

[0028] Figure 2 1 is a front view showing a steering wheel 2 of a steering wheel device 100 according to the present embodiment. The steering wheel 2 includes an annular rim portion 3 and a hub portion 4 located in the center of the rim portion 3. An airbag (not shown) is built into the hub portion 4. The hub portion 4 is connected to the rim portion 3 via three spoke portions 5.

[0029] The rim 3 is covered with a cover layer 24 such as leather, and the hub 4 and spokes 5 are covered with, for example, a resin member. The rim 3 is not limited to a ring shape, and may be non-circular, such as a D-shape or a C-shape.

[0030] On the inner side of the rim portion 3, a sensor electrode 21 is provided along the circumferential direction of the rim portion 3. The rim portion 3 is divided into three equal parts along the circumferential direction, and a sensor electrode 21 is provided on the inner side of each equal part. The number of sensor electrodes 21 is not limited to three, and may be two or less, or four or more. The sensor electrode 21 forms a capacitor with the shielding electrode 22 described later and / or with the human body in contact with the steering wheel 2, and the size of the electrostatic capacitance (electrostatic capacitance value) that changes according to whether the human body is in contact with the steering wheel 2 is detected by the electrostatic capacitance sensor 131 described later.

[0031] Figure 3 is along Figure 2 2 is a cross-sectional view of the rim 3 of the steering wheel 2 taken along line III-III in FIG. A core rod 23 is provided at the center of the rim 3. A shield electrode 22 is provided around the core rod 23 via an insulator In. A sensor electrode 21 is provided further around the shield electrode 22 via an insulator In. The outer side of the sensor electrode 21 is covered with a covering layer 24 such as leather.

[0032] like Figure 1 As shown, the grip detection ECU1 includes a control unit 11 , a storage unit 12 , a capacitance measurement circuit 13 and a communication unit 14 .

[0033] The control unit 11 is, for example, a microcontroller having a processor using one or more CPUs (Central Processing Units), GPUs (Graphics Processing Units), etc. The control unit 11 reads programs and data stored in the storage unit 12 or ROM (Read Only Memory) using a built-in clock, counter, etc., and executes them to perform various control processes and calculation processes.

[0034] The storage unit 12 includes a non-volatile memory element, such as a flash memory or an EEPROM (Electrically ErasableProgrammable Read Only Memory). The storage unit 12 stores various programs and data referenced by the control unit 11. In the present embodiment, the storage unit 12 stores a program 121 for causing a computer to execute processing related to grip detection (grip judgment) and fault state judgment (fault judgment). The storage unit 12 also stores predetermined values ​​and specified values ​​for fault judgment, as well as threshold values ​​related to grip judgment. The predetermined values, specified values, and threshold values ​​will be described later.

[0035] The program (program product) stored in the storage unit 12 may be recorded on a recording medium in a computer-readable form. The storage unit 12 stores the program read from the recording medium 1A by a reading device (not shown). The recording medium 1A is, for example, a magnetic disk, an optical disk, a semiconductor memory, etc. In addition, the program may be downloaded from an external server connected to a communication network (not shown) and stored in the storage unit 12. The program 121 may be a single computer program or may be composed of a plurality of computer programs, and may be executed on a single computer or on a plurality of computers interconnected by a network.

[0036] The capacitance measurement circuit 13 is connected to the sensor electrode 21 and the shielding electrode 22 of the steering wheel 2, and is a circuit for measuring the electrostatic capacitance of the sensor electrode 21. The control unit 11 obtains the electrostatic capacitance value measured by the capacitance measurement circuit 13, and performs holding detection based on the obtained electrostatic capacitance value. Specifically, the control unit 11 compares the above-mentioned electrostatic capacitance value with a predetermined threshold value to determine whether the steering wheel 2 is in a holding state or a non-holding state, that is, to perform a holding judgment. Here, the holding state refers to the state in which the driver holds the steering wheel 2, and the non-holding state refers to the state in which the driver does not hold the steering wheel 2 and lets go.

[0037] The communication unit 14 is a communication interface for sending and receiving data with other vehicle-mounted devices via the in-vehicle network. The communication unit 14 is connected to a communication line (LAN) provided in the vehicle, and transmits and receives information with the driving assistance ECU 6, etc. The communication unit 14 transmits the judgment result of the control unit 11 to the driving assistance ECU 6.

