Driving assistance systems

Abstract

To provide a driving support device which can make it easy to perform collision avoidance by automatic brake to prevent a vehicle from colliding an object even when an obstacle exists at an outer peripheral part of a detection range.SOLUTION: A driving support device comprises: an object detection device which detects an object in front of a vehicle; an automatic brake device; and a driving support ECU constituted to perform collision avoidance control for automatically braking the vehicle by the automatic brake device when it is determined that the vehicle is likely to collide with the object detected by the object detection device, wherein the driving support ECU automatically brakes the vehicle at low deceleration, when it is determined that the object which is likely to collide with the vehicle is located in a predetermined area set at an outer edge of a detection range of the object detection device when viewed from the above, in comparison with the case when it is determined that the object which is likely to collide with the vehicle is located outside the predetermined area in the detection range.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a driving support device for vehicles such as automobiles.

Background Art

[0002] As one of the driving support devices for vehicles such as automobiles, there is known a driving support device including a detection device having a camera sensor and a radar sensor, and configured to avoid a collision by automatic braking when there is a risk of colliding with an obstacle detected in front of the vehicle by the detection device. For example, this type of driving support device is described in Patent Document 1 below.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

[0004] 〔Problems to be Solved by the Invention〕 In the driving support device as described above, the reliability of the detected obstacle is determined so that collision avoidance by automatic braking is not unnecessarily performed, and collision avoidance by automatic braking is performed when the reliability of the obstacle is equal to or higher than a reference value.

[0005] When an obstacle is at the outer peripheral portion of the detection range by the detection device, a part of the obstacle moves outside the detection range as the vehicle travels, and due to the reliability of the obstacle not becoming equal to or higher than the reference value, collision avoidance by necessary automatic braking may not be performed.

[0006] The present invention provides an improved driving support device that can facilitate collision avoidance by automatic braking to prevent the vehicle from colliding with an object even when the object such as an obstacle is at the outer peripheral portion of the detection range by the detection device.

[0007] 〔Means for Solving the Problems and Effects of the Invention〕 According to the present invention, a driver assistance device (100) is provided, which includes an object detection device (16) for detecting an object in front of a vehicle (102), an automatic braking device (34) for automatically braking the vehicle, and a control unit (driver assistance ECU 10) configured to perform collision avoidance control, which automatically brakes the vehicle using the automatic braking device (S110) when it is determined that there is a risk of the vehicle colliding with an object (P) detected by the object detection device and that the reliability of the object is equal to or greater than a first reference value (S40, S90).

[0008] The object detection device (16) includes two object detection sensors (camera sensor 12 and radar sensor 14) with different detection ranges. The control unit (driving support ECU 10) detects when an object (P) that is likely to collide with the vehicle (102) is viewed from above. Objects are detected only by the object detection sensor with the wider detection range. A predetermined area set at the outer edge of the detection range (B) When it is determined that an object is located in (S62), the object that is likely to collide with the vehicle The overlapping of two object detection sensors Within the detection range be The system is configured to automatically brake the vehicle at a lower deceleration rate compared to when it was determined that the vehicle was under stress (S140).

[0009] Furthermore, according to the present invention, the present invention includes the step (S10) of detecting an object (P) in front of a vehicle (102) using an object detection device (16), and when it is determined that there is a risk of the vehicle colliding with the object detected by the object detection device and that the reliability of the object is equal to or greater than a first reference value (S40, S90), collision avoidance control that automatically brakes the vehicle. Control unit (driving support ECU10) A driving assistance method is provided that includes the steps to be performed (S110).

[0010] The object detection device (16) includes two object detection sensors (camera sensor 12, radar sensor 14) with different detection ranges. Collision avoidance control This refers to an object (P) that is likely to collide with the vehicle (102), when viewed from above. Objects are detected only by the object detection sensor with the wider detection range. When it is determined that an object is located in a predetermined area set at the outer edge of the detection range (S62), the object that is likely to collide with the vehicle The overlapping of two object detection sensors The system includes a step (S140) in which the vehicle is automatically braked at a lower deceleration rate than when it is determined to be located outside a predetermined area within the detection range.

