Grasp Judgment System

Abstract

To accurately determine whether a driver is gripping a steering operation device.SOLUTION: A gripping determination system 3 includes: a contact sensor 35 which generates varying electrostatic capacities depending on the contact position of a driver to a steering operation device 22; a steering torque sensor 32 which outputs an output value corresponding to a steering torque; and a controller 15 which determines whether or not the driver is gripping the steering operation device 22, based on the electrostatic capacity of the contact sensor 35 and the output value of the steering torque sensor 32. The controller 15 estimates the contact position of the driver to the steering operation device 22, based on the electrostatic capacity of the contact sensor 35, establishes a threshold value corresponding to the contact position of the driver and determines that the driver is gripping the steering operation device 22 when the output value of the steering torque sensor 32 is equal to or in excess of the threshold value.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a grip determination system for determining whether a driver of a vehicle is gripping a steering operator. [Background technology]

[0002] In recent years, efforts to provide vulnerable transport users with access to sustainable transport systems have become more active. To achieve this, research and development into preventive safety technologies is gaining attention to further improve road safety and convenience.

[0003] In particular, as a development related to preventive safety technology, the development of a grip determination system for determining whether or not a vehicle driver is gripping a steering operator (for example, a steering wheel) has attracted attention. For example, a grip determination system is known that determines that a driver is gripping a steering operator when the output value of a steering torque sensor is equal to or greater than a threshold value (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-82821 Summary of the Invention [Problem to be solved by the invention]

[0005] The output value of the steering torque sensor varies depending on the driver's contact position with the steering operator. In the above-described conventional technology, the threshold value is set depending on whether the driver is in contact with the steering operator, but the threshold value is not set taking into account the driver's contact position with the steering operator. Therefore, if the threshold value is set to a relatively small value, it is likely to be determined that the driver is gripping the steering operator even if the driver is not gripping the steering operator in a portion of the steering operator where the output value of the steering torque sensor is likely to be generated. On the other hand, if the threshold value is set to a relatively large value, it is likely to be determined that the driver is not gripping the steering operator even if the driver is gripping the steering operator in a portion of the steering operator where the output value of the steering torque sensor is unlikely to be generated. As such, in the above-described conventional technology, it is difficult to accurately determine whether the driver is gripping the steering operator depending on the driver's contact position with the steering operator.

[0006] In view of the above background, the present invention aims to accurately determine whether or not a driver is holding a steering operator based on the driver's contact position with the steering operator, and ultimately to contribute to the development of sustainable transportation systems. [Means for solving the problem]

[0007] In order to solve the above problem, one aspect of the present invention is a grip determination system (3) comprising: a contact sensor (35) provided on a steering operator (22) of a vehicle (1) and configured to generate different capacitances depending on the driver's contact position with the steering operator; a steering torque sensor (32) configured to output an output value corresponding to the steering torque generated by the driver's steering operation with respect to the steering operator; and a control device (15) that determines whether the driver is gripping the steering operator based on the capacitance of the contact sensor and the output value of the steering torque sensor, wherein the control device estimates the driver's contact position with respect to the steering operator based on the capacitance of the contact sensor, sets a threshold value corresponding to the estimated driver's contact position, and determines that the driver is gripping the steering operator if the output value of the steering torque sensor is equal to or greater than the threshold value.

[0008] According to this aspect, the threshold value can be set to an appropriate value depending on the driver's contact position with the steering operator. Therefore, it is possible to accurately determine whether the driver is gripping the steering operator, which in turn can contribute to the development of a sustainable transportation system.

[0009] In the above aspect, the steering torque sensor is configured so that the output value is larger when the driver is holding a first part of the steering operator than when the driver is holding a second part of the steering operator, and the control device may set the threshold value to a larger value when it estimates that the driver's contact position with the steering operator is the first part of the steering operator than when it estimates that the driver's contact position with the steering operator is the second part of the steering operator.

[0010] According to this aspect, the threshold value can be set to an appropriate value depending on whether the driver's contact position with the steering operator is in the first part (the part where the output value of the steering torque sensor is likely to be produced) or the second part (the part where the output value of the steering torque sensor is unlikely to be produced).

[0011] In the above aspect, the steering torque sensor is configured so that the output value is larger when the driver is gripping the upper part of the steering operator as the first part than when the driver is gripping the lower part of the steering operator as the second part, and the control device may set the threshold value to a larger value when it estimates that the driver's contact position with the steering operator is the upper part of the steering operator than when it estimates that the driver's contact position with the steering operator is the lower part of the steering operator.

[0012] According to this aspect, the threshold value can be set to an appropriate value depending on whether the driver's contact position with the steering operator is at the upper part of the steering operator (the part where the output value of the steering torque sensor is likely to be produced) or at the lower part of the steering operator (the part where the output value of the steering torque sensor is unlikely to be produced).

[0013] In the above aspect, the vehicle has a steering device (7) that steers the wheels (17), and the steering torque sensor has a rotor (71) connected to the steering operator and rotating around a rotation axis, a sleeve (72) connected to the steering device and arranged on the outer periphery of the rotor, and a torsion bar (73) that connects the rotor and the sleeve, and when the driver is holding the upper part of the steering operator, the rotor is offset more significantly from the sleeve in a direction perpendicular to the rotation axis than when the driver is holding the lower part of the steering operator, thereby increasing the output value of the steering torque sensor.

[0014] According to this aspect, the threshold value can be set to an appropriate value depending on the structural characteristics of the steering torque sensor.

[0015] In the above aspect, the control device may set the threshold to a first value when it estimates that the driver's contact position with the steering operator is the first part of the steering operator, set the threshold to a second value smaller than the first value when it estimates that the driver's contact position with the steering operator is the second part of the steering operator, and set the threshold to a third value smaller than the first value and larger than the second value when it estimates that the driver's contact position with the steering operator is a third part between the first part and the second part of the steering operator.

[0016] According to this aspect, the threshold value can be set more precisely depending on the contact position of the driver with the steering operator, thereby making it possible to more accurately determine whether the driver is gripping the steering operator.

