Driving assistance device

Abstract

The present invention is configured to include: a triangulation area 17 in which the position of an object is specified by a triangulation using a first detected distance calculated by an ultrasonic sensor receiving a probe wave transmitted by the ultrasonic sensor itself as a direct wave and a second detected distance calculated by the ultrasonic sensor receiving a probe wave transmitted from another ultrasonic sensor as an indirect wave; and a direct wave area 18 in which the position of the object is specified only by the first detected distance, wherein the display of a warning image 52 in the direct wave area 18 is restricted under a prescribed condition.

Description

Driving assistance devices

[0001] The present invention relates to a driving assistance device that assists driving of a vehicle.

[0002] BACKGROUND ART Conventionally, as a safety device for ensuring safety when a vehicle is driving or parking, there has been known a technology in which detection sensors such as ultrasonic sensors, millimeter wave radar sensors, LiDAR sensors, etc. are arranged on the vehicle to detect surrounding objects (e.g., people, bicycles, other vehicles, walls, etc.), and a warning is given to the driver or the vehicle is automatically controlled based on the detection results of the detection sensors.

[0003] Such detection sensors emit probe waves, such as ultrasonic waves, millimeter waves, or infrared waves, and measure the time it takes for the emitted probe waves to reflect off an object and return to detect the distance to the object. Furthermore, by arranging multiple detection sensors on a vehicle, it becomes possible to use indirect waves in addition to direct waves, enabling more accurate detection of objects. Note that "direct waves" refer to the received waves when the detection sensor that transmitted the probe waves is the same as the detection sensor that received the reflected waves from the object. On the other hand, "indirect waves" refer to the received waves when the detection sensor that transmitted the probe waves is different from the detection sensor that received the reflected waves from the object. For example, Japanese Patent Publication No. 7167675 discloses a technology for detecting the position of an object by triangulation using the detection distances detected by direct waves and indirect waves, in which multiple detection sensors are arranged on a vehicle.

[0004] Patent No. 7167675 (paragraphs 0021-0043)

[0005] To detect an object using direct and indirect waves as in Patent Document 1, it is necessary to arrange multiple detection sensors 101-104 side by side at a distance that allows them to receive indirect waves from each other, as shown in Figure 13. However, when the detection sensors 101-104 are arranged side by side, within the detection range in which the detection sensors 101-104 can detect an object, areas (hereinafter referred to as direct wave areas 105) are created at both ends of the detection range in which only the detection sensors 101 and 104 located at the ends can receive reflected waves from the object in that area. In such direct wave areas 105, object detection using indirect waves is not possible, and triangulation cannot be used. Therefore, object detection is performed only based on the detection distance measured using direct waves. However, while direct wave detection can measure the distance to the object, it is difficult to identify its specific location. Therefore, even if an object is detected using direct waves, it is impossible to determine whether the object is in the direct wave area 105 or in an area where triangulation can be used (hereinafter referred to as triangulation area 106).

[0006] Therefore, it is conceivable that only when triangulation using direct waves and indirect waves is not successful within the detection ranges of the detection sensors 101 and 104 arranged outside, i.e., when it is confirmed that no object is present in the triangulation area 106 within the detection ranges of the detection sensors 101 and 104 due to unsuccessful triangulation, and when an object can be detected using direct waves, it is assumed that the object is present in the direct wave area 105, and a warning is issued about the object in the direct wave area 105. However, when triangulation is not successful, it does not only include cases where direct waves or indirect waves cannot be received, but also cases where triangulation points cannot be calculated even when direct waves and indirect waves are received. Furthermore, in situations where detection by the detection sensors 101 to 104 is difficult, such as when the object has a curved surface, triangulation may not be successful even if the object is present in the triangulation area 106. Even in such a case, if the direct wave is received and a warning is issued that there is an object in the direct wave area 105, it is possible that, even though an object actually exists in the triangulation area 106, no warning is issued in the triangulation area 106 and a warning is issued in the direct wave area 105 where there is no object, as shown in Fig. 14. As a result, when issuing a warning about an object, there are gaps in the warning, resulting in a problem in which the warning is issued as if there were multiple objects.

[0007] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide a driving assistance device that, when issuing a warning about an object, does not issue a warning that is strange to the user or that contains incorrect information.

[0008] In order to achieve the above object, the driving assistance device according to the present invention comprises a first detection sensor and a second detection sensor, which are respectively installed at different locations relative to the vehicle and positioned so as to transmit probe waves around the vehicle and to mutually receive received waves including waves reflected by objects around the vehicle from the first detection sensor and a second detection sensor, a surrounding image display means for displaying a surrounding image showing the surroundings of the vehicle on a display device, an object determination means for dividing the surroundings of the vehicle into a plurality of areas for each direction centered on the current position of the vehicle and determining whether or not the object is located in each of the divided areas using the detection results of at least one of the first detection sensor and the second detection sensor, and a detection control means for determining whether or not the object is located in each of the divided areas using the detection results of at least one of the first detection sensor and the second detection sensor. and a warning image display means for displaying a warning image indicating the location of the object in the peripheral image for an area determined to be a target of the detection of the object. The divided areas include a triangulation area in which the location of the object is identified by triangulation using a first detection distance calculated by receiving the detection wave transmitted by the first detection sensor as a direct wave and a second detection distance calculated by receiving the detection wave transmitted from the first detection sensor as an indirect wave, and a direct wave area in which the location of the object is identified only by the first detection distance. The warning image display means limits the display of the warning image in the direct wave area under a predetermined condition. Note that the "periphery image showing the vehicle's surroundings" may be an actual captured image of the vehicle's surroundings, or may be an image obtained by processing the captured image, or may be a created CG image rather than an actual captured image. Furthermore, the created image does not necessarily have to be an image faithfully reproducing the vehicle's surroundings.

[0009] According to the driving assistance device of the present invention having the above-described configuration, the display of a warning image in a direct wave area that identifies the position of an object based on the detection distance detected by direct waves under specified conditions is restricted, so that when issuing a warning about an object, it is possible to prevent the user from receiving a warning that is strange or contains incorrect information.

