Steering device

Abstract

To appropriately detect gripping of a steering handle.SOLUTION: A steering device includes a steering handle, and a sensor unit for detecting contact / approach of a human body with / to the steering handle, wherein the sensor unit includes a plurality of electrodes 60R1 to 60R4 provided on the steering handle, and a plurality of electrodes 60R1d to 60R4d for correction arranged on the surfaces of the electrodes 60R1 to 60R4 so as to correct a capacitance value based on the electrodes 60R1 to 60R4.SELECTED DRAWING: Figure 4B

Description

[Technical Field]

[0001] The present invention relates to a steering device that detects whether it is being gripped by an occupant. [Background technology]

[0002] In a device that uses a capacitive touch sensor to determine whether or not a touch has occurred, a technique is known in which a capacitive dummy sensor is provided near the touch sensor (see, for example, Patent Document 1). By determining whether or not a touch has occurred based on the detection values ​​of the touch sensor and the dummy sensor, false detections due to unintentional contact and external radio wave noise can be prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-53123 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional technologies are prone to false detection due to differences in the installation environment between the touch sensor and the dummy sensor. For example, capacitance may fluctuate depending on temperature, which can be particularly problematic in a vehicle environment where temperature changes are likely to occur. The present invention reduces the influence of differences in the installation environment between touch sensors and dummy sensors and appropriately detects the driver's grip on the steering wheel, leading to improved traffic safety and contributing to the development of sustainable transportation systems. [Means for solving the problem]

[0005] One aspect of the present invention is a steering device including a steering wheel and a sensor unit that detects contact or proximity of a human body with the steering wheel, the sensor unit including a plurality of electrodes provided on the steering wheel and a plurality of correction electrodes arranged on the surfaces of the electrodes for correcting capacitance values ​​based on the electrodes. The correction electrodes are arranged in the longitudinal direction along the surface of the electrode. [Effects of the Invention]

[0006] According to the present invention, it is possible to appropriately detect whether the steering wheel is being gripped. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating the configuration of a steering device and a safe driving support system including the steering device according to an embodiment of the invention; [Figure 2] FIG. 4 is a schematic diagram illustrating a grip detection range by an electrode. [Figure 3] FIG. 2 is a diagram illustrating an example of a circuit configuration of a sensor unit. [Figure 4A] Schematic diagram of the electrode on the right side of Figure 1. [Figure 4B] Schematic diagram of the electrode in Figure 4A unfolded. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. <System configuration> FIG. 1 is a diagram illustrating the configuration of a steering device 1 according to an embodiment and a safe driving support system 9 including the steering device 1. As shown in FIG.

[0009] 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.

[0010] In the embodiment, each of the devices 81 to 84 constituting the control device group 8 is described as an in-vehicle device capable of communicating with the steering device 1, for example, by CAN communication via a CAN (Controller Area Network) bus 80, but all or some of the multiple devices 81 to 84 constituting the control device group 8 may be configured as an off-vehicle device capable of wireless communication with the steering device 1 via an in-vehicle communication device not shown.

[0011] <Outline of the steering system> The steering device 1 includes a steering wheel 2 that accepts the driver's steering operation of the vehicle and auxiliary operation of vehicle auxiliary equipment, a steering shaft 3 that supports the steering wheel 2, and a grip detection device 6 that detects the driver's grip on the steering wheel 2. The auxiliary operation includes operations for a navigation system, an audio system, an air conditioning system, a multi-information display, etc., as well as operations for a driving assistance system. The driving assistance system includes, for example, a Lane Keep Assist System (LKAS) and an Adaptive Cruise Control (ACC).

[0012] The steering wheel 2 comprises a rim portion 20, which is, for example, annular and 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 periphery 21 of the rim portion 20.

[0013] The hub portion 23 is disk-shaped and is provided, for example, at the center of the rim portion 20 as viewed from the driver's seat, 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 viewed from the driver's seat. The steering shaft 3 is an axial connecting member that connects a core metal that is the framework 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 by this steering shaft 3.

[0014] 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 viewed from the driver's seat to left spoke connection portion 26L, which is the left portion of the rim inner periphery 21 as viewed from the driver's seat. The right spoke 25R extends horizontally and parallel to the left spoke 25L and connects the right portion of the hub portion 23 as viewed from the driver's seat to right spoke connection portion 26R, which is the right portion of the rim inner periphery 21 as viewed from the driver's seat. 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 viewed from the driver's seat to the lower portion of the rim inner periphery 21 as viewed from the driver's seat.

[0015] 1, a left thumb locking portion 27L that is concave radially outward when viewed from the driver's seat is formed at the part of rim inner circumferential portion 21 that connects to the upper part of left spoke connection portion 26L when viewed from the front from the driver's seat. Also, a right thumb locking portion 27R that is concave radially outward when viewed from the front from the driver's seat is formed at the part of rim inner circumferential portion 21 that connects to the upper part of right spoke connection portion 26R when viewed from the front from the driver's seat.

[0016] In the steering device 1 according to the 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, 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.

[0017] Furthermore, in the steering device 1 according to the 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, the base of the thumb is in contact with the right spoke connection portion 26R, and the remaining fingers of the right hand grip the rim portion 20. 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.