[0038] The driving assistance ECU 6 is an ECU that performs processing related to the advanced driving assistance system. The driving assistance ECU 6 receives a signal indicating the grip judgment result from the control unit 11 via the communication unit 14, and performs predetermined processing related to the advanced driving assistance system according to the grip judgment result. For example, during automatic driving, if a grip judgment result indicating that the steering wheel 2 is in a non-gripped state is received from the control unit 11, the driving assistance ECU 6 ends the automatic driving. The processing of the driving assistance ECU 6 is not limited to automatic driving, and can also be, for example, lane keeping assistance, parking assistance, etc.

[0039] Figure 41 is an explanatory diagram showing a specific connection example of the capacitance measurement circuit 13, etc. The capacitance measurement circuit 13 includes a connector 130, an electrostatic capacitance sensor 131, an additional circuit 132, a first switch 13a, and a second switch 13b. The connector 130 includes a sensor connector 130a connected to the sensor electrode 21 and a shield connector 130b connected to the shield electrode 22. The electrostatic capacitance sensor 131 includes a resistor Ra connected to the sensor connector 130a, a resistor Rb connected to the shield connector 130b, an ammeter A connected to the resistor Ra, an AC power supply Sa connected to the ammeter A, and an AC power supply Sb connected to the resistor Rb. The AC power supply Sa and the AC power supply Sb apply the same voltage to the sensor electrode 21 and the shield electrode 22. The ammeter A measures the amount of current flowing from the AC power supply Sa to the sensor electrode 21, and the electrostatic capacitance sensor 131 obtains the electrostatic capacitance value of the sensor electrode 21 based on the amount of current measured by the ammeter A. In addition, the larger the amount of current measured by the ammeter A, the larger the electrostatic capacitance value obtained by the electrostatic capacitance sensor 131.

[0040] The shielding electrode 22 is connected to the core rod 23 having the same potential (GND potential) as the ground (GND) via the first switch 13a. When the first switch 13a is turned on, the shielding electrode 22 and the core rod 23 can be energized in a short-circuited state. In addition, the shielding electrode 22 is connected to the additional circuit 132 via the second switch 13b. When the second switch 13b is turned on, the shielding electrode 22 and the additional circuit 132 can be energized.

[0041] The additional circuit 132 includes a voltage applying circuit 132 a , a resistor Rc, and a voltmeter V. When the second switch 13 b is turned on, the voltage applying circuit 132 a applies a voltage to the shield electrode 22 . The voltmeter V acquires the value of the voltage applied to the shield electrode 22 by the voltage applying circuit 132 a .

[0042] The control unit 11 can obtain the capacitance value from the capacitance sensor 131 and the voltage value from the voltmeter V. In addition, the first switch 13a and the second switch 13b are switched on or off under the control of the control unit 11. The control unit 11 only turns on one of the first switch 13a or the second switch 13b, and does not turn on both switches at the same time. In addition, the control unit 11 can control the voltage application circuit 132a to apply a voltage to the shielding electrode 22.

[0043] An insulator In is provided between the sensor electrode 21 and the shield electrode 22, thereby forming a capacitor Cs. In a state where no fault occurs (normal state), the same voltage is applied to the sensor electrode 21 and the shield electrode 22, so that no current can be passed between the sensor electrode 21 and the shield electrode 22 (capacitor Cs). However, in a state where a fault occurs (fault state), when a potential difference is generated between the sensor electrode 21 and the shield electrode 22, the capacitor Cs can be energized.

[0044] Figure 4 The dotted line shown represents the circuit when the driver holds the steering wheel 2. When the driver holds the steering wheel 2, the sensor electrode 21 is electrically connected to the chassis 7 through the driver's body and the vehicle seat or the air inside the vehicle. The chassis 7 is connected to GND and has a potential of GND. The driver's body forms a capacitor Cb with resistance, so even in the holding state, if there is another circuit with a lower resistance value connected from the sensor electrode 21 to GND, the capacitor Cb will not be energized.

