JP2017124772A - 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 unnecessarily, when its own vehicle travels on an avoidance route 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 small, which can prevent or suppress the driver from feeling danger. 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.

  The present invention has been made in view of the above circumstances, and its purpose is to unnecessarily cause danger to the driver when traveling on an avoidance route for avoiding a front obstacle by automatic steering. An object of the present invention is to provide a driving support device capable of preventing or suppressing a situation that makes the user feel.

In order to achieve the above object, the following solution is adopted in the present invention. That is, as described in claim 1,
Forward obstacle detection means for detecting a forward obstacle;
Avoidance path generation means for generating an avoidance path for avoiding the front obstacle detected by the front obstacle detection means and passing a side of the front obstacle;
Steering control means for performing automatic steering so as to travel on the avoidance path generated by the avoidance path generation means;
With
The avoidance route generation means generates the avoidance route so that the degree of change of the landscape viewed from the driver through the windshield is small.
It is like that.

  According to the above solution, the avoidance route that avoids the front obstacle is generated so that the degree of change of the scenery viewed by the driver is small, so that the driving is performed as compared with the case where the scenery changes rapidly. The situation where a person feels dangerous can be prevented or suppressed.

A preferred mode based on the above solution is as described in claim 2 and the following. That is,
The avoidance path generating means generates the avoidance path so that the maximum value of the angle change rate of the optical flow indicating the flow of the landscape through the front window glass is reduced (corresponding to claim 2). In this case, the degree of change of the landscape can be grasped using a physical index called the optical flow angle change rate. In addition, the burden on the control system is smaller than when the degree of change in the landscape is detected from an image of the landscape itself.

  The avoidance path generation means generates the avoidance path so that the maximum value of the angle change rate of the optical flow is minimized (corresponding to claim 3). In this case, the effect corresponding to the first aspect is preferable in order to fully exhibit the effect.

  Compared to the case where the avoidance route generated by the avoidance route generation means travels on a comparative avoidance route having a sigmoid curve assumed to avoid the front obstacle, the first half of steering is earlier and the latter half Is set to be delayed (corresponding to claim 4). In this case, a more specific avoidance route to be generated is provided. In addition, since the steering in the first half of the avoidance route at the time of turning the steering wheel is performed early, the degree of change in the landscape at this time can be made relatively small, and the driver feels dangerous. This is preferable for further preventing or suppressing the situation.

  ADVANTAGE OF THE INVENTION According to this invention, when driving | running the avoidance path | route for avoiding a front obstacle by automatic steering, the situation which makes a driver | operator feel unnecessary danger can be prevented or suppressed.

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. The figure which shows selecting the coefficient e from which the maximum value of the angle change rate of an optical flow becomes the minimum. The figure which shows the difference of the lateral movement distance between the comparison avoidance path | route made into sigmoid curve shape, and the avoidance path | route by this invention. The figure which shows the relationship between the reciprocal of collision margin time, and the danger which a driver | operator feels comparing the case where it drive | works the comparison avoidance path | route made into sigmoid curve shape, and the avoidance path | route by this invention. 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 (avoidance route) for the host vehicle V to avoid the front pylon 21 is indicated by K in the figure. Although the avoidance route K of the host vehicle V will be described in detail later, generally, a steering wheel cutting operation is performed to the right from the straight traveling, and then a steering wheel switching operation is performed. It is set to go straight on the side (right side). 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 recognized by the driver when the vehicle V is automatically driven to travel along the avoidance route 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 the habit of moving the line of sight and the line of sight according to the change of the landscape, and it is possible to move the line of sight in that direction, especially paying attention to the newly appearing landscape It becomes a thing with high property.

  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 moving 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, generation of the avoidance route K will be described. First, when the forward distance from the host vehicle V is x and the lateral movement distance of the host vehicle V at that time (the movement distance in the right direction in FIG. 1) is y, for example, the following relationship (1) 2 is satisfied. Thus, an avoidance route K is generated. However, the direction of the host vehicle V is parallel to the travel path 11 at the start of steering and at the end of steering, and there is no overshoot for lateral movement.

y = ax ⁷ + bx ⁶ + cx ⁵ + dx ⁴ + ex ³ (1)
In the above equation (1), a to e are coefficients, respectively, and the coefficients a to d are determined according to the coefficient e.

