Driving assistance systems

Abstract

The present invention provides an operational support system that can quickly provide assistance to the target object while also reducing the processing load. [Solution] When the first detection distance, second detection distance, third detection distance, and fourth detection distance, which are distances measured by a first detection sensor and a second detection sensor that are in a positional relationship where they can mutually receive each other's received waves, satisfy predetermined conditions for detecting the same object, the position coordinates of the object are determined by triangulation using either a combination of the first detection distance and the second detection distance or a combination of the third detection distance and the fourth detection distance, and support is provided for the object based on the determined position coordinates of the object.

Description

Technical Field

[0001] The present invention relates to a driving assistance device that performs driving assistance for a vehicle. Background Art

[0002] Conventionally, as a safety device for ensuring safety during traveling or parking of a vehicle, a detection sensor for detecting surrounding objects (for example, people, bicycles, other vehicles, walls, etc.) such as an ultrasonic sensor, a millimeter wave radar sensor, and a LiDAR sensor is disposed on the vehicle, and a technique for warning a driver or performing automatic control of the vehicle based on a detection result of the detection sensor is known.

[0003] Such a detection sensor outputs a probe wave such as an ultrasonic wave, a millimeter wave, or an infrared ray, measures the time until the output probe wave is reflected by an object and returns, and detects the distance to the object. Further, if a plurality of detection sensors are disposed on the vehicle, it is possible to use indirect waves in addition to direct waves, and more accurate detection of the object is also enabled. The "direct wave" refers to a received wave in a case where the detection sensor that has transmitted the probe wave and the detection sensor that has received the reflected wave of the probe wave from the object as a received wave are the same. On the other hand, the "indirect wave" refers to a received wave in a case where the detection sensor that has transmitted the probe wave and the detection sensor that has received the reflected wave of the probe wave from the object as a received wave are different. For example, Japanese Patent Laid-Open No. 2016-81449 discloses a technique for disposing a plurality of detection sensors in a vehicle and detecting the position of an object by triangulation using a detection distance by a direct wave and a detection distance by an indirect wave. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Patent Laid-Open No. 2016-81449 (Paragraphs 0017-0021) Summary of Invention Problems to be Solved by the Invention

[0005] Here, if vehicle assistance were to be provided based on the detection results of the position of an object using triangulation as described in Patent Document 1 above, there was a problem that the processing load would be large. This problem will be explained using the example of a vehicle 101 equipped with multiple ultrasonic sensors S1 to S4, where the object to be detected is located in front of the vehicle, as shown in Figure 12. As shown in Figure 12, the detection of the object 102 by the vehicle 101 equipped with multiple ultrasonic sensors S1 to S4 is performed for each ultrasonic sensor. That is, the detection of the object 102 using ultrasonic sensor S1 as the source, the detection of the object 102 using ultrasonic sensor S2 as the source, the detection of the object 102 using ultrasonic sensor S3 as the source, and the detection of the object 102 using ultrasonic sensor S4 as the source are all performed in parallel and independently, and the existence of the object is confirmed by aligning the results of each detection, and the final vehicle assistance is provided. Examples 1 and 2 are given as requirements for implementing vehicle assistance for an object.

[0006] For example, in [Example 1], two adjacent ultrasonic sensors S1 and S2 act as the transmitter and indirect wave receiver, respectively, to detect the object 102. Specifically, ultrasonic sensor S1 acts as the transmitter, and the position coordinates (X1, Y1) of the object 102 are calculated by the above triangulation using direct and indirect waves. Ultrasonic sensor S2 acts as the transmitter, and the position coordinates (X2, Y2) of the object 102 are calculated by the above triangulation using direct and indirect waves. Subsequently, it is checked whether the calculated position coordinates (X1, Y1) and (X2, Y2) are consistent (whether it can be determined that the same object is being detected). If they are consistent, the presence of the object 102 at that location is confirmed, and support is provided for the object 102.

[0007] In contrast, in [Example 2], ultrasonic sensor S2 acts as the transmitter, and adjacent ultrasonic sensors S1 and S3 act as indirect wave receivers, respectively, to detect object 102. Specifically, ultrasonic sensor S2 acts as the transmitter and ultrasonic sensor S1 acts as the indirect wave receiver, and the position coordinates (X3, Y3) of object 102 are calculated by the above triangulation using direct and indirect waves. Then, ultrasonic sensor S2 acts as the transmitter and ultrasonic sensor S3 acts as the indirect wave receiver, and the position coordinates (X4, Y4) of object 102 are calculated by the above triangulation using direct and indirect waves. Subsequently, it is checked whether the calculated position coordinates (X3, Y3) and (X4, Y4) are consistent (whether it can be determined that the same object is being detected). If they are consistent, the presence of object 102 at that location is confirmed, and support is provided for object 102.

[0008] As a result, in both [Example 1] and [Example 2] above, determining the existence of a single object requires calculating its position coordinates using at least two triangulation operations, and coordinate consistency checks must also be performed. Furthermore, if there are multiple objects or if the size of the objects increases, the number of detectable sensors increases, requiring even more position coordinate calculation operations. This resulted in a problem of increased processing load.

[0009] The present invention was made to solve the aforementioned problems of the conventional method, and aims to provide an operation support device that can quickly provide support to an object and reduces the processing load. [Means for solving the problem]

[0010] To achieve the above objective, the first driving assistance device according to the present invention has a first detection sensor and a second detection sensor, each installed at different locations on the vehicle, which are in a positional relationship that allows them to transmit a search wave to the area around the vehicle and to mutually receive received waves including reflected waves that have been reflected by objects around the vehicle. The device obtains a first detection distance calculated by the first detection sensor receiving the reflected wave of the search wave transmitted by the first detection sensor as a direct wave, and a second detection distance calculated by the second detection sensor, which is different from the source, receiving the reflected wave of the search wave transmitted by the first detection sensor as an indirect wave, and the second detection sensor receives the reflected wave of the search wave transmitted by the second detection sensor as an indirect wave. The system obtains a third detection distance calculated by the second detection sensor, which is the source of the transmission, receiving the reflected wave of the exploration wave as a direct wave, and a fourth detection distance calculated by the first detection sensor, which is different from the source, receiving the reflected wave of the exploration wave transmitted by the second detection sensor as an indirect wave. If the first, second, third, and fourth detection distances satisfy predetermined conditions, the system identifies the position coordinates of the object by triangulation using either a combination of the first and second detection distances or a combination of the third and fourth detection distances, and provides support to the object based on the identified position coordinates of the object. Furthermore, "support for the target object" includes, for example, support related to guidance and warnings to help the user recognize the target object, and support related to vehicle control to prevent the vehicle from approaching the target object. In addition, for vehicles capable of autonomous driving assistance, steering control to avoid the target object may also be included.