[0010] 1 is a schematic configuration diagram of a vehicle according to the present embodiment. FIG. 1 is a diagram showing an example of the arrangement of ultrasonic sensors on the front of the vehicle. FIG. 2 is a diagram showing an example of the arrangement of ultrasonic sensors on the side of the vehicle. FIG. 3 is a diagram explaining a method of identifying the specific position (relative position with respect to the vehicle) of an object using triangulation. FIG. 4 is a diagram showing triangulation areas and direct wave areas. FIG. 5 is a diagram explaining a method of detecting an object using only direct waves. FIG. 6 is a block diagram showing the configuration of a driving assistance device according to the present embodiment. FIG. 7 is a flowchart of a driving assistance processing program according to the present embodiment. FIG. 8 is a diagram showing each divided area when the periphery of a vehicle is divided. FIG. 9 is a diagram explaining a case where triangulation is not successful. FIG. 10 is a diagram showing an example of a warning image displayed when triangulation is successful. FIG. 11 is a diagram explaining a problem of the prior art.

[0011] A detailed description will be given below of a specific embodiment of a driving assistance device according to the present invention with reference to the drawings. First, a vehicle 2 equipped with a driving assistance device 1 according to this embodiment will be described. Fig. 1 is a schematic diagram of the vehicle 2 according to this embodiment.

[0012] Here, the vehicle 2 may be, for example, an automobile (internal combustion engine automobile) that uses an internal combustion engine (engine, etc.) as a drive source, an automobile (electric automobile, fuel cell automobile, etc.) that uses an electric motor (motor, etc.) as a drive source, or an automobile that uses both of these as drive sources (hybrid automobile). Furthermore, the vehicle type is not limited, and may be a standard car, a large commercial truck, a bus, construction machinery, or the like. Furthermore, although the following description will be of a four-wheeled automobile, it may also be a two-wheeled or three-wheeled vehicle.

[0013] However, vehicle 2 is a vehicle capable of manual driving, in which the vehicle drives based on the user's driving operation, as well as assisted driving using automatic driving assistance, in which the vehicle drives automatically without the user's driving operation.

[0014] Furthermore, the autonomous driving assistance may be performed only under specific circumstances, such as when parking or leaving a parking lot, or may be performed for all road sections, or may be performed only while the vehicle is traveling on a specific road section (for example, a highway with a gate (manned or unmanned, toll or free) at the boundary). In the following description, the autonomous driving section in which the autonomous driving assistance of the vehicle is performed includes all road sections, including general roads and highways, as well as parking lots. Furthermore, the autonomous driving assistance is performed only when the user selects to perform the autonomous driving assistance (for example, by turning on the autonomous driving start button) and it is determined that autonomous driving assistance is possible. On the other hand, the vehicle 2 may be a vehicle that is only capable of assisted driving with autonomous driving assistance. Alternatively, the autonomous driving assistance may be performed only when the vehicle is traveling to a parking space when parking (i.e., parking assistance).

[0015] In the vehicle control for the automated driving assistance of this embodiment, for example, the current position of the vehicle, the lane the vehicle is traveling on, and the positions of surrounding obstacles are detected as needed, and vehicle control of the steering, drive source, brakes, etc. is automatically performed so that the vehicle travels along the generated travel trajectory at a speed in accordance with the generated speed plan. In particular, when performing parking assistance, as described below, a parking space for parking the vehicle is identified using detection results from sensors and cameras, a parking trajectory to the identified parking space is calculated, and the vehicle is automatically controlled to enter the parking space along the calculated parking trajectory and complete parking. However, only the steering operation may be performed automatically, and the drive source and brakes may be controlled manually. Alternatively, only parking space guidance may be provided, and the user may manually park into the parking space. Furthermore, when performing the automated driving assistance, a scene (actual scene) around the vehicle captured by a camera installed in the vehicle is displayed on an in-vehicle display. If there is an object around the vehicle that the user should pay attention to, such as another vehicle, a warning image indicating the presence of the object is superimposed on the scene.

[0016] 1, the vehicle 2 has an operation unit 3 that accepts operations from the occupant, a liquid crystal display 4 that displays bird's-eye and overhead images of the vehicle's surroundings and other information related to driving assistance to the occupant, a speaker 5 that outputs audio guidance related to driving assistance, a front camera 6, a rear camera 7, and side cameras 8A and 8B for capturing images of the vehicle's surroundings, ultrasonic sensors 9A to 9L that detect obstacles around the vehicle, and a driving assistance ECU (electronic control unit) 10 that performs various calculations based on input information. The driving assistance ECU 10 and other components are collectively referred to as a driving assistance device 1.

[0017] Each component of the vehicle 2 will be described below. First, the operation unit 3 is arranged, for example, on the front of the steering wheel (also called the steering wheel), and includes an operation button that is operated when starting automatic driving assistance. By operating the operation unit 3, the user can switch between manual driving, in which the vehicle drives based on the user's driving operation, and automatic driving assistance, in which the vehicle drives automatically without the user's driving operation. The operation unit 3 may have a touch panel provided on the front of the liquid crystal display 4. It may also have a microphone and a voice recognition device.

[0018] The liquid crystal display 4 is mounted on the instrument panel of the vehicle 2, and displays bird's-eye and overhead images of the vehicle's surroundings generated by performing viewpoint conversion and synthesis processing on images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B during autonomous driving assistance. Furthermore, if there is an object around the vehicle that the user should pay attention to, such as another vehicle, the liquid crystal display 4 also displays a warning image indicating the presence of the object in the bird's-eye and overhead images. The liquid crystal display 4 may also be used for a navigation device.

[0019] The speaker 5 is mounted on the instrument panel of the vehicle 2 and outputs voice guidance and warning sounds related to driving assistance. In particular, when an object approaches the vehicle, a warning sound for the object is output in a manner that indicates the direction in which the object is located. The speaker 5 may also be used for a navigation device.

[0020] The forward camera 6 is an imaging device having a camera using a solid-state imaging element such as a CCD, and is installed, for example, above the front bumper of the vehicle 2 or behind the rearview mirror, with its optical axis facing forward in the direction of travel of the vehicle.

[0021] The rear camera 7 is an imaging device having a camera that also uses a solid-state imaging element such as a CCD, and is installed, for example, near the upper center of the license plate attached to the rear of the vehicle 2, with its optical axis facing toward the rear of the vehicle.

[0022] Furthermore, the side cameras 8A and 8B are imaging devices having cameras that similarly use solid-state imaging elements such as CCDs, and are installed, for example, on the left and right side mirrors of the vehicle 2 with their optical axes facing out to the sides of the vehicle.

