JP7486657B2 - Rear monitoring device - Google Patents

Description

The present invention relates to a rear monitoring device for a vehicle, for example using millimeter wave radar.

A lane change assistance device that assists automobiles in changing lanes uses technology described in JP 2010-127908 A (Patent Document 1) to warn vehicles in adjacent lanes regardless of the road shape, such as straight or curved.

This patent document 1 states that "the lane in which the rear object is located is estimated by the other vehicle lane estimation unit based on the relative positional relationship between the vehicle's past driving position and the position of the rear object."

JP 2010-127908 A

However, in the technology described in Patent Document 1, when the vehicle changes lanes, the vehicle does not travel along the lane, so the lane of the object behind cannot be correctly estimated. This can result in a false alarm being issued to a vehicle further ahead in the lane change destination where an alarm is not required, or a failure to issue an alarm to a dangerous vehicle that is rapidly approaching from behind the lane change destination.

Therefore, the present invention aims to provide a rear monitoring device that can accurately estimate an object (moving body) approaching from behind even while changing lanes and output an appropriate warning to the driver.

In order to solve the above problem, one representative rear monitoring device of the present invention comprises a movement history acquisition unit that acquires the movement history of the host vehicle, a path estimation unit that estimates the future path of the host vehicle assuming that the host vehicle does not change course, and a monitoring range setting unit that, when the host vehicle starts to change course, sets a monitoring range for monitoring the presence of other moving objects based on the movement history of the host vehicle before it starts to change course and the estimated path.

According to the present invention, by estimating the position of the vehicle as if it had not changed lanes and setting the monitoring range based on that information, it is possible to properly estimate objects (moving bodies) approaching from behind even while changing lanes, thereby reducing false alarms and missed alarms while changing lanes.

Issues, configurations and effects other than those described above will become clear from the description of the embodiments below.

1 is a system configuration diagram showing the configuration of a rear warning system to which an embodiment of a rear warning device (rear monitoring device) of the present invention is applied; FIG. 2 is an image diagram of a vehicle changing lanes when the vehicle is equipped with a rear warning system to which the present invention is applied. 1 is an image diagram showing a state from before the start of a lane change to after the completion of the lane change when a rear warning system to which the present invention is applied is installed. 4 is a flowchart showing an embodiment of a processing procedure of a rear warning device (rear monitoring device) of the present invention. 13 is a diagram showing the movement amount and rotation angle at time t+1. FIG. 4 is an explanatory diagram showing an example of vehicle path estimation when traveling in a straight line; FIG. 4 is an explanatory diagram showing an example of vehicle travel path estimation when traveling along a curve. 10 is a flowchart showing a procedure for determining an alarm condition (S108). FIG. 13 is a diagram showing an example of this process at the time when a lane change is performed at time t and the current time is t+3. FIG. 13 is an image diagram of the warning necessity determination process (S116).

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In all drawings used to explain the embodiment, the same parts are designated by the same reference numerals, and repeated explanations may be omitted.

[System configuration]
FIG. 1 is a system configuration diagram showing the configuration of a rear warning system to which an embodiment of a rear warning device (rear monitoring device) according to the present invention is applied.

The rear warning system 50 in the illustrated embodiment is mounted on a vehicle (hereinafter also referred to as the host vehicle or the host vehicle) and is a system that monitors the rear of the vehicle and assists the driver in changing lanes by detecting other objects (moving bodies such as vehicles) that are rapidly approaching from behind the vehicle and sounding an alarm.

The rear warning system 50 of this embodiment has a millimeter wave radar 1, a steering angle sensor 2, a yaw rate sensor 3, a wheel speed sensor 4, a vehicle ECU 5, an alarm display LED 6, an alarm notification buzzer 7, and an ADAS ECU 8.

The millimeter wave radar 1 is composed of one or more millimeter wave radars for detecting objects present behind the vehicle. This millimeter wave radar 1 transmits radio waves to a specified range behind the vehicle and detects the relative position of objects behind the vehicle and their relative speed to the vehicle by receiving the reflected waves. For example, two radars are installed at different angles on the left and right sides of the rear of the vehicle.

In addition, in this embodiment, a millimeter wave radar is used as an external sensor device that recognizes and acquires external information around the vehicle, but other external sensor devices such as a LIDAR or ultrasonic sensor may also be used.