[0011] Furthermore, the second driving assistance device according to the present invention comprises a first detection sensor and a second detection sensor, each installed at different locations on the vehicle, and positioned to transmit a search wave to the vicinity of the vehicle and to mutually receive received waves including reflected waves that have been reflected by objects around the vehicle; and a third detection sensor, installed in the opposite direction from the second detection sensor to the first detection sensor, which transmits a search wave to the vicinity of the vehicle and is positioned to mutually receive received waves including reflected waves that have been reflected by objects around the vehicle, at least with the first detection sensor, wherein the first detection sensor, which is the source of the transmission, directly receives the reflected wave of the search wave transmitted by the first detection sensor as a wave. The system obtains a calculated first detection distance, a second detection distance calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as an indirect wave by a second detection sensor different from the source, and a third detection distance calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as an indirect wave by a third detection sensor different from the source. If the first, second, and third detection distances satisfy predetermined conditions, the system identifies the position coordinates of the object by triangulation using either a combination of the first and second detection distances or a combination of the first and third detection distances, and provides support to the object based on the identified position coordinates of the object. [Effects of the Invention]

[0012] According to the first driving support device of the present invention having the above configuration, it is not necessary to perform both the identification of the object's position coordinates by triangulation with the first detection sensor as the source and the second detection sensor as the receiver, and the identification of the object's position coordinates by triangulation with the second detection sensor as the source and the first detection sensor as the receiver. Instead, support for the object can be provided by identifying only one of the position coordinates. As a result, support for the object can be provided quickly, and the processing load can be reduced.

[0013] Further, according to the second driving assistance device of the present invention, it is not necessary to perform both the identification of the position coordinates of the object by triangulation with the first detection sensor as the transmission source and the second detection sensor as the reception destination, and the identification of the position coordinates of the object by triangulation with the first detection sensor as the transmission source and the third detection sensor as the reception destination, and it becomes possible to perform assistance for the object only by identifying either one of the position coordinates. As a result, assistance for the object can be performed quickly, and the processing load can also be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] [Figure 1] It is a schematic configuration diagram of a vehicle according to the present embodiment. [Figure 2] It is a diagram showing an arrangement example of ultrasonic sensors on the front surface of the vehicle. [Figure 3] It is a diagram showing an arrangement example of ultrasonic sensors on the side surface of the vehicle. [Figure 4] It is a diagram illustrating a method for specifying the specific position of an object (relative position with respect to the vehicle) using triangulation. [Figure 5] It is a diagram illustrating a method for specifying the specific position of an object (relative position with respect to the vehicle) using triangulation. [Figure 6] It is a block diagram showing the configuration of the driving assistance device according to the present embodiment. [Figure 7] It is a flowchart of a driving assistance processing program according to the present embodiment. [Figure 8] It is a diagram illustrating the second same-object detection condition. [Figure 9] It is a diagram illustrating the second same-object detection condition. [Figure 10] It is a diagram illustrating the third same-object detection condition. [Figure 11] It is a diagram illustrating the same-object detection condition. [Figure 12] It is a diagram explaining the problems of the prior art. DETAILED DESCRIPTION OF EMBODIMENTS FOR CARRYING OUT THE INVENTION

[0015] Hereinafter, an embodiment embodying the driving support device according to the present invention will be described in detail with reference to the drawings. First, the vehicle 2 equipped with the driving support device 1 according to the present embodiment will be described below. Figure 1 is a schematic configuration diagram of the vehicle 2 according to the present embodiment.

[0016] Here, the vehicle 2 may be, for example, an automobile (internal combustion engine automobile) using an internal combustion engine (engine or the like) as a drive source, an automobile (electric automobile, fuel cell automobile or the like) using an electric motor (motor or the like) as a drive source, or an automobile (hybrid automobile) using both of them as drive sources. In addition, the vehicle type is not limited, and it may be a standard passenger car, or a commercial large truck, bus, construction machine or the like. Further, in the following description, a four-wheel automobile is assumed, but a two-wheel or three-wheel vehicle may also be used.

[0017] In addition, the vehicle 2 may be a vehicle capable of support travel by automated driving assistance in which the vehicle automatically travels regardless of the user's driving operation, in addition to manual driving travel that travels based on the user's driving operation. Alternatively, the vehicle may be a vehicle capable of executing only support travel by automated driving assistance. On the other hand, the vehicle 2 is not necessarily limited to a vehicle capable of support travel by the above automated driving assistance, and may be a vehicle capable of only travel by manual driving. However, regardless of whether the vehicle is a vehicle capable of executing only support travel by automated driving assistance or a vehicle capable of only travel by manual driving, when an object such as a pedestrian or a bicycle approaches the vehicle as described later, the vehicle is configured to be a vehicle capable of driving support such as alerting to those objects and deceleration control.

[0018] In addition, when the vehicle is a vehicle capable of support travel by automated driving assistance, the automated driving assistance may be performed only under specific situations such as during parking or leaving a parking space, may be performed for all road sections, or may be performed only while the vehicle is traveling on a specific road section (for example, an expressway provided with a gate (manned or unmanned, toll or free is not limited) at the boundary).

[0019] Furthermore, in vehicle control for autonomous driving assistance, for example, the vehicle's current position, the lane it is traveling in, and the position of surrounding obstacles are detected in real time, and vehicle control such as steering, drivetrain, and brakes is automatically performed so that the vehicle travels along a generated driving trajectory at a speed according to a similarly generated speed plan. In particular, when providing parking assistance, the system uses the detection results of sensors and cameras to confirm the parking space and its surroundings, calculates a parking trajectory to the parking space, and automatically performs vehicle control to enter the parking space along the calculated parking trajectory and complete the parking. However, it is also possible to automate only the steering operation, and to manually control the drivetrain and brakes. Alternatively, the system may only guide the vehicle to a parking space, and the user may manually perform the parking operation into the parking space.