[0018] 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 accept operation commands for the driver to operate vehicle accessories (not shown). The left accessory operation console unit 5L and the right accessory operation console unit 5R each have a substantially rectangular shape when viewed from the driver. The driver can operate the vehicle accessories by operating multiple switches provided on the left accessory operation console unit 5L and the right accessory operation console unit 5R with their fingers. The left accessory operation console unit 5L and the right accessory operation console unit 5R may also be called the left function switch unit and the right function switch unit, respectively.

[0019] In the following description, 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, and the orientations of each spoke portion 25L, 25R, and 25D may also be expressed in degrees clockwise around the steering shaft 3 and based on the position of the top end 20C of the rim portion 20 as viewed from the front from the driver's seat. That is, the right spoke portion 25R extends along an angle of 90 degrees, connecting the hub portion 23 and the 90-degree portion of the rim inner periphery 21. The lower spoke portion 25D extends along an angle of 180 degrees, connecting the hub portion 23 and the 180-degree portion of the rim inner periphery 21. The left spoke portion 25L extends along an angle of 270 degrees, connecting the hub portion 23 and the 270-degree portion of the rim inner periphery 21. Expressed in terms of the clockwise angle [deg], the recommended grip position for the driver's left hand is set to a position of 270 deg on the rim portion 20. The recommended grip position for the driver's right hand is set to a position of 90 deg on the rim portion 20.

[0020] <Grip detection device> As an example, the grip detection device 6 includes an electrode 60 provided on the steering wheel 2 and a sensor unit 62 electrically connected to the electrode 60. Hereinafter, the eight electrodes, namely, the first left electrode 60L1, the second left electrode 60L2, the third left electrode 60L3, the fourth left electrode 60L4, and the first right electrode 60R1, the second right electrode 60R2, the third right electrode 60R3, and the fourth right electrode 60R4, may be collectively referred to as electrodes 60.

[0021] Each of the eight electrodes constituting the electrode 60 is formed in the shape of a conductive plate. The first left electrode 60L1, the second left electrode 60L2, the third left electrode 60L3, and the fourth left electrode 60L4 are provided on the steering wheel 2 near a recommended gripping position with the left hand that is determined with respect to the rim portion 20. More specifically, the first left electrode 60L1 and the second left electrode 60L2 are provided on the left spoke portion 25L, as viewed from the driver, along an upper and radially outer side wall surface of the left accessory operation console unit 5L (more specifically, along an end surface of a printed wiring board (which may also be called an electronic board) (not shown) that is arranged within the left accessory operation console unit 5L). In addition, the third left electrode 60L3 and the fourth left electrode 60L4 are each provided below the left accessory operation console unit 5L (more specifically, on the end surface of the printed wiring board) in the left spoke portion 25L when viewed from the driver, and along the surface facing the rim portion 20 in the lower left part of the hub portion 23.

[0022] Similarly, the first right electrode 60R1, the second right electrode 60R2, the third right electrode 60R3, and the fourth right electrode 60R4 are provided on the steering wheel 2 near recommended gripping positions for the right hand that are determined with respect to the rim portion 20. More specifically, the first right electrode 60R1 and the second right electrode 60R2 are each provided on the right spoke portion 25R as viewed from the driver, along the upper and radially outer side wall surfaces of the right accessory operation console unit 5R (more specifically, along the end surfaces of the printed wiring board arranged in the right accessory operation console unit 5R). In addition, the third right electrode 60R3 and the fourth right electrode 60R4 are each provided below the right accessory operation console unit 5R (more specifically, on the end surface of the printed wiring board) in the right spoke portion 25R as viewed by the driver, and along the surface facing the rim portion 20 in the lower right part of the hub portion 23. Of the eight electrodes, the first left electrode 60L1, the second left electrode 60L2, the third left electrode 60L3, and the fourth left electrode 60L4 may be integrally formed on the base substrate while being insulated from each other. Similarly, the first right electrode 60R1, the second right electrode 60R2, the third right electrode 60R3, and the fourth right electrode 60R4 may be integrally formed on the base substrate while being insulated from each other.

[0023] <Sensor unit> The sensor unit 62 includes eight sensor units 62L1, 62L2, 62L3, 62L4, 62R1, 62R2, 62R3, and 62R4 corresponding to the eight electrodes 60L1, 60L2, 60L3, 60L4, 60R1, 60R2, 60R3, and 60R4. The sensor unit 62L1 is connected to the first left electrode 60L1 via a left wiring 61L1. The sensor unit 62L2 is connected to the second left electrode 60L2 via a left wiring 61L2. The sensor unit 62L3 is connected to the third left electrode 60L3 via a left wiring 61L3. The sensor unit 62L4 is connected to the fourth left electrode 60L4 via a left wiring 61L4.

[0024] Additionally, the sensor unit 62R1 is connected to the first right electrode 60R1 via the right wiring 61R1. The sensor unit 62R2 is connected to the second right electrode 60R2 via the right wiring 61R2. The sensor unit 62R3 is connected to the third right electrode 60R3 via the right wiring 61R3. The sensor unit 62R4 is connected to the fourth right electrode 60R4 via the right wiring 61R4. The sensor units 62L1 to 62L4 are provided, for example, inside the left spoke portion 25L together with the above-mentioned left accessory operation console unit 5L. The sensor units 62R1 to 62R4 are provided inside the right spoke portion 25R together with the above-mentioned right accessory operation console unit 5R.