[0017] In the above aspect, the control device is configured to be able to execute automatic driving control of the vehicle, and when a stop condition for stopping the automatic driving control is met while the automatic driving control is being executed, the control device sets the threshold value according to the driver's contact position, and when the output value of the steering torque sensor is equal to or greater than the threshold value, it determines that the driver is holding the steering operator and transfers the authority to drive the vehicle to the driver.

[0018] According to this aspect, it is possible to accurately determine whether the driver is gripping the steering operator, and then transfer the driving authority of the vehicle to the driver. Therefore, it is possible to prevent the driving authority of the vehicle from being transferred to the driver in a state where the driver is not sufficiently gripping the steering operator (for example, a state where an object other than the driver's hand, such as a wet towel, is placed on the steering operator, or a state where only a few of the driver's fingers are on the steering operator).

[0019] In the above aspect, the contact sensor may include a plurality of capacitance sensors (53 to 58), and when the plurality of capacitance sensors include a normal capacitance sensor and a faulty capacitance sensor, the control device may estimate the driver's contact position with the steering operator based on the capacitance of the normal capacitance sensor, set the threshold value according to the estimated driver's contact position, and determine that the driver is holding the steering operator when the output value of the steering torque sensor is equal to or greater than the threshold value.

[0020] According to this aspect, even if some of the multiple capacitance sensors are faulty, it is possible to determine whether the driver is holding the steering operator by using the capacitance of a normal capacitance sensor in combination with the output value of the steering torque sensor.

[0021] In the above aspect, the contact sensor may include a plurality of capacitance sensors (53 to 58), and when the plurality of capacitance sensors include a normal capacitance sensor and a faulty capacitance sensor and the control device cannot estimate the driver's contact position with respect to the steering operator based on the capacitance of the normal capacitance sensor, the control device may estimate that the driver's contact position with respect to the steering operator is a part of the steering operator that corresponds to the faulty capacitance sensor, set the threshold value according to the estimated driver's contact position, and determine that the driver is holding the steering operator when the output value of the steering torque sensor is equal to or greater than the threshold value.

[0022] According to this aspect, even if some of the multiple capacitance sensors fail and the driver's contact position with the steering operator cannot be estimated based on the capacitance of the normal capacitance sensors, the output value of the steering torque sensor can be used to determine whether the driver is holding the steering operator. [Effects of the Invention]

[0023] According to the above aspect, it is possible to accurately determine whether or not the driver is gripping the steering operator, depending on the contact position of the driver with respect to the steering operator. [Brief explanation of the drawings]

[0024] [Figure 1] A functional configuration diagram showing a vehicle to which a grip determination system according to a first embodiment of the present invention is applied. [Figure 2] FIG. 1 is a front view showing a steering wheel according to a first embodiment of the present invention; [Figure 3] FIG. 1 is a perspective view showing a steering torque sensor according to a first embodiment of the present invention; [Figure 4] FIG. 1 is a plan view showing a steering torque sensor according to a first embodiment of the present invention; [Figure 5] 1 is a flowchart showing grip determination control according to a first embodiment of the present invention; [Figure 6] 1 is a flowchart showing threshold setting control according to a first embodiment of the present invention; [Figure 7] 10 is a flowchart showing grip determination control according to a second embodiment of the present invention. [Figure 8] 10 is a flowchart showing first threshold setting control according to a second embodiment of the present invention. [Figure 9] 10 is a flowchart showing second threshold setting control according to a second embodiment of the present invention. [Figure 10] 10 is a flowchart showing a third threshold setting control according to a second embodiment of the present invention. [Figure 11] 10 is a flowchart showing a fourth threshold setting control according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] (First embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

[0026] <Vehicle 1> First, a vehicle 1 to which a grip determination system 3 according to a first embodiment of the present invention is applied will be described with reference to Fig. 1. For example, the vehicle 1 is an automobile. In other embodiments, the vehicle 1 may be a vehicle other than an automobile (for example, a two-wheeled vehicle).

[0027] The vehicle 1 has a drive unit 5, a brake unit 6, a steering unit 7, an HMI (Human Machine Interface) 8, a driving operator 9, a navigation unit 10, an external sensor 11, a vehicle sensor 12, a driver sensor 13, and a control unit 15. Below, the components of the vehicle 1 will be explained in order.

[0028] The drive unit 5 is a device that applies drive force to the vehicle 1. The drive unit 5 includes a drive source that generates drive force for running the vehicle 1. For example, the drive source is configured by an internal combustion engine and / or an electric motor.

[0029] The braking device 6 is a device that applies braking force to the vehicle 1. For example, the braking device 6 includes a brake caliper that presses a pad against a brake rotor, and an electric cylinder that supplies hydraulic pressure to the brake caliper.

[0030] The steering device 7 is a device that changes the steering angle of the wheels 17 by steering the wheels 17. For example, the steering device 7 includes a rack-and-pinion mechanism connected to the wheels 17 and an electric motor that drives the rack-and-pinion mechanism.

[0031] The HMI 8 is a device that presents information to an occupant (e.g., the driver) of the vehicle 1 and accepts information input by the occupant. The HMI 8 includes a touch panel 19 and an audio output device 20. The touch panel 19 displays various screens to the occupant and accepts input operations by the occupant on the various screens. The audio output device 20 outputs audio guidance, warning sounds, etc.

[0032] The driving operators 9 are devices that accept driving operations by the driver. The driving operators 9 include a steering wheel 22 (an example of a steering operator) that accepts steering operations of the vehicle 1 by the driver, an accelerator pedal 23 that accepts acceleration operations of the vehicle 1 by the driver, and a brake pedal 24 that accepts braking operations of the vehicle 1 by the driver. Details of the steering wheel 22 will be described later.

[0033] The navigation device 10 is a device that provides route guidance to the destination of the vehicle 1. The navigation device 10 identifies the current position of the vehicle 1 based on GNSS signals received from artificial satellites. The navigation device 10 sets a route to the destination of the vehicle 1 based on the current position of the vehicle 1 and the destination of the vehicle 1 inputted to the touch panel 19 by the occupant.

