Steering device

Abstract

To provide a steering device that is able to appropriately determine whether or not a steering wheel is gripped, regardless of the body type of a driver.SOLUTION: A steering device 1 includes: a steering wheel 2 configured to receive a steering operation of a vehicle by a driver; a plurality of proximity sensors 4, 5, 6, 7 disposed on a rim portion 20 which can be gripped by the driver in the steering wheel 2, and configured to output detection values Ch_1, Ch_2, Ch_3, Ch_4 which increase and decrease according to distances between respective disposed positions and a human body; and a grip determination device 8 configured to determine whether or not the rim portion 20 is gripped, based on the detection values Ch_1 to Ch_4 of the proximity sensors 4 to 7. The grip determination device 8 includes: a selection unit 81 configured to select a target sensor from among the plurality of proximity sensors 4 to 7, based on degrees of changes in the detection values of the plurality of proximity sensors 4 to 7; and a determination unit 82 configured to determine whether or not the rim portion 20 is gripped, based on the detection value of the target sensor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a steering device, and more particularly to a steering device including a steering wheel and a grip determination device that determines whether or not a driver is gripping the steering wheel. [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 preceding vehicle following function. In vehicles equipped with such driving assistance devices, a grip determination device, such as that shown in Patent Document 1, determines whether the driver is gripping the steering wheel, and if it determines 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 function currently being executed.

[0003] The grip determination device disclosed in Patent Document 1 determines whether or not the driver is gripping the steering wheel based on the detection value of a proximity sensor provided on the rim of the steering wheel. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-69902 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when determining whether or not the steering wheel is being gripped based on the detection value of a proximity sensor provided on the rim, as in the grip determination device shown in Patent Document 1, if any part of the driver's body other than the hands is near the steering wheel, it may be erroneously determined that the driver is gripping the rim even though they are not. More specifically, the larger the driver's physique, the narrower the distance between the steering wheel and the driver's abdomen or knees, making such an erroneous determination more likely to occur.

[0006] An object of the present invention is to provide a steering device that can appropriately determine whether or not the steering wheel is being gripped, regardless of the physique of the driver. [Means for solving the problem]

[0007] (1) A steering device according to the present invention (for example, steering device 1 described later) includes a steering handle (for example, steering handle 2 described later) that accepts steering operation of the vehicle by the driver, a plurality of proximity sensors (for example, first proximity sensor 4, second proximity sensor 5, third proximity sensor 6, and fourth proximity sensor 7 described later) that are arranged on a grip portion of the steering handle that can be gripped by the driver (for example, rim portion 20 described later) and output detection values ​​that increase or decrease depending on the distance between each position and the human body, and a grip determination device (for example, grip determination device 8 described later) that determines whether or not the grip portion is being gripped based on the detection values ​​of the proximity sensors, and the grip determination device is characterized by including a selection unit (for example, selection unit 81 described later) that selects a target sensor from the plurality of proximity sensors based on the degree of change in the detection values ​​of the plurality of proximity sensors, and a determination unit (for example, determination unit 82 described later) that determines whether or not the grip portion is being gripped based on the detection values ​​of the target sensor.

[0008] (2) In this case, it is preferable that the selection unit selects the target sensor by comparing the magnitude of the degree of change in the detection values ​​of the plurality of proximity sensors with each other.

[0009] (3) In this case, it is preferable that the selection unit selects M (M is an integer greater than or equal to 1 and less than N) of the N proximity sensors (N is an integer greater than or equal to 2) in descending order of the degree of change as the target sensors.

[0010] (4) In this case, it is preferable that the selection unit selects the target sensor by comparing the degree of change in the detection values ​​of the plurality of proximity sensors with a selection threshold that is a threshold set for the degree of change.

[0011] (5) In this case, it is preferable that the selection unit selects, as the target sensor, one of the plurality of proximity sensors whose degree of change is greater than the selection threshold value.

[0012] (6) In this case, it is preferable that the selection unit executes a selection process for selecting the target sensor from the plurality of proximity sensors at a predetermined cycle while the determination unit determines that the gripping unit is not being gripped.

[0013] (7) In this case, it is preferable that the judgment unit judges whether the gripping portion is being grasped at each predetermined cycle, and if it judges that the gripping portion was not being grasped in the previous cycle, judges whether the gripping portion is being grasped based on the detection values ​​of only the proximity sensors selected as the target sensor among the multiple proximity sensors, and if it judges that the gripping portion was being grasped in the previous cycle, judges whether the gripping portion is being grasped based on the detection values ​​of the multiple proximity sensors.

[0014] (8) In this case, it is preferable that the determination unit determines that the gripping portion is being gripped when the detection value of the target sensor is equal to or greater than a gripping threshold, which is a threshold value set for the detection value.

