Collision avoidance assistance device

Abstract

The present application provides a collision avoidance assistance device that suppresses excessive or sudden work of braking in collision avoidance assistance for an object traveling on a lane orthogonal to the host vehicle (a road crossing the host vehicle), thereby improving functionality and usability. A predicted time until the host vehicle reaches a collision prediction point when the host vehicle is decelerated at a prescribed deceleration or braking force, i.e., a collision prediction point arrival time, is calculated. A braking work determination threshold is changed (increased or decreased) based on a predicted time required for the object to pass through a predicted intersection area (predicted intersection area) between a predicted travel path of the object (object predicted travel path) and a predicted travel path of the host vehicle (host vehicle predicted travel path), i.e., a predicted passing time, and the collision prediction point arrival time.

Description

Technical Field

[0001] This invention relates to a collision avoidance assist device that assists in driving a vehicle to avoid collisions with surrounding objects or to mitigate the damage from such collisions. Background Technology

[0002] As an example of a collision avoidance assist device at an intersection, there is the technology described in Patent Document 1. In the collision avoidance assist device described in Patent Document 1, the braking is performed at a position where the vehicle can stop without entering the intersection, based on the time remaining until a collision with an object (object) that is predicted to collide with the vehicle, i.e., the collision time remaining. [Existing Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-179729 Summary of the Invention [The problem the invention aims to solve]

[0004] When braking is applied at a position where the vehicle can stop without entering the intersection, as is the case with the collision avoidance assist device described above, based on the remaining time before the collision, the distance required to stop increases as the vehicle's speed increases. Therefore, the vehicle brakes at a position far away from the object where a collision is predicted.

[0005] However, as the distance between the vehicle and the object increases, the sensor's accuracy in recognizing the object and predicting the paths of both the vehicle and the object decreases, as does its accuracy in predicting whether a collision will occur. This leads to situations where sudden braking over-works, causing annoyance and burden to the driver, thus presenting problems in functionality and usability.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide a collision avoidance assist device that suppresses excessive or sudden braking in collision avoidance assist for objects traveling in a lane orthogonal to the vehicle (road intersecting the vehicle), thereby improving functionality and usability. [Technical means to solve the problem]

[0007] To achieve the above objectives, the present invention is configured as follows: A collision avoidance assist device calculates the predicted path of its own vehicle and the predicted path of an object existing on a road intersecting the vehicle. Based on the predicted path of the vehicle and the predicted path of the object, it calculates the remaining time of collision between the vehicle and the object, and the predicted collision location. If the remaining time of collision or the distance traveled by the vehicle within the remaining time of collision is below a braking action threshold, the device decelerates the vehicle with a predetermined deceleration or braking force to avoid a collision with the object. The collision avoidance assist device is characterized by calculating the predicted time (i.e., the collision prediction location arrival time) until the vehicle reaches the predicted collision location when the vehicle is decelerated with the predetermined deceleration or braking force. The braking action threshold is adjusted based on the estimated time required for the object to pass through the intersection area of ​​the predicted path of the object and the predicted path of the vehicle (i.e., the predicted passage time) and the collision prediction location arrival time. [The effects of the invention]

[0008] According to the present invention, in collision avoidance assistance for objects traveling in lanes orthogonal to the vehicle (roads intersecting the vehicle), excessive or sudden braking is suppressed, thereby improving functionality and usability.

[0009] Other issues, components, and effects not mentioned above will be clarified through the following description of the implementation method. Attached Figure Description

[0010] Figure 1 This is an example of a schematic configuration diagram of a vehicle equipped with an embodiment of the collision avoidance assist device of the present invention. Figure 2 This is an example of a functional block diagram of one embodiment of the collision avoidance assist device of the present invention. Figure 3 A flowchart for the alarm braking operation determination unit in cases where the threshold for determining whether braking is in operation has been shortened. Figure 4 This is an example of how the predicted transit time is calculated based on the predicted overlap rate. Figure 5 An example of the changes in the remaining collision time, the lateral position of the object, and the longitudinal position of the object over time, in order to shorten the threshold used to determine whether braking is present. Figure 6 A flowchart for the alarm braking operation determination unit in cases where the threshold for determining whether braking is in operation has been extended. Figure 7This is an example of the changes in the remaining collision time, the lateral position of the object, the longitudinal position of the object, and the deceleration of the vehicle itself over time, given that the threshold for determining whether braking has been applied has been extended. Figure 8 This is a graph illustrating the relationship between the threshold used to determine whether braking has occurred (braking operation determination threshold or collision remaining time travel distance threshold) and the distance traveled by the vehicle within the remaining time of the collision. Detailed Implementation

[0011] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Furthermore, in all the drawings used to illustrate the embodiments, parts having the same function are labeled with the same symbol, and sometimes repeated descriptions are omitted.

[0012] Figure 1 A vehicle equipped with one embodiment of the collision avoidance assist device of the present invention is shown in a schematic diagram. The collision avoidance assist device 11 is mounted on the vehicle (the vehicle itself) 10 and assists in the driving operation of the vehicle 10 (in this example, it is a collision avoidance assist for objects traveling in a lane orthogonal to the vehicle (a road intersecting the vehicle itself)).

[0013] The vehicle 10 of the illustrated embodiment consists of a front camera 2F (hereinafter sometimes referred to as camera 2) mounted at the front of the vehicle, a radar 3, a right front wheel speed sensor 5FR for detecting the wheel speed of the right front wheel 4FR, a right rear wheel speed sensor 5RR for detecting the wheel speed of the right rear wheel 4RR, a left rear wheel speed sensor 5RL for detecting the wheel speed of the left rear wheel 4RL, a left front wheel speed sensor 5FL for detecting the wheel speed of the left front wheel 4FL, a steering angle sensor 6, a yaw rate sensor 7, an instrument panel 8, a buzzer 9, a collision avoidance assist device 11, and a braking control device 12.

