JP2018052379A - Grip state determination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether or not a driver of a vehicle grips a steering wheel.SOLUTION: In the case that a contact detection sensor for detecting contact to a steering wheel effectively functions, when the contact detection sensor outputs a contact signal (step 515), or when a magnitude of detection steering torque is not smaller than a first grip determination threshold (step 525), a grip state determination device determines that a driver grips the steering wheel (step 520), and when the detection steering torque is smaller than the first grip determination threshold, and a state that the contact detection sensor outputs a non-contact signal is continued for a first threshold time or longer, the grip state determination device determines that the driver does not grip the steering wheel (step 530, step 535). On the other hand, in the case that the contact detection sensor does not effectively functions, when the magnitude of the detection steering torque is not smaller than a second grip determination threshold which is set smaller than the first grip determination threshold (step 545), the grip state determination device determines that the driver grips the steering wheel (step 520).SELECTED DRAWING: Figure 5

Description

  The present invention relates to a gripping state determination device that determines whether or not a driver of a vehicle is gripping a steering wheel.

  Conventionally, an apparatus has been proposed for determining whether or not a driver is holding a steering wheel (steering wheel) using a capacitance detected by a capacitance-type contact detection sensor when driving the vehicle. (For example, refer to Patent Document 1). Further, it is determined whether or not the driver is holding the steering wheel when driving support control (for example, lane keeping control) of the vehicle is being executed, and it is determined that the driver is not holding the steering wheel. A technique for generating an alarm or stopping driving support control in the case of failure is also well known.

JP 2014-190712 A

  However, a contact detection sensor such as a capacitance type contact sensor is used for a long time, for example, when the temperature exceeds the use range or the driver is driving with gloves. When the output signal of the contact detection sensor is always constant, there is a possibility that the gripping state of the steering wheel by the driver is not correctly detected. In such a case (that is, when the contact detection sensor is not functioning effectively), it is determined whether or not the driver is holding the steering handle by the contact detection sensor. There is a risk that the state is erroneously determined.

  By the way, as a gripping state determination device for determining the gripping state of the steering wheel of the driver, a steering torque sensor for detecting steering torque is provided on the steering shaft, and the magnitude of the steering torque generated on the steering shaft exceeds a threshold value An apparatus that determines that the driver is holding the steering wheel is also known. Therefore, using not only the contact detection sensor but also the steering torque sensor for the determination of the grip state of the steering handle leads to an increase in the determination accuracy of the grip state. Hereinafter, the steering torque detected by the torque sensor is also referred to as “detected steering torque”.

  In the gripping state determination device that determines the gripping state using the detected steering torque, it is possible to determine that the gripping state is occurring even when the driver touches the steering handle lightly. Therefore, it is necessary to set the above threshold value to a value close to zero. On the other hand, even when the driver releases his / her hand from the steering wheel (hereinafter also referred to as “hand-off state” or “hand-off operation 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 becomes a certain value. Accordingly, the threshold value must be set to a value that is not too close to zero.

  However, if the threshold is set to a relatively large value, it is unlikely that the magnitude of the detected steering torque will be greater than or equal to the threshold when the driver is lightly grasping the steering wheel. The possibility of making an erroneous determination increases. In addition, if the threshold value is set to a relatively large value, the possibility of erroneous determination due to road surface torque is reduced, but the gripping state determination device is released when the state where the detected steering torque is lower than the threshold value continues for a threshold time or longer. If it is configured to “determine that a state has occurred”, there is also a problem that it takes a long time until it is determined that a hand-off state has occurred when it is in a really hand-off state.

  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 is highly likely to determine a gripping state of a steering wheel of a driver with high accuracy using a contact detection sensor and a steering torque sensor. .