[0013] The above-mentioned driving support device and Driving assistance methods In the law According to the report, an object that is likely to collide with a vehicle, when viewed from above Objects are detected only by the object detection sensor with the wider detection range. When it is determined that an object is located in a predetermined area set at the outer edge of the detection range, it is determined that the object is likely to collide with the vehicle. The overlapping of two object detection sensors The vehicle is automatically braked at a lower deceleration rate than when it is determined to be outside a predetermined area within the detection range.

[0014] An object that poses a risk of collision with a vehicle approaches the vehicle as it moves. When the vehicle automatically brakes at a low deceleration, the relative speed of the vehicle to the object decreases compared to when the vehicle does not automatically brake at a low deceleration. Therefore, the object is more likely to move from a predetermined area to outside the predetermined area within the detection range. As a result, the reliability of the object increases and it is more likely to exceed the first reference value, making it easier to perform collision avoidance control, and the risk of the vehicle colliding with the object can be reduced by collision avoidance control.

[0016] Also, When an object is within the detection range for a single object, the object is detected as two objects. sensor The reliability of the object is lower compared to when it is within the overlap detection range detected by the above method. Driving assistance device and driving assistance method According to this, the predetermined area is set at the outer edge of the individual detection range, so the predetermined area can be set at the outer edge of the detection range where the reliability of the object is low.

[0017] Also, This invention Driving assistance systems In this case, the control unit (driving support ECU10) is, There is a risk of collision with vehicle (102). object (P) but , set at the outer edge of the detection range of the object detection device (16) when viewed from above. designated area (B) Furthermore, when it is determined that the reliability of the object is greater than or equal to a second criterion value which is less than the first criterion value. (S62, S120) Compared to when it is determined that an object that may collide with the vehicle is located outside a predetermined area within the detection range, It is configured to automatically brake the vehicle at a low deceleration (S140). Furthermore, in the driving assistance method of the present invention, the collision avoidance control includes a step (S140) in which, when an object (P) that is likely to collide with the vehicle (102) is located in a predetermined area (B) set at the outer edge of the detection range of the object detection device when viewed from above, and the reliability of the object is determined to be greater than or equal to a second reference value which is smaller than a first reference value (S62, S120), the vehicle is automatically braked at a lower deceleration rate than when it is determined that the object that is likely to collide with the vehicle is located outside the predetermined area within the detection range.

[0018] According to the latter driving assistance device and driving assistance method described above, when an object that may collide with the vehicle is located in a predetermined area set at the outer edge of the detection range of the object detection device when viewed from above, and the reliability of the object is determined to be greater than or equal to a second standard value which is less than the first standard value, the vehicle is automatically braked at a lower deceleration rate than when it is determined that the object that may collide with the vehicle is located outside the predetermined area within the detection range. Therefore, similar to the former driving assistance device and driving assistance method described above, the relative speed of the vehicle with respect to the object decreases, making it easier for the object to move from a predetermined area to outside the predetermined area within the detection range. As a result, the reliability of the object increases and it is more likely to exceed the first reference value, making it easier to perform collision avoidance control, and the risk of the vehicle colliding with the object can be reduced by collision avoidance control. Also, the aboveThe latter refers to a driver assistance device and driver assistance method. According to this, even if an object is in a predetermined area, when it is determined that the reliability of the object is less than a second reference value, the vehicle is not automatically braked at a low deceleration. Therefore, in a situation where the reliability of the object is low, it is possible to avoid the vehicle being unnecessarily braked.

[0019] Other objects, other features, and attendant advantages of the present invention will be readily understood from the description of embodiments of the present invention described while referring to the following drawings.

Brief Description of the Drawings

[0020] [Figure 1] It is a schematic configuration diagram showing a driving support device according to an embodiment. [Figure 2] It is a flowchart showing a driving support control routine of an embodiment. [Figure 3] It is a flowchart showing a subroutine for calculating the reliability D executed in step S60 of FIG. 2. [Figure 4] It is a diagram (A) showing rectangular coordinates, a diagram (B) showing the movement of a vehicle and an object, and a diagram (C) showing the relationship between the x coordinate X' of the relative position of the object with respect to the vehicle and the time to collision TTC. [Figure 5] It is a diagram showing examples of the operation of a conventional driving support device and an embodiment in a situation (A) where the vehicle is traveling straight and a pedestrian crosses in front of the vehicle and a situation (B) where the vehicle is turning right and a pedestrian crosses in front of the vehicle. [Figure 6] It is a diagram showing examples of the trajectory of a stationary object in a situation (A) where the vehicle is traveling straight and approaching a stationary object located on the roadside on the right front and a situation (B) where the vehicle is turning right and approaching a stationary object located on the roadside on the right front.