[0025] <Grip detection range> 2 is a schematic diagram illustrating grip detection ranges RL1-RL4 and RR1-RR4 defined by the electrodes 60 (60L1-60L4 and 60R1-60R4) described above. By applying a predetermined voltage to the corresponding electrodes 60 (60L1-60L4 and 60R1-60R4), electric field lines are induced in the grip detection ranges RL1-RL4 and RR1-RR4 from the electrodes 60 (60L1-60L4 and 60R1-60R4).

[0026] In this embodiment, as described above, the first left electrode 60L1 and the second left electrode 60L2 are provided on the left spoke portion 25L near the recommended gripping position (270 degrees) of the rim portion 20 for the left hand, and the third left electrode 60L3 and the fourth left electrode 60L4 are provided on the hub portion 23 near the recommended gripping position (270 to 180 degrees) of the rim portion 20 for the left hand. By configuring it in this manner, the grip detection ranges RL1 and RL2 (330° to 260°) correspond to the first left electrode 60L1 and the second left electrode 60L2, and the grip detection ranges RL3 and RL4 (260° to 210°) correspond to the third left electrode 60L3 and the fourth left electrode 60L4.

[0027] Similarly, the first right electrode 60R1 and the second right electrode 60R2 are provided on the right spoke portion 25R near the recommended gripping position (90 degrees) of the rim portion 20 for the right hand, and the third right electrode 60R3 and the fourth right electrode 60R4 are provided on the hub portion 23 near the recommended gripping position (90 to 180 degrees) of the rim portion 20 for the right hand. By configuring it in this manner, the grip detection ranges RR1 and RR2 (30° to 100°) correspond to the first right electrode 60R1 and the second right electrode 60R2, and the grip detection ranges RR3 and RR4 (100° to 150°) correspond to the third right electrode 60R3 and the fourth right electrode 60R4.

[0028] <Circuit configuration example> 3 is a diagram illustrating an example of the circuit configuration of sensor unit 62R1 of grip detection device 6. Although not shown, the circuit configurations of the other sensor units 62L1 to 62L4 and 62R2 to 62R4 other than sensor unit 62R1 are similar. The sensor unit 62R1 measures the electrical characteristics of the first right electrode 60R1 (e.g., the capacitance between the first right electrode 60R1 and ground (e.g., the vehicle body)), 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.

[0029] The sensor unit 62R1 includes a first switch SW1, a pulse power supply 63, an amplifier 64, a control unit 67, a second switch SW2, a charging capacitor 65, a measuring unit 68, and a detection unit 69, and uses these to detect the driver's grip on the steering wheel 2. In Figure 3, the capacitance between the first right electrode 60R1 and ground is shown divided into a capacitance Ch formed by the human body H, including the driver's hands operating the steering wheel 2, and a floating capacitance Ce formed by floating capacitors E, such as wiring and components, excluding the human body H.

[0030] As shown in Fig. 3, the pulse power supply 63 and the amplifier 64 are connected in series. Furthermore, the second switch SW2 and the charging capacitor 65 are connected in parallel. The series circuit consisting of the pulse power supply 63 and the amplifier 64 and the parallel circuit consisting of the second switch SW2 and the charging capacitor 65 are connected via the first switch SW1. More specifically, the output terminal of the amplifier 64 and the first right electrode 60R1 are connected via the first switch SW1 and the right wiring 61R1. Furthermore, the second switch SW2 and the charging capacitor 65 are connected to the first right electrode 60R1 via the first switch SW1 and the right wiring 61R1.

[0031] The pulsed power supply 63 supplies a pulsed voltage Vs of a predetermined frequency and a predetermined voltage to the amplifier 64 in response to, for example, a command from the control unit 67. The amplifier 64 amplifies the pulsed voltage Vs supplied from the pulsed power supply 63 and applies it to the first right electrode 60R1 via the first switch SW1 and the right wiring 61R1.

[0032] The second switch SW2 is a switching element such as a transistor that is turned on / off by, for example, a drive circuit (not shown) in the control unit 67. For example, the control unit 67 turns off the second switch SW2 to accumulate (or charge) the charge capacitor 65 until the voltage VCref of the charge capacitor 65 reaches a predetermined voltage threshold Vthr. After the voltage VCref reaches the threshold Vthr, the control unit 67 further turns on the second switch SW2 to discharge the charge accumulated in the charge capacitor 65.

[0033] The first switch SW1 is a switching element that is switched by, for example, a drive circuit (not shown) in the control unit 67, and is configured by, for example, a field effect transistor (FET). In this embodiment, the first switch SW1 has a terminal t1 for connecting the first right electrode 60R1 and the charging capacitor 65, a terminal t2 for connecting the first right electrode 60R1 and the amplifier 64, and a terminal t3 for connecting the first right electrode 60R1 and the ground line.