[0020] As shown in Figure 1, the vehicle 2 includes an operating unit 3 that receives input from the occupant, a liquid crystal display 4 that displays bird's-eye view images, overhead view images, and other information related to driving assistance to the occupant, a speaker 5 that outputs voice guidance related to driving assistance, a front camera 6, a rear camera 7, and side cameras 8A and 8B for imaging the area around the vehicle, ultrasonic sensors 9A to 9L which are a type of detection sensor that detects obstacles around the vehicle, and a driving assistance ECU (Electronic Control Unit) 10 that performs various calculations based on the input information. The driving assistance device 1 includes the above-mentioned driving assistance ECU 10.

[0021] The following describes the various components of vehicle 2. First, the control unit 3 is located, for example, in front of the steering wheel and includes control buttons that are operated when starting the automated driving assistance system. By operating the control unit 3, the user can switch between manual driving, where the vehicle moves based on the user's driving input, and automated driving assistance, where the vehicle moves automatically without user input. The control unit 3 may also have a touch panel located in front of the liquid crystal display 4. It may also have a microphone and a voice recognition device.

[0022] The liquid crystal display 4 is a type of display device mounted on the instrument panel of the vehicle 2. It displays bird's-eye and overhead views of the area around the vehicle, generated by processing and combining images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B while the vehicle is in motion. In addition, if there are objects that the user should pay attention to, such as other vehicles or pedestrians, warning images indicating the presence of such objects may be displayed within the bird's-eye or overhead view. The liquid crystal display 4 may also be used for the navigation system.

[0023] Furthermore, speaker 5 is mounted on the instrument panel of vehicle 2 and outputs voice guidance and warning sounds related to driver assistance. In particular, when an object such as another vehicle or pedestrian approaches the vehicle, it outputs a warning sound for the object in a manner that indicates the direction of the object's location. Speaker 5 may also be used in conjunction with the navigation system.

[0024] Furthermore, the front camera 6 is an imaging device that has a camera using a solid-state image sensor such as a CCD, and is installed, for example, above the front bumper of the vehicle 2 or behind the rearview mirror, with the optical axis facing forward in the direction of travel of the vehicle.

[0025] The rear camera 7 is an imaging device that also has a camera using a solid-state image sensor such as a CCD, and is mounted, for example, near the center above the license plate attached to the rear of the vehicle 2, with the optical axis facing the rear of the vehicle.

[0026] Furthermore, the side cameras 8A and 8B are imaging devices that also have cameras using solid-state image sensors such as CCDs, and are mounted, for example, on the left and right side mirrors of vehicle 2, with the optical axis facing the side of the vehicle.

[0027] The driver assistance ECU 10 generates bird's-eye and overhead views of the vehicle's surroundings by performing viewpoint transformation and synthesis processing on the images captured by the front camera 6, rear camera 7, and side cameras 8A and 8B. Furthermore, during automated driving assistance, it performs image recognition processing on the captured images to detect lane markings, parking space markings, and obstacles (other vehicles, pedestrians, bicycles, walls, guardrails, and other structures) around the vehicle, and performs automated driving assistance based on the detection results. In particular, when performing parking assistance, it also uses the obstacle detection results from the cameras to check the parking space and its surroundings.

[0028] On the other hand, ultrasonic sensors 9A to 9L are arranged at predetermined intervals on the front, rear, and sides of the vehicle, respectively. They transmit ultrasonic waves as probe waves around the vehicle 2 and detect objects that reflected the probe waves by receiving reflected waves from objects around the vehicle. Specifically, they are a type of distance measuring sensor capable of detecting the distance (measured distance value) to the object that reflected the probe waves by measuring the time from transmission to reception. Furthermore, ultrasonic sensors 9A to 9L are configured to generate an output signal (including the distance to the detected object) corresponding to the reception result of the received wave and output it to the control unit. The objects to be detected by ultrasonic sensors 9A to 9L include, for example, people, bicycles, other vehicles, walls, and other obstacles that the vehicle 2 needs to avoid when driving, or obstacles that form a parking space. In addition, millimeter-wave sensors or radar sensors may be used as distance measuring sensors instead of ultrasonic sensors.

[0029] Furthermore, while the installation position and direction of each ultrasonic sensor 9A to 9L can be set as appropriate, in this embodiment, in order to make the detection range of the target object encompass all directions in front of, behind, and to the left and right of the vehicle's direction of travel, for example, ultrasonic sensors 9A to 9D are installed on the front of the vehicle 2 facing the direction of travel so that the direction of transmission of the probe wave is in front 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 direction of transmission of the probe 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 direction of transmission of the probe wave is to the right of the vehicle's direction of travel. Ultrasonic sensors 9I to 9L are installed on the rear of the vehicle 2 facing the opposite direction of travel so that the direction of transmission of the probe wave is to the rear of the vehicle. The height of each ultrasonic sensor 9A to 9L from the ground surface is approximately the same.

[0030] To explain using ultrasonic sensors 9A to 9D as an example, it is desirable that ultrasonic sensors 9A to 9D be installed at different positions on the front bumper or around the front grille above it on the front of vehicle 2, as shown in Figure 2, with even spacing between them without bias in the left-right direction, so that they can transmit detection waves to a wider area in front of the vehicle (i.e., to widen the range in which objects can be detected).

[0031] Specifically, as shown in Figure 2, ultrasonic sensor 9A is installed near the left front corner of vehicle 2, with the direction of transmission of the probe wave slightly tilted to the left of the direction of travel of vehicle 2, so as to transmit probe waves to the left front of vehicle 2. Ultrasonic sensor 9B is installed slightly to the left of the centerline of vehicle 2, with the direction of transmission of the probe wave facing the direction of travel of vehicle 2, so as to transmit probe waves mainly to the left front of vehicle 2. Ultrasonic sensor 9C is installed slightly to the right of the centerline of vehicle 2, with the direction of transmission of the probe wave facing the direction of travel of vehicle 2, so as to transmit probe waves mainly to the right front of vehicle 2. Ultrasonic sensor 9D is installed near the right front corner of vehicle 2, with the direction of transmission of the probe wave slightly tilted to the right of the direction of travel of vehicle 2, so as to transmit probe waves to the right front of vehicle 2. Furthermore, ultrasonic sensors 9A and 9D, and ultrasonic sensors 9B and 9C are each arranged symmetrically across the vehicle's centerline in a plan view. Although not shown in the diagram, the ultrasonic sensors 9I to 9L on the rear of vehicle 2 are also arranged similarly, symmetrically from top to bottom.

