Steering device and safe driving support system

Abstract

To provide a steering device that can estimate not only gripping of a rim part by a driver but also a gripping position of the rim part, in order to improve traffic safety.SOLUTION: A steering device, which receives steering operation by a driver, is provided with: a steering handle which comprises a toric rim part, a hub part provided inside the rim part, and a spoke part extending along a radial direction of the rim part to connect the hub part to a rim inner periphery part; an electrode provided in the steering handle; an electrostatic capacity measuring part that measures an electrostatic capacity of the electrode; and a gripping detection part that detects gripping of the rim part by the driver on the basis of a measured value Ch_d of the electrostatic capacity by the electrostatic capacity measuring part. The gripping detection part estimates a gripping position in the rim part on the basis of a convergence value Ch_cnv of the measured value Ch_d of the electrostatic capacity.SELECTED DRAWING: Figure 4B

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 that accepts steering operations of a vehicle by a driver and a safe driving support system that uses the steering device to support safe driving by the driver. [Background technology]

[0002] In recent years, in order to improve traffic safety, vehicles have been increasingly equipped with driving assistance devices that assist drivers in driving the vehicle, such as a lane keeping function, a lane departure prevention function, a lane change function, and a leading vehicle following function. In vehicles equipped with such driving assistance devices, a grip detection device such as that shown in Patent Document 1 detects whether the driver is gripping the steering wheel, and if it is detected that the driver is not gripping the steering wheel, the device may prompt the driver to grip the steering wheel or cancel any driving assistance functions that are currently being executed.

[0003] The grip detection device disclosed in Patent Document 1 measures the capacitance of electrodes provided on the rim of the steering wheel, and detects whether the driver is gripping the steering wheel based on this capacitance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-87566 Summary of the Invention [Problem to be solved by the invention]

[0005] The rim of a typical steering wheel is circular, and the driver can basically grip the entire rim. However, recommended grip positions are set on the rim to allow the driver to steer appropriately in response to changes in the surrounding traffic environment. In many cases, these recommended grip positions are set near the bases of the left and right spokes of the rim, more specifically, at the 3 o'clock and 9 o'clock positions when the rim is likened to a clock.

[0006] However, the conventional steering device described in Patent Document 1 can detect whether the driver is gripping the rim, but cannot detect the grip position. Therefore, the steering device described in Patent Document 1 cannot detect whether the driver is gripping the rim at the recommended grip position.

[0007] The present invention aims to provide a steering device that can estimate not only the driver's grip on the rim but also the grip position, in order to improve traffic safety, and a safe driving support system that uses this steering device to support the driver in safe driving. [Means for solving the problem]

[0008] (1) A steering device according to the present invention accepts steering operations by a driver and comprises a steering wheel having an annular rim portion, a hub portion provided inside the rim portion, and spoke portions extending radially along the rim portion and connecting the hub portion to the inner rim portion of the rim portion; electrodes provided on the steering wheel; a measuring unit that measures the capacitance of the electrodes; and a grip detection unit that detects the driver's grip on the rim portion based on the capacitance measurement value by the measuring unit, wherein the grip detection unit estimates the grip position on the rim portion based on the convergence value of the capacitance measurement value.

[0009] (2) In this case, it is preferable that the grip detection unit acquires the capacitance measurement value when the fluctuation range of the capacitance measurement value is less than a predetermined convergence judgment value for a predetermined judgment time as the convergence value, and detects gripping of the rim portion when the convergence value is equal to or greater than the predetermined grip judgment value.

[0010] (3) In this case, it is preferable that the electrodes are provided on the steering wheel in the vicinity of a recommended grip position within a grip detection range determined for the rim portion.

[0011] (4) In this case, it is preferable that the recommended gripping position is determined at a portion of the rim that includes a spoke connection portion to which the spoke is connected, and that the electrode is provided on the spoke.

[0012] (5) In this case, it is preferable that the grip detection unit estimates, as the grip position, a position farther away from the recommended grip position as the convergence value becomes smaller.

[0013] (6) The safety driving support system according to the present invention is characterized by comprising a steering device described in any one of (1) to (5) and a control device group communicatively connected to the grip detection unit.