One of the gripping state determination devices of the present invention (hereinafter also referred to as “the present invention device”)
A steering handle (SW) for steering the vehicle;
A steering shaft (SS) coupled to the steering handle;
A contact detector (13, 10) for detecting 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 handle is gripped by a driver;
With
The controller is
It is determined whether the contact detection unit functions 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 greater than or equal to a first grip determination threshold value. When at least one of the first condition and the second condition that contact with the steering handle is detected by the contact detection unit is satisfied, it is determined that the steering handle is held (step A third determination that “Yes” is determined at 515, “Yes” is determined at step 525, step 520), and the magnitude of the detected steering torque is less than the first grip determination threshold value. The steering handle is not gripped when a state where both the condition and the fourth condition that the contact to the steering handle is not detected by the contact detection unit continues for the first threshold time or longer. Determines that (determination of "No" at step 515, determines a "No" at step 525, determines a "Yes" at step 530, step 535),
When it is determined that the contact detection unit is not functioning effectively (determination of “No” in Step 510), the detected steering torque is smaller than the first grip determination threshold. It is determined that the steering handle is being gripped when the fifth condition that the gripping determination threshold is equal to or greater than 2 gripping determination threshold is satisfied (determination of “Yes” in step 545, step 520) and the detection is made When the condition that the sixth condition that the magnitude of the steering torque is less than the second gripping determination threshold is satisfied continues for the first threshold time or longer, it is determined that the steering handle is not gripped (in step 545). Of “No”, “Yes” in Step 550, Step 535),
It is configured as follows.

  According to this, when the contact detection unit is functioning effectively and the contact detection unit detects contact with the driver's steering wheel, it is determined that the driver is holding the steering wheel. Furthermore, when the contact detection unit functions effectively, when the detected steering torque is greater than or equal to the “relatively large first grip determination threshold value”, the driver grips the steering wheel. It is determined that Therefore, when the magnitude of the steering torque detected due to the influence of the road surface torque increases, the driver grips the steering handle based on the detected steering torque when the driver does not actually grip the steering handle. It is not erroneously determined that

  On the other hand, when the contact detection unit is not functioning effectively, it is determined that the steering handle is being gripped when the detected steering torque is greater than or equal to the “relatively small second grip determination threshold”. When the state where the detected magnitude of the steering torque is not equal to or greater than the “relatively small second gripping determination threshold value” continues for the first threshold time or longer, it is determined that the steering handle is not gripped. Since the second gripping determination threshold is smaller than the first gripping determination threshold, the detected steering torque is equal to or greater than the second gripping determination threshold even when the driver is lightly gripping the steering wheel. . Therefore, the device according to the present invention can reduce the possibility that the driver erroneously determines that the hand-off state has occurred even though the driver is holding the steering wheel.

In another one of the devices of the present invention, “a controller that determines whether or not the steering wheel is held by the driver”
It is determined whether the contact detection unit functions 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 greater than or equal to a first grip determination threshold value. When at least one of the first condition and the second condition that contact with the steering handle is detected by the contact detection unit is satisfied, it is determined that the steering handle is held (step A third determination that “Yes” is determined in step 615, “Yes” is determined in step 625, step 620), and the magnitude of the detected steering torque is less than the first grip determination threshold value. The steering handle is not gripped when a state where both the condition and the fourth condition that the contact to the steering handle is not detected by the contact detection unit continues for the first threshold time or longer. 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. (Determination of “Yes” in step 645, step 620), and the steering handle is gripped when the state where the third condition is satisfied continues for a second threshold time shorter than the first threshold time. ("No" determination at step 645, "Yes" determination at step 650, step 635),
It is configured as follows.

  According to this, when the contact detection unit is functioning effectively and the contact detection unit detects contact with the driver's steering wheel, it is determined that the driver is holding the steering wheel. Furthermore, when the contact detection unit functions effectively, when the detected steering torque is greater than or equal to the “relatively large first grip determination threshold value”, the driver grips the steering wheel. It is determined that Therefore, when the magnitude of the steering torque detected due to the influence of the road surface torque increases, the driver grips the steering handle based on the detected steering torque when the driver does not actually grip the steering handle. It is not erroneously determined that

  On the other hand, when the contact detection unit is not functioning effectively, it is determined that the steering handle is being gripped when the magnitude of the detected steering torque is greater than or equal to the first grip determination threshold, and the detected steering is detected. If the state where the magnitude of the torque is not equal to or greater than the first gripping 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.