[0032] On the other hand, as shown in Figure 3, the lateral ultrasonic sensors 9E and 9F are installed to emit probe waves in a direction that intersects the direction of travel of the vehicle 2 at a 90-degree angle. Compared to the front and rear of the vehicle as described above, the number of sensors installed on the sides is smaller relative to the range, so there are areas where objects cannot be directly detected by ultrasonic sensors 9E and 9F. However, in these areas, it is possible to estimate the presence or position of objects from the object detection history of ultrasonic sensors 9A to 9L. Although not shown in the figure, ultrasonic sensors 9G and 9H on the right side of the vehicle 2 are installed symmetrically and similarly.

[0033] In this embodiment, among the ultrasonic sensors 9A to 9L, the ultrasonic sensors 9A to 9D on the front of the vehicle 2 and the ultrasonic sensors 9I to 9L on the rear of the vehicle 2 are installed in positions where they can receive reflected waves as indirect waves from adjacent sensors. By receiving both direct and indirect waves, it is possible to determine not only the distance to the object but also the specific position of the object (relative position to the vehicle) using triangulation. The ultrasonic sensors 9E to 9H on the sides are installed spaced apart from each other and cannot receive indirect waves, but as the vehicle moves, it is possible to determine the specific position of the object (relative position to the vehicle) using triangulation with respect to the distance measured at the previous position, the distance measured at the current position, and the distance traveled in between.

[0034] The following will provide a more detailed explanation, including the object detection method, using the ultrasonic sensors 9A to 9D, which are positioned on the front of vehicle 2, as an example. Here, among the ultrasonic sensors 9A to 9D, ultrasonic sensor 9A and ultrasonic sensor 9B are in a positional relationship that allows them to receive each other's signals. That is, ultrasonic sensor 9B is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9A as an indirect wave. Similarly, ultrasonic sensor 9A is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9B as an indirect wave. Furthermore, ultrasonic sensor 9B and ultrasonic sensor 9C are also in a positional relationship that allows them to receive each other's signals. That is, ultrasonic sensor 9C is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9B as an indirect wave. Similarly, ultrasonic sensor 9B is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9C as an indirect wave. Moreover, ultrasonic sensor 9C and ultrasonic sensor 9D are also in a positional relationship that allows them to receive each other's signals. That is, ultrasonic sensor 9D is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9C as an indirect wave. Similarly, ultrasonic sensor 9C is in a positional relationship that allows it to receive the probe wave transmitted by ultrasonic sensor 9D as an indirect wave.

[0035] On the other hand, for combinations of ultrasonic sensors other than those mentioned above, the received waves are basically in a positional relationship where they cannot be received by each other. For example, ultrasonic sensors 9C and 9D are in a positional relationship where they cannot receive the probe wave transmitted by ultrasonic sensor 9A as an indirect wave. Similarly, ultrasonic sensor 9D is in a positional relationship where it cannot receive the probe wave transmitted by ultrasonic sensor 9B as an indirect wave. Furthermore, ultrasonic sensor 9A is in a positional relationship where it cannot receive the probe wave transmitted by ultrasonic sensor 9C as an indirect wave. Also, ultrasonic sensors 9A and 9B are in a positional relationship where they cannot receive the probe wave transmitted by ultrasonic sensor 9D as an indirect wave.

[0036] Furthermore, the above-mentioned "receivable signal" means that the signal can be received to a degree that allows for effective detection of the distance to the target object. On the other hand, "unreceivable signal" includes not only the inability to receive any signal, but also reception of a signal strength that is too weak to effectively detect the distance to the target object.

[0037] In this embodiment, ultrasonic sensors 9A to 9D can determine not only the distance to an object but also the specific location of the object (relative position to the vehicle) by receiving direct and indirect waves as received waves. 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 caused by the reflection of the probe wave transmitted from ultrasonic sensor 9A by the object is called the "direct wave." The direct wave is the received wave when ultrasonic sensor 9A receives the reflection of the probe wave transmitted from ultrasonic sensor 9A by the object as the received wave. In other words, the direct wave is the received wave when the ultrasonic sensor that transmitted the probe wave and the ultrasonic sensor that received the reflection of the probe wave from the object as the received wave are the same. In contrast, among the received waves received by ultrasonic sensor 9A, the received wave caused by the reflection of the probe wave transmitted from an ultrasonic sensor other than ultrasonic sensor 9A (ultrasonic sensor 9B in this embodiment) by the object is called the "indirect wave." An indirect wave is the received wave when ultrasonic sensor 9A receives the reflected wave from the target object of the probe wave transmitted from ultrasonic sensor 9B. In other words, an indirect wave is the received wave when the ultrasonic sensor that transmitted the probe wave and the ultrasonic sensor that received the reflected wave from the target object of the probe wave are different.

[0038] Next, as shown in Figure 4, we will explain how to determine the specific position (relative position to the vehicle) of an object 15 when it is located in front of the vehicle, using the case where the position P(X,Y) of the object 15 is determined by a probe wave transmitted from the ultrasonic sensor 9A as an example. First, the distance Dr from ultrasonic sensor 9A to position P is measured by receiving the direct wave, which is the reflected wave that ultrasonic sensor 9A transmits and that is reflected by the object 15. In addition, ultrasonic sensor 9B receives the reflected wave, which is the probe wave transmitted from ultrasonic sensor 9A and reflected by the object, as an indirect wave, and the sum of the distance Dr from ultrasonic sensor 9A to position P and the distance Di from ultrasonic sensor 9B to position P is measured. Furthermore, the distance Db between ultrasonic sensor 9A and ultrasonic sensor 9B is a fixed value for each vehicle and can be obtained by inputting it into the device beforehand. As a result, the angles θ1 and θ2 between the three sides Dr, Di, and Db can be calculated from their lengths, and the specific position coordinates (X, Y (relative position to the vehicle)) of the object 15's position P can be determined using triangulation.

