Steering system

Abstract

There was a need for technology that could accurately determine whether the driver's attention was sufficient while driving an autonomous vehicle. [Solution] The steering device comprises a gripping unit, an output unit, and a control unit. The gripping unit includes a first acquisition unit that acquires capacitance generated when a conductor approaches the gripping unit. The control unit performs a determination control that determines the determination result based on the amount of change in capacitance during the sampling period to either a hold determination, indicating that the gripping unit is being held by the driver, or a non-hold determination, indicating that the gripping unit is not being held by the driver. The output unit outputs the determination result. The non-hold determination is determined when the non-hold condition is met, and the non-hold condition includes a first condition, where the amount of change is smaller than a predetermined reference amount of change, and a second condition, where this condition is met over a reference time longer than the sampling period.

Description

Technical Field

[0001] The present disclosure relates to a steering device.

Background Art

[0002] In Patent Document 1, a technique for suppressing a decrease in a driver's attention to driving in autonomous driving is disclosed. During autonomous driving, it may be permissible for the driver to remove their hands from the steering wheel. If the state in which the driver has removed their hands from the steering wheel continues for a long time, the driver's attention to driving may gradually decrease. Therefore, the technique of Patent Document 1 periodically issues a notification for preventing a decrease in the attention of a driver who has removed their hands from the steering wheel. The notification is a notification prompting the driver to hold the steering wheel or a notification prompting the driver to check the surroundings of the vehicle.

[0003] The notification for preventing a decrease in the driver's attention is issued based on the elapsed time since the state in which the driver has removed their hands from the steering wheel has started in autonomous driving. The notification is issued to the driver when the elapsed time exceeds a certain time. After that, if the driver continues to hold the steering wheel for more than the certain time, the notification ends. Further, at that time, the elapsed time is reset. The reset elapsed time starts to be measured again from zero. When the elapsed time exceeds the certain time again, the notification is issued to the driver. Therefore, the technique of Patent Document 1 can suppress a decrease in the driver's attention to driving in autonomous driving.

[0004] In the technology described in Patent Document 1, the determination of whether or not the driver has taken their hands off the steering wheel is made based on information obtained by a touch sensor installed on the steering wheel. Although Patent Document 1 does not describe a specific touch sensor, generally, a capacitive touch sensor is used for touch sensors installed on steering wheels. A capacitive touch sensor acquires capacitance generated when a hand approaches. When a capacitive touch sensor is installed on a steering wheel, one electrode of the capacitive touch sensor is installed inside the steering wheel. The other electrode of the capacitive touch sensor is a conductor that approaches the surface of the steering wheel. That is, the capacitance of the capacitive touch sensor changes as the conductor approaches the surface of the steering wheel. For example, it is determined whether or not a hand is touching the steering wheel based on the magnitude of this capacitance. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-12356 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The technology described in Patent Document 1 sometimes makes it difficult to accurately determine whether the driver is paying sufficient attention to driving. For example, if a vehicle occupant places a wet towel on the steering wheel, the wet towel acts as a conductor, changing the capacitance obtained. Therefore, even if a conductor other than a person is touching the steering wheel, it is determined that the driver is paying sufficient attention to driving. Thus, there has been a need for technology that can accurately determine whether the driver is paying sufficient attention to driving in an autonomous driving environment. [Means for solving the problem]

[0007] This disclosure can be implemented in the following forms:

