JP6631802B2 - Grasping state judgment device - Google Patents

Description

  The present invention relates to a grip state determination device that determines whether a driver of a vehicle is gripping a steering wheel.

  2. Description of the Related Art Conventionally, an apparatus has been proposed that determines whether a driver is gripping a steering wheel (steering wheel) when driving a vehicle, using capacitance detected by a capacitance-type contact detection sensor. (For example, refer to Patent Document 1). Furthermore, it determines whether or not the driver is holding the steering wheel when performing driving assistance control (for example, lane keeping control) of the vehicle, and determines that the driver is not holding the steering wheel. There is also a well-known technique of generating an alarm or stopping the driving support control in the event of the occurrence.

JP 2014-190712 A

  However, a contact detection sensor such as a capacitance-type contact sensor may be used for a long time when its temperature exceeds the operating range or because the driver is wearing gloves or the like and driving. For example, when the output signal of the contact detection sensor is always constant or the like, there is a possibility that the grip state of the steering wheel by the driver is not correctly detected. In such a case (i.e., when the contact detection sensor is not functioning effectively), determining whether or not the driver is holding the steering wheel by the contact detection sensor is equivalent to holding the steering wheel by the driver. There is a possibility that the state is erroneously determined.

  By the way, a steering torque sensor that detects a steering torque is provided on a steering shaft as a grip state determination device that determines a grip state of a steering wheel of a driver, and when a magnitude of the steering torque generated on the steering shaft is equal to or larger than a threshold value. A device that determines that a driver is holding a steering wheel is also known. Therefore, using not only the contact detection sensor but also the steering torque sensor to determine the grip state of the steering wheel leads to an increase in the determination accuracy of the grip state. Note that the steering torque detected by the torque sensor is hereinafter also referred to as “detected steering torque”.

  In the grip state determination device that determines the grip state using the detected steering torque, in order to be able to determine that the grip state is occurring even when the driver is lightly touching the steering wheel. , It is necessary to set the above-mentioned threshold value to a value close to 0. On the other hand, even when the driver has released his / her hand from the steering wheel (hereinafter, also referred to as "released state" or "released driving state"), the torque transmitted from the road surface (hereinafter referred to as "road surface torque"). In some cases, the magnitude of the detected steering torque takes a certain value. Therefore, the magnitude of the threshold has to be set to a value not too close to zero.

  However, if the threshold value is set to a relatively large value, it is unlikely that the magnitude of the detected steering torque becomes equal to or larger than the threshold value when the driver grips the steering wheel lightly. The possibility of erroneous determination increases. Further, when the threshold value is set to a relatively large value, the possibility of erroneous determination due to road surface torque is reduced, but the grip state determination device `` releases when the state where the detected steering torque is lower than the threshold value continues for a threshold time or more. In the case of performing the "determination that a state has occurred", there is a problem that the time required to determine that the release state has occurred when the release state is really long increases.

  The present invention has been made to address the above-described problems. That is, one of the objects of the present invention is to provide a gripping state determination device that has a high possibility of determining the gripping state of a steering wheel of a driver with higher accuracy using a contact detection sensor and a steering torque sensor. .

One of the grip state determination devices of the present invention (hereinafter, also referred to as “the present device”) is:
A steering wheel (SW) for steering the vehicle;
A steering shaft (SS) connected to the steering wheel;
A contact detector (13, 10) for detecting a contact of the driver of the vehicle with the steering wheel;
A steering torque sensor (15) for detecting a steering torque generated in the steering shaft;
A controller (10) for determining whether or not the steering wheel is gripped by a driver;
With
The controller is
It is determined whether the contact detection unit is functioning effectively (step 510),
When it is determined that the contact detection unit is functioning effectively (determination of “Yes” in step 510), the magnitude of the detected steering torque is equal to or larger than the first grip determination threshold. When at least one of a first condition and a second condition that contact with the steering wheel is detected by the contact detection unit is satisfied, it is determined that the steering wheel is gripped (step The determination of “Yes” in 515, the determination of “Yes” in Step 525, Step 520) and the third determination that the magnitude of the detected steering torque is less than the first grip determination threshold value. The steering wheel is not held when the state in which none of the condition and the fourth condition that the contact with the steering wheel is detected by the contact detection unit is continued for a first threshold time or more. Determines that (determination of "No" at step 515, determines a "No" at step 525, determines a "Yes" at step 530, step 535),
If it is determined that the contact detection unit is not functioning effectively (determination of “No” in step 510), the magnitude of the detected steering torque is smaller than the first grip determination threshold. When the fifth condition that the value is equal to or greater than 2 grip determination threshold is satisfied, it is determined that the steering wheel is gripped (determination of “Yes” in step 545, step 520), and the detection is performed. If the state where the sixth condition that the magnitude of the steering torque is smaller than the second gripping determination threshold is satisfied continues for the first threshold time or more, it is determined that the steering wheel is not gripped (at step 545). Determination of “No”, determination of “Yes” in step 550, step 535),
It is configured as follows.