[0014] The forward camera 2F is equipped with a lens and an image sensor, and is appropriately configured to capture the surrounding environment of the vehicle 10. The image captured by the forward camera 2F is sent to the collision avoidance assist device 11 for image processing. In the collision avoidance assist device 11, the object category of the objects (hereinafter referred to as objects) around the vehicle 10 is determined based on the image captured by the forward camera 2F. Examples of object categories include cars, bicycles, pedestrians, two-wheeled vehicles, roads, lanes such as white or yellow lines, traffic lights, traffic signs, obstacles, etc. In this embodiment, one camera 2 is configured to capture the surrounding environment of the vehicle 10, but multiple cameras can also be configured. The camera 2 can be a monocular camera or a stereo camera, and the type of camera and the functions equipped in the camera can be changed as needed.

[0015] Radars 3 are positioned at the four corners of the vehicle 10. Each radar 3 emits electromagnetic waves and receives reflected waves from surrounding objects, thereby determining the position and speed of objects around the vehicle 10 and sending the results to the collision avoidance assist device 11. Radars 3 can be millimeter-wave radar or lidar, or ultrasonic sensors can be used instead of radar. Furthermore, multiple sensor types can be combined to determine the speed and position of objects.

[0016] In this embodiment, as an example of a means of obtaining information about objects around the vehicle 10, a camera 2 and a radar 3 are used in combination. However, a lidar may be used instead of a radar 3, or multiple sensors may be used.

[0017] The vehicle 10 has a right front wheel 4FR, a right rear wheel 4RR, a left rear wheel 4RL, and a left front wheel 4FL positioned around its front, rear, left, and right sides. Each of these wheels 4FR, 4RR, 4RL, and 4FL is equipped with a right front wheel speed sensor 5FR, a right rear wheel speed sensor 5RR, a left rear wheel speed sensor 5RL, and a left front wheel speed sensor 5FL. Each wheel speed sensor 5FR, 5RR, 5RL, and 5FL detects the wheel speed and sends it to the collision avoidance assist device 11. The collision avoidance assist device 11 calculates the speed of the vehicle 10 based on the wheel speed information. Hereinafter, unless otherwise specified, the right front wheel 4FR, right rear wheel 4RR, left rear wheel 4RL, and left front wheel 4FL will be referred to as wheel 4, and the right front wheel speed sensor 5FR, right rear wheel speed sensor 5RR, left rear wheel speed sensor 5RL, and left front wheel speed sensor 5FL will be referred to as wheel speed sensor 5.

[0018] The steering angle sensor 6 is a sensor that detects the rotation angle (steering angle) of the steering wheel of the vehicle 10. The steering angle detected by the steering angle sensor 6 is sent to the collision avoidance assist device 11.

[0019] Yaw rate sensor 7 detects the yaw rate of its own vehicle 10, and the yaw rate detected by yaw rate sensor 7 is sent to collision avoidance assist device 11.

[0020] For example, when the collision avoidance assist device 11 determines that there is a high probability of a collision between its own vehicle 10 and the object, the instrument panel 8 displays a warning image to inform the driver of this high probability of collision. In this embodiment, the instrument panel 8 is provided as an example of a means of displaying the warning image, but it may also be part of a car navigation system instead of the instrument panel 8, or a head-up display may be used to display the image.

[0021] The buzzer 9 sounds, for example, when the collision avoidance assist device 11 determines that there is a high probability of a collision between its own vehicle 10 and the object, as a warning sound to inform the driver of this high probability of a collision. In this embodiment, the buzzer 9 is provided as an example of a means of sounding the warning sound, but it may also be part of the car navigation system instead of the buzzer 9, or a speaker may be used to sound the warning sound.

[0022] The collision avoidance assist device 11 is configured to perform collision avoidance assist actions to avoid collisions between the vehicle 10 and objects or to mitigate collision damage. The collision avoidance assist device 11 is configured to output control signals for activating the instrument cluster 8, the buzzer 9, and the brake control device 12 based on information received from the aforementioned multiple sensors. In this embodiment, the collision avoidance assist device 11 is configured, for example, as an ECU (Electric Control Unit) mounted on the vehicle 10, to assist in any or all of the following operations to achieve collision avoidance assist actions: displaying a warning image on the instrument cluster 8, sounding a warning sound on the buzzer 9, or automatically activating the brakes via the brake control device 12.

[0023] The brake control device 12 controls the braking device (not shown) of the vehicle 10. The brake control device 12 is a component that can adjust the braking force generated by the braking device according to the control signal output from the collision avoidance assist device 11, and includes, for example, brake actuators such as hydraulic pumps and valve units.

[0024] Figure 2 Showing Figure 1 The collision avoidance assist device 11 shown is composed of internal functional blocks. These functional blocks are implemented by hardware, software, or a combination thereof. Each function of the collision avoidance assist device 11 is implemented by a processor such as a CPU (Central Processing Unit) executing programs stored in ROM (Read Only Memory). RAM (Random Access Memory) stores data including intermediate data from the calculations of the programs executed by the processor.

[0025] like Figure 2 As shown, the collision avoidance assist device 11 basically includes an object information integration and processing unit 201, a vehicle information calculation unit 202, an alarm braking operation determination unit 203, a collision alarm calculation unit 204, and a braking indication value calculation unit 205.

[0026] In the object information integration and processing unit 201, the form and coordinate system of object categories such as vehicles, bicycles, and pedestrians, as well as the current position and speed information of the object, obtained from the camera 2 and radar 3, are unified. Regarding the coordinate system used in this embodiment, as an example, the current position (hereinafter referred to as the current position of the object) and the speed (hereinafter referred to as the speed of the object) are determined with the center of the front end of the vehicle 10 as the origin, the entire length of the vehicle 10 as the longitudinal direction, and the entire width as the lateral direction. When multiple sensors detect the same object, the current position and speed of the object can be determined by considering the errors in the front-back and left-right directions of the camera 2 and radar 3. Furthermore, the object information required by the alarm braking operation determination unit 203, such as the object's acceleration, is calculated based on the object speed.

[0027] In the vehicle information calculation unit 202, the turning radius of the vehicle 10 required for the vehicle to advance is calculated in the alarm braking operation determination unit 203 based on the vehicle speed obtained from the wheel speed sensor 5 (hereinafter referred to as vehicle speed), the vehicle steering angle obtained from the rudder angle sensor 6 (hereinafter referred to as vehicle steering angle), and the vehicle yaw rate obtained from the yaw rate sensor 7 (hereinafter referred to as vehicle yaw rate).