[0015] (9) In this case, it is preferable that the determination unit determines that the gripping portion is being gripped when the total value of the detection values ​​of the plurality of target sensors is equal to or greater than a gripping threshold, which is a threshold value set for the detection values. [Effects of the Invention]

[0016] (1) In the present invention, multiple proximity sensors are provided in a grip portion of the steering wheel that can be gripped by the driver. If the driver's physique is larger than average, parts of the driver's body, such as the abdomen or knees, will approach specific parts of the grip portion while seated in the driver's seat. Therefore, the detection values ​​of the proximity sensors located near these specific parts will be constantly larger than average, but will not change significantly during driving. In contrast, the detection values ​​of the proximity sensors located near the parts where the driver grips the steering wheel will change significantly each time the driver grips the steering wheel. Therefore, a selection unit of the grip determination device selects a target sensor from among the multiple proximity sensors based on the degree of change in the detection values ​​of the multiple proximity sensors, and a determination unit of the grip determination device determines whether the steering wheel is being gripped based on the detection value of the selected target sensor. According to the present invention, it is possible to exclude from the target sensors those proximity sensors whose detection values ​​are large due to the driver's physique. This makes it possible to appropriately determine whether the steering wheel is being gripped regardless of the driver's physique, thereby improving traffic safety.

[0017] (2) In the present invention, the selection unit selects a target sensor from among the multiple proximity sensors by comparing the degree of change in the detection values ​​of the multiple proximity sensors with each other, and can select as the target sensor from among the multiple proximity sensors one that is located near the point where the driver holds it with his hand.

[0018] (3) In the present invention, the selection unit selects M of the N proximity sensors as target sensors in descending order of the degree of change, thereby selecting from the multiple proximity sensors the one that is located near the point where the driver holds it with his hand as the target sensor.

[0019] (4) In the present invention, the selection unit selects a target sensor from among the multiple proximity sensors by comparing the degree of change in the detection values ​​of the multiple proximity sensors with a selection threshold, which is a threshold value set for this degree of change, and can select as the target sensor from among the multiple proximity sensors one that is located near the point where the driver holds it with his hand.

[0020] (5) In the present invention, the selection unit selects as the target sensor one of the plurality of proximity sensors whose degree of change is greater than the selection threshold, thereby being able to select as the target sensor one of the plurality of proximity sensors that is located near the point where the driver holds the sensor with his / her hand.

[0021] (6) In the present invention, the selection unit executes a selection process to select a target sensor from a plurality of proximity sensors at a predetermined interval while the determination unit determines that the sensor is not being grasped. This enables the selection of an appropriate target sensor to be reselected each time the driver re-grabs the gripping portion or changes the gripping location.

[0022] (7) In the present invention, the determination unit determines whether the grip is being held at the grip portion at each predetermined cycle, and if it determines that the grip was not being held at the previous cycle, it determines whether the grip is being held at the grip portion based on the detection values ​​of only the sensors selected as the target sensors by the selection unit, thereby enabling accurate determination of whether the driver is holding the grip. Furthermore, if it determines that the grip was being held at the previous cycle, it determines whether the grip is being held at the grip portion based on the detection values ​​of multiple proximity sensors, thereby enabling appropriate determination of whether the driver is holding the grip portion even if, for example, the driver slides the grip portion while holding it.

[0023] (8) In the present invention, the judgment unit determines that the gripping portion is being grasped when the detection value of the target sensor is equal to or greater than the gripping threshold, which is a threshold value set for this detection value, thereby making it possible to accurately determine that the driver is grasping the vicinity of the location of the target sensor.

[0024] (9) In the present invention, the determination unit determines that the gripping portion is being grasped when the sum of the detection values ​​of the multiple target sensors is equal to or greater than a gripping threshold, which is a threshold value set for the detection values. This makes it possible to accurately determine whether the gripping portion is being grasped even when, for example, the driver is grasping an object across multiple proximity sensor locations. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a diagram showing a configuration of a steering device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating a circuit configuration of a first detection circuit. [Figure 3] 10 is a flowchart showing a procedure for determining whether or not the rim portion is being gripped by the driver based on detection values ​​of a plurality of proximity sensors in the grip determination device. [Figure 4] 10 is a flowchart showing a specific procedure of a first grip determination process. [Figure 5] 10 is a flowchart showing a specific procedure of a second grip determination process. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A steering device according to an embodiment of the present invention will be described below with reference to the drawings.

[0027] 1 is a diagram showing the configuration of a steering device 1 according to this embodiment. The steering device 1 is mounted on a vehicle (not shown). The steering device 1 includes a steering wheel 2 that receives vehicle steering operations and auxiliary device operations by the driver, a steering shaft 3 that pivotally supports the steering wheel 2, a plurality of proximity sensors 4, 5, 6, and 7 (four in this embodiment) provided on the steering wheel 2, and a grip determination device 8 that determines whether the driver is gripping the steering wheel 2 based on the detection results of the proximity sensors 4 to 7.