[0034] The external sensor 11 is a device that detects the state of the outside world of the vehicle 1. The external sensor 11 includes multiple cameras 26, multiple radars 27, and multiple lidars 28 (LiDAR). Each camera 26 captures images of targets present around the vehicle 1 (surrounding vehicles such as a vehicle ahead, pedestrians, road structures, lane markings, etc.). Each radar 27 emits radio waves such as millimeter waves around the vehicle 1 and captures the reflected waves to detect the positions of targets present around the vehicle 1. Each lidar 28 irradiates light such as infrared light around the vehicle 1 and captures the reflected light to detect the positions of targets present around the vehicle 1.

[0035] The vehicle sensor 12 is a sensor that detects various vehicle conditions. The vehicle sensor 12 includes a vehicle speed sensor 30 that detects the vehicle speed of the vehicle 1, an acceleration sensor 31 that detects the acceleration in the left-right direction (lateral acceleration) of the vehicle 1, and a steering torque sensor 32 that detects the steering torque generated in response to the steering operation of the vehicle 1 by the driver.

[0036] The driver sensor 13 is a device that detects the state of the driver. The driver sensor 13 includes a driver monitor camera 34 and a contact sensor 35. The driver monitor camera 34 captures an image of the driver. The contact sensor 35 is provided on the steering wheel 22 and detects the driver's contact position with respect to the steering wheel 22 based on capacitance. Details of the contact sensor 35 will be described later.

[0037] The control device 15 constitutes a grip determination system 3 together with the vehicle sensor 12 (particularly, the steering torque sensor 32) and the driver sensor 13 (particularly, the contact sensor 35).

[0038] The control device 15 is an electronic control unit (ECU) consisting of a computer configured to execute various processes. The control device 15 includes an arithmetic processing unit (a processor such as a CPU or MPU) and a storage device (memory such as a ROM or RAM). The arithmetic processing unit reads necessary software from the storage device and executes predetermined arithmetic processing in accordance with the read software. The control device 15 may be configured as a single piece of hardware, or may be configured as a unit consisting of multiple pieces of hardware. The control device 15 is connected to each component of the vehicle 1 via a communication network such as a CAN (Controller Area Network), and controls each component of the vehicle 1.

[0039] The control device 15 includes, as functional components, an external environment recognition unit 37, a driving control unit 38, a driving assistance control unit 39, an autonomous driving control unit 40, and a grip determination unit 41. At least some of the functional components of the control device 15 may be realized by hardware such as an LSI, an ASIC, or an FPGA, or may be realized by a combination of software and hardware.

[0040] The external environment recognition unit 37 recognizes the state of the external environment of the vehicle 1 based on the detection results of the external environment sensor 11. For example, the external environment recognition unit 37 recognizes targets (surrounding vehicles such as a vehicle ahead, pedestrians, structures on the road, lane markings, etc.) that exist around the vehicle 1 based on the detection results of the external environment sensor 11.

[0041] The driving control unit 38 controls the driving of the vehicle 1 in response to the driver's driving operation using the driving operator 9. For example, the driving control unit 38 controls the steering device 7 in response to the driver's steering operation of the steering wheel 22 to turn the vehicle 1. The driving control unit 38 controls the drive device 5 in response to the driver's operation of the accelerator pedal 23 to accelerate the vehicle 1, and accelerates the vehicle 1. The driving control unit 38 controls the brake device 6 in response to the driver's operation of the brake pedal 24 to brake the vehicle 1, and decelerates the vehicle 1.

[0042] The driving assistance control unit 39 executes advanced driver assistance control (ADAS: Advanced Driver Assistance Systems) of the vehicle 1 based on the recognition results of the external environment recognition unit 37. The advanced driving assistance control is control equivalent to SAE autonomous driving levels 1 to 2. When the advanced driving assistance control is executed, the driver is the main driver of the vehicle 1 and has the driving authority of the vehicle 1. Hereinafter, the advanced driving assistance control will be abbreviated as "driving assistance control."

[0043] The driving assistance control unit 39 is configured to be able to execute adaptive cruise control (ACC) as driving assistance control. When executing ACC, the driving assistance control unit 39 controls the drive device 5 and the brake device 6 so that the vehicle 1 follows the vehicle ahead while maintaining a predetermined distance therebetween.

[0044] The driving assistance control unit 39 is configured to be able to execute a lane keeping assistance system (LKAS) as driving assistance control. When the LKAS is executed, the driving assistance control unit 39 controls the steering wheel 22 and the steering device 7 to assist the driver in steering the vehicle 1 so that the vehicle 1 maintains its running position within the lane.

[0045] The driving assistance control unit 39 is configured to be able to execute a Collision Mitigation Brake System (CMBS) as driving assistance control. When the CMBS is executed, the driving assistance control unit 39 controls the brake device 6 to mitigate a collision between the vehicle 1 and an object outside the vehicle.

[0046] The autonomous driving control unit 40 executes autonomous driving control (AD: Autonomous Driving) of the vehicle 1. The autonomous driving control is control equivalent to SAE autonomous driving level 3 or higher. When the autonomous driving control is executed, the autonomous driving control unit 40 becomes the main driver of the vehicle 1 and has the authority to drive the vehicle 1. When the autonomous driving control is executed, the autonomous driving control unit 40 automatically controls the drive device 5, the brake device 6, and the steering device 7, and causes the vehicle 1 to travel automatically.

[0047] The grip determination unit 41 determines whether or not the driver is gripping the steering wheel 22 based on the capacitance of the contact sensor 35 and the output value (output voltage) of the steering torque sensor 32. The method of determination will be described in detail later.

[0048] For the sake of convenience, the functional components of the control device 15 will be simply referred to as the "control device 15" below without distinction.

[0049] <Configuration of steering wheel 22> Next, the configuration of the steering wheel 22 will be described with reference to Figure 2. Hereinafter, when simply referred to as "radial direction," it refers to the radial direction of the steering wheel 22, and when simply referred to as "circumferential direction," it refers to the circumferential direction of the steering wheel 22.