[0008] (1) According to one embodiment of the present disclosure, a steering device for a vehicle is provided. The steering device for a vehicle includes a gripping portion to be gripped by the driver of the vehicle, an output portion to output information, and a control portion to control the steering device, wherein the gripping portion includes a first acquisition portion to acquire capacitance generated when a conductor approaches the gripping portion, and the control portion performs a determination control to determine a determination result based on the amount of change of the capacitance during the sampling period obtained from the capacitance acquired by the first acquisition portion at a predetermined sampling period, to determine a hold determination indicating that the gripping portion is being held by the driver, or a non-hold determination indicating that the gripping portion is not being held by the driver, and the output portion outputs the determination result, wherein the non-hold determination is determined when the non-hold condition is met, and the non-hold condition includes a first condition that the amount of change is smaller than a predetermined reference amount of change, and a second condition that is met over a reference time longer than the sampling period. In this embodiment, the non-holding condition is met when the change in capacitance is smaller than the reference change over a reference time. When the driver is holding the grip, the capacitance acquired by the first acquisition unit is likely to fluctuate due to the driver's movement. However, when a conductor other than a person is touching the grip, the capacitance is unlikely to fluctuate as it is when the driver is holding the grip. Therefore, if the change in capacitance is smaller than the reference change, and that change in capacitance continues over a reference time, it is highly likely that the capacitance is generated by a conductor other than a person. In other words, when the non-holding condition, including the first and second conditions, is met, it is unlikely that the driver is holding the grip. This allows the steering device to determine whether or not the driver is holding the grip. When the driver is holding the grip, it is highly likely that the driver is paying attention to driving. Therefore, by determining whether or not the driver is holding the grip, the steering device can accurately determine whether or not the driver is paying sufficient attention to driving. (2) In the steering device of the above form, the control unit may further execute the determination control if the acquired capacitance is greater than a predetermined reference capacitance before executing the determination control during the sampling period, and if the acquired capacitance is less than the reference capacitance before executing the determination control during the sampling period, the determination result may be determined to be the non-hold determination regardless of the first and second conditions. In this embodiment, a non-holding determination is output based on the magnitude of the capacitance acquired by the first acquisition unit. The capacitance acquired by the first acquisition unit is generated by the approach of a conductor. Therefore, if the gripping unit is not being held by the driver, the capacitance acquired by the first acquisition unit is likely to be smaller than the reference capacitance. Accordingly, the steering device determines the determination result to be a non-holding determination when the capacitance is smaller than the reference capacitance. This allows the steering device to suppress the possibility of erroneous determinations occurring in the determination control when there is a possibility that the gripping unit is not being held. (3) In the steering device of the above form, the reference time may be in the range of 9 minutes to 11 minutes, and the reference change amount may be in the range of 2.7 pF to 3.3 pF. (4) In the steering device of the above form, the steering device further includes a second acquisition unit that acquires vehicle operation information representing the operation of the vehicle by the driver, and the control unit may further determine the determination result to hold determination regardless of the first and second conditions if a third condition is met, that the vehicle operation information has been acquired by the second acquisition unit, before executing the determination control during the sampling period. In this embodiment, when vehicle operation information is acquired, there is a high probability that the driver is consciously operating the vehicle. Therefore, the steering system can more accurately determine whether the driver has sufficient attention to driving by performing judgment control based on the vehicle operation information. (5) In the steering device of the above form, the second acquisition unit may acquire the vehicle operation information generated by being operated by the driver's hand holding the gripping unit. In this embodiment, the second acquisition unit acquires vehicle operation information generated by the driver's hand, which is holding the grip. Therefore, when vehicle operation information is acquired, the driver is holding the grip. Thus, the steering device can more accurately determine whether the driver is paying sufficient attention to driving than in an embodiment where vehicle operation information is acquired by an operation other than the hand. (6) In the steering device of the above form, the second acquisition unit acquires the vehicle operation information generated by being operated by the driver's foot, and the non-retention condition may further include a fourth condition that the third condition is not met before the first condition. In this configuration, for the non-retention condition to be met, conditions related to two pieces of information—the change in capacitance and vehicle operation information—must be satisfied. Foot movements during driving are simpler than hand movements. Therefore, it is more difficult to determine whether the driver is paying sufficient attention to driving based on vehicle operation information obtained through foot movements than through hand movements. However, even when vehicle operation information is obtained through foot movements, the steering system can accurately determine whether the driver is paying sufficient attention to driving by using both pieces of information. [Brief explanation of the drawing]

[0009] [Figure 1] An explanatory diagram showing the steering system. [Figure 2] An explanatory diagram showing the gripping part and rotating part of the first embodiment. [Figure 3] A graph showing the change in capacitance when a person is holding the gripping part. [Figure 4] A graph showing the change in capacitance when a wet towel is wrapped around something. [Figure 5] A flowchart illustrating the control of the first embodiment. [Figure 6] A flowchart illustrating the control of the second embodiment. [Figure 7] An explanatory diagram showing the gripping and rotating parts of the third embodiment. [Figure 8] A flowchart illustrating the control of the third embodiment. [Figure 9] A flowchart illustrating the control of the fourth embodiment. [Modes for carrying out the invention]

[0010] A. First Embodiment: A-1. Device Configuration: FIG. 1 is an explanatory diagram showing a steering device 100. The steering device 100 changes the traveling direction of a vehicle M. The vehicle M is configured to be capable of performing both automatic driving and manual driving. The steering device 100 is operated by a driver DR to change the traveling direction of the vehicle M during manual driving of the vehicle M. Note that automatic driving is a driving that does not require the operation of the driver DR. During automatic driving, the driver DR is allowed to release their hand from a gripping portion 110, which will be described later. The switching from automatic driving to manual driving will be described later.