The steering angle sensor 2 and the yaw rate sensor 3 detect the steering angle (handle angle) and yaw rate of the vehicle, respectively. The wheel speed sensor 4 detects the vehicle speed by detecting the wheel speed pulses of the vehicle.

In this embodiment, the vehicle ECU 5 outputs left and right turn signal information of the vehicle to the ADAS ECU 8.

The alarm display LED 6 and alarm notification buzzer 7 are devices that notify the driver by display or sound when an alarm is issued, based on the alarm calculated by the ADAS ECU 8.

The ADAS ECU 8 is mainly configured as a computer including a CPU, RAM, ROM, etc., and in this example, is configured to include a rear warning device (rear monitoring device) 10. The rear warning device 10 of the ADAS ECU 8 inputs information about the vehicle itself (vehicle information) and determines whether or not an alarm should be issued.

[Configuration of rear warning device]
The rear warning device 10 of this embodiment has a movement history acquisition unit 11, an object detection unit 12, a lane change determination unit (course change determination unit) 13, a first warning determination processing unit 14, a second warning determination processing unit 15, and a warning issuing unit 16. The first warning determination processing unit 14 has a first warning range setting unit 141 and a first warning necessity determination unit 142, and the second warning determination processing unit 15 has a traveling path estimation unit 150, a second warning range setting unit 151, and a second warning necessity determination unit 152.

<Movement History Acquisition Unit>
In this example, the movement history acquisition unit 11 acquires vehicle movement history information relating to the movement history of the vehicle by calculating the amount of movement of the vehicle from the vehicle speed and rotation angle of the vehicle based on signals acquired from sensors mounted on the vehicle (steering angle sensor 2, yaw rate sensor 3, wheel speed sensor 4).

In addition, vehicle movement history information may be obtained using map information or navigation information of the vehicle, sensor information obtained from a sensor installed outside the vehicle, information obtained through vehicle-to-vehicle communication, or road-to-vehicle communication, etc.

<Object detection unit>
The object detection unit 12 detects the relative position and relative speed of an object behind the vehicle from the signal (external world information) acquired from the millimeter wave radar 1.

<Lane change judgment unit>
In this example, the lane change determination unit 13 determines the start and completion of a lane change (course change) of the host vehicle from left and right turn signal information (on/off operation information) output by the vehicle ECU 5 .

Note that the presence or absence of a lane change of the vehicle (and the associated estimation of the vehicle's position assuming no lane change, which will be described later) may be determined when the movement of the vehicle (more specifically, a departure from the current lane of the vehicle of a specified value or more) is detected based on the amount of change in the steering wheel angle, instead of or together with the information on the on/off operation of the turn signal. That is, for example, the start of a lane change of the vehicle (and the associated estimation of the vehicle's position assuming no lane change, which will be described later) may be determined at the first cycle when the turn signal is turned on, or when it is detected that the turn signal is turned on and/or that the vehicle has begun to leave the current lane of the vehicle (by a specified value or more) (for example, determined by the amount of change in the steering wheel angle).

<First warning determination processing unit (warning determination processing other than during lane change)>
The first warning determination processing unit 14 operates when the lane change determination unit 13 determines that the vehicle is not changing lanes, and performs warning determination processing for the vehicle not changing lanes. In this warning determination processing for the vehicle not changing lanes, the host vehicle movement history information acquired by the movement history acquisition unit 11 is used to determine whether there is a dangerous vehicle that is rapidly approaching the rear of the host vehicle when the host vehicle is traveling other than when changing lanes.

Therefore, the first warning determination processing unit 14 includes a first warning range setting unit 141 that uses the vehicle movement history information acquired by the movement history acquisition unit 11 to set a warning range (monitoring range) for monitoring the presence (entry) of other moving objects that are rapidly approaching the rear of the vehicle and issuing a warning, and a first warning necessity determination unit 142 that determines the presence or absence of other moving objects within the warning range and the necessity of a warning for those moving objects (i.e., moving objects that are included in the warning range and are subject to a warning). Note that the method for setting the warning range here is publicly known, so a detailed explanation will be omitted in this specification.

<Second warning determination processing unit (warning determination processing during lane change)>
The second warning determination processing unit 15 operates when the lane change determination unit 13 determines that the vehicle is changing lanes, and performs warning determination processing during lane change. In this warning determination processing during lane change, the travel path estimation unit 150 estimates the vehicle travel path information (described later), and determines whether there is a dangerous vehicle rapidly approaching from behind the vehicle using the vehicle movement history information acquired by the movement history acquisition unit 11 during the lane change of the vehicle and the vehicle travel path estimation information estimated by the travel path estimation unit 150. As described above, this processing is performed when the turn signal is on.

