Obstacle alarm device for vehicle

Abstract

To provide an obstacle alarm device that can determine whether or not a vehicle is traveling while being positioned in a center between two obstacles in a case where a vehicle travels on a narrow traveling road where obstacles such as barriers are present on both sides.SOLUTION: An obstacle alarm device for a vehicle includes: an alarm emission device that can change an alarm mode; a ranging device that measures a distance between an obstacle near the vehicle and the vehicle; and a drive assist ECU configured to switch the alarm mode in accordance with the distance between the obstacle and the vehicle. The drive assist ECU changes switching conditions for the alarm mode so that switching conditions for the alarm mode at the time when both of a first distance L1 between a first obstacle and a first end part of the vehicle and a second distance L2 between a second obstacle and a second end part of the vehicle are equal to a reference value Lc2 or less are different from switch conditions for the alarm mode at the time when only one of the first distance and the second distance is equal to the reference value or less.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an obstacle warning device for vehicles such as automobiles.

Background Art

[0002] As one of the obstacle warning devices for vehicles such as automobiles, there is known an obstacle warning device configured to issue an alarm when it is determined that the distance between an obstacle and the vehicle is equal to or less than a reference value. For example, Patent Document 1 below describes an obstacle warning device configured to change the mode of the alarm according to the distance between the obstacle and the vehicle and to change the sound pressure of the alarm when the vehicle approaches the obstacle and when the vehicle moves away from the obstacle.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] 〔Problems to be Solved by the Invention〕 In a conventional obstacle warning device such as the device described in Patent Document 1 above, when the distance between the obstacle and the vehicle is equal to or less than the reference value and the distance does not change, the alarm does not change either. For example, when a vehicle is traveling on a narrow road with obstacles such as walls on both sides, an alarm is issued as long as the distance between at least one of the obstacles and the vehicle is equal to or less than the reference value. Therefore, whether the vehicle is approaching only one of the obstacles on both sides or approaching both of the obstacles on both sides, the alarm is the same. Therefore, even if the driver recognizes the alarm, the driver cannot determine whether the vehicle is approaching only one of the obstacles on both sides or approaching both of the obstacles on both sides, that is, whether the vehicle is located at the center between the two obstacles and traveling.

[0005] Incidentally, the above problem also occurs when the host vehicle moves in a situation where there are obstacles such as other vehicles or walls in front of and behind the host vehicle, such as when parking the host vehicle or starting the host vehicle in a parking lot where a plurality of vehicles are parked around.

[0006] The present invention provides an improved obstacle warning device that enables a driver to determine whether a vehicle is traveling at the center between two obstacles when the vehicle travels between two obstacles existing on both sides thereof. [Means for Solving the Problem and Effects of the Invention]

[0007] According to the present invention, there is provided a vehicle obstacle warning device (100) including an alarm device (52) capable of changing an alarm mode, a distance measuring device (sonar device 16) that measures a distance between an obstacle around the vehicle (102) and the vehicle, and a control unit (driving support ECU 10) configured to switch the alarm mode emitted by the alarm device according to the distance between the obstacle and the vehicle measured by the distance measuring device.

[0008] The distance measuring device (sonar device 16) measures a first distance (L1) between a first obstacle and one of a plurality of end portions of the vehicle, which is the end portion closest to the first obstacle, and a second distance (L2) between a second obstacle and the other of the plurality of end portions of the vehicle, which is the end portion closest to the second obstacle. The control unit (driving support ECU 10) is configured to change the alarm mode switching condition (S80, S85) so that the alarm mode switching condition (S80, S85) when both the first and second distances (L1 and L2) are less than or equal to a reference value (Lc2) is different from the alarm mode switching condition (S30, S50) when only one of the first and second distances (L1 or L2) is less than or equal to the reference value.

[0009] According to the above configuration, the switching condition of the warning mode when both the first and second distances are below the reference value is different from the switching condition of the warning mode when only one of the first and second distances is below the reference value. Therefore, even in a situation where the vehicle is traveling between two obstacles that are present on both sides of the vehicle and have a constant and small interval, by appropriately changing the switching condition of the warning mode, it is possible to determine whether the vehicle is approaching only one of the obstacles or approaching both obstacles. 〔Aspect of the Invention〕

[0010] In one aspect of the present invention, before changing the switching condition of the warning mode, the control unit (driving support ECU 10) is configured to switch the warning mode such that when the first or second distance is below the first reference value (Lc1) and greater than the second reference value (Lc2), the warning mode is the first mode (S40), and when the first or second distance is below the second reference value, the warning mode is the second mode (S60).

