Steering device and safe driving support system

Abstract

To provide a steering device and a safe driving support system which can determine whether a driver is gripping a steering handle or not with high accuracy, while distinguishing contact of a foreign matter with the steering handle from contact of the hand of the driver with the handle.SOLUTION: A steering device comprises: a steering handle; a torque sensor that detects steering torque; a measurement circuit that measures electrostatic capacitance of an electrode part provided in the steering handle; and a griping determination part that determines whether a rim part of the steering handle is griped or not. After determining that the steering handle is gripped on the basis of a measured result of the electrostatic capacitance by the measurement circuit, the gripping determination device determines that a foreign matter is in contact with the rim part and the rim part is not gripped, when a state where an absolute value of a detected value Tr_d of the steering torque is less than a predetermined torque threshold Tr_th continues for more than a predetermined time threshold T_th.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a steering device and a safe driving support system, and more particularly to a steering device and a safe driving support system that accepts a steering operation by a driver. [Background technology]

[0002] In recent years, efforts to provide access to sustainable transportation systems that take into consideration vulnerable transport participants have been gaining momentum. To achieve this, we are focusing on research and development into driving assistance functions such as lane keeping, lane departure prevention, and leading vehicle following functions to further improve road safety and convenience.

[0003] In a vehicle equipped with such a driving assistance function, a sensor device such as that shown in Patent Document 1 may be used to determine whether the driver is holding the steering wheel, and if it is determined that the driver is not holding the steering wheel, the device may prompt the driver to hold the steering wheel or cancel any driving assistance function that is being executed.

[0004] The sensor device disclosed in Patent Document 1 determines whether or not the driver is gripping the steering wheel based on the measured value of the electrostatic capacitance of electrodes provided on the steering wheel. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2016-203660 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when determining whether or not the driver is gripping the steering wheel based on capacitance measurements, as in the sensor device described in Patent Document 1, if a foreign object having capacitance (e.g., a wet towel, a mobile information terminal, a beverage container, etc.) is in contact with the steering wheel, there is a risk that the device will erroneously determine that the driver is gripping the steering wheel when in fact he or she is not.

[0007] Therefore, in the sensor device described in Patent Document 1, if the measured capacitance value is equal to or greater than a predetermined value and the driver's heartbeat is not detected, it is determined that a foreign object is in contact with the steering wheel. However, in this case, it is necessary to provide a heartbeat detection device that detects the heartbeat of the driver gripping the steering wheel, which may increase costs.

[0008] The present invention aims to provide a steering device and a safe driving support system that can accurately determine whether or not the driver is gripping the steering wheel while distinguishing between contact of a foreign object with the steering wheel and contact of the driver's hands with the steering wheel, and ultimately aims to contribute to the development of a sustainable transportation system. [Means for solving the problem]

[0009] (1) A steering device according to the present invention (for example, a steering device 1 described later) includes a steering wheel (for example, a steering wheel 2 described later) that receives a steering operation of a vehicle by a driver, a torque sensor (for example, a torque sensor 31 described later) that detects a steering torque acting on the steering wheel, a measuring device (for example, measuring circuits 62R, 62L, 62U, 62D described later) that measures the electrostatic capacitance of an electrode portion (for example, electrode portions 60R, 60L, 60U, 60D described later) provided on the steering wheel, and a measuring circuit (for example, measuring circuits 62R, 62L, 62U, 62D described later) that measures the electrostatic capacitance of the electrode portion (for example, electrode portions 60R, 60L, 60U, 60D described later). and a gripping determination device (e.g., gripping determination device 60 described later) that determines whether or not the steering handle is being gripped, wherein the gripping determination device determines that the steering handle is not being gripped if the absolute value of the torque detection value (e.g., detection value Tr_d described later) by the torque sensor remains below a predetermined torque threshold value (e.g., torque threshold value Tr_th described later) for a period exceeding a predetermined time threshold value (e.g., time threshold value T_th described later).

[0010] (2) In this case, it is preferable that the grip determination device obtains the grip position of the steering handle based on the measurement result, and changes either or both of the torque threshold value and the time threshold value based on the grip position.

[0011] (3) The safety driving support system according to the present invention is characterized in that it includes the steering device and a control device group (e.g., the control device group 8 described below) communicatively connected to the gripping determination device.

[0012] (4) In this case, it is preferable that the control device group includes a notification device (for example, notification device 81 described later) that notifies the driver of information generated based on the determination result by the grip determination device.

[0013] (5) In this case, it is preferable that the alarm device changes the alarm mode depending on whether it is determined that the steering wheel is not being gripped based on the measurement results or whether it is determined that the steering wheel is not being gripped in response to the state in which the absolute value of the torque detection value is less than the torque threshold value continuing beyond the time threshold value.

[0014] (6) In this case, it is preferable that the control device group includes a safe driving skill evaluation device (for example, safe driving skill evaluation device 82 described below) that evaluates the safe driving skill of the driver based on the judgment result by the grip judgment device.