[0039] In the above example, the position P(X,Y) of the object 15 was described using a probe wave transmitted from ultrasonic sensor 9A. However, in this embodiment, since the vehicle 2 is equipped with multiple ultrasonic sensors, the position P(X,Y) of the object 15 can be similarly determined by probe waves transmitted from other ultrasonic sensors located within range of the object 15. For example, as shown in Figure 5, the distance Di from ultrasonic sensor 9B to position P, and the sum of the distance Di from ultrasonic sensor 9B to position P and the distance Dr from ultrasonic sensor 9A to position P can be measured using a probe wave transmitted from ultrasonic sensor 9B. Therefore, triangulation can be performed in a similar manner to determine the position P of the object 15. Furthermore, it is also possible to determine the position P of the object 15 by performing triangulation in a similar manner, using the same sensor as the source but changing the sensor receiving the indirect wave.

[0040] Here, object detection by ultrasonic sensors 9A to 9L is performed independently and in parallel for each sensor. For example, the measurement of distance Dr and Di using the probe wave transmitted from ultrasonic sensor 9A shown in Figure 4 and the measurement of distance Dr and Di using the probe wave transmitted from ultrasonic sensor 9B shown in Figure 5 are performed in parallel. Conventionally, the position P of object 15 was determined using the measurement results of all ultrasonic sensors capable of detecting the object. That is, triangulation was performed based on the measurement results of distance Dr and Di using the probe wave transmitted from ultrasonic sensor 9A to calculate the position P of object 15 (for example, let the calculated position coordinates be X1, Y1), while triangulation was also performed based on the measurement results of distance Dr and Di using the probe wave transmitted from ultrasonic sensor 9B to calculate the position P of object 15 (for example, let the calculated position coordinates be X2, Y2). Then, the system checked whether the calculated position coordinates (X1, Y1) and (X2, Y2) were consistent (i.e., whether it could be determined that the same object was being detected). If they were consistent, the presence of object 15 at that location was confirmed, and support was provided for object 15.

[0041] However, if such processing were to be performed, it would be necessary to calculate the position coordinates by triangulation at least twice in order to confirm the existence of a single object, and it would also be necessary to check for coordinate consistency. Therefore, there was a problem of increased processing load. In this embodiment, as will be described later, even if there are multiple measurement results of distance Dr and Di to an object from different sensors, instead of calculating the position coordinates from each measurement result, in situations where it can be estimated that the measurement results clearly detected the same object, triangulation is performed using only one measurement result to confirm the position of the object, and support is provided for that object. That is, the data to be used for triangulation is carefully selected before performing triangulation, and only the minimum necessary triangulation is performed. Details will be described later.

[0042] On the other hand, the driver assistance ECU 10 is an electronic control unit that performs various processes related to driver assistance. For example, if the object detection process using the ultrasonic sensors 9A to 9L determines that an object such as a pedestrian or bicycle is approaching the vehicle, it will issue a warning or perform deceleration control for that object. Furthermore, when performing automated driving assistance, it will calculate the driving trajectory and perform vehicle control to drive according to the calculated driving trajectory. The driver assistance ECU 10 is connected to the aforementioned operation unit 3, liquid crystal display 4, speaker 5, front camera 6, rear camera 7, side cameras 8A, 8B, and ultrasonic sensors 9A to 9L via an in-vehicle network such as CAN. It is also connected to various sensors mounted on the vehicle 2, such as GPS, vehicle speed sensor, acceleration sensor, gyro sensor, steering sensor, and shift position sensor, as well as in-vehicle devices such as the navigation system. The detailed configuration of the driver assistance ECU 10 will be described later.

[0043] In addition to the components shown in Figure 1, Vehicle 2 also has other basic components as Vehicle 2, but only the configuration related to object detection by ultrasonic sensors 9A to 9L and support for detected objects, as well as the control related to said configuration, will be explained.

[0044] Next, we will describe in detail the driver assistance ECU 10, which is part of the driver assistance system 1 provided by the vehicle 2 described above. Figure 6 is a block diagram showing the configuration of the driver assistance system 1 according to this embodiment.

[0045] As shown in Figure 6, the driver assistance ECU (Electronic Control Unit) 10 is an electronic control unit that controls the entire driver assistance system 1. It includes a CPU 31 as a calculation device and control device, a RAM 32 which is used as working memory when the CPU 31 performs various calculations and stores driving trajectory data when the driving trajectory is calculated, a ROM 33 which stores control programs as well as driver assistance processing programs (see Figure 7) described later, and a flash memory 34 which stores programs read from the ROM 33. The driver assistance ECU 10 executes various functions as a processing algorithm.For example, a function to obtain a first detection distance calculated by the first ultrasonic sensor receiving the reflected wave of the probe wave transmitted by the first ultrasonic sensor as a direct wave, and a second detection distance calculated by the second ultrasonic sensor, which is different from the source, receiving the reflected wave of the probe wave transmitted by the first ultrasonic sensor as an indirect wave; a function to obtain a third detection distance calculated by the second ultrasonic sensor, which is the source, receiving the reflected wave of the probe wave transmitted by the second ultrasonic sensor as a direct wave, and a fourth detection distance calculated by the first ultrasonic sensor, which is different from the source, receiving the reflected wave of the probe wave transmitted by the second ultrasonic sensor as an indirect wave; and when the first, second, third, and fourth detection distances satisfy predetermined conditions, a triangulation using either a combination of the first and second detection distances or a combination of the third and fourth detection distances. The system includes functions for determining the position coordinates of an object through surveying, providing support to the object based on the determined position coordinates, obtaining a first detection distance calculated by the first ultrasonic sensor receiving the reflected wave of the probe wave transmitted by the first ultrasonic sensor as a direct wave, a second detection distance calculated by the second ultrasonic sensor receiving the reflected wave of the probe wave transmitted by the first ultrasonic sensor as an indirect wave, and a third detection distance calculated by the third ultrasonic sensor receiving the reflected wave of the probe wave transmitted by the first ultrasonic sensor as an indirect wave, and a function for determining the position coordinates of an object by triangulation using either a combination of the first and second detection distances or a combination of the first and third detection distances when the first, second, and third detection distances satisfy predetermined conditions.