  According to this, when the contact detection unit detects the driver's contact with the steering wheel while the contact detection unit is functioning effectively, it is determined that the driver is holding the steering wheel. Furthermore, when the contact detection unit is functioning effectively, when the magnitude of the detected steering torque is equal to or greater than the “relatively large first gripping determination threshold”, the driver grips the steering wheel. It is determined that there is. Therefore, when the magnitude of the steering torque detected due to the influence of the road surface torque is increased and the driver does not actually grip the steering wheel, the driver grips the steering wheel based on the detected steering torque. No misjudgment is made.

  On the other hand, if the contact detection unit is not functioning effectively, it is determined that the steering wheel is being gripped if the magnitude of the detected steering torque is equal to or larger than the “relatively small second grip determination threshold”. When the state where the magnitude of the detected steering torque is not equal to or greater than the “relatively small second grip determination threshold” continues for the first threshold time or more, it is determined that the steering wheel is not gripped. Since the second grip determination threshold is smaller than the first grip determination threshold, the magnitude of the detected steering torque is equal to or larger than the second grip determination threshold even when the driver is slightly gripping the steering wheel. . Therefore, the device of the present invention can reduce the possibility that the driver is erroneously determined that the release state occurs even though the driver is holding the steering wheel.

The "controller for determining whether or not the steering wheel is gripped by the driver" in another one of the present invention device,
It is determined whether the contact detection unit is functioning effectively (step 610),
When it is determined that the contact detection unit is functioning effectively (determination of “Yes” in step 610), the magnitude of the detected steering torque is equal to or larger than the first grip determination threshold. When at least one of a first condition and a second condition that contact with the steering wheel is detected by the contact detection unit is satisfied, it is determined that the steering wheel is gripped (step The determination of “Yes” in 615, the determination of “Yes” in Step 625, Step 620) and the third determination that the magnitude of the detected steering torque is less than the first grip determination threshold value. The steering wheel is not held when the state in which none of the condition and the fourth condition that the contact with the steering wheel is detected by the contact detection unit is continued for a first threshold time or more. Determines that (determination of "No" at step 615, determines a "No" at step 625, determines a "Yes" at step 630, step 635),
When it is determined that the contact detection unit is not functioning effectively (determination of “No” in step 610), it is determined that the steering wheel is being gripped when the first condition is satisfied. (The determination of “Yes” in step 645, step 620), and when the state where the third condition is satisfied continues for a second threshold time shorter than the first threshold time, the steering wheel is gripped. (Step 645, "No", Step 650, "Yes", Step 635)
It is configured as follows.

  According to this, when the contact detection unit detects the driver's contact with the steering wheel while the contact detection unit is functioning effectively, it is determined that the driver is holding the steering wheel. Furthermore, when the contact detection unit is functioning effectively, when the magnitude of the detected steering torque is equal to or greater than the “relatively large first gripping determination threshold”, the driver grips the steering wheel. It is determined that there is. Therefore, when the magnitude of the steering torque detected due to the influence of the road surface torque is increased and the driver does not actually grip the steering wheel, the driver grips the steering wheel based on the detected steering torque. No misjudgment is made.

  On the other hand, when the contact detection unit is not functioning effectively, when the magnitude of the detected steering torque is equal to or larger than the first grip determination threshold, it is determined that the steering wheel is gripped, and the detected steering is When the state where the magnitude of the torque is not equal to or larger than the first grip determination threshold continues for "second threshold time shorter than the first threshold time" or longer, it is determined that the steering wheel is not gripped.

  If the magnitude of the detected steering torque is less than the first gripping determination threshold, there is a high possibility that the driver has not actually gripped the steering wheel. Further, when the contact detection unit is not functioning effectively, the second threshold time is set to a time shorter than the first threshold time. Therefore, according to the above configuration, the apparatus of the present invention has a possibility to detect the occurrence of a hand-release state earlier and more reliably when it is determined that the contact detection unit is not functioning effectively. Can be higher.

  In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments are attached in parentheses to the configurations of the invention corresponding to the embodiments described later. However, each component of the present invention is not limited to the embodiment defined by the above reference numerals.

FIG. 1 is a schematic configuration diagram of a grip state determination device (first device) according to the first embodiment of the present invention. FIG. 2 is a front view of the steering handle shown in FIG. FIG. 3 is a cross-sectional view of the steering handle shown in FIG. 2 taken along a plane along line 1-1. FIGS. 4A and 4B are graphs showing the relationship between the magnitude of the detected steering torque and the grip probability of the steering wheel. FIG. 5 is a flowchart showing a grip determination routine executed by the CPU of the driving support ECU shown in FIG. FIG. 6 is a flowchart illustrating a grip determination routine executed by the CPU of the driving support ECU included in the grip state determination device (second device) according to the second embodiment of the present invention.

  Hereinafter, a grip state determination device according to each embodiment of the present invention will be described with reference to the drawings. In all the drawings of the embodiments, the same or corresponding portions are denoted by the same reference numerals.

<First embodiment>
(Constitution)
The grip state determination device 2 according to the first embodiment of the present invention (hereinafter, sometimes referred to as “first device”) is mounted on a vehicle (not shown) (not shown). As shown in FIG. 1, the vehicle includes a driving support ECU 10, a steering ECU 30, and a warning ECU 40.