[0014] (7) In this case, it is preferable that the control device group includes a driver notification device that notifies the driver of information generated based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

[0015] (8) In this case, it is preferable that the control device group includes a fatigue level estimation device that estimates the driver's fatigue level based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

[0016] (9) In this case, it is preferable that the control device group includes a driving posture evaluation device that evaluates the driver's driving posture based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

[0017] (10) In this case, the control device group preferably includes a driving assistance device that executes driving assistance control to assist the driver in operating the vehicle, and the driving assistance device preferably cancels the driving assistance control that is currently being executed based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

[0018] (11) In this case, it is preferable that the control device group includes an automatic driving device that executes automatic driving control according to multiple automatic driving levels, and that the automatic driving device changes the automatic driving level based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position. [Effects of the Invention]

[0019] (1) A steering device includes a steering wheel having a rim, a hub, and spokes; electrodes provided on the steering wheel; a measurement unit that measures the capacitance of the electrodes; and a grip detection unit that detects the driver's grip on the rim based on the capacitance measurement value by the measurement unit and estimates the grip position based on the convergence value of the capacitance measurement value. Here, the capacitance measurement value changes depending on the relative position of the driver's hand with respect to the electrodes provided on the steering wheel. Therefore, when the driver approaches the rim and grips the rim, the relative position of the hand gripping the rim with respect to the electrode is fixed, and it is thought that the capacitance measurement value converges to a value corresponding to the grip position on the rim. In this invention, the grip detection unit can estimate the driver's grip position on the rim by utilizing the above-mentioned characteristic change in the capacitance measurement value when gripping, thereby improving traffic safety.

[0020] (2) The grip detection unit acquires the capacitance measurement value when the fluctuation range of the capacitance measurement value is less than a predetermined convergence judgment value for a predetermined judgment time as a convergence value, and detects the grip of the rim part when this convergence value is equal to or greater than the grip judgment value. This allows the grip detection unit to accurately detect the driver's grip of the rim part, thereby improving traffic safety.

[0021] (3) The grip detection unit has electrodes located on the steering wheel near the recommended grip position within a grip detection range defined for the rim. This allows the capacitance measurement value to peak when the driver grips the rim at the recommended grip position, making it possible to estimate whether the driver is gripping the rim at the recommended grip position, thereby improving traffic safety.

[0022] (4) The grip detection unit determines a recommended grip position on the rim, including the spoke connection portion where the spokes are connected, and provides electrodes on the spokes near this recommended grip position. This allows the capacitance measurement value to peak when the driver grips the rim at the recommended grip position, and also makes it possible to detect gripping of the rim over a wide range, thereby improving traffic safety.

[0023] (5) The smaller the convergence value, the more the grip detection unit estimates the grip position, which is farther away from the recommended grip position. This allows the driver's grip position on the rim to be estimated with high accuracy based on the recommended grip position, thereby improving traffic safety.

[0024] (6) The safe driving support system includes a steering device and a control device group communicably connected to a grip detection unit of the steering device. This allows the control device group to support safe driving by the driver based on the grip detection result of the rim portion and the grip position estimation result by the grip detection unit, thereby improving traffic safety.

[0025] (7) The driver notification device notifies the driver of information generated based on the detection result of the grip detection unit for gripping the rim and the estimation result of the grip position. As a result, for example, if the grip position is inappropriate, the device can notify the driver that the grip position is inappropriate or urge the driver to grip the rim at the recommended grip position, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0026] (8) As the driver's fatigue accumulates, the grip position tends to change frequently, and therefore there is a correlation between the grip position and the driver's fatigue level. The fatigue level estimation device can accurately estimate the driver's fatigue level by utilizing this correlation between the fatigue level and changes in the grip position, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0027] (9) There is a correlation between the driver's posture and the grip position. By utilizing this correlation between posture and grip position, the driving posture evaluation device can accurately estimate the driver's driving posture, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0028] (10) The driving assistance device cancels the driving assistance control in progress based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position. This allows the driving assistance control in progress to be canceled at an appropriate timing taking into account the gripping position of the rim portion by the driver, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0029] (11) The autonomous driving device changes the autonomous driving level based on the detection result of the grip detection unit for gripping the rim and the estimation result of the grip position. This allows the autonomous driving level to be changed at an appropriate time taking into account the driver's grip position on the rim, thereby supporting safe driving by the driver and ultimately improving traffic safety. [Brief explanation of the drawings]

[0030] [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 this steering device; [Figure 2] FIG. 10 is a diagram schematically illustrating a grip detection range by a left electrode and a right electrode. [Figure 3] FIG. 2 is a diagram showing a circuit configuration of a grip detection device. [Figure 4A] FIG. 2 is a view showing the upper right side of the steering wheel including the right spoke portion as seen from the driver. [Figure 4B] 10 is a diagram showing an example of a change over time in capacitance measured by a capacitance measuring unit. FIG. [Figure 5] FIG. 10 is a diagram illustrating an example of a grip position estimation map that associates a capacitance convergence value with a grip position. DETAILED DESCRIPTION OF THE INVENTION

[0031] 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.

[0032] 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.

[0033] 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 uses the steering device 1 and the control device group 8 to support the driver in safe driving of the vehicle.