[0046] Furthermore, the driver assistance ECU 10 is connected to various sensors 36 for detecting the vehicle's current position and behavior, such as GPS, vehicle speed sensor, wheel speed sensor, acceleration sensor, gyro sensor, steering sensor, and shift position sensor, as well as to various drive units 37 of the vehicle, such as steering, brakes, accelerator, and transmission. For example, when performing automated driving assistance, the ECU 10 detects the vehicle's current behavior based on the detection results of these sensors 36 and controls each drive unit 37 to perform automated driving assistance for the vehicle 2. Specifically, the automated driving assistance may include, for example, detecting the vehicle's current position, the lane it is traveling in, and the position of surrounding obstacles, and controlling the vehicle, such as the steering, drive source, and brakes, so that it travels along the generated driving trajectory at a speed according to the generated speed plan. However, it is also possible to perform only the steering operation automatically, and control of the drive source and brakes based on manual operation.

[0047] Furthermore, ROM33 includes vehicle information DB35, which stores various information about vehicle 2. For example, it stores the installation positions (height from the ground, left-right position) and detection axes (optical axis and field of view for cameras) of cameras and ultrasonic sensors 9A-9L installed on vehicle 2, as well as the overall length, vehicle width, wheelbase, and minimum turning radius. This information is entered in advance by the occupants or personnel from the vehicle manufacturer.

[0048] Next, the driver assistance processing program executed by the driver assistance ECU 10 in the driver assistance device 1 having the above configuration will be explained with reference to Figure 7. Figure 7 is a flowchart of the driver assistance processing program according to this embodiment. Here, the driver assistance processing program is executed after the ACC power supply (accessory power supply) of the vehicle 2 is turned ON, and it is a program that uses ultrasonic sensors 9A to 9L to detect objects (e.g., people, bicycles, other vehicles, walls, etc.) around the vehicle 2, and provides driver assistance for the detected objects. The program shown in the flowchart in Figure 7 below is stored in the RAM 32 and ROM 33 of the driver assistance device 1 and is executed by the CPU 31.

[0049] As shown in Figure 1, vehicle 2 is equipped with ultrasonic sensors 9A to 9D that have a detection range in front of vehicle 2, ultrasonic sensors 9E to 9H that have a detection range to the sides of vehicle 2, and ultrasonic sensors 9I to 9L that have a detection range behind vehicle 2. Below, we will explain the detection of objects using ultrasonic sensors 9A to 9D and ultrasonic sensors 9I to 9L, which are positioned in a way that allows them to receive each other's signals.

[0050] First, in step 1 (hereinafter abbreviated as S), the CPU 31 acquires the measured (distance-measuring) distance measured by the ultrasonic sensors 9A to 9D installed in the vehicle 2. The detection of objects using ultrasonic sensors has already been explained using Figures 4 and 5, but for example, in a combination where ultrasonic sensor 9A is the source and ultrasonic sensor 9B is the receiver of the indirect wave, the distance Dr from ultrasonic sensor 9A to position P, calculated from the time from the transmission of the probe wave to the reception of the direct wave, and the sum of the distance Dr from ultrasonic sensor 9A to position P and the distance Di from ultrasonic sensor 9B to position P, detected from the time from the transmission of the probe wave to the reception of the indirect wave, are acquired as the measured distances. Similarly, the measured distance for combinations where ultrasonic sensor 9B is the source and ultrasonic sensor 9A is the receiver of the indirect wave, the measured distance for combinations where ultrasonic sensor 9B is the source and ultrasonic sensor 9C is the receiver of the indirect wave, the measured distance for combinations where ultrasonic sensor 9C is the source and ultrasonic sensor 9B is the receiver of the indirect wave, the measured distance for combinations where ultrasonic sensor 9C is the source and ultrasonic sensor 9D is the receiver of the indirect wave, and the measured distance for combinations where ultrasonic sensor 9D is the source and ultrasonic sensor 9C is the receiver of the indirect wave. Furthermore, the measured distance measured by ultrasonic sensors 9I to 9L equipped on vehicle 2 is also obtained in the same manner. However, the measured distance cannot be obtained for combinations of ultrasonic sensors that cannot receive at least one of the direct wave and the indirect wave.

[0051] Furthermore, in step S1, the CPU 31 acquires the measurement distance measured based on the first wave of probe transmitted by the ultrasonic sensors 9A-9D and 9I-9L, and the measurement distance measured based on the second wave of probe transmitted by the ultrasonic sensors 9A-9D and 9I-9L, respectively.

[0052] Next, in S2, the CPU31 decides whether to use the measurement distance measured based on the first wave of exploration or the measurement distance measured based on the second wave of exploration to perform the following processing from S3 onward.

[0053] To explain the decision method for S2, it is basically decided to use the measurement distance measured based on the first wave of exploration to perform the following S3 and subsequent processes. However, if a continuous value of the measurement distance cannot be obtained, specifically if the measurement distance suddenly becomes shorter in the second wave compared to the first wave, there is no guarantee that the correct measurement distance was measured in the first wave. Therefore, it is decided to use the measurement distance measured based on the second wave of exploration, which is a more urgent measurement result (a measurement result indicating that the target object is in a closer position), to perform the following S3 and subsequent processes.

[0054] Subsequently, the following processes S3 to S7 are performed on pairs of adjacent ultrasonic sensors. A pair of adjacent ultrasonic sensors refers to a pair of ultrasonic sensors that are positioned in a mutually receivable location, specifically: (a) ultrasonic sensor 9A and ultrasonic sensor 9B, (b) ultrasonic sensor 9B and ultrasonic sensor 9C, (c) ultrasonic sensor 9C and ultrasonic sensor 9D, (d) ultrasonic sensor 9I and ultrasonic sensor 9J, (e) ultrasonic sensor 9J and ultrasonic sensor 9K, and (f) ultrasonic sensor 9K and ultrasonic sensor 9L. The measurement distance obtained in S1 for the above combinations (a) to (f) includes two measurement distances, each with the source and destination reversed. For example, if the measurement distance obtained for "(a) combination of ultrasonic sensor 9A and ultrasonic sensor 9B" is to include the measurement distance for a combination where ultrasonic sensor 9A is the source and ultrasonic sensor 9B is the recipient of the indirect wave, and conversely, the measurement distance for a combination where ultrasonic sensor 9B is the source and ultrasonic sensor 9A is the recipient of the indirect wave. However, ultrasonic sensor combinations for which a measurement distance could not be obtained are excluded from processing.