[0011] The steering device 100 is connected to a rotation axis AR of the vehicle M and is configured to be rotatable about an axis AX of the rotation axis AR. The rotation of the steering device 100 is transmitted to a steering gear box (not shown) via the rotation axis AR. The direction along the axis AX of the rotation axis AR is denoted as the X direction in FIG. 1. The direction away from the driver DR is denoted as the +X direction. Among the directions orthogonal to the axis AX, the direction along the left-right direction of the vehicle M is denoted as the Y direction. The direction along the direction toward the right direction of the vehicle M is denoted as the +Y direction, and the direction along the direction toward the left direction is denoted as the -Y direction. The direction orthogonal to the axis AX and the Y direction is denoted as the Z direction. Also, in FIG. 1, the vertical direction is represented by an MU axis. The upward direction in the vertical direction is the positive direction of the MU axis. The direction of the traveling direction of the vehicle M is an axis orthogonal to the MU axis and is represented by an MF axis.

[0012] The steering device 100 includes a rotating portion 120, a gripping portion 110, an output portion 130, and a control portion 140.

[0013] FIG. 2 is an explanatory diagram showing the gripping portion 110 and the rotating portion 120 of the first embodiment. The rotating portion 120 is rotatably attached to the vehicle M. The rotating portion 120 is connected to the gripping portion 110. The rotating portion 120 rotates by the operation of the driver DR via the gripping portion 110. The direction of the wheels of the vehicle M changes by changing the rotation direction and the rotation angle of the rotating portion 120. Thereby, the traveling direction of the vehicle M is changed.

[0014] The rotating part 120 includes a hub part 121 and a spoke part 122. The hub part 121 is connected to the rotation axis AR of the steering device 100. The spoke part 122 is a plurality of struts that connect the hub part 121 and the gripping part 110 by extending radially from the hub part 121 to the gripping part 110.

[0015] The gripping part 110 is a part that is gripped by the driver DR of the vehicle M. That is, the gripping part 110 is a part that the driver DR holds to rotate the rotating part 120 during manual driving. The gripping part 110 has an annular outer shape that extends along the rotation direction of the rotating part 120. For this reason, the gripping part 110 is provided so as to surround the hub part 121. The gripping part 110 is connected to the hub part 121 via the spoke part 122 which is a plurality of struts. For this reason, a plurality of spaces S exist between the hub part 121 and the gripping part 110. The driver DR can easily grip the gripping part 110 by passing a finger through the space S. Furthermore, the gripping part 110 includes a first acquisition part 111.

[0016] The first acquisition part 111 acquires the capacitance generated when a conductor approaches the gripping part 110. Specifically, the first acquisition part 111 is a capacitive touch sensor. The first acquisition part 111 includes electrodes provided inside the gripping part 110 along the shape of the gripping part 110. That is, the electrodes of the first acquisition part 111 are covered by the outer skin of the gripping part 110. The first acquisition part 111 acquires the capacitance generated by the electrodes inside the gripping part 110 and a conductor approaching the outer skin of the gripping part 110. For example, when the driver DR holds the gripping part 110, the first acquisition part 111 acquires a larger capacitance than when the driver DR is not holding the gripping part 110.

[0017] The output unit 130 shown in Figure 1 outputs information. The output unit 130 is, for example, an interface for connecting to the LIN (Local Interconnect Network) connected to the control device of the vehicle M. More specifically, the output unit 130 receives information from the control unit 140 indicating whether or not the gripping unit 110 is being held by the driver DR. The output unit 130 transmits this information to the control device of the vehicle M. Hereafter, the information indicating whether or not the gripping unit 110 is being held by the driver DR will also be referred to as the "determination result".

[0018] The control unit 140 controls the steering device 100. The control unit 140 is configured as a logic circuit centered on a microcomputer. More specifically, the control unit 140 includes a processor, RAM, and ROM. The processor executes a pre-set control program. The ROM stores control programs and control data necessary for the CPU to perform various calculations. The RAM is used to temporarily read and write various data necessary for the processor to perform various calculations. The functions of the control unit 140 are described below.

[0019] A-2. Non-retention conditions: When switching from automated driving to manual driving, it is necessary that the driver (DR) has sufficient attention to driving. The control unit 140 determines whether the driver (DR) has sufficient attention to driving by determining whether the driver (DR) is holding the gripping part 110. Specifically, the state in which the driver (DR) is holding the gripping part 110 means that the driver (DR) is gripping the gripping part 110 to the extent that they can control the direction of travel of the vehicle M. In this state, when switching from automated driving to manual driving, the driver (DR) can smoothly start manual driving.

[0020] The control unit 140 performs a determination control to determine whether or not the gripping unit 110 is being held by the driver DR. The determination control determines the determination result to be either a holding determination, indicating that the gripping unit 110 is being held by the driver DR, or a non-holding determination, indicating that the gripping unit 110 is not being held by the driver DR. The determination control is performed based on the amount of change in capacitance during the sampling period, which is obtained from the capacitance acquired by the first acquisition unit 111 at a predetermined sampling period.

