Steering system

Abstract

The system accurately determines whether the steering wheel is being held or not. [Solution] The steering device 50 includes sensor units 13L, 13R that detect contact or proximity of a human body in a plurality of detection target areas provided on the steering wheel, a grip determination unit 112 that compares the output values ​​of the sensor units 13L, 13R with a determination threshold to determine whether or not the steering wheel 2 is being gripped, a specification unit 111 that identifies a water-exposed area from the plurality of detection target areas based on the output values ​​of the sensor units 13L, 13R, and a threshold setting unit 113 that, when a water-exposed area is identified by the specification unit 111, changes the determination threshold from a first value determined before the water-exposed area was identified to a second value different from the first value. The grip determination unit 112 compares the output value of the sensor unit corresponding to an area other than the water-exposed area with the determination threshold changed to the second value to determine whether or not the steering wheel is being gripped.

Description

Technical Field

[0001] The present invention relates to a steering device having a function of detecting the grip of a steering wheel by an occupant.

Background Art

[0002] In recent years, efforts have been actively made to provide access to a sustainable transportation system that takes into account people in vulnerable positions among traffic participants. Toward this realization, research and development focusing on further improving traffic safety and convenience through research and development of driving support technologies have been carried out. Conventionally, there has been known a device that compares the measured value of a capacitance sensor provided on a steering wheel with a threshold value to determine the gripped / non-gripped state (see, for example, Patent Document 1). In the device described in Patent Document 1, the threshold value is updated according to the difference between the previous value and the current value of the measured value.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] According to the device described in Patent Document 1 above, the threshold value can be updated following the change over time of the measured value due to disturbances such as temperature and humidity. However, if the threshold value is updated based on the difference between the previous value and the current value, there is a risk that determination processing based on an abnormal output value will continue when a normal output value cannot be obtained from the sensor, such as when the steering wheel is waterlogged.

Means for Solving the Problems

[0005] A steering device according to one aspect of the present invention includes: a plurality of sensor units, each containing a plurality of sensors, that detect contact or proximity of a human body in a plurality of detection target areas provided on the steering wheel; a grip determination unit that compares the output value of each of the plurality of sensor units with a determination threshold to determine whether or not the steering wheel is being gripped; a water-damaged area identification unit that identifies a water-damaged detection target area, which is one of the plurality of detection target areas, based on the output values ​​of the plurality of sensor units; and a threshold setting unit that, when a water-damaged detection target area is identified by the water-damaged area identification unit, changes the determination threshold from a first value determined before the water-damaged detection target area was identified to a second value different from the first value. The grip determination unit defines a sensor unit corresponding to the water-damaged detection target area identified by the water-damaged area identification unit as a first sensor unit, and a sensor unit corresponding to an area other than the water-damaged detection target area as a second sensor unit, and determines whether or not the steering wheel is being gripped by comparing the output value of the second sensor unit with the determination threshold changed to the second value. [Effects of the Invention]

[0006] According to the present invention, the gripping and non-gripping states of the steering wheel can be determined with high accuracy. [Brief explanation of the drawing]

[0007] [Figure 1A] A front view of a steering wheel to which a steering device according to an embodiment of the present invention is applied. [Figure 1B] Figure 1A shows an example of electrodes embedded in the spokes of the steering wheel. [Figure 2] Figure 1A shows what happens when a beverage is spilled on the steering wheel. [Figure 3] A block diagram showing the main components of a steering device according to an embodiment of the present invention. [Figure 4] A diagram illustrating the expansion of the flooded area. [Figure 5]Figure 3 shows an example of the configuration of a driver assistance system equipped with a steering device. [Figure 6] A flowchart showing an example of the processing performed by the controller's CPU in Figure 3. [Modes for carrying out the invention]

[0008] The embodiments of the invention will now be described with reference to the drawings. Figure 1A is a front view of a steering wheel to which the steering device according to an embodiment of the present invention is applied. The steering device according to an embodiment of the present invention can be applied to a manually driven vehicle equipped with a driver assistance system such as ADAS (Advanced driver-assistance systems). The vehicle to which the steering device according to this embodiment is applied may be referred to as "the vehicle" to distinguish it from other vehicles. The steering wheel 2 in Figure 1A is operated by the driver in the driver's seat of the vehicle. In a front view (as seen from the driver's perspective), a steering shaft 3 that pivotally supports the steering wheel 2 is connected to the rear side of the steering wheel 2.