[0034] In this embodiment, the devices 81 to 84 constituting the control device group 8 are described as in-vehicle devices that can communicate 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 84 constituting the control device group 8 may be external devices that can wirelessly communicate with the steering device 1 via an in-vehicle communication device (not shown).

[0035] The steering device 1 includes a steering handle 2 that accepts steering operations of the vehicle by the driver and auxiliary operation of vehicle accessories, a steering shaft 3 that supports the steering handle 2, and a grip detection device 6 that detects the driver's grip of the steering handle 2.

[0036] The steering wheel 2 comprises a circular rim portion 20 that can be gripped by the driver, a hub portion 23 provided inside the rim portion 20, and three spoke portions 25L, 25R, 25D that extend radially from the hub portion 23 and are connected to the inner rim portion 21 of the rim portion 20.

[0037] 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, and constitutes 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 with a steering mechanism that constitutes part of the vehicle body (not shown). Therefore, the steering torque generated when the driver rotates the steering wheel 2 is transmitted to the steering mechanism (not shown) by this steering shaft 3.

[0038] The rim portion 20 and hub portion 23 are connected by three spokes 25L, 25R, and 25D. The left spoke 25L extends horizontally and connects the left portion of the hub portion 23 as seen by the driver to left spoke connection portion 26L, which is the left portion of the rim inner circumferential portion 21 as seen by the driver. The right spoke 25R extends horizontally and parallel to the left spoke 25L and connects the right portion of the hub portion 23 as seen by the driver to right spoke connection portion 26R, which is the right portion of the rim inner circumferential portion 21 as seen by the driver. The lower spoke 25D extends vertically and perpendicular to the spokes 25L and 25R 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.

[0039] 1, a left thumb locking portion 27L is formed as a recessed portion extending radially outward as viewed from the rider on the portion of rim inner circumferential portion 21 that connects with the upper portion of left spoke connection portion 26L as viewed from the rider. Also, a right thumb locking portion 27R is formed as a recessed portion extending radially outward as viewed from the rider on the portion of rim inner circumferential portion 21 that connects with the upper portion of right spoke connection portion 26R as viewed from the rider.

[0040] In the steering device 1 according to this embodiment, the recommended gripping position for the driver's left hand is when the thumb of the left hand is engaged with the left thumb engagement portion 27L and the base of the thumb is in contact with the left spoke connection portion 26L, and the remaining fingers of the left hand grip the rim portion 20. Therefore, the recommended gripping position for the driver's left hand is determined to be the portion of the rim portion 20 that includes the left spoke connection portion 26L.

[0041] Furthermore, in the steering device 1 according to this embodiment, the recommended gripping position for the driver's right hand is when the thumb of the right hand is engaged with the right thumb engagement portion 27R and the base of the thumb is in contact with the right spoke connection portion 26R, and the rim portion 20 is gripped with the remaining fingers of the right hand. Therefore, the recommended gripping position for the driver's right hand is determined to be the portion of the rim portion 20 that includes the right spoke connection portion 26R.

[0042] The left spoke portion 25L and the right spoke portion 25R are provided with a left accessory operation console unit 5L and a right accessory operation console unit 5R, respectively, that accepts accessory operation by the driver to operate vehicle accessories (e.g., an audio device, a car navigation device, etc., not shown). Each of these accessory operation console units 5L, 5R has a rectangular shape when viewed from the driver. The driver can operate the vehicle accessories by operating multiple switches provided on these accessory operation console units 5L, 5R with his / her fingers.

[0043] In the following, the positions of the approximately circular rim portion 20, rim inner periphery 21, hub portion 23, and steering shaft 3 as viewed from the driver, as well as the orientations of the spokes 25L, 25R, and 25D, may be expressed in degrees (°) clockwise from the steering shaft 3 as the center and the upper end 20C of the rim portion 20 as viewed from the driver. That is, the right spoke portion 25R extends along a 90° angle 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° angle 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° angle and connects the 270° portions of the hub portion 23 and the rim inner periphery 21. The recommended gripping position for the driver's left hand is determined to be the 270° position of the rim portion 20. The recommended gripping position for the driver's right hand is determined to be at a 90° angle from the rim portion 20.

[0044] The grip detection device 6 includes a left electrode 60L and a right electrode 60R provided on the steering wheel 2, and a sensor unit 62 electrically connected to these electrodes 60L, 60R.