[0021] A non-retention determination is made when the non-retention conditions are met. Conversely, a retention determination is made when the non-retention conditions are not met. The non-retention conditions include multiple load conditions. In the first embodiment, the non-retention conditions include a first condition and a second condition.

[0022] The first condition is that the change in capacitance is smaller than a predetermined reference change. The first condition will be explained below.

[0023] The control unit 140 determines whether the gripping part 110 is being held by the driver DR based on the change in capacitance. The control unit 140 acquires capacitance at a predetermined sampling period using the first acquisition unit 111. The predetermined sampling period is shorter than the capacitance fluctuation that occurs in the first acquisition unit 111. The capacitance fluctuation that occurs in the first acquisition unit 111 is caused by a change in how the driver DR grips the gripping part 110 when the gripping part 110 is being held by the driver DR. Furthermore, the predetermined sampling period will be simply referred to as the "sampling period" below. The sampling period is, for example, approximately 90 msec. The sampling period is set in advance when the steering device 100 is manufactured.

[0024] Figure 3 is a graph showing the change in capacitance when a person is holding the gripping part 110. The control unit 140 determines the change in capacitance during the sampling period based on the acquired capacitance. Figure 3 shows the change in capacitance obtained when vehicle M is driving on a stable circular road. This evaluation was conducted with five subjects, including both men and women. Figure 3 shows the results obtained from the driving of one of the five subjects. In Figure 3, the vertical axis is the change in capacitance, and the horizontal axis is the number of samples. This evaluation was conducted after instructing the subject, the driver DR, to consciously continue to grip the gripping part 110 in the same way. As a result, the evaluation obtains the change in capacitance when the driver DR has sufficient attention to driving. Furthermore, since the evaluation was conducted on a stable circular road, the change in capacitance obtained from the evaluation tends to be smaller than the change in capacitance obtained from actual manual driving. In Figure 3, a change in capacitance of about 3 pF is continuously occurring. That is, in actual manual driving, it is highly likely that a change in capacitance of 3 pF or more will be obtained. Furthermore, the results obtained from other subjects' driving were similar. In the following, the change amount based on the change in capacitance when the gripping part 110 is held by the driver DR, such as 3pF, will be referred to as the "reference change amount".

[0025] The capacitance acquired by the first acquisition unit 111 is generated when a conductor approaches the gripping unit 110. Therefore, capacitance can also be generated when a conductor other than a hand approaches. In the evaluation in Figure 3, the first acquisition unit 111 acquired a capacitance of approximately 20 pF, although this is not shown in Figure 3. A conductor other than a hand that can cause the first acquisition unit 111 to acquire a capacitance of approximately 20 pF is, for example, a wet towel. That is, during automatic driving, if the driver DR wraps a wet towel around the gripping unit 110, a capacitance equivalent to the capacitance when the driver DR is holding the gripping unit 110 may be generated. This wet towel is wrapped around the gripping unit 110 so that it passes through the space S between the hub unit 121 and the gripping unit 110. The wet towel is conductive. Furthermore, depending on the area of ​​the wet towel, it may have an area about the size of a human palm. In the following section, we will describe the evaluation when a wet towel is wrapped around the gripping part 110 so that the first acquisition part 111 acquires a capacitance of approximately 20 pF.

[0026] Figure 4 is a graph showing the change in capacitance when a wet towel is wrapped around it. The control unit 140 determines the change in capacitance in Figure 4 based on the capacitance acquired with the same sampling period as in Figure 3. As shown in Figure 4, the change in capacitance when a wet towel is wrapped around it is less than 1 pF. In other words, the change in capacitance when a wet towel is wrapped around it is smaller than the change in capacitance when the gripping part 110 is held.

[0027] Therefore, if the change in capacitance is less than 3 pF, there is a high probability that the gripping part 110 is not being held by the driver DR. Accordingly, the first condition is set so that the change in capacitance is less than a predetermined reference change.

[0028] The second condition is that the first condition is met over a reference time longer than the sampling period. The second condition will be explained below.

[0029] The first condition can also be satisfied, for example, by the driver DR temporarily touching the gripping part 110. When the driver DR is temporarily touching the gripping part 110, it is unlikely that the driver DR is consciously holding the gripping part 110. For this reason, the non-holding condition requires that the first condition be satisfied for a certain period of time. Specifically, one of the non-holding conditions is defined as the amount of change in capacitance being greater than the reference change over a reference time longer than the sampling period.