[0011] In another aspect of the present invention, the control unit (driving support ECU 10) is configured to change the switching condition of the warning mode by changing the second reference value to a smaller value (Lc2') when both the first and second distances (L1 and L2) become below the second reference value (Lc2) (S85).

[0012] In another aspect of the present invention, when the switching condition of the warning mode is changed, the control unit (driving support ECU 10) is configured to switch the warning mode (S70) such that when the magnitude of the difference between the first and second distances is below the reference value of the difference (Lc3), the warning mode is the first mode (S90), and when the magnitude of the difference is greater than the reference value of the difference, the warning mode is the second mode (S100).

[0013] In another aspect of the present invention, when changing the switching condition of the warning mode, the control unit (driving support ECU 10) is configured to notify the driver of the change in the switching condition of the warning mode (S70).

[0014] In the above description, 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 with reference to the following drawings.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0016] The obstacle warning device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0017] As shown in FIG. 1, an obstacle warning device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a drive ECU 20, a brake ECU 30, and a meter ECU 50. ECU means an electronic control unit (Electronic Control Unit) having a microcomputer as a main part.

[0018] The microcomputers of each ECU include a CPU, a ROM, a RAM, a readable and writable non-volatile memory (N / M), and an interface (I / F), etc. The CPU realizes various functions by executing the instructions (programs, routines) stored in the ROM. Further, these ECUs are connected to each other via a CAN (Controller Area Network) 104 so that data can be exchanged (communication is possible). Therefore, the detection values of the sensors (including switches) connected to a specific ECU are also transmitted to other ECUs.

[0019] The driving support ECU 10 is a central control device that performs driving support running control such as obstacle warning control, following vehicle distance control, and lane keeping control. In the embodiment, the driving support ECU 10, as will be described in detail later, cooperates with other ECUs to execute obstacle warning control for the vehicle 102.

[0020] A camera sensor 12, a radar sensor 14, a sonar device 16, and a setting operator 18 are connected to the driving support ECU 10. The camera sensor 12 and the radar sensor 14 each include a plurality of camera devices and a plurality of radar devices, and the sonar device 16 includes a plurality of sonars. The camera sensor 12, the radar sensor 14, and the sonar device 16 function as an obstacle information acquisition device 17 that acquires information on obstacles around the vehicle 102.

[0021] Although not shown in the figure, each camera device of the camera sensor 12 includes a camera unit that photographs the surroundings of the vehicle 102 and a recognition unit that analyzes the image data obtained by the camera unit to recognize object targets such as white lines on the road and other vehicles. The recognition unit supplies information on the recognized object targets to the driving support ECU 10 at predetermined time intervals.

[0022] Each radar device of the radar sensor 14 includes a radar transceiver and a signal processing unit (not shown). The radar transceiver emits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves"), and receives the millimeter waves (i.e., reflected waves) reflected by a three-dimensional object (e.g., another vehicle, a wall, etc.) existing within the radiation range. The signal processing unit is 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 transmitting the millimeter waves to receiving the reflected waves, etc., and supplies information representing the distance between the host vehicle and the three-dimensional object, the relative speed between the host vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object with respect to the host vehicle to the driving support ECU 10 at predetermined time intervals. Note that instead of or in addition to the radar sensor 14, LiDAR (Light Detection And Ranging) may be used.

[0023] The sonar device 16 includes a plurality of sonars, and these sonars are provided at a plurality of positions on the outer periphery of the vehicle 102, for example, the left front corner 102FL, the right front corner 102FR, the left rear corner 102RL, and the right rear corner 102RR. The sonars may also be provided at the front end portion 102F of the vehicle between the left front corner and the right front corner and at the rear end portion 102R of the vehicle between the left rear corner and the right rear corner. Each sonar is configured to transmit ultrasonic waves in a direction away from the vehicle 102, receive the ultrasonic waves (i.e., direct waves) transmitted by its own sonar and reflected by an object, and receive the ultrasonic waves (i.e., indirect waves) transmitted by other sonars and reflected by an object. Further, each sonar is configured to output a signal indicating the peak value of the received voltage corresponding to the received ultrasonic waves, and thus a signal indicating the peak value of the received ultrasonic waves to the control device of the sonar device 16.