[0045] Figure 5 It is a table showing the electrostatic capacitance value acquired by the electrostatic capacitance sensor 131 in each fault mode when the first switch 13a is opened. In the present embodiment, the fault state includes five fault modes. The sensor open mode is a state in which the sensor electrode 21 and the sensor connector 130a are disconnected and cannot be energized. The shield open mode is a state in which the shield electrode 22 and the shield connector 130b are disconnected and cannot be energized. The sensor ground short-circuit mode is a state in which the sensor electrode 21 is short-circuited with the core rod 23 as the GND potential. The shield ground short-circuit mode is a state in which the shield electrode 22 is short-circuited with the core rod 23 as the GND potential. The sensor shield short-circuit mode is a state in which the sensor electrode 21 and the shield electrode 22 are short-circuited.

[0046] When no fault occurs and the device is in the non-holding state, when the first switch 13a is turned on to short-circuit the shielding electrode 22 and the core rod 23, the potential of the shielding electrode 22 becomes the GND potential, and a potential difference is generated between the sensor electrode 21 and the shielding electrode 22. As a result, the capacitor Cs can be energized, and current flows through the ammeter A. In addition, when no fault occurs and the device is in the holding state, since the capacitor Cb can be energized, current flows through the ammeter A. Therefore, when no fault occurs, the electrostatic capacitance value is large regardless of the holding state or the non-holding state.

[0047] When the sensor is in the non-holding state in the sensor-on mode, since the sensor electrode 21 and the sensor connector 130a are disconnected, the current does not flow through the ammeter A. In addition, when the sensor is in the holding state in the sensor-on mode, the current also does not flow through the ammeter A. Therefore, in the sensor-on mode, the electrostatic capacitance value is small regardless of the holding state or the non-holding state.

[0048] When the shield open mode is in the non-holding state, if the first switch 13a is turned on and the shield electrode 22 and the core rod 23 are in the short-circuited state, the shield electrode 22 becomes the GND potential, but since the electrostatic capacitance between the sensor electrode 21 and GND is smaller than the electrostatic capacitance between the sensor electrode 21 and the shield electrode 22, the current does not flow through the ammeter A. In addition, when the shield open mode is in the holding state, the capacitor Cb can be energized, so the current flows through the ammeter A. Therefore, in the shield open mode, when in the non-holding state, the electrostatic capacitance value is small, and when in the holding state, the electrostatic capacitance value is large.

[0049] In the sensor ground short-circuit mode, if the first switch 13a is turned on and the shielding electrode 22 and the core rod 23 are in a short-circuit state, the sensor electrode 21 becomes the GND potential, so the potential difference between the two ends of the AC power supply Sa becomes smaller. Therefore, no current flows through the ammeter A in either the gripping state or the non-gripping state, and the electrostatic capacitance value is small in either the gripping state or the non-gripping state.

[0050] In the shield ground short-circuit mode, when the first switch 13a is opened, the connection state becomes the same as when the first switch 13a is opened to short-circuit the shield electrode 22 and the core rod 23 in a state without a fault. Therefore, the electrostatic capacitance value is large regardless of the gripping state or the non-gripping state.

[0051] In the sensor shield short-circuit mode, if the first switch 13a is turned on and the shield electrode 22 and the core rod 23 are in a short-circuit state, the sensor electrode 21 becomes the GND potential, so the potential difference between the two ends of the AC power supply Sa becomes smaller. Therefore, no current will flow through the ammeter A in either the gripping state or the non-gripping state, and the electrostatic capacitance value is small in either the gripping state or the non-gripping state.

[0052] When the electrostatic capacitance value obtained from the electrostatic capacitance sensor 131 is less than the threshold value, the control unit 11 determines that the electrostatic capacitance value is small, and when the electrostatic capacitance value is greater than the threshold value, the control unit 11 determines that the electrostatic capacitance value is large. Figure 5As shown, the case where the electrostatic capacitance value is small is a certain fault mode, so the control unit 11 can judge the case where the electrostatic capacitance value is small as a fault state. In addition, in the shield open mode, the electrostatic capacitance value is large when in the grip state, and the electrostatic capacitance value is small when in the non-grip state. Therefore, the control unit 11 can judge the fault based on the shield open mode in the non-grip state. If the fault judgment is performed when the driver does not grip the steering wheel 2, the fault based on the shield card open mode can be judged, so there will be no problem with the fault judgment based on the shield open mode.