[0015] (7) In this case, it is preferable that the control device group includes an autonomous driving device (e.g., autonomous driving device 83 described below) that executes autonomous driving control according to multiple autonomous driving levels, and that the autonomous driving device changes the autonomous driving level based on the judgment result by the gripping judgment device. Effect of the Invention

[0016] (1) When a driver grips a steering wheel, a slight but intermittent steering torque is generated not only when turning right or left, but also when driving straight. Therefore, the grip determination device determines that the steering wheel is gripped based on the measurement result of the capacitance of the electrode part provided on the steering wheel, and then determines that a foreign object having capacitance is in contact with the steering wheel and that the steering wheel is not gripped if the absolute value of the torque detection value by the torque sensor is less than the torque threshold value and continues to be less than the time threshold value, that is, if no significant steering torque is detected for the time threshold value. Therefore, according to the present invention, it is possible to accurately determine whether or not the driver is gripping the steering wheel while distinguishing between contact of a foreign object with the steering wheel and contact of the driver's hand, and thus to contribute to the development of a sustainable transportation system. In addition, since the present invention does not need to detect the driver's heart rate as described above, costs can be reduced compared to the conventional art.

[0017] (2) The magnitude of the steering torque generated when a driver drives while gripping a steering wheel varies depending on the gripping position of the steering wheel. Therefore, according to the present invention, by changing either or both of the torque threshold value and the time threshold value based on the gripping position of the steering wheel, it is possible to accurately distinguish between contact of a foreign object with the steering wheel and contact of the driver's hand with the steering wheel.

[0018] (3) A safe driving support system includes a steering device and a control device group communicably connected to a grip determination device of the steering device. The control device group can support safe driving by a driver based on the result of the grip determination device's determination of whether the steering wheel is being gripped and the result of the determination of whether a foreign object is in contact with the steering wheel, thereby contributing to the development of a sustainable transportation system.

[0019] (4) The notification device notifies the driver of information generated based on the result of the determination by the grip determination device. As a result, for example, when the driver is not gripping the steering wheel or when a foreign object is touching the steering wheel, the notification device can prompt the driver to grip the steering wheel properly or remove the foreign object, thereby supporting the driver in driving safely.

[0020] (5) The alarm device changes the alarm mode depending on whether it is determined that the steering wheel is not being held based on the capacitance measurement results or whether it is determined that the steering wheel is not being held because the absolute value of the torque detection value remains below the torque threshold for a period exceeding a time threshold.This allows the driver to be urged to hold the steering wheel properly or to remove any foreign object that is estimated to be in contact with the steering wheel, thereby assisting the driver in safe driving.

[0021] (6) The safe driving skill assessment device evaluates the driver's driving skill based on the judgment result by the grip judgment device. This makes it possible to distinguish between a case where the driver is not gripping the steering wheel properly and a case where a foreign object is touching the steering wheel and evaluate the driving skill, thereby supporting the driver's safe driving.

[0022] (7) The autonomous driving device changes the autonomous driving level based on the result of the judgment by the grip judgment device. This allows the autonomous driving level to be changed by distinguishing between a case where the driver is not gripping the steering wheel and a case where a foreign object is touching the steering wheel, thereby supporting the driver in driving safely. [Brief description of the drawings]

[0023] [Figure 1] 1 is a diagram showing the configuration of a steering device according to an embodiment of the present invention and a safe driving support system including the steering device; [Diagram 2] FIG. 4 is a diagram showing a circuit configuration of a grip sensor unit. [Diagram 3] 13 is a flowchart showing a specific procedure of a gripping determination process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steering device and a safe driving support system according to an embodiment of the present invention will be described below with reference to the drawings.

[0025] FIG. 1 is a diagram showing the configuration of a steering device 1 according to this embodiment and a safe driving support system 9 including this steering device 1.

[0026] The safe driving support system 9 includes a steering device 1 mounted on a vehicle (not shown) and a control device group 8 communicatively connected to the steering device 1, and supports the driver in safe driving of the vehicle by using the steering device 1 and the control device group 8.

[0027] In this embodiment, the devices 81 to 83 constituting the control device group 8 are described as in-vehicle devices capable of communicating with the steering device 1 by, for example, CAN communication via the CAN bus 80, but the present invention is not limited to this. All or some of the multiple devices 81 to 83 constituting the control device group 8 may be external devices capable of wirelessly communicating with the steering device 1 via an in-vehicle communication device (not shown).

[0028] The steering device 1 includes a steering handle 2 that receives vehicle steering operations and auxiliary operation of vehicle accessories by the driver, a steering shaft 3 that supports the steering handle 2, and a grip sensor unit 6 that determines whether or not the driver is gripping the steering handle 2 and further acquires the grip position.

[0029] The steering handle 2 comprises a circular rim portion 20 that 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 extending radially from the hub portion 23 and connected to the inner peripheral portion of the rim portion 20.

[0030] 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 a part of the vehicle body (not shown). Therefore, the steering torque generated by the driver turning the steering wheel 2 is transmitted to the steering mechanism (not shown) by the steering shaft 3. In addition, the steering shaft 3 is provided with a torque sensor 31 that detects the steering torque acting on the steering shaft 3 and outputs a signal corresponding to the detected value to the grip sensor unit 6.

[0031] 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 inner circumference of the rim portion 20 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 inner circumference of the rim portion 20 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 inner circumference of the rim portion 20 as seen by the driver.

[0032] As described above, the rim portion 20 has a circular shape when seen by the driver, and the driver can grip the entire circumference of the rim portion 20. In addition, the rim portion 20 is provided with a plurality of electrodes 60R, 60L, 60U, and 60D of the grip sensor unit 6, which will be described later, over the entire circumference.