Mode for Carrying Out the Invention

[0021] Hereinafter, a driving support device according to an embodiment of the present invention will be described in detail while referring to the attached drawings.

[0022] As shown in Figure 1, the driver assistance device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driver assistance ECU 10. The vehicle 102 may be a vehicle capable of autonomous driving and is equipped with a drive ECU 20, a brake ECU 30, and a meter ECU 40. ECU means an electronic control unit that mainly consists of a microcomputer. In the following description, electric power steering will be referred to as EPS.

[0023] Each ECU's microcomputer includes a CPU, ROM, RAM, read / write non-volatile memory (N / M), and an interface (I / F). The CPU implements various functions by executing instructions (programs, routines) stored in ROM. Furthermore, these ECUs are interconnected via CAN (Controller Area Network) 104, enabling data exchange (communication). Therefore, detection values ​​from sensors (including switches) connected to a specific ECU are transmitted to other ECUs.

[0024] The driver assistance ECU 10 is a central control unit that performs driver assistance controls such as collision avoidance control, follow-vehicle distance control, and lane departure prevention control. In this embodiment, the driver assistance ECU 10 works in cooperation with other ECUs to perform collision avoidance control by automatic braking, as will be described in detail later.

[0025] The driver assistance ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a switch 18. The camera sensor 12 and the radar sensor 14 each include multiple camera devices and multiple radar devices, respectively. The camera sensor 12 and the radar sensor 14 function as an object detection device 16 that detects objects at least in front of the vehicle 102.

[0026] Each camera device of the camera sensor 12, although not shown in the figure, includes a camera unit that photographs the area around the vehicle 102 and a recognition unit that analyzes the image data obtained from the camera unit to recognize objects such as other vehicles and pedestrians. The recognition unit supplies information about the recognized objects to the driver assistance ECU 10 at predetermined intervals.

[0027] Each radar device of the radar sensor 14 is equipped with a radar transceiver and a signal processing unit (not shown). The radar transceiver emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (e.g., other vehicles, bicycles, guardrails, etc.) within the emission range. The signal processing unit supplies information representing the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object to the vehicle at predetermined intervals, based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves. LiDAR (Light Detection And Ranging) may be used instead of the radar sensor 14, or in addition to the radar sensor 14.

[0028] Switch 18 is located in a position that can be operated by the driver, such as on a steering wheel (not shown in Figure 1), and can be switched on and off by the driver. When switch 18 is on, a signal indicating this is supplied to the driver assistance ECU 10, and collision avoidance control is executed.

[0029] The drive ECU 20 is connected to a drive unit 22, which accelerates the vehicle 102 by applying driving force to the drive wheels, which are not shown in Figure 1. Under normal circumstances, the drive ECU 20 controls the drive unit 22 so that the driving force generated by the drive unit 22 changes in accordance with the driver's driving operation, and when it receives a command signal from the driver assistance ECU 10, it controls the drive unit 22 based on the command signal.

[0030] Furthermore, the drive unit 22 is not limited to a combination of an internal combustion engine and an automatic transmission. That is, the drive unit 22 may be any drive unit known in the art, such as a combination of an internal combustion engine and a continuously variable transmission, a so-called hybrid system consisting of an internal combustion engine and a motor, a so-called plug-in hybrid system, a combination of a fuel cell and a motor, or a motor.

[0031] The braking ECU 30 is connected to a braking device 32, which decelerates the vehicle 102 by applying braking force to the wheels (not shown in Figure 1). Under normal circumstances, the braking ECU 30 controls the braking device 32 so that the braking force generated by the braking device 32 changes in accordance with the driver's braking operation. When it receives a command signal from the driver assistance ECU 10, it performs automatic braking by controlling the braking device 32 based on the command signal. Therefore, the braking ECU 30 and the braking device 32 function as an automatic braking system 34.