[0028] The steering wheel 2 has a circular rim portion 20 as a gripping portion that can be gripped by the driver, a hub portion 23 provided inside the rim portion 20, and three spoke portions 25L, 25R, 25D extending radially from the hub portion 23 and connected to the rim inner peripheral portion 21 of the rim portion 20.

[0029] 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.

[0030] The rim portion 20 and the hub portion 23 are connected by three spokes 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 with the left portion of the rim inner periphery 21 as seen by the driver. The right spoke portion 25R extends horizontally and parallel to the left spoke portion 25L and connects the right portion of the hub portion 23 as seen by the driver with the right portion of the rim inner periphery 21 as seen by the driver. The lower spoke portion 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 with the lower portion of the rim inner periphery 21 as seen by the driver.

[0031] As described above, the rim portion 20 has a circular shape when viewed from the driver, and can be gripped by the driver along its entire circumference. The rim portion 20 also has electrode portions 40, 50, 60, and 70 of a plurality of proximity sensors 4, 5, 6, and 7, which will be described later, provided along its entire circumference.

[0032] 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 accept accessory operation 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.

[0033] 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 by the driver, and the orientations of each spoke portion 25L, 25R, 25D may also be expressed in degrees (°) clockwise from the steering shaft 3 as the center and the upper end portion 20C of the rim portion 20 as viewed by 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 hub portion 23 and the 270° portions of the rim inner periphery 21.

[0034] The first proximity sensor 4 includes a first electrode 40 provided on the rim 20 and a first detection circuit 42 electrically connected to the first electrode 40. The first electrode 40 is arc-shaped and extends along the rim 20, and is conductive. The first electrode 40 is provided inside the rim 20. The first electrode 40 is positioned within the rim 20 in a range of approximately 90° between 45° and 135° (i.e., a range that can be held primarily with the driver's right hand). Note that, hereinafter, the position of the first electrode 40 on the rim 20 is also referred to as the right rim portion 20R. The first detection circuit 42 is connected to the first electrode 40 via wiring 41. The first detection circuit 42 detects the capacitance between the first electrode 40 and ground as a value that increases or decreases depending on the distance between the position of the first electrode 40 and the human body. The closer the distance between the position of the first electrode unit 40 and the human body, the larger the capacitance between the first electrode unit 40 and the ground. The capacitance detection value Ch_1 by the first detection circuit 42 is transmitted to the grip determination device 8.

[0035] FIG. 2 is a diagram showing the circuit configuration of the first detection circuit 42. As shown in FIG. The first detection circuit 42 includes a pulse power supply 43, an amplifier 44, a first switch 45, a second switch 46, a charging capacitor 47, and a capacitance measuring unit 48. In Fig. 2, the capacitance between the first electrode unit 40 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 stray capacitance Ce formed by a stray capacitor E such as wiring and components excluding the human body H.

[0036] As shown in Figure 2, the pulse power supply 43 and amplifier 44 are connected in series. The second switch 46 and charging capacitor 47 are connected in parallel. The series circuit consisting of the pulse power supply 43 and amplifier 44 and the parallel circuit consisting of the second switch 46 and charging capacitor 47 are connected via a first switch 45. The output terminal of the amplifier 44 and the first switch 45 are connected to the first electrode unit 40 via wiring 41. Therefore, the pulse power supply 43 is connected to the first electrode unit 40 via the amplifier 44 and wiring 41. Furthermore, the second switch 46 and charging capacitor 47 are connected to the first electrode unit 40 via the first switch 45 and wiring 41, respectively.

[0037] In response to a command from the grip determination device 8, the pulse power supply 43 supplies a pulse voltage Vs of a predetermined frequency and a predetermined voltage to the amplifier 44. The amplifier 44 amplifies the pulse voltage Vs supplied from the pulse power supply 43 and applies it to the first electrode unit 40.

[0038] The second switch 46 is a switching element that is turned on / off by a drive circuit (not shown). The drive circuit for the second switch 46 keeps the second switch 46 off until the voltage VCref of the charging capacitor 47 reaches a predetermined threshold Vthr, for example, and then turns the second switch 46 on after the voltage VCref reaches the threshold Vthr, thereby discharging the charge stored in the charging capacitor 47.

[0039] The first switch 45 is a switching element that is turned on / off by a drive circuit (not shown). The drive circuit for this first switch 45 turns off the first switch 45 in response to the rising edge of the pulse voltage Vs of the pulse power supply 43. As a result, the pulse voltage supplied from the pulse power supply 43 and the amplifier 44 is applied to the first electrode unit 40, and electric charge moves through the path indicated by the arrow 2a in FIG. 2, charging the human body H and the floating capacitor E.