[0045] The electrodes 60L, 60R are each, for example, plate-shaped and conductive. The left electrode 60L is provided on the steering wheel 2 near a recommended grip position for the left hand within a grip detection range (described later) defined for the rim portion 20. More specifically, the left electrode 60L is provided on the left spoke portion 25L along an upper and radially outer side wall surface of the left accessory operation console unit 5L as viewed from the driver. The right electrode 60R is provided on the steering wheel 2 near a recommended grip position for the right hand within a grip detection range (described later) defined for the rim portion 20. More specifically, the right electrode 60R is provided on the right spoke portion 25R along an upper and radially outer side wall surface of the right accessory operation console unit 5R as viewed from the driver. Note that in this embodiment, a case where the electrodes 60L, 60R are provided on the spoke portions 25L, 25R will be described, but the present invention is not limited thereto.

[0046] The sensor unit 62 is connected to the left electrode 60L and the right electrode 60R via the left wiring 61L and the right wiring 61R. The sensor unit 62 is provided inside the left spoke portion 25L together with the above-mentioned left accessory operation console unit 5L, for example.

[0047] Figure 2 is a diagram showing the grasp detection ranges RL and RR of the electrodes 60L and 60R described above, i.e., the range of electric field lines induced around the electrodes 60L and 60R by applying a predetermined voltage to each of the electrodes 60L and 60R.

[0048] As described above, the left electrode 60L is provided on the left spoke 25L near the recommended gripping position (270°) of the rim 20 for the left hand, and the right electrode 60R is provided on the right spoke 25R near the recommended gripping position (90°) of the rim 20 for the right hand. Therefore, grip detection ranges RL and RR, which correspond to the range of electric field lines induced around these electrodes 60L and 60R by applying a voltage to these electrodes 60L and 60R, include a range of 210° to 330° centered on the recommended gripping position of the rim 20 for the left hand and a range of 30° to 150° centered on the recommended gripping position of the rim 20 for the right hand. In this embodiment, the left electrode 60L and the right electrode 60R are provided near the recommended gripping position of the rim 20 for the left hand and the recommended gripping position of the right hand, respectively, so that dense electric field lines are induced within these grip detection ranges RL and RR at the recommended gripping positions for each hand.

[0049] FIG. 3 is a diagram showing the circuit configuration of the grip detection device 6. As shown in FIG. The sensor unit 62 measures the electrical characteristics of the electrodes 60L, 60R (for example, the capacitance between the electrodes 60L, 60R and ground), and based on the measurement results, detects the driver's grip on the steering wheel 2 and further estimates the driver's grip position on the rim portion 20.

[0050] The sensor unit 62 includes a pulse power supply 63, an amplifier 64, a first switch 65, a second switch 66, a charging capacitor 67, a capacitance measuring unit 68, and a grip detecting unit 69, and uses these to detect the driver's grip on the steering wheel 2. In Fig. 2, the capacitance between the electrodes 60L, 60R and the ground (e.g., 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 stray capacitance Ce formed by a stray capacitor E such as wiring and components excluding the human body H.

[0051] As shown in Figure 2, the pulse power supply 63 and amplifier 64 are connected in series. The second switch 66 and charging capacitor 67 are connected in parallel. The series circuit consisting of the pulse power supply 63 and amplifier 64 and the parallel circuit consisting of the second switch 66 and charging capacitor 67 are connected via a first switch 65. The output terminal of the amplifier 64 and the first switch 65 are connected to the electrodes 60L and 60R via the wirings 61L and 61R. Therefore, the pulse power supply 63 is connected to the electrodes 60L and 60R via the amplifier 64 and the wirings 61L and 61R. The second switch 66 and charging capacitor 67 are connected to the electrodes 60L and 60R via the first switch 65 and the wirings 61L and 61R, respectively.

[0052] The pulse power supply 63 supplies a pulse voltage Vs of a predetermined frequency and a predetermined voltage to the amplifier 64 in response to a command from the capacitance measuring unit 68 or the grip detecting unit 69. The amplifier 64 amplifies the pulse voltage Vs supplied from the pulse power supply 63 and applies it to each of the electrodes 60L, 60R.

[0053] 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 keeps the second switch 66 off until the voltage VCref of the charging capacitor 67 reaches a predetermined threshold Vthr, for example, and then turns the second switch 66 on after the voltage VCref reaches the threshold Vthr, thereby discharging the charge stored in the charging capacitor 67.

[0054] The first switch 65 is a switching element that is turned on / off by a drive circuit (not shown). The drive circuit for this first switch 65 turns off the first switch 65 in response to the rising edge 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 each of the electrodes 60L, 60R, and electric charge moves through the path indicated by the arrow 3a in Figure 2, charging the human body H and the floating capacitor E.

[0055] Furthermore, the drive circuit for 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 3b in Figure 2, charging the charging capacitor 67. This causes the voltage VCref of the charging capacitor 67 to rise.