  In this specification, the ECU is an electric control unit (Electric Control Unit) including a microcomputer as a main part, and is also referred to as a “controller”. The microcomputer includes a CPU, a ROM, a RAM, a nonvolatile memory, an interface I / F, and the like. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. The driving support ECU 10, the steering ECU 30, and the alarm ECU 40 are connected to each other via a CAN (Controller Area Network) (not shown) so that information can be transmitted and received. Some or all of these ECUs may be integrated into one ECU. In the present embodiment, the “controller” refers to the driving support ECU 10 unless otherwise specified.

  As shown in FIG. 1, the driving support ECU 10 is connected to sensors, switches, devices, and the like described below, and receives signals therefrom. Note that these sensors, switches, and the like may be connected to an ECU other than the driving support ECU 10. In this case, the detection signals of these sensors and switches are transmitted to the driving support ECU 10 via the CAN.

  Radar sensor 11: The radar sensor 11 acquires information on a road ahead of the own vehicle and a three-dimensional object existing on the road. The three-dimensional object represents, for example, a moving object such as a pedestrian, a bicycle and a car, and a fixed object such as a telephone pole, a tree, and a guardrail. Hereinafter, these three-dimensional objects may be referred to as “targets”. The radar sensor 11 includes a “radar transmitting / receiving unit and a signal processing unit” (both not shown). The radar transmission / reception unit radiates radio waves in the millimeter wave band (hereinafter, referred to as “millimeter waves”) to the surrounding area of the vehicle including the area in front of the vehicle, and is reflected by a target existing within the radiation range. Received millimeter waves (ie, reflected waves). The signal processing unit detects each target based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from when the millimeter wave is transmitted to when the reflected wave is received. , A relative relationship such as an inter-vehicle distance (longitudinal distance), a relative speed, a lateral distance, and a relative lateral speed is acquired every time a predetermined time elapses.

  Camera device 12: The camera device 12 includes a “stereo camera and an image processing unit” (both not shown). The stereo camera captures a landscape of a left area and a right area in front of the vehicle to acquire a pair of left and right image data. The image processing unit calculates and outputs the presence or absence of the target and the relative relationship between the host vehicle and the target based on a pair of left and right image data captured by the stereo camera.

  Note that the driving support ECU 10 synthesizes the relative relationship between the vehicle and the target obtained by the radar sensor 11 and the relative relationship between the vehicle and the target obtained by the camera device 12, thereby obtaining The relative relationship (target information) between the vehicle and the target is determined. Further, the driving support ECU 10 is based on a pair of left and right image data (road image data) photographed by the camera device 12, and based on lane markers (hereinafter, referred to as left and right white lines on the road (the lane in which the host vehicle is traveling)). Recognize the shape of the road (the radius of curvature indicating the degree of curve of the road), and acquire the positional relationship between the road and the vehicle.

  Contact detection sensor 13: The contact detection sensor 13 detects whether the driver is holding the steering wheel SW (when the driver is touching the steering wheel SW), and when the driver is not touching the steering wheel SW. Output different signals from each other. The contact detection sensor 13 actually includes a “capacitance measurement section 13a and a measurement circuit 13b” which will be described later in detail with reference to FIGS. 2 and 3.

  Steering wheel temperature sensor 14: The steering wheel temperature sensor 14 detects the temperature Tsw of the steering wheel SW and outputs a signal representing the steering wheel temperature Tsw.

  Steering torque sensor 15: The steering torque sensor 15 is connected to the steering wheel SW and detects a steering torque Tr applied to the steering shaft SS that rotates together with the steering wheel SW, and outputs a signal representing the steering torque Tr. The steering torque sensor 15 outputs the steering torque generated when the steering wheel SW is rotated to the left as a positive value, and outputs the steering torque generated when the steering wheel SW is rotated to the right as a negative value. The steering wheel SW and the steering shaft SS are part of a well-known steering mechanism, and the driver can change the steering angle of the steered wheels of the vehicle by rotating (operating) the steering wheel SW.

Steering angle sensor 16: The steering angle sensor 16 detects the steering angle θ of the steering wheel SW and outputs a signal representing the steering angle θ.
Vehicle speed sensor 17: The vehicle speed sensor 17 detects a traveling speed (vehicle speed) SPD of the vehicle and outputs a signal representing the vehicle speed SPD.

Operation switch 17: The operation switch 17 is a switch operated by the driver, and outputs a signal according to the operation state. By operating the operation switch 17, the driver can select whether or not to execute lane keeping control (LKA: lane keeping assist control).
Yaw rate sensor 19: The yaw rate sensor 19 detects the yaw rate YRa of the vehicle and outputs a signal representing the yaw rate YRa.

  The steering ECU 30 is a controller of a well-known electric power steering system, and is connected to a motor driver 31. The motor driver 31 is connected to the steering motor 32. The steering motor 32 is incorporated in the steering mechanism. The steering motor 32 generates torque by electric power supplied from the motor driver 31, and can apply a steering assist torque to the steering shaft SS and the steering wheel or steer a steered wheel by using the torque. . When the steering ECU 30 receives an instruction to execute the lane keeping control from the driving support ECU 10, the steering ECU 30 can use the motor driver 31 to steer the steered wheels necessary to maintain the lane in which the vehicle is traveling. .