[0034] The ground line is at the same potential as the GND pattern of the PCB (Printed Circuit Board) on which the circuits of the sensor unit 62R1 except for the first right electrode 60R1 are formed, and is provided substantially parallel to at least one of the wiring patterns to the terminal t1 and the wiring patterns to the terminal t2. In Fig. 3, the ground line is illustrated parallel to the wiring pattern to the terminal t2. By placing the ground line (GND pattern) near the signal line (wiring pattern to terminal t2), the electromagnetic coupling between the signal line and the ground line is strengthened, making it possible to suppress coupling between the signal line and other patterns on the PCB. In other words, this prevents signals from other patterns on the PCB from being transmitted as noise to the signal line due to leakage currents and the like that flow along the PCB surface, and conversely, prevents signals from the signal line from being transmitted as noise to other patterns on the PCB.

[0035] In response to a command from the control unit 67, the first switch SW1 selects the terminal t1 of the first switch SW1 in response to the rising edge of the pulse voltage Vs of the pulsed power supply 63. As a result, the first right electrode 60R1 and the amplifier 64 are connected via the first switch SW1 and the right wiring 61R1, the pulse voltage supplied from the pulsed power supply 63 and the amplifier 64 is applied to the first right electrode 60R1, and the human body H and the floating capacitor E are charged.

[0036] Next, in response to a command from the control unit 67, the first switch SW1 selects the terminal t2 of the first switch SW1 in response to the falling edge of the pulse voltage Vs of the pulsed power supply 63. As a result, the first right electrode 60R1 and the charging capacitor 65 are connected via the first switch SW1 and the right wiring 61R1, and the charges stored in the human body H and the floating capacitor E are transferred to the charging capacitor 65, thereby charging the charging capacitor 65. As a result, the voltage VCref of the charging capacitor 65 rises.

[0037] In this way, when a pulse voltage is repeatedly applied to the first right electrode 60R1 by the pulse power supply 63 and the amplifier 64, the human body H and the floating capacitor E are alternately charged and discharged, and the voltage VCref of the charging capacitor 65 gradually increases. At this time, the time (which may be expressed as the number of pulses of the pulse power supply 63) until the voltage VCref of the charging capacitor 65 reaches a predetermined voltage threshold Vthr 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 the first right electrode 60R1. That is, when the driver's hand is gripping a portion of the rim portion 20 within the grip detection range RR1 (see FIG. 2) and the capacitance Ch is large, the time it takes for the voltage VCref of the charging capacitor 65 to reach the threshold Vthr is short. On the other hand, when the driver's hand is away from the grip detection range RR1 and the capacitance Ch is small, the time it takes for the voltage VCref of the charging capacitor 65 to reach the voltage threshold Vthr is long.

[0038] Furthermore, the first switch SW1 selects terminal t3 of the first switch SW1 at a predetermined timing in response to a command from the control unit 67. As a result, the first right electrode 60R1 and the ground line are connected via the first switch SW1 and the right wiring 61R1, and the charges stored in the human body H and the floating capacitor E and the charges remaining in the first right electrode 60R1 and the right wiring 61R1 are discharged to the ground line. For example, when selecting terminal t1 of the first switch SW1 described above and when selecting terminal t2 of the first switch SW1, the control unit 67 controls the switching of the first switch SW1 so that terminal t3 is first selected and then terminal t1 and terminal t2 are selected, respectively. In addition, the control unit 67 may control the switching of the first switch SW1 to select terminal t3 of the first switch SW1 in accordance with the timing at which the second switch SW2 is turned on (in other words, the charge stored in the charging capacitor 65 is discharged). Furthermore, the switching of the first switch SW1 may be controlled so as to select the terminal t3 of the first switch SW1 in accordance with the timing at which other accessories operate. The timing at which the terminal t3 of the first switch SW1 is selected can be changed as appropriate by a program executed by the control unit 67.

[0039] The measurement unit 68 measures the time and the number of pulses until the voltage VCref of the charging capacitor 65 reaches the threshold Vthr, and based on the measurement results, indirectly measures the capacitance Ch formed by the human body H present in the vicinity of the first right electrode 60R1. The measurement unit 68 transmits the measurement value Ch_d of the capacitance Ch obtained by the above procedure to the detection unit 69.

[0040] The detection unit 69 detects that the driver is gripping the rim portion 20 based on the capacitance measurement value Ch_d by the measurement unit 68, and when gripping of the rim portion 20 is detected, it estimates the gripping position on the rim portion 20. The detection unit 69 estimates that the larger the value of the capacitance measurement value Ch_d when gripping is detected, the closer the rim portion 20 is to being gripped (for example, 100 deg), and the smaller the value of the capacitance measurement value Ch_d when gripping is detected, the farther the rim portion 20 is to being gripped (for example, 150 deg)

[0041] As described above, the detection section 69 of the sensor unit 62R1 determines the grip detection range of the rim portion 20 based on the measurement value Ch_d of the capacitance Ch formed by the human body H present in the vicinity of the first right electrode 60R1. RR The gripping position of the driver at the rim portion 20 is detected and the gripping position is estimated. Although not explained further, the detection of gripping and estimation of gripping position in gripping detection range RR2 of rim portion 20 by sensor unit 62R2, the detection of gripping and estimation of gripping position in gripping detection range RR3 of rim portion 20 by sensor unit 62R3, and the detection of gripping and estimation of gripping position in gripping detection range RR4 of rim portion 20 by sensor unit 62R4 are similar to the detection of gripping and estimation of gripping position in gripping detection range RR1 of rim portion 20 by sensor unit 62R1 described above. Furthermore, the detection of gripping and estimation of gripping position in the grip detection ranges RL1 to RL4 of the rim portion 20 by the sensor units 62L1 to 62L4 is similar to the detection of gripping and estimation of gripping position in the grip detection range RR1 of the rim portion 20 by the sensor unit 62R1 described above.