[0023] The driving assistance ECU 10 generates bird's-eye and overhead images of the surroundings of the vehicle by performing viewpoint conversion and synthesis processing on the images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B. During execution of autonomous driving assistance, the driving assistance ECU 10 also performs image recognition processing on the captured images to detect lane lines, parking frame lines, and obstacles (other vehicles, pedestrians, bicycles, walls, guardrails, and other structures) around the vehicle, and executes autonomous driving assistance based on the detection results.

[0024] Meanwhile, ultrasonic sensors 9A-9L are positioned at predetermined intervals on the front, rear, and sides of the vehicle 2. They transmit ultrasonic waves as search waves around the vehicle 2 and receive reflected waves from surrounding objects to detect the objects that reflect the search waves. Specifically, they are a type of distance measurement sensor that can measure the distance (measured distance) to the object that reflected the search wave by measuring the time from transmission to reception. Furthermore, ultrasonic sensors 9A-9L are configured to generate output signals (including the distance to the detected object) corresponding to the reception results of the received waves and output them to the control unit. Note that objects detected by ultrasonic sensors 9A-9L include, for example, obstacles that the vehicle 2 must avoid when traveling, such as people, bicycles, other vehicles, and walls, or obstacles that form parking spaces. Note that millimeter-wave sensors or radar sensors may be used as distance measurement sensors instead of ultrasonic sensors.

[0025] The installation position and installation direction of each ultrasonic sensor 9A-9L can be set as appropriate. In this embodiment, in order to detect objects in all directions (forward, backward, left, and right) of the vehicle 2, for example, ultrasonic sensors 9A-9D are installed on the front of the vehicle 2 facing the direction of travel so that the transmission direction of the search wave is forward of the vehicle's direction of travel. Ultrasonic sensors 9E and 9F are installed on the left side of the vehicle 2 facing left so that the transmission direction of the search wave is to the left of the vehicle's direction of travel. Ultrasonic sensors 9G and 9H are installed on the right side of the vehicle 2 facing right so that the transmission direction of the search wave is to the right of the vehicle's direction of travel. Ultrasonic sensors 9I-9L are installed on the rear of the vehicle 2 facing in the opposite direction to the vehicle's direction of travel so that the transmission direction of the search wave is to the rear of the vehicle. The heights of each ultrasonic sensor 9A-9L from the ground surface are approximately the same.

[0026] Taking ultrasonic sensors 9A to 9D as an example, it is desirable that ultrasonic sensors 9A to 9D be installed at different positions around the front bumper or the front grille above the front bumper of vehicle 2, as shown in Figure 2, at equal intervals without bias in the left and right directions, so that detection waves can be transmitted over a wider range in front of the vehicle (i.e., the range in which objects can be detected is wider).

[0027] Specifically, as shown in FIG. 2 , ultrasonic sensor 9A is installed near the left front corner of vehicle 2 with the transmission direction of the probe wave tilted slightly leftward from the direction of travel of vehicle 2 so as to transmit the probe wave to the left front of vehicle 2. Ultrasonic sensor 9B is installed slightly left of the center line of vehicle 2 with the transmission direction of the probe wave tilted toward the direction of travel of the vehicle so as to transmit the probe wave mainly from the front, particularly the left side of vehicle 2. Ultrasonic sensor 9C is installed slightly right of the center line of vehicle 2 with the transmission direction of the probe wave tilted toward the direction of travel of the vehicle so as to transmit the probe wave mainly from the front, particularly the right side of vehicle 2. Ultrasonic sensor 9D is installed near the right front corner of vehicle 2 with the transmission direction of the probe wave tilted slightly rightward from the direction of travel of vehicle 2 so as to transmit the probe wave to the right front of vehicle 2. Ultrasonic sensors 9A and 9D, and ultrasonic sensors 9B and 9C are each arranged symmetrically across the vehicle center line in a plan view. Although not shown, the ultrasonic sensors 9I to 9L on the rear surface of the vehicle 2 are similarly arranged in a vertically symmetrical manner.

[0028] 3, the ultrasonic sensors 9E and 9F on the sides are each installed so as to emit search waves in a direction that intersects at 90 degrees with the direction of travel of the vehicle 2. Since there are fewer sensors installed relative to the range on the sides compared to the front and rear of the vehicle as described above, there are areas where the ultrasonic sensors 9E and 9F cannot directly detect objects. However, in these areas, it is possible to estimate the presence or location of objects from the object detection history of the ultrasonic sensors 9A to 9L. Although not shown, the ultrasonic sensors 9G and 9H on the right side of the vehicle 2 are similarly installed, with left-right symmetry.

[0029] In this embodiment, among the ultrasonic sensors 9A-9L, the ultrasonic sensors 9A-9D on the front of the vehicle 2 and the ultrasonic sensors 9I-9L on the rear of the vehicle 2 are particularly installed in positions where they can receive reflected waves from adjacent sensors as indirect waves, so that by receiving direct and indirect waves as received waves, it is possible to determine not only the distance to an object but also the specific position of the object (its relative position with respect to the vehicle) using triangulation. The ultrasonic sensors 9E-9H on the sides are installed at a distance from each other and therefore cannot receive indirect waves, but as the vehicle moves, it is possible to determine the specific position of the object (its relative position with respect to the vehicle) by triangulation using the measured distance at the previous position, the measured distance at the current position, and the distance traveled between them.

[0030] The following description will be given in more detail, including the manner of detecting objects, using the ultrasonic sensors 9A-9D arranged on the front of the vehicle 2 as an example. Among the ultrasonic sensors 9A-9D, the ultrasonic sensor 9A and the ultrasonic sensor 9B are at least positioned so that they can receive each other's incoming waves. That is, the ultrasonic sensor 9B is positioned so that it can receive the search wave transmitted by the ultrasonic sensor 9A as an indirect wave. Similarly, the ultrasonic sensor 9A is positioned so that it can receive the search wave transmitted by the ultrasonic sensor 9B as an indirect wave. Furthermore, the ultrasonic sensors 9B and 9C are also positioned so that they can receive each other's incoming waves. That is, the ultrasonic sensor 9C is positioned so that it can receive the search wave transmitted by the ultrasonic sensor 9B as an indirect wave. Similarly, the ultrasonic sensor 9B is positioned so that it can receive the search wave transmitted by the ultrasonic sensor 9C as an indirect wave. Furthermore, the ultrasonic sensors 9C and 9D are also positioned so that they can receive each other's incoming waves. That is, the ultrasonic sensor 9D is positioned so that it can receive the search wave transmitted by the ultrasonic sensor 9C as an indirect wave. Similarly, the ultrasonic sensor 9C is positioned so as to be able to receive the search wave transmitted by the ultrasonic sensor 9D as an indirect wave.