[0024] The control device of the sonar device 16 determines that the corresponding sonar is receiving ultrasonic waves when the peak value is equal to or greater than the reference value. Further, the control device of the sonar device 16 estimates the distance between the object that reflected the direct wave and the indirect wave and the vehicle 102 and the direction of the object with respect to the vehicle based on the flight times of the direct wave and the indirect wave. Therefore, the sonar device 16 functions as a ranging device that measures the distance between the obstacles around the vehicle 102 and the vehicle.

[0025] In particular, the sonar device 16 measures a first distance L1 between a first obstacle and a first end of a plurality of ends of the vehicle, which is the one closest to the first obstacle, and a second distance L2 between a second obstacle and a second end of the plurality of ends of the vehicle, which is the other one closest to the second obstacle. The plurality of ends of the vehicle may be a front end, a left front corner, a right front corner, a rear end, a left rear corner, and a right rear corner. Further, the first and second ends may be two ends having a positional relationship such that when the vehicle is displaced relative to the stationary first and second obstacles, one of the first and second distances decreases and the other of the first and second distances increases.

[0026] The setting operator 18 is provided at a position operable by the driver, such as a steering wheel not shown in FIG. 1, and is configured to be operated by the driver. Although not shown in FIG. 1, the setting operator 18 includes an obstacle warning switch. The driving support ECU 10 executes obstacle warning control when the obstacle warning switch is on.

[0027] A drive device 22 for accelerating the vehicle 102 by applying a driving force to the drive wheels 24 is connected to the drive ECU 20. The drive ECU 20 normally controls the drive device 22 so that the driving force generated by the drive device 22 changes according to the driving operation by the driver, and when receiving a command signal from the driving support ECU 10, controls the drive device 22 based on the command signal.

[0028] A braking device 32 for decelerating the vehicle 102 by applying a braking force to the wheels 34 is connected to the braking ECU 30. The braking ECU 30 normally controls the braking device so that the braking force generated by the braking device 32 changes according to the braking operation by the driver, and when receiving a command signal from the driving support ECU 10, performs automatic braking by controlling the braking device 32 based on the command signal.

[0029] The meter ECU 50 is connected to an alarm device 52 that issues an alarm, a touch panel type display 54 that displays the status of control by the driving support ECU 10, etc., and a speaker 56 that gives an audio notification to the driver. When the meter ECU 50 receives a command signal from the driving support ECU 10, the alarm device 52, the display 54, and the speaker 56 are controlled by the meter ECU 50 based on the command signal.

[0030] The alarm device 52 includes an alarm buzzer that emits an audible alarm. The alarm buzzer emits an intermittent sound alarm as a first mode of alarm when the first distance L1 or the second distance L2 is less than or equal to a first reference Lc1 (a positive constant) and greater than or equal to a second reference Lc2 (a positive constant smaller than Lc1). Further, the alarm buzzer emits a continuous sound alarm as a second mode of alarm when the first or second distance is less than or equal to the second reference Lc2. Also, the alarm device 52 may be configured to issue an alarm as one of the collision prevention controls when it is determined that the vehicle 102 may collide with an obstacle. Further, the alarm device 52 may include a visual alarm device such as an alarm lamp, and a tactile alarm device that emits a tactile alarm such as the vibration of the seat.

[0031] The display 54 may be, for example, a multi-information display on which meters and various types of information are displayed, or may be the display of the navigation device described later. As described later, when the display 54 receives a signal from the driving support ECU 10, it displays information related to the obstacle alarm control.

[0032] The driving operation sensor 60 and the vehicle state sensor 70 are also connected to the CAN 104. Information detected by the driving operation sensor 60 and the vehicle state sensor 70 (referred to as sensor information) is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 can be appropriately used in each ECU. Note that the sensor information may be information of a sensor connected to a specific ECU and transmitted from the specific ECU to the CAN 104.

[0033] The driving operation sensor 60 includes a driving operation amount sensor, a braking operation amount sensor, and a brake switch. The driving operation sensor 60 also includes a steering angle sensor, a steering torque sensor, and the like. The vehicle state sensor 70 includes a vehicle speed sensor, a longitudinal acceleration sensor, a lateral acceleration sensor, a yaw rate sensor, and the like. [First Embodiment]

[0034] In the first embodiment, the ROM of the driving support ECU 10 stores an obstacle warning control program corresponding to the flowchart shown in FIG. 2. [First Obstacle Warning Control (FIG. 2)]

[0035] Next, the obstacle warning control in the first embodiment will be described with reference to the flowchart shown in FIG. 2. The obstacle warning control according to the flowchart shown in FIG. 2 is repeatedly executed by the CPU of the driving support ECU 10 at predetermined time intervals in a situation where the obstacle warning switch is on.