Therefore, the second warning determination processing unit 15 includes a path estimation unit 150 which estimates host vehicle path information (host vehicle position information) relating to the host vehicle's future path (host vehicle position) assuming that the host vehicle will not change lanes (from the lane change start point), a second warning range setting unit (monitoring range setting unit) 151 which uses the host vehicle movement history information and the host vehicle path estimation information to set a warning range (monitoring range) for monitoring the presence (entry) of other moving objects that are rapidly approaching from behind the host vehicle and issuing a warning, and a second warning necessity determination unit 152 which determines whether or not there are other moving objects within the warning range and whether or not a warning is necessary for those moving objects (i.e., moving objects that are included in the warning range and are subject to a warning).

The method of estimating vehicle path information by the path estimation unit 150, the method of setting the warning range by the second warning range setting unit 151, and the method of judgment by the second warning necessity judgment unit 152 will be explained later.

<Alarm issuing section>
When the first alarm determination processing unit 14 (its first alarm necessity judgment unit 142) or the second alarm determination processing unit 15 (its second alarm necessity judgment unit 152) judges that an alarm is necessary (i.e., there is a moving object that is the target of the alarm and is included in the alarm range), the alarm issuance unit 16 outputs an alarm command to issue an alarm to the alarm display LED 6 and the alarm notification buzzer 7.

Figure 2 is an image diagram showing a lane change when a vehicle is equipped with a rear warning system incorporating the present invention.

This is an example in which the vehicle 20 changes lanes to the center lane while traveling in the left lane of a three-lane road. The dashed line in the figure represents the travel trajectory of the vehicle 20. × indicates the movement history of the vehicle 20 before the lane change start, and ▲ indicates the position (travel path) of the vehicle 20 when it is assumed that the vehicle does not change lanes from the lane change start position. From the movement history of the vehicle 20 before the lane change start and the position (travel path) of the vehicle 20 when it is assumed that the vehicle does not change lanes, the warning range 21 is determined to be the center lane of the lane change destination of the vehicle 20 (second warning range setting unit 151) (details will be explained later). The other vehicle 25 is a dangerous vehicle (another moving body) rapidly approaching the vehicle 20, and is in the warning range 21 (second warning necessity determination unit 152), so a warning is output (warning issuing unit 16). The other vehicle 26 is a vehicle that exists in the lane further ahead of the lane change (the right lane of a three-lane road), and exists outside the warning range 21, so no warning is output.

Figure 3 is an image diagram of a lane change performed by a vehicle equipped with a rear warning system according to the present invention, from before the lane change begins to after the lane change is completed. Note that Figure 3 only describes the warning range for the rear and right side (right rear lane) of the vehicle 20, but the same applies to the warning range for the rear and left side (left rear lane) of the vehicle 20.

As in FIG. 2, this is an example in which the vehicle 20 changes lanes to the center lane while traveling in the left lane of a three-lane road. Before the lane change starts, the alarm range 21 is set to the lane adjacent to the current lane of the vehicle 20 (center lane) using only the movement history of the vehicle 20 before the lane change started acquired by the movement history acquisition unit 11 (first alarm range setting unit 141) (see the left diagram of FIG. 3). When it is determined that the vehicle is changing lanes (starting a lane change) using the turn signal on as a trigger (lane change determination unit 13), as in FIG. 2, the alarm range 21 is set to the lane of the vehicle 20 to which the lane change is to be made (center lane) using the movement history of the vehicle 20 before the lane change started acquired by the movement history acquisition unit 11 and the position (traveling path) of the vehicle 20 assuming that the lane change is not to be made (second alarm range setting unit 151) (see the center diagram of FIG. 3). When it is determined that the lane change has ended (completed) by triggering the turn signal off (lane change determination unit 13), the movement history of the vehicle 20 acquired by the movement history acquisition unit 11 is not used for a certain period after completion, since the movement history of the vehicle 20 includes lane change during lane change and is not along the lane, and the alarm range 21 is fixed (fixed to the alarm range 21 set in the center lane, which is the driving lane to which the vehicle 20 will change lanes) (for example, rectangular) and a judgment is made (second alarm range setting unit 151). After that (in other words, after a certain period of time has passed after completion), after the movement history of the vehicle 20 has been sufficiently acquired, the alarm range 21 (set to the adjacent lane (right lane) of the driving lane of the vehicle 20 after the lane change is completed) based on the movement history of the vehicle 20 acquired by the movement history acquisition unit 11 after the lane change is completed is used (first alarm range setting unit 141) (see the right diagram in FIG. 3).