[0050] The steering wheel 22 includes a cylindrical hub 43 arranged on the rotation axis A of the steering wheel 22, an annular rim 44 arranged radially outside the hub 43, and a plurality of spokes 45 to 47 extending radially to connect the hub 43 and the rim 44.

[0051] The hub 43 is coupled to a steering shaft (not shown) connected to the steering device 7 so as to be rotatable together with the steering shaft, so that the steering wheel 22 is rotatably supported on the steering shaft.

[0052] The rim 44 is radially spaced apart from the hub 43. In other embodiments, the rim 44 may be directly connected to the hub 43, thereby eliminating the spokes 45-47.

[0053] The multiple spokes 45-47 are spaced apart in the circumferential direction. The multiple spokes 45-47 include a right spoke 45 extending rightward from the hub 43, a left spoke 46 extending leftward from the hub 43, and a lower spoke 47 extending downward from the hub 43. A rectangular right switch unit 49 is provided on the rear surface (the surface facing the driver) of the right spoke 45. For example, the right switch unit 49 includes a switch for starting / ending driving assistance control and a switch for changing the state of driving assistance control (for example, the set vehicle speed of the ACC). A rectangular left switch unit 50 is provided on the rear surface (the surface facing the driver) of the left spoke 46. For example, the left switch unit 50 includes a switch for operating an air conditioning system (not shown) and a switch for operating the navigation device 10.

[0054] <Configuration and Action of Contact Sensor 35> Next, the configuration and operation of the contact sensor 35 will be described with reference to FIG.

[0055] The contact sensor 35 includes a first right-side capacitance sensor 53, a second right-side capacitance sensor 54, a third right-side capacitance sensor 55, a first left-side capacitance sensor 56, a second left-side capacitance sensor 57, and a third left-side capacitance sensor 58. Hereinafter, when there is no need to distinguish between these, they will be referred to as "capacitive sensors 53 to 58."

[0056] Each of the capacitance sensors 53 to 58 is configured with an electrode that can capacitively couple with an object that comes into contact with the steering wheel 22. As the driver's hand comes into contact with the steering wheel 22, the distance between the driver's hand and the electrodes that make up the capacitance sensors 53 to 58 becomes shorter, and the capacitance of the capacitance sensors 53 to 58 increases. The capacitance sensors 53 to 58 are configured to generate different capacitances depending on the contact position of the driver on the steering wheel 22.

[0057] The first right-side capacitance sensor 53 is disposed on the right-side spoke 45. The first right-side capacitance sensor 53 has a first extending portion 61 extending in the left-right direction along the upper edge of the right-side switch unit 49, and a second extending portion 62 bent upward from the left end portion (the radially inner end portion) of the first extending portion 61 and extending along the upper outer periphery of the hub 43.

[0058] The second right-side capacitance sensor 54 is disposed below the first right-side capacitance sensor 53, straddling the right-side spoke 45 and the hub 43. The second right-side capacitance sensor 54 includes an upper extension 65 that extends in the left-right direction along the lower edge of the right-side switch unit 49, and a lower extension 66 that is bent downward from the left end (the radially inner end) of the upper extension 65 and extends along the lower outer periphery of the hub 43.

[0059] The third right-side capacitance sensor 55 is disposed on the right-side spoke 45. The third right-side capacitance sensor 55 extends along the right edge (outer edge) of the right-side switch unit 49.

[0060] The first left capacitance sensor 56 is disposed on the left spoke 46. Like the first right capacitance sensor 53, the first left capacitance sensor 56 includes a first extending portion 61 and a second extending portion 62.

[0061] The second left capacitance sensor 57 is disposed below the first left capacitance sensor 56, straddling the left spoke 46 and the hub 43. Similar to the second right capacitance sensor 54, the second left capacitance sensor 57 includes an upper extension 65 and a lower extension 66.

[0062] The third left capacitance sensor 58 is disposed on the left spoke 46. The third left capacitance sensor 58 extends along the left edge (outer edge) of the left switch unit 50.

[0063] When the driver touches the upper right portion 44R1 and / or the upper left portion 44L1 of the rim 44, the capacitance of the first right capacitance sensor 53 and / or the first left capacitance sensor 56 increases above a reference value. In this case, the control device 15 estimates that the driver's contact position with the steering wheel 22 is the upper portion of the steering wheel 22.

[0064] When the driver touches the lower right portion 44R2 and / or the lower left portion 44L2 of the rim 44, the capacitance of the second right capacitance sensor 54 and / or the second left capacitance sensor 57 increases above the reference value. In this case, the control device 15 estimates that the driver's contact position with the steering wheel 22 is the lower portion of the steering wheel 22.

[0065] When the driver touches the right central portion 44R3 and / or the left central portion 44L3 of the rim 44, the capacitance of the third right capacitance sensor 55 and / or the third left capacitance sensor 58 increases above the reference value. In this case, the control device 15 estimates that the driver's contact position with the steering wheel 22 is the vertical center of the steering wheel 22.

[0066] <Configuration and Operation of Steering Torque Sensor 32> Next, the configuration and operation of the steering torque sensor 32 will be described with reference to FIGS.

[0067] The steering torque sensor 32 has a rotor 71, a sleeve 72 disposed on the outer periphery of the rotor 71, and a torsion bar 73 connecting the rotor 71 and the sleeve 72. Note that the torsion bar 73 is not shown in FIG.

[0068] The rotor 71 is provided so as to be rotatable about the rotation axis X. Hereinafter, the term "axial direction" refers to the direction along the rotation axis X of the rotor 71, and the term "circumferential direction" refers to the circumferential direction centered on the rotation axis X of the rotor 71.

[0069] The rotor 71 is connected to the steering wheel 22. For example, the rotor 71 is provided at the middle of a steering shaft (not shown) that rotatably supports the steering wheel 22. The rotor 71 has a cylindrical shape extending in the axial direction. A plurality of protrusions 75 are provided on the outer circumferential surface of the rotor 71 at intervals in the circumferential direction.

