JP2017124771A - Driving support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving support device that is prevented or suppressed from making a driver feel danger when the driver performs operation for turning a handle in order to avoid a front obstacle by automatic steering.SOLUTION: A driver in its own vehicle V straight travelling by automatic steering control by a controller U, performs operation for turning a handle to the right in which a lateral pylon 22 (a lateral obstacle) exists in order to avoid a front pylon 21 (a front obstacle). When the driver performs the operation for turning the handle, the vehicle is automatically steered so that a situation (degrees of change) where scenery through a front window glass 31 changes is kept constant, which can prevent or suppress sight lines of the driver from unnecessarily moving (prevent or suppress a danger feeling). The degrees of change of the scenery can be determined based on an angle change rate of an optical flow (shown by arrows in figures 2-5) as a benchmark.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a driving support apparatus that performs automatic steering.

  For driving assistance, for example, in lane keeping control, automatic steering is performed so that the vehicle travels in the current traveling lane, and in automatic driving, automatic steering is performed including lane change and avoiding obstacles ahead. Is called. In Patent Document 1, as automatic steering when a front obstacle is present, a side of the front obstacle is allowed to pass while avoiding the front obstacle so that the traveling locus of the host vehicle is a sigmoid curve. Are disclosed. That is, as the steering wheel operation for avoiding the front obstacle, the steering operation for avoiding the front obstacle from the straight traveling state, and then returning to the straight traveling again so as to pass the side of the front obstacle. And a handle for turning back the handle.

JP 2014-218192 A

  It has been found that when steering control is performed to avoid a front obstacle by automatic steering, some drivers may feel danger (tension). After pursuing such a cause, it has been found that it may be caused by the movement of the driver's line of sight. In other words, the driver looks at the scenery (scenery) ahead (including diagonally forward) through the windshield, but the scenery flows laterally as the steering wheel is turned, and the scenery flows to the driver. It has been found that the line of sight of the camera is considerably deviated from the front obstacle and the vicinity thereof, and the danger is caused by such movement of the line of sight. In particular, even when the steering wheel is turned in the same way, the flow of scenery when avoiding obstacles differs due to the difference in the travel trajectory for avoiding obstacles and the difference in vehicle speed. As a result, it has been found that the above-described line-of-sight movement is likely to occur.

  The present invention has been made in view of the above circumstances, and the purpose of the present invention is to feel unnecessary danger to the driver when the steering wheel is turned in order to avoid a front obstacle by automatic steering. An object of the present invention is to provide a driving support device that can prevent or suppress the situation that the user makes it happen.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
A driving support device for a vehicle that performs automatic steering so as to avoid a front obstacle by a steering control means,
When the steering control means performs a steering operation to avoid the front obstacle, automatic steering control is performed so that the degree of change of the scenery viewed from the driver through the front window glass is constant. Equipped with a steering control device,
It is like that. According to the above solution, the scenery viewed through the front windshield flows laterally by performing the cutting operation of the steering wheel, but the degree of change in the scenery flow is constant, so the driver Can maintain a state in which the line of sight is directed to the front obstacle without being particularly conscious of the flow of the scenery, and can prevent or suppress the situation where the gaze is moved greatly from the front obstacle and the danger is felt .

A preferred mode based on the above solution is as described in claim 2 and the following. That is,
Optical flow detection means for detecting an optical flow indicating the flow of the landscape,
The steering control means controls automatic steering so that the angle change rate of the optical flow detected by the optical flow detection means is constant.
(Corresponding to claim 2). In this case, the change degree of the landscape can be controlled to be constant by using a physical index called an optical flow angle change rate.

  The optical flow detection means detects an optical flow limited to a partial area range that is a front area of the driver out of the entire area range of the front window glass (corresponding to claim 3). In this case, the optical flow may be detected with a limited area range that affects the driver, which is preferable in reducing the burden on the control system.

It further comprises vehicle speed detecting means for detecting the vehicle speed,
When the vehicle speed detected by the vehicle speed detection means is low, the steering control means makes the collision margin time for a dangerous object existing in the direction of turning the steering wheel around the host vehicle longer than when the vehicle speed is high. Automatic steering control,
(Corresponding to claim 4). In this case, it is preferable to prevent or suppress a situation in which a side obstacle present in the cutting direction of the handle is felt dangerous.

  ADVANTAGE OF THE INVENTION According to this invention, the situation which makes a driver | operator feel unnecessarily dangerous can be prevented or suppressed when a steering wheel is cut and operated for avoiding a front obstacle by automatic steering.