[Processing flow of rear warning device]
4 is a flowchart showing an embodiment of the processing procedure of the rear warning device according to the present invention. This processing is performed within the ADAS ECU 8. This processing is started when the vehicle exceeds a certain speed while traveling. To summarize this processing, in S103, the presence or absence of a turn signal (on/off operation information) is determined, and if the turn signal is present, it is determined that the vehicle is changing lanes, and a warning determination process for when the vehicle is changing lanes (S105 to S108) is performed. If the turn signal is not present, it is determined that the vehicle is not changing lanes (driving in the same driving lane), and a warning determination process for when the vehicle is not changing lanes (S104) is performed.

The details of the process are explained using the flowchart in Figure 4.

<Movement History Information Acquisition Process (Movement History Acquisition Unit 11)>
In S101, the movement amount of the vehicle (corresponding to the vehicle movement history information) is calculated. As shown in Fig. 5, when the movement amount and rotation angle at time t+1 are (Δxt ₊₁ , Δyt ₊₁ ) and Δθt ₊₁ , (Δxt ₊₁ , Δyt ₊₁ ) can be calculated by the following formula.

Here, Δt is the processing time [s] for one cycle, and Vs [m/s] and Δθ _t+1 [rad] are the vehicle speed and rotation angle of the host vehicle based on the signals obtained from the sensors.

<Object detection process (object detection unit 12)>
In S102, an object (hereinafter also referred to as a target object) behind the vehicle is detected by the millimeter wave radar 1, and the relative position and relative speed of the object are obtained. The relative position of the detected object is converted into a coordinate system centered on the front end of the vehicle.

<Lane Change Determination Processing (Lane Change Determination Unit 13)>
In S103, it is determined whether the turn signal is on in the current cycle. If the turn signal is off (more specifically, after a certain time has passed since the turn signal was turned off), it is determined that the vehicle is not changing lanes, and an alarm determination process other than for lane changing is performed in S104. If the turn signal is on (more specifically, until a certain time has passed since the turn signal was turned off), it is determined that the vehicle is changing lanes, and an alarm determination process during lane changing in S105 to S108 is started.

<Warning Determination Processing Other Than During Lane Change (First Warning Determination Processing Unit 14, Warning Issuance Unit 16)>
In S104, a warning determination process is performed for a state other than when changing lanes. At that time, the vehicle movement history information in a coordinate system centered on the current vehicle tip is calculated from the movement amount obtained in S101. In addition, using the calculated vehicle movement history information, a warning range (monitoring range) for monitoring the presence (entry) of another moving object that is rapidly approaching the rear of the vehicle and issuing a warning is set (in the adjacent lanes), and the presence or absence of another moving object in the warning range and the necessity of a warning for that moving object (i.e., a moving object that is a target of a warning and is included in the warning range) are determined. When it is determined that a warning is necessary (i.e., there is a moving object that is a target of a warning and is included in the warning range), the warning issuing unit 16 is instructed to output a warning command for issuing a warning to the warning display LED 6 and the warning notification buzzer 7.

<Warning Determination Processing During Lane Change (Second Warning Determination Processing Unit 15, Warning Issuance Unit 16)>
<<Path Estimation Processing (Path Estimation Unit 150)>>
In S105, it is determined whether or not it is the first cycle after the turn signal is turned on. If it is the first cycle after the turn signal is turned on, S106 is carried out, and if not, S106 is skipped and the process proceeds to S107.

In S106, vehicle position information (vehicle travel path information) is estimated assuming that the vehicle will not change lanes (in other words, will continue to travel in the lane in which it was traveling when the lane change was initiated).