[0056] Therefore, when a pulse voltage is applied to each electrode 60L, 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, i.e., the relative position of the driver's hand operating the steering wheel 2 with respect to each electrode 60L, 60R. That is, when the driver's hand is gripping a portion of the rim portion 20 within the grip detection ranges RL, RR (see FIG. 2) and the capacitance Ch is high, the time it takes for the voltage VCref of the charging capacitor 67 to reach the threshold value Vthr is short. On the other hand, when the driver's hand is away from the grip detection ranges RL, RR and the capacitance Ch is low, the time it takes for the voltage VCref of the charging capacitor 67 to reach the threshold value Vthr is long.

[0057] The capacitance measuring unit 68 measures the time and number of pulses until the voltage VCref of the charging capacitor 67 reaches the threshold Vthr, and based on this measurement result, indirectly measures the capacitance Ch formed by the human body H present in the vicinity of each of the electrodes 60L, 60R. The capacitance measuring unit 68 transmits the measurement value Ch_d of the capacitance Ch obtained by the above procedure to the grip detection unit 69.

[0058] The grip detection unit 69 detects the driver's gripping of the rim portion 20 based on the capacitance measurement value Ch_d by the capacitance measurement unit 68, and if gripping of the rim portion 20 is detected, estimates the grip position on the rim portion 20.

[0059] Next, the procedure for detecting gripping of the rim portion 20 by the grip detection unit 69 will be described in detail with reference to FIGS. 4A and 4B.

[0060] Fig. 4A is a diagram showing the upper right side as seen from the driver, including the right spoke portion 25R of the steering wheel 2. Note that five arrows C1, C2, C3, C4, and C5 in Fig. 4A each indicate an example of a movement path of the thumb of the driver's right hand, and the circles at the ends of these arrows C1 to C5 indicate the end positions of the thumb of the right hand.

[0061] Fig. 4B is a diagram showing an example of the change over time in the capacitance measurement value Ch_d measured by the capacitance measurement unit 68. More specifically, Fig. 4B shows, with lines L1, L2, L3, L4, and L5, the change over time in the capacitance measurement value Ch_d when the driver's thumb is moved along the movement paths indicated by arrows C1 to C5 in Fig. 4A.

[0062] Arrow C1 in Figure 4A shows the path of movement of the right thumb when the right hand is not gripping the rim portion 20 and the right thumb is maintained in the space between the rim inner circumference 21 of the rim portion 20 and the right spoke portion 25R without supporting the right hand with the rim portion 20. In this case, the relative position of the right thumb with respect to the electrode 60R is not fixed, so the measured capacitance value Ch_d fluctuates slightly, as shown by line L1 in Figure 4B.

[0063] Arrow C2 in Figure 4A shows the path of movement of the right thumb when the right hand is not gripping the rim 20 and is moved radially outward from the outer rim portion of the rim 20. In this case, the right thumb moves outward from within the grip detection range RR of the right electrode 60R, and the distance between the right thumb and electrode 60R increases over time, so that the measured capacitance value Ch_d decreases over time and converges to a range below the predetermined grip determination value Ch_thr, as shown by line L2 in Figure 4B.

[0064] In contrast, arrows C3 to C5 in Fig. 4A indicate the path of movement of the right thumb when the right hand grasps within the grasp detection range RR of rim portion 20. In this case, as shown by lines L3 to L5 in Fig. 4B, the capacitance measurement value Ch_d converges over time to within a range equal to or greater than the grasp determination value Ch_thr.

[0065] Therefore, if the fluctuation range of the capacitance measurement value Ch_d is less than a predetermined convergence judgment value over a predetermined judgment time, the grip detection unit 69 judges that the capacitance measurement value Ch_d has converged, and acquires the capacitance measurement value Ch_d at the time of determining convergence (more specifically, for example, the average value of the capacitance measurement values ​​Ch_d over the judgment time) as the capacitance convergence value Ch_cnv. Furthermore, the grip detection unit 69 detects the driver's grip of the rim portion 20 if the capacitance convergence value Ch_cnv acquired according to the above procedure is equal to or greater than a predetermined grip judgment value Ch_thr. In other words, the grip detection unit 69 detects the driver's grip of the rim portion 20 if the capacitance measurement value Ch_d has converged and the convergence value Ch_cnv is equal to or greater than the grip judgment value Ch_thr. Furthermore, if the capacitance measurement value Ch_d has not converged or if the capacitance convergence value Ch_cnv is less than the grip judgment value Ch_thr, the grip detection unit 69 does not detect the driver's grip of the rim portion 20.

[0066] Next, a procedure for estimating the grip position of the rim portion 20 by the driver using the grip detection unit 69 will be described in detail with reference to FIGS. 4A and 4B.