[0031] On the other hand, for combinations of ultrasonic sensors other than those described above, they are basically in a positional relationship where they cannot receive each other's received waves. For example, ultrasonic sensors 9C and 9D are in a positional relationship where they cannot receive as indirect waves the search wave transmitted by ultrasonic sensor 9A. Also, ultrasonic sensor 9D is in a positional relationship where it cannot receive as indirect waves the search wave transmitted by ultrasonic sensor 9B. Also, ultrasonic sensor 9A is in a positional relationship where it cannot receive as indirect waves the search wave transmitted by ultrasonic sensor 9C. Also, ultrasonic sensors 9A and 9B are in a positional relationship where they cannot receive as indirect waves the search wave transmitted by ultrasonic sensor 9D.

[0032] The above phrase "receiving a received wave" means that the received wave can be received to an extent that the distance to the target can be effectively detected, whereas "receiving a received wave cannot be received" includes not only the inability to receive any received wave but also the reception strength being so weak that the distance to the target cannot be effectively detected.

[0033] In this embodiment, the ultrasonic sensors 9A-9D receive direct and indirect waves as received waves, enabling them to determine not only the distance to an object but also its specific location (relative to the vehicle). The terms "direct wave" and "indirect wave" are defined as follows. For example, among the received waves received by ultrasonic sensor 9A, the received wave resulting from the reflection of the search wave transmitted from ultrasonic sensor 9A by the object is referred to as a "direct wave." A direct wave is a received wave received by ultrasonic sensor 9A when the ultrasonic sensor 9A receives the search wave reflected by the object from the search wave transmitted from ultrasonic sensor 9A. In other words, a direct wave is a received wave when the ultrasonic sensor that transmitted the search wave and the ultrasonic sensor that received the search wave reflected by the object are the same. In contrast, among the received waves received by ultrasonic sensor 9A, the received wave resulting from the reflection of the search wave transmitted from an ultrasonic sensor other than ultrasonic sensor 9A (ultrasonic sensor 9B in this embodiment) by the object is referred to as an "indirect wave." The indirect wave is a wave received by ultrasonic sensor 9A when the ultrasonic sensor 9A receives a wave reflected by an object from an exploration wave transmitted from ultrasonic sensor 9B. In other words, the indirect wave is a wave received when the ultrasonic sensor that transmitted the exploration wave is different from the ultrasonic sensor that received the wave reflected by the object from the exploration wave.

[0034] Next, a method for determining the specific position (relative position with respect to the vehicle) of an object 15 present in front of the vehicle as shown in Figure 4 will be described, taking as an example a case where the position P (X, Y) of the object 15 is determined using a search wave transmitted from an ultrasonic sensor 9A. First, the ultrasonic sensor 9A transmits a direct wave and receives a wave reflected by the object 15, thereby measuring the distance Dr from the ultrasonic sensor 9A to the position P. Then, the ultrasonic sensor 9B receives a wave reflected by the object from the search wave transmitted from the ultrasonic sensor 9A as an indirect wave, thereby measuring the sum of the distance Dr from the ultrasonic sensor 9A to the position P and the distance Di from the ultrasonic sensor 9B to the position P. The distance Db between the ultrasonic sensors 9A and 9B is a fixed value for each vehicle and can be obtained by inputting it into the device in advance. As a result, the angles θ1 and θ2 between them can be calculated from the lengths of the three sides Dr, Di, and Db, and the specific position coordinates (X, Y (but relative position to the vehicle)) of the position P of the object 15 can also be determined using triangulation. Note that in the above example, the position P(X, Y) of the object 15 is determined using the search wave transmitted from the ultrasonic sensor 9A, but the position P(X, Y) of the object 15 can also be determined in the same way using the search wave transmitted from another ultrasonic sensor (for example, ultrasonic sensor 9B) located in a position where the search wave can reach the object 15.

[0035] However, detection of an object using triangulation using direct and indirect waves as shown in Figure 4 can only be performed in a portion of the detection range near the center of the vehicle within the detection range in which the ultrasonic sensors 9A to 9D can detect an object. That is, if there is a detection range 16 in which the ultrasonic sensors 9A to 9D can detect an object as shown in Figure 5, only ultrasonic sensor 9A can receive reflected waves from the area at the left end of the vehicle center, so the object can only be detected using direct waves. On the other hand, only ultrasonic sensor 9D can receive reflected waves from the area at the right end of the vehicle center, so the object can only be detected using direct waves. Hereinafter, the area in which the position of an object can be identified using triangulation using the detection distances of direct and indirect waves will be referred to as triangulation area 17, and the area in which the object must be detected using only the detection distance of direct waves will be referred to as direct wave area 18.

[0036] In the direct wave area 18, even if an object 15 is present to the left front of the vehicle as shown in FIG. 6 , the precise location of the object 15 (its relative position to the vehicle) cannot be determined. That is, the ultrasonic sensor 9A transmits a direct wave, which is a wave reflected by the object 15, and receives the direct wave to measure the distance Dr from the ultrasonic sensor 9A to position P. However, position P may be located anywhere on an arc of radius Dr centered on the ultrasonic sensor 9A. It is not guaranteed that an object is actually present in the direct wave area 18; for example, an object may be detected in the triangulation area 17. Therefore, only when triangulation using direct and indirect waves is not successful within the detection range of the ultrasonic sensor 9A's search waves, i.e., when triangulation is not successful and it is confirmed that no object exists in the triangulation area 17 within the detection range of the ultrasonic sensor 9A's search waves, and an object is detected using the direct wave, it can be assumed that the object is located in the direct wave area 18 at the left end, and therefore a warning about the object in the direct wave area 18 is issued. The same applies to the ultrasonic sensor 9D; only when triangulation using direct waves and indirect waves is not possible within the detection range of the ultrasonic sensor 9D's exploration waves, that is, when it is confirmed by triangulation failure that no object exists in the triangulation area 17 within the detection range of the ultrasonic sensor 9D's exploration waves, and when an object can be detected using direct waves, it can be assumed that the object is located in the direct wave area 18 on the right end, and therefore a warning is issued about the object in the direct wave area 18.