<Estimating vehicle path using vehicle model>
The above estimation is performed by estimating the vehicle's travel path using a vehicle model including vehicle information. The vehicle's travel path estimation is performed by different processes when driving in a straight line and when driving on a curve. This process is determined, for example, by the steering angle and yaw rate. FIG. 6 is an example of the vehicle's travel path estimation when driving in a straight line. In the figure, points after P _t+1 are estimated. The travel path P _i (Xi, Yi) [m] of the vehicle when it is assumed that the vehicle did not change lanes while driving in a straight line can be calculated by the following formula.

where Vs is the vehicle speed [m/s], and the subscript i indicates which (how many cycles ahead) the prediction result is. For example, if the current time is t, then P _t+3 represents the coordinates of the prediction result for the t+3 cycle. Time is the prediction time; for example, if one cycle is 0.5 s and prediction results for up to 10 s ahead are used, the value obtained by adding 0.5 s from 0.5 s to 10 s is used.

Figure 7 shows an example of estimating the vehicle's path when traveling around a curve. In the figure, points after P _t+1 are estimated. If it is assumed that the vehicle does not change lanes while traveling around a curve, the path P _i (Xi, Yi) [m] of the vehicle can be calculated using the following formula:

The subscript i indicates the number (cycle ahead) of the predicted result. For example, if the current time is t, P _t+3 represents the coordinates of the predicted result for the t+3 cycle. The turning radius ρ [m] and the rotation angle θ [rad] can be calculated using the following formula.

where Vs is the vehicle speed [m/s], ω is the yaw rate [rad/s], and Time is the predicted time.

<Estimating vehicle path by extrapolating point clouds of movement history>
The estimation of the host vehicle position (host vehicle travel path) in the case where the host vehicle does not change lanes in S106 may be performed by extrapolating from the point cloud of the host vehicle's movement history.

The vehicle path estimation using the extrapolation method performs different processing when traveling in a straight line and when traveling on a curve. The processing is determined, for example, based on the steering angle and yaw rate. The vehicle path P _i (Xi, Yi)[m] of the vehicle when it is assumed that the vehicle does not change lanes while traveling in a straight line is calculated using the same method as the method using the vehicle model described above.

An example of estimation by extrapolation when driving around a curve will be described with reference to Figure 7. In the figure, points after Pt ₊₁ are estimated. When driving around a curve, extrapolation is performed using values of the steering angle equal to or greater than a reference value in the movement history of the vehicle.

The variables a1 to a3 that minimize the above equation are found. In this case, (x, y) are the coordinates [m] of the movement history before the lane change. By solving the above optimization problem, the equation of the circle in the Cartesian coordinate system that passes through the movement history before the lane change is obtained.

In this case, it is a circle with radius a3 [m] centered at (a1, a2) [m].

The Cartesian coordinate system equation is converted to a polar coordinate system to obtain the estimated coordinates P _i (Xi, Yi).

The subscript i indicates the number (cycle ahead) of the predicted result. θ [rad] is calculated using the following formula.

Where Vs is the vehicle speed [m/s]. Time is the prediction time. For example, if one cycle is 0.5 seconds and prediction results for up to 10 seconds ahead are used, the value obtained by adding 0.5 seconds from 0.5 seconds to 10 seconds is used.

In this way, by extrapolating from the point cloud of the vehicle's movement history before changing lanes, it is possible to estimate the vehicle's future position (vehicle travel path) assuming that the vehicle does not change lanes from the vehicle's movement history information, even without using the yaw rate sensor 3.

In S107, the movement history (vehicle movement history information) and the point cloud of the vehicle position (vehicle travel path information) assuming no lane change are moved and rotated into a coordinate system centered on the current vehicle front end. At time t+1, this is calculated using the movement amount (Δx _t+1 , Δy _t+1 ) from t to t+1 and the rotation angle Δθ _t+1 using the following formula:

In S108, an alarm condition determination is performed. Figure 8 is a flowchart showing the processing steps for determining the alarm condition (S108).

In the loop processing of S110 to S119, the processing up to S118 is repeated for the number of targets detected by the millimeter wave radar 1 (S102).

<<Warning Range Setting Process (Second Warning Range Setting Unit 151)>>
In S111, a point where the y-coordinate value Sy of the target S detected by the millimeter wave radar 1 satisfies Yk-1<Sy and Sy<Yk is searched for. FIG. 9 is a diagram showing an example of this process when the vehicle changes lanes to the right at time t and the current time is t+3. A search is performed for the target S on the right side, which is the lane change direction, from the movement history P _t-7 to P _t-1 before the lane change starts and the vehicle positions P _t to P _t+2 assuming no lane change. In this example, the y-coordinate value Yt-2 of the movement history P _t-2 and the y-coordinate value Yt- _{3 of the movement history P t} -3 satisfy Yt-3<Sy and Sy<Yt-2, so P _t-2 and P _t-3 are the search results.