[0033] 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.

[0034] In the following description, the positions of the rim portion 20 and the steering shaft 3, which are substantially circular as viewed from 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 21 of the rim portion 20 as viewed from the driver as the reference. That is, the right spoke portion 25R extends along a 90° direction and connects the 90° portion of the hub portion 23 and the rim portion 20. The lower spoke portion 25D extends along a 180° direction and connects the 180° portion of the hub portion 23 and the 180° portion of the rim portion 20, i.e., the lower end portion 22 of the rim portion 20 as viewed from the driver. The left spoke portion 25L extends along a 270° direction and connects the 270° portion of the hub portion 23 and the rim portion 20.

[0035] FIG. 2 is a diagram showing a circuit configuration of the grip sensor unit 6. As shown in FIG. The grip sensor unit 6 comprises multiple (four in this embodiment) proximity sensors 6R, 6L, 6U, 6D, each with a different detection target area, and a grip determination device 60 that determines whether or not the driver is gripping the steering wheel 2 based on the measurement results of these proximity sensors 6R, 6L, 6U, 6D, and further acquires the grip position.

[0036] The right proximity sensor 6R includes a right electrode portion 60R provided on the rim portion 20 and a right measurement circuit 62R electrically connected to the right electrode portion 60R. The right electrode portion 60R is arc-shaped extending along the rim portion 20 and is conductive. The right electrode portion 60R is provided inside the rim portion 20. The right electrode portion 60R is disposed in a range of about 90° between 45° and 135° of the rim portion 20 (i.e., a range that the driver can hold with his right hand mainly when driving straight). In the following, the area of ​​the rim portion 20 where the right electrode portion 60R is disposed is also referred to as the right grip portion 20R. The right measurement circuit 62R is connected to the right electrode portion 60R via a wiring 61R. The right measurement circuit 62R measures the electrostatic capacitance between the right electrode portion 60R and the ground as a value that increases or decreases depending on the distance between the position where the right electrode portion 60R is disposed and the human body. The closer the position of the right electrode unit 60R is to the human body, the greater the capacitance between the right electrode unit 60R and ground. The capacitance measurement value Ch_R by the right measurement circuit 62R is transmitted to the grip determination device 60.

[0037] The right measurement circuit 62R includes a pulse power supply 63, an amplifier 64, a first switch 65, a second switch 66, a charging capacitor 67, and a capacitance measurement unit 68. In Fig. 2, the capacitance between the right electrode unit 60R and the ground (for example, the vehicle body) is illustrated as being divided into a capacitance Ch formed by the 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 excluding the human body H.

[0038] As shown in FIG. 2, the pulse power supply 63 and the amplifier 64 are connected in series. The second switch 66 and the charging capacitor 67 are connected in parallel. The series circuit consisting of the pulse power supply 63 and the amplifier 64 and the parallel circuit consisting of the second switch 66 and the charging capacitor 67 are connected via the first switch 65. The output terminal of the amplifier 64 and the first switch 65 are connected to the right electrode section 60R via the wiring 61R. Therefore, the pulse power supply 63 is connected to the right electrode section 60R via the amplifier 64 and the wiring 61R. In addition, the second switch 66 and the charging capacitor 67 are connected to the right electrode section 60R via the first switch 65 and the wiring 61R, respectively.

[0039] In response to a command from the grip determination device 60, the pulse power supply 63 supplies a pulse voltage Vs of a predetermined frequency and a predetermined voltage to the amplifier 64. The amplifier 64 amplifies the pulse voltage Vs supplied from the pulse power supply 63 and applies it to the right electrode portion 60R.

[0040] The second switch 66 is a switching element that is turned on / off by a drive circuit (not shown). The drive circuit for the second switch 66 turns off the second switch 66 until the voltage VCref of the charging capacitor 67 reaches a predetermined threshold Vthr, for example, and turns on the second switch 66 after the voltage VCref reaches the threshold Vthr, thereby discharging the charge stored in the charging capacitor 67.

[0041] The first switch 65 is a switching element that is turned on / off by a drive circuit (not shown). The drive circuit for the first switch 65 turns off the first switch 65 in response to the rise of the pulse voltage Vs of the pulse power supply 63. As a result, the pulse voltage supplied from the pulse power supply 63 and the amplifier 64 is applied to the right electrode portion 60R, 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.

[0042] Furthermore, the drive circuit of the first switch 65 turns on the first switch 65 in response to the falling edge of the pulse voltage Vs of the pulse power supply 63. This connects the human body H and the floating capacitor E to the charging capacitor 67, and charge moves from the human body H and the floating capacitor E to the charging capacitor 67 via the path indicated by the arrow 2b in Fig. 2, charging the charging capacitor 67. This causes the voltage VCref of the charging capacitor 67 to rise.