[0028] In the alarm braking operation determination unit 203, the forward paths of the vehicle 10 and the object are predicted based on the object's current position, speed, and acceleration obtained from the object information integration processing unit 201, and the vehicle's position, speed, acceleration, steering angle, yaw rate, and turning radius obtained from the multiple sensors and the vehicle's own information calculation unit 202. Based on the predicted forward path of the vehicle 10 (hereinafter referred to as the predicted forward path of the vehicle) and the predicted forward path of the object (hereinafter referred to as the predicted forward path of the object), the predicted time of collision between the vehicle 10 and the object (hereinafter referred to as the remaining collision time) is calculated. Based on the remaining collision time, the predicted location of the collision between the vehicle 10 and the object (hereinafter referred to as the predicted collision location) is calculated, and the possibility of a collision between the vehicle 10 and the object is determined (hereinafter referred to as the collision determination). The system calculates a threshold for determining whether braking is required based on the vehicle's speed (hereinafter sometimes referred to as the braking action determination threshold). Based on the comparison between the calculated threshold (braking action determination threshold) and the remaining time of the collision, as well as the result of the collision determination, the system requests and performs braking actions corresponding to the predicted time of collision with the target.

[0029] In the collision alarm calculation unit 204, based on the alarm operation request obtained from the alarm braking operation determination unit 203, it outputs a request to the instrument 8 to display a warning image, or a request to the buzzer 9 to sound a warning sound, or both a request to display a warning image and a request to sound a warning sound.

[0030] In the brake indication value calculation unit 205, based on the braking operation request obtained from the alarm brake operation determination unit 203, the brake command value required to avoid collision with the target is output to the brake control device 12. The brake indication value calculation unit 205 has a first deceleration control unit 206, a second deceleration control unit 207, or both. The first deceleration control unit 206 outputs a first deceleration or a first braking force to the brake control device 12, and the second deceleration control unit 207 outputs a second deceleration or a second braking force to the brake control device 12. The first deceleration or first braking force of the first deceleration control unit 206 and the second deceleration or second braking force of the second deceleration control unit 207 are preset values ​​based on the vehicle, surrounding environment, etc., and the second deceleration or second braking force is set to a value smaller than the first deceleration or first braking force.

[0031] Figure 3 An example of a flowchart of the alarm braking operation determination unit 203, which avoids a collision with a first deceleration or a first braking force in order to shorten the threshold (braking operation determination threshold) calculated in the alarm braking operation determination unit 203 in the collision avoidance assistance of the embodiment of the present invention.

[0032] Figure 3 In step S401, the predicted forward path of the vehicle and the predicted forward path of the object are calculated based on the object position and object velocity obtained from the object information integration and processing unit 201, and the vehicle speed and vehicle yaw rate obtained from the plurality of sensors and the vehicle information calculation unit 202. Alternatively, at least one of the object acceleration and the vehicle acceleration can be considered when calculating the predicted forward path of the vehicle and the predicted forward path of the object.

[0033] In step S402, the remaining collision time is calculated based on the predicted forward path of the vehicle and the predicted forward path of the target. The remaining collision time is the time elapsed until the longitudinal distance from the vehicle 10 to the target (hereinafter referred to as the current longitudinal distance of the target) becomes 0 when the vehicle is traveling at its current speed and the target speed.

[0034] In step S403, the longitudinal and lateral positions of the vehicle at the predicted collision location after the remaining collision time are calculated based on the vehicle's own speed and yaw rate. The longitudinal and lateral positions of the object at the predicted collision location after the remaining collision time are also calculated based on the object's speed and current position.

[0035] In step S404, a collision determination is performed based on the position of the vehicle 10 at the collision prediction location. As an example of the determination method, it is determined whether there is an overlap between the vehicle 10 and the object based on the position of the front end of the vehicle 10 at the collision prediction location and the position of the side of the object at the collision prediction location. If there is an overlap, it is determined that a collision is possible at the collision prediction location, and the collision determination is successful, proceeding to step S405. If the collision determination is unsuccessful, it is determined that the vehicle 10 is unlikely to collide with the object, and steps S405 to S411 (no braking operation) are not performed.

[0036] In step S405, the distance required for the vehicle 10 to stop when it is traveling at its own vehicle speed and decelerated by the first deceleration or first braking force given by the first deceleration control unit 206 (hereinafter referred to as the vehicle stopping distance) is calculated. The time elapsed when the vehicle 10 travels past the vehicle stopping distance at its own vehicle speed is used as a threshold (braking operation determination threshold) for the purpose of determining whether braking is necessary to avoid a collision. In this embodiment, the braking operation determination threshold is set to time for comparison with the collision prediction time, but it can also be set to distance instead of time. If it is set to distance, the vehicle stopping distance is used as the braking operation determination threshold.

[0037] In step S406, it is determined whether the object is traveling on a road intersecting with the vehicle's predicted path based on the vehicle's predicted path and the object's predicted path. If the object is traveling on a road intersecting with the vehicle's predicted path, the determination is made and the process proceeds to step S407; otherwise, the process proceeds to step S411.

[0038] In step S407, the time elapsed from when the object reaches its predicted lateral position, and then passes through the area where the object intersects with the predicted path of the vehicle itself (hereinafter referred to as the predicted intersection area) is calculated (hereinafter referred to as the predicted passage time). The length of the predicted intersection area is calculated based on the width of the vehicle and the total length of the object, but in addition to the width of the vehicle and the total length of the object, the remaining distance can also be considered. The remaining distance takes into account the vehicle speed, the object speed, the positional relationship between the vehicle and the object, and the error of the sensor detection accuracy. The vehicle speed, the object speed, and the positional relationship between the vehicle and the object will cause the overlap ratio between the vehicle and the object at the collision prediction point (hereinafter referred to as the predicted overlap rate) to change, so the predicted overlap rate can be calculated, and the predicted passage time can be calculated based on the calculated predicted overlap rate.