[0067] As described above, arrows C3 to C5 in Figure 4A all indicate the path of movement of the right thumb when the right hand grips the rim 20 within the grip detection range RR. More specifically, arrow C3 indicates the path of movement of the right thumb when the right thumb approaches the right thumb locking portion 27R from above the right spoke 25R and the rim 20 is gripped with the right hand at the recommended gripping position for the right hand. Arrow C4 indicates the path of movement of the right thumb when the right thumb approaches the rim inner periphery 21 from above the right spoke 25R, slightly above the right thumb locking portion 27R, and the rim 20 is gripped with the right hand at a portion slightly above the recommended gripping position. Arrow C5 indicates the path of movement of the right thumb when it approaches rim inner circumferential portion 21 from above right spoke portion 25R, slightly above the portion indicated by arrow C4, and then grasps rim portion 20 with the right hand at a position even higher than the portion indicated by arrow C4. In other words, when rim portion 20 is being grasped with the right hand, the distance between the right thumb and right electrode 60R increases in the order of arrows C3, C4, and C5.

[0068] Therefore, as shown by lines L3 to L5 in Fig. 4B, when the thumb of the right hand is moved along each of the arrows C3 to C5, the capacitance convergence value Ch_cnv converges within a range equal to or greater than the grip determination value Ch_thr. Furthermore, the capacitance convergence value Ch_cnv at this time decreases in the order of arrows C3, C4, and C5. In this way, the magnitude of the capacitance convergence value Ch_cnv correlates with the grip position on the rim portion 20 by the driver.

[0069] Therefore, the grip detection unit 69 estimates the grip position on the rim portion 20 based on the capacitance convergence value Ch_cnv by utilizing the correlation between the magnitude of the capacitance convergence value Ch_cnv and the grip position as described above.

[0070] More specifically, the grip detection unit 69 estimates the grip position of the driver on the rim portion 20 by searching a map such as the one shown in FIG. 5 based on the capacitance convergence value Ch_cnv.

[0071] Fig. 5 is a diagram showing an example of a grip position estimation map that associates the capacitance convergence value Ch_cnv (horizontal axis) with the grip position (vertical axis). In Fig. 5, the grip position on the rim portion 20 is represented by the distance Y along the radial direction of the rim portion 20 (see arrows Y1 and Y2 in Fig. 4A) from the recommended grip position P0 indicated by a black circle in Fig. 4A.

[0072] As described above, the right electrode 60R is provided in the right spoke part 25R near the recommended gripping position P0. Therefore, the distance between the right electrode 60R and the gripping position tends to increase as the radial distance Y from the recommended gripping position P0 increases. Therefore, as shown in FIG. 5, the smaller the capacitance convergence value Ch_cnv, the longer the distance Y. Therefore, by referring to the gripping position estimation map as shown in FIG. 5, the gripping detection unit 69 estimates the gripping position to be farther from the recommended gripping position P0 as the capacitance convergence value Ch_cnv decreases.

[0073] The grip detection unit 69 transmits the detection result of gripping the rim portion 20 according to the above procedure and the estimation result of the grip position to the control device group 8 (see FIG. 3).

[0074] Returning to FIG. 1, the control device group 8 includes a driver notification device 81, a fatigue level estimation device 82, a driving posture evaluation device 83, and a driving assistance device 84.

[0075] The driver notification device 81 generates support information to support safe driving by the driver based on the detection results of the gripping of the rim portion 20 and the estimation results of the gripping position transmitted from the grip detection section 69 of the sensor unit 62, and notifies the driver of the generated support information via an HMI (Human Machine Interface, not shown) provided in the vehicle. More specifically, if the driver notification device 81 determines that the driver is not gripping the rim portion 20 based on the grip detection results transmitted from the grip detection section 69, the driver notifies the driver of support information urging the driver to grip the rim portion 20 in the recommended gripping position using the HMI through the driver's visual, auditory, tactile, etc. Furthermore, if the driver notification device 81 determines that the driver is not gripping the rim portion 20 in the recommended gripping position based on the estimation results of the gripping position transmitted from the grip detection section 69, the driver notification device 81 notifies the driver of support information urging the driver to grip the rim portion 20 in the recommended gripping position using the HMI.

[0076] The fatigue level estimation device 82 estimates the driver's fatigue level based on the grip detection results of the rim portion 20 and the grip position estimation results transmitted from the grip detection unit 69 of the sensor unit 62. As the driver accumulates fatigue, their grip position may change frequently. For this reason, it can be said that there is a correlation between the change in grip position and the driver's fatigue level. Therefore, the fatigue level estimation device 82 calculates the change in grip position over time by using the grip detection results and the grip position estimation results transmitted from the grip detection unit 69, and estimates the driver's fatigue level based on this change in grip position. Furthermore, if the estimated fatigue level exceeds a predetermined threshold, the fatigue level estimation device 82 notifies the driver via the HMI of support information encouraging the driver to take a break.