[0030] The reference time is determined experimentally. For example, the reference time is 10 minutes. This 10-minute reference time was obtained from evaluations by 10 male and female subjects. The 10-minute reference time is the time required for the change in capacitance to reach the reference change in all subjects' evaluations. During this evaluation, the subjects held the grip 110 in the driver's seat of a stationary vehicle M in a relaxed state. This was instructed to the subjects in order to minimize the change in capacitance. In actual manual driving, the driver DR is likely to frequently change the grip pressure of the grip 110 for driving purposes. In other words, in actual manual driving, the change in capacitance is likely to exceed the reference change in a shorter time than the reference time obtained from this evaluation.

[0031] Therefore, if the change in capacitance over the reference time is smaller than the reference change, the possibility of the gripping portion 110 being held by the driver DR is low. Thus, the second condition is set to satisfy the first condition over the reference time.

[0032] Based on the above, when the non-holding conditions, including the first and second conditions, are met, there is a high probability that the gripping part 110 is not being held by the driver DR. Therefore, when the non-holding conditions are met, the control unit 140 determines the judgment result to be a non-holding judgment. That is, the control unit 140 processes the case assuming that the gripping part 110 is not being held by the driver DR. When the non-holding conditions are not met, the control unit 140 determines the judgment result to be a holding judgment. That is, the control unit 140 processes the case assuming that the gripping part 110 is being held by the driver DR. When the driver DR is holding the gripping part 110, there is a high probability that the driver DR is paying attention to driving. Therefore, by determining whether or not the gripping part 110 is being held by the driver DR, the control unit 140 determines whether or not the driver DR has sufficient attention to driving.

[0033] A-3. Control details: Figure 5 is a flowchart showing the control of the first embodiment. The control unit 140 starts the process shown in Figure 5 upon receiving a command transmitted from the vehicle M's control device, for example, to switch from automatic driving to manual driving. The following process is repeated at the sampling period of the first acquisition unit 111. In actual control, processes are performed to determine abnormalities in the ROM, RAM, and electrodes of the first acquisition unit 111. However, these processes are omitted in the following explanation to facilitate understanding of the technology.

[0034] In step S101 of Figure 5, the control unit 140 acquires capacitance using the first acquisition unit 111. More specifically, the control unit 140 acquires capacitance generated between the electrodes of the capacitive touch sensor and the conductor approaching the gripping unit 110 using the capacitive touch sensor.

[0035] In step S102 of Figure 5, the control unit 140 determines the amount of change in capacitance during the sampling period based on the acquired capacitance. More specifically, the control unit 140 determines the amount of change in capacitance based on the difference between the previously acquired capacitance and the currently acquired capacitance. That is, the sampling period means the period including the start and end of one period. Note that in the first step S102, for example, the control unit 140 may set the previously acquired capacitance to 0 pF.

[0036] The following describes the determination control performed by the control unit 140.

[0037] In step S103 of Figure 5, the control unit 140 determines whether the change in capacitance exceeds a reference change. Specifically, it determines whether the first condition is met. That is, if the change in capacitance is 3pF or more, the control unit 140 proceeds to step S106. If the change in capacitance is less than 3pF, the control unit 140 proceeds to step S104. If the change in capacitance is less than 3pF, the first condition is met.

[0038] In step S104 of Figure 5, the control unit 140 determines the elapsed time. More specifically, the control unit 140 determines the elapsed time by accumulating the time of the sampling period. For example, if the process in step S104 is repeated over three sampling periods, the elapsed time is the total time for those three periods.

[0039] In step S105 of Figure 5, the control unit 140 determines whether the elapsed time is longer than the reference time. More specifically, the control unit 140 determines whether the second condition is met. That is, if the elapsed time is longer than the reference time, the control unit 140 proceeds to step S108. If the elapsed time is longer than the reference time, the second condition is met. If the elapsed time is less than or equal to the reference time, the control unit 140 proceeds to step S107.

[0040] In step S106 of Figure 5, the control unit 140 resets the elapsed time. Therefore, when the control unit 140 performs the next step S105, it accumulates the sampling period time from zero.

[0041] In step S107 of Figure 5, the control unit 140 outputs a hold determination result via the output unit 130. That is, the control unit 140 transmits information to the vehicle M's control device indicating that the gripping unit 110 is being held by the driver DR. For example, the vehicle M's control device switches from automatic driving to manual driving based on the hold determination.

[0042] In step S108 of Figure 5, the control unit 140 processes the data assuming that the non-holding condition, including the first and second conditions, is met. That is, the control unit 140 outputs a non-holding determination as the determination result via the output unit 130. In other words, the control unit 140 transmits information to the vehicle M's control device indicating that the gripping unit 110 is not being held by the driver DR. As a result, the vehicle M's control device notifies the driver DR, for example, via a display mounted on the vehicle M, prompting them to hold the gripping unit 110. The vehicle M's control device may also make this notification via a speaker or lamp mounted on the vehicle M.