[0053] In addition, when the second switch 13b is turned on, the control unit 11 determines whether it is the shielding ground short-circuit mode. Specifically, the control unit 11 causes the voltage application circuit 132a to apply a voltage to the shielding electrode 22 when the second switch 13b is turned on and the first switch 13a is turned off. The control unit 11 obtains the voltage value of the voltage applied to the shielding electrode 22 from the voltmeter V. When the shielding electrode 22 is short-circuited with the core rod 23, the potential difference between the two ends of the additional circuit 132 becomes smaller, and the voltage value measured by the voltmeter V also becomes smaller. When the voltage value is less than the specified value, the control unit 11 determines that it is a fault state based on the shielding ground short-circuit mode.

[0054] When the second switch 13b is opened, the control unit 11 determines whether the fault state is based on the shielding ground short-circuit mode based on the voltage value obtained from the voltmeter V. If it is not a fault state based on the shielding ground short-circuit mode, the first switch 13a is opened to determine whether the fault state is based on a fault mode other than the shielding ground short-circuit mode. In this way, the control unit 11 can judge the fault state based on all fault modes without omission.

[0055] Figure 6 1 is a flowchart showing an example of the processing procedure of the control unit 11. The control unit 11 may execute the processing in the following flowcharts according to the program 121 stored in the storage unit 12 of the grip detection ECU 1, or may be implemented by a dedicated hardware circuit such as FPGA or ASIC provided in the control unit 11, or may be implemented by a combination thereof. For example, after detecting the activation of the sensor electrode 21, the control unit 11 of the grip detection ECU 1 repeatedly executes the following processing at a predetermined or appropriate time interval.

[0056] The control unit 11 opens the second switch 13b (S1) and causes the voltage application circuit 132a to apply a voltage to the shield electrode 22 (S2). The control unit 11 obtains the voltage value applied by the voltage application circuit 132a to the shield electrode 22 from the voltmeter V (S3). The control unit 11 determines whether the obtained voltage value is greater than a specified value (S4). If the voltage value is less than the specified value (S4: No), it is determined that the shield electrode 22 and the core rod 23 are in a fault state of short circuit (S5), and the determination result is transmitted to, for example, the driving assistance ECU 6 (S6), and the processing ends.

[0057] If the voltage value is greater than the specified value (S4: Yes), the control unit 11 opens the first switch 13a (S7) and obtains the electrostatic capacitance value (first electrostatic capacitance value) in the state where the shielding electrode 22 and the core rod 23 are short-circuited from the electrostatic capacitance sensor 131 (S8). In addition, the control unit 11 opens the second switch 13b (S9) and obtains the second electrostatic capacitance value from the electrostatic capacitance sensor 131 (S10). The control unit 11 determines whether the first electrostatic capacitance value is greater than the predetermined value (S11). When the first electrostatic capacitance value is less than the predetermined value (S11: No), the control unit 11 determines that it is a fault state (S12), transmits the judgment result to, for example, the driving assistance ECU 6 (S13), and ends the processing.

[0058] When the first electrostatic capacitance value is greater than a predetermined value (S11: Yes), the control unit 11 determines whether the second electrostatic capacitance value is greater than a threshold value related to the grip judgment (S14). When the second electrostatic capacitance value is greater than the threshold value (S14: Yes), the control unit 11 determines that the steering wheel 2 is in a gripped state (S15). When the second electrostatic capacitance value is less than the threshold value (S14: No), the control unit 11 determines that the steering wheel 2 is in a non-gripped state (S16). The control unit 11 transmits the judgment result in S15 or S16 to, for example, the driving assistance ECU 6 (S17), and returns the processing to S2.

[0059] According to the above structure and processing, whether the steering wheel 2 is faulty can be determined in any case, regardless of whether the steering wheel is held by the driver or not. In addition, since the fault is determined based on the electrostatic capacitance value at the measurement time node, it is not necessary to obtain the amplitude of the change in the electrostatic capacitance value over time, so the fault can be determined in a short time. In addition, by switching the first switch 13a and the second switch 13b, a single circuit structure can be used for holding judgment and fault judgment, so there is no need to set up another circuit or system for fault judgment, thereby reducing the cost of producing the holding detection device. In addition, since the holding judgment and fault judgment are repeated, the misjudgment of the holding judgment caused by a fault can be prevented.