[0009] As shown in Figure 1A, the steering handle 2 is an irregularly shaped handle and comprises a hub portion 21, a rim portion (grip portion) 22, and spoke portions 23 connecting the hub portion 21 and the rim portion 22. The rim portion 22 includes a pair of left and right rim portions (vertical portions) 22L, 22R extending substantially vertically to the left and right of the hub portion 21, and a horizontal portion 22H extending substantially horizontally below the hub portion 21 and connecting the rim portions (vertical portions) 22L, 22R. The spoke portion 23 includes horizontal portions 23L, 23R connecting the hub portion 21 and the rim portions (vertical portions) 22L, 22R, and a vertical portion 23V connecting the hub portion 21 and the horizontal portion 22H. The rim portion (vertical portion) 22L is provided such that its end portion 24L protrudes above the connection portion 25L between the spoke portion (horizontal portion) 23L and the rim portion (vertical portion) 22L. Similarly, the rim portion (vertical portion) 22R is provided such that its end portion 24R protrudes above the connection portion 25R between the spoke portion (horizontal portion) 23R and the rim portion (vertical portion) 22R.

[0010] As shown in Figure 1A, the spoke sections 23L and 23R are each provided with operation console units (hereinafter also referred to as function switch units) 5L and 5R, respectively, for the driver to operate vehicle auxiliary equipment (navigation system, audio system, air conditioning system, etc.) and ADAS functions (not shown). The driver can operate the vehicle auxiliary equipment, etc., by operating the multiple switches provided on the operation console units 5L and 5R with their fingers.

[0011] Figure 1B shows an example of electrodes built into the spoke section. For clarity of the drawing, the operating console units 5L and 5R are omitted in Figure 1B. The hub section 21 incorporates conductive, plate-shaped electrodes 26L0 to 26L5 and 26R0 to 26R5. Electrodes 26L0 to 26L5 are located near the recommended gripping area HL for the left hand, defined for the rim section 22 of the steering handle 2. As shown in Figure 1B, electrode 26L0 is provided along the upper left side wall surface of the hub section 21. Electrode 26L1 is provided along the left side wall surface of the hub section 21. Electrode 26L2 is provided along the lower left corner side wall surface of the hub section 21. Electrodes 26L3 to 26L5 are provided adjacent to electrode 26L2 along the lower left side wall surface of the hub section 21, sequentially toward the center of the hub section 21. Regions RL0 to RL5 represent the detection area of ​​electrodes 26L0 to 26L5. As shown in Figure 1B, electrodes 26L0 to 26L5 are positioned so that the detection area RL0 to RL5 covers the entire recommended gripping area HL.

[0012] Electrodes 26R0 to 26R5 are provided near the recommended gripping area HR for the right hand, defined for the rim portion 22 of the steering handle 2. As shown in Figure 1B, electrode 26R0 is provided along the upper right side wall surface of the hub portion 21. Electrode 26R1 is provided along the right side wall surface of the hub portion 21. Electrode 26R2 is provided along the lower right corner side wall surface of the hub portion 21. Electrodes 26R3 to 26R5 are provided sequentially along the lower right side wall surface of the hub portion 21, adjacent to electrode 26R2, toward the center of the hub portion 21. Regions RR0 to RR5 represent the detection target areas of electrodes 26R0 to 26R5. As shown in Figure 1B, electrodes 26R0 to 26R5 are arranged so that regions RR0 to RR5 cover the entire recommended gripping area HR.

[0013] The electrodes 26 (26L0~26L5, 26R0~26R5) are connected via signal lines (not shown) to the gripping sensors 13L0~13L5 and 13R0~13R5 of the sensor units 13L and 13R shown in Figure 3, which will be described later.

[0014] Figure 3 is a block diagram showing the main components of the steering device according to this embodiment. As shown in Figure 3, the steering device 50 includes a controller 10, sensor units 13L and 13R, a steering torque sensor (hereinafter simply referred to as a torque sensor) 14, a steering angle sensor 15, a communication unit 16, and an output device 17. The communication unit 16 connects the steering device 50 to a communication network such as CAN (Controller Area Network). The steering device 50 can communicate with in-vehicle devices (not shown) via CAN communication or the like through the communication unit 16. The steering device 50 may also be able to communicate with in-vehicle devices or external devices (not shown) via a wireless communication network.

[0015] The sensor unit 13L has gripping sensors 13L0 to 13L5 respectively connected to the electrodes 26L0 to 26L5 in FIG. 1B via signal lines not shown. The sensor unit 13R has gripping sensors 13R0 to 13R5 respectively connected to the electrodes 26R0 to 26R5 in FIG. 1B via signal lines not shown. The gripping sensors 13L0 to 13L5 and 13R0 to 13R5 respectively detect the electrical characteristics (for example, the capacitance between the electrode and the ground (for example, the vehicle body)) of the electrodes 26L0 to 26L5 and 26R0 to 26R5.

[0016] The torque sensor 14 detects the torque around the rotation axis of the steering wheel 2 input by the driver, that is, the steering torque.