[0039] use Figure 4 When the speed of the vehicle on the intersection road 100 is equal to the speed of the object, the lateral distance from the current position of the vehicle 10 to the current position of the object is relatively long. Figure 4 (Column A) and cases where the horizontal distance is short ( Figure 4The predicted overlap rate between the vehicle 10 and the target at their respective collision prediction locations (column (B)) is explained. 501 represents the current position of the vehicle. 502 and 602 represent the current positions of the target. Compared to the current position 602 of the target, the current position 502 of the target is in a lateral position away from the vehicle 10. 503 represents the position of the vehicle 10 at the collision prediction location calculated in step S403, 504 represents the position of the target at the collision prediction location when the target is currently at position 502, and 604 represents the position of the target at the collision prediction location when the target is currently at position 602. 101 represents the predicted intersection area calculated in step S407. 701 represents the distance from the current position of the target to the collision prediction location. This distance is the same even if the current positions of the targets are different, provided that the target's speed and the remaining collision time are equal. 702 represents the distance required for the target to pass through the predicted intersection area 101 from its position 504 at the collision prediction location. 703 represents the distance required for the object to pass through the predicted intersection area 101 from its position 604 at the collision prediction location. 505 represents the length (ratio) of the portion of the vehicle 10 overlapping with the object at the collision prediction location, i.e., the predicted overlap rate. 605 also represents the predicted overlap rate at the collision prediction location. Compared to the current object position 602, the current object position 502 is in a lateral position away from the vehicle 10. Therefore, with the same object speed, the length of 605 is longer than the length of 505, so the predicted overlap rate at the current object position 502 is smaller than the predicted overlap rate at the current object position 602. Similarly, with the same object speed, the distance of 703 is shorter than the distance of 702, so the predicted passage time of the object at the current object position 602 is shorter than the predicted passage time of the object at the current object position 502.

[0040] Thus, even when the target speed is the same, the predicted passage time will differ due to the predicted overlap rate. Therefore, by calculating the predicted passage time based on the calculated predicted overlap rate, the predicted passage time corresponding to the positional relationship between the vehicle 10 and the target can be calculated. Based on this predicted passage time, the threshold for determining whether braking has occurred (braking operation determination threshold) is changed in step S410. Therefore, excessive braking can be suppressed by applying braking within a shorter distance from the vehicle 10 to the target.

[0041] In step S407, when the target's speed is high or the distance from the vehicle 10 to the target is long, the detection information such as the target's speed and position detected by the sensors contains errors. Therefore, if the predicted passage time calculated based on the information detected by the sensors is shorter than the predicted passage time calculated based on the target's actual position, the time until the target passes the predicted intersection area cannot be guaranteed, and the vehicle 10 may collide with the target. Therefore, when the target's speed is higher than a predetermined speed, or the current longitudinal distance of the target is longer than a predetermined distance, or both the target's speed is higher than a predetermined speed and the current longitudinal distance of the target is longer than a predetermined distance are met, a predetermined time is added to the predicted passage time to prevent the vehicle 10 from colliding with the target.

[0042] The specified speed, specified distance, and specified time (the time added to the predicted passage time) can vary depending on the speed and positional relationship between the vehicle 10 and the object. In other words, the specified speed, specified distance, and specified time (the time added to the predicted passage time) can be calculated based on the speed and positional relationship between the vehicle 10 and the object. To prevent the vehicle 10 from colliding with the object due to its deceleration after braking, the predicted passage time can be calculated by considering the current acceleration of the object, or the possibility of the object decelerating at a certain rate can be considered in advance and the remaining time can be added to the predicted passage time.

[0043] In step S408, the time elapsed until the vehicle 10 reaches the collision prediction location when it is decelerated by the first deceleration or the first braking force given by the first deceleration control unit 206 is calculated based on the vehicle's own speed and current vehicle position (hereinafter referred to as the collision prediction location arrival time or the collision prediction location arrival time during the first deceleration). If the distance between the vehicle 10 and the collision prediction location is longer than the vehicle's stopping distance, the vehicle 10 will stop before reaching the collision prediction location when it is decelerated by the first deceleration or the first braking force given by the first deceleration control unit 206. Therefore, as an example, the collision prediction location arrival time is set to a value greater than the predicted passage time.

[0044] In step S409, it is determined whether the braking operation determination threshold calculated in step S405 needs to be changed (hereinafter referred to as threshold change determination) based on the predicted passage time and the arrival time of the collision prediction location during the first deceleration. If the arrival time of the collision prediction location is longer than the predicted passage time (in other words, the predicted passage time is shorter than the arrival time of the collision prediction location), when the vehicle 10 decelerates with the first deceleration or the first braking force given by the first deceleration control unit 206 and arrives at the collision prediction location, the object has already passed through the predicted intersection area 101. Therefore, it is determined that even if the braking operation determination threshold is shortened, the vehicle 10 will not collide with the object, and the process proceeds to step S410. If the arrival time of the collision prediction location is shorter than the predicted passage time (in other words, the predicted passage time is longer than the arrival time of the collision prediction location), when the vehicle 10 decelerates with the first deceleration or the first braking force given by the first deceleration control unit 206 and arrives at the collision prediction location, the object has not yet passed through the predicted intersection area 101. Therefore, it is determined that the braking operation determination threshold should not be shortened, and the process proceeds to step S411.

[0045] The determination based on the vehicle's own speed and the object's speed can also be incorporated into the threshold change determination. When the vehicle's own speed is slow, the braking action determination threshold is short. If the braking action determination threshold is further shortened, the vehicle 10 will brake closer to the object, potentially increasing the likelihood of a collision. Therefore, the braking action determination threshold is not changed when the vehicle's own speed is slower than a specified value (the specified vehicle speed threshold). When the object's speed is slow, the possibility of the object stopping within the predicted intersection area is considered. Therefore, the braking action determination threshold is not changed when the object's speed is slower than a specified speed (the specified object speed threshold). In other words, changes to the braking action determination threshold are prohibited when the vehicle's own speed or the object's speed is below the specified value, but are permitted when the vehicle's own speed or the object's speed is above the specified value.