[0032] A warning device 42 is connected to the meter ECU 40. The warning device 42 is activated when it is determined that there is a risk of the vehicle 102 colliding with an obstacle, and issues a warning, that is, a warning that there is a risk of the vehicle 102 colliding with an obstacle. The warning device 52 may be any of the following: a visual warning device such as a display or warning lamp, an auditory warning device such as a warning buzzer, or a tactile warning device such as seat vibration, or any combination thereof.

[0033] The driving operation sensor 50 and the vehicle condition sensor 60 are connected to CAN 104. Information detected by the driving operation sensor 50 and the vehicle condition sensor 60 (referred to as sensor information) is transmitted to CAN 104. The sensor information transmitted to CAN 104 can be used as appropriate by each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to CAN 104 from that specific ECU.

[0034] The driving operation sensor 50 includes a drive operation amount sensor for detecting the amount of operation of the accelerator pedal, a braking operation amount sensor for detecting master cylinder pressure or the force applied to the brake pedal, and a brake switch for detecting whether or not the brake pedal is operated. Furthermore, the driving operation sensor 60 includes a steering angle sensor for detecting the steering angle θ, a steering torque sensor for detecting the steering torque Ts, and the like.

[0035] The vehicle state sensor 60 includes a vehicle speed sensor for detecting the vehicle speed V of the vehicle 102, a longitudinal acceleration sensor for detecting the longitudinal acceleration of the vehicle, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, a roll angle acceleration sensor for detecting the roll angle acceleration of the vehicle, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0036] In this embodiment, the ROM of the driver assistance ECU 10 stores a collision avoidance control program. This control program corresponds to the flowchart shown in Figures 2 and 3, and collision avoidance control is executed according to this flowchart.

[0037] <Collision Avoidance Control Program> Next, the collision avoidance control in the embodiment will be described with reference to the flowcharts shown in Figures 2 and 3. The collision avoidance control according to the flowcharts shown in Figures 2 and 3 is repeatedly executed at predetermined intervals by the CPU of the driver assistance ECU 10 when switch 18 is ON, and terminates when switch 18 is OFF. In the following description, collision avoidance control will be referred to as "this control".

[0038] First, in step S10, the CPU determines whether or not an object has been detected in front of the vehicle 102 by the object detection device 16. If the CPU determines that an object has been detected, it proceeds to step S30; if it determines that an object has been detected, it proceeds to step S20. At the start of this control, prior to step S10, the flag Fb, described later, is initialized to 0.

[0039] In step S20, the CPU sets up a Cartesian coordinate system as shown in Figure 4(A), with the origin located at the center of the front end of the vehicle 102, and the lateral direction and direction of travel being the x-axis and y-axis, respectively. In Figure 4(A), the vehicle speed is Vv, the yaw rate of the vehicle 102 is ω with right turning direction as positive, and the turning radius of the vehicle is R. The coordinates of the current position of object P are (X0, Y0), the ground velocity of object P is Vp, and the angle between the direction of movement of object P and the direction of travel of the vehicle 102 is θ.

[0040] In step S30, the CPU erases the Cartesian coordinates if they have been set.

[0041] In step S40, the CPU determines whether or not there is a possibility that vehicle 102 will collide with the object detected in step S10. If the CPU determines that there is a possibility, in step S50 it sets the confidence level D of the object to 0%. If the CPU determines that there is a possibility, in step S60 it calculates the confidence level D of the object according to the flowchart shown in Figure 3.