[0017] The steering angle sensor 15 detects the steering angle corresponding to the driver's steering operation. The steering angle is represented as an angle in the clockwise direction centered on the steering shaft 3 and based on the central position in the left - right direction of the upper end of the hub portion 21 as viewed from the driver. Also, the neutral position (0 [deg]) of the steering wheel 2 is a position where the steering wheel 2 is not operated in either the clockwise or counter - clockwise rotation direction and the steering wheel (front wheel, rear wheel, or front and rear wheels) of the own vehicle is not steered to either the left or the right.

[0018] The output device 17 is a general term for devices that output information to the driver. The output device 17 includes a display that provides information to the driver via a display image, a speaker that provides information to the driver by voice, and the like.

[0019] By the way, capacitance sensors such as the gripping sensors 13L0 to 13L5 and 13R0 to 13R5 have the characteristic that their detection sensitivity increases due to water or moisture. FIG. 2 is a diagram showing the state when a beverage spills on the steering wheel 2. In FIG. 2, it is shown that the beverage WR spilled from the container (can) CA drips downward from the end portion 24R along the rim portion 22R and below the rim portion 22R. Hereinafter, as shown in FIG. 2, the situation where the steering wheel 2 gets wet due to a liquid such as water is expressed as the steering wheel 2 being wetted.

[0020] As shown in FIG. 2, when a beverage is splashed on the surface of the steering handle 2 or the driver holds the steering handle 2 with wet hands, causing the steering handle 2 to be wetted, the electrodes corresponding to the wetted area will have a higher detection sensitivity due to the above characteristics. In the example of FIG. 2, the detection sensitivities of the electrodes 26R0 and 26R1 corresponding to the wetted areas RR0 and RR1 are increased. Therefore, when determining the grip on the steering handle 2 based on the magnitude of the capacitance detected by the electrodes, if the steering handle 2 is wetted, there is a risk of erroneously determining that the steering handle 2 is being gripped even though it is not. Thus, to address such a problem, in this embodiment, the controller 10 of the steering device 50 is configured as follows.

[0021] The controller 10 includes an arithmetic unit 11 such as a CPU (microprocessor) and a storage unit 12. Functionally, the arithmetic unit 11 has a water-affected area specifying unit (hereinafter also simply referred to as the specifying unit) 111, a grip determination unit 112, a threshold setting unit 113, a prediction unit 114, and a notification unit 115. The storage unit 12 stores various control programs and information such as thresholds used in the programs.

[0022] The specifying unit 111 specifies the wetted recommended grip area (hereinafter referred to as the water-affected area) in the recommended grip areas HL and HR based on the output values of the grip sensors of the sensor units 13L and 13R. Specifically, when the output value of any one of the grip sensors included in the output value of the sensor unit is equal to or greater than a predetermined value PC, the specifying unit 111 specifies the corresponding recommended grip area as the water-affected area. The output value of the sensor unit 13L is a value obtained by integrating the output values (detection values) of the grip sensors 13L0 to 13L5. The output value of the sensor unit 13R is a value obtained by integrating the output values (detection values) of the grip sensors 13R0 to 13R5. The predetermined value PC may be set to a value indicating a detection error of the grip sensor, or may be a value measured in advance through experiments or the like.

[0023] The grip determination unit 112 detects whether or not a human body is in contact with the recommended gripping areas HL and HR based on whether or not the output values ​​of the sensor units 13L and 13R are equal to or greater than the determination threshold C_Th. If the grip determination unit 112 detects human body contact with either of the recommended gripping areas HL or HR, it determines that the steering wheel 2 is being gripped by the driver.

[0024] Furthermore, if proximity of a human body to the recommended gripping areas HL and HR (approaching motion within a predetermined distance) is detected, it can be determined that the driver is in a state where they can immediately grip the steering wheel 2. Therefore, the gripping determination unit 112 may also determine that the steering wheel 2 is being gripped by the driver if proximity of a human body to either of the recommended gripping areas HL or HR is detected. In other words, the gripping determination unit 112 may determine that the steering wheel 2 is being gripped by the driver if it detects contact or proximity of a human body to either of the recommended gripping areas HL or HR. When contact or proximity to the recommended gripping areas HL and HR is detected, the determination threshold C_Th is set to a smaller value than when only contact to the recommended gripping areas HL and HR is detected.

[0025] When the water-covered area is identified by the identification unit 111, the threshold setting unit 113 changes the determination threshold C_Th used for the determination of the gripping determination unit 112 from the value Th1 determined before the water-covered area was identified by the identification unit 111 to a value Th2 that is different from value Th1. Value Th2 is smaller than value Th1, for example, half the value of value Th1.

[0026] When the threshold setting unit 113 changes the judgment threshold C_Th from value Th1 to value Th2, the gripping judgment unit 112 uses the output value of the sensor unit (in the example in Figure 2, sensor unit 13L) corresponding to the recommended gripping area that is not exposed to water (hereinafter referred to as the non-water-exposed area) to determine whether the steering handle 2 is being gripped. More specifically, the gripping judgment unit 112 compares the output value of the sensor unit corresponding to the non-water-exposed area with the judgment threshold C_Th (value Th2), and determines that the steering handle 2 is being gripped if the output value is equal to or greater than the judgment threshold C_Th (value Th2).