[0043] Steps S101 to S108 are repeatedly performed by the control unit 140 until, for example, a command to stop control is received from the control device of the vehicle M.

[0044] Based on the above, in this embodiment, the non-holding condition is met when the amount of change in capacitance is smaller than the reference amount of change over a reference time. When the driver DR is holding the gripping part 110, the capacitance acquired by the first acquisition unit 111 is likely to fluctuate due to the driver's movement. However, when a conductor other than a person is touching the gripping part 110, the capacitance is unlikely to fluctuate as it is when the driver DR is holding the gripping part 110. Therefore, when the amount of change in capacitance is smaller than the reference amount of change, and when that amount of change in capacitance continues over a reference time, it is highly likely that the capacitance is being generated by a conductor other than a person. In other words, when the non-holding condition, including the first and second conditions, is met, it is unlikely that the driver DR is holding the gripping part 110. Thus, the steering device 100 of this embodiment can determine whether or not the driver DR is holding the gripping part 110. When the driver DR is holding the gripping part 110, it is highly likely that the driver DR is focused on driving. Therefore, the steering device 100 of this embodiment can accurately determine whether the driver DR is paying sufficient attention to driving by determining whether or not the driver DR is holding the grip portion 110.

[0045] B. Second Embodiment: Figure 6 is a flowchart showing the control of the second embodiment. The control unit 140 may further determine the determination result to be a non-holding determination, regardless of the first and second conditions, depending on the magnitude of the capacitance acquired by the first acquisition unit 111, before executing the determination control during the sampling period. The configuration of the steering device 100 in the second embodiment is the same as the configuration of the steering device 100 in the first embodiment.

[0046] The process in step S201 in Figure 6 is the same as the process in step S101 in Figure 5.

[0047] In step S202 of Figure 6, the control unit 140 determines whether the acquired capacitance is greater than the reference capacitance. The reference capacitance is set based on the capacitance when the gripping unit 110 is being gripped by the driver DR. For example, the reference capacitance is the minimum capacitance obtained from multiple manual operations by different drivers DRs. That is, if the acquired capacitance is greater than the reference capacitance, there is a high probability that the gripping unit 110 is being gripped by the driver DR. If the acquired capacitance is less than or equal to the reference capacitance, there is a low probability that the gripping unit 110 is being gripped by the driver DR. If the acquired capacitance is greater than the reference capacitance, the control unit 140 proceeds to step S203 to execute the determination control. If the acquired capacitance is less than or equal to the reference capacitance, the control unit 140 proceeds to step S209 to output a non-holding determination. That is, the control unit 140 determines the determination result to be a non-holding determination, regardless of the first and second conditions.

[0048] The processes in steps S204 to S209 in Figure 6 are the same as the processes in steps S103 to S108 in Figure 5.

[0049] In this embodiment, a non-holding determination is output based on the magnitude of the capacitance acquired by the first acquisition unit 111. The capacitance acquired by the first acquisition unit 111 is generated when a conductor approaches. Therefore, if the gripping unit 110 is not being held by the driver DR, there is a high probability that the capacitance acquired by the first acquisition unit 111 will be smaller than the reference capacitance. Accordingly, the steering device 100 of this embodiment determines the determination result to be a non-holding determination when the capacitance is smaller than the reference capacitance. As a result, the steering device 100 of this embodiment can suppress the possibility of erroneous determination occurring in the determination control when there is a possibility that the gripping unit 110 is not being held. Specifically, an erroneous determination is when a holding determination is output because a conductor other than a hand is touching the gripping unit 110.

[0050] C. Third Embodiment: Figure 7 is an explanatory diagram showing the gripping part 110 and the rotating part 120 of the third embodiment. The steering device 100 may use vehicle operation information to determine whether the driver DR has sufficient attention to driving. In the third embodiment, the steering device 100 includes a second acquisition unit 112. The second acquisition unit 112 acquires vehicle operation information representing the operation of the vehicle 10 by the driver DR. More specifically, the second acquisition unit 112 acquires vehicle operation information generated by operation by the driver DR's hand holding the gripping part 110. For example, the second acquisition unit 112 is a steering switch arranged as shown in Figure 7. The second acquisition unit 112 may also be a combination switch. That is, vehicle steering information is acquired when the driver DR presses a steering switch. The other configurations of the steering device 100 of the third embodiment are the same as those of the steering device 100 of the first embodiment.