[0043] Therefore, when a pulse voltage is applied to the right electrode section 60R by the pulse power supply 63 and the amplifier 64, charging and discharging of the human body H and the floating capacitor E are repeated alternately, and the voltage VCref of the charging capacitor 67 gradually increases. At this time, the time until the voltage VCref of the charging capacitor 67 reaches the threshold value Vthr (or the number of pulses of the pulse power supply 63) varies depending on the capacitance Ch formed by the human body H, that is, the distance between the right electrode section 60R and the driver's body. That is, when a part of the driver's body is in contact with or close to the position of the right electrode section 60R of the rim section 20 and the capacitance Ch is high, the time until the voltage VCref of the charging capacitor 67 reaches the threshold value Vthr is short, and when a part of the driver's body is away from the position of the right electrode section 60R and the capacitance Ch is low, the time until the voltage VCref of the charging capacitor 67 reaches the threshold value Vthr is long.

[0044] The capacitance measuring unit 68 measures the time and the number of pulses until the voltage VCref of the charging capacitor 67 reaches the threshold value Vthr, and indirectly measures the capacitance Ch formed by the human body H present in the vicinity of the right electrode unit 60R based on this measurement result. The capacitance measuring unit 68 transmits the measurement value Ch_R of the capacitance Ch obtained by the above procedure to the grip determination device 60.

[0045] The left proximity sensor 6L includes a left electrode portion 60L provided on the rim portion 20 and a left measurement circuit 62L electrically connected to the left electrode portion 60L. The left electrode portion 60L is arc-shaped extending along the rim portion 20 and is conductive. The left electrode portion 60L is provided inside the rim portion 20. The left electrode portion 60L is disposed in a range of about 90° between 225° and 315° of the rim portion 20 (i.e., a range that the driver can hold with his left hand mainly when driving straight). In the following, the area of ​​the rim portion 20 where the left electrode portion 60L is disposed is also referred to as the left grip portion 20L. The left measurement circuit 62L is connected to the left electrode portion 60L via a wiring 61L. The left measurement circuit 62L measures the electrostatic capacitance between the left electrode portion 60L and the ground as a value that increases or decreases depending on the distance between the position where the left electrode portion 60L is disposed and the human body. The closer the position of the left electrode unit 60L is to the human body, the larger the capacitance between the left electrode unit 60L and ground. The capacitance measurement value Ch_L by the left measurement circuit 62L is transmitted to the grip determination device 60. Note that the circuit configuration of the left measurement circuit 62L is almost the same as that of the right measurement circuit 62R shown in FIG. 2, so a detailed description will be omitted.

[0046] The upper proximity sensor 6U includes an upper electrode portion 60U provided on the rim portion 20 and an upper measurement circuit 62U electrically connected to the upper electrode portion 60U. The upper electrode portion 60U is arc-shaped extending along the rim portion 20 and is conductive. The upper electrode portion 60U is provided inside the rim portion 20. The upper electrode portion 60U is disposed in a range of approximately 90° between 315° and 405° (45°) of the rim portion 20 (i.e., a range that the driver can hold with his right or left hand mainly when turning). In the following, the area of ​​the rim portion 20 where the upper electrode portion 60U is disposed is also referred to as the upper grip portion 20U. The upper measurement circuit 62U is connected to the upper electrode portion 60U via a wiring 61U. The upper measurement circuit 62U measures the electrostatic capacitance between the upper electrode portion 60U and the ground as a value that increases or decreases depending on the distance between the position where the upper electrode portion 60U is disposed and the human body. The closer the position of the upper electrode unit 60U is to the human body, the larger the capacitance between the upper electrode unit 60U and the ground. The capacitance measurement value Ch_U by the upper measurement circuit 62U is transmitted to the grip determination device 60. Note that the circuit configuration of the upper measurement circuit 62U is almost the same as that of the right measurement circuit 62R shown in FIG. 2, so a detailed description will be omitted.

[0047] The lower proximity sensor 6D includes a lower electrode portion 60D provided on the rim portion 20 and a lower measurement circuit 62D electrically connected to the lower electrode portion 60D. The lower electrode portion 60D is arc-shaped extending along the rim portion 20 and is conductive. The lower electrode portion 60D is provided inside the rim portion 20. The lower electrode portion 60D is arranged in a range of about 90° between 135° and 225° of the rim portion 20 (i.e., a range that the driver can hold with his right or left hand mainly when turning and a range of the rim portion 20 that is closest to the driver's knee). In the following, the area of ​​the rim portion 20 where the lower electrode portion 60D is arranged is also referred to as the lower grip portion 20D. The lower measurement circuit 62D is connected to the lower electrode portion 60D via a wiring 61D. The lower measurement circuit 62D measures the electrostatic capacitance between the lower electrode portion 60D and the ground as a value that increases or decreases depending on the distance between the arrangement position of the lower electrode portion 60D and the human body. The closer the position of the lower electrode unit 60D is to the human body, the larger the capacitance between the lower electrode unit 60D and the ground. The capacitance measurement value Ch_D by the lower measurement circuit 62D is transmitted to the grip determination device 60. Note that the circuit configuration of the lower measurement circuit 62D is almost the same as that of the right measurement circuit 62R shown in FIG. 2, so a detailed description will be omitted.

[0048] As described above, the right electrode portion 60R of the right proximity sensor 6R is provided in a position closer to the right grip portion 20R than the other electrode portions 60L, 60U, 60D. For this reason, the right proximity sensor 6R has the right grip portion 20R of the rim portion 20 as its detection target area. Therefore, when the right grip portion 20R is being held by the driver, or when a foreign object having capacitance, such as a wet towel, a mobile information terminal, or a beverage container, is in contact with the right grip portion 20R, the measurement value Ch_R by the right proximity sensor 6R becomes greater than a predetermined right capacitance threshold Ch_R_th.