[0036] First, in step S10, the CPU outputs a command signal to the meter ECU 50 to display on the display 54 that the obstacle warning control is being executed in the standard mode. Note that this display may be omitted.

[0037] In step S20, the CPU determines whether the first distance L1 or the second distance L2 is less than or equal to the first reference value Lc1. When a negative determination is made, this control returns to step S10, and when an affirmative determination is made, this control proceeds to step S30. Note that when no obstacle is detected by the sonar device 16, a negative determination is made. Further, when a negative determination is made in a situation where an alarm is being issued, the issuance of the alarm is stopped.

[0038] In step S30, the CPU determines whether the first distance L1 or the second distance L2 is less than or equal to the second reference value Lc2. When an affirmative determination is made, this control proceeds to step S50, and when a negative determination is made, this control proceeds to step S40.

[0039] In step S40, the CPU outputs a command signal to the meter ECU 50 to activate the buzzer of the warning device 52, thereby emitting an intermittent sound warning as the warning in the first mode.

[0040] In step S50, the CPU determines whether the first distance L1 and the second distance L2 are less than or equal to the second reference value Lc2. When an affirmative determination is made, this control proceeds to step S70, and when a negative determination is made, this control proceeds to step S60.

[0041] In step S60, the CPU outputs a command signal to the meter ECU 50 to activate the buzzer of the warning device 52, thereby emitting a continuous sound warning as the warning in the second mode.

[0042] In step S70, the CPU outputs a command signal to the meter ECU 50 to display on the indicator 54 that the obstacle warning control is being executed in the narrow mode. Also, when the CPU first executes step S70, the CPU outputs a command signal to the meter ECU 50 to activate the speaker 56 to notify by voice that the obstacle warning control is being executed in the narrow mode. Therefore, both the display by the indicator 54 and the notification by the speaker 56 notify the driver that the obstacle warning control is being executed in the narrow mode.

[0043] In step S80, the CPU calculates a third reference value Lc3 as the product C×(L1 + L2) of a certain coefficient C, for example, between 0.05 and 0.1, and the sum of the distances L1 and L2. The third reference value Lc3 is smaller than the second reference value Lc2. Further, it is determined whether the absolute value of the difference L1 - L2 between the distance L1 and the distance L2 is less than or equal to the third reference value Lc3, that is, whether the distances L1 and L2 are substantially the same. When a negative determination is made, this control proceeds to step S100, and when an affirmative determination is made, this control proceeds to step S90.

[0044] In step S90, the CPU outputs a command signal to the meter ECU 50 to activate the buzzer of the warning device 52, thereby emitting an intermittent sound warning as the warning in the first mode, similar to step S40.

[0045] In step S100, the CPU outputs a command signal to the meter ECU 50 to activate the buzzer of the warning device 52, thereby emitting a continuous sound warning as the warning in the second mode, similar to step S60.

[0046] In step S110, the CPU determines whether the first distance L1 is smaller than the second distance L2. When a negative determination is made, this control proceeds to step S130, and when an affirmative determination is made, this control proceeds to step S120.

[0047] In step S120, the CPU outputs a command signal to the meter ECU 50 to display on the display 54 that the first distance L1 is smaller than the second distance L2, for example, that the side of the first end is narrower than the side of the second end.

[0048] In step S130, the CPU outputs a command signal to the meter ECU 50 to display on the display 54 that the second distance L2 is smaller than the first distance L1, for example, that the side of the second end is narrower than the side of the first end.

[0049] In step S140, the CPU determines whether the first distance L1 or the second distance L2 is less than or equal to the first reference value Lc1, similar to step S20. When a negative determination is made, this control proceeds to step S160, and when an affirmative determination is made, this control proceeds to step S150. Note that in step 140 as well, when no obstacle is detected by the sonar device 16, a negative determination is made.

[0050] In step S150, the CPU determines whether both the first distance L1 and the second distance L2 are equal to or less than a fourth reference value Lc4 (a positive value greater than Lc2 and Lc3 and closer to Lc2 than Lc1). When an affirmative determination is made, this control returns to step S80, and when a negative determination is made, this control proceeds to step S160.