  When the magnitude of the detected steering torque is less than the first grip determination threshold, it is highly likely that the driver does not actually grip the steering wheel. Furthermore, when the contact detection unit does not function effectively, the second threshold time is set to a time shorter than the first threshold time. Therefore, according to the above configuration, the device according to the present invention has a possibility of detecting early and surely that the hand-off state has occurred when it is determined that the contact detection unit is not functioning effectively. Can be high.

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

FIG. 1 is a schematic configuration diagram of a gripping 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 cut along a plane along line 1-1. 4A and 4B are graphs showing the relationship between the magnitude of the detected steering torque and the gripping probability of the steering wheel. FIG. 5 is a flowchart showing a grip determination routine executed by the CPU of the driving assistance ECU shown in FIG. FIG. 6 is a flowchart showing a grip determination routine executed by the CPU of the driving assistance ECU provided in the grip state determination device (second device) according to the second embodiment of the present invention.

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

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

  In this specification, the ECU is an 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 implements various functions by executing instructions (programs, routines) stored in the ROM. The driving support ECU 10, the steering ECU 30, and the warning ECU 40 are connected to each other so as to be able to transmit and receive information via a CAN (Controller Area Network) (not shown). 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 assistance ECU 10 is connected to sensors, switches, devices, and the like described below and receives signals from these. Note that these sensors, switches, and the like may be connected to an ECU other than the driving support ECU 10. In this case, detection signals from those sensors and switches are transmitted to the driving support ECU 10 via the CAN.

  Radar sensor 11: The radar sensor 11 acquires information about a road ahead of the host 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 an automobile, and a fixed object such as a utility pole, a tree, and a guardrail. Hereinafter, these three-dimensional objects may be referred to as “targets”. The radar sensor 11 includes a “radar transmission / reception unit and signal processing unit” (not shown). The radar transmitter / receiver radiates millimeter wave radio waves (hereinafter referred to as “millimeter waves”) to the surrounding area of the host vehicle including the front area of the host vehicle, and is reflected by a target existing within the radiation range. A millimeter wave (that is, a reflected wave) is received. The signal processing unit detects each target detected 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 until the reflected wave is received. Relative relationships such as the inter-vehicle distance (vertical distance), relative speed, lateral distance, and relative lateral speed are acquired for each elapse of a predetermined time.

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

  The driving support ECU 10 synthesizes the relative relationship between the host vehicle and the target obtained by the radar sensor 11 and the relative relationship between the host vehicle and the target obtained by the camera device 12. The relative relationship (target information) between the vehicle and the target is determined. Further, the driving assistance ECU 10, based on a pair of left and right image data (road image data) taken by the camera device 12, lane markers (hereinafter referred to as the left and right white lines) of the road (the lane in which the host vehicle is traveling). It is simply referred to as “white line”), and the shape of the road (the radius of curvature indicating the degree of the road bending), the positional relationship between the road and the vehicle, and the like are acquired.

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

  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 detects the steering torque Tr applied to the steering shaft SS connected to the steering handle SW and rotating together with the steering handle SW, and outputs a signal representing the steering torque Tr. The steering torque sensor 15 outputs a steering torque generated when the steering wheel SW is rotated counterclockwise as a positive value, and outputs a steering torque generated when the steering wheel SW is rotated clockwise as a negative value. The steering handle SW and the steering shaft SS are part of a well-known steering mechanism, and the driver can change the turning angle of the steering wheel of the vehicle by rotating (manipulating) the steering handle 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 travel 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 corresponding to the operation state. The driver can select whether or not to execute the lane keeping control (LKA: lane keeping assist control) by operating the operation switch 17.
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 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 the electric power supplied from the motor driver 31, and can apply the steering assist torque to the steering shaft SS and the steering handle or steer the steering wheel by this torque. . When the steering ECU 30 receives an instruction for executing 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 a buzzer 41 and a display 42. The alarm ECU 40 alerts the driver by sounding the buzzer 41 in response to an instruction from the driving support ECU 10 as a “hand-off warning”. Furthermore, the alarm ECU 40 turns on a warning mark (for example, a warning lamp) on the display 42, displays a warning message, or displays the operation status of the driving support control in response to an instruction from the driving support ECU 10. Or display.