In S112, it is determined whether a point exists as a result of the search in S111. If it exists, it is determined that the point may be subject to an alarm, and the process proceeds to S113. If it does not exist, it is determined that the point is not subject to an alarm, and the process skips steps S113 to S118.

In S113, the equation _Lk of the straight line connecting Pk _-1 and _Pk , which are the search results, is found. When the equation _Lk is pX+qY+r=0, p, q, and r are found by the following equations.

In S114, the distance (position) d between the equation _Lk of the straight line obtained in S113 (corresponding to the movement history Pt _-7 to Pt _-1 before the start of the lane change and the vehicle positions _Pt to Pt ₊₂ assuming no lane change) and the target S is obtained. When the target S is (Sx, Sy), the distance d is obtained by the following equation.

In S115, it is determined how many lanes the current lane change involves (i.e., the number of lanes to be changed), and a determination threshold value dTH including a lower limit dTH1 and an upper limit dTH2 is set based on the determination result. The method for determining the number of lanes to be changed is, for example, based on the lane change time (more specifically, the elapsed time from the start of the lane change) or the steering angle. For example, in the case of a lane change of one lane, the lower limit dTH1 and upper limit dTH2 are determined as follows, assuming that the width Lv [m] of the host vehicle is the lane change, based on the determination result of the number of lanes to be changed:

In this formula, the lower limit value dTH1 means that the warning range is 0.5 m away from the side of the vehicle, and the upper limit value dTH2 means that the warning range is 0.5 m away from the side of the vehicle (i.e., 3 m away from the lower limit value dTH1).

On the other hand, based on the result of the determination of the number of lanes to be changed, in the case of a lane change involving two lanes, the lower limit value dTH1 and the upper limit value dTH2 are determined as follows.

In this formula, the lower limit dTH1 means that the warning range extends from 0.5 m away from the side of the vehicle to one lane (one lane is 3 m) ahead, and the upper limit dTH2 means that the warning range extends from the lower limit dTH1 to another 3 m. The range can also be expanded in a similar way when changing lanes on a road with three or more lanes.

Note that the values of 0.5m and 3m are just examples, and may be fixed values that match the road environment on which the vehicle is traveling, or may be variable values that can be variably set depending on the road environment on which the vehicle is traveling.

As a result, an alarm range (monitoring range) determined by the search results Pk _-1 and _Pk (corresponding to the y coordinate) and a judgment threshold dTH (corresponding to the x coordinate) including a lower limit dTH1 and an upper limit dTH2 set according to the number of lanes to be changed is set to the driving lane behind the host vehicle during the lane change. Note that the detection range of the millimeter wave radar 1 as the external sensor device is set in advance so that such an alarm range (monitoring range) can be set to the driving lane of the lane to be changed.

<<Warning Necessity Determination Process (Second Warning Necessity Determination Unit 152)>>
In S116, it is determined whether d found in S114 satisfies dTH1<d and d<dTH2 (whether it is included within the determination threshold dTH according to the number of changed lanes). FIG. 10 is an image diagram of the process of S116, and is an enlarged view of Pt _-2 , Pt _-3 , and the vicinity of the target S in FIG. 9. In this example, d is the distance between _Lt-2 and the target S. The lower limit value dTH1 and the upper limit value dTH2 found in S115 are the distance from _Lk ( _Lt-2 in this example) like d. If the condition of S116 is satisfied, it is determined that the target S is within the warning range, and S117 is performed. If the condition of S116 is not satisfied, it is determined that the target S is not a warning target, and S117 and S118 are skipped.

In S117, it is determined whether the speed of the target S satisfies the warning conditions. Based on the relative speed and position calculated from the millimeter wave radar 1, the estimated time of collision with the vehicle is calculated, and if the calculated estimated collision time is less than a specified value, the warning conditions are met and the process moves to S118. If the calculated estimated collision time is greater than the specified value and does not satisfy the warning conditions, the target S is not a target for warning and S118 is skipped.

S116 and S117 make it possible to determine whether another moving object (vehicle, etc.) that is rapidly approaching the vehicle from behind while changing lanes is present within the set alarm range and whether an alarm needs to be issued for that moving object.