[0042] The turning radius R of the vehicle can be calculated according to equation (1) below, and the x-coordinate Xv and y-coordinate Yv of the position of the vehicle 102 after time t are expressed by equations (2) and (3) below, respectively. R = Vp / ω …(1) Xv = R - Rcosωt …(2) Yv = Rsinωt …(3)

[0043] The x-coordinate Xp and y-coordinate Yp of the position of object P after time t are expressed by equations (4) and (5) below, respectively. Xp = Vptsinθ + X0 …(4) Yp = Vptcosθ + Y0 …(5)

[0044] The difference in x-coordinates X and y-coordinates Y between vehicle 102 and object P are expressed by the following equations (6) and (7). X = Xp - Xv …(6) Y = Yp - Yv …(7)

[0045] Assuming that the vehicle 102 continues to travel and the object P continues to move, and assuming that the coordinates are located at the front end of the vehicle 102 after time t, the x-coordinate X' and y-coordinate Y' of the relative position of the object to the vehicle are expressed by the following equation (8).

number

[0046] Expanding equation (8), the coordinates X' and Y' are expressed by equations (9) and (10) below, respectively.

number

[0047] Assume that vehicle 102 and object P are in the positions shown in Figure 4(B) at times ta and tb. At time tb, coordinate Y' becomes 0. Therefore, if we find the time t when Y' becomes 0, that is, the time t when the left side of equation (10) becomes 0, and substitute that time t into equation (9), and the absolute value of coordinate X' obtained is less than or equal to half the width W of vehicle 102, then it can be determined that there is a possibility of the vehicle colliding with the object.

[0048] Figure 4(C) shows the relationship between the x-coordinate X′ of the object's relative position to the vehicle and the time to collision (TTC). Vr is the relative velocity of vehicle 102 approaching object P, and Dr is the distance between vehicle 102 and object P. The time to collision (TTC) is calculated by dividing the distance Dr by the relative velocity Vr.

[0049] As shown by the dashed arrow in Figure 4(C), even if object P is within the width of vehicle 102 when TTC is large, if the absolute value of coordinate X' exceeds half the width W of vehicle 102 when TTC is 0, the vehicle will not collide with object P.

[0050] In contrast, as shown by the solid arrow, even if object P is outside the width range of vehicle 102 when TTC is large, if the absolute value of coordinate X' is less than or equal to half the width W of vehicle 102 when TTC is 0, the vehicle will collide with object P.

[0051] In step S90, the CPU determines whether the confidence level D of the object is 100%. If the CPU determines it is not 100%, it proceeds to step S120; if it determines it is 100%, it proceeds to step S100.

[0052] In step S100, the CPU estimates the relative velocity Vr of the vehicle 102 as it approaches object P and the distance Dr between the vehicle 102 and object P, and calculates the time until collision TTC by dividing the distance Dr by the relative velocity Vr. Furthermore, the CPU determines whether the time until collision TTC is less than or equal to a first reference value TTC1 (a positive constant). If the CPU determines it is not true, it terminates this control; if it determines it is true, it proceeds to step S110.

[0053] In step S110, the CPU calculates a high target deceleration to prevent the vehicle 102 from colliding with object P, in a manner known in the art. Furthermore, the CPU outputs a signal indicating a high target deceleration to the braking ECU 30, thereby automatically braking the vehicle at a high deceleration.

[0054] In step S120, the CPU determines whether the confidence level D of the object is 50% or not. If the CPU determines it is not 50%, it terminates this control; if it determines it is 50%, it proceeds to step S130.

[0055] In step S130, the CPU calculates the time until collision (TTC) in the same manner as in step S100, and determines whether the time until collision (TTC) is less than or equal to the second reference value TTC2 (a positive constant greater than the first reference value TTC). If the CPU determines it is not a collision, it terminates this control; if it determines it is a collision, it proceeds to step S140.

[0056] In step S140, the CPU outputs a signal to the braking ECU 30 indicating a target deceleration lower than the above-mentioned high target deceleration, thereby automatically braking the vehicle at a lower deceleration than in step S110.

[0057] In step S62 of the confidence level D calculation routine shown in Figure 3, the CPU determines whether or not object P is in area B within the object detection area of ​​the object detection device 16. Note that if at least a part of the object is in area B, it may be determined that the object is in area B. If the CPU makes a positive determination, it proceeds to step S74; if it makes a negative determination, in step S64, it sets the confidence level D of the object to 50%. Furthermore, if flag Fb is 1, the CPU resets flag Fb to 0.