[0070] The sleeve 72 is connected to the steering device 7. The sleeve 72 has a cylindrical shape extending in the axial direction. An annular coil holding portion 77 (only half of which is shown in FIG. 3) is provided on the outer periphery of the sleeve 72. A plurality of coils 78 are held in the coil holding portion 77 at intervals in the axial direction. A plurality of detection windows 79 are provided in the sleeve 72 at intervals in the axial and circumferential directions. The axial positions of the plurality of detection windows 79 correspond to the axial positions of the plurality of coils 78.

[0071] The torsion bar 73 is inserted into the rotor 71. The upper end (one axial end) of the torsion bar 73 is connected to the rotor 71. The lower end (the other axial end) of the torsion bar 73 is connected to the sleeve 72.

[0072] When the steering wheel 22 rotates in response to the driver's steering operation, the rotor 71 connected to the steering wheel 22 rotates. In response, the rotation of the rotor 71 is transmitted to the sleeve 72 via the torsion bar 73, causing the sleeve 72 to rotate. In response, the steering device 7 connected to the sleeve 72 steers the wheels 17, changing the steering angle of the wheels 17.

[0073] As described above, when the rotation of the rotor 71 is transmitted to the sleeve 72 via the torsion bar 73, a torsion corresponding to the steering torque (torque generated in the steering wheel 22 by the steering operation) is generated in the torsion bar 73. This changes the positional relationship between the multiple protrusions 75 of the rotor 71 and the multiple detection windows 79 of the sleeve 72, changing the magnetic flux density of the multiple coils 78, and therefore changing the output value (output voltage) of the steering torque sensor 32. In this way, the steering torque sensor 32 is configured to generate an output value corresponding to the steering torque.

[0074] As shown by the solid line in FIG. 4, when the driver is not gripping the steering wheel 22, the center of the rotor 71 coincides with the center of the sleeve 72. In contrast, when the driver grips the steering wheel 22, a load is applied from the driver's arms to the steering wheel 22. When this load is transmitted from the steering wheel 22 to the rotor 71, as shown by the two-dot chain line in FIG. 4, the rotor 71 is offset relative to the sleeve 72 in a direction perpendicular to the rotation axis X depending on the direction of the load, and the rotor 71 becomes eccentric relative to the sleeve 72. In response to this, the positional relationship between the multiple protrusions 75 of the rotor 71 and the multiple detection windows 79 of the sleeve 72 changes, and the magnetic flux density of the multiple coils 78 changes. Therefore, the output value of the steering torque sensor 32 increases even when no steering torque is generated.

[0075] At this time, the greater the load applied from the driver's arms to the steering wheel 22, the greater the offset width Y of the rotor 71 with respect to the sleeve 72, and the greater the output value of the steering torque sensor 32. When the driver grips the upper part of the steering wheel 22, the driver's hands hold the steering wheel 22 from above, so the weight of the entire driver's arms is likely to be placed on the steering wheel 22. On the other hand, when the driver grips the lower part of the steering wheel 22, the driver's hands are folded and applied to the steering wheel 22 from below, so the weight of the entire driver's arms is less likely to be placed on the steering wheel 22. Therefore, when the driver grips the upper part of the steering wheel 22, the rotor 71 is more offset from the sleeve 72 in the direction perpendicular to the rotation axis X (the offset width Y of the rotor 71 with respect to the sleeve 72 is greater) than when the driver grips the lower part of the steering wheel 22, and the output value of the steering torque sensor 32 is also greater.

[0076] <Grip judgment control> Next, with reference to Fig. 5, a description will be given of grip determination control for determining whether or not the driver is gripping the steering wheel 22. In this embodiment, it is assumed that the control device 15 is executing automatic driving control when the grip determination control starts.

[0077] When the grip determination control is started, the control device 15 determines whether a stop condition for stopping the automatic driving control is met (step ST1). In other words, the control device 15 determines whether the automatic driving level should be shifted from 3 or higher to 2 or lower. For example, the stop condition includes a condition that the driver has performed an operation to stop the automatic driving control on the HMI 8, or a condition that the automatic driving control cannot be continued due to a failure of a sensor or the like. If it is determined that the stop condition is not met (step ST1: No), the control device 15 ends the grip determination control without determining whether the driver is gripping the steering wheel 22.

[0078] When it is determined that the stop condition is met (step ST1: Yes), the control device 15 executes threshold setting control for setting a threshold value T related to the output value of the steering torque sensor 32 (step ST2). The details of the threshold setting control will be described later.

[0079] When the threshold value T is set by the threshold value setting control (step ST2), the control device 15 acquires the output value of the steering torque sensor 32 (step ST3), and determines whether or not the driver is gripping the steering wheel 22 based on the acquired output value of the steering torque sensor 32 and the threshold value T (step ST4). More specifically, when the output value of the steering torque sensor 32 is equal to or greater than the threshold value T, the control device 15 determines that the driver is gripping the steering wheel 22. On the other hand, when the output value of the steering torque sensor 32 is less than the threshold value T, the control device 15 determines that the driver is not gripping the steering wheel 22.

[0080] If it is determined that the driver is gripping the steering wheel 22 (step ST4: Yes), the control device 15 stops the automatic driving control and transfers the driving authority of the vehicle 1 to the driver (step ST5). As a result, the driving subject of the vehicle 1 is transferred from the control device 15 to the driver.

[0081] If it is determined that the driver is not gripping the steering wheel 22 (step ST4: No), the control device 15 executes a gripping prompting process (step ST6). In the gripping prompting process, the control device 15 prompts the driver to grip the steering wheel 22 via the HMI 8.

[0082] <Threshold setting control> Next, the above-mentioned threshold setting control (step ST2) will be described with reference to FIG.

[0083] When the threshold setting control is started, the control device 15 acquires the capacitance of the capacitance sensors 53 to 58 (step ST11), and estimates the driver's contact position with respect to the steering wheel 22 (hereinafter simply referred to as the "contact position") based on the acquired capacitance (step ST12).