In S118, the alarm issuing unit 16 is instructed to output an alarm command to issue an alarm to the alarm display LED 6 or the alarm notification buzzer 7. Methods for outputting an alarm command include outputting an alarm command to notify the driver via the alarm display LED 6, and outputting an alarm command to warn the driver using the alarm notification buzzer 7 when the risk is higher.

<Action and effect>
As described above, the rear warning device (rear monitoring device) 10 of this embodiment includes a movement history acquisition unit 11 that acquires the movement history of the host vehicle, a path estimation unit 150 that estimates the future path of the host vehicle (host vehicle position) on the assumption that the host vehicle will not change course (change lanes), a second alarm range setting unit (monitoring range setting unit) 151 that sets an alarm range (monitoring range) for monitoring the presence of other moving objects (other moving objects rapidly approaching from behind the host vehicle) when the host vehicle starts to change course, based on the movement history of the host vehicle before it started to change course and the estimated path of travel (when the host vehicle starts to change course), and an alarm issuance unit 16 that issues an alarm when another moving object is included in the alarm range (monitoring range).

In addition, the path estimation unit 150 estimates the path of the vehicle using path estimation from vehicle information before the vehicle changes course, or estimates the path of the vehicle by extrapolating from a point cloud of the movement history of the vehicle before the vehicle changes course.

According to the rear warning device (rear monitoring device) 10 of this embodiment, even during lane changing, the warning range is determined based on the movement history of the vehicle and the vehicle's position if it is assumed that the lane change would not occur (in other words, the position of the vehicle if it was assumed that the lane change would not occur is estimated and the warning range for the lane ahead is set based on that information), so that objects (moving bodies) approaching from behind can be accurately estimated even during lane changing, reducing false and missed warnings during lane changing.

In the above-described embodiment, the first alarm determination processing unit 14 (first alarm range setting unit 141, first alarm necessity determination unit 142) which performs alarm determination processing other than when changing lanes, and the second alarm determination processing unit 15 (pathway estimation unit 150, second alarm range setting unit 151, second alarm necessity determination unit 152) which performs alarm determination processing during lane changes are configured as separate components (separate functional blocks). However, the first alarm determination processing unit 14 and the second alarm determination processing unit 15 may be combined into a single functional block, and different processing (alarm determination processing other than when changing lanes, alarm determination processing during lane changes) may be performed within that functional block depending on (determining) whether or not the host vehicle is changing lanes.

In addition, in the above-mentioned embodiment, an example has been described in which an alarm command to issue an alarm is output to the alarm display LED 6 and the alarm notification buzzer 7 when it is determined that there is a moving object that is a target for the alarm within the set alarm range. However, it goes without saying that this embodiment may also be used for autonomous driving/driving assistance in which, instead of or in addition to an alarm to the driver by the alarm display LED 6 and the alarm notification buzzer 7, the above-mentioned alarm range is used as a monitoring range for monitoring moving objects approaching from behind, and when it is determined that there is a moving object that is a target for the alarm within the monitoring range, the vehicle is automatically controlled to avoid a collision with the moving object.

In addition, in the above-described embodiment, the rear warning device (rear monitoring device) 10 is included (built into) the ADAS ECU 8, which is a control device mounted on the vehicle, but it goes without saying that some or all of the configurations, functions, processing units, processing means, etc. of the rear warning device (rear monitoring device) 10 may be included and integrated into an external sensor device that recognizes and acquires external information around the vehicle, such as a millimeter wave radar 1.

The present invention is not limited to the above-mentioned embodiment, and various modifications are included. For example, the above-mentioned embodiment has been described in detail to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the configurations described. In addition, it is possible to replace a part of the configuration of a certain embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of a certain embodiment. In addition, it is possible to add, delete, or replace other configurations with respect to a part of the configuration of each embodiment. In addition, each of the above-mentioned configurations, functions, processing units, processing means, etc. may be realized in hardware by designing a part or all of them as an integrated circuit, for example. In addition, each of the above-mentioned configurations, functions, etc. may be realized in software by a processor interpreting and executing a program that realizes each function. Information such as programs, tables, files, etc. that realize each function can be placed in a memory, a recording device such as a hard disk or SSD (Solid State Drive), or a recording medium such as an IC card, SD card, or DVD.