[0077] The driving posture evaluation device 83 evaluates the driver's driving posture based on the grip detection results of the rim portion 20 and the grip position estimation results transmitted from the grip detection unit 69 of the sensor unit 62. More specifically, the driving posture evaluation device 83 calculates a recommended grip time corresponding to the time the driver grips the rim portion 20 at the recommended grip position based on the grip detection results and grip position estimation results transmitted from the grip detection unit 69, and if this recommended grip time is equal to or greater than a predetermined threshold, evaluates the driving posture as good, and if the recommended grip time is less than the threshold, evaluates the driving posture as poor. The evaluation results by the driving posture evaluation device 83 may also be notified to the driver via an HMI.

[0078] The driving assistance device 84 is a computer that executes driving assistance control to assist the driver in operating the vehicle. The driving assistance device 84 cancels the driving assistance control that is currently being executed based on the detection result of the grip of the rim portion 20 and the estimation result of the grip position transmitted from the grip detection unit 69 of the sensor unit 62.

[0079] The steering device 1 and the safe driving support system 9 according to this embodiment have the following advantages. (1) The steering device 1 includes a steering wheel 2 having a rim portion 20, a hub portion 23, and spoke portions 25L, 25R, electrodes 60L, 60R provided on the steering wheel 2, a capacitance measurement unit 68 that measures the capacitance of these electrodes 60L, 60R, and a grip detection unit 69 that detects the driver's grip on the rim portion 20 based on a capacitance measurement value Ch_d measured by the capacitance measurement unit 68 and estimates the grip position based on a convergence value Ch_cnv of the capacitance measurement value Ch_d. Here, the capacitance measurement value Ch_d changes depending on the relative position of the driver's hand with respect to the electrodes 60L, 60R provided on the steering wheel 2. Therefore, when the driver approaches the rim portion 20 and grips the rim portion 20, the relative position of the hand gripping the rim portion 20 with respect to the electrodes 60L, 60R is fixed, and it is thought that the capacitance measurement value Ch_d converges to a value corresponding to the grip position on the rim portion 20. In the steering device 1, the grip detection unit 69 can estimate the grip position of the rim portion 20 by the driver by utilizing the above-mentioned characteristic change in the capacitance measurement value Ch_d when gripping, thereby improving traffic safety.

[0080] (2) The grip detection unit 69 acquires the capacitance measurement value Ch_d when the fluctuation range of the capacitance measurement value Ch_d is less than a predetermined convergence judgment value for a predetermined judgment time as a convergence value Ch_cnv, and if this convergence value Ch_cnv is equal to or greater than the grip judgment value Ch_thr, it detects the grip of the rim portion 20. This allows the grip detection unit 69 to accurately detect the driver's grip of the rim portion 20, thereby improving traffic safety.

[0081] (3) The grip detection unit 69 provides electrodes 60L, 60R near the recommended grip position within grip detection ranges RL, RR defined for the rim 20 of the steering wheel 2. This allows the capacitance measurement value Ch_d to peak when the driver grips the rim 20 at the recommended grip position, making it possible to estimate whether the driver is gripping the rim 20 at the recommended grip position, thereby improving traffic safety.

[0082] (4) The grip detection unit 69 determines the recommended grip position at a portion of the rim 20 that includes the spoke connection portions 26L, 26R where the spokes 25L, 25R are connected, and the electrodes 60L, 60R are provided on the spokes 25L, 25R near this recommended grip position. This makes it possible to detect gripping of the rim 20 over a wide range while ensuring that the capacitance measurement value Ch_d peaks when the driver grips the rim 20 at the recommended grip position, thereby improving traffic safety.

[0083] (5) The smaller the convergence value, the more the grip detection unit estimates the grip position, which is farther away from the recommended grip position. This allows the driver's grip position on the rim to be estimated with high accuracy based on the recommended grip position, thereby improving traffic safety.

[0084] (6) The safe driving support system 9 includes a steering device 1 and a control device group 8 that is communicatively connected to a grip detection unit 69 of the steering device 1. As a result, the control device group 8 can support safe driving by the driver based on the detection result of the grip of the rim portion 20 by the grip detection unit 69 and the estimation result of the grip position, thereby improving traffic safety.