[0042] <Capacitance measurement details> The measurement of the capacitance Ch will be described in further detail. The sensor unit 62R1 described above detects the capacitance based on the voltage VCref of the charging capacitor 65, which is charged with electric charges from the human body H and the floating capacitor E. Therefore, the measurement value of the capacitance measured by the sensor unit 62R1 (hereinafter, sometimes referred to as the capacitance value) includes both the capacitance Ch of the human body H and the floating capacitance Ce of the floating capacitor E. The measurement unit 68 performs the following process to exclude the amount equivalent to stray capacitance Ce from the measured capacitance value (in other words, to extract the amount equivalent to capacitance Ch). In the following description, the amount equivalent to stray capacitance Ce will be referred to as the capacitance base value.

[0043] The sensor unit 62R1 is normally controlled to measure the capacitance value n every predetermined time (for example, every 10 msec). The measurement unit 68 calculates the latest capacitance base value n using the following equation (1) based on the capacitance value n measured when the steering wheel 2 is not being gripped by the driver. (Number 1) Capacity base value n = (Capacity value n + WT × Capacity base value (n-1)) / (WT+1)…… (1) Here, the capacitance value n is the capacitance value measured by the sensor unit 62R1. When the steering wheel 2 is not gripped by the driver, the capacitance value n indicates a value equivalent to the stray capacitance Ce. The symbol WT indicates a predetermined weight value. The capacitance base value (n-1) indicates the capacitance base value calculated using equation (1) at the time of the previous calculation (10 msec ago).

[0044] According to the above formula (1), a weighted calculation is performed using the latest capacitance value n and the weighted previous capacitance base value (n-1). Therefore, if the latest capacitance value n changes from the previous value due to a change in the electrode installation environment, it is possible to calculate the latest capacitance base value n so that it does not change significantly from the previous capacitance base value (n-1).

[0045] The measurement unit 68 calculates the latest capacitance difference value n using the following equation (2) every time it measures the capacitance value n and calculates the capacitance base value n at the predetermined time intervals. (Number 2) Capacitance difference value n = capacitance value n - capacitance base value n …… (2) Here, the capacitance value n indicates the most recent capacitance value measured by the sensor unit 62R1, and the capacitance base value n indicates the most recent capacitance base value calculated using the above formula (1).

[0046] If the most recent capacitance difference value n calculated using the above formula (2) is less than a predetermined judgment threshold, the measurement unit 68 determines that the steering wheel 2 is not being held by the driver, and repeats measuring the capacitance value n, calculating the capacitance base value n, and calculating the capacitance difference value n using the above formula (2) at the above predetermined time intervals.

[0047] When the latest capacitance difference value n calculated using the above formula (2) exceeds a predetermined judgment threshold, the measurement unit 68 determines that there is a possibility that the steering wheel 2 is being gripped by the driver and stops calculating the capacitance base value. Then, the measurement of the capacitance value n and the calculation of the capacitance difference value n using the following formula (3) are repeated at the above-mentioned predetermined time intervals. (Number 3) Capacitance difference value n = capacitance value n - capacitance base value p …… (3) Here, the capacitance value n indicates the most recent capacitance value measured by the sensor unit 62R1. When the driver is holding the steering wheel 2, the capacitance value n indicates a value including both the electrostatic capacitance Ch of the human body H and the stray capacitance Ce of the stray capacitor E. The capacitance base value p indicates the past capacitance base value last calculated using the above formula (1).

[0048] When the most recent capacitance difference value n calculated using the above equation (3) becomes less than a predetermined judgment threshold, the measurement unit 68 determines that the steering wheel 2 is not being held by the driver and resumes calculating the capacitance base value n. Then, the measurement of the capacitance value n, the calculation of the capacitance base value n, and the calculation of the capacitance difference value n using the above formula (2) are repeated every predetermined time.

[0049] The measurement unit 68 transmits the capacitance difference value n calculated using the above formula (2) or (3) to the detection unit 69 as a measurement value Ch_d of the capacitance Ch.

[0050] <Measures to prevent fluctuations in measurement values> In the embodiment, for example, in the case of the sensor unit 62R1, the voltage VCref of the charging capacitor 65 fluctuates due to the installation environment (particularly temperature and humidity) of the first right electrode 60R1. Specifically, the voltage VCref of the charging capacitor 65 fluctuates due to changes in the stray capacitance Ce of the floating capacitor E accompanying environmental changes such as temperature. The fluctuation in the voltage VCref also affects the measurement value Ch_d of the capacitance Ch.