  The alarm ECU 40 is connected to the buzzer 41 and the display 42. The warning ECU 40 sounds the buzzer 41 in response to an instruction from the driving support ECU 10 as a “hand-off warning” to alert the driver. Further, in response to an instruction from the driving support ECU 10, the warning ECU 40 turns on a warning mark (for example, a warning lamp) on the display 42, displays a warning message, and displays the operation status of the driving support control. Display.

  Hereinafter, the capacitance type contact detection sensor 13 will be described. As described above, the contact detection sensor 13 has the capacitance measurement section 13a and the measurement circuit 13b.

  As shown in FIGS. 2 and 3, the capacitance measuring section 13a is disposed on a steering wheel (steering wheel) SW of the vehicle. More specifically, as shown in FIG. 3, the capacitance measurement section 13a includes an upper electrode 21, a lower electrode 22, a core section 23, and a dielectric (insulator) 24.

  The upper electrode 21 and the lower electrode 22 extend over substantially the entire circumference of the steering wheel SW. The upper electrode 21 and the lower electrode 22 have an arc shape in a cross-sectional view, and face each other across a core portion 23 having a circular cross section and an outer shape that is annular along the shape of the steering wheel SW. The upper electrode 21 and the lower electrode 22 are housed in a cover 25. The inside of the cover 25 is filled with a dielectric (insulator) 24. In other words, the steering wheel SW has a structure in which the core portion 23 / the dielectric 24 / the upper electrode 21 or the lower electrode 22 / the dielectric 24 / the cover portion 25 are arranged from the center to the outside in a sectional view.

  The measurement circuit 13b measures the stray capacitance between each of the pair of upper electrode 21 and the lower electrode 22 and an object (that is, a vehicle body or a human body (hand)) that can be regarded as ground, and the capacitance of the measurement circuit 13b itself. The total capacitance is detected, and the detected capacitance is transmitted to the driving support ECU 10. This capacitance changes according to the contact area when the human body (hand) of the driver contacts the steering wheel SW. Note that, for example, a circuit described in JP-A-2014-190856 can be adopted as the measurement circuit 13b.

  The contact detection sensor 13 further transmits a different signal to the driving support ECU 10 depending on whether the value representing the capacitance detected by the measurement circuit 13b has exceeded a predetermined threshold. That is, when the value representing the capacitance detected by the measurement circuit 13b does not exceed the predetermined threshold, the contact detection sensor 13 outputs a signal indicating that the driver's body is in contact with the steering wheel SW (hereinafter, referred to as a signal). , "Contact signal") to the driving support ECU 10. On the other hand, when the value representing the capacitance detected by the measurement circuit 13b exceeds a predetermined threshold, the contact detection sensor 13 outputs a signal indicating that the driver's body is not in contact with the steering wheel SW (hereinafter, referred to as a signal). , "Non-contact signal") to the driving support ECU 10.

<Overview of operation>
Next, an outline of the operation of the first device will be described with reference to FIG. In addition, the grip probability curve C1 and the road surface torque distribution curve C2 shown in FIG. 4 are shown on a scale different from the actual scale to facilitate understanding. The first device determines whether or not the driver is holding the steering wheel SW, and outputs a result of the determination. During execution of the lane keeping control, the first device provides the driver with the first predetermined period when the determination result indicates “the state in which the driver is not gripping the steering wheel SW (in other words, the hand-off driving state)”. A warning (hand-off warning) is generated. Further, if the release-only driving state continues over the second predetermined period despite the warning, the execution of the lane keeping control is stopped.

  The first device determines whether or not the steering wheel SW is gripped by using not only the contact detection sensor 13 but also the steering torque sensor 15. This is to deal with a situation where the output of the contact detection sensor 13 does not correctly represent the gripping state of the steering wheel SW (when the contact detection sensor 13 is not functioning effectively). The situation in which the output of the contact detection sensor 13 does not correctly represent the gripping state of the steering wheel SW is that if the contact detection sensor 13 is temporarily receiving noise, the steering wheel temperature Tsw detected by the steering wheel temperature sensor 14 becomes smaller. This occurs when the temperature is extremely high outside the threshold temperature range, or when the driver is wearing gloves and driving.

<< When it is determined that the contact detection sensor 13 is functioning effectively >>
More specifically, when the first device determines that the contact detection sensor 13 is functioning effectively, the first device grips the steering wheel SW when at least one of the following conditions is satisfied. It is determined that a state has occurred.

(First condition)
The magnitude (| Tr |) of the steering torque (detected steering torque) Tr detected by the steering torque sensor 15 is equal to or greater than the “first grip determination threshold Tr1” shown in FIG. 4A (| Tr | ≧ Tr1).
(Second condition)
The contact detection sensor 13 outputs a contact signal (contact with the steering wheel SW is detected by the contact detection sensor 13).

  When the first device determines that the contact detection sensor 13 is functioning effectively, the first device determines that the steering wheel SW is being gripped, and determines that the state where both of the following conditions are satisfied is satisfied. When it has continued for one threshold time t1th or more, it is determined that a release state in which the steering wheel SW is not gripped has occurred.