[0027] When the water-covered area is identified by the identification unit 111, the prediction unit 114 predicts that the detection target area (recommended gripping area) of the sensor unit located near the water-covered area may be covered in water in the future when the output value of the sensor unit located near the water-covered area gradually increases. In the example in Figure 2, immediately after the beverage WR spills from the container CA, only area RR0 is covered in water, but as the beverage WR drips down the rim portion 22R, area RR1 is covered in water. In this way, the water-covered area in the recommended gripping area HR gradually expands over time, and in some cases extends to the recommended gripping area HL which is not covered in water.

[0028] Figure 4 is a diagram illustrating the expansion of the water-covered area. As shown in Figure 4, when the steering handle 2 is operated counterclockwise with the beverage WR spilled (Figure 2), the beverage WR reaches the recommended gripping area HL, which is outside the water-covered area. Subsequently, as the water-covered area within the recommended gripping area HL expands over time, the output value of the sensor unit 13L corresponding to the recommended gripping area HL gradually increases. When the identification unit 111 identifies the recommended gripping area HR as a water-covered area, the prediction unit 114 monitors (acquires at predetermined intervals) the output value of other sensor units (in the example of Figure 4, sensor unit 13L) located near the sensor unit 13R corresponding to the water-covered area (recommended gripping area HR). As a result of the monitoring, when the prediction unit 114 recognizes a gradual increase in the output value of sensor unit 13L, it predicts that the detection target area (recommended gripping area) HL of sensor unit 13L may be covered in water in the future.

[0029] If both the recommended gripping areas HL and HR are submerged in water, the gripping determination unit 112 will be unable to accurately determine whether the steering handle 2 is being gripped. Therefore, if both the recommended gripping areas HL and HR are submerged in water, the gripping determination unit 112 uses the detected value of the torque sensor 14 instead of the output values ​​of the sensor units 13L and 13R to determine whether the steering handle 2 is being gripped. Specifically, after the prediction unit 114 predicts that the recommended gripping area HL may be submerged in water in the future, if the output value of any of the gripping sensors 13L0 to 13L5 of the sensor unit 13L exceeds a predetermined value PC, the gripping determination unit 112 determines that both the recommended gripping areas HL and HR are submerged in water. Once it is determined that both the recommended gripping areas HL and HR are submerged in water, the gripping determination unit 112 starts determining whether the steering handle 2 is being gripped based on whether the detected value of the torque sensor 14 is equal to or greater than the determination threshold T_Th. The judgment threshold T_Th is set to a value smaller than the torque sensor's detected value (hereinafter referred to as the reference detected value) when the output value of sensor units 13L and 13R is value Th1. The reference detected value is measured in advance through experiments or other means.

[0030] The notification unit 115 generates information indicating the gripping state (hereinafter referred to as gripping state information) based on the determination result of the gripping determination unit 112. When the gripping determination unit 112 determines that the steering wheel 2 is being gripped, the notification unit 115 generates gripping state information indicating "Grip (Normal)" as the gripping state. Conversely, when the gripping determination unit 112 determines that the steering wheel 2 is not being gripped, the notification unit 115 generates gripping state information indicating "Not Gripped" as the gripping state. The notification unit 115 outputs the generated gripping state information to the output device 17 mounted on the vehicle.

[0031] Furthermore, when the notification unit 115 generates gripping status information indicating "not gripping," it may include warning information in the gripping status information to prompt the driver to grip the steering wheel 2. The warning information may include display information and audio information output to a display or speaker, as well as signals to illuminate or flash warning lights provided on or around the steering wheel 2 (instrument panel, etc.). The notification unit 115 may also output the gripping status information to an in-vehicle device or an external device via the communication unit 16.

[0032] Figure 5 shows an example of the configuration of a driver assistance system 1 equipped with a steering device 50 according to this embodiment. As shown in Figure 5, the driver assistance system 1 comprises a steering device 50 and a driver assistance device 70, which is one of the in-vehicle devices. The steering device 50 is connected to the driver assistance device 70 via a CAN bus 60 so as to be able to communicate.

[0033] The driver assistance system 70 is comprised of an electronic control unit (ECU). The driver assistance system 70 includes a calculation unit 71 such as a CPU (microprocessor) and a storage unit 72. Functionally, the calculation unit 71 has a driving control unit 711. The storage unit 72 stores information such as programs for various controls and thresholds used in the programs. The driving control unit 711 controls driving actuators (not shown) based on information obtained from on-board sensors (such as camera images). Driving actuators include a throttle actuator that adjusts the opening degree of the engine's throttle valve (throttle opening), a brake actuator that operates the vehicle's braking system, and a steering actuator that drives the steering system.