[0051] In order to suppress the influence of temperature and the like on the measured value Ch_d of the electrostatic capacitance Ch, the measurement unit 68 corrects the capacitance base value p in the above equation (3) to calculate the capacitance difference value n as follows: FIG. 4A is a schematic diagram illustrating the first right electrode 60R1, the second right electrode 60R2, the third right electrode 60R3, and the fourth right electrode 60R4 out of the eight electrodes 60L1, 60L2, 60L3, 60L4, 60R1, 60R2, 60R3, and 60R4 in FIG. 1.

[0052] The four electrodes 60R1, 60R2, 60R3, and 60R4 are arranged along the upper and radially outer side wall surfaces of the right accessory operation console unit 5R at the right spoke portion 25R as viewed from the driver, and along the surface facing the rim portion 20 below the right accessory operation console unit 5R and at the lower right part of the hub portion 23.

[0053] 4B is a schematic diagram showing the four electrodes 60R1, 60R2, 60R3, and 60R4 shown in FIG. 4A. Conductive linear dummy electrodes 60R1d, 60R2d, 60R3d, and 60R4d are arranged along the surface of each of the conductive plate-like electrodes 60R1, 60R2, 60R3, and 60R4, respectively, while being insulated from the electrodes 60R1, 60R2, 60R3, and 60R4. More specifically, when viewed with the longitudinal direction of each electrode aligned horizontally, the dummy electrodes 60R1d, 60R2d, 60R3d, and 60R4d are arranged in a direction that crosses the surface of each of the electrodes 60R1, 60R2, 60R3, and 60R4.

[0054] Each of the dummy electrodes 60R1d, 60R2d, 60R3d, and 60R4d has a smaller surface area than the corresponding four electrodes 60R1, 60R2, 60R3, and 60R4 (for example, 1 / 100th of each). This makes it difficult to measure the capacitance value based on the charge stored in the human body H using the dummy electrodes. However, it is possible to grasp the tendency of the capacitance value based on the charge stored in the floating capacitor E (corresponding to the above-mentioned capacitance base value n) to fluctuate due to the installation environment of the dummy electrodes.

[0055] For example, the first right electrode 60R1 and the dummy electrode 60R1d corresponding to the first right electrode 60R1 are considered to be in the same installation environment. If the capacitance value equivalent to the stray capacitance Ce measured based on the charge transferred from the first right electrode 60R1 fluctuates due to the installation environment, it is estimated that the capacitance value equivalent to the stray capacitance Ce measured based on the charge transferred from the corresponding dummy electrode 60R1d also fluctuates due to the installation environment.

[0056] When the measurement unit 68 stops calculating the capacitance base value n because the most recent capacitance difference value n calculated using the above formula (2) exceeds a predetermined judgment threshold, and repeats measuring the capacitance value n and calculating the capacitance difference value n using the above formula (3) at predetermined time intervals, the measurement unit 68 repeats measuring the capacitance value based on the charge moved from the dummy electrode (called the dummy capacitance value dn) at the above predetermined time intervals in parallel with measuring the capacitance value n.

[0057] If the dummy capacitance value dn fluctuates (changes by a predetermined value or more from the previous measurement value (10 msec ago)), the capacitance base value p is corrected using a correction value Δ×α obtained by multiplying the fluctuation range Δ by a predetermined coefficient α (corresponding to the surface area ratio between the dummy electrode and the corresponding electrode, which is 100 in the above example). For example, if the capacitance has increased from the previous measurement value, the capacitance difference value n is calculated using the above equation (3) using the corrected capacitance base value (p+Δ×α) obtained by adding the correction value Δ×α to the previous capacitance base value p. On the other hand, if the capacitance has decreased from the previous measurement value, the capacitance difference value n is calculated using the above equation (3) using the corrected capacitance base value (p-Δ×α) obtained by subtracting the correction value Δ×α from the previous capacitance base value p.

[0058] As a result, even if the floating capacitance Ce of the floating capacitor E changes due to environmental changes such as temperature while the calculation of the capacitance base value n is stopped, it is possible to appropriately calculate the capacitance difference value n (i.e., the electrostatic capacitance Ch of the human body H) using the corrected capacitance base value (p±Δ×α) corrected based on the fluctuation range of the dummy capacitance value dn.

[0059] In the above explanation, the sensor unit 62R1 has been used as an example to represent the eight sensor units 62L1 to 62L4 and 62R1 to 62R4, but the same applies when measuring the capacitance Ch with the other sensor units 62R2 to 62R4 and 62L1 to 62L4. However, the weight value WT in the above equation (1) and the predetermined judgment threshold value to be compared with the capacitance difference value n calculated by the above equations (2) and (3) may be changed appropriately for each sensor unit.