(3rd condition)
The magnitude of the detected steering torque Tr is smaller than the “first grip determination threshold Tr1” (| Tr | <Tr1).
(4th condition)
The contact detection sensor 13 outputs a non-contact signal (contact with the steering wheel SW is not detected by the contact detection sensor 13).

<< When it is determined that the contact detection sensor 13 is not functioning effectively >>
On the other hand, when determining that the contact detection sensor 13 is not functioning effectively, the first device determines that the gripping state in which the steering wheel SW is gripped has occurred when the following fifth condition is satisfied. .
(Fifth condition)
The magnitude of the detected steering torque Tr is equal to or greater than the “second grip determination threshold Tr2 smaller than the first grip determination threshold Tr1” illustrated in FIG. 4B (| Tr | ≧ Tr2, Tr2 <Tr1).

When the first device determines that the contact detection sensor 13 is not functioning effectively, the first device determines that the steering wheel SW is being held, and the following sixth condition is satisfied. Is longer than the "first threshold time t1th", it is determined that a release state in which the steering wheel SW is not gripped has occurred.
(Sixth condition)
The magnitude of the detected steering torque Tr is smaller than the second gripping determination threshold Tr2 (| Tr | <Tr2 <Tr1).

  As described above, when it is determined that the contact detection sensor 13 is not functioning effectively, the threshold value that is compared with the magnitude of the detected steering torque Tr to determine whether the steering wheel SW is in the gripping state ( That is, the second grip determination threshold Tr2) is a value of the detected steering torque Tr for determining whether the steering wheel SW is in the grip state when the contact detection sensor 13 is determined to be functioning effectively. It is smaller than the threshold value compared with the size (that is, the first grip determination threshold value Tr1). Hereinafter, the reason will be described.

  As shown by the grip probability curves C1 in FIGS. 4A and 4B, the greater the magnitude of the detected steering torque Tr, the higher the probability Xh that the driver grips the steering wheel SW. On the other hand, as shown by the road surface torque distribution curves C2 in FIGS. 4A and 4B, the distribution probability of the road surface torque TrR due to the input from the road surface is large when the detected steering torque Tr is large. It becomes smaller.

  When it is determined that the contact detection sensor 13 is functioning effectively, the determination as to whether the steering wheel SW is in the grip state (hereinafter, simply referred to as “grip determination”) is basically a contact. It should be possible to perform the detection accurately based on the detection result of the detection sensor 13. Therefore, it is desirable that the grip determination based on the detected steering torque Tr is performed so as to reduce the possibility that the determination that the steering wheel SW is in the grip state due to the road torque is erroneously made. Therefore, when it is determined that the contact detection sensor 13 is functioning effectively, the grip determination threshold value that is compared with the magnitude (| Tr |) of the detected steering torque Tr is determined when the driver grips the steering wheel SW. The magnitude Tr1 (first torque) of the steering torque when the presence probability Xh is the "relatively high first probability Xh1" is set (see FIG. 4A).

  On the other hand, if it is determined that the contact detection sensor 13 is not functioning effectively, the grip determination must be performed using only the detected steering torque Tr. In this case, when the grip determination threshold value to be compared with the magnitude (| Tr |) of the detected steering torque Tr for performing the grip determination is set to the first torque Tr1, the driver touches the steering wheel SW lightly. In such a case, the magnitude of the detected steering torque Tr does not exceed the grip determination threshold value. As a result, since it is determined that the driver does not hold the steering wheel SW, there is a high possibility that an unnecessary “hand-off warning” is generated or the lane keeping control is unnecessarily stopped. .

  Therefore, when it is determined that the contact detection sensor 13 is not functioning effectively, the first device sets the grip determination threshold to “the probability Xh that the driver is gripping the steering wheel SW is greater than the first probability Xh1. It is set to the magnitude Tr2 (second torque) of the steering torque when the second probability Xh2 is slightly lower. As a result, it is possible to avoid generation of a useless warning and an unnecessary stop of the lane keeping control.

<Specific operation>
Next, a specific operation of the first device will be described. The CPU of the driving support ECU 10 (may be simply referred to as “CPU”) executes a routine shown in the flowchart of FIG. 5 every time a predetermined time elapses while the ignition key switch is set to the ON position. Is to be executed.

  Therefore, when the ignition key switch is in the ON position, the CPU proceeds from step 500 to step 505 at a predetermined timing, and determines whether or not the value of the driving support flag Xs is “1”. The value of the driving support flag Xs is set to “0” in an initial routine (not shown) executed by the CPU immediately after the ignition key switch changes from the off position to the on position. Further, the value of the driving support flag Xs is set to “1” when the execution of the lane keeping control is selected by the operation switch 17 and the vehicle speed SPD is equal to or higher than the threshold vehicle speed SPDth. At this time, the driving support ECU 10 executes the lane keeping control.

  Although the lane keeping control is well known, the steering torque is controlled so that the position of the vehicle is maintained near a target traveling line in a “lane (traveling lane) in which the vehicle is traveling”. The control is applied to the steering mechanism by the H.32 to assist the driver's steering operation (for example, Japanese Patent Application Laid-Open Nos. 2008-195402, 2009-90464, 2010-6279, and 4349210, etc.).