[0084] Next, based on the estimation result of step ST12, the control device 15 determines whether the contact position is at the upper part (an example of the first part) of the steering wheel 22 (step ST13). If it is determined that the contact position is at the upper part of the steering wheel 22 (step ST13: Yes), the control device 15 sets the threshold value T to a first value T1 (step ST14).

[0085] If it is determined that the contact position is not the upper part of the steering wheel 22 (step ST13: No), the control device 15 determines whether the contact position is the lower part of the steering wheel 22 (an example of the second part) based on the estimation result of step ST12 (step ST15). If it is determined that the contact position is the lower part of the steering wheel 22 (step ST15: Yes), the control device 15 sets the threshold value T to a second value T2 (step ST16). The second value T2 is smaller than the first value T1.

[0086] If it is determined that the contact position is not the lower part of the steering wheel 22 (step ST15: No), the control device 15 presumes that the driver is contacting the vertical center part (an example of a third part) of the steering wheel 22 (step ST17), and sets the threshold value T to a third value T3 (step ST18). The third value T3 is smaller than the first value T1 and larger than the second value T2.

[0087] <Effects of the first embodiment> The control device 15 estimates the contact position based on the capacitance of the capacitance sensors 53 to 58, and sets the threshold value T according to the estimated contact position. This allows the threshold value T to be set to an appropriate value according to the contact position, making it possible to accurately determine whether the driver is gripping the steering wheel 22.

[0088] Furthermore, when the output value of the steering torque sensor 32 is equal to or greater than the threshold value T, the control device 15 determines that the driver is gripping the steering wheel 22, and transfers the driving authority of the vehicle 1 to the driver. This makes it possible to accurately determine that the driver is gripping the steering wheel 22, and then transfer the driving authority of the vehicle 1 to the driver.

[0089] (Second embodiment) The second embodiment of the present invention will be described below with reference to Figures 7 to 11. Note that the contents other than the grip determination control executed by the control device 15 are the same as those in the first embodiment, and therefore description thereof will be omitted.

[0090] Hereinafter, the three capacitance sensors 53-55 arranged on the right side of the steering wheel 22 will be referred to as right capacitance sensors 53-55, and the three capacitance sensors 56-58 arranged on the left side of the steering wheel 22 will be referred to as left capacitance sensors 56-58. Furthermore, the two capacitance sensors 53, 56 arranged on the upper parts of both the left and right sides of the steering wheel 22 will be referred to as upper capacitance sensors 53, 56, the two capacitance sensors 54, 57 arranged on the lower parts of both the left and right sides of the steering wheel 22 will be referred to as lower capacitance sensors 54, 57, and the two capacitance sensors 55, 58 arranged in the vertical center of both the left and right sides of the steering wheel 22 will be referred to as center capacitance sensors 55, 58.

[0091] <Grip judgment control> When the grip determination control is started, the control device 15 determines whether or not some of the capacitance sensors 53 to 58 have failed (step ST21). If it is determined that some of the capacitance sensors 53 to 58 have not failed (step ST21: No), the control device 15 ends the grip determination control without determining whether or not the driver is gripping the steering wheel 22.

[0092] If it is determined that some of the capacitance sensors 53 to 58 are faulty (step ST21: Yes), the control device 15 determines whether either the right capacitance sensors 53 to 55 or the left capacitance sensors 56 to 58 are normal (step ST22).

[0093] When it is determined that either the right capacitance sensors 53 to 55 or the left capacitance sensors 56 to 58 are normal (step ST22: Yes), the control device 15 executes first threshold setting control (step ST23). The details of the first threshold setting control will be described later.

[0094] If it is determined that neither the right capacitance sensors 53-55 nor the left capacitance sensors 56-58 are normal (step ST22: No), the control device 15 determines whether the lower capacitance sensors 54, 57 and the central capacitance sensors 55, 58 are normal (step ST24).

[0095] If it is determined that the lower capacitance sensors 54, 57 and the central capacitance sensors 55, 58 are normal (step ST24: Yes), the control device 15 executes second threshold setting control (step ST25). The second threshold setting control will be described in detail later.

[0096] If it is determined that at least one of the lower capacitance sensors 54, 57 or the central capacitance sensors 55, 58 is not normal (step ST24: No), the control device 15 determines whether the upper capacitance sensors 53, 56 and the lower capacitance sensors 54, 57 are normal (step ST26).

[0097] If it is determined that the upper capacitance sensors 53, 56 and the lower capacitance sensors 54, 57 are normal (step ST26: Yes), the control device 15 executes third threshold setting control (step ST27). Details of the third threshold setting control will be described later.

[0098] If it is determined that at least one of the upper capacitance sensors 53, 56 or the lower capacitance sensors 54, 57 is not normal (step ST26: No), the control device 15 determines whether the upper capacitance sensors 53, 56 and the central capacitance sensors 55, 58 are normal (step ST28).

[0099] If it is determined that the upper capacitance sensors 53, 56 and the central capacitance sensors 55, 58 are normal (step ST28: Yes), the control device 15 executes fourth threshold setting control (step ST29). The details of the fourth threshold setting control will be described later.

[0100] If it is determined that at least one of the upper capacitance sensors 53, 56 or the central capacitance sensors 55, 58 is not normal (step ST28: No), the control device 15 terminates the grip determination control without determining whether the driver is gripping the steering wheel 22.

[0101] When the threshold value T is set by the first threshold value setting control (step ST23), the second threshold value setting control (step ST25), the third threshold value setting control (step ST27), or the fourth threshold value setting control (step ST29), the control device 15 acquires the output value of the steering torque sensor 32 (step ST30).

[0102] Next, the control device 15 executes a grip determination process (step ST31). In the grip determination process, the control device 15 determines whether the driver is gripping the steering wheel 22 based on the output value of the steering torque sensor 32 and the threshold value T. More specifically, when the output value of the steering torque sensor 32 is equal to or greater than the threshold value T, the control device 15 determines that the driver is gripping the steering wheel 22. On the other hand, when the output value of the steering torque sensor 32 is less than the threshold value T, the control device 15 determines that the driver is not gripping the steering wheel 22.