[0060] According to the embodiment described above, the following effects can be obtained. (1) The steering device 1 includes a steering wheel 2 and a sensor unit 62 that detects contact or proximity of a human body with the steering wheel 2. The sensor unit 62R1 includes a plurality of electrodes 60 (e.g., 60R1 to 60R4) provided on the steering wheel 2, and dummy electrodes 60R1d to 60R4d as correction electrodes arranged on the surfaces of the electrodes 60R1 to 60R4 to correct capacitance values ​​based on the electrodes 60R1 to 60R4. This configuration makes it possible to appropriately detect the grip of the steering wheel 2. Specifically, since the dummy electrodes 60R1d-60R4d can be considered to be in substantially the same installation environment as the electrodes 60R1-60R4, when the capacitance value based on the electrodes 60R1-60R4 changes due to temperature or the like, it is possible to correct the capacitance value based on the electrodes 60R1-60R4 based on the change in the capacitance value based on the dummy electrodes 60R1d-60R4d. This makes it possible to detect the grip of the steering wheel 2 in accordance with the characteristics of each sensor unit 62 including each of the electrodes 60R1-60R4.

[0061] (2) In the steering device 1 described above in (1), the dummy electrodes 60R1d to 60R4d are arranged in the longitudinal direction along the surfaces of the electrodes 60R1 to 60R4. This configuration makes it possible to arrange the longer dummy electrodes 60R1d-60R4d along the surfaces of the electrodes 60R1-60R4. This allows the dummy electrodes 60R1d-60R4d to be installed in substantially the same installation environment as the electrodes 60R1-60R4, making it possible to detect gripping of the steering wheel 2 in accordance with the characteristics of each sensor unit 62 including each of the electrodes 60R1-60R4.

[0062] (3) In the steering device 1 described above in (2), the dummy electrodes 60R1d to 60R4d are linearly formed along the surfaces of the electrodes 60R1 to 60R4. With this configuration, the area of ​​each of the dummy electrodes 60R1d to 60R4d can be reduced (for example, to 1 / 100 of the above), which makes it possible to arrange each of the dummy electrodes 60R1d to 60R4d so as to reduce the effect on each of the electrodes 60R1 to 60R4.

[0063] (4) In the steering device 1 of (3) above, the steering handle 2 comprises an annular rim portion 20, a hub portion 23 provided inside the rim portion 20, and spoke portions 25L, 25R, 25D extending radially from the hub portion 23 to the rim portion 20 and connecting the hub portion 23 to the inner peripheral portion 21 of the rim portion 20, and for example, the sensor unit 62R1 is arranged in the right accessory operation console unit (right-side function switch portion) 5R arranged in the right spoke portion 25R. Generally, it is easier to ensure a larger space within the spokes than within the rim, so by using the configuration described in (4) above, productivity can be improved compared to when the sensor unit is insert-molded into the steering wheel rim.

[0064] (5) In the steering device 1 of (4) above, each spoke portion 25L, 25R, 25D is provided in multiple locations between the rim portion 20 and the hub portion 23 that are gripped by the occupant, and for example, the sensor units 62L1 to 62L4, 62R1 to 62R4 are respectively arranged on the left spoke portion 25L and the right spoke portion 25R of the multiple spoke portions 25L, 25R, 25D when viewed from the front from the driver's seat, and are also arranged close to switches and the like as components for performing at least one of vehicle information operations or driving assistance function operations within the left auxiliary operation console unit (left-side function switch portion) 5L and the right auxiliary operation console unit (right-side function switch portion) 5R. With this configuration, by placing the PCBs of sensor units 62L1 to 62L4 and 62R1 to 62R4 on the left accessory operation console unit (left side function switch unit) 5L and the right accessory operation console unit (right side function switch unit) 5R, which are arranged in pairs on the left spoke portion 25L and the right spoke portion 25R, respectively, it becomes possible to properly detect gripping within the recommended gripping range on the left and right sides of the rim portion 20.

[0065] The above embodiment can be modified in various ways, and modifications will be described below. (Variation 1) In the embodiment, an annular steering wheel is exemplified as the steering handle 2, but the present invention may also be applied to cases where a non-annular, rectangular, or rod-shaped steering handle is used.

[0066] (Variation 2) In the embodiment, eight electrodes 60 are exemplified, namely, the first left electrode 60L1 to the fourth left electrode 60L4 and the first right electrode 60R1 to the fourth right electrode 60R4, but the number of electrodes may be more or less than the eight exemplified. Furthermore, eight sensor units 62L1 to 62L4 and 62R1 to 62R4 are illustrated corresponding to the eight electrodes 60L1 to 60L4 and 60R1 to 60R4, but the number of sensor units 62 may be increased or decreased depending on the number of electrodes 60. Furthermore, although the embodiment has been described with reference to a case where one sensor unit 62 corresponds to one electrode 60, multiple electrodes 60 may correspond to one sensor unit 62. For example, one sensor unit 62 arranged in the left spoke portion 25L on the left side in a front view corresponds to the first left electrode 60L1 to the fourth left electrode 60L4, and another sensor unit 62 arranged in the right spoke portion 25R on the right side in a front view corresponds to the first right electrode 60R1 to the fourth right electrode 60R4. Furthermore, the left and right sensor units 62 may be integrated into one, and in that case, the integrated sensor unit 62 may be placed in either the left spoke portion 25L, the right spoke portion 25R, or the lower spoke portion 25D.