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

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

  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 cross-sectional view, and are opposed to each other with a core portion 23 having a circular cross section and an outer shape that is an annular shape along the shape of the steering wheel SW. The upper electrode 21 and the lower electrode 22 are accommodated in the cover portion 25. The cover portion 25 is filled with a dielectric (insulator) 24. In other words, the steering handle SW has a structure in which the core part 23 / dielectric 24 / upper electrode 21 or lower electrode 22 / dielectric 24 / cover part 25 are arranged from the center toward the outside in a cross-sectional view.

  The measurement circuit 13b has a stray capacitance between each of the pair of the 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 the ground, and a capacitance that the measurement circuit 13b itself has. The total capacitance is detected, and the detected capacitance is transmitted to the driving assistance ECU 10. This capacitance changes according to the contact area when the driver's human body (hand) contacts the steering wheel SW. For example, a circuit described in Japanese Patent Application Laid-Open No. 2014-190856 can be adopted as the measurement circuit 13b.

  The contact detection sensor 13 further transmits a different signal to the driving assistance ECU 10 depending on whether or not the value representing the capacitance detected by the measurement circuit 13b exceeds a predetermined threshold value. That is, the contact detection sensor 13 is a signal indicating that the driver's body is in contact with the steering wheel SW when the value representing the capacitance detected by the measurement circuit 13b does not exceed a predetermined threshold value (hereinafter referred to as the driver's body). , Also referred to as “contact signal”) is output to the driving assistance ECU 10. On the other hand, the contact detection sensor 13 is a signal indicating that the driver's body is not in contact with the steering wheel SW when the value indicating the capacitance detected by the measurement circuit 13b exceeds a predetermined threshold (hereinafter referred to as “the body of the driver”). , Also referred to as “non-contact signal”) is output to the driving assistance ECU 10.

<Overview of operation>
Next, an outline of the operation of the first device will be described with reference to FIG. Note that the gripping 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 in order to help understanding. The first device determines whether or not the driver is holding the steering wheel SW, and outputs the determination result. During execution of the lane keeping control, the first device indicates to the driver during the first predetermined period when the determination result indicates “a state in which the driver does not hold the steering wheel SW (in other words, a hand-off driving state)”. A warning (hand-off warning) is generated. Further, if the let-off driving state continues for the second predetermined period despite the warning, the execution of the lane keeping control is stopped.

  The first device uses not only the contact detection sensor 13 but also the steering torque sensor 15 to determine whether or not the steering handle SW is gripped. This is to cope 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 where the output of the contact detection sensor 13 does not correctly represent the gripping state of the steering handle SW is that the steering handle temperature Tsw detected by the steering handle temperature sensor 14 is when the contact detection sensor 13 is temporarily receiving noise. This occurs when the temperature is very high outside the range of the threshold temperature, or when the driver is driving with gloves.

<< 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 grasps the steering handle SW when at least one of the following conditions is satisfied. Determine that a condition 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 value 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 that both of the following conditions are satisfied: When continuing for one threshold time t1th or more, it is determined that a hand-off state in which the steering wheel SW is not gripped has occurred.

(Third condition)
The magnitude of the detected steering torque Tr is less than the “first grip determination threshold value Tr1” (| Tr | <Tr1).
(4th condition)
The contact detection sensor 13 outputs a non-contact signal (the contact to 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 it is determined that the contact detection sensor 13 is not functioning effectively, the first device determines that a 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 value Tr2 smaller than the first grip determination threshold value 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 satisfies the following sixth condition in a state where the steering wheel SW is determined to be gripped. Is continued for “first threshold time t1th” or longer, it is determined that a hand-off state in which the steering wheel SW is not gripped has occurred.
(Sixth condition)
The magnitude of the detected steering torque Tr is less than the second grip determination threshold value Tr2 (| Tr | <Tr2 <Tr1).

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

  As indicated by the gripping probability curve C1 in FIGS. 4A and 4B, the probability Xh that the driver is gripping the steering wheel SW increases as the detected steering torque Tr increases. On the other hand, as shown by the road surface torque distribution curve C2 in FIGS. 4A and 4B, the distribution probability of the road surface torque TrR resulting from the input from the road surface is large in the detected steering torque Tr. It gets smaller.