[0103] <First threshold setting control> Next, the above-mentioned first threshold setting control (step ST23) will be described with reference to Fig. 8. Note that steps ST43 to ST48 of the first threshold setting control are similar to steps ST13 to ST18 of the threshold setting control in the first embodiment, and therefore description thereof will be omitted.

[0104] When the first threshold setting control is started, the control device 15 acquires the capacitance of the normal capacitance sensors 53-58 (here, either the right capacitance sensors 53-55 or the left capacitance sensors 56-58) (step ST41). Next, the control device 15 estimates the contact position of the driver with respect to the steering wheel 22 (hereinafter simply referred to as the "contact position") based on the capacitance of the normal capacitance sensors 53-58 acquired in step ST41 (step ST42).

[0105] <Second threshold setting control> Next, the above-mentioned second threshold setting control (step ST25) will be described with reference to Fig. 9. Note that steps ST55 to ST58 of the second threshold setting control are similar to steps ST15 to ST18 of the threshold setting control in the first embodiment, and therefore description thereof will be omitted.

[0106] When the second threshold setting control is started, the control device 15 acquires the capacitances of the normal capacitance sensors 53 to 58 (here, the lower capacitance sensors 54, 57 and the central capacitance sensors 55, 58) (step ST51). Next, the control device 15 estimates the contact position based on the capacitances of the normal capacitance sensors 53 to 58 acquired in step ST51 (step ST52).

[0107] Next, the control device 15 determines whether or not the contact position could be estimated based on the capacitance of the normal capacitance sensors 53-58 (step ST53). If it is determined that the contact position could not be estimated based on the capacitance of the normal capacitance sensors 53-58 (step ST53: No), the control device 15 estimates that the contact position is at the upper part of the steering wheel 22, and sets the threshold value T to a first value T1 (step ST54). In this way, the control device 15 estimates that the contact position is at a part corresponding to the faulty capacitance sensor 53-58 (here, the upper capacitance sensors 53, 56), and sets the threshold value T according to the estimated contact position.

[0108] <Third threshold setting control> Next, the above-mentioned third threshold setting control (step ST27) will be described with reference to Fig. 10. Note that steps ST63 to ST66 of the third threshold setting control are similar to steps ST13 to ST16 of the threshold setting control in the first embodiment, and therefore description thereof will be omitted.

[0109] When the third threshold setting control is started, the control device 15 acquires the capacitances of the normal capacitance sensors 53 to 58 (here, the upper capacitance sensors 53, 56 and the lower capacitance sensors 54, 57) (step ST61). Next, the control device 15 estimates the contact position based on the capacitances of the normal capacitance sensors 53 to 58 acquired in step ST61 (step ST62).

[0110] In step ST67, the control device 15 determines that the contact position could not be estimated based on the capacitance of the normal capacitance sensors 53 to 58. In this case, the control device 15 estimates that the contact position is in the vertical center of the steering wheel 22, and sets the threshold value T to a third value T3 (step ST68). In this way, the control device 15 estimates that the contact position is in the part corresponding to the faulty capacitance sensor 53 to 58 (here, the central capacitance sensors 55, 58), and sets the threshold value T according to the estimated contact position.

[0111] <Fourth threshold setting control> Next, the above-mentioned fourth threshold setting control (step ST29) will be described with reference to Fig. 11. Note that steps ST73 to ST74 and ST77 to ST78 of the fourth threshold setting control are similar to steps ST13 to ST14 and ST17 to ST18 of the threshold setting control in the first embodiment, and therefore description thereof will be omitted.

[0112] When the fourth threshold setting control is started, the control device 15 acquires the capacitances of the normal capacitance sensors 53 to 58 (here, the upper capacitance sensors 53, 56 and the central capacitance sensors 55, 58) (step ST71). Next, the control device 15 estimates the contact position based on the capacitances of the normal capacitance sensors 53 to 58 acquired in step ST71 (step ST72).

[0113] In step ST75, the control device 15 determines whether or not the contact position could be estimated based on the capacitance of the normal capacitance sensors 53 to 58. If it is determined that the contact position could not be estimated based on the capacitance of the normal capacitance sensors 53 to 58 (step ST75: No), the control device 15 estimates that the contact position is at the lower part of the steering wheel 22, and sets the threshold value T to a second value T2 (step ST76). In this way, the control device 15 estimates that the contact position is at a part corresponding to the faulty capacitance sensor 53 to 58 (here, the lower capacitance sensors 54, 57), and sets the threshold value T according to the estimated contact position.

[0114] <Effects of the second embodiment> In the above-described first threshold setting control, the control device 15 estimates the contact position based on the capacitance of the normal capacitance sensors 53 to 58, and sets the threshold T according to the estimated contact position. As a result, even if some of the capacitance sensors 53 to 58 are faulty, it is possible to determine whether the driver is gripping the steering wheel 22 by using the capacitance of the normal capacitance sensors 53 to 58 in combination with the output value of the steering torque sensor 32.

[0115] Furthermore, in the second to fourth threshold setting controls, when the contact position cannot be estimated based on the capacitance of the normal capacitance sensors 53 to 58, the control device 15 estimates that the contact position is at a part of the steering wheel 22 that corresponds to the faulty capacitance sensor 53 to 58, and sets the threshold T according to the estimated contact position. As a result, even when one of the capacitance sensors 53 to 58 has failed and the contact position of the driver on the steering wheel 22 cannot be estimated based on the capacitance of the normal capacitance sensors 53 to 58, it is possible to determine whether the driver is gripping the steering wheel 22 by using the output value of the steering torque sensor 32.