[0034] The driver assistance system 70 has various driver assistance functions such as LKAS and ACC (Adaptive Cruise Control). When LKAS is enabled, the driving control unit 711 recognizes the lane markings that define the vehicle's lane based on information obtained from on-board sensors and controls the steering actuator so that the vehicle travels near the center of its lane.

[0035] At this time, the driving control unit 711 acquires grip state information output from the notification unit 115 of the steering device 50 via the CAN bus 60, and recognizes the grip state of the steering wheel 2 based on the grip state information. When it recognizes that the driver is not gripping the steering wheel 2, the driving control unit 711 temporarily stops the driving assistance (steering assistance) by LKAS. If the driver's non-grip state continues for a predetermined time, the driving control unit 711 cancels the steering assistance. If the driver's grip on the steering wheel 2 is recognized before the predetermined time has passed, the temporarily stopped steering assistance is restarted. In this way, the grip state information output from the steering device 50 is used to control the driving assistance functions of the driving assistance device 70, such as temporarily stopping, restarting, and canceling them.

[0036] Figure 6 is a flowchart showing an example of a process executed by the CPU of the controller 10 in Figure 3 according to a predetermined program. The process shown in this flowchart is executed at predetermined intervals, for example, when the vehicle is in motion.

[0037] First, in step S1, the controller 10 acquires the output values ​​of sensor units 13L and 13R. Specifically, the controller 10 integrates the output values ​​of gripping sensors 13L0 to 13L5 and acquires the result as the output value of sensor unit 13L. The controller 10 also integrates the output values ​​of gripping sensors 13R0 to 13R5 and acquires the result as the output value of sensor unit 13R. In step S2, it is determined whether either sensor unit 13L or 13R contains a gripping sensor whose output value is equal to or greater than a predetermined value PC.

[0038] If the result in step S2 is negative, the controller 10 determines that neither of the recommended gripping areas HL and HR corresponding to the sensor units 13L and 13R are exposed to water, and proceeds to step S3. In step S3, the controller 10 determines whether the output value of either sensor unit 13L or 13R is greater than or equal to the judgment threshold C_Th. Initially, the judgment threshold C_Th is set to the value Th1. If the judgment threshold C_Th is set to the value Th2, the controller 10 changes the judgment threshold C_Th from Th2 to Th1 before executing the judgment process in step S3.

[0039] If the result in step S3 is positive, the controller 10 determines in step S4 that the steering wheel 2 is being held by the driver and generates gripping status information indicating "gripping (normal)". On the other hand, if the result in step S3 is negative, the controller 10 determines in step S5 that the steering wheel 2 is not being held by the driver and generates gripping status information indicating "not gripping".

[0040] On the other hand, if the result in step S2 is positive, the controller 10 identifies the recommended gripping area corresponding to the sensor unit including the gripping sensor whose output value is equal to or greater than a predetermined value PC as the water-exposed area, and proceeds to the process in step S6. In step S6, the controller 10 changes the judgment threshold C_Th from value Th1 to value Th2. In step S7, the controller 10 determines whether the output value of the sensor unit corresponding to the non-water-exposed area is equal to or greater than the judgment threshold C_Th (value Th2).

[0041] If the result in step S7 is positive, in step S8 the controller 10 determines that the steering wheel 2 is being held by the driver and generates gripping status information indicating "gripped (normal)". On the other hand, if the result in step S7 is negative, in step S9 the controller 10 determines that the steering wheel 2 is not being held by the driver and generates gripping status information indicating "not gripped".

[0042] Finally, in step S10, the controller 10 outputs the gripping state information generated in steps S4, S5, S8, or S9 to the output device 17 and terminates the process.

[0043] According to the embodiments described above, the following effects and advantages can be obtained. (1) The steering device 50 includes sensor units 13L, 13R, which include grip sensors 13L0~13L5, 13R0~13R5 that detect contact or proximity of a human body in the detection target area (recommended gripping areas HL, HR in Figure 1B) provided on the steering handle 2; a grip determination unit 112 that compares the output values ​​of each of the sensor units 13L, 13R with a determination threshold C_Th to determine whether or not the steering handle 2 is being gripped; a specification unit 111 that identifies a water-damaged area (hereinafter also referred to as a water-damaged detection target area) among the detection target areas HL, HR based on the output values ​​of the sensor units 13L, 13R; and a threshold setting unit 113 that, when a water-damaged area is identified by the specification unit 111, changes the determination threshold C_Th from a value Th1 determined before the water-damaged area was identified by the specification unit 111 to a value Th2 (< value Th1) that is different from value Th1. The grip determination unit 112 defines the sensor unit corresponding to the water-covered area identified by the water-covered area identification unit as the first sensor unit, and the sensor unit corresponding to an area other than the water-covered area as the second sensor unit. The grip determination unit 112 compares the output value of the second sensor unit with the determination threshold C_Th, which has been changed to value Th2, to determine whether or not the steering handle 2 is being gripped. The grip determination unit 112 determines that the steering handle 2 is being gripped if the output value of the second sensor unit is equal to or greater than the determination threshold C_Th (value Th2). The detection target areas HL and HR are provided at different positions on the steering handle 2. The grip sensors 13L0 to 13L5 detect human body contact or proximity in each area RL0 to RL5 and RR0 to RR5 obtained by dividing the detection target area HL. The grip sensors 13R0 to 13R5 detect human body contact or proximity in each area RR0 to RR5 obtained by dividing the detection target area HR. The output value of sensor unit 13L is the integrated value of the output values ​​of gripping sensors 13L0 to 13L5, and the output value of sensor unit 13R is the integrated value of the output values ​​of gripping sensors 13R0 to 13R5.