[0037] However, failure to perform triangulation does not only mean that direct or indirect waves cannot be received, but also includes cases where triangulation points cannot be calculated even when direct and indirect waves are received. Furthermore, in situations where detection by an ultrasonic sensor is difficult, such as when the object 15 has a curved surface, triangulation may not be performed even if the object is present in the triangulation area 17. Even in such cases, if direct waves are received and an alarm is issued for the presence of an object in the direct wave area 18, it is possible that an alarm will not be issued in the triangulation area 17 even though an object is actually present in the triangulation area 17, but will be issued in the direct wave area 18 where no object is present. To prevent this, the alarm may be limited in the direct wave area 18 even if an object is detected. Details will be described later.

[0038] Meanwhile, the driving assistance ECU 10 is an electronic control unit that performs various processes related to autonomous driving assistance. For example, it constantly detects the vehicle's current position, the lane the vehicle is traveling on, and the positions of surrounding obstacles, and controls the vehicle, including steering, drive source, and braking, so that the vehicle travels along the generated travel path at a speed according to the generated speed plan. In particular, when providing parking assistance, it identifies a parking space for the vehicle using the detection results of the front camera 6, rear camera 7, side cameras 8A and 8B, and ultrasonic sensors 9A to 9L, calculates a parking path to the identified parking space, and controls the vehicle to enter the parking space along the calculated parking path and complete parking. The LCD display 4 also displays the scenery (actual view) around the vehicle, and if there are objects around the vehicle that the user should pay attention to, such as other vehicles, a warning image indicating the presence of the object is superimposed on the scenery. The driving assistance ECU 10 is connected to the operation unit 3, LCD display 4, speaker 5, front camera 6, rear camera 7, side cameras 8A and 8B, and ultrasonic sensors 9A to 9L via an in-vehicle network such as a CAN. The driving assistance ECU 10 is also connected to various sensors mounted on the vehicle 2, such as a vehicle speed sensor, acceleration sensor, gyro sensor, steering sensor, and shift position sensor, as well as an in-vehicle device such as a navigation device. The detailed configuration of the driving assistance ECU 10 will be described later.

[0039] In addition, vehicle 2 has basic components as vehicle 2 in addition to the components shown in Figure 1, but we will only explain the configuration related to the control of automatic driving assistance and the control related to that configuration.

[0040] Next, a detailed description will be given of the driving assistance ECU 10 in particular of the driving assistance device 1 provided in the vehicle 2. Fig. 7 is a block diagram showing the configuration of the driving assistance device 1 according to this embodiment.

[0041] As shown in FIG. 4 , the driving assistance ECU (electronic control unit) 10 is an electronic control unit that controls the entire driving assistance device 1. It includes internal storage devices such as a CPU 31 as a calculation device and a control device, a RAM 32 that serves as a working memory for the CPU 31 to perform various calculation processes and stores driving trajectory data and other information used when the driving trajectory is calculated, a ROM 33 that stores control programs as well as a driving assistance processing program (see FIG. 8 ) described below, and a flash memory 34 that stores programs read from the ROM 33. The driving assistance ECU 10 also includes various processing algorithms. For example, the surrounding image display means displays a surrounding image showing the vehicle's surroundings on a display device. The object determination means divides the vehicle's surroundings into multiple areas for each direction centered on the vehicle's current position and determines whether an object is located in each of the multiple divided areas using the detection results of the ultrasonic sensors 9A to 9L. The warning image display means displays a warning image indicating the presence of an object in the surrounding image, targeting the area determined by the object determination means to contain an object.

[0042] The driving assistance ECU 10 is also connected to various sensors 36 for detecting vehicle behavior, such as a vehicle speed sensor, an acceleration sensor, a gyro sensor, a steering sensor, and a shift position sensor, as well as to each of the vehicle's drive units 37, such as the steering, brake, accelerator, and transmission, and detects the current vehicle behavior based on the detection results of these sensors 36, while controlling each of the drive units 37 to provide automatic driving assistance for the vehicle 2. Specific details of the automatic driving assistance include, for example, constantly detecting the current position of the vehicle, the lane the vehicle is traveling on, and the positions of surrounding obstacles, and controlling the vehicle, such as the steering, drive source, and brakes, so that the vehicle travels along the generated travel trajectory at a speed in accordance with the generated speed plan. However, it is also possible to automatically perform only the steering operation, and manually control the drive source and brakes.

[0043] The flash memory 34 also includes a vehicle information DB 35, which stores various information related to the vehicle 2. For example, the vehicle information DB 35 stores the installation positions (height from the ground and left-right position) and detection axes (optical axes for cameras), overall length, vehicle width, wheelbase, minimum turning radius, etc. of the cameras and ultrasonic sensors 9A to 9L installed on the vehicle 2. This information is input in advance by the occupants or a person from the vehicle manufacturer.

[0044] Next, a driving assistance processing program executed by the driving assistance ECU 10 in the driving assistance device 1 having the above configuration will be described with reference to FIG. 8. FIG. 8 is a flowchart of the driving assistance processing program according to this embodiment. Here, the driving assistance processing program is executed after the ACC (accessory power supply) of the vehicle 2 is turned on, and is a program that uses the ultrasonic sensors 9A to 9L to detect objects (e.g., people, bicycles, other vehicles, walls, etc.) around the vehicle 2 and issues a warning about the detected objects. The program shown in the flowchart in FIG. 8 below is stored in the RAM 32 and ROM 33 provided in the driving assistance device 1, and is executed by the CPU 31.

[0045] In this embodiment, warnings regarding objects are issued for each area defined around the vehicle. The areas are defined based on the sensors used to detect the areas. For example, FIG. 9 shows the division of areas ahead of the vehicle, which are designated from left to right as "FLL," "FLR," "FCLL," "FCLR," "FCRL," "FCRR," "FRL," and "FLL." Here, "FLL" and "FLR" are areas where objects are detected using search waves transmitted by ultrasonic sensor 9A. "FCLL" and "FCLR" are areas where objects are detected using search waves transmitted by ultrasonic sensor 9B. "FCRL" and "FCRR" are areas where objects are detected using search waves transmitted by ultrasonic sensor 9C. "FRL" and "FRR" are areas where objects are detected using search waves transmitted by ultrasonic sensor 9D.