[0046] In step S410, the braking operation determination threshold calculated in step S405 is shortened (reduced) by a specified time. The specified time varies depending on the speed and positional relationship between the vehicle 10 and the target.

[0047] Figure 5 As an example, the case where the braking operation determination threshold is not changed in step S410 is shown on the intersection road 100. Figure 5 (Column A) and the case where the braking operation determination threshold is changed in step S410 ( Figure 5Columns (B) and (C) show the positional relationship between the vehicle 10 and the target during braking, as well as the remaining collision time, the lateral position of the target, and the changes in the longitudinal position of the target over time. The vehicle's current position 801 indicates the current position of the vehicle 10, and the target's current position 802 indicates the current position of the target. The predicted position 803 when the vehicle decelerates indicates the position of the vehicle 10 after the collision prediction point arrives at its current position 801 when it decelerates with the first deceleration or first braking force given by the first deceleration control unit 206. The predicted position 804 when the target decelerates indicates the position of the target after the collision prediction point arrives at its current position 802, assuming the target's speed remains constant.

[0048] Braking operation determination threshold 805 represents the braking operation determination threshold calculated in step S405. Braking operation determination threshold 806 and braking operation determination threshold 807 represent the braking operation determination thresholds when the specified time is shortened in step S410. Braking operation determination threshold 806 is set to a value larger than braking operation determination threshold 807.

[0049] Longitudinal distance of the object: 850 ( Figure 5 (A) column indicates the longitudinal distance between the vehicle 10 and the target when the remaining collision time is less than the braking operation judgment threshold 805 and the vehicle 10 starts to decelerate with the first deceleration or the first braking force given by the first deceleration control unit 206.

[0050] Longitudinal distance of the object: 851 Figure 5 (B) indicates the longitudinal distance between the vehicle 10 and the target when the remaining collision time is less than the braking operation judgment threshold 806 and the vehicle 10 begins to decelerate with the first deceleration or the first braking force given by the first deceleration control unit 206.

[0051] Longitudinal distance of the object: 852 Figure 5 The (C) column indicates the longitudinal distance between the vehicle 10 and the target when the remaining collision time is less than the braking operation judgment threshold 807 and the vehicle 10 begins to decelerate with the first deceleration or the first braking force given by the first deceleration control unit 206.

[0052] The deceleration start time 875 indicates the time when the vehicle 10 begins to decelerate with the first deceleration or first braking force given by the first deceleration control unit 206. The object crossing time 876 indicates the time when the object passes through the predicted crossing area 101.

[0053] The arrival time of the vehicle itself 877 indicates the time when the vehicle itself 10 arrives at the collision prediction location after decelerating at the first deceleration or first braking force given by the first deceleration control unit 206 from its current position 801. The arrival time of the collision prediction location 878 indicates the arrival time of the collision prediction location at the current position 801 of the vehicle itself, and the predicted passage time 879 indicates the predicted passage time at the current position 802 of the target.

[0054] The longitudinal distance 851 of the target is shorter than the longitudinal distance 850 of the target, so the braking operation judgment threshold is shortened in step S410, thereby enabling the vehicle 10 to brake at a position closer to the target. The recognition accuracy of the sensor and the prediction accuracy of the forward path of the vehicle 10 and the target are improved, thereby suppressing excessive braking and improving functionality.

[0055] Specifically, an upper limit is set for the prescribed time for shortening the braking operation determination threshold in step S410. For example... Figure 5 As shown in column (C), when braking is activated based on braking activation threshold 807, the arrival time 878 of the collision prediction location is the same as the predicted passage time 879. Therefore, when the vehicle 10 arrives at the collision prediction location, the object passes through the predicted intersection area 101.

[0056] If the braking operation determination threshold is further shortened compared to the braking operation determination threshold 807, the target may not have passed through the predicted intersection area 101 when the vehicle 10 arrives at the collision prediction location, thus a collision may occur. Therefore, a predetermined time for shortening the braking operation determination threshold is set within a range where the predicted passage time 879 is not longer than the collision prediction location arrival time 878.

[0057] Return to Figure 3 In step S411, it is determined whether to apply the brakes based on the remaining collision time calculated in step S402, the braking operation determination threshold calculated in step S405, or the braking operation determination threshold that has been shortened by a predetermined time in step S410. For example, if the threshold change determination (S409) is satisfied, and the remaining collision time is lower than the braking operation determination threshold that has been shortened by a predetermined time in step S410, the braking indication calculation unit 205 requests braking operation under the first deceleration or the first braking force given by the first deceleration control unit 206.

[0058] When the braking operation determination threshold is set to distance, for example, the distance obtained by subtracting the distance traveled by the vehicle 10 at the current speed for a specified time from the vehicle's own stopping distance is used as the braking operation determination threshold. When the current longitudinal distance of the target is lower than the braking operation determination threshold, the braking indication value calculation unit 205 requests the braking operation under the first deceleration or the first braking force given by the first deceleration control unit 206.

[0059] In this embodiment, braking is initiated by shortening the braking determination threshold by a predetermined time within the range where the vehicle 10 can reach the collision prediction location after the object passes through the predicted intersection area 101. However, if the object decelerates after the vehicle 10 initiates braking, the object may not have passed through the predicted intersection area 101 when the vehicle 10 reaches the collision prediction location, thus a collision may occur. Therefore, if the remaining collision time is lower than the braking determination threshold shortened by a predetermined time in step S410, and the vehicle 10 detects the object's deceleration after braking, the braking indication value calculation unit 205 requests a deceleration greater than the first deceleration or a braking force greater than the first braking force (that is, while the vehicle is decelerating with the first deceleration or the first braking force given by the first deceleration control unit 206, the vehicle's deceleration or braking force is increased according to the object's speed (deceleration)). As a result, the vehicle 10 can stop close to the collision prediction location, preventing a collision with the object.