[0051] Figure 8 is a flowchart showing the control of the third embodiment. In the third embodiment, the control unit 140 further determines the determination result to a hold determination if the third condition is met before executing the determination control during the sampling period, regardless of the first and second conditions. The third condition is that vehicle operation information has been acquired by the second acquisition unit 112. In the above embodiment, a hold determination is made when the non-hold condition is not met. Therefore, in the third embodiment, a hold determination is made when the non-hold condition is not met or when the third condition is not met. The control method of the third embodiment will be described below.

[0052] The processes in steps S301 and S302 in Figure 8 are the same as the processes in steps S201 and S202 in Figure 6.

[0053] In step S303 of Figure 8, the control unit 140 acquires vehicle operation information using the second acquisition unit 112. For example, if the second acquisition unit 112 is a steering switch, the control unit 140 acquires vehicle operation information when the steering switch is pressed.

[0054] In step S304 of Figure 8, the control unit 140 determines whether or not vehicle operation information has been acquired. More specifically, the control unit 140 determines whether or not the third condition is met. If vehicle operation information has been acquired, the control unit 140 proceeds to step S310. If vehicle operation information has been acquired, the third condition is met. If vehicle operation information has not been acquired, the control unit 140 proceeds to step S305.

[0055] The processes in steps S305 to S311 in Figure 8 are the same as the processes in steps S203 to S209 in Figure 6.

[0056] In this embodiment, when vehicle operation information is acquired, there is a high probability that the driver DR is consciously operating the vehicle 10. Therefore, the steering device 100 of this embodiment can more accurately determine whether the driver DR is paying sufficient attention to driving by performing judgment control based on the vehicle operation information.

[0057] Furthermore, in this embodiment, the second acquisition unit 112 acquires vehicle operation information generated by the driver's (DR) hand, which is holding the grip unit 110. Therefore, when vehicle operation information is acquired, the driver (DR) is holding the grip unit 110. For example, the second acquisition unit 112 is a steering switch or a combination switch. Thus, the steering device 100 of this embodiment can more accurately determine whether the driver (DR) has sufficient attention to driving than the embodiment where vehicle operation information is acquired by operation other than by hand.

[0058] D. Fourth Embodiment: The second acquisition unit 112 may acquire vehicle operation information generated by operation by the driver's foot. For example, the second acquisition unit 112 is the accelerator pedal. That is, when the driver presses the accelerator pedal, vehicle steering information is acquired. The second acquisition unit 112 may also be the brake pedal. Furthermore, the non-holding condition may include a fourth condition as a load condition, where the third condition is not met before the first condition. The other configurations of the steering device 100 in the fourth embodiment are the same as those of the steering device 100 in the third embodiment.

[0059] Figure 9 is a control flowchart of the fourth embodiment. The processes in steps S401 and S402 in Figure 9 are the same as steps S301 and S302 in Figure 8.

[0060] The processes in steps S403 to S405 in Figure 9 are the same as the processes in steps S305 to S307 in Figure 8. Note that if the process proceeds to step S405, the first and fourth conditions are met.

[0061] Furthermore, the process in step S406 in Figure 9 is the same as the process in step S303 in Figure 8.

[0062] In step S407 of Figure 9, the control unit 140 determines whether vehicle operation information has been acquired, similar to step S304 of Figure 8. More specifically, the control unit 140 determines whether the third condition is met. If vehicle operation information has been acquired, the control unit 140 proceeds to step S410. If vehicle operation information has been acquired, the third condition is met. If vehicle operation information has not been acquired, the control unit 140 proceeds to step S408.

[0063] The process from steps S408 to S411 in Figure 9 is the same as the process from steps S308 to S311 in Figure 8.

[0064] In this configuration, for the non-retention condition to be satisfied, conditions related to two pieces of information—the change in capacitance and the vehicle operation information—must be met. The second acquisition unit 112 is, for example, the accelerator pedal or the brake pedal. Therefore, foot movements during driving are simpler than hand movements during driving. For this reason, it is more difficult to determine whether the driver (DR) is paying sufficient attention to driving based on vehicle operation information acquired by foot movements than by hand movements. However, the steering device 100 of this embodiment can accurately determine whether the driver (DR) is paying sufficient attention to driving by using both pieces of information, even when vehicle operation information is acquired from foot movements.

[0065] E. Other embodiments: (E1) In the above embodiment, the reference time is 10 minutes. However, the reference time may be other than 10 minutes. The reference time may be 9 minutes or 11 minutes. More specifically, the time required for the change in capacitance to reach the reference change may vary depending on the environment in which the vehicle M is used and the sensitivity of the first acquisition unit 111. For this reason, the reference time should be based on the time required for the change in capacitance to reach the reference change.