[0055] First, in S3, the CPU 31 uses the measurement distance obtained in S1 to determine whether the combination of ultrasonic sensors to be processed satisfies the first identical object detection condition. Here, the first identical object detection condition is one of the conditions for considering that two adjacent ultrasonic sensors are each detecting the same identical object.

[0056] In the following explanation, we will use the combination of ultrasonic sensor 9A and ultrasonic sensor 9B (a) as an example, but the same processing will be performed for combinations (b) to (f). Furthermore, in the following explanation, for the combination of ultrasonic sensor 9A and ultrasonic sensor 9B (a), the measurement distance obtained in S1 will be referred to as the first detection distance d1, the measurement distance calculated when the source ultrasonic sensor 9A receives the reflected wave of the probe wave transmitted by ultrasonic sensor 9A (first detection sensor) as a direct wave, the measurement distance calculated when the source ultrasonic sensor 9B receives the reflected wave of the probe wave transmitted by ultrasonic sensor 9A as an indirect wave, the measurement distance l1, the measurement distance calculated when the source ultrasonic sensor 9B receives the reflected wave of the probe wave transmitted by ultrasonic sensor 9B as a direct wave, and the measurement distance calculated when the source ultrasonic sensor 9A receives the reflected wave of the probe wave transmitted by ultrasonic sensor 9B as an indirect wave, and the measurement distance l2.

[0057] The first condition for detecting identical objects is that the following equation (1) is satisfied. |l1-l2| ≤ threshold····(1) Here, the threshold is a value that is sufficiently small compared to the detection distance, and the fact that the difference between the second detection distance l1 and the fourth detection distance l2 is within the threshold means, in other words, that the second detection distance l1 and the fourth detection distance l2 are close enough to be considered the same distance. The threshold should be set taking into account the detection error, for example, to 10 cm.

[0058] Next, in S4, the CPU 31 uses the measurement distance obtained in S1 to determine whether the combination of ultrasonic sensors to be processed satisfies the second identical object detection condition. Here, the second identical object detection condition is one of the conditions for considering that two adjacent ultrasonic sensors are each detecting the same identical object.

[0059] The second condition for detecting identical objects is that both equations (2) and (3) below are satisfied. (Mean of l1 and l2) - (d1 + d2) ≥ 0 ····(2) (Mean of l1 and l2)^2 - (d1 + d2)^2 ≤ D^2 ····(3) (*D is the distance between ultrasonic sensor 9A and ultrasonic sensor 9B) Specifically, the condition is that the difference between the average value of the second detection distance l1 and the fourth detection distance l2 and the sum of the first detection distance d1 and the third detection distance d2 is 0 or greater, and the difference between the square of the average value of the second detection distance l1 and the fourth detection distance l2 and the square of the sum of the first detection distance d1 and the third detection distance d2 is less than or equal to the square of the inter-sensor distance, which is the distance between ultrasonic sensor 9A and ultrasonic sensor 9B.

[0060] Here, equation (2) assumes that the object 15 detected by ultrasonic sensors 9A and 9B is a narrow object 15 such as a pole, as shown in Figure 8. When such a narrow object 15 exists, the measured distance when the same object 15 is measured by ultrasonic sensors 9A and 9B respectively will satisfy the condition in (1) above.

[0061] On the other hand, equation (3) assumes, for example, that the object 15 detected by ultrasonic sensors 9A and 9B is a large, wide object 15 such as a vehicle or a wall, as shown in Figure 9. When such a large object 15 exists, the measured distance when the same object 15 is measured by ultrasonic sensors 9A and 9B respectively will satisfy the conditions of (2) above.

[0062] Next, in S5, the CPU 31 uses the measurement distance obtained in S1 to determine whether the combination of ultrasonic sensors to be processed satisfies the third identical object detection condition. Here, the third identical object detection condition is one of the conditions for considering that two adjacent ultrasonic sensors are each detecting the same identical object.

[0063] The third condition for detecting identical objects is that all of the following equations (4) to (7) are satisfied. (l1-d1)^2≦d1^2+D^2····(4) d1^2≦(l1-d1)^2+D^2···(5) (l2-d2)^2≦d2^2+D^2····(6) d2^2≦(l2-d2)^2+D^2···(7) (*D is the distance between ultrasonic sensor 9A and ultrasonic sensor 9B) That is, the conditions are that the square of the difference between the second detection distance l1 and the first detection distance d1 is less than or equal to the sum of the square of the first detection distance d1 and the square of the distance between sensors D, and the square of the first detection distance d1 is less than or equal to the sum of the square of the difference between the second detection distance l1 and the first detection distance d1 and the square of the distance between sensors D, and the square of the difference between the fourth detection distance l2 and the third detection distance d2 is less than or equal to the sum of the square of the third detection distance d2 and the square of the distance between sensors D, and the square of the third detection distance d2 is less than or equal to the sum of the square of the difference between the fourth detection distance l2 and the third detection distance d2 and the square of the distance between sensors D.

[0064] Here, equations (4) to (7) are conditions that indicate, for example, that the object 15 detected by ultrasonic sensors 9A and 9B is located in the area between the detection axes of ultrasonic sensors 9A and 9B (hereinafter referred to as the central area), as shown in Figure 10. The reason why the location of the detected object within the central area is considered one of the conditions for detecting the same object is to exclude the ghost detection state, where, for example, the direct wave and indirect wave detect different objects, resulting in the calculation that the object is located in a different position than its actual location. In the ghost detection state, even if the first and second identical object detection conditions mentioned above are met, it is possible that the two adjacent ultrasonic sensors are actually detecting different objects.