  Assume that the current time is immediately after the ignition key switch has been changed to the on position. In this case, the value of the driving support flag Xs is “0”. Therefore, the CPU makes a “No” determination at step 505 to directly proceed to step 595, and once ends this routine.

  On the other hand, when the value of the driving support flag Xs is set to “1”, the CPU determines “Yes” in step 505 and proceeds to step 510 to determine whether the contact detection sensor 13 is valid. Is determined. More specifically, the CPU determines that the capacitance (detected capacitance) detected by the contact detection sensor 13 is within the normal range, and that the detected capacitance does not change at all for a relatively long time. If not, and the steering wheel temperature Tsw detected by the steering wheel temperature sensor 14 is within the threshold temperature range, it is determined that the contact detection sensor 13 is valid.

  Here, it is assumed that the contact detection sensor 13 is functioning effectively. In this case, the CPU determines “Yes” in step 510 and proceeds to step 515, and determines whether the contact detection sensor 13 detects “the steering wheel SW is being held by the driver”. . That is, the CPU determines whether or not the contact detection sensor 13 outputs a contact detection signal.

  It is assumed that the driver is holding the steering wheel SW with his bare hands. In this case, since the contact detection signal has been output from the contact detection sensor 13, the CPU determines “Yes” in step 515, proceeds directly to step 520, and sets the grip determination flag Xh to “1”. Thereafter, the CPU proceeds to step 595, and once ends this routine. The value of the grip determination flag Xh is set to “0” in the above-described initial routine. When the value of the grip determination flag Xh is “1”, it indicates that the driver is gripping the steering wheel SW, and when the value is “0”, the driver is gripping the steering wheel SW. Indicates that there is no driving (hands-free driving).

  On the other hand, for example, when the driver is gripping the steering wheel SW while wearing gloves, the contact detection sensor 13 may output a non-contact detection signal. In this case, the CPU makes a “No” determination at step 515 and proceeds to step 525 to determine whether the magnitude | Tr | of the detected steering torque Tr is equal to or greater than a first grip determination threshold (first torque) Tr1. judge.

  If the magnitude | Tr | of the detected steering torque Tr is equal to or greater than the first grip determination threshold Tr1, the CPU determines “Yes” in step 525, and proceeds to step 595 via step 520. Therefore, also in this case, the value of the grip determination flag Xh is set to “1”.

  On the other hand, if the magnitude | Tr | of the detected steering torque Tr is less than the first grip determination threshold Tr1, the CPU determines “No” in step 525 and proceeds to step 530, where the CPU proceeds to this state (ie, the contact detection sensor). 13 outputs a non-contact detection signal and determines whether the magnitude | Tr | of the detected steering torque Tr is smaller than the first grip determination threshold Tr1) for a first threshold time t1th or more. .

  If the first state has not continued for the first threshold time t1th or more, the CPU determines “No” in step 530, proceeds directly to step 595, and ends this routine once.

  On the other hand, if the first state has continued for the first threshold time t1th or more, the CPU makes a “Yes” determination in step 530, proceeds to step 535, and sets the value of the grip determination flag Xh to “0”. To "." Thereafter, the CPU proceeds to step 540, and sends an instruction to the warning ECU 40 to issue a "hands-off warning". Then, the CPU proceeds to step 595 to end this routine once.

  By the way, when the CPU determines that the contact detection sensor 13 is not functioning effectively at the time when the CPU executes the process of step 510, the CPU determines “No” in the step 510 and proceeds to step 545 to perform the detection. It is determined whether or not the magnitude | Tr | of the steering torque Tr is equal to or greater than a second grip determination threshold (second torque) Tr2. As described above, the second grip determination threshold (second torque) Tr2 is smaller than the first grip determination threshold (first torque) Tr1.

  When the magnitude | Tr | of the detected steering torque Tr is equal to or larger than the second grip determination threshold Tr2, the CPU determines “Yes” in step 545, and proceeds to step 595 via step 520. Therefore, also in this case, the value of the grip determination flag Xh is set to “1”.

  On the other hand, if the magnitude | Tr | of the detected steering torque Tr is smaller than the second grip determination threshold Tr2, the CPU makes a “No” determination at step 545 and proceeds to step 550, where the CPU proceeds to this state (ie, the detected steering torque). It is determined whether the magnitude | Tr | of the Tr is smaller than the second gripping determination threshold Tr2 (second state) for the first threshold time t1th or more.

  If the second state has not been continued for the first threshold time t1th or more, the CPU determines “No” in step 550, proceeds directly to step 595, and ends this routine once.

  On the other hand, when the second state has continued for the first threshold time t1th or more, the CPU determines “Yes” in step 550, proceeds to step 535, and sets the value of the grip determination flag Xh to “0”. To "." Thereafter, the CPU proceeds to step 540, and sends an instruction to the warning ECU 40 to issue a "hands-off warning". Then, the CPU proceeds to step 595 to end this routine once.

  As described above, the first device performs the grip determination using both the contact detection sensor 13 and the steering torque sensor 15. Further, the first device sets a gripping determination threshold value (a value to be compared with the magnitude of the detected steering torque Tr for gripping determination) Tr2 when it is determined that the contact detection sensor 13 is not functioning effectively. 13 is set to a value smaller than the gripping determination threshold Tr1 when it is determined that the device 13 is functioning effectively.