[0049] The left electrode portion 60L of the left proximity sensor 6L is provided in a position closer to the left grip portion 20L than the other electrode portions 60R, 60U, 60D. For this reason, the left proximity sensor 6L has the left grip portion 20L of the rim portion 20 as its detection target area. Therefore, when the left grip portion 20L is gripped by the driver, or when a foreign object having the above-mentioned capacitance is in contact with the left grip portion 20L, the measurement value Ch_L by the left proximity sensor 6L becomes larger than a predetermined left capacitance threshold Ch_L_th.

[0050] The upper electrode portion 60U of the upper proximity sensor 6U is provided at a position closer to the upper grip portion 20U than the other electrode portions 60R, 60L, 60D. For this reason, the upper proximity sensor 6U has the upper grip portion 20U of the rim portion 20 as its detection target area. Therefore, when the upper grip portion 20U is being held by the driver, or when a foreign object having the above-mentioned capacitance is in contact with the upper grip portion 20U, the measurement value Ch_U by the upper proximity sensor 6U becomes greater than a predetermined upper capacitance threshold Ch_U_th.

[0051] Furthermore, the lower electrode portion 60D of the lower proximity sensor 6D is provided at a position closer to the lower grip portion 20D than the other electrode portions 60R, 60L, 60D. For this reason, the lower proximity sensor 6D has the lower grip portion 20D of the rim portion 20 as its detection target area. Therefore, when the lower grip portion 20D is being held by the driver, or when a foreign object having the above-mentioned capacitance is in contact with the lower grip portion 20D, the measurement value Ch_D by the lower proximity sensor 6D becomes greater than a predetermined lower capacitance threshold Ch_D_th.

[0052] As described above, the measurement values ​​Ch_R, Ch_L, Ch_U, Ch_D of the proximity sensors 6R, 6L, 6U, 6D change not only due to the driver's grip of the rim portion 20 but also due to contact of a foreign object with the rim portion 20, and therefore it is not possible to accurately determine whether or not the rim portion 20 is being gripped by these measurement values ​​Ch_R, Ch_L, Ch_U, Ch_D alone. Therefore, the grip determination device 60 executes a grip determination process, which will be described below with reference to FIG. 3, based on the measurement values ​​Ch_R, Ch_L, Ch_U, Ch_D acquired by the grip sensor unit 6 and the detection value Tr_d of the steering torque acquired by the torque sensor 31, to determine whether or not the driver is gripping the rim portion 20 while distinguishing between contact of a foreign object with the rim portion 20 and contact of the driver's hand.

[0053] Fig. 3 is a flowchart showing a specific procedure of the grip determination process by the grip determination device 60. The process shown in Fig. 3 is repeatedly executed in the grip determination device 60 under a predetermined control period in response to the driver operating a start switch (not shown) to start the vehicle.

[0054] First, in step ST1, the gripping determination device 60 acquires the capacitance measurement values ​​Ch_R, Ch_L, Ch_U, and Ch_D from the proximity sensors 6R, 6L, 6U, and 6D, and then proceeds to step ST2.

[0055] In step ST2, the grip determination device 60 determines whether or not an object, including the driver's hand and a foreign object having capacitance as described above, is in contact with the rim portion 20 based on the measured values ​​Ch_R, Ch_L, Ch_U, and Ch_D acquired in step ST1. More specifically, the grip determination device 60 determines that an object is in contact with the rim portion 20 when at least one of the measured values ​​Ch_R, Ch_L, Ch_U, and Ch_D is greater than the capacitance threshold values ​​Ch_R_th, Ch_L_th, Ch_U_th, and Ch_D_th set for each of them. In addition, the grip determination device 60 determines that an object is not in contact with the rim portion 20 when the measured values ​​Ch_R, Ch_L, Ch_U, and Ch_D are all equal to or less than the capacitance threshold values ​​Ch_R_th, Ch_L_th, Ch_U_th, and Ch_D_th.

[0056] If the determination result of step ST2 is NO, the grip determination device 60 proceeds to step ST11. In step ST11, the grip determination device 60 determines that the rim portion 20 is not being gripped by the driver, and proceeds to step ST12.

[0057] When the determination result of step ST2 is YES, the grip determination device 60 proceeds to step ST3. In step ST3, the grip determination device 60 acquires the contact position of the object with the rim portion 20 based on the measurements Ch_R, Ch_L, Ch_U, and Ch_D acquired in step ST1, and proceeds to step ST4. More specifically, the grip determination device 60 determines that the contact position of the object is the right grip portion 20R when the measurement value Ch_R is greater than the right capacitance threshold value Ch_R_th, that the contact position of the object is the left grip portion 20L when the measurement value Ch_L is greater than the left capacitance threshold value Ch_L_th, that the contact position of the object is the upper grip portion 20U when the measurement value Ch_U is greater than the upper capacitance threshold value Ch_U_th, and that the contact position of the object is the lower grip portion 20L when the measurement value Ch_D is greater than the lower capacitance threshold value Ch_D_th.