[0058] In this embodiment, the object detection area by the camera sensor 12 is narrower than the object detection area by the radar sensor 14. As shown in Figures 5 and 6, area A is the area where an object is detected by at least one of the camera sensor 12 and the radar sensor 14. In contrast, area B is a predetermined area set in a band shape at the outer edge of the object detection area by the radar sensor 14 alone. The width of the predetermined area, i.e., the width of area B, may be about 50 cm to 1 m, and may be set to be larger the further it is from the vehicle 102. When an object is in area B, depending on the relative displacement between the vehicle 102 and the object, at least a part of the object may fall outside the object detection area of ​​the radar sensor 14, making it difficult to detect the object.

[0059] In step S66, the CPU estimates the type of object and sets the coefficients Ka and Kb (positive constants) in equation (11) below according to the type of object. Furthermore, the CPU calculates the likelihood L of the object according to equation (11) below, based on the object's ground velocity Vp and the radar cross-sectional area (hereinafter referred to as the RCS value) of the radar sensor 14. L = KaVp + KbRCS value …(11)

[0060] In step S68, the CPU determines a reference value Lc for determining the likelihood L of an object by referring to Table 1 below based on the type of object. Furthermore, the CPU determines whether the likelihood L of the object calculated in step S66 is greater than or equal to the reference value Lc. If the CPU makes a negative determination, it proceeds to step S90; if it makes a positive determination, it adds 25% to the confidence level D of the object in step S70. [Table 1]

[0061] In step S72, the CPU determines whether the number of times N in which it determined that object P was detected in step S10 is equal to or greater than the first reference value N1 (a positive integer). If the CPU determines that it is not, it proceeds to step S90; if it determines that it is, it proceeds to step S86.

[0062] In step S74, the CPU determines whether the flag Fb is 1, that is, whether the confidence level D of the object has already been set to 50%. If the CPU makes a positive determination, it proceeds to step S90; if it makes a negative determination, it proceeds to step S76.

[0063] In step S76, the CPU determines whether the ground velocity Vp of object P is 2 km / h or greater, that is, whether object P is a moving object or a stationary object. If the CPU makes a positive determination, in step S78, it sets the object's confidence level D to 25%. If the CPU makes a negative determination, in step S80, it sets the object's confidence level D to 0%.

[0064] In step S82, the CPU determines whether the number of times N was determined to have detected object P in step S10 is equal to or greater than the second reference value N2 (a positive integer smaller than the first reference value N1). If the CPU determines it is not true, it proceeds to step S90; if it determines it is true, it proceeds to step S84.

[0065] In step S84, the CPU sets the flag Fb to 1, and in step S82, the CPU adds 25% to the confidence level D of the object.

[0066] <Operation of the embodiment> Next, the operation of the embodiment will be described for the cases where object P is a pedestrian (C1) and where object P is a stationary object (C2). (C1) When object P is a pedestrian (C1-1) When a pedestrian crosses in front of vehicle 102 (Figure 5(A))

[0067] The left half of Figure 5(A) shows a situation where vehicle 102 is traveling straight and pedestrian 110 is crossing in front of vehicle 102, while the right half of Figure 5(A) shows an example of the operation of a conventional driver assistance system and embodiment in the situation shown in the left half. As mentioned above, region A is the region where an object is detected by at least one of the camera sensor 12 and the radar sensor 14. In contrast, region B is a predetermined region set in the shape of a band at the outer edge of the object detection region by the radar sensor 14 alone. These points are also true in Figures 5(B), 6(A), and 6(B) described later.

[0068] In conventional driver assistance systems, as the vehicle 102 and pedestrian 110 move, the pedestrian is displaced relative to areas A and B, for example, as shown by a dashed trajectory. Since the pedestrian is mainly displaced in area B, even if detected, the reliability of the object is not high. Therefore, the vehicle 102 may not be decelerated at a high deceleration rate by automatic braking.

[0069] In contrast, according to the embodiment, a positive determination is made in steps S62 and S76 of the confidence level D calculation routine shown in Figure 3, and the confidence level D of the object is set to 25% in step S78. When the number of times N that a pedestrian has been detected in step S10 becomes equal to or greater than the second reference value N2, a positive determination is made in step S82, and 25% is added to the confidence level D of the object in step S86, resulting in a confidence level D of 50%.