[0051] In step S160, the CPU outputs a command signal to the meter ECU50 to display on the display 54 that the obstacle warning control has returned to the standard mode. Further, the CPU outputs a command signal to the meter ECU50 to activate the speaker 56 to notify audibly that the mode of the obstacle warning control has returned to the standard mode. Thus, both the display on the display 54 and the notification by the speaker 56 notify the driver that the obstacle warning control has returned to the standard mode. <Operation of the First Embodiment>

[0052] <When there is an obstacle in the lateral direction of the vehicle (Fig. 4)> In this case, the obstacle warning control according to the flowchart shown in Fig. 2 is executed. In Fig. 4, the vehicle 102 is traveling on a narrow road 108 between an obstacle 106L such as a left wall and an obstacle 106R such as a right wall. The distance Ll is the distance between the obstacle 106L on the left side of the vehicle 102 and the left front corner of the vehicle, and the distance Lr is the distance between the obstacle 106R on the right side of the vehicle and the right front corner of the vehicle. Assuming the obstacles 106L and 106R are the first and second obstacles, respectively, the left front corner and the right front corner of the vehicle are the first and second ends, respectively, and the distances Ll and Lr are the first and second distances, respectively. (Case of (A))

[0053] As shown in Fig. 4(A), when the distance Ll or Lr is equal to or less than the first reference value Lc1 and both the distances Ll and Lr are greater than the second reference value Lc2, affirmative determination and negative determination are made in steps S20 and S30, respectively. Thus, in step S40, an intermittent sound alarm is issued. (Case of (B))

[0054] As shown in FIG. 4(B), when one of the distances Ll and Lr is equal to or less than the second reference value Lc2 and the other of the distances Ll and Lr is greater than the second reference value Lc2, in steps S20 and S30, an affirmative determination is made, and in step S50, a negative determination is made. Therefore, in step S60, a continuous sound alarm is issued.

[0055] In addition, in the cases of (A) and (B) above, the mode of the obstacle warning control is set to the standard mode, and this is notified. (C) case

[0056] As shown in FIG. 4(C), when both of the distances Ll and Lr are equal to or less than the second reference value Lc2, in steps S20, S30, and S50, an affirmative determination is made. Therefore, in step S70, it is displayed on the display 54 that the obstacle warning control is executed in the narrow mode, and this is notified.

[0057] In particular, when the magnitude of the difference between the distance Ll and the distance Lr is equal to or less than the third reference value Lc3, in step S80, an affirmative determination is made. Therefore, in step S90, an intermittent sound alarm is issued and the speaker 56 is activated, whereby it is notified by voice that the obstacle warning control is executed in the narrow mode.

[0058] By recognizing that the mode of the obstacle warning control is the narrow mode and the intermittent sound alarm is being issued, the driver can recognize that both of the distances Ll and Lr are equal to or less than the second reference value Lc2 and they are substantially the same, and thus the vehicle is traveling substantially in the center of the traveling road 108. (D) case

[0059] When both the distances Ll and Lr are less than or equal to a second reference value Lc2 and the magnitude of the difference between the distance Ll and the distance Lr is greater than a third reference value Lc3, a negative determination is made in step S80. Therefore, in step S100, a continuous sound alarm is issued.

[0060] In particular, as shown in FIG. 4(D), when the distance Ll is smaller than Lr, an affirmative determination is made in step S110, and in step S120, it is displayed on the display 54 that the left distance Ll is smaller than the right distance Lr.

[0061] Conversely, when the distance Ll is greater than Lr, a negative determination is made in step S110, and in step S130, it is displayed on the display 54 that the right distance Lr is smaller than the left distance Ll.

[0062] The driver recognizes that the obstacle warning control mode is the narrow mode and a continuous sound alarm is being issued, and by looking at the display on the display 54, the driver can recognize that both the distances Ll and Lr are less than or equal to the second reference value Lc2 and which of the distances Ll and Lr is smaller than the other. That is, the driver can recognize that the vehicle is deviating and traveling to either the left or right side from the center of the traveling road 108.

[0063] Note that as the vehicle 102 travels, the interval between the left obstacle 106L and the right obstacle 106R increases, and when one of the distances Ll and Lr becomes greater than a fourth reference value Lc4, a negative determination is made in step S150. Also, when both the distances Ll and Lr become greater than a first reference value Lc1, a negative determination is made in step S140. In these cases, in step S160, it is notified that the obstacle warning control returns to the standard mode. <When there are obstacles in the front-rear direction of the vehicle (FIG. 5)>

[0064] FIG. 5 shows a situation where the vehicle is reversing from one of two parallel parking spaces when there are obstacles in the front-rear direction of the vehicle 102. In FIG. 5, the distance Lf is the shortest distance between another vehicle 110 as an obstacle in front of the vehicle 102 and the right front corner of the vehicle, and the distance Lb is the shortest distance between another vehicle 112 as an obstacle behind the vehicle and the right rear corner of the vehicle. Regarding the other vehicles 110 and 112 as the first and second obstacles respectively, the right front corner and the right rear corner of the vehicle are the first and second ends respectively, and the distances Lf and Lb are the first and second distances respectively.