[0067] (Variation 3) In the steering device 1 according to the embodiment described above, the sensor unit 62 may further configure the measuring section 68 as a control section so that, in addition to the plurality of dummy electrodes 60R1d to 60R4d, the electrodes of the plurality of electrodes 60R1 to 60R4 provided on the steering wheel 2 that have not accumulated charge due to contact with or proximity to a human body are used to correct the capacitance value based on the other electrodes that have accumulated charge. With this configuration, it is possible to use, among the electrodes 60R1 to 60R4, electrodes that have not accumulated charge due to contact with or proximity to the human body in place of the dummy electrodes 60R1d to 60R4d, thereby increasing redundancy in detecting grip of the steering wheel 2.

[0068] (Variation 4) Thermistor elements may be provided instead of the dummy electrodes 60R1d to 60R4d. As a specific example, four thermistor elements are arranged along the plate-like electrode surfaces of the electrodes 60R1, 60R2, 60R3, and 60R4 illustrated in FIG. 4B while being insulated from the electrodes 60R1, 60R2, 60R3, and 60R4. The measuring unit 68 detects the ambient temperatures of the electrodes 60R1, 60R2, 60R3, and 60R4 based on the resistance values ​​of the thermistors, selects a correction coefficient to be used for correction from among a plurality of correction coefficients prepared in advance, and calculates the capacitance difference value n according to the above equation (3) using the corrected capacitance base value (p±correction coefficient).

[0069] According to the above-described variant example 4, even if the floating capacitance Ce of the floating capacitor E changes due to environmental changes such as temperature while the calculation of the capacitance base value n is stopped, it is possible to appropriately calculate the capacitance difference value n (i.e., the electrostatic capacitance Ch of the human body H) using the corrected capacitance base value (p±correction coefficient) corrected with a correction coefficient selected based on the change in the resistance value of the thermistor element.

[0070] The above description is merely an example, and the present invention is not limited to the above-described embodiment and modifications as long as the features of the present invention are not impaired. One or more of the above-described embodiment and modifications can be arbitrarily combined, and modifications can also be combined with each other. [Explanation of symbols]

[0071] 1 steering device, 2 steering handle, 5L left auxiliary operation console unit (function switch section), 5R right auxiliary operation console unit (function switch section), 6 grip detection device, 20 rim section, 23 hub section, 25L left spoke section, 25R right spoke section, 60 electrode, 60L1 first left electrode, 60L2 second left electrode, 60L3 third left electrode, 60L4 fourth left electrode, 60R1 first right electrode, 60R2 second right electrode, 60R3 third right electrode, 60R4 fourth right electrode, 60R1d, 60R2d, 60R3d, 60R4d dummy electrodes, 61L1, 61L2, 61L3, 61L4 left wiring, 61R1, 61R2, 61R3, 61R4 Right wiring, 62 (62L1, 62L2, 62L3, 62L4, 62R1, 62R2, 62R3, 62R4) sensor unit, 63 pulse power supply, 64 amplifier, 65 charging capacitor, 67 control unit, 68 measurement unit, 69 detection unit, Ce stray capacitance, Ch electrostatic capacitance, H human body, RL1, RL2, RL3, RL4, RR1, RR2, RR3, RR4 grip detection range, SW1 first switch, SW2 second switch

Claims

1. A steering device comprising a steering wheel and a sensor unit that detects contact or proximity of a human body with the steering wheel, The sensor unit includes: a plurality of electrodes provided on the steering wheel; a plurality of correction electrodes arranged on a surface of the electrode for correcting a capacitance value based on the electrode; The correction electrode is disposed in the longitudinal direction along the surface of the electrode. A steering device characterized by:

2. A steering device comprising a steering handle and a sensor unit that detects contact or proximity of a human body with the steering handle, The sensor unit includes: a plurality of electrodes provided on the steering wheel; a plurality of correction electrodes arranged on a surface of the electrode for correcting a capacitance value based on the electrode; The sensor unit further comprises: a control unit that uses, in addition to the plurality of correction electrodes, electrodes among the plurality of electrodes provided on the steering wheel in which no charge has been accumulated due to contact with or proximity to a human body, for correcting a capacitance value based on the other electrodes in which charge has been accumulated. A steering device characterized by:

3. A steering device comprising a steering handle and a sensor unit that detects contact or proximity of a human body with the steering handle, The sensor unit includes: a plurality of electrodes provided on the steering wheel; a plurality of correction electrodes arranged on a surface of the electrode for correcting a capacitance value based on the electrode; The correction electrode is linearly formed along the surface of the electrode. A steering device characterized by:

4. 2. The steering device according to claim 1, the steering wheel includes an annular rim portion, a hub portion provided inside the rim portion, and spoke portions extending from the hub portion in a radial direction of the rim portion and connecting the hub portion and an inner peripheral portion of the rim portion, The sensor unit is disposed in a function switch portion disposed in the spoke portion. A steering device characterized by:

5. 5. The steering device according to claim 4, the spoke portion is provided in plurality between the rim portion and the hub portion, which are gripped by a rider; The sensor units are respectively disposed on the left and right spoke portions of the plurality of spoke portions as viewed from the front of the driver's seat, and are disposed in the vicinity of components for performing at least one of vehicle information operation and driving assistance function operation within the function switch portion. A steering device characterized by:

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