[0058] In step ST4, the grip determination device 60 sets a torque threshold Tr_th and a time threshold T_th, which will be described later, based on the contact position acquired in step ST3, and proceeds to step ST5. More specifically, the grip determination device 60 determines the position farthest from the lower end 22 among the contact positions acquired in step ST3 as the uppermost contact position, and sets the torque threshold Tr_th and the time threshold T_th based on this uppermost contact position. The upper grip portion 20U is farther from the lower end 22 than the other grip portions 20R, 20L, and 20D. The right grip portion 20R and the left grip portion 20L are farther from the lower end 22 than the lower grip portion 20D. The distance between the right grip portion 20R and the lower end 22 is equal to the distance between the left grip portion 20L and the lower end 22.

[0059] In this embodiment, the gripping determination device 60 changes both the torque threshold value Tr_th and the time threshold value T_th based on the uppermost contact position, but the present invention is not limited to this. The gripping determination device 60 may change only the torque threshold value Tr_th or only the time threshold value T_th based on the uppermost contact position. Furthermore, the gripping determination device 60 may set both the torque threshold value Tr_th and the time threshold value T_th to fixed values.

[0060] More specifically, the grip determination device 60 reduces the torque threshold Tr_th as the uppermost contact position approaches the lower end 22 of the rim portion 20 (i.e., the torque threshold Tr_th approaches 0). That is, when the uppermost contact position is the lower grip portion 20D, the grip determination device 60 reduces the torque threshold Tr_th compared to when the uppermost contact position is the upper grip portion 20U, the right grip portion 20R, or the left grip portion 20L. Furthermore, when the uppermost contact position is the right grip portion 20R or the left grip portion 20L, the grip determination device 60 reduces the torque threshold Tr_th compared to when the uppermost contact position is the upper grip portion 20U.

[0061] The magnitude of steering torque generated when a driver drives while gripping the rim portion 20 tends to decrease as the driver's gripping position approaches the lower end 22 of the rim portion 20 as seen by the driver. Therefore, in this embodiment, by making the torque threshold value Tr_th smaller as the uppermost contact position approaches the lower end 22 of the rim portion 20, it may be possible to more accurately distinguish between contact of a foreign object with the rim portion 20 and contact of the driver's hand.

[0062] The gripping determination device 60 lengthens the time threshold T_th as the uppermost contact position approaches the lower end 22 of the rim portion 20. That is, when the uppermost contact position is the lower grip portion 20D, the gripping determination device 60 lengthens the time threshold T_th compared to when the uppermost contact position is the upper grip portion 20U, the right grip portion 20R, or the left grip portion 20L. Also, when the uppermost contact position is the right grip portion 20R or the left grip portion 20L, the gripping determination device 60 lengthens the time threshold T_th compared to when the uppermost contact position is the upper grip portion 20U.

[0063] The closer the gripping position by the driver is to the lower end 22 of the rim portion 20 as seen by the driver, the less likely it is that a steering torque will be generated. Therefore, in this embodiment, by making the time threshold value T_th longer the closer the uppermost contact position is to the lower end 22 of the rim portion 20, it may be possible to more accurately distinguish between contact of a foreign object with the rim portion 20 and contact of the driver's hand.

[0064] As described above, in this embodiment, the grip determination device 60 reduces the torque threshold value Tr_th and increases the time threshold value T_th as the uppermost contact position approaches the lower end 22 of the rim portion 20, but the present invention is not limited to this. The grip determination device 60 may increase the torque threshold value Tr_th and shorten the time threshold value T_th as the uppermost contact position approaches the lower end 22 of the rim portion 20. This may prevent erroneous determination that an object is being gripped when in fact it is not being gripped.

[0065] In step ST5, the grip determination device 60 determines whether the absolute value of the steering torque detection value Tr_d is equal to or greater than the torque threshold value Tr_th set in step ST4. If the determination result in step ST5 is NO, that is, if the absolute value of the steering torque detection value Tr_d is less than the torque threshold value Tr_th, the grip determination device 60 proceeds to step ST6.

[0066] In step ST6, the grip determination device 60 counts up a timer T for measuring the time during which the absolute value of the steering torque detection value Tr_d is less than the torque threshold value Tr_th by a control period ΔT (T←T+ΔT), and then proceeds to step ST7.

[0067] In step ST7, the gripping determination device 60 determines whether the timer T is equal to or greater than the time threshold T_th. If the determination result in step ST7 is NO, the gripping determination device 60 proceeds to step ST9, and if the determination result is YES, the gripping determination device 60 proceeds to step ST10.

[0068] If the determination result in step ST5 is YES, that is, if the absolute value of the detected steering torque value Tr_d is equal to or greater than the torque threshold value Tr_th, the gripping determination device 60 proceeds to step ST8. In step ST8, the gripping determination device 60 resets the timer T to an initial value (for example, 0), and proceeds to step ST9.

[0069] In step ST9, the grip determination device 60 determines that the rim portion 20 is gripped by the driver, and proceeds to step ST12. As described above, if the grip determination device 60 detects a steering torque exceeding the torque threshold value Tr_th after it has been determined that an object has contacted the rim portion 20 (see steps ST2 and ST5), it determines that the rim portion 20 is gripped at the contact position acquired in step ST3 as the grip position. Furthermore, if the time during which the absolute value of the steering torque detection value Tr_d is less than the torque threshold value Tr_th is less than the time threshold value T_th after it has been determined that an object has contacted the rim portion 20 (see steps ST2, ST5, and ST7), it determines that the rim portion 20 is provisionally gripped at the contact position acquired in step ST3 as the grip position.