[0044] Incidentally, the second sensor unit, which corresponds to the recommended gripping area that is not submerged in water (the non-submerged area), is located at a distance from the recommended gripping area that is submerged in water (the submerged area). Therefore, the response of the sensor electrodes of the second sensor unit in the submerged area decreases in proportion to the distance. Consequently, it is difficult for the second sensor unit to accurately detect contact or proximity of a human body to the submerged area. However, as described above, by lowering the threshold for gripping determination when water is detected on the steering handle 2, the output value of the second sensor unit can be used to accurately detect not only contact or proximity of a human body in the non-submerged area, but also contact or proximity of a human body in the submerged area. This makes it possible to suppress misjudgment of gripping / non-gripping status due to water exposure, even when the recommended gripping area is submerged in water and normal output values ​​cannot be obtained from the corresponding sensor unit.

[0045] (2) The steering device 50 further includes an output device 17 that outputs information, and a notification unit 115 that notifies the driver of the information generated based on the judgment result of the grip determination unit 112 via the output device 17. This allows the driver to recognize the result of the grip determination. Furthermore, the result of the grip determination can be used for driver assistance functions such as LKAS. As a result, safety during steering can be improved.

[0046] (3) The identification unit 111 identifies the detection target area corresponding to the sensor unit among the sensor units 13L and 13R that includes a gripping sensor whose output value is equal to or greater than a predetermined value PC as the water-covered area. The threshold setting unit 113 changes the judgment threshold C_Th from value Th2 to value Th1 when the output values ​​of all sensors included in the first sensor unit fall below a predetermined value. As a result, when the water-covered state is resolved after water exposure by the driver wiping the surface of the steering wheel 2 or by natural evaporation of moisture, the threshold for gripping determination is returned to its initial value (default value), and gripping determination based on the output values ​​of both sensor units 13L and 13R is resumed. As a result, gripping determination after water exposure can be continued with the same accuracy as before water exposure.

[0047] (4) The steering handle 2 includes a hub portion 21, a rim portion (gripping portion) 22 having a pair of left and right vertical portions 22L, 22R extending substantially vertically to the left and right of the hub portion 21, and a horizontal portion 22H extending substantially horizontally below the hub portion 21 and connecting the pair of left and right vertical portions 22L, 22R, and spoke portions 23L, 23R connecting the pair of left and right vertical portions 22L, 22R to the hub portion 21. Sensor units 13L, 13R (more specifically, electrodes of the gripping sensors included in the sensor units 13L, 13R) are arranged in close proximity to function switch portions 5L, 5R for operating vehicle information or driving assistance functions, which are respectively arranged on the left and right sides of the hub portion 21. In this way, by providing sensor units to the function switch portions arranged symmetrically on the hub portion 21, contact or proximity of the human body to the recommended gripping range arranged symmetrically on the rim portion 22 can be appropriately detected.

[0048] (5) The steering device 50 further includes a prediction unit 114 that predicts that the detection target area (non-water-covered area) of the second sensor unit may be exposed to water in the future when the output value of the second sensor unit located near the first sensor unit gradually increases after the water-covered area has been identified by the identification unit 111, and a torque sensor 14 that detects the steering torque acting on the shaft of the steering wheel 2. After the prediction unit 114 predicts that the detection target area (non-water-covered area) of the second sensor unit may be exposed to water in the future, the grip determination unit 112 determines whether the steering wheel 2 is being gripped based on the detection value of the torque sensor 14 if the output value of any grip sensor of the second sensor unit becomes greater than or equal to a predetermined value PC.

[0049] If the part of the steering wheel 2 that is submerged in water is the upper part, the submerged area may spread from the top to the bottom depending on the degree of submersion. Similarly, if the steering wheel 2 is rotated by steering by the driver or by the automatic steering function, the submerged area may also expand. When the submerged area of ​​the steering wheel 2 extends over a wide area in this way, the reliability of the gripping determination (by the capacitive sensor) decreases. However, when the submerged area expands to the non-submerged area, that is, when normal output values ​​cannot be obtained from any sensor unit, the detection value of the torque sensor 14 can be used as a substitute as described above, so that the gripping / non-gripping state can be accurately determined even when the entire steering wheel 2 is submerged in water.