[0040] Furthermore, the drive circuit for the first switch 45 turns on the first switch 45 in response to the falling edge of the pulse voltage Vs of the pulse power supply 43. This connects the human body H and the floating capacitor E to the charging capacitor 47, and charge moves from the human body H and the floating capacitor E to the charging capacitor 47 via the path indicated by the arrow 2b in Figure 2, thereby charging the charging capacitor 47. This causes the voltage VCref of the charging capacitor 47 to rise.

[0041] Therefore, when a pulse voltage is applied to the first electrode unit 40 by the pulse power supply 43 and the amplifier 44, charging and discharging of the human body H and the floating capacitor E are repeated alternately, and the voltage VCref of the charging capacitor 47 gradually increases. At this time, the time until the voltage VCref of the charging capacitor 47 reaches the threshold Vthr (or the number of pulses of the pulse power supply 43) varies depending on the capacitance Ch formed by the human body H, i.e., the distance between the first electrode unit 40 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 first electrode unit 40 on the rim unit 20 and the capacitance Ch is high, the time until the voltage VCref of the charging capacitor 47 reaches the threshold Vthr becomes shorter, whereas when a part of the driver's body is far from the position of the first electrode unit 40 and the capacitance Ch is low, the time until the voltage VCref of the charging capacitor 47 reaches the threshold Vthr becomes longer.

[0042] The capacitance measuring unit 48 measures the time and the number of pulses until the voltage VCref of the charging capacitor 47 reaches the threshold value Vthr, and based on this measurement result, indirectly measures the capacitance Ch formed by the human body H present in the vicinity of the first electrode unit 40. The capacitance measuring unit 48 transmits the detection value Ch_1 of the capacitance Ch obtained by the above procedure to the grip determination device 8.

[0043] Returning to FIG. 2, the second proximity sensor 5 includes a second electrode unit 50 provided on the rim portion 20 and a second detection circuit 52 electrically connected to the second electrode unit 50. The second electrode unit 50 is arc-shaped and extends along the rim portion 20, and is conductive. The second electrode unit 50 is provided inside the rim portion 20. The second electrode unit 50 is arranged within an approximately 90° range between 225° and 315° of the rim portion 20 (i.e., a range that the driver can hold primarily with their left hand). Note that, hereinafter, the arrangement position of the second electrode unit 50 on the rim portion 20 is also referred to as the left rim portion 20L. The second detection circuit 52 is connected to the second electrode unit 50 via wiring 51. The second detection circuit 52 detects the capacitance between the second electrode unit 50 and ground as a value that increases or decreases depending on the distance between the arrangement position of the second electrode unit 50 and the human body. The closer the position of the second electrode unit 50 is to the human body, the greater the capacitance between the second electrode unit 50 and the ground. The capacitance detection value Ch_2 by the second detection circuit 52 is transmitted to the grip determination device 8. Note that the circuit configuration of the second detection circuit 52 is almost the same as that of the first detection circuit 42 shown in FIG. 2, so a detailed description thereof will be omitted.

[0044] The third proximity sensor 6 includes a third electrode 60 provided on the rim 20 and a third detection circuit 62 electrically connected to the third electrode 60. The third electrode 60 is arc-shaped and extends along the rim 20, and is electrically conductive. The third electrode 60 is provided inside the rim 20. The third electrode 60 is positioned within the rim 20 in a range of approximately 90° between 315° and 405° (45°) (i.e., a range that the driver can hold with their right or left hand). Hereinafter, the position of the third electrode 60 on the rim 20 is also referred to as the upper rim portion 20U. The third detection circuit 62 is connected to the third electrode 60 via wiring 61. The third detection circuit 62 detects the capacitance between the third electrode 60 and ground as a value that increases or decreases depending on the distance between the position of the third electrode 60 and the human body. The closer the position of the third electrode unit 60 is to the human body, the greater the capacitance between the third electrode unit 60 and the ground. The capacitance detection value Ch_3 by the third detection circuit 62 is transmitted to the grip determination device 8. Note that the circuit configuration of the third detection circuit 62 is almost the same as that of the first detection circuit 42 shown in FIG. 2, so a detailed description thereof will be omitted.

[0045] The fourth proximity sensor 7 includes a fourth electrode 70 provided on the rim 20 and a fourth detection circuit 72 electrically connected to the fourth electrode 70. The fourth electrode 70 is arc-shaped and extends along the rim 20, and is conductive. The fourth electrode 70 is provided inside the rim 20. The fourth electrode 70 is located within an approximately 90° range between 135° and 225° of the rim 20 (i.e., a range that can be held by the driver with either the right or left hand and that is closest to the driver's knees). Note that hereinafter, the location of the fourth electrode 70 on the rim 20 is also referred to as the lower rim portion 20D. The fourth detection circuit 72 is connected to the fourth electrode 70 via wiring 71. The fourth detection circuit 72 detects the capacitance between the fourth electrode 70 and ground as a value that increases or decreases depending on the distance between the location of the fourth electrode 70 and the human body. The closer the position of the fourth electrode unit 70 is to the human body, the greater the capacitance between the fourth electrode unit 70 and the ground. The capacitance detection value Ch_4 by the fourth detection circuit 72 is transmitted to the grip determination device 8. Note that the circuit configuration of the fourth detection circuit 72 is almost the same as that of the first detection circuit 42 shown in FIG. 2, so a detailed description thereof will be omitted.