[0046] Furthermore, "FLL" is an area where reflected waves cannot be received by sensors other than ultrasonic sensor 9A, i.e., ultrasonic sensor 9A detects objects using direct waves. "FLR" is an area where ultrasonic sensor 9A and ultrasonic sensor 9B can receive reflected waves, i.e., ultrasonic sensor 9A detects objects using triangulation with direct and indirect waves. "FCLL" is an area where ultrasonic sensor 9A and ultrasonic sensor 9B can receive reflected waves, i.e., ultrasonic sensor 9B detects objects using triangulation with direct and indirect waves. "FCLR" is an area where ultrasonic sensor 9B and ultrasonic sensor 9C can receive reflected waves, i.e., ultrasonic sensor 9B detects objects using triangulation with direct and indirect waves. "FCRL" is an area where ultrasonic sensor 9B and ultrasonic sensor 9C can receive reflected waves, i.e., ultrasonic sensor 9C detects objects using triangulation with direct and indirect waves. Furthermore, "FCRR" is the area where ultrasonic sensor 9C and ultrasonic sensor 9D can receive reflected waves, i.e., the area where ultrasonic sensor 9C detects objects using triangulation with direct waves and indirect waves. Also, "FRL" is the area where ultrasonic sensor 9C and ultrasonic sensor 9D can receive reflected waves, i.e., the area where ultrasonic sensor 9D detects objects using triangulation with direct waves and indirect waves. Furthermore, "FRR" is the area where reflected waves cannot be received by sensors other than ultrasonic sensor 9D, i.e., the area where ultrasonic sensor 9D detects objects using direct waves.

[0047] Although not shown in the drawings, the areas on the sides and rear of the vehicle are similarly divided based on the sensors used for detection.

[0048] In the following S1 and subsequent steps, an example of issuing a warning about an object will be described, taking as examples "FLL" and "FLR," which are areas where an object is detected by the search wave transmitted by the ultrasonic sensor 9A.

[0049] First, in step (hereinafter abbreviated as S) 1, the CPU 31 determines whether triangulation is successful when the ultrasonic sensor 9A (first detection sensor) receives the reflected wave of the search wave it transmitted as a direct wave and the ultrasonic sensor 9B (second detection sensor) receives the reflected wave of the search wave transmitted from the ultrasonic sensor 9A as an indirect wave. As already explained with reference to FIG. 4 , the detection of an object using triangulation is performed using the distance Dr from the ultrasonic sensor 9A to position P (first detection distance) calculated from the time between transmitting the search wave and receiving the direct wave, the sum of the distance Dr from the ultrasonic sensor 9A to position P and the distance Di from the ultrasonic sensor 9B to position P (second detection distance) detected from the time between transmitting the search wave and receiving the indirect wave, and the distance Db between the ultrasonic sensors 9A and 9B. Here, if either the direct wave or the indirect wave cannot be detected, the triangulation will not be successful, but even if both the direct wave and the indirect wave are detected, if the difference between the distance Dr and the distance Di is large as shown in Fig. 10, the triangulation points cannot be connected and the triangulation will not be successful. For example, when detecting the vicinity of a corner of the object or a surface in the depth direction, the above-mentioned difference in distance tends to occur particularly easily.

[0050] If ultrasonic sensor 9A receives the reflected wave of the search wave it transmitted as a direct wave, and ultrasonic sensor 9B receives the reflected wave of the search wave transmitted from ultrasonic sensor 9A as an indirect wave, and it is determined that triangulation is established between distances Dr and Di (S1: YES), the process proceeds to S2. On the other hand, if it is determined that at least one of the direct wave and the indirect wave was not received, or that it was received but triangulation was not established between distances Dr and Di (S1: NO), the process proceeds to S3.

[0051] In S2, the CPU 31 estimates that the object is located in "FLR" among the areas divided around the vehicle, and therefore displays a warning image on the liquid crystal display 4 to notify the user of the presence of the object in "FLR." Specifically, the warning image is displayed by superimposing it on the surrounding image of the vehicle that is displayed on the liquid crystal display 4. In addition to displaying the warning image, a warning sound may also be output.

[0052] The processing of S2 will be described below with a specific example. For example, Fig. 11 shows an example of a warning image 52 displayed when an overhead image 51 is displayed on the liquid crystal display 4 as an image of the surroundings of the vehicle. As shown in Fig. 11, the warning image 52 is displayed superimposed on the overhead image 51. The overhead image 51 also displays an image of the vehicle itself 53 indicating the position of the vehicle, and the positional relationship between the image of the vehicle itself 53 and the warning image 52 allows the user to grasp the position of an object 54 (a vehicle ahead in the example shown in Fig. 10). For example, in the example shown in FIG. 11 , it is determined that there are objects 54 in "FCLL", "FCLR", and "FCRL" in addition to "FLR" around the host vehicle, and a warning image 52 is displayed in the areas corresponding to "FLR", "FCLL", "FCLR", and "FCRL" in the overhead image 51. The shape of the warning image 52 can be set as appropriate, but for example, it may be in the shape of a partition that follows the position of the detected object 54 (the reflection point of the search wave) as shown in FIG. 11 . A user who views the overhead image 51 can understand that there is an object 54 ahead of the host vehicle.

[0053] Note that if the condition S1 is satisfied, i.e., if it is determined that the object is located in "FLR," the warning image 52 is not displayed in "FLL" even if direct waves are received. As mentioned above, "FLL" is an area where objects can be detected only using direct waves. However, detecting an object using direct waves can measure the distance to the object but cannot determine its specific location, making it impossible to determine whether the object is in "FLR" or "FLL." Therefore, to prevent erroneous guidance, if it is determined that the object is located in "FLR," the warning image 52 is not displayed in "FLL." As a result, as shown in FIG. 11 , a problem occurs in which the warning image 52 is not displayed in "FLL" where the object 54 is located. However, this is not a major problem because the warning image 52 is displayed in the adjacent "FLR."

[0054] The method for generating the overhead image 51 is well known and therefore not described in detail here, but the overhead image 51 is generated by performing viewpoint conversion and synthesis processing on the images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B. A warning image may be displayed on a bird's-eye view image viewed from diagonally below, rather than on the overhead image. Furthermore, the overhead and bird's-eye views are continuously displayed on the liquid crystal display 4 while the vehicle is traveling, regardless of whether a warning image is displayed or not.

[0055] On the other hand, in S3, the CPU 31 determines whether or not the ultrasonic sensor 9A has received, as a direct wave, a reflected wave of the search wave that it itself transmitted.