[0065] When the distance Lf or Lb is less than or equal to the first reference value Lc1 and both the distances Lf and Lb are greater than the second reference value Lc2, in steps S20 and S30, a positive determination and a negative determination are made respectively. Therefore, in step S40, an intermittent sound alarm is issued.

[0066] When one of the distances Lf and Lb is less than or equal to the second reference value Lc2 and the other of the distances Lf and Lb is greater than the second reference value Lc2, in steps S20 and S30, a positive determination is made, and in step S50, a negative determination is made. Therefore, in step S60, a continuous sound alarm is issued.

[0067] When both the distances Lf and Lb are less than or equal to the second reference value Lc2, in steps S20, S30, and S50, a positive determination is made. Therefore, in step S70, it is displayed on the display 54 that the obstacle alarm control is executed in the narrow mode, and this is notified.

[0068] In particular, when the magnitude of the difference between the distance Lf and the distance Lb is less than or equal to the third reference value Lc3, in step S80, a positive determination is made. Therefore, in step S90, an intermittent sound alarm is issued and the speaker 56 is activated, so that it is notified by voice that the obstacle alarm control is executed in the narrow mode, and this is notified.

[0069] By recognizing that the mode of the obstacle warning control is the narrow mode and an intermittent sound warning is being issued, the driver can recognize that both the distances Lf and Lb are equal to or less than a second reference value Lc2 and they are substantially the same. Therefore, it can be recognized that the vehicle 102 is positioned substantially at the center of the space between the vehicle 110 in front and the vehicle 112 behind.

[0070] When both the distances Lf and Lb are equal to or less than a second reference value Lc2 and the magnitude of the difference between the distance Lf and the distance Lb is greater than a third reference value Lc3, a negative determination is made in step S80. Therefore, in step S100, a continuous sound warning is issued.

[0071] In particular, when the distance Lf is smaller than Lb, an affirmative determination is made in step S110, and in step S120, it is displayed on the display 54 that the front distance Lf is narrower than the rear distance Lb.

[0072] Conversely, when the distance Lb is smaller than Lf, a negative determination is made in step S110, and in step S130, it is displayed on the display 54 that the rear distance Lb is narrower than the front distance Lf.

[0073] By recognizing that the mode of the obstacle warning control is the narrow mode and a continuous sound warning is being issued and by looking at the display on the display 54, the driver can recognize that both the distances Lf and Lb are equal to or less than a second reference value Lc2 and one of the distances Lf and Lb is smaller than the other, and can recognize whether the vehicle is approaching either the vehicle 110 in front or the vehicle 112 behind.

[0074] Incidentally, when the distance between the vehicle 102 and the other vehicle in front or the distance between the vehicle 102 and the other vehicle behind increases as the vehicle 102 moves, and either the distance Lf or the distance Lb becomes greater than the fourth reference value Lc4, a negative determination is made in step S150. Also, when both the distances Lf and Lb become greater than the first reference value Lc1, a negative determination is made in step S140. In these cases, in step S160, it is displayed on the display 54 that the obstacle warning control returns to the standard front-rear direction mode, and the speaker 56 is activated to notify by voice that the mode of the obstacle warning control returns to the standard mode. [Second Embodiment]

[0075] In the second embodiment, the ROM of the driving support ECU 10 stores an obstacle warning control program corresponding to the flowchart shown in FIG. 3. The obstacle warning control according to the flowchart shown in FIG. 3 is also repeatedly executed by the CPU of the driving support ECU 10 at predetermined time intervals in a situation where the obstacle warning switch is on.

[0076] As understood from the comparison between FIG. 3 and FIG. 2, steps S10 to S70 and steps S90 to S160 are executed in the same manner as in the first embodiment. However, when step S70 is completed, this control proceeds to step S85.

[0077] In step S85, the CPU determines whether the first distance L1 or the second distance L2 is less than or equal to the second reference value Lc2' (a positive constant smaller than the second reference value Lc2) after the change. When a negative determination is made, this control proceeds to step S90, and when a positive determination is made, this control proceeds to step S100.