[0060] In addition, when symbols are described in the claims, the symbols are symbols added as references corresponding to the symbols described in the embodiments to facilitate understanding of the claims, and do not limit the claims.

[0061] The embodiments disclosed this time are illustrative and non-restrictive in all aspects. The technical features described in the embodiments can be combined with each other, and the scope of the present invention is intended to include all changes in the claims and the scope equivalent to the claims. In addition, the independent claims and dependent claims recorded in the claims can be combined with each other in all combinations regardless of the form of reference. Moreover, the recording format of claims that refer to two or more other claims, that is, the multiple claim format, is used in the claims, but the present invention is not limited to this format. It is also possible to record using the recording format of multiple claims (multiple-multiple claims) that refer to at least one multiple claim.

[0062] Explanation of symbols

[0063] 1 Grip detection ECU (grip detection device)

[0064] 11. Control Unit

[0065] 13 Capacitance Measurement Circuit

[0066] 13a First switch

[0067] 13b Second switch

[0068] 131 Capacitance Sensor

[0069] 132 Additional Circuits

[0070] 2 Steering wheel

[0071] 21 Sensor electrodes

[0072] 22 Shielding electrode

[0073] 23 Mandrel

[0074] Insulator

Claims

1. A grip detection device (1), which is a grip detection device (1) for a steering wheel (2), the steering wheel (2) comprising a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) through an insulator (In), and a sensor electrode (21) arranged on the outside of the shielding electrode (22) through an insulator (In), wherein: The invention comprises a control unit (11), wherein the control unit (11) obtains the electrostatic capacitance value of the sensor electrode (21) when the shielding electrode (22) and the core rod (23) are short-circuited, and determines whether there is a fault based on the electrostatic capacitance value.

2. The grip detection device (1) according to claim 1, wherein: The invention comprises a first switch (13a), wherein the first switch (13a) is arranged between the shielding electrode (22) and the core rod (23), and the shielding electrode (22) and the core rod (23) are put into a short-circuit state by opening the switch. The control unit (11) determines whether there is a fault when the first switch (13a) is in an open state.

3. The grip detection device (1) according to claim 1 or 2, wherein: When the acquired electrostatic capacity value is smaller than a predetermined value, the control unit (11) determines that it is a fault state.

4. The grip detection device (1) according to claim 1 or 2, wherein: comprising an additional circuit (132) connected to the shielding electrode (22), applying a voltage to the shielding electrode (22), and measuring a voltage value of the applied voltage, When the voltage value of the voltage applied by the additional circuit (132) is lower than a specified value, the control unit (11) determines that it is a fault state in which the shield electrode (22) and the core rod (23) are short-circuited.

5. The grip detection device (1) according to claim 4, wherein: The invention comprises a second switch (13b), wherein the second switch (13b) is arranged between the shielding electrode (22) and the additional circuit (132), and the shielding electrode (22) and the additional circuit (132) can be energized by turning on the switch. The control unit (11) determines whether the shielding electrode (22) and the core rod (23) are in a short-circuit state when the second switch (13b) is turned on.

6. The grip detection device (1) according to claim 5, wherein: The control unit (11) determines whether the steering wheel (2) is being held when the second switch (13b) is turned on.

7. A fault judgment method, which is a fault judgment method for a grip detection device (1) of a steering wheel (2), wherein the steering wheel (2) comprises a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) through an insulator (In), and a sensor electrode (21) arranged on the further outside of the shielding electrode (22) through an insulator (In), wherein: When the shielding electrode (22) and the core rod (23) are short-circuited, the electrostatic capacitance value of the sensor electrode (21) is obtained, and the presence or absence of a fault is determined based on the electrostatic capacitance value.

8. A program executed by a computer, which is a program for performing fault judgment on a grip detection device (1) of a steering wheel (2), the steering wheel (2) comprising a core rod (23), a shielding electrode (22) arranged on the outside of the core rod (23) through an insulator (In), and a sensor electrode (21) arranged on the outside of the shielding electrode (22) through an insulator (In), wherein: When the shielding electrode (22) and the core rod (23) are short-circuited, the electrostatic capacitance value of the sensor electrode (21) is obtained, and the presence or absence of a fault is determined based on the electrostatic capacitance value.

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