[0050] (6) Sensor units 13L and 13R each include a capacitance sensor. The output values ​​of sensor units 13L and 13R include capacitance information detected by the capacitance sensor. The gripping determination unit 112 determines that the steering handle 2 is being gripped when the detected value of the torque sensor 14 is greater than or equal to the determination threshold T_Th. The determination threshold T_Th is set to a value smaller than the reference detected value (i.e., the detected value of the torque sensor 14 when the output value of sensor units 13L and 13R is value Th1). Unlike the capacitance sensor, which correlates with the electrical characteristics of the human body, the torque sensor determines contact when a load from the human body is applied to the steering handle 2. Therefore, by lowering the threshold compared to the determination threshold of the capacitance sensor, gripping can be determined with higher accuracy. Note that when using a torque sensor, the load is applied to the upper and lower parts of the steering handle 2, and the torque detected value tends to be larger compared to other positions. Therefore, the gripping position of the steering handle 2 may be recognized based on the output values ​​of the gripping sensors 13L0~13L5 and 13R0~13R5, and the judgment threshold T_Th may be appropriately changed according to the gripping position. The gripping position of the steering handle 2 may also be recognized based on other information.

[0051] The above embodiment can be modified into various forms. Modifications will be described below. In the above embodiment, the notification unit 115 generates gripping state information that indicates the determination result of the gripping determination unit 112. However, the notification unit may also generate information regarding the water-covered area identified by the identification unit 111 (hereinafter referred to as water-covered state information) in the gripping state information. The notification unit may also output the water-covered state information to the output device 17 together with the gripping state information. The water-covered state information includes information that allows identification of the water-covered area (display information, audio information, etc.). The water-covered state information may also include instruction information (display information, audio information, etc.) that instructs the occupant to wipe the water-covered area. Furthermore, in the above embodiment, when the driving control unit 711 recognizes that the driver is not gripping the steering wheel 2, it temporarily stops the driving assistance (steering assistance, etc.), and cancels the driving assistance if the non-grip state continues for a predetermined time. However, the driving control unit may temporarily suspend or cancel driving assistance based on water damage information output (transmitted) from the notification unit. For example, the driving control unit may temporarily suspend or cancel driving assistance depending on the location of the water damage, the size of the water damage area, the duration of the water damage, etc.

[0052] Furthermore, in the above embodiment, when the water-exposed area is identified by the identification unit 111, the prediction unit 114 predicts that the detection target area (non-water-exposed area) of the second sensor unit, when the output value of the second sensor unit located near the first sensor unit gradually increases, may be exposed to water in the future. However, the prediction unit may also predict the possibility of the non-water-exposed area being exposed to water in the future based on the sensor value of the steering angle sensor 15, along with or instead of the output value of the second sensor unit. For example, as in the example in Figure 2, when the recommended gripping area HR on the right side is identified as a water-exposed area, the prediction unit predicts that the recommended gripping area HR may be exposed to water in the future when the steering angle of the steering wheel 2 changes by a predetermined angle or more counterclockwise from the point of identification.

[0053] Furthermore, in the above embodiment, the sensor units 13L and 13R are configured to detect contact or proximity of a human body to the rim portion 22. However, the sensor units may also detect the gripping force applied to the rim portion 22. In this case, a pressure sensor is built into the rim portion 22, and the sensor unit detects the gripping force applied to the steering handle 2 based on the sensor value obtained from the pressure sensor via a signal line (not shown). The determination unit may determine whether or not the steering handle 2 is being gripped based on the magnitude of the gripping force detected by the pressure sensor, along with the output values ​​of the sensor units 13L and 13R, or instead of the output values ​​of the sensor units 13L and 13R. Note that sensors other than pressure sensors may be used to detect the gripping force applied to the steering handle 2.

[0054] Furthermore, in the above embodiment, the example given was that the controller 10 performs the process shown in Figure 6 while the vehicle is in motion. However, the controller 10 may start the process shown in Figure 6 when it receives a notification from the driver assistance device 70 indicating that a driver assistance function such as LKAS has been activated. Also, the controller 10 may refrain from performing the process shown in Figure 6 when the vehicle's speed is below a predetermined speed. Moreover, the controller 10 may refrain from performing the process shown in Figure 6 when a driver assistance function that does not require the driver to hold the steering wheel 2, such as an automatic parking function (parking assist system), is activated.

[0055] Furthermore, although an irregularly shaped steering wheel was exemplified as the steering wheel 2 in the above embodiment, the present invention can also be applied when using a steering wheel of other shapes (such as an annular shape). In addition, although the steering device 50 was applied to a manually driven vehicle equipped with ADAS in the above embodiment, the steering device 50 can also be applied to an autonomous vehicle.