[0078] According to the second embodiment, when the first distance L1 and the second distance L2 are equal to or less than the second reference value Lc2 and the mode of the obstacle warning control is changed to the narrow mode, in step S85, it is determined whether the distance L1 or L2 is equal to or less than the changed second reference value Lc2'. When the distances L1 and L2 are greater than the changed second reference value Lc2', in step S90, an intermittent sound alarm is issued. On the other hand, when the distance L1 or L2 is equal to or less than the changed second reference value Lc2', in step S100, a continuous sound alarm is issued. <Effects of the First and Second Embodiments>

[0079] According to the first and second embodiments, the switching conditions (S80, S85) of the alarm mode when both the first distance L1 and the second distance L2 are equal to or less than the reference value Lc2 are different from the switching conditions (S30, S50) of the alarm mode when only one of the first distance L1 and the second distance L2 is equal to or less than the reference value. Therefore, even when the vehicle is traveling between the first and second obstacles with a small interval, by appropriately changing the switching conditions of the alarm mode (intermittent sound or continuous sound), it is possible to determine whether the vehicle is approaching only one obstacle, that is, whether the vehicle is traveling at the center between the two obstacles.

[0080] Also, according to the first and second embodiments, when it is determined that both the first distance L1 and the second distance L2 are equal to or less than the second reference value Lc2 (S50), it is displayed on the display 54 that the mode of the obstacle warning control is the narrow mode, and it is notified by voice (S70). Therefore, the driver can recognize whether the mode of the obstacle warning control is the standard mode or the narrow mode.

[0081] Furthermore, according to the first and second embodiments, before the switching condition of the alarm mode is changed, when the first distance L1 or the second distance L2 is less than or equal to the first reference value Lc1 and greater than the second reference value Lc2, the alarm mode is the first mode (intermittent sound, S40), and when the first or second distance is less than or equal to the second reference value, the alarm mode is switched so that it is the second mode (continuous sound, S60). Therefore, when the alarm mode is the second mode, the driver can determine that the first or second distance is smaller than when the alarm mode is the first mode, and the vehicle is approaching the corresponding obstacle.

[0082] Also, according to the first embodiment, when the absolute value of the difference L1 - L2 between the first distance L1 and the second distance L2 is less than or equal to the third reference value Lc3 (S80), in a situation where it is notified that the mode of the obstacle alarm control is the narrow mode (S70), an intermittent sound alarm is issued as the alarm of the first mode (S90). On the other hand, when the absolute value of the difference L1 - L2 exceeds the third reference value Lc3, in a situation where it is notified that the mode of the obstacle alarm control is the narrow mode, a continuous sound alarm is issued as the alarm of the second mode (S100).

[0083] Therefore, by recognizing the content of the notification and the alarm sound, the driver can determine that both the first distance L1 and the second distance L2 are less than or equal to the second reference value Lc2 before the change, and whether the vehicle is located at the center between the two obstacles or the vehicle is approaching one of the two obstacles.

[0084] Furthermore, according to the first embodiment, when the magnitude of the difference is greater than the reference value Lc3 of the difference, when the first distance L1 is smaller than the second distance L2, it is displayed on the display 54 that the first distance L1 is smaller than the second distance L2 (S120). Conversely, when the first distance L1 is not smaller than the second distance L2, it is displayed on the display 54 that the second distance L2 is smaller than the first distance L1 (S120).

[0085] Therefore, by recognizing the content of the notification and the warning sound, the driver can recognize that both the first distance L1 and the second distance L2 are equal to or less than the second reference value Lc2, and which of the first and second ends is approaching the corresponding obstacle.

[0086] Furthermore, according to the second embodiment, when both the first distance L1 and the second distance L2 become equal to or less than the second reference value Lc2, the switching condition of the warning mode is changed by changing the second reference value to a smaller value Lc2' (S85). Therefore, in a situation where the obstacle warning control mode is the narrow mode, the driver can determine whether the vehicle is traveling substantially at the center between the first and second obstacles, and whether the warning mode is either the first or second mode, and can determine whether the vehicle is approaching either one of the first and second obstacles.

[0087] Also, according to the second embodiment, when the first distance L1 is smaller than the second distance L2, it is displayed on the display 54 that the first distance L1 is smaller than the second distance L2 (S120). Conversely, when the first distance L1 is not smaller than the second distance L2, it is displayed on the display 54 that the second distance L2 is smaller than the first distance L1 (S120).