[0046] The grip determination device 8 determines whether the driver is gripping the rim portion 20, i.e., whether the driver is gripping the rim portion 20, based on the detection values ​​Ch_1, Ch_2, Ch_3, and Ch_4 of the four proximity sensors 4 to 7, each arranged at a different position on the rim portion 20 as described above.

[0047] The grip determination device 8 includes a selection unit 81 that selects a target sensor from the four proximity sensors 4, 5, 6, 7 based on the degree of change in the detection values ​​Ch_1, Ch_2, Ch_3, Ch_4 of the four proximity sensors 4, 5, 6, 7 over a predetermined period of time, and a determination unit 82 that determines whether the driver is gripping the rim portion 20 based on the detection value of the target sensor selected by the selection unit 81.

[0048] Fig. 3 is a flowchart showing the procedure for determining whether or not the driver is gripping the rim portion based on the detection values ​​Ch_1 to Ch_4 in the grip determination device 8. The process shown in Fig. 3 is repeatedly executed in the grip determination device 8 under a predetermined control cycle in response to the driver operating a start switch (not shown) to start the vehicle.

[0049] First, in step ST1, the selection unit 81 and the determination unit 82 acquire the detection values ​​Ch_1 to Ch_4 of the proximity sensors 4 to 7, and then the process proceeds to step ST2.

[0050] Next, in step ST2, the determination unit 82 determines whether the value of the grip flag Fg is 1. The grip flag Fg is a flag that indicates that the driver is gripping the rim portion 20 with his / her hands, and is set to a value of 0 in step ST17 or ST24 described below, and is set to a value of 1 in step ST16 or ST23 described below.

[0051] If the determination result of step ST2 is NO, i.e., if the determination unit 82 determines that the rim portion 20 was not grasped in the previous control cycle, the process proceeds to step ST3. In step ST3, the determination unit 82 executes a first grip determination process shown in FIG. 4, which will be described later, and then ends the process shown in FIG. 3. If the determination result of step ST2 is YES, i.e., if the determination unit 82 determines that the rim portion 20 was grasped in the previous control cycle, the process proceeds to step ST4. In step ST4, the determination unit 82 executes a second grip determination process shown in FIG. 5, which will be described later, and then ends the process shown in FIG. 3.

[0052] FIG. 4 is a flowchart showing a specific procedure of the first grip determination process. First, in step ST11, the selection unit 81 calculates the degrees of change ΔCh_1, ΔCh_2, ΔCh_3, and ΔCh_4 of the detection values ​​Ch_1, Ch_2, Ch_3, and Ch_4 of each of the proximity sensors 4-7 over a predetermined time period, and then proceeds to step ST12. More specifically, the selection unit 81 calculates the degrees of change ΔCh_1 to ΔCh_4 of each of the proximity sensors 4-7 by subtracting the detection values ​​Ch_1 to Ch_4 of each of the proximity sensors 4-7 acquired in the control cycle n cycles ago (n is an integer equal to or greater than 1) from the detection values ​​Ch_1 to Ch_4 of each of the proximity sensors 4-7 acquired in the current control cycle. Therefore, the degrees of change ΔCh_1 to ΔCh_4 calculated in step ST11 correspond to the amount of approach, i.e., the approach speed, of a part of the driver's body to the arrangement positions of the electrode units 40-70 over a predetermined time period.

[0053] In step ST12, the selection unit 81 selects a target sensor from among the plurality of proximity sensors 4 to 7 based on the degrees of change ΔCh_1 to ΔCh_4 of each of the proximity sensors 4 to 7 calculated in step ST11, and proceeds to step ST13. More specifically, the selection unit 81 selects, as the target sensor, one of the plurality of proximity sensors 4 to 7 whose detection value has a large degree of change. Two examples of specific procedures for the selection unit 81 to select a target sensor from among the plurality of proximity sensors will now be described.