The figure for demonstrating the motion of the own vehicle at the time of avoiding a front obstacle. The figure which shows the optical flow in the straight-ahead state before performing the cutting operation of a handle | steering-wheel. The figure which shows the optical flow when a handle | steering-wheel is cut and operated. The figure which shows the optical flow when a handle | steering-wheel is returned and operated. The figure which shows the optical flow when a handle | steering-wheel is made into a straight-ahead state again. Data showing the danger of obstacles ahead. Data showing the danger to side obstacles. Data showing the variation in danger. Data showing the effect of the angle change rate and change of the optical flow on the driver's eye movement. Data showing the relationship between the maximum value of the optical flow angle change rate and the presence or absence of eye movement. The figure which shows the condition which set the direction which a test subject looks at in multiple positions, when driving | running | working in the condition like FIG. The figure which shows the example which detects a test subject's danger by the combination of mental sweating and an instantaneous heart rate. The data which shows the correspondence of the test subject's gaze direction shown in FIG. 11, the angle change rate of an optical flow, the reciprocal number of collision allowance time, and danger. The figure which shows the example of a control system of this invention. The flowchart which shows the example of control of this invention.

  First, referring to FIG. 1, an experimental example for verifying a sense of danger felt by the driver when automatic steering is performed to avoid a front obstacle will be described. In the embodiment, automatic driving is performed, and automatic steering is performed as part of this automatic driving.

  First, 11 is a travel path on which the host vehicle V is traveling. The host vehicle V travels from the left side to the right side in the drawing on the left end of the travel path 11. A front pylon 21 serving as a front obstacle is located on the left side of the traveling path 11 in front of the host vehicle V. In addition to the right side of the traveling path 11, a plurality of side pylons 22 are positioned at intervals in the traveling direction on the own vehicle V side with respect to the front pylon 21.

  A traveling locus (traveling route) for the host vehicle V to avoid the front pylon 21 is indicated by K in the figure. The traveling locus K of the host vehicle V is such that a steering wheel cutting operation is performed to the right from the straight traveling, and then a steering wheel switching operation is performed so that the vehicle travels straight on the side (right side) of the front pylon 21. Is set to A section indicated by a circle 1 in the figure is a section from the start of cutting of the handle to the front pylon 21. A section indicated by a circle 2 is a section from the start of turning the handle to the end of turning back the handle (the handle returns to the neutral position), and is a section in which the handle is being operated. Further, a section indicated by a circle 3 indicates an interval between the front pylon 21 and the side pylon 22 positioned on the right side of the front pylon 21 among the plurality of side pylon 22, and the host vehicle V has the two pylon 21. And 22 is passed.

  FIGS. 2 to 5 show changes in the optical flow visually observed by the driver when the host vehicle V is automatically driven along the traveling locus K. FIG. 2 to 5, the front window glass is indicated by reference numeral 31, the instrument panel is indicated by reference numeral 32, the roof panel is indicated by reference numeral 33, and the front pillar is indicated by reference numeral 34. The host vehicle V is a right-hand drive vehicle with a handle (steering handle) 30 positioned on the right side.

  In FIG. 2 to FIG. 5, a region α that is sufficiently smaller than the entire area of the front windshield 31 is set in the region in front of the steering wheel 5 (that is, in front of the driver), and the optical flow in this region α is detected. Is done. The optical flow indicates a state in which a landscape flows when the driver looks forward while traveling and has a direction component and a velocity component. In other words, the optical flow shows the flow of the landscape. In particular, among the optical flows detected in the region α, the flow toward the center of the driver greatly affects the movement of the driver's line of sight. Note that the optical flow (the maximum value and the angle change rate) used in the following description is for an optical flow that occupies a large proportion of the optical flow detected in the region α (the mainstream).

  2 to 5, the direction of the optical flow in the region α is indicated by an arrow. FIG. 2 shows an optical flow corresponding to the point N1 (during straight traveling) in FIG. FIG. 3 shows an optical flow at the point N2 (during cutting of the handle) in FIG. FIG. 4 shows an optical flow at the point N3 (during the steering wheel turning back) in FIG. FIG. 5 shows an optical flow at point N4 (when the handle returns to neutral) in FIG.

  The optical flow at the point N1 is such that it flows backward and considerably downward. The optical flow at the point N2 is a downward flow in the left direction because the host vehicle V is steered in the right direction, but the degree of the downward direction is small. The optical flow at the point N3 is a rightward and downward flow because the steering wheel is being returned, but the degree of the downward flow is smaller than in the case of FIG. Although the optical flow at the point N4 is in a straight traveling state, it is a point in time immediately after the return operation of the steering wheel is completed, and thus the flow is close to that in FIG. 2, but the downward degree is small.