1...Millimeter wave radar, 2...Steering angle sensor, 3...Yaw rate sensor, 4...Wheel speed sensor, 5...Vehicle ECU (Blinker information), 6...Alarm display LED, 7...Alarm notification buzzer, 8...ADAS ECU, 10...Rear warning device (rear monitoring device), 11...Movement history acquisition unit, 12...Object detection unit, 13...Lane change judgment unit (Course change judgment unit), 14...First alarm judgment processing unit (alarm judgment processing other than during lane change), 141...First alarm range setting unit, 142...First alarm necessity judgment unit, 15...Second alarm judgment processing unit (alarm judgment processing during lane change), 150...Route estimation unit, 151...Second alarm range setting unit (monitoring range setting unit), 152...Second alarm necessity judgment unit, 16...Alarm issuing unit, 20...Own vehicle, 21...Alarm range (monitoring range), 25...Other vehicle (alarm present), 26...Other vehicle (no alarm present), 50...Rear warning system

Claims (13)

A movement history acquisition unit that acquires a movement history of the host vehicle;
a course estimation unit that estimates a future course of the host vehicle on the assumption that the host vehicle will not change course;
and a monitoring range setting unit that, when the vehicle starts to change course, sets a monitoring range for monitoring the presence of other moving objects based on the movement history of the vehicle before it starts to change course and the estimated traveling path. The rear monitoring device as described in claim 1, further comprising an alarm issuing unit that issues an alarm if another moving object is included in the monitoring range. The rear monitoring device described in claim 1, wherein the path estimation unit estimates the path of the vehicle using path estimation from vehicle information before the vehicle changes course. The rear monitoring device of claim 1, wherein the path estimation unit estimates the path of the vehicle by extrapolating from a point cloud of the movement history of the vehicle before the vehicle changes course. A lane change determination unit that determines whether the vehicle has started to change lane,
2. The rear monitoring device according to claim 1, wherein the lane change determination unit determines that the host vehicle has started to change lane when at least one of a turn signal of the host vehicle is on or when the host vehicle starts to leave a current lane of the host vehicle. The rear monitoring device according to claim 1, wherein the path estimation unit estimates the path of the vehicle when the vehicle starts to change course. The rear monitoring device according to claim 1, wherein the travel path estimation unit estimates the travel path of the host vehicle when at least one of the following occurs: the turn signal of the host vehicle is on, or the host vehicle starts to leave the current lane of the host vehicle. The monitoring range setting unit is
When another moving object is detected behind the vehicle,
A movement history of the host vehicle before the start of the lane change and a distance of the other moving object to the estimated traveling path are obtained;
The rear monitoring device according to claim 1 , wherein the monitoring range is determined by setting a determination threshold according to a movement history of the host vehicle before the lane change is started and a number of lanes into which the vehicle has changed with respect to the estimated traveling path. The rear monitoring device of claim 8, wherein the monitoring range setting unit sets a judgment threshold according to the number of lanes to be changed based on at least one of the elapsed time since the host vehicle started to change course or the steering angle of the host vehicle. The monitoring device further includes an alarm issuing unit that issues an alarm when another moving object is included in the monitoring range,
The rear monitoring device according to claim 8 , wherein the alarm issuing unit issues an alarm when the distance to the other moving object is within a determination threshold value according to the number of changed lanes. The monitoring range setting unit is
Before the host vehicle starts to change course, the monitoring range is set to a lane adjacent to a current driving lane of the host vehicle based on a movement history of the host vehicle before the start of the lane change;
When the vehicle starts to change course, the monitoring range is set to a driving lane of a destination of the vehicle based on a movement history of the vehicle before the course change start and the estimated traveling path;
2. The rear monitoring device according to claim 1, wherein, when the host vehicle has completed the lane change, the monitoring range is set to a lane adjacent to the lane in which the host vehicle is traveling after the lane change is completed, based on a movement history of the host vehicle after the lane change is completed. The monitoring range setting unit is
12. The rear monitoring device according to claim 11, wherein, when the host vehicle has completed a lane change, the monitoring range set in the driving lane of the host vehicle's lane change destination is used for a certain period of time after the completion, and after the certain period of time has elapsed after the completion, the monitoring range is set to a lane adjacent to the driving lane of the host vehicle after the lane change is completed, based on a movement history of the host vehicle after the lane change is completed. The rear monitoring device according to claim 1, wherein the rear monitoring device is included in a control device mounted on the vehicle, or is included in an external sensor device that recognizes external information of the vehicle.

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