[0070] In step ST10, the grip determination device 60 determines that a foreign object is in contact with the rim portion 20 at the contact position acquired in step ST3, and proceeds to step ST11. In addition, in step ST11, the grip determination device 60 determines that the rim portion 20 is not being gripped by the driver as described above, and proceeds to step ST12. As described above, after determining that the rim portion 20 is being gripped in response to determining that some object has come into contact with the rim portion 20 (see step ST9), if the state in which the absolute value of the steering torque detection value Tr_d is less than the torque threshold value Tr_th continues beyond the time threshold value T_th (see steps ST2, ST5, ST7, ST9), the grip determination device 60 determines that a foreign object is in contact with the rim portion 20 at the contact position acquired in step ST3 (see step ST10), and then determines that the rim portion 20 is not being gripped by the driver (see step ST11).

[0071] In step ST12, the gripping determination device 60 transmits information regarding the determination result as to whether or not the driver is gripping the rim portion 20, information regarding the gripping position, information regarding the determination result as to whether or not a foreign object has come into contact with the rim portion 20, and information regarding the contact position of the foreign object to the control device group 8, and then returns to step ST1.

[0072] Returning to FIG. 1, the control device group 8 includes a notification device 81, a safe driving skill evaluation device 82, and an automatic driving device 83.

[0073] The notification device 81 generates support information to support safe driving by the driver based on the information transmitted from the grip determination device 60, which is information on the result of the determination as to whether the rim portion 20 is being gripped, information on the grip position, information on the result of the determination as to whether the rim portion 20 is in contact with a foreign object, and information on the contact position of the foreign object, and notifies the driver of the generated support information via an HMI (Human Machine Interface) (not shown) provided in the vehicle. More specifically, when the grip determination device 60 determines that the driver is not gripping the rim portion 20 or when the driver is not gripping the rim portion 20 at the recommended grip position, the notification device 81 notifies the driver of support information urging the driver to grip the rim portion 20 at the recommended grip position through the driver's vision, hearing, touch, etc. by using the HMI. Furthermore, when it is determined that a foreign object is attached to the rim portion 20, the notification device 81 uses the HMI to notify the driver of support information urging the driver to grip the rim portion 20 at the recommended gripping position, as well as support information urging the driver to remove the foreign object attached to the rim portion 20. That is, it is preferable that the notification device 81 prompts the driver to remove the foreign object in contact with the rim portion 20 by changing the notification mode depending on whether it is determined that the rim portion 20 is not being gripped because the multiple measured values ​​Ch_R, Ch_L, Ch_U, and Ch_D are all less than the capacitance threshold value (when the judgment result in step ST2 is NO) or whether it is determined that the rim portion 20 is not being gripped because the absolute value of the detected steering torque value Tr_d is less than the torque threshold value Tr_th and continues to be less than the time threshold value T_th (when the judgment result in step ST7 is YES), i.e., when it is determined that a foreign object is in contact with the rim portion 20.

[0074] The safe driving skill evaluation device 82 evaluates the driver's safe driving skill based on information regarding the judgment result of whether or not the rim portion 20 is being gripped, information regarding the gripping position, information regarding the judgment result of whether or not a foreign object has come into contact with the rim portion 20, and information regarding the contact position of the foreign object, transmitted from the gripping judgment device 60.

[0075] The automatic driving device 83 executes automatic driving control according to a plurality of automatic driving levels. In this case, the automatic driving device 83 changes the automatic driving level based on information transmitted from the grip determination device 60 regarding the result of the determination as to whether the rim portion 20 is gripped or not and information regarding the result of the determination as to whether the rim portion 20 is in contact with a foreign object or not.

[0076] The steering device 1 and the safe driving support system 9 according to this embodiment provide the following advantages.

[0077] (1) When the driver grips the rim portion 20 of the steering wheel 2, a slight but intermittent steering torque is generated not only when turning right or left, but also when driving straight. Therefore, the grip determination device 60 determines that the rim portion 20 is being gripped based on the capacitance measurement values ​​Ch_R, Ch_L, Ch_U, and Ch_D of the multiple electrode portions 60Rm60L, 60U, and 60D provided on the steering wheel 2, and then determines that a foreign object having capacitance is in contact with the rim portion 20 of the steering wheel 2 and that the rim portion 20 is not being gripped if the absolute value of the steering torque detection value Tr_d by the torque sensor 31 is less than the torque threshold value Tr_th and continues to exceed the time threshold value T_th, that is, if no significant steering torque is detected over the time threshold value T_th. Therefore, according to the steering device 1, it is possible to accurately determine whether the driver is gripping the rim portion 20 while distinguishing between contact of a foreign object with the rim portion 20 and contact of the driver's hand, which can contribute to the development of a sustainable transportation system. Furthermore, with the steering device 1, there is no need to detect the driver's heart rate as described above, and therefore costs can be reduced compared to the conventional case.

[0078] (2) The magnitude of the steering torque generated when the driver drives while gripping the rim portion 20 varies depending on the gripping position of the rim portion 20. Therefore, according to the steering device 1, by changing either or both of the torque threshold value Tr_th and the time threshold value T_th based on the gripping position of the rim portion 20 of the steering wheel 2, it is possible to accurately distinguish between contact of a foreign object with the rim portion 20 and contact of the driver's hand with the rim portion 20.