[0070] Therefore, affirmative decisions are made in steps S10 and S40 of the flowchart shown in Figure 2, and negative and affirmative decisions are made in steps S90 and S120, respectively. Furthermore, when vehicle 102 approaches a pedestrian and the time to collision (TTC) becomes less than or equal to the second reference value TTC2, an affirmative decision is made in step S130, and the vehicle is automatically braked at a lower deceleration than in step S110 (S140).

[0071] When a vehicle is braked with a low deceleration, the speed at which the vehicle approaches the pedestrian decreases. In the right half of Figure 5(A), if braking with a low deceleration begins at point Q1, the pedestrian's trajectory will have a smaller inclination angle than the dashed trajectory, as shown by the solid line. As a result, the pedestrian's trajectory will pass through region A, and a negative determination is made in step S62.

[0072] When the likelihood L becomes equal to or greater than the reference value Lc (S68), and the number of times N is determined to have detected object P becomes equal to or greater than the first reference value N1 (S72), the confidence level D of the object becomes 100% (S86). Therefore, a positive determination is made in steps S10, S40, and S90. When the time to collision TTC becomes less than or equal to the first reference value TTC (S100), the vehicle is automatically braked with a high deceleration (S110).

[0073] If automatic braking with high deceleration is initiated at point Q2, the inclination angle of the pedestrian's trajectory, shown by the solid line, becomes even smaller than the inclination angle of the pedestrian's trajectory from point Q1 to point Q2. As a result, the solid line trajectory will not reach the vehicle, thus preventing the vehicle from colliding with the pedestrian.

[0074] (C1-2) When vehicle 102 turns right and a pedestrian crosses in front of the vehicle (Figure 5(B)) The left half of Figure 5(B) shows a situation where vehicle 102 is turning right and pedestrian 110 is crossing in front of vehicle 102 after the turn, while the right half of Figure 5(B) shows an example of the operation of a conventional driver assistance system and embodiment in the situation shown in the left half.

[0075] Similar to the case in Figure 5(A), in the case of conventional driver assistance systems, pedestrians primarily displace within area B, as shown by the dashed trajectory, for example, so even if they are detected, the reliability of the object is not high. Therefore, the vehicle 102 may not be decelerated at a high deceleration rate by automatic braking.

[0076] In contrast, according to this embodiment, as in the case of Figure 5(A), braking with a low deceleration is initiated at point Q1, and the pedestrian's trajectory, shown by the solid line, passes through area A. Furthermore, automatic braking with a high deceleration is initiated at point Q2, and the pedestrian's trajectory no longer reaches the vehicle, thus preventing the vehicle from colliding with the pedestrian.

[0077] (C2) When object Pt is stationary (C2-1) When vehicle 102 approaches a stationary object to the right front (Figure 6(A)) The left half of Figure 6(A) shows a situation in which vehicle 102 is traveling straight and approaching a stationary object P located on the roadside to the right front, while the right half of Figure 6(A) shows an example of the trajectory of stationary object P in the situation shown in the left half.

[0078] As shown in the right half of Figure 6(A), as the vehicle moves, the stationary object P traces a trajectory that moves away from the vehicle and in the opposite direction. Therefore, even if an affirmative judgment is made in step S10, a negative judgment is made in step S40, so the vehicle does not brake due to automatic braking, but the vehicle does not collide with the stationary object.

[0079] (C2-2) When vehicle 102 turns right and approaches a stationary object to the right front (Figure 6(B)) As shown in the right half of Figure 6(B), in the case of conventional driver assistance systems, for example, as shown by the dashed trajectory, stationary objects are displaced in region B as they pass through the detection area, so even if they are detected, the reliability of the object is not high. Therefore, although vehicle 102 is not decelerated at a high deceleration rate by automatic braking, it does not collide with stationary objects.

[0080] Furthermore, according to this embodiment, even if an affirmative determination is made in step S62, a negative determination is made in step S76, so the confidence level D of the object becomes 0% (S80). Therefore, since negative determinations are made in steps S90 and S120, the vehicle does not brake due to automatic braking, but the vehicle does not collide with the stationary object.

[0081] Although the present invention has been described in detail above with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, and that various other embodiments are possible within the scope of the present invention.