[0056] If it is determined that the ultrasonic sensor 9A has received the reflected wave of the search wave it transmitted as a direct wave (S3: YES), the process proceeds to S4. On the other hand, if it is determined that the direct wave was not received (S3: NO), it can be assumed that there is no object that should be warned in either "FLL" or "FLR", so the process ends without displaying a warning image (S6).

[0057] In S4, the CPU 31 determines whether the display restriction conditions for the warning image in "FLL" are satisfied. The display restriction conditions in S4 are conditions for preventing the warning image 52 from being disjointed, as shown in the left diagram of FIG. 12 , and are, for example, conditions that all of the following (Conditions 1) to (Conditions 4) are satisfied: (Condition 1) Triangulation (ultrasonic sensor 9A → ultrasonic sensor 9B) is not established; (Condition 2) Direct waves are detected; (Condition 3) Indirect waves (ultrasonic sensor 9A → ultrasonic sensor 9B) are detected; and (Condition 4) The detected distance is equal to or greater than a threshold value (20 cm). Regarding Condition 4, the CPU 31 basically determines whether the distance Dr (first detected distance) from the ultrasonic sensor 9A detected by the direct waves to position P is equal to or greater than a threshold value. However, it may also determine whether the distance Di (second detected distance) from the ultrasonic sensor 9B detected by the indirect waves to position P is equal to or greater than a threshold value. Alternatively, it may determine whether both are equal to or greater than a threshold value. In addition, when an object whose detection distance is less than the threshold is expected to be very close to the sensor, direct and indirect waves are more likely to echo from nearby locations, eliminating the difference in detection distance, so a distance condition is set.

[0058] When the display restriction condition for the warning image in "FLL" is satisfied, triangulation is not successful and the target cannot be detected by triangulation. However, since direct waves and reflected waves are received and the situation is not unusual in that the target is very close, it can be inferred that the target is present near "FLR." On the other hand, it can be inferred that the direct waves have likely detected an object in "FLR" rather than an object in "FLL." Therefore, when the display restriction condition in S4 is satisfied (S4: YES), the warning image is not displayed for "FLL" either (S6), as shown in the right diagram of FIG. 12 . This prevents the user from receiving unnatural guidance that would otherwise be missing information, and also prevents the user from mistaking the presence of a second target in "FLL."

[0059] Furthermore, if the warning image is not displayed even at "FLL" when the display restriction conditions are met, there is a possibility that no warning will be issued even if the object is located at "FLR" or "FLL." However, the display restriction conditions are basically met when the edge of the object is located near "FLR" as shown in FIG. 12, and since the warning image 52 is displayed at the adjacent "FCLL" or "FCLR," this is not a major problem.

[0060] On the other hand, if the display restriction condition of S4 is not satisfied (S4: NO), it can be estimated that no object exists in "FLR", which is the triangulation area 17, but since direct waves are received, it can be estimated that an object exists in "FLL", which is the direct wave area 18. Therefore, a warning image is displayed on the liquid crystal display 4 to notify the user of the presence of an object in "FLL" (S5). Specifically, a warning image 52 is displayed by superimposing it on the area corresponding to "FLL" in the surrounding image of the vehicle displayed on the liquid crystal display 4. In addition to displaying the warning image, a warning sound may also be output.

[0061] In the above explanation, an example of issuing a warning about an object was given using "FLL" and "FLR," which are areas where an object is detected by the search waves transmitted by ultrasonic sensor 9A, but the same processing is performed for "FRR" and "FRL," which are areas where an object is detected by the search waves transmitted by ultrasonic sensor 9D, except that the left and right sides are symmetrical. On the other hand, for "FCLL," "FCLR," "FCRL," and "FCRR," which are areas where an object is detected by the search waves transmitted by ultrasonic sensor 9B and ultrasonic sensor 9C, there are no areas that can be detected only by direct waves, so a processing is performed for each area in which a warning image 52 is displayed if triangulation is successful, and in which the warning image 52 is not displayed if triangulation is not successful.

[0062] As described above in detail, the driving assistance device 1 and the computer program executed by the driving assistance device 1 according to this embodiment include ultrasonic sensors 9A to 9D that are installed at different locations relative to the vehicle and positioned so that they can transmit search waves around the vehicle and receive waves including reflected waves from objects around the vehicle, and the surroundings of the vehicle are divided into a plurality of areas for each direction centered on the current position of the vehicle, and for each of the divided areas, the detection results of the ultrasonic sensors 9A to 9D are used to determine whether or not an object is located (S1, S3, S4), and the area where it is determined that an object is located is targeted for the area, and the surrounding image shows whether the object is located. The system includes a triangulation area 17 for determining the location of the object by triangulation using a first detection distance calculated by the ultrasonic sensor receiving its own search waves as direct waves and a second detection distance calculated by the ultrasonic sensor receiving search waves transmitted from other ultrasonic sensors as indirect waves, and a direct wave area 18 for determining the location of the object based only on the first detection distance, and the display of the warning image 52 in the direct wave area 18 is restricted under predetermined conditions (S4, S6). This prevents a warning about the object from being displayed in an unnatural or erroneous manner to the user. The condition for restricting the display of the warning image 52 in the direct wave area 18 is that triangulation between the first and second detection distances is not established, while direct and indirect waves are received. This prevents a situation in which a warning is not displayed in the triangulation area despite the presence of an object, but is displayed in the direct wave area where no object is present. Furthermore, the condition for restricting the display of the warning image 52 in the direct wave area 18 is that the first detection distance or the second detection distance is equal to or greater than a predetermined distance, so that it is possible to prevent the user from receiving an uncomfortable warning or a warning with incorrect content, except in special circumstances such as when the target object is located directly in front of the ultrasonic sensor.Furthermore, ultrasonic sensor 9A and ultrasonic sensor 9B are positioned on the same surface of the vehicle, with ultrasonic sensor 9A positioned further outward from the center of the vehicle than ultrasonic sensor 9B, and direct wave area 18 is positioned further outward from the center of the vehicle than triangulation area 17. Therefore, even if there is an area within the detection range in which ultrasonic sensors 9A to 9D can detect objects, where only ultrasonic sensor 9A or ultrasonic sensor 9D located at the edge can receive the reflected waves from an object in that area, it is possible to prevent the user from receiving an unnatural or erroneous warning.