  When it is determined that the contact detection sensor 13 is functioning effectively, the determination of whether or not the steering handle SW is in the gripping state (hereinafter also simply referred to as “grip determination”) is basically a contact. It should be possible to carry out with high accuracy 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 that the possibility that the determination that the steering handle SW is in the grip state due to the road surface torque is erroneously made is low. Therefore, when it is determined that the contact detection sensor 13 is functioning effectively, the grip determination threshold value to be compared with the magnitude (| Tr |) of the detected steering torque Tr is determined by the driver gripping the steering wheel SW. Is set to the magnitude Tr1 (first torque) of the steering torque when the probability Xh is “relatively high first probability Xh1” (see FIG. 4A).

  On the other hand, when 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, if the grip determination threshold value that is compared with the magnitude (| Tr |) of the detected steering torque Tr to perform grip determination is set to the first torque Tr1, the driver touches the steering wheel SW lightly. In some cases, 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 “hands off warning” is generated or the lane keeping control is stopped unnecessarily. .

  Therefore, when it is determined that the contact detection sensor 13 is not functioning effectively, the first device sets the grip determination threshold value “the probability Xh that the driver is gripping the steering wheel SW is higher than the first probability Xh1. The steering torque magnitude Tr2 (second torque) when the second probability Xh2 is slightly lower is set. As a result, it is possible to avoid generation of useless hand-off warning and 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 assistance ECU 10 (may be simply referred to as “CPU”) is 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 supposed to run.

  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 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 assistance ECU 10 executes lane keeping control.

  Although the lane keeping control is well known, the steering torque is adjusted so that the position of the vehicle is maintained near the target travel line in the “lane (traveling lane) in which the vehicle is traveling”. 32 to control the steering mechanism to assist the driver's steering operation (for example, Japanese Patent Application Laid-Open Nos. 2008-195402, 2009-190464, 2010-6279, and Patent No. No. 4349210, etc.).

  Assume that the current time is immediately after the ignition key switch is 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 to end the present routine tentatively.

  On the other hand, when the value of the driving support flag Xs is set to “1”, the CPU makes a “Yes” determination at step 505 to proceed to step 510 to determine whether or not the contact detection sensor 13 is valid. Determine whether. More specifically, the CPU has a capacitance (detected capacitance) detected by the contact detection sensor 13 within a normal range, and the detected capacitance does not change at all for a relatively long time. If the steering wheel temperature Tsw detected by the steering wheel temperature sensor 14 is not within the situation and 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 functions effectively. In this case, the CPU makes a “Yes” determination at step 510 to proceed to step 515 to determine whether or not the contact detection sensor 13 has detected that “the steering wheel SW is being held by the driver”. . That is, the CPU determines whether or not the contact detection sensor 13 is outputting a contact detection signal.

  It is assumed that the driver is holding the steering wheel SW with his bare hands. In this case, since a contact detection signal is output from the contact detection sensor 13, the CPU makes a “Yes” determination at step 515, proceeds directly to step 520, and sets the grip determination flag Xh to “1”. Thereafter, the CPU proceeds to step 595 to end the present routine tentatively. Note that the value of the grip determination flag Xh is set to “0” in the above-described initial routine. The grip determination flag Xh indicates that the driver is gripping the steering wheel SW when the value is “1”, and the driver is gripping the steering wheel SW when the value is “0”. Indicates that there is no (hand-on operation).

  On the other hand, for example, when the driver holds the steering wheel SW while wearing gloves, a non-contact detection signal may be output from the contact detection sensor 13. In this case, the CPU makes a “No” determination at step 515 to proceed to step 525 to determine whether or not the magnitude | Tr | of the detected steering torque Tr is equal to or greater than the first grip determination threshold (first torque) Tr1. judge.

  When the magnitude | Tr | of the detected steering torque Tr is equal to or greater than the first grip determination threshold value Tr1, the CPU makes a “Yes” determination at step 525 to proceed 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, when the magnitude | Tr | of the detected steering torque Tr is less than the first grip determination threshold value Tr1, the CPU makes a “No” determination at step 525 to proceed to step 530, where this state (ie, the contact detection sensor 13 outputs a non-contact detection signal, and determines whether or not the first state in which the magnitude | Tr | of the detected steering torque Tr is less than the first gripping determination threshold value Tr1 continues for the first threshold time t1th or more. .