[0116] <Modification> In the above embodiment, the upper part of the steering wheel 22 is an example of the first part of the steering wheel 22, and the lower part of the steering wheel 22 is an example of the second part of the steering wheel 22. On the other hand, in other embodiments, if the configuration of the steering torque sensor 32 is different from that of the present embodiment, a part other than the upper part of the steering wheel 22 may be the first part of the steering wheel 22, and a part other than the lower part of the steering wheel 22 may be the second part of the steering wheel 22.

[0117] In the above embodiment, the contact sensor 35 includes three capacitance sensors 53-58 on each of the right and left sides of the steering wheel 22. In other embodiments, the contact sensor 35 may include one or two capacitance sensors on each of the right and left sides of the steering wheel 22, or may include four or more capacitance sensors on each of the right and left sides of the steering wheel 22. For example, the first right capacitance sensor 53 and the third right capacitance sensor 55 may be integrated, and the first left capacitance sensor 56 and the third left capacitance sensor 58 may be integrated, so that the contact sensor 35 includes two capacitance sensors on each of the right and left sides of the steering wheel 22.

[0118] In the above embodiment, the contact sensor 35 includes capacitance sensors 53 to 58 on the hub 43, the right spoke 45, and the left spoke 46 of the steering wheel 22. In other embodiments, the contact sensor 35 may include capacitance sensors on the rim 44 of the steering wheel 22.

[0119] In the above embodiment, the steering wheel 22 having the annular rim 44 is used as the steering operator. In other embodiments, an operator (e.g., a control stick) that does not have the annular rim 44 may be used as the steering operator.

[0120] Although the description of the specific embodiment has been completed above, the present invention is not limited to the above embodiment and its modifications, and can be modified in a wide range of ways. [Explanation of symbols]

[0121] 1: Vehicle 3: Grasp judgment system 7: Steering device 15: Control device 17:Wheel 22: Steering wheel (an example of a steering control) 32: Steering torque sensor 35: Contact sensor 53: First right capacitive sensor 54: Second right capacitive sensor 55: Third right capacitive sensor 56: 1st left capacitive sensor 57: Second left capacitive sensor 58: Third left capacitive sensor 71: Rotor 72: Sleeve 73: Torsion bar T: threshold T1: First value T2: Second value T3: The third value X: Rotation axis

Claims

1. a contact sensor provided on a steering operator of a vehicle, the contact sensor being configured to generate different capacitances depending on a contact position of a driver on the steering operator; a steering torque sensor configured to output an output value corresponding to a steering torque generated by a steering operation of the steering operator by a driver; a control device that determines whether a driver is gripping the steering operator based on the capacitance of the contact sensor and an output value of the steering torque sensor, The control device estimating a contact position of the driver with respect to the steering operator based on the capacitance of the contact sensor; A threshold value is set according to the estimated driver's contact position. A grip determination system that determines that the driver is gripping the steering operator when the output value of the steering torque sensor is equal to or greater than the threshold value.

2. the steering torque sensor is configured to have an output value that is larger when the driver is gripping a first portion of the steering operator than when the driver is gripping a second portion of the steering operator, The grip determination system of claim 1, wherein the control device sets the threshold value to a larger value when it estimates that the driver's contact position with the steering operator is the first part of the steering operator than when it estimates that the driver's contact position with the steering operator is the second part of the steering operator.

3. the steering torque sensor is configured so that an output value is larger when the driver is gripping an upper portion of the steering operator as the first portion than when the driver is gripping a lower portion of the steering operator as the second portion, The grip determination system described in claim 2, wherein the control device sets the threshold value to a larger value when it estimates that the driver's contact position with the steering operator is at the upper part of the steering operator than when it estimates that the driver's contact position with the steering operator is at the lower part of the steering operator.

4. the vehicle has a steering device that steers wheels, The steering torque sensor a rotor connected to the steering operator and rotating about a rotation axis; a sleeve connected to the steering device and disposed on an outer periphery of the rotor; a torsion bar connecting the rotor and the sleeve, The grip determination system of claim 3, wherein when the driver is gripping the upper part of the steering operator, the rotor is offset more significantly relative to the sleeve in a direction perpendicular to the rotation axis than when the driver is gripping the lower part of the steering operator, thereby increasing the output value of the steering torque sensor.

5. The control device setting the threshold to a first value when it is estimated that the contact position of the driver with respect to the steering operator is the first portion of the steering operator; when it is estimated that the contact position of the driver with respect to the steering operator is the second portion of the steering operator, the threshold value is set to a second value smaller than the first value; A grip determination system as described in claim 2, wherein when it is estimated that the driver's contact position with the steering operator is a third part between the first part and the second part of the steering operator, the threshold value is set to a third value smaller than the first value and larger than the second value.

6. The control device The vehicle is provided so as to be capable of executing automatic driving control, When a stop condition for stopping the automatic driving control is met during execution of the automatic driving control, the threshold value is set according to a contact position of the driver; A grip determination system as described in any one of claims 1 to 5, which determines that the driver is gripping the steering operator when the output value of the steering torque sensor is greater than or equal to the threshold value, and transfers driving authority of the vehicle to the driver.

7. the contact sensor includes a plurality of capacitance sensors; The control device When the plurality of capacitance sensors includes a normal capacitance sensor and a faulty capacitance sensor, a contact position of the driver with respect to the steering operator is estimated based on the capacitance of the normal capacitance sensor; setting the threshold value according to the estimated contact position of the driver; 6. The grip determination system according to claim 1, wherein the system determines that the driver is gripping the steering operator when the output value of the steering torque sensor is equal to or greater than the threshold value.

8. the contact sensor includes a plurality of capacitance sensors; The control device When the plurality of capacitance sensors include a normal capacitance sensor and a faulty capacitance sensor and the contact position of the driver with respect to the steering operator cannot be estimated based on the capacitance of the normal capacitance sensor, it is estimated that the contact position of the driver with respect to the steering operator is a part of the steering operator that corresponds to the faulty capacitance sensor, setting the threshold value according to the estimated contact position of the driver; 6. The grip determination system according to claim 1, wherein the system determines that the driver is gripping the steering operator when the output value of the steering torque sensor is equal to or greater than the threshold value.

Images