  As a result, even when the driver is gripping the steering wheel SW with a relatively small force when the contact detection sensor 13 is not functioning effectively, the first device holds the steering wheel SW. It is possible to reduce the possibility of erroneously determining that there is no data.

<Second embodiment>
Next, a grip state determination device 2 (hereinafter, may be referred to as a “second device”) according to a second embodiment of the present invention will be described. The second device is different from the first device only in the conditions for grip determination (particularly, the conditions for determining that the release state has occurred) as described below.

<< When it is determined that the contact detection sensor 13 is functioning effectively >>
If the second device determines that the contact detection sensor 13 is functioning effectively, the first condition (| Tr | ≧ Tr1) and the second condition (the contact detection sensor 13 outputs a contact signal) when the second device determines that the contact detection sensor 13 is functioning effectively. When at least one of the conditions is satisfied, it is determined that the grip state in which the steering wheel SW is gripped has occurred.

  If the second device determines that the contact detection sensor 13 is functioning effectively, it determines that the steering wheel SW is being gripped, and determines that the third condition (| Tr | <Tr1) is satisfied. ) And the fourth condition (the contact detection sensor 13 outputs a non-contact signal) continue for more than the “first threshold time t1th”, it is determined that the release state in which the steering wheel SW is not gripped has occurred. I do. The first threshold time t1th used by the second device may be the same as or different from the first threshold time t1th used by the first device.

<< When it is determined that the contact detection sensor 13 is not functioning effectively >>
On the other hand, when it is determined that the contact detection sensor 13 is not functioning effectively, the second device determines that the grip state in which the steering wheel SW is gripped has occurred when the following seventh condition is satisfied. . The seventh condition is the same as the first condition described above.
(Seventh condition)
The magnitude (| Tr |) of the steering torque (detected steering torque) Tr detected by the steering torque sensor 15 is equal to or greater than the “first grip determination threshold Tr1” shown in FIG. 4A (| Tr | ≧ Tr1).

When the second device determines that the contact detection sensor 13 is not functioning effectively, the second device determines that the steering wheel SW is being held, and the following eighth condition is satisfied. For more than the “second threshold time t2th shorter than the first threshold time t1th”, it is determined that a release state in which the steering wheel SW is not gripped has occurred.
(Eighth condition)
The magnitude (| Tr |) of the steering torque (detected steering torque) Tr detected by the steering torque sensor 15 is less than the "first grip determination threshold Tr1" shown in FIG. 4A (| Tr | < Tr2). The eighth condition is the same as the third condition described above.

  As described above, the second device determines that the release state has occurred while maintaining the grip determination threshold at a constant value (Tr1) regardless of whether the contact detection sensor 13 is functioning effectively. The threshold time is set to a shorter time when it is determined that the contact detection sensor 13 is not functioning effectively than when it is determined that the contact detection sensor 13 is functioning effectively. .

<Specific operation>
Next, a specific operation of the second device will be described. The CPU of the driving support ECU 10 of the second device executes a grip determination routine shown in FIG. 6 instead of the grip determination routine shown in FIG. 5 executed by the CPU of the first device. That is, the CPU of the second device executes the routine shown in the flowchart of FIG. 6 every time a predetermined time elapses while the ignition key switch is set to the ON position.

  Steps 605 to 640 shown in FIG. 6 are steps for performing the same processing as steps 505 to 540 shown in FIG. Further, step 645 in FIG. 6 is a step replacing step 545 in FIG. 5, and step 650 in FIG. 6 is a step replacing step 550 in FIG. Accordingly, hereinafter, the processing of steps 645 and 650 will be mainly described.

  When the CPU determines “No” in step 610 because the contact detection sensor 13 is not functioning effectively, the CPU proceeds to step 645 and determines the magnitude | Tr | of the detected steering torque Tr as the first grip determination. It is determined whether or not it is equal to or more than a threshold value (first torque) Tr1.

  If the magnitude | Tr | of the detected steering torque Tr is equal to or greater than the first grip determination threshold Tr1, the CPU determines “Yes” in step 645, and proceeds to step 695 via step 620. Therefore, in this case, the value of the grip determination flag Xh is set to “1”.

  On the other hand, if the magnitude | Tr | of the detected steering torque Tr is less than the first grip determination threshold Tr1, the CPU determines “No” in step 645 and proceeds to step 650, where the CPU proceeds to this state (ie, the detected steering torque). It is determined whether the size | Tr | of the Tr is less than the first gripping determination threshold Tr1 (the third state) is equal to or longer than the “second threshold time t2th shorter than the first threshold time t1th”.

  If the third state has not continued for the second threshold time t2th or more, the CPU determines “No” in step 650, proceeds directly to step 695, and ends the present routine once.

  On the other hand, if the third state has continued for the second threshold time t2th or more, the CPU determines “Yes” in step 650 and proceeds to step 635, and sets the value of the grip determination flag Xh to “0”. To "." Thereafter, the CPU proceeds to step 640 and sends an instruction to the warning ECU 40 to issue a "hands-off warning". Then, the CPU proceeds to step 695 and ends this routine once.