  If the first state does not continue for the first threshold time t1th or longer, the CPU makes a “No” determination at step 530 to directly proceed to step 595 to end the present routine tentatively.

  On the other hand, when the first state continues for the first threshold time t1th or more, the CPU makes a “Yes” determination at step 530 to proceed 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 alarm ECU 40 so as to give a “hands off warning”. Then, the CPU proceeds to step 595 to end this routine once.

  By the way, when it is determined that the contact detection sensor 13 is not functioning effectively at the time when the CPU executes the process of step 510, the CPU makes a “No” determination at step 510 and proceeds to step 545 to detect. 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 value (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 greater than the second grip determination threshold value Tr2, the CPU makes a “Yes” determination at step 545 to proceed 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, when the magnitude | Tr | of the detected steering torque Tr is less than the second grip determination threshold value Tr2, the CPU makes a “No” determination at step 545 to proceed to step 550, and this state (ie, the detected steering torque) It is determined whether or not the second state in which the magnitude of Tr | Tr | is less than the second gripping determination threshold value Tr2 continues for the first threshold time t1th or more.

  If this second state does not continue for the first threshold time t1th or longer, the CPU makes a “No” determination at step 550 to directly proceed to step 595 to end the present routine tentatively.

  On the other hand, when the second state continues for the first threshold time t1th or more, the CPU makes a “Yes” determination at step 550 to proceed 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 alarm ECU 40 so as to give 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 the contact detection sensor 13 and the steering torque sensor 15 in combination. Further, the first device uses the contact detection sensor 13 to determine the grip determination threshold (a value that is compared with the magnitude of the detected steering torque Tr for grip 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 grip determination threshold value Tr1 when it is determined that the function is effective.

  As a result, in the first device, even when the driver grips the handle SW with a relatively small force when the contact detection sensor 13 is not functioning effectively, the driver grips the handle SW. It is possible to reduce the possibility of erroneous determination if not.

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

<< When it is determined that the contact detection sensor 13 is functioning effectively >>
When 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) described above. When at least one of the above holds, it is determined that a gripping state in which the steering wheel SW is gripped has occurred.

  When the second device determines that the contact detection sensor 13 is functioning effectively, the second device determines that the steering handle SW is being gripped in the third condition (| Tr | <Tr1) described above. ) And the fourth condition (the contact detection sensor 13 outputs a non-contact signal) are determined to have been released in a state where the steering wheel SW is not gripped when the state where the first condition time t1th is continued for the first time or longer. To 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 a gripping 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 value 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 satisfies the following eighth condition in a state where the steering wheel SW is determined to be gripped. Is continued for “second threshold time t2th shorter than first threshold time t1th” or longer, it is determined that a hand-off 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 value Tr1” shown in FIG. 4A (| Tr | < Tr2). The eighth condition is the same condition as the third condition described above.

  As described above, the second device maintains the grip determination threshold value at a constant value (Tr1) regardless of whether or not the contact detection sensor 13 is functioning effectively, and determines that a hand-off state has occurred. 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 the contact detection sensor 13 is determined to function effectively. .

<Specific operation>
Next, a specific operation of the second device will be described. The CPU of the driving assistance ECU 10 of the second device executes the 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 by 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 processes as steps 505 to 540 shown in FIG. Furthermore, step 645 in FIG. 6 is a step that replaces step 545 in FIG. 5, and step 650 in FIG. 6 is a step that replaces step 550 in FIG. 5. Therefore, in the following, the processing in step 645 and step 650 will be mainly described.

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

  When the magnitude | Tr | of the detected steering torque Tr is equal to or greater than the first grip determination threshold value Tr1, the CPU makes a “Yes” determination at step 645 to proceed 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 value Tr1, the CPU makes a “No” determination at step 645 to proceed to step 650, and this state (ie, the detected steering torque) It is determined whether or not the third state in which the magnitude of Tr | Tr | is less than the first gripping determination threshold value Tr1 continues for “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 longer, the CPU makes a “No” determination at step 650 to directly proceed to step 695 to end the present routine tentatively.