[0060] When both the vehicle 10 and the target are equipped with the collision avoidance assist device 11 of this embodiment, if the remaining collision time is less than the braking operation determination threshold that has been shortened by a predetermined time, and the vehicle 10 and the target begin to decelerate by braking each other, a collision between the vehicle 10 and the target is possible. However, when the deceleration of the other vehicle is detected, the braking indication calculation unit 205 requests a large deceleration or braking force (in this embodiment, a deceleration greater than the first deceleration or a braking force greater than the first braking force) to stop each other close to the collision prediction point, thus preventing a collision between the vehicle 10 and the target.

[0061] Figure 6 An example of a flowchart of the alarm braking operation determination unit 203, which avoids collisions by using a second deceleration or a second braking force to increase the threshold (braking operation determination threshold) calculated in the alarm braking operation determination unit 203 in the collision avoidance assistance of the embodiments of the present invention.

[0062] In steps S901, S902, S903, S904, S905, S906, and S907, the same processing as in steps S401, S402, S403, S404, S405, S406, and S407 is performed respectively.

[0063] In step S908, the time elapsed until the vehicle 10 reaches the collision prediction location when it is decelerated by the second deceleration or second braking force given by the second deceleration control unit 207 is calculated based on the vehicle's own speed and current vehicle position (hereinafter referred to as the collision prediction location arrival time or the collision prediction location arrival time during the second deceleration). When the vehicle is decelerated from its own speed by the second deceleration or second braking force given by the second deceleration control unit 207, if the distance between the vehicle 10 and the collision prediction location is shorter than the distance required for the vehicle 10 to stop (the vehicle's stopping movement distance), the vehicle 10 may not be able to avoid a collision at the collision prediction location. Therefore, as an example, the collision prediction location arrival time during the second deceleration is set to a value larger than the predicted passage time.

[0064] In step S909, similar to step S409, a threshold change determination is performed based on the predicted passage time and the arrival time of the predicted collision location during the second deceleration. If the arrival time of the predicted collision location during the second deceleration is longer than the predicted passage time (in other words, the predicted passage time is shorter than the arrival time of the predicted collision location during the second deceleration), the object has already passed through the predicted intersection area 101 when the vehicle 10 decelerates to the predicted collision location using the second deceleration or second braking force given by the second deceleration control unit 207. Therefore, it is determined that even if the braking determination threshold is extended, the vehicle 10 will not collide with the object, and the process proceeds to step S910. If the arrival time of the predicted collision location during the second deceleration is shorter than the predicted passage time (in other words, the predicted passage time is longer than the arrival time of the predicted collision location during the second deceleration), the object has not yet passed through the predicted intersection area 101 when the vehicle 10 decelerates to the predicted collision location using the second deceleration or second braking force given by the second deceleration control unit 207. Therefore, it is determined that the braking determination threshold will not be extended, and the process proceeds to step S911. Similar to step S409, the determination based on the vehicle's own speed and the target speed can also be added to the threshold change determination.

[0065] In step S910, the braking operation determination threshold calculated in step S905 is extended (increased) by a specified time. The specified time varies depending on the speed and positional relationship between the vehicle 10 and the target.

[0066] Figure 7As an example, this demonstrates the changes in the remaining collision time, the lateral position and longitudinal position of the target, and the deceleration of the vehicle 10 itself over time when the braking operation determination threshold is extended by a predetermined time and deceleration is performed with the second deceleration or the second braking force given by the second deceleration control unit 207, and when deceleration is performed with the first deceleration or the first braking force given by the first deceleration control unit 206 without changing the braking operation determination threshold.

[0067] The dashed graph 1001 represents the remaining collision time when deceleration is performed with the first deceleration or the first braking force given by the first deceleration control unit 206 without changing the braking operation determination threshold. The solid graph 1002 represents the remaining collision time when deceleration is performed with the second deceleration or the second braking force given by the second deceleration control unit 207 after extending the braking operation determination threshold by a predetermined time.

[0068] The dashed graph 1003 represents the longitudinal position of the target when deceleration is performed with the first deceleration or the first braking force given by the first deceleration control unit 206 without changing the braking operation determination threshold. The solid graph 1004 represents the longitudinal position of the target when deceleration is performed with the second deceleration or the second braking force given by the second deceleration control unit 207 after extending the braking operation determination threshold by a predetermined time.

[0069] The deceleration start time 1051 indicates the time when braking is activated when the braking operation judgment threshold is extended by a specified time, while the deceleration start time 1052 indicates the time when braking is activated without changing the braking operation judgment threshold.

[0070] The collision prediction location arrival time 1053 indicates the time when the vehicle 10 arrives at the collision prediction location when deceleration is initiated at deceleration start time 1051 with the second deceleration or the second braking force given by the second deceleration control unit 207. The collision prediction location arrival time 1054 indicates the time when the vehicle 10 arrives at the collision prediction location when deceleration is initiated at deceleration start time 1052 with the first deceleration or the first braking force given by the first deceleration control unit 206.

[0071] By extending the braking action determination threshold by a specified time, compared to not changing the braking action determination threshold, the vehicle 10 can gradually decelerate from a position further longitudinally from the current position of the target, using a second deceleration smaller than the first deceleration or a second braking force smaller than the first braking force to avoid a collision. Therefore, usability can be improved without impairing driver operability.

[0072] Return to Figure 6In step S911, the braking action is determined based on the remaining collision time calculated in step S902, the braking action determination threshold calculated in step S905, or the braking action determination threshold extended by a specified time in step S910.

[0073] If the threshold change determination (S909) is satisfied, for example, if the remaining collision time is lower than the braking operation determination threshold that has been extended by a predetermined time in step S910, the braking indication value calculation unit 205 requests the braking operation under the second deceleration or the second braking force given by the second deceleration control unit 207.

[0074] When the braking operation determination threshold is set to distance, for example, the distance obtained by adding the distance of the vehicle's own vehicle's parking movement to the distance of the vehicle 10 traveling at the current speed for a specified time is used as the braking operation determination threshold. When the current longitudinal distance of the target is lower than the braking operation determination threshold, the braking indication value calculation unit 205 requests the braking operation under the second deceleration or the second braking force given by the second deceleration control unit 207.