[0079] (3) The safe driving support system 9 includes a steering device 1 and a control device group 8 communicatively connected to a grip determination device 60 of the steering device 1. As a result, the control device group 8 can support safe driving by the driver based on the result of the determination by the grip determination device 60 of whether the rim portion 20 is being gripped and the result of the determination of whether a foreign object has come into contact with the rim portion 20, thereby contributing to the development of a sustainable transportation system.

[0080] (4) The notification device 81 notifies the driver of information generated based on the determination result by the grip determination device 60. As a result, for example, if the driver is not gripping the rim portion 20 or if a foreign object is in contact with the rim portion 20, the driver can be prompted to grip the rim portion 20 properly or to remove the foreign object, thereby supporting safe driving by the driver.

[0081] (5) The alarm device 81 changes the alarm mode depending on whether it is determined that the rim portion 20 is not being gripped based on the capacitance measurement values ​​Ch_R, Ch_L, Ch_U, and Ch_D, or whether it is determined that the rim portion 20 is not being gripped because the absolute value of the steering torque detection value Tr_d remains below the torque threshold value Tr_th for a period exceeding the time threshold value T_th. This makes it possible to urge the driver to grip the rim portion 20 appropriately or to remove any foreign object that is estimated to be in contact with the rim portion 20, thereby assisting the driver in driving safely.

[0082] (6) The safe driving skill evaluation device 82 evaluates the driving skill of the driver based on the judgment result by the grip judgment device 60. This makes it possible to evaluate the driving skill by distinguishing, for example, between a case where the driver is not gripping the rim portion 20 properly and a case where a foreign object is in contact with the rim portion 20, thereby supporting the driver in safe driving.

[0083] (7) The automatic driving device 83 changes the automatic driving level based on the judgment result by the grip judgment device 60. This makes it possible to distinguish between a case where the driver is not gripping the rim portion 20 and a case where a foreign object is in contact with the rim portion 20 and change the automatic driving level accordingly, thereby supporting safe driving by the driver.

[0084] Although one embodiment of the present invention has been described above, the present invention is not limited to this embodiment. The detailed configuration may be appropriately changed within the scope of the spirit of the present invention.

[0085] For example, in the above embodiment, the rim portion 20 is divided into four grip portions 20R, 20L, 20U, and 20D, and the grip sensor unit 6 determines whether or not each grip portion 20R, 20L, 20U, and 20D is being gripped based on the capacitance measurement values ​​Ch_R, Ch_L, Ch_U, and Ch_D of each electrode portion 60R, 60L, 60U, and 60D provided near each grip portion 20R, 20L, 20U, and 20D, but the present invention is not limited to this. That is, the position where each electrode portion is provided is not limited to the rim portion 20, and it may be provided on the spoke portion 25L, 25R, and 25D or the hub portion 23. Furthermore, the number of electrodes provided on the steering wheel 2 is not limited to four, and may be one to three or five or more. [Explanation of symbols]

[0086] 1...Steering device 2. Steering handle 20…Rim section 20R, 20L, 20U, 20D…Grip section 22...Lower end 23…Hub section 25L, 25R, 25D…Spoke section 31...Torque sensor 6...Grip sensor unit 60...Grip determination device 60R,60L,60U,60D…Electrode part 62R, 62L, 62U, 62D...Measuring circuit (measuring device) 8...Control device group 81...Alarm device 82...Safe driving skill evaluation device 83...Automatic driving device 9. Safe driving support system

Claims

1. a steering wheel that receives steering operation of the vehicle by a driver; a torque sensor for detecting a steering torque acting on the steering wheel; a measuring device for measuring the capacitance of an electrode portion provided on the steering wheel; A steering device including a grip determination device that determines whether the steering wheel is being gripped and acquires a grip position on a rim portion of the steering wheel, The gripping determination device determines that the steering wheel is being gripped based on the measurement results by the measuring device, and then, if the state in which the absolute value of the torque detection value by the torque sensor is less than a predetermined torque threshold continues for more than a predetermined time threshold, determines that the steering wheel is not being gripped, and changes either or both of the torque threshold and the time threshold based on the gripping position.

2. The steering device according to claim 1 ; A safe driving support system comprising: a control device group communicatively connected to the gripping determination device.

3. 3. The safe driving support system according to claim 2, wherein the control device group includes a notification device that notifies a driver of information generated based on a result of the determination by the grip determination device.

4. The safety driving support system according to claim 3, characterized in that the notification device changes the notification manner depending on whether it is determined that the steering wheel is not being gripped based on the measurement results or whether it is determined that the steering wheel is not being gripped in accordance with the state in which the absolute value of the torque detection value is less than the torque threshold value continuing beyond the time threshold value.

5. 3. The safe driving support system according to claim 2, wherein the control device group includes a safe driving skill evaluation device that evaluates the safe driving skill of a driver based on a result of the judgment by the grip judgment device.

6. The control device group includes an autonomous driving device that executes autonomous driving control according to a plurality of autonomous driving levels, The safe driving support system according to claim 2, characterized in that the automatic driving device changes the automatic driving level based on a judgment result by the grip judgment device.

Images