  The angle change rate of the optical flow as shown in FIGS. 2 to 5 is the amount of change per unit time of the angle formed by the arrow indicating the direction of the optical flow (deg / s). The greater the angle change rate of the optical flow, the higher the degree of landscape change. And the driver has a habit of moving the line of sight and the line of sight according to the change of the scenery, and the driver may be concerned about the newly appearing scenery and move the line of sight in that direction. It will be expensive. In particular, when avoiding an obstacle, line-of-sight movement is likely to occur due to a large difference in the degree of change in scenery due to a difference in travel locus and vehicle speed.

  During the turning of the steering wheel, since the host vehicle V is on the side toward the side pylon 22, the optical flow corresponding to the side pylon 22 appears greatly in the region α. That is, the driver has a high possibility of starting the line of sight toward the side pylon 22. While the steering wheel is being cut, the host vehicle V may move toward the side pylon 22, and the driver is likely to feel danger with respect to the side pylon 22.

  Next, the relationship between the collision margin time TTC (Time-To-Collision) and the danger (tension) due to the driver's subjectivity will be described. First, FIG. 6 and FIG. 7 show experimental data when the subject is seated in the driver's seat of the host vehicle V shown in FIG. Is the reciprocal of the collision margin time TTC, and the vertical axis is the sense of danger (subjectivity). Note that the larger the reciprocal of the collision margin time TTC, the shorter the time until the collision.

  FIG. 6 shows a sense of danger for the front pylon 21. The feeling of danger with respect to the front pylon 21 is small in variation among subjects. FIG. 7 shows a sense of danger for the side pylon 22. The feeling of danger with respect to the side pylon 22 varies greatly depending on the driver (subject).

  FIG. 8 shows the result of analyzing the visual behavior of the subject in cases where the sense of danger for the side pylon 22 is greatly deviated from the average characteristic (indicated by γ in the figure) and in cases where it is not (indicated by β in the figure). is there. As a result of this analysis, it has been found that in a case that deviates greatly from the average characteristic, the line of sight tends to be directed to other than the object to be seen (in the embodiment, the front pylon 21 and its vicinity).

  As described above, it has been found that the movement of the line of sight other than the object to be viewed has a great relationship with the degree of change of the landscape, that is, the angle change rate of the optical flow. That is, FIG. 9 shows the difference between the case where there is no line-of-sight movement from the object to be viewed and the case where there is a line-of-sight movement, with the horizontal axis representing the time elapsed and the vertical axis representing the optical flow angle change rate. As is apparent from FIG. 9, if the angle change rate of the optical flow is constant (substantially constant) or the angle change rate of the optical flow is small, the line of sight is not moved. On the other hand, when the angle change rate of the optical flow is large or when the optical flow changes to a large state, it indicates that the line-of-sight movement occurs.

  FIG. 10 shows the relationship between the maximum value of the angle change rate of the optical flow and the frequency (normalization processing) of the presence or absence of eye movement. As is apparent from FIG. 10, it is understood that the greater the maximum value of the optical flow, the higher the frequency of eye movement.

  11 to 13 set the line-of-sight direction that the subject should see in FIG. 11 corresponding to FIG. 1 as follows. First, it is assumed that the front pylon 21 is “1”. When the side pylon 22 located farthest from the host vehicle V among the side pylon 22 is designated as “2”. “3” is defined as the point immediately adjacent to the front pylon 21 and “4” is defined as the far extension position of “3”. Further, among the plurality of side pylon 22, a position on the extension of the host vehicle V in the steering direction of the handle is set to “5”.

  FIG. 12 shows a method for detecting a subject's sense of danger based on the subject's mental sweating and instantaneous heart rate. When you feel caution, mental sweating increases but instantaneous heart rate decreases. On the other hand, when feeling dangerous, both mental sweating and instantaneous heart rate rise. Both the value related to mental sweating and the instantaneous heart rate were detected by a sensor attached to the subject.

  FIG. 13 shows the subject's sense of danger according to the difference in the gaze direction using the above-described mental sweating and instantaneous heart rate. As can be seen from FIG. 13, the side pylon 22 ("5" in FIG. 11) in which the subject's line of sight exists in the direction of cutting the handle at an elapsed time of about 3 seconds when the angle change rate of the optical flow greatly decreased. (See (a) and (b) of FIG. 11), and immediately after that, it is in a tension state showing a sense of danger (see (d) and (e) of FIG. 11). Understood. And as shown in (c) of Drawing 11, the reciprocal number of collision margin time TTC has also raised greatly (increased danger degree). On the other hand, it is understood that there is no danger when the optical flow angle change rate is constant or substantially constant, or when the optical flow angle change rate is small.

  According to the present invention, when the steering wheel is turned, the angle change rate of the optical flow, which is the degree of change of the landscape described above, is constant (including almost constant), thereby giving the driver a sense of danger. It was made not to feel. Hereinafter, control examples according to the present invention will be described.