[0066] (E2) In the above embodiment, the reference change is 3pF. However, the reference change may be other than 3pF. When the reference change is determined based on the evaluation results in Figure 3, as in the above embodiment, the reference change is within the range of 2.7pF to 3.3pF. Also, the change in capacitance may deviate from the evaluation results in Figure 3 depending on the sensitivity of the first acquisition unit 111 and the structure of the gripping unit 110. For this reason, the reference change should be based on the change in capacitance when the gripping unit 110 is held by the driver DR.

[0067] (E3) In the above embodiment, if the change in capacitance is 3 pF or more, the control unit 140 proceeds to step S106. If the change in capacitance is less than 3 pF, the control unit 140 proceeds to step S104. However, if the change in capacitance is greater than 3 pF, the control unit 140 may proceed to step S106. However, in that case, if the change in capacitance is 3 pF or less, the control unit 140 proceeds to step S104.

[0068] (E4) In the above embodiment, if the elapsed time is longer than the reference time, the control unit 140 proceeds to step S108. If the elapsed time is less than or equal to the reference time, the control unit 140 proceeds to step S107. However, if the elapsed time is greater than or equal to the reference time, the control unit 140 may proceed to step S108. In that case, however, if the elapsed time is shorter than the reference time, the control unit 140 proceeds to step S107.

[0069] (E5) In the above embodiment, if the acquired capacitance is greater than the reference capacitance, the control unit 140 proceeds to step S203 to execute a determination control. If the acquired capacitance is less than or equal to the reference capacitance, the control unit 140 proceeds to step S207 to output a non-retention determination. However, the control unit 140 may proceed to step S203 if the acquired capacitance is greater than or equal to the reference capacitance. However, in that case, the control unit 140 proceeds to step S207 if the acquired capacitance is less than the reference capacitance.

[0070] (E6) In the above embodiment, the gripping portion 110 has an annular shape. However, the gripping portion 110 may have a polygonal annular shape or an elliptical annular shape. Furthermore, the gripping portion 110 is not limited to an annular shape, but may consist of multiple non-contiguous gripping portions 110, such as a right gripping portion 110 and a left gripping portion 110.

[0071] This disclosure is not limited to the embodiments described above, and can be implemented in various configurations without departing from its spirit. For example, the technical features of the embodiments corresponding to the technical features in each form described in the Summary of the Disclosure section can be replaced or combined as appropriate to solve some or all of the above problems, or to achieve some or all of the above effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of Symbols]

[0072] 10...Vehicle, 100...Steering device, 110...Grip part, 111...First acquisition part, 112...Second acquisition part, 120...Rotation part, 121...Hub part, 122...Spoke part, 130...Output part, 140...Control unit, AR...Rotation axis, AX...Axis, DR...Driver, M...Vehicle, S...Space

Claims

1. A vehicle steering system, A gripping portion held by the driver of the vehicle, An output unit that outputs information, The steering device comprises a control unit for controlling the steering device, The gripping portion includes a first acquisition unit that acquires capacitance generated when a conductor approaches the gripping portion, The control unit, Based on the amount of change in capacitance during the sampling period obtained from the capacitance acquired by the first acquisition unit at a predetermined sampling period, a determination control is performed to determine the determination result to either a holding determination indicating that the gripping part is being held by the driver, or a non-holding determination indicating that the gripping part is not being held by the driver. The output unit outputs the determination result, The non-retention determination is made when the non-retention condition is met, and the non-retention condition includes a first condition that the amount of change is smaller than a predetermined standard amount of change, and a second condition that is met over a standard time longer than the sampling period.

2. A steering device according to claim 1, The control unit further, Before executing the determination control during the sampling period, if the acquired capacitance is greater than a predetermined reference capacitance, the determination control is executed. A steering device that, before executing the determination control during the sampling period, determines the determination result to the non-hold determination if the acquired capacitance is smaller than the reference capacitance, regardless of the first and second conditions.

3. A steering device according to claim 1, The aforementioned reference time falls within the range of 9 to 11 minutes. The steering device wherein the aforementioned reference change is within the range of 2.7 pF to 3.3 pF.

4. A steering device according to any one of claims 1 to 3, The steering device further includes a second acquisition unit that acquires vehicle operation information representing the operation of the vehicle by the driver, The steering device further includes a control unit which, if a third condition is met—that the vehicle operation information has been acquired by the second acquisition unit before executing the determination control during the sampling period—decides the determination result to the hold determination, regardless of the first and second conditions.

5. A steering device according to claim 4, The second acquisition unit is a steering device that acquires the vehicle operation information generated by the driver's hand, which is holding the gripping unit.

6. A steering device according to claim 4, The second acquisition unit acquires the vehicle operation information generated by the driver's foot operation, A steering device wherein the non-retention condition further includes a fourth condition that the third condition is not met before the first condition.

Images