[0085] (7) The driver notification device 81 notifies the driver of support information generated based on the detection result of the gripping of the rim portion 20 by the grip detection unit 69 and the estimation result of the gripping position. As a result, for example, if the gripping position is inappropriate, the device can notify the driver that the gripping position is inappropriate or urge the driver to grip the rim portion 20 in the recommended gripping position, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0086] (8) The fatigue level estimation device 82 can accurately estimate the driver's fatigue level by utilizing the correlation between the fatigue level and changes in grip position as described above, thereby assisting the driver in safe driving and ultimately improving traffic safety.

[0087] (9) The driving posture evaluation device 83 can accurately estimate the driver's driving posture by utilizing the correlation between the driving posture and the grip position, thereby assisting the driver in safe driving and ultimately improving traffic safety.

[0088] (10) The driving assistance device 84 cancels the driving assistance control that is being executed based on the detection result of the gripping of the rim portion 20 by the grip detection unit 69 and the estimation result of the gripping position. This makes it possible to cancel the driving assistance control that is being executed at an appropriate timing taking into account the gripping position of the rim portion by the driver, thereby supporting safe driving by the driver and ultimately improving traffic safety.

[0089] Although one embodiment of the present invention has been described above, the present invention is not limited to this, and the detailed configuration may be modified as appropriate within the scope of the spirit of the present invention.

[0090] For example, in the above embodiment, a case has been described in which the steering device 1 is connected to the driving assistance device 84, but the present invention is not limited to this. For example, instead of the driving assistance device 84, an automatic driving device that executes automatic driving control according to a plurality of automatic driving levels may be connected to the steering device 1. In this case, it is preferable that the automatic driving device changes the automatic driving level based on the detection result of the grip of the rim portion 20 and the estimation result of the grip position transmitted from the grip detection section 69 of the sensor unit 62. This makes it possible to change the automatic driving level at an appropriate timing taking into account the grip position of the rim portion 20 by the driver, thereby supporting safe driving by the driver. [Explanation of symbols]

[0091] 1...Steering device 2...Steering wheel 20...Rim section 21...Inner rim 23...Hub section 25L...Left spoke 25R...Right spoke 26L…Left spoke connection 26R…Right spoke connection 27L...Left thumb lock 27R...Right thumb lock 6...Grip detection device 60L…Left electrode 60R…Right electrode 62...Sensor unit 68...Capacitance measuring unit (measuring unit) 69...Grip detection unit 8...Control device group 81...Driver notification device 82...Fatigue level estimation device 83...Driving posture evaluation device 84...Driving assistance device 9...Safety driving support system

Claims

1. A steering device that accepts steering operations by a driver, a steering wheel including an annular rim portion, a hub portion provided inside the rim portion, and spoke portions extending along the radial direction of the rim portion and connecting the hub portion and an inner rim portion of the rim portion; an electrode provided on the steering wheel; a measuring unit for measuring the capacitance of the electrode; a grip detection unit that detects gripping of the rim portion by a driver based on the capacitance measurement value by the measurement unit, The electrode is provided on the steering wheel in the vicinity of a recommended grip position within a grip detection range determined for the rim portion, The steering device is characterized in that the grip detection unit estimates a position on the rim portion that is farther away from the recommended grip position as the convergence value of the capacitance measurement value becomes smaller.

2. The steering device according to claim 1, characterized in that the grip detection unit acquires the capacitance measurement value when the fluctuation range of the capacitance measurement value is less than a predetermined convergence judgment value for a predetermined judgment time as the convergence value, and detects gripping of the rim portion when the convergence value is equal to or greater than the predetermined grip judgment value.

3. the recommended gripping position is determined in a portion of the rim portion including a spoke connection portion to which the spoke portion is connected, 2. The steering device according to claim 1, wherein the electrodes are provided on the spoke portions.

4. A steering device according to any one of claims 1 to 3; a control device group communicably connected to the grip detection unit.

5. The safety driving support system according to claim 4, characterized in that the control device group includes a driver notification device that notifies the driver of information generated based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

6. The safety driving support system according to claim 4 or 5, characterized in that the control device group includes a fatigue level estimation device that estimates the driver's fatigue level based on the detection result of the grip of the rim portion by the grip detection unit and the estimation result of the grip position.

7. A safety driving support system as described in any one of claims 4 to 6, characterized in that the control device group includes a driving posture evaluation device that evaluates the driver's driving posture based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

8. the control device group includes a driving assistance device that executes driving assistance control to assist a driver in operating the vehicle, A safe driving support system as described in any one of claims 4 to 7, characterized in that the driving support device cancels the driving support control currently being performed based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

9. The control device group includes an autonomous driving device that executes autonomous driving control according to a plurality of autonomous driving levels, A safety driving support system as described in any one of claims 4 to 7, characterized in that the automatic driving device changes the automatic driving level based on the detection result of the gripping of the rim portion by the grip detection unit and the estimation result of the gripping position.

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