[0088] Therefore, by recognizing the content of the notification and the warning sound, the driver can recognize that both the first distance L1 and the second distance L2 are equal to or less than the second reference value Lc2, and which of the first and second ends is approaching the corresponding obstacle.

[0089] Further, according to the first and second embodiments, when the obstacle warning control is changed from the standard mode to the narrow mode and the switching condition of the warning mode is changed, the change in the switching condition of the warning mode is notified to the driver in step S70. Therefore, the driver can recognize whether the switching condition of the warning mode has changed, that is, whether the control mode is the standard mode or the narrow mode. Therefore, by recognizing the control mode, not only when the vehicle travels between the first and second obstacles with a constant and small interval, but also when the vehicle travels between the first and second obstacles with a small and changing interval, by determining the warning mode (intermittent sound or continuous sound), it is possible to determine whether the vehicle is approaching only one obstacle, that is, whether the vehicle is traveling in the center between the two obstacles.

[0090] Furthermore, according to the first and second embodiments, the warning sounds emitted in steps S40 and S90 are intermittent sounds, and the warning sounds emitted in steps S60 and S100 are continuous sounds. Therefore, compared with the case where the warning sounds emitted in steps S40 and S90 are different from each other and the warning sounds emitted in steps S60 and S100 are different from each other, since the modes of the warning sounds are fewer, it is possible to reduce the risk that the driver makes an error due to the large number of warning sound modes.

[0091] In the above, the present invention has been described in detail with respect to specific embodiments, but it is obvious to those skilled in the art that the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention.

[0092] For example, in the above-described first and second embodiments, in step S110, it is determined whether the first distance L1 is smaller than the second distance L2, and in steps S120 and S130, which of the distances L1 and L2 is smaller is displayed on the display 54. However, steps S110 to S130 may be omitted.

[0093] Also, in the above-described first and second embodiments, the warning sounds emitted in steps S40 and S90 are intermittent sounds, and the warning sounds emitted in steps S60 and S100 are continuous sounds. However, the warning sounds emitted in steps S40 and S90 may be different from each other, and the warning sounds emitted in steps S60 and S100 may also be different from each other.

Description of Reference Numerals

[0094] 10… Driving support ECU, 12… Camera sensor, 14… Radar sensor, 16… Sonar device, 17… Target information acquisition device, 22… Driving device, 32… Braking device, 52… Warning emission device, 54… Display, 56… Speaker, 100… Obstacle warning device, 102… Vehicle, 104, 106… Obstacles

Claims

1. An obstacle warning device for a vehicle, comprising: an alarm device capable of changing an alarm mode; a distance measuring device that measures a distance between an obstacle around the vehicle and the vehicle; and a control unit configured to switch the alarm mode emitted by the alarm device according to the distance between the obstacle measured by the distance measuring device and the vehicle. The distance measuring device measures a first distance between a first obstacle and a first end portion, which is one of a plurality of end portions of the vehicle and is closest to the first obstacle, and a second distance between a second obstacle and a second end portion, which is another one of the plurality of end portions of the vehicle and is closest to the second obstacle. The control unit is configured to change the switching condition of the alarm mode such that the switching condition of the alarm mode when both the first and second distances are less than or equal to the reference value is different from the switching condition of the alarm mode when only one of the first and second distances is less than or equal to the reference value.

2. In the obstacle warning device for a vehicle according to Claim 1, before changing the switching condition of the alarm mode, the control unit is configured to switch the alarm mode such that when the first or second distance is less than or equal to a first reference value and greater than a second reference value, the alarm mode is a first mode, and when the first or second distance is less than or equal to the second reference value, the alarm mode is a second mode.

3. In the obstacle warning device for a vehicle according to Claim 2, when both the first and second distances become less than or equal to the second reference value, the control unit is configured to change the switching condition of the alarm mode by changing the second reference value to a smaller value.

4. In the vehicle obstacle warning device according to claim 2, when the control unit changes the switching condition of the warning mode, if the magnitude of the difference between the first and second distances is less than or equal to the reference value of the difference, the warning mode is the first mode, and if the magnitude of the difference is greater than the reference value of the difference, the warning mode is switched so that the warning mode is the second mode. A vehicle obstacle warning device configured as such.

5. In the vehicle obstacle warning device according to claim 1, when the control unit changes the switching condition of the warning mode, the control unit is configured to notify the driver of the change in the switching condition of the warning mode. A vehicle obstacle warning device.

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