  First, FIG. 14 shows an example of a control system of the present invention. U is a controller (control unit) configured using a microcomputer. Signals from various sensors or devices S1 to S4 are input to the controller U. That is, S1 is a navigation device, and map information and host vehicle position information are obtained. S2 is a vehicle speed sensor that detects the vehicle speed. S3 is a camera outside the vehicle, which obtains the situation in front of the host vehicle V, and detects an optical flow in the region α as shown in FIGS. S4 is a radar that detects the distance to a front obstacle or the like. An optical flow detection camera may be separately provided (for example, installed on the instrument panel 32 in front of the driver's seat).

  The controller U controls various devices S11 to S13 for automatic operation. In other words, S11 is a throttle actuator for controlling the vehicle speed (acceleration, deceleration, vehicle speed maintenance), S12 is a brake actuator for decelerating or stopping, and S13 is power. A steering device for automatically steering the handle 35.

  FIG. 15 is a flowchart showing a control amount of automatic driving by the controller U, and particularly focuses on control for avoiding a front obstacle (equivalent to the front pylon 21 in FIG. 1). In the following description, Q indicates a step. First, in Q1, signals from various sensors or devices S1 to S4 are input. Thereafter, in Q2, an automatic driving is performed by a known method (execution of automatic driving according to the set contents by setting the vehicle speed and the traveling locus).

  After Q2, an optical flow is detected at Q3. In Q4, it is determined whether or not steering is necessary (for example, determination of necessity of steering for avoiding the front pylon 21 in FIG. 1). If the determination in Q4 is NO, the process returns as it is.

  If the determination in Q4 is YES, the steering timing (timing to start turning the steering wheel) is determined in Q5 so that the detected angle change rate of the optical flow is constant. Thereafter, the steering of the steering wheel is executed at the steering timing determined at Q5 in Q6.

  Q5 and Q6 are automatic steering controls for turning the steering wheel, but what controls the optical flow constant? This is performed for a period from the start of the handle cut to the start of the handle cut back.

  Here, when the vehicle speed is low, as compared with when the vehicle speed is high, the cut amount of the handle required for the lateral movement for avoiding the front obstacle is increased, and the direction of the host vehicle V is the side obstacle (FIG. 1). The degree of facing the side pylon 22) from the front direction increases, and the danger is more easily felt. For this reason, when the vehicle speed is low, it is preferable to increase the collision margin time TTC used when determining the avoidance steering timing (timing for starting the steering operation of the steering wheel) compared to when the vehicle speed is high (the steering wheel time). The start timing of the cutting is set so that the distance from the front obstacle is made larger (section distance indicated by circle 1 in FIG. 1).

  Although the embodiments have been described above, the present invention is not limited to the embodiments, and appropriate modifications can be made within the scope of the claims. The present invention can be applied to any vehicle that performs automatic steering. The setting of the travel locus for avoiding the front obstacle can be made by an appropriate method (appropriate control logic). The degree of change of the scenery viewed by the driver through the front window glass can be acquired from an image captured by the outside camera S3, for example, without using the optical flow. Each step or step group shown in the flowchart indicates the function of the controller U, and the name indicating the function can be attached to the name of the means so as to be grasped as a constituent requirement of the controller U. Of course, the object of the present invention is not limited to what is explicitly stated, but also implicitly includes providing what is substantially preferred or expressed as an advantage.

  The present invention is preferable in performing avoidance control of a front obstacle.

V: Own vehicle K: Traveling track (traveling route)
11: Runway 21: Front pylon (front obstacle)
22: Side pylon (side obstacle)
31: Front window glass 35: Steering handle α: Area (for optical flow detection)

Claims (4)

A driving support device for a vehicle that performs automatic steering so as to avoid a front obstacle by a steering control means,
When the steering control means performs a steering operation to avoid the front obstacle, automatic steering control is performed so that the degree of change of the scenery viewed from the driver through the front window glass is constant. Equipped with a steering control device,
A driving support device characterized by that. In claim 1,
Optical flow detection means for detecting an optical flow indicating the flow of the landscape,
The steering control means controls automatic steering so that the angle change rate of the optical flow detected by the optical flow detection means is constant.
A driving support device characterized by that. In claim 2,
The driving support device according to claim 1, wherein the optical flow detection means detects an optical flow limited to a partial area range that is a front area of the driver in the entire area range of the front window glass. In any one of Claims 1 thru | or 3,
It further comprises vehicle speed detecting means for detecting the vehicle speed,
When the vehicle speed detected by the vehicle speed detection means is low, the steering control means makes the collision margin time for a dangerous object existing in the direction of turning the steering wheel around the host vehicle longer than when the vehicle speed is high. Automatic steering control,
A driving support device characterized by that.

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