[0054] In the first example, the selector 81 selects a target sensor by comparing the magnitudes of the degrees of change ΔCh_1 to ΔCh_4 of the detection values ​​of the multiple proximity sensors 4 to 7. More specifically, the selector 81 selects M (M is an integer greater than or equal to 1 and less than N) target sensors from all N (N is an integer greater than or equal to 2, and is 4 in this embodiment) proximity sensors 4 to 7 in descending order of the degrees of change ΔCh_1 to ΔCh_4. Therefore, in the first example, M target sensors are selected from the multiple proximity sensors 4 to 7 in descending order of the approach speed of a part of the driver's body to the arrangement positions of the electrode units 40 to 70.

[0055] In the second example, the selector 81 selects a target sensor by comparing the degrees of change ΔCh_1 to ΔCh_4 of the detection values ​​of the multiple proximity sensors 4 to 7 with a predetermined selection threshold. More specifically, the selector 81 selects, from the multiple proximity sensors 4 to 7, those sensors whose degrees of change ΔCh_1 to ΔCh_4 are greater than the selection threshold. This selection threshold is a threshold determined for the degree of change in the detection values ​​of the proximity sensors 4 to 7 corresponding to the approach speed of a part of the driver's body to the positions of the electrode units 40 to 70, as described above. Therefore, in the second example, from the multiple proximity sensors 4 to 7, those sensors whose approach speed of a part of the driver's body to the positions of the electrode units 40 to 70 is faster than the speed corresponding to the selection threshold are selected as the target sensors.

[0056] In step ST13, the determination unit 82 determines whether or not at least one of the plurality of proximity sensors 4 to 7 has been selected as the target sensor in step ST12. If the determination result in step ST13 is YES, the determination unit 82 proceeds to step ST14, and if the determination result is NO, the determination unit 82 proceeds to step ST17.

[0057] In step ST14, the determination unit 82 calculates the sum of the detection values ​​of the proximity sensors selected as target sensors from among the multiple proximity sensors, and proceeds to step ST15. In step ST15, the determination unit 82 determines whether the sum of the detection values ​​of the target sensors calculated in step ST14 (i.e., the detection value of the target sensor if there is only one target sensor) is equal to or greater than a predetermined first grip threshold. This first grip threshold is a threshold set for the detection value of the proximity sensors 4 to 7, i.e., for the capacitance corresponding to the proximity of a part of the driver's body to the arrangement position of each of the electrode units 40 to 70.

[0058] If the determination result of step ST15 is YES, the determination unit 82 proceeds to step ST16. In step ST16, the determination unit 82 determines that the rim portion 20 is being gripped by the driver, and ends the processing of Fig. 4. More specifically, in step ST16, the determination unit 82 sets the value of the grip flag Fg to "1", and ends the processing of Fig. 4.

[0059] Furthermore, if the determination result in step ST15 is NO, or if the determination result in step ST13 is NO, the determination unit 82 proceeds to step ST17. In step ST17, the determination unit 82 determines that the rim portion 20 is not being gripped by the driver, and ends the processing in Fig. 4. More specifically, in step ST17, the determination unit 82 ends the processing in Fig. 4 while maintaining the value of the grip flag Fg at "0".

[0060] As described above, while the determination unit 82 determines that the rim portion 20 is not being grasped (i.e., while the value of the gripping flag Fg is set to "0"), the selection unit 81 repeatedly executes a selection process (steps ST11 to ST12 in FIG. 4) for selecting a target sensor from the multiple proximity sensors 4 to 7 in a predetermined control cycle. Furthermore, if the determination unit 82 determines that the rim portion 20 is not being grasped in the previous control cycle (i.e., when the value of the gripping flag Fg is set to "0"), it determines whether or not the rim portion 20 is being grasped based on the detection values ​​of only the proximity sensors 4 to 7 selected as the target sensors by the selection process.

[0061] FIG. 5 is a flowchart showing a specific procedure of the second grip determination process. First, in step ST21, the determination unit 82 calculates the sum of the detection values ​​Ch_1 to Ch_4 of the multiple proximity sensors 4 to 7, more specifically, all of the proximity sensors 4 to 7 provided on the rim portion 20, and then proceeds to step ST22. In step ST22, the determination unit 82 determines whether the sum calculated in step ST21 is equal to or greater than a second grip threshold. This second grip threshold, like the above-mentioned first grip threshold, is a threshold set for the detection values ​​of the proximity sensors 4 to 7, i.e., for the capacitance corresponding to the proximity of parts of the driver's body to the arrangement positions of the electrode units 40 to 70.

[0062] If the determination result of step ST22 is YES, the determination unit 82 proceeds to step ST23. In step ST23, the determination unit 82 determines that the rim portion 20 is being gripped by the driver, and ends the processing of Fig. 5. More specifically, in step ST23, the determination unit 82 ends the processing of Fig. 5 while maintaining the value of the grip flag Fg at "1".

[0063] Furthermore, if the determination result of step ST22 is NO, the determination unit 82 proceeds to step ST24. In step ST24, the determination unit 82 determines that the rim portion 20 is not being gripped by the driver, and ends the processing of Fig. 5. More specifically, in step ST24, the determination unit 82 sets the value of the grip flag Fg to "0", and ends the processing of Fig. 5.