  As described above, the second device performs the grip determination by using the contact detection sensor 13 and the steering torque sensor 15 together. Further, when the second device determines that the contact detection sensor 13 is not functioning effectively, the release state is determined when the state in which the magnitude of the steering torque Tr is equal to or more than the first grip determination threshold Tr1 continues for a long time. The threshold time t2th for determining that the occurrence has occurred is set to a value shorter than the threshold time t1th when it is determined that the contact detection sensor 13 is functioning effectively.

  When the magnitude of the steering torque Tr is less than the first grip determination threshold Tr1, it is highly likely that the driver has not actually gripped the steering wheel SW (see FIG. 4A), so the second device. In the case where it is determined that the contact detection sensor 13 is not functioning effectively, it is possible to detect the occurrence of the hand-release state earlier and more reliably.

  Note that the present invention is not limited to the above embodiment, and various modifications can be adopted within the scope of the present invention. For example, the contact detection sensor 13 is not limited to a capacitance type contact detection sensor, and may be a resistive film type touch sensor, a membrane switch, a pressure detection sensor, or the like. In addition, in the above embodiment, the grip determination is performed during the driving support control, but the grip determination may be performed when the driving support control is not performed.

  Further, although the detection circuit 13b of the contact detection sensor 13 is provided independently of the driving support ECU, the detection circuit 13b may be built in the driving support ECU 10. Further, the contact detection sensor 13 transmits the capacitance to the driving support ECU 10, and the CPU of the driving support ECU 10 compares the capacitance with the threshold capacitance, whereby the driver grips the steering wheel SW. (Contact) may be determined.

  Furthermore, in the first device, the magnitude of the first determination threshold Tr1 may be set to infinity (or an extremely large value). According to this, when it is determined that the contact detection sensor 13 is functioning effectively, the grip determination based on the magnitude of the steering torque Tr detected by the torque sensor 15 is substantially invalidated.

2 ... Grip state determination device, 10 ... Drive support ECU, 11 ... Radar sensor, 12 ... Camera device, 13 ... Contact detection sensor, 14 ... Steering wheel temperature sensor, 15 ... Steering torque sensor, 16 ... Steering angle sensor, 17 ... Vehicle speed sensor, 18: operation switch, 19: yaw rate sensor, 30: steering ECU, 40: alarm ECU, SW: steering wheel (steering wheel), SS: steering shaft.

Claims (2)

A steering wheel for steering the vehicle;
A steering shaft connected to the steering wheel;
A contact detection unit that detects contact of the driver of the vehicle with the steering wheel;
A steering torque sensor that detects a steering torque generated in the steering shaft;
A controller for determining whether or not the steering wheel is gripped by a driver;
With
The controller is
Determine whether the contact detection unit is functioning effectively,
When it is determined that the contact detection unit is functioning effectively, the steering wheel is determined by the first condition that the magnitude of the detected steering torque is equal to or greater than a first grip determination threshold value and the contact detection unit. When at least one of the second conditions that contact with the steering wheel is detected is satisfied, it is determined that the steering wheel is being gripped, and the magnitude of the detected steering torque is the The state where both the third condition that the value is less than the first grip determination threshold and the fourth condition that the contact with the steering wheel is not detected by the contact detection unit has been satisfied has continued for the first threshold time or more. In this case, it is determined that the steering wheel is not gripped,
When it is determined that the contact detection unit is not functioning effectively, a fifth condition that the magnitude of the detected steering torque is equal to or greater than a second grip determination threshold smaller than the first grip determination threshold Is satisfied, it is determined that the steering wheel is being gripped, and the state in which the sixth condition that the magnitude of the detected steering torque is smaller than the second grip determination threshold is satisfied is the second state. It is determined that the steering wheel has not been gripped if it has continued for one threshold time or more,
Holding state determination device configured as described above. A steering wheel for steering the vehicle;
A steering shaft connected to the steering wheel;
A contact detection unit that detects contact of the driver of the vehicle with the steering wheel;
A steering torque sensor that detects a steering torque generated in the steering shaft;
A controller for determining whether or not the steering wheel is being gripped by a driver;
With
The controller is
Determine whether the contact detection unit is functioning effectively,
When it is determined that the contact detection unit is functioning effectively, the steering wheel is determined by the first condition that the magnitude of the detected steering torque is equal to or greater than a first grip determination threshold value and the contact detection unit. When at least one of the second conditions that contact with the steering wheel is detected is satisfied, it is determined that the steering wheel is being gripped, and the magnitude of the detected steering torque is The state where both the third condition that the value is less than the first grip determination threshold and the fourth condition that the contact with the steering wheel is not detected by the contact detection unit has been satisfied has continued for the first threshold time or more. In this case, it is determined that the steering wheel is not gripped,
When it is determined that the contact detection unit is not functioning effectively, it is determined that the steering wheel is being gripped when the first condition is satisfied, and when the third condition is satisfied. It is determined that the steering wheel has not been gripped when the steering wheel has not been gripped when it has continued for a second threshold time shorter than the first threshold time.
Holding state determination device configured as described above.

Images