[0056] The above description is merely an example, and the present invention is not limited by the embodiments and modifications described above, as long as the features of the present invention are not impaired. It is also possible to arbitrarily combine one or more of the above embodiments and modifications, and to combine modifications with each other. [Explanation of Symbols]

[0057] 1 Driving assistance system, 2 Steering wheel, 10 Controller, 11 Calculation unit, 12 Memory unit, 13L, 13R Sensor unit, 13L0~13L5, 13R0~13R5 Gripping sensors, 14 Torque sensor, 15 Steering angle sensor, 16 Communication unit, 17 Output device, 26, 26L0~26L5, 26R0~26R5 Electrodes, 70 Driving assistance device, 111 Identification unit (Water-covered area identification unit), 112 Gripping determination unit, 113 Threshold setting unit, 114 Prediction unit, 115 Notification unit

Claims

1. Multiple sensor units, each containing multiple sensors, are provided on the steering wheel to detect contact or proximity of a human body in multiple detection target areas. A grip determination unit compares the output values ​​of the plurality of sensor units with determination thresholds to determine whether or not the steering wheel is being gripped, A water-affected area identification unit identifies a water-affected detection target area, which is one of the multiple detection target areas that has been exposed to water, based on the output values ​​of the multiple sensor units. The system includes a threshold setting unit that, when the water-affected area identification unit identifies the water-affected area to be detected, changes the determination threshold from a first value determined before the water-affected area to be detected to a second value different from the first value, The grip determination unit defines a sensor unit corresponding to the water-exposed area identified by the water-exposed area identification unit as a first sensor unit, and a sensor unit corresponding to an area other than the water-exposed area as a second sensor unit, and determines whether or not the steering handle is being gripped by comparing the output value of the second sensor unit with the determination threshold changed to the second value.

2. In the steering device according to claim 1, The gripping determination unit determines that the steering handle is being gripped when the output value of any of the plurality of sensor units is equal to or greater than the determination threshold. The steering device is characterized in that, when the water-exposed area identification unit identifies the water-exposed area to be detected, the threshold setting unit changes the determination threshold from the first value to the second value which is smaller than the first value.

3. In the steering device according to claim 1, Each of the aforementioned multiple detection target areas is provided at a different position on the steering wheel. Each of the aforementioned multiple sensors detects contact or proximity of a human body in each region obtained by dividing a corresponding detection target region from the aforementioned multiple detection target regions. A steering device characterized in that the output values ​​of the plurality of sensor units are each the integrated value of the output values ​​of the plurality of sensors.

4. In the steering device according to claim 1, An output device that outputs information, A steering device further comprising a notification unit that notifies the driver of information generated based on the determination result by the grip determination unit via the output device.

5. In the steering device according to claim 2, The water-exposed area identification unit identifies the detection target area corresponding to a sensor unit among the plurality of sensor units, which includes a sensor whose output value is equal to or greater than a predetermined value, as the water-exposed area detection target area. The steering device is characterized in that the threshold setting unit changes the determination threshold from the second value to the first value when the output values ​​of all sensors included in the first sensor unit fall below the predetermined value.

6. In the steering device according to claim 1, The steering handle has a hub portion, a gripping portion having a pair of left and right vertical portions extending substantially vertically to the left and right of the hub portion and a horizontal portion extending substantially horizontally below the hub portion and connecting the pair of left and right vertical portions, and spoke portions connecting the pair of left and right vertical portions and the hub portion. The steering device is characterized in that the plurality of sensor units are arranged in close proximity to function switch sections for operating vehicle information or driving assistance functions, which are located on the left and right sides of the hub section, respectively.

7. In the steering device according to claim 1, A steering device further comprising a prediction unit that predicts that the detection target area of ​​the second sensor unit may be exposed to water in the future when the output value of the second sensor unit located near the first sensor unit gradually increases after the water exposure area identification unit has identified the water exposure target area.

8. In the steering device according to claim 7, The system further includes a torque sensor that detects the steering torque acting on the shaft of the steering wheel, The grip determination unit is characterized in that, after the prediction unit predicts that the detection target area of ​​the second sensor unit may be exposed to water in the future, if the output value of any of the multiple sensors included in the second sensor unit exceeds a predetermined value, the grip determination unit determines whether or not the steering handle is being gripped based on the detection value of the torque sensor.

9. In the steering device according to claim 8, The aforementioned determination threshold is the first determination threshold, Each of the aforementioned sensor units includes a plurality of capacitive sensors, The output values ​​of the plurality of sensor units include capacitance information detected by the plurality of capacitance sensors. The grip determination unit determines that the steering handle is being gripped when the detected value of the torque sensor is equal to or greater than the second determination threshold. The steering device is characterized in that the second determination threshold is set to a value smaller than the detected value of the torque sensor when the output values ​​of the plurality of sensor units are the first value.

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