[0063] The present invention is not limited to the above-described embodiment, and various improvements and modifications are possible without departing from the spirit and scope of the present invention. For example, in this embodiment, the warning about an object by the driving assistance processing program shown in FIG. 8 is always given while the vehicle is traveling, but it may be given only when the vehicle is traveling with automatic driving assistance. Alternatively, it may be given only when the vehicle is performing parking assistance, which is one type of automatic driving assistance.

[0064] In this embodiment, four ultrasonic sensors 9A to 9D for detecting objects are installed in front of the vehicle 2, but the number of ultrasonic sensors does not necessarily have to be four as long as there is a plurality of ultrasonic sensors, and may be, for example, two. The positions and shapes of the triangulation area 17 and the direct wave area 18 also differ depending on the number and arrangement of the ultrasonic sensors.

[0065] In this embodiment, as a surrounding image showing the surroundings of the vehicle, an overhead image generated from images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B is displayed on the liquid crystal display 4, and when a warning image 52 for an object is displayed, it is displayed superimposed on the overhead image (FIGS. 11 and 12). However, the surrounding image displayed on the liquid crystal display 4 may not be an image captured by a camera, but may be a schematic generated virtual landscape image (for example, a map image). Also, it is possible to display only the host vehicle image 53 and the warning image 52 without displaying the surrounding image.

[0066] In this embodiment, the driving assistance processing program (FIG. 8) is executed by the driving assistance ECU 10 of the driving assistance device 1, but the execution entity can be changed as appropriate. For example, the program may be executed by the control unit of the liquid crystal display 4, the vehicle control ECU, the control unit of the navigation device, or another in-vehicle device.

[0067] [Summary of this embodiment] This embodiment includes at least the following components: first detection sensors (9A to 9L) and second detection sensors (9A to 9L) that are installed at different locations relative to a vehicle (2) and are positioned so that they can transmit search waves around the vehicle and receive waves including waves reflected by objects around the vehicle; a surrounding image display means (10) that displays a surrounding image (51) showing the surroundings of the vehicle on a display device (4); an object determination means (10) that divides the surroundings of the vehicle into a plurality of areas for each direction around the current position of the vehicle and determines whether the object is located in each of the divided areas using the detection results of at least one of the first detection sensor and the second detection sensor; and a method of determining the location of the object (54) by the object determination means. and a warning image display means (10) for displaying a warning image (52) indicating that the object is located in the peripheral image for an area determined to be affected, wherein the divided areas include a triangulation area (17) for determining the position of the object by triangulation using a first detection distance calculated by the first detection sensor receiving the exploration wave transmitted by itself as a direct wave and a second detection distance calculated by the second detection sensor receiving the exploration wave transmitted from the first detection sensor as an indirect wave, and a direct wave area (18) for determining the position of the object only by the first detection distance, and the warning image display means limits the display of the warning image in the direct wave area under predetermined conditions.

[0068] According to this configuration, the display of the warning image in the direct wave area, which identifies the position of the target based on the detection distance detected by the direct wave under specified conditions, is restricted, so that when issuing a warning about the target, it is possible to prevent the user from receiving a warning that is unnatural or contains incorrect information.

[0069] In addition, in this embodiment, it is preferable that the specified condition be that the triangulation is not established between the first detection distance and the second detection distance, while the direct wave and the indirect wave are each received.

[0070] According to this configuration, it is possible to prevent a situation in which, even though an object exists in the triangulation area, a warning is not given in the triangulation area and a warning is given in the direct wave area where no object exists.

[0071] In this embodiment, it is preferable that the predetermined condition further includes the condition that the first detection distance or the second detection distance is equal to or greater than a predetermined distance.

[0072] With this configuration, it is possible to prevent the user from receiving an unnatural or erroneous warning, except in special circumstances such as when an object is located directly in front of the detection sensor.

[0073] In addition, in this embodiment, it is preferable that the first detection sensors (9A to 9L) and the second detection sensors (9A to 9L) are arranged on the same surface of the vehicle, and the first detection sensors are arranged further outward from the center of the vehicle than the second detection sensors, and the direct wave area (18) is located further outward from the center of the vehicle than the triangulation area (17).

[0074] With this configuration, even if there is an area within the detection range in which the detection sensor can detect an object where only the detection sensor located at the edge can receive the reflected waves from the object in that area, it is possible to prevent the user from receiving an uncomfortable warning or a warning with incorrect content.

[0075] 1... driving assistance device, 2... vehicle, 3... operation unit, 4... liquid crystal display, 9A to 9L... ultrasonic sensors (detection sensors), 10... driving assistance ECU, 15... object, 17... triangulation area, 18... direct wave area, 31... CPU, 51... bird's-eye view image (peripheral image), 52... warning image

Claims

1. A system comprising: a first detection sensor and a second detection sensor, each installed at a different location relative to a vehicle, positioned so that the first and second detection sensors can transmit search waves around the vehicle and receive waves including waves reflected by objects around the vehicle; a surrounding image display means for displaying a surrounding image showing the area around the vehicle on a display device; an object determination means for dividing the area around the vehicle into a plurality of areas for each direction around the current position of the vehicle, and for determining whether the object is located in each of the divided areas using the detection results of at least one of the first and second detection sensors; and a warning image display means for displaying a warning image indicating the location of the object in the surrounding image, for an area determined by the object determination means to be located in the area, wherein the divided areas include: triangulation areas in which the position of the object is identified by triangulation using a first detection distance calculated by the first detection sensor receiving the search waves transmitted by itself as direct waves, and a second detection distance calculated by the second detection sensor receiving the search waves transmitted from the first detection sensor as indirect waves. a direct wave area in which the position of the object is identified only by the first detection distance, wherein the warning image display means limits display of the warning image in the direct wave area under a predetermined condition.

2. A driving assistance device as described in claim 1, wherein the predetermined condition is that the triangulation is not established between the first detection distance and the second detection distance, while the direct wave and the indirect wave are each received.

3. The driving assistance device according to claim 2, wherein the predetermined condition further includes a condition that the first detection distance or the second detection distance is equal to or greater than a predetermined distance.

4. A driving assistance device as described in any one of claims 1 to 3, wherein the first detection sensor and the second detection sensor are arranged on the same surface of the vehicle, and the first detection sensor is arranged further outward from the center of the vehicle than the second detection sensor, and the direct wave area is located further outward from the center of the vehicle than the triangulation area.

Images