  FIG. 6 shows the relationship between the angle change rate of the main optical flow and the coefficient e in the region α described above. The coefficient e is selected such that the angle change rate is minimized so that the angle change rate of the optical flow is smaller than a predetermined value set in advance. That is, by making the coefficient e different, the maximum value of the angular change rate of the optical flow that occurs until the front obstacle is avoided is changed, so that the maximum value of the angular change rate is not more than a predetermined value ( The coefficient e is selected (preferably to be minimal). Then, the coefficients a to d are determined based on the selected coefficient e.

  FIG. 7 shows the relationship between the forward distance from the host vehicle V and the lateral movement distance of the host vehicle V at that time. In FIG. 7, a curve connecting ▲ and a curve connecting ■ are each an avoidance path. A case where the avoidance path indicated by the display is an avoidance path according to the present invention, and the coefficient e in the equation (1) is selected so that the maximum value of the angle change rate of the optical flow is minimized. In addition, the avoidance route indicated by ■ is a comparative avoidance route determined as a sigmoid curve. As is clear from FIG. 7, the avoidance route according to the present invention is set so that the first half steering is earlier and the second half steering is slower than the comparative avoidance route.

  FIG. 8 is experimental data showing the difference in danger felt by the driver when traveling on the avoidance route according to the present invention and the comparison avoidance route. In FIG. 8, TTC (Time-To-Collision) in “reciprocal number of TTC” shown on the horizontal axis is a collision margin time, which is for the side pylon 22 shown in FIG. The larger the reciprocal of the collision margin time TTC, the shorter the arrival time to the pylon. In FIG. 8, “OF minimization path” is a case of an avoidance path according to the present invention, and “no OF consideration” is a case of a comparison avoidance path. As is clear from FIG. 8, when traveling on the avoidance route according to the present invention, the variation in danger is smaller and the degree of feeling danger is smaller than when traveling on the comparison avoidance route. It is understood that

  Next, a control example of the present invention in which the avoidance path is set so that the above-described angle change rate of the optical flow is minimized will be described with reference to FIGS. First, FIG. 9 shows an example of a control system of the present invention, and 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. 10 is a flowchart showing the 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. Thereafter, 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 YES in Q4, an avoidance route is generated in which the maximum value of the detected angular change rate of the optical flow is minimized in Q5. That is, the size of the coefficient e in the equation (1) is selected so that the maximum value of the angle change rate of the optical flow is minimized (see FIG. 6), and other coefficients a to d are determined according to the coefficient e. Thus, an avoidance route is generated based on the equation (1). Note that the optical flow is detected immediately before the generation of the avoidance route, and the situation in which the optical flow changes until it actually passes the side of the front obstacle is the current vehicle speed and the required lateral movement. The coefficient e is selected (estimated) based on the distance and the distance to the front obstacle, and the coefficient e is selected so that the calculated maximum value of the angular change rate of the optical flow is minimized.

  After Q5, in Q6, the vehicle V is automatically steered so that the host vehicle V travels on the avoidance route generated in Q5. In this automatic steering, as described with reference to FIG. 7, the first half steering is performed earlier and the second half steering is delayed as compared with the comparative avoidance path having a sigmoid curve. The fact that the first half of the steering on the avoidance route is earlier means that the rate of change in the angle of the optical flow is smaller than that in the case where it is delayed, and the degree to which the driver feels danger is reduced accordingly. This is also preferable.

  After Q6, it is determined in Q7 whether or not a forward obstacle has been avoided. If the determination in Q7 is NO, the process returns to Q6. If YES in Q7, normal automatic operation is restored in Q8.

  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. Expression (1) for generating the avoidance route is an example, and the avoidance route can also be generated by other methods. 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: avoidance route 11: travel route 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)

Forward obstacle detection means for detecting a forward obstacle;
Avoidance path generation means for generating an avoidance path for avoiding the front obstacle detected by the front obstacle detection means and passing a side of the front obstacle;
Steering control means for performing automatic steering so as to travel on the avoidance path generated by the avoidance path generation means;
With
The avoidance route generation means generates the avoidance route so that the degree of change of the landscape viewed from the driver through the windshield is small.
A driving support device characterized by that. In claim 1,
The driving assistance device, wherein the avoidance route generation means generates the avoidance route so that a maximum value of an angular change rate of an optical flow indicating a flow of scenery through the front window glass is reduced. In claim 2,
The avoidance route generation means generates the avoidance route so that the maximum value of the angle change rate of the optical flow is minimized. In any one of Claims 1 thru | or 3,
Compared to the case where the avoidance route generated by the avoidance route generation means travels on a comparative avoidance route having a sigmoid curve assumed to avoid the front obstacle, the first half of steering is earlier and the latter half The driving support device is set so that the steering of the vehicle is delayed.

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