[0064] As described above, when the selection unit 81 determines that the rim portion 20 is being grasped in the previous control cycle (i.e., when the value of the grasping flag Fg is set to "1"), it determines whether the rim portion 20 is being grasped or not based on the detection values ​​of the multiple proximity sensors 4-7, more specifically, all of the proximity sensors 4-7 provided on the rim portion 20.

[0065] The steering device 1 according to this embodiment provides the following effects. (1) In the steering device 1, multiple proximity sensors 4-7 are provided on the rim portion 20 of the steering wheel 2 that can be gripped by the driver. Here, if the driver's physique is larger than average, parts of the driver's body, such as the abdomen or knees, sitting in the driver's seat will approach the lower rim portion 20D. For this reason, the detection value Ch_4 of the fourth proximity sensor 7 arranged near the lower rim portion 20D is constantly larger than average, but does not change significantly while driving. In contrast, the detection value of the proximity sensor arranged near the part that the driver grips with his or her hand changes significantly each time the driver grips the steering wheel. Therefore, the selection unit 81 of the grip determination device 8 selects a target sensor from the multiple proximity sensors 4-7 based on the degree of change ΔCh_1-ΔCh_4 in the detection values ​​Ch_1-Ch_4 of the multiple proximity sensors 4-7, and the determination unit 82 of the grip determination device 8 determines whether or not the driver is gripping the steering wheel based on the detection value of the selected target sensor. According to the steering device 1, it is possible to exclude from the target sensors, among the multiple proximity sensors 4 to 7, those whose detection values ​​are large due to the driver's physique, so that it is possible to appropriately determine whether the rim portion 20 is being gripped regardless of the driver's physique, thereby improving traffic safety.

[0066] (2) The selection unit 81 selects a target sensor from the plurality of proximity sensors 4 to 7 by comparing the magnitudes of the change degrees ΔCh_1 to ΔCh_4 of the detection values ​​Ch_1 to Ch_4 of the plurality of proximity sensors 4 to 7 with each other, and can select as the target sensor from the plurality of proximity sensors 4 to 7 one that is located near the point where the driver holds it with his hand.

[0067] (3) The selection unit 81 can select M of the N proximity sensors 4 to 7 as target sensors in descending order of the degree of change, thereby selecting from the multiple proximity sensors 4 to 7 the one that is located near the point where the driver holds it with his hand as the target sensor.

[0068] (4) The selection unit 81 selects a target sensor from the plurality of proximity sensors 4 to 7 by comparing the degree of change ΔCh_1 to ΔCh_4 of the detection values ​​Ch_1 to Ch_4 of the plurality of proximity sensors 4 to 7 with a selection threshold, which is a threshold value set for this degree of change, and can select as the target sensor from the plurality of proximity sensors 4 to 7 one that is located near the point where the driver holds it with his hand.

[0069] (5) The selection unit 81 can select as the target sensor from among the multiple proximity sensors 4 to 7 those whose change degrees ΔCh_1 to ΔCh_4 are greater than the selection threshold, thereby selecting as the target sensor from among the multiple proximity sensors 4 to 7 those that are located near the point where the driver holds them with his hand.

[0070] (6) While the determination unit 82 determines that the rim portion 20 is not being grasped, the selection unit 81 executes a selection process to select a target sensor from the multiple proximity sensors 4 to 7 at a predetermined control period, thereby enabling the selection unit 81 to reselect an appropriate target sensor each time the driver re-grabs the rim portion 20 or changes the gripping location.

[0071] (7) The determination unit 82 determines whether the rim portion 20 is being gripped at each predetermined control cycle, and if it determines that the rim portion 20 was not being gripped during the previous control cycle, it can accurately determine whether the rim portion 20 is being gripped by the driver by determining whether the rim portion 20 is being gripped based on the detection values ​​of only the sensors selected as target sensors by the selection unit 81. Furthermore, if it determines that the rim portion 20 was being gripped during the previous control cycle, the determination unit 82 determines whether the rim portion 20 is being gripped based on the detection values ​​of all of the proximity sensors 4 to 7 provided on the rim portion 20, thereby making it possible to appropriately determine whether the rim portion 20 is being gripped even if, for example, the driver slides the gripped portion while gripping the rim portion 20.

[0072] (8) When the detection value of the target sensor is equal to or greater than the first gripping threshold, which is a threshold value set for this detection value, the judgment unit 82 judges that the rim portion 20 is being gripped, thereby enabling accurate determination that the driver is gripping the vicinity of the position where the target sensor is located.