[0082] For example, in the embodiment described above, the object detection area by the camera sensor 12 is narrower than the object detection area by the radar sensor 14. However, the object detection area by the radar sensor 14 may be narrower than the object detection area by the camera sensor 12. In that case, area B is a predetermined area set in a band shape at the outer edge of the object detection area by the camera sensor 12 alone.

[0083] Furthermore, in the above case, the likelihood L of the object is calculated according to equation (12) below, based on the object's ground velocity Vp and edge-focused features (HOG features). Note that the coefficients Kc and Kd are also set according to the type of object. L = KcVp + KdHOG features …(12)

[0084] Furthermore, in the above-described embodiment, the object detection device 16 is a combination of a camera sensor 12 and a radar sensor 14. However, the object detection device may be a combination of two camera sensors or two radar sensors, or a combination of a camera sensor or radar sensor and a laser sensor. [Explanation of Symbols]

[0085] 10…Driver assistance ECU, 12…Camera sensor, 14…Radar sensor, 16…Object detection device, 18…Switch, 20…Drive ECU, 22…Drive system, 30…Brake ECU, 32…Brake system, 34…Automatic braking system, 40…Meter ECU, 42…Warning device, 50…Driver operation sensor, 60…Vehicle status sensor, 100…Driver assistance device, 102…Vehicle

Claims

1. A driver assistance system comprising: an object detection device for detecting an object in front of a vehicle; an automatic braking device for automatically braking the vehicle; and a control unit configured to perform collision avoidance control by automatically braking the vehicle using the automatic braking device when it is determined that there is a risk of the vehicle colliding with an object detected by the object detection device and that the reliability of the object is equal to or greater than a first standard value, The object detection device includes two object detection sensors with different detection ranges. The control unit is configured to automatically brake the vehicle at a lower deceleration rate than when it is determined that an object likely to collide with the vehicle is located in a predetermined area set at the outer edge of the single detection range where the object is detected only by the object detection sensor with the wider detection range when viewed from above, compared to when it is determined that the object likely to collide with the vehicle is located in the overlapping detection ranges of the two object detection sensors.

2. A driving assistance device comprising: an object detection device for detecting an object in front of a vehicle; an automatic braking device for automatically braking the vehicle; and a control unit configured to perform collision avoidance control by automatically braking the vehicle using the automatic braking device when it is determined that there is a risk of the vehicle colliding with an object detected by the object detection device and the reliability of the object is equal to or greater than a first reference value, The control unit is configured to automatically brake the vehicle at a lower deceleration rate than when it is determined that an object likely to collide with the vehicle is located outside the predetermined area within the detection range of the object detection device when viewed from above, and that the reliability of the object is greater than or equal to a second reference value which is less than the first reference value.

3. A driving assistance method comprising the steps of: detecting an object in front of a vehicle using an object detection device; and, when it is determined that there is a risk of the vehicle colliding with the object detected by the object detection device and that the reliability of the object is equal to or greater than a first reference value, performing collision avoidance control by a control unit to automatically brake the vehicle, The object detection device includes two object detection sensors with different detection ranges. The collision avoidance control is a driving assistance method characterized by including a step in which, when it is determined that an object that may collide with the vehicle is located in a predetermined area set at the outer edge of the single detection range where the object is detected only by the object detection sensor with the wider detection range when viewed from above, the vehicle is automatically braked at a lower deceleration rate than when it is determined that the object that may collide with the vehicle is located in the overlapping detection ranges of the two object detection sensors.

4. A driving assistance method comprising the steps of: detecting an object in front of a vehicle using an object detection device; and, when it is determined that there is a risk of the vehicle colliding with the object detected by the object detection device and that the reliability of the object is equal to or greater than a first reference value, performing collision avoidance control by a control unit to automatically brake the vehicle, The collision avoidance control is a driving assistance method characterized in that, when an object that is likely to collide with the vehicle is located in a predetermined area set at the outer edge of the detection range of the object detection device when viewed from above, and the reliability of the object is determined to be greater than or equal to a second reference value which is smaller than the first reference value, the vehicle is automatically braked at a lower deceleration rate than when it is determined that the object that is likely to collide with the vehicle is located outside the predetermined area within the detection range.

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