[0075] Step S911 is the same as step S411. If the remaining time of collision is lower than the braking operation determination threshold that has been extended by a predetermined time, and the vehicle 10 detects the deceleration of the object after braking, the braking indication value calculation unit 205 requests a deceleration or braking force greater than the second deceleration or the second braking force (that is, when the vehicle is decelerating with the second deceleration or the second braking force given by the second deceleration control unit 207, the deceleration or braking force of the vehicle is increased according to the speed (deceleration) of the object). As a result, the vehicle 10 can stop close to the collision prediction location and prevent a collision with the object.

[0076] Furthermore, when the brake indication value calculation unit 205 has both a first deceleration control unit 206 and a second deceleration control unit 207, it can automatically determine, based on the surrounding environment, whether to shorten the braking operation determination threshold through the above-described processing and perform a collision avoidance action with a first deceleration or a first braking force. Figure 3 Alternatively, extend the braking action threshold and use a second deceleration or second braking force to perform a collision avoidance maneuver. Figure 6 The driver can also decide (choose) in advance.

[0077] As explained above, the collision avoidance assist device 11 of this embodiment calculates the predicted forward path of its own vehicle (predicted forward path of the own vehicle) and the predicted forward path of an object existing on a road intersecting with the own vehicle (predicted forward path of the object). Based on the predicted forward path of the own vehicle (predicted forward path of the own vehicle) and the predicted forward path of the object (predicted forward path of the object), it calculates the remaining time of collision between the own vehicle and the object and the predicted collision location. If the remaining time of collision or the distance traveled by the own vehicle within the remaining time of collision is below the braking operation determination threshold, it applies a predetermined deceleration or braking force (the first deceleration or the first deceleration given by the first deceleration control unit 206). The collision avoidance assist device 11 decelerates the vehicle by applying a second deceleration or a second braking force (given by the second deceleration control unit 207) to avoid a collision with the object. The collision avoidance assist device 11 calculates the predicted time until the vehicle reaches the predicted collision location when the vehicle is decelerated by the predetermined deceleration or braking force. Based on the estimated time required for the object to pass through the intersection area (predicted intersection area) of the predicted path of the object and the predicted path of the vehicle, i.e., the predicted passage time and the predicted collision location arrival time, the braking operation determination threshold is changed (increased or decreased).

[0078] Furthermore, the collision avoidance assist device 11 includes a first deceleration control unit 206 that decelerates its own vehicle with a first deceleration or a first braking force, and a second deceleration control unit 207 that decelerates its own vehicle with a second deceleration or a second braking force that is smaller than the first deceleration or the first braking force. The device calculates the predicted time until its own vehicle reaches the collision prediction location when it is decelerated by the first deceleration control unit 206, i.e., the collision prediction location arrival time during the first deceleration. If the predicted passage time is smaller than the collision prediction location arrival time during the first deceleration, the device reduces the braking operation determination threshold.

[0079] Furthermore, the collision avoidance assist device 11 includes a first deceleration control unit 206 that decelerates its own vehicle with a first deceleration or a first braking force, and a second deceleration control unit 207 that decelerates its own vehicle with a second deceleration or a second braking force that is smaller than the first deceleration or the first braking force. The device calculates the predicted time until its own vehicle reaches the predicted collision location when it is decelerated by the second deceleration control unit 207, i.e., the arrival time of the predicted collision location during the second deceleration. If the predicted passage time is smaller than the arrival time of the predicted collision location during the second deceleration, the device increases the braking operation determination threshold.

[0080] In this embodiment, the collision avoidance assist device 11 compares a threshold for determining whether braking is required (braking operation determination threshold) with the remaining collision time in assisting with collision avoidance of an object traveling in a lane orthogonal to the vehicle (a road intersecting the vehicle). The threshold is shortened (reduced) within a range where the probability of the vehicle colliding with the object is low compared to the remaining collision time. Therefore, compared to conventional collision avoidance assist devices, the vehicle can brake at a point close to the object to avoid a collision. Since braking is performed within a short distance from the vehicle to the object, the accuracy of sensor recognition and the prediction accuracy of the vehicle's and object's paths are improved, and excessive braking is suppressed, thereby improving functionality.

[0081] Furthermore, as a different method than those described above, the braking force or deceleration of the vehicle required to avoid a collision is reduced, and the threshold used to determine whether braking is in operation (the braking operation determination threshold) is extended (increased). By extending the threshold, the vehicle can decelerate more slowly from a position away from the object to avoid a collision compared to before the threshold was extended. Therefore, usability can be improved without compromising driver operability.

[0082] Thus, according to this embodiment, functionality and availability can be improved by suppressing excessive or sudden braking.

[0083] Furthermore, a supplementary explanation will be provided regarding the case where the distance traveled by the vehicle within the remaining time of the collision is used instead of the remaining time of the collision as the comparison object for determining whether braking is required (braking operation determination threshold). The remaining time of the collision is the time until the vehicle collides with the object. In the case of an intersection as described in this embodiment, the remaining time of the collision is the time until the longitudinal positions of the vehicle and the object become equal. Therefore, the distance traveled by the vehicle within the remaining time of the collision is synonymous with the longitudinal distance from the current vehicle position to the object (see reference). Figure 8 (See the left figure). The braking operation determination threshold (also known as the collision remaining time travel distance threshold) is a distance obtained by extending or shortening the distance required for the vehicle to stop when decelerating with deceleration or braking force, according to this embodiment. The braking operation determination threshold (collision remaining time travel distance threshold) is the minimum distance required to avoid a collision. Therefore, the distance traveled by the vehicle in the remaining time of the collision is compared with the braking operation determination threshold (collision remaining time travel distance threshold). If the distance traveled by the vehicle in the remaining time of the collision is greater than the braking operation determination threshold (collision remaining time travel distance threshold) (refer to...). Figure 8(In the central image), even without braking, a collision will not occur, so braking is not activated. However, if the distance the vehicle has traveled in the remaining time before the collision is less than or equal to the braking activation threshold (the remaining time before the collision travels distance threshold) (refer to...) Figure 8 (As shown in the right figure), to activate the brakes to avoid a collision.