  On the other hand, when the third state continues for the second threshold time t2th or more, the CPU makes a “Yes” determination at step 650 to proceed 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 alarm ECU 40 to give a “hands off warning”. Then, the CPU proceeds to step 695 to end this routine once.

  As described above, the second device performs the grip determination using the contact detection sensor 13 and the steering torque sensor 15 in combination. Further, when the second device determines that the contact detection sensor 13 is not functioning effectively, the second device is in the let-off state when the state in which the magnitude of the steering torque Tr is equal to or greater than the first gripping determination threshold value Tr1 continues. The threshold time t2th for determining that the contact 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 value Tr1, it is highly likely that the driver does not actually grip the steering wheel SW (see FIG. 4A), so the second device. When it is determined that the contact detection sensor 13 is not functioning effectively, it is possible to detect early and reliably that the hand-off state has occurred.

  In addition, this invention is not limited to the said embodiment, A various modified example is employable within the scope of the present invention. For example, the contact detection sensor 13 is not limited to a capacitive contact detection sensor, and may be a resistive touch sensor, a membrane switch, or a pressure detection sensor. In addition, in the above embodiment, the grip determination is performed during the driving support control. However, the grip determination may be performed when the driving support control is not performed.

  Furthermore, although the detection circuit 13b of the contact detection sensor 13 is provided independently of the driving assistance ECU, the driving assistance ECU 10 may include the detection circuit 13b. Further, the contact detection sensor 13 transmits the electrostatic capacity to the driving assistance ECU 10, and the driver grips the steering handle SW by the CPU of the driving assistance ECU 10 comparing the electrostatic capacity with the threshold electrostatic capacity. It may be determined whether or not (contact).

  Further, in the first device, the magnitude of the first determination threshold Tr1 may be set to infinity (or a very 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.

DESCRIPTION OF SYMBOLS 2 ... Grasping state determination apparatus, 10 ... Driving assistance ECU, 11 ... Radar sensor, 12 ... Camera apparatus, 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 handle (steering wheel), SS ... steering shaft.

Claims (2)

A steering handle for steering the vehicle;
A steering shaft coupled to the steering handle;
A contact detection unit for detecting contact of the driver of the vehicle with the steering handle;
A steering torque sensor for detecting a steering torque generated in the steering shaft;
A controller for determining whether or not the steering handle is gripped by a driver;
With
The controller is
Determine whether the contact detector is functioning effectively,
When it is determined that the contact detection unit functions effectively, the steering handle is detected 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 vehicle is detected is determined, the steering handle is determined to be gripped, and the magnitude of the detected steering torque is A state in which both the third condition that is less than the first gripping determination threshold value and the fourth condition that the contact detection unit has not detected contact with the steering wheel has continued for the first threshold time or longer. If the steering handle is determined not to be gripped,
A fifth condition that the magnitude of the detected steering torque is equal to or greater than a second gripping determination threshold that is smaller than the first gripping determination threshold when it is determined that the contact detection unit is not functioning effectively. When the condition is satisfied, it is determined that the steering wheel is gripped, and the sixth condition that the magnitude of the detected steering torque is less than the second grip determination threshold is satisfied. It is determined that the steering wheel is not gripped when it continues for one threshold time or more;
A gripping state determination device configured as described above. A steering handle for steering the vehicle;
A steering shaft coupled to the steering handle;
A contact detection unit for detecting contact of the driver of the vehicle with the steering handle;
A steering torque sensor for detecting a steering torque generated in the steering shaft;
A controller for determining whether or not the steering handle is gripped by a driver;
With
The controller is
Determine whether the contact detector is functioning effectively,
When it is determined that the contact detection unit functions effectively, the steering handle is detected 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 vehicle is detected is determined, the steering handle is determined to be gripped, and the magnitude of the detected steering torque is A state in which both the third condition that is less than the first gripping determination threshold value and the fourth condition that the contact detection unit has not detected contact with the steering wheel has continued for the first threshold time or longer. If the steering handle is determined not to be gripped,
When it is determined that the contact detection unit is not functioning effectively, it is determined that the steering wheel is gripped when the first condition is satisfied, and the third condition is satisfied Determining that the steering wheel is not gripped when continuing for a second threshold time shorter than the first threshold time;
A gripping state determination device configured as described above.

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