[0073] (9) The determination unit 82 determines that the rim portion 20 is being gripped when the sum of the detection values ​​of the multiple target sensors is equal to or greater than the first grip threshold or the second grip threshold, which are thresholds determined for these detection values. This makes it possible to accurately determine whether the rim portion 20 is being gripped even when, for example, the driver is gripping the rim portion across the locations where multiple proximity sensors 4 to 7 are located.

[0074] 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.

[0075] For example, in the above embodiment, four proximity sensors 4 to 7 are arranged on the rim portion 20, but the number of proximity sensors arranged on the rim portion 20 is not limited to this. The present invention is applicable as long as two or more proximity sensors are arranged on the rim portion 20. [Explanation of symbols]

[0076] 1...Steering device 2...Steering wheel 20...Rim part (gripping part) 3...Steering shaft 4...1st proximity sensor (proximity sensor) 40...First electrode part 42...First detection circuit 5...Second proximity sensor (proximity sensor) 50…Second electrode part 52...Second detection circuit 6...Third proximity sensor (proximity sensor) 60…Third electrode part 62...Third detection circuit 7...Fourth proximity sensor (proximity sensor) 70…Fourth electrode part 72...Fourth detection circuit 8…Control and determination device 81…Choose the first part 82… Judgment Department

Claims

1. a steering wheel that accepts steering operations of the vehicle by a driver; a plurality of proximity sensors that are arranged in a grip portion of the steering wheel that can be gripped by a driver and output detection values ​​that increase or decrease depending on the distance between each of the sensors' positions and the driver's body; a grip determination device that determines whether or not the grip portion is being gripped based on a detection value of the proximity sensor, The grip determination device includes: a selection unit that selects a target sensor from the plurality of proximity sensors based on a degree of change in the detection values ​​of the plurality of proximity sensors; a determination unit that determines whether the grip unit is gripping the object based on the detection value of the target sensor, The steering device is characterized in that the selection unit selects the target sensor by comparing the magnitudes of the degrees of change in the detection values ​​of the plurality of proximity sensors with each other.

2. 2. The steering device according to claim 1, wherein the selection unit selects M (M is an integer greater than or equal to 1 and less than N) of the proximity sensors as the target sensors in descending order of the degree of change from the proximity sensors with the greatest degree of change (N is an integer greater than or equal to 2).

3. 2. The steering device according to claim 1, wherein the determination unit determines that the grip portion is being gripped when the detection value of the target sensor is equal to or greater than a grip threshold that is a threshold value set for the detection value.

4. A steering wheel that accepts steering operations of a vehicle by a driver; a plurality of proximity sensors that are arranged in a grip portion of the steering wheel that can be gripped by a driver and output detection values ​​that increase or decrease depending on the distance between each of the sensors' positions and the driver's body; a grip determination device that determines whether or not the grip portion is being gripped based on a detection value of the proximity sensor, The grip determination device includes: a selection unit that selects a target sensor from the plurality of proximity sensors based on a degree of change in the detection values ​​of the plurality of proximity sensors; a determination unit that determines whether the grip unit is gripping the object based on the detection value of the target sensor, The determination unit determines whether the gripping unit is gripping or not at predetermined intervals, and If it is determined that the gripping portion is not gripped in the previous cycle, it determines whether the gripping portion is gripped or not based on detection values ​​of only the proximity sensors selected as the target sensors among the plurality of proximity sensors; A steering device characterized in that, when it is determined that the grip portion is gripped in the previous cycle, it is determined whether the grip portion is gripped or not based on detection values ​​of the plurality of proximity sensors.

5. A steering wheel that accepts steering operations of a vehicle by a driver; a plurality of proximity sensors that are arranged in a grip portion of the steering wheel that can be gripped by a driver and output detection values ​​that increase or decrease depending on the distance between each of the sensors' positions and the driver's body; a grip determination device that determines whether or not the grip portion is being gripped based on a detection value of the proximity sensor, The grip determination device includes: a selection unit that selects a target sensor from the plurality of proximity sensors based on a degree of change in the detection values ​​of the plurality of proximity sensors; a determination unit that determines whether the grip unit is gripping the object based on the detection value of the target sensor, The steering device is characterized in that the determination unit determines that the grip portion is being gripped when the sum of the detection values ​​of the multiple target sensors is equal to or greater than a grip threshold, which is a threshold value set for the detection values.

6. 6. The steering device according to claim 4, wherein the selection unit selects the target sensor by comparing the degree of change in the detection values ​​of the plurality of proximity sensors with a selection threshold that is a threshold value set for the degree of change.

7. The steering device according to claim 6, wherein the selector selects, as the target sensor, one of the plurality of proximity sensors whose degree of change is greater than the selection threshold value.

8. 8. The steering device according to claim 4, wherein the selection unit executes a selection process for selecting the target sensor from the plurality of proximity sensors at a predetermined cycle while the determination unit determines that the gripping portion is not being gripped.

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