[0084] Furthermore, the present invention is not limited to the above-described embodiments, and the following processing can also be added: determining in steps S409 and S909 whether a change in the braking operation determination threshold is needed based on the speed and position information of the vehicle 10 and the object, or the road shape on which the vehicle 10 and the object are traveling. For example, when determining whether a change in the braking operation determination threshold is needed based on the road shape on which the vehicle 10 and the object are traveling, if the vehicle 10 is traveling on a non-priority road, the vehicle 10 must reliably stop near the intersection, so the braking operation determination threshold may not need to be changed.

[0085] In this embodiment, as an example, the case of braking to avoid a collision with a single vehicle that may collide with the vehicle 10 is described. However, if there are multiple objects that may collide with the vehicle 10, after braking to avoid a collision by changing the braking determination threshold to apply the brakes to the object with the highest probability of first collision among the multiple objects, the vehicle 10 may still be struck by another object. Therefore, when there are multiple objects that may collide with the vehicle 10, the vehicle can be reliably stopped in front of the object with the highest probability of first collision among the multiple objects that may collide with the vehicle 10 without changing the braking determination threshold.

[0086] In this embodiment, as an example, a case is described in which the vehicle 10 brakes to avoid a collision without the driver of the vehicle 10 performing vehicle operation. However, when the driver's collision avoidance action can be predicted based on the vehicle operation information of the driver of the vehicle 10 before and after braking, it is sometimes impossible to avoid a collision by relying on the driver's vehicle operation (braking operation). Therefore, the vehicle 10 can be reliably stopped near the collision prediction location without changing the braking operation determination threshold.

[0087] Furthermore, the present invention includes various modifications and is not limited to the embodiments described above. For example, the above embodiments are detailed descriptions provided to illustrate the present invention in an easily understandable manner, and are not necessarily limited to having all the described configurations.

[0088] Furthermore, the aforementioned components, functions, processing units, processing methods, etc., can be partially or entirely implemented in hardware, for example, by designing using integrated circuits, or they can be implemented in software by having a processor interpret and execute programs that implement each function.

[0089] Information such as programs, tables, and files that perform various functions can be stored in storage devices such as memory, hard disks, SSDs (Solid State Drives), or recording media such as IC cards, SD cards, and DVDs.

[0090] Furthermore, the control lines and information lines shown are only those deemed necessary for the explanation and may not represent all the control lines and information lines required for implementation. In fact, almost all components can be considered interconnected. Symbol Explanation

[0091] 2…camera 3…millimeter-wave radar 4…wheels 5…Wheel speed sensor 6…rudder angle sensor 7…Yaw rate sensor 8…instrument 9…buzzer 10… Vehicles (own vehicle) 11…Collision avoidance assist device 12…Brake control device 100… intersection road 101…Predicted cross regions 201…Object Information Integration and Processing Department 202…Automotive vehicle information processing department 203… Alarm Braking Operation Determination Department 204… Collision Alarm Calculation Department 205… Brake Indication Value Calculation Unit 206…First Deceleration Control Unit 207…Second deceleration control unit.

Claims

1. A collision avoidance assist device, which calculates the predicted path of its own vehicle and the predicted path of objects existing on roads intersecting with the own vehicle. The remaining time before collision and the predicted collision location between the vehicle and the object are calculated based on the predicted forward path of the vehicle and the predicted forward path of the object. When the remaining time before the collision occurs, or the distance the vehicle has traveled within the remaining time before the collision occurs, is below the braking operation threshold, the collision avoidance assist device decelerates the vehicle with a predetermined deceleration or braking force to avoid a collision with the object. The calculation determines the predicted time until the vehicle reaches the predicted collision location when it decelerates at the specified deceleration or braking force; this is the collision prediction location arrival time. The braking action determination threshold is adjusted based on the estimated time required for the object to pass through the intersection area of ​​the object's predicted path of travel and the vehicle's predicted path of travel, i.e., the predicted passage time and the arrival time of the predicted collision location.

2. The collision avoidance assist device according to claim 1, characterized in that, The collision avoidance assist device includes a first deceleration control unit that decelerates the vehicle with a first deceleration or a first braking force, and a second deceleration control unit that decelerates the vehicle with a second deceleration or a second braking force that is smaller than the first deceleration or the first braking force. The calculation calculates the predicted time from when the vehicle reaches the predicted collision location while it is decelerating with the help of the first deceleration control unit, which is the time to reach the predicted collision location during the first deceleration. If the predicted passage time is less than the arrival time of the predicted collision location during the first deceleration, the braking operation determination threshold is reduced.

3. The collision avoidance assist device according to claim 1, characterized in that, The collision avoidance assist device includes a first deceleration control unit that decelerates the vehicle with a first deceleration or a first braking force, and a second deceleration control unit that decelerates the vehicle with a second deceleration or a second braking force that is smaller than the first deceleration or the first braking force. The calculation calculates the predicted time from when the vehicle reaches the predicted collision location while decelerating with the help of the second deceleration control unit, which is the time to reach the predicted collision location during the second deceleration. If the predicted passage time is less than the arrival time of the predicted collision location during the second deceleration, the braking operation determination threshold is increased.

4. The collision avoidance assist device according to claim 1, characterized in that, When the vehicle's own speed is greater than a predetermined vehicle speed threshold, the collision avoidance assist device allows for a change in the braking operation determination threshold.

5. The collision avoidance assist device according to claim 1, characterized in that, If the speed of the object is greater than a predetermined object speed threshold, the collision avoidance assist device allows for a change in the braking operation determination threshold.

6. The collision avoidance assist device according to claim 1, characterized in that, The collision avoidance assist device calculates the overlap ratio (i.e., the predicted overlap rate) between the vehicle and the object at the predicted collision location based on the predicted path of the vehicle and the predicted path of the object, and calculates the predicted passage time based on the predicted overlap rate.

7. The collision avoidance assist device according to claim 1, characterized in that, The collision avoidance assist device calculates the time added to the predicted passage time based on at least one of the object's speed or the distance between the object and the vehicle itself.

8. The collision avoidance assist device according to claim 1, characterized in that, When the vehicle is decelerating, the collision avoidance assist increases the deceleration or braking force of the vehicle based on the speed of the object.

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