[0065] Furthermore, by setting a third identical object detection condition, the system will not detect the location of an object if it is located outside the central area (and therefore will not be able to provide assistance to the object). However, since the processing in S3 to S7 is performed on all combinations of two adjacent ultrasonic sensors, even if the location of the object cannot be detected with one combination, assistance is still possible if the location of the object can be detected with another combination, and the above problem will not occur.

[0066] Furthermore, as a third condition for detecting the same object, the following conditions (8) to (12) may be set as OR conditions. When the conditions of equations (8) to (12) are met, it can be considered that two adjacent ultrasonic sensors have detected the same object located to the right outside the central area, rather than in a ghost detection state. (l1-d1)^2≦d1^2+D^2····(8) d1^2>(l1-d1)^2+D^2····(9) (l2-d2)^2>d2^2+D^2····(10) d2^2≦(l2-d2)^2+D^2···(11) Other ultrasonic sensors adjacent to the left did not detect anything... (12) (*D is the distance between ultrasonic sensor 9A and ultrasonic sensor 9B)

[0067] Furthermore, as a third condition for detecting the same object, the following conditions (13) to (17) may be set as OR conditions. When the conditions (13) to (17) are met, it can be considered that the same object located to the left outside the central area is being detected by two adjacent ultrasonic sensors, rather than being in a ghost detection state. (l1-d1)^2>d1^2+D^2····(13) d1^2≦(l1-d1)^2+D^2···(14) (l2-d2)^2≦d2^2+D^2····(15) d2^2>(l2-d2)^2+D^2····(16) Other ultrasonic sensors adjacent to the right did not detect anything... (17) (*D is the distance between ultrasonic sensor 9A and ultrasonic sensor 9B)

[0068] Subsequently, in S6, the CPU 31 determines whether all of the conditions in S3 to S5 are met for the combination of ultrasonic sensors to be processed.

[0069] Then, if it is determined that all of the conditions in S3 to S5 are met for the combination of ultrasonic sensors to be processed (S6: YES), it is assumed that the two adjacent ultrasonic sensors are each detecting the same object. For example, if it is determined that all of the conditions in S3 to S5 are met for "(a) combination of ultrasonic sensor 9A and ultrasonic sensor 9B", the object detected by ultrasonic sensor 9A and the object detected by ultrasonic sensor 9B are assumed to be the same object.

[0070] Therefore, in S7, the CPU 31 calculates the position coordinates of the object by triangulation using the measurement distance that is most reliable for identifying the position coordinates of the object from among the measurement distances acquired in S1 for the combination of ultrasonic sensors to be processed. For example, if the measurement distances acquired for "(a) combination of ultrasonic sensor 9A and ultrasonic sensor 9B" are those obtained in S1, the measurement distances for the combination in which ultrasonic sensor 9A is the transmitter and ultrasonic sensor 9B is the indirect wave receiver (first detection distance d1 and second detection distance l1), and the measurement distances for the combination in which ultrasonic sensor 9B is the transmitter and ultrasonic sensor 9A is the indirect wave receiver (third detection distance d2 and fourth detection distance l2) are obtained. The CPU 31 then calculates the position coordinates of the object by triangulation using the measurement distance that is more reliable for identifying the position coordinates of the object from among these measurement distances. This makes it possible to select the data to be used for triangulation before performing triangulation and to calculate the position coordinates of the object with a high degree of reliability using only the minimum necessary triangulation.

[0071] Furthermore, the following methods are examples of the most reliable methods for determining the measurement distance to identify the position coordinates of an object. (A) If the object is on the right side, the measured distance measured using the ultrasonic sensor on the left side as the source is considered to have high reliability, and if the object is on the left side, the measured distance measured using the ultrasonic sensor on the right side as the source is considered to have high reliability. (B) The measurement distance obtained by an ultrasonic sensor that can continuously acquire measurement distance without becoming unable to measure is considered to have higher reliability. (C) The shorter measurement distance is considered to have higher reliability.

[0072] As explained using Figures 4 and 5, the detection of an object using triangulation is performed by calculating the angles θ1 and θ2 between the three sides Dr, Di, and Db, which are identified by the measured distance. Then, the specific position coordinates (X, Y (relative position to the vehicle)) of the object 15's position P are calculated using these angles. Here, if either direct or indirect waves cannot be detected, the triangulation is invalid. However, even if both direct and indirect waves are detected, if the difference between distance Dr and distance Di is large, the triangulation points cannot be connected and the triangulation may be invalid.

[0073] On the other hand, if it is determined that the combination of ultrasonic sensors to be processed does not satisfy any of the conditions S3 to S5 (S6: NO), it is unclear whether the two adjacent ultrasonic sensors are detecting the same object, and the position of the object cannot be determined. Therefore, the process ends without calculating the specific position coordinates of the object.

[0074] The processes S3 to S7 described above are performed on combinations (b) to (f), and if the conditions of S3 to S5 are met for each combination, the position coordinates (up to 6 coordinates) of the detected object will be calculated.

[0075] Next, the following processes S8 to S11 are performed on combinations of three adjacent ultrasonic sensors. A combination of three adjacent ultrasonic sensors is a combination of two ultrasonic sensors that are positioned to mutually receive each other's received waves, plus a third ultrasonic sensor that is positioned to mutually receive each other's received waves. Specifically, these are: (g) the combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C; (h) the combination of ultrasonic sensor 9B, ultrasonic sensor 9C, and ultrasonic sensor 9D; (i) the combination of ultrasonic sensor 9I, ultrasonic sensor 9J, and ultrasonic sensor 9K; and (j) the combination of ultrasonic sensor 9J, ultrasonic sensor 9K, and ultrasonic sensor 9L. For combinations (g) to (j) above, the measurement distance acquired in S1 includes two measurement distances, each with the same transmitter but with the indirect wave receiving destinations swapped. For example, if the measurement distance is obtained for "(g) a combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C," it includes the measurement distance for a combination where ultrasonic sensor 9B is the source and ultrasonic sensor 9A is the recipient of the indirect wave, and conversely, the measurement distance for a combination where ultrasonic sensor 9B is the source and ultrasonic sensor 9C is the recipient of the indirect wave. However, ultrasonic sensor combinations for which measurement distance could not be obtained are excluded from processing.

[0076] First, in S8, the CPU 31 uses the measurement distance obtained in S1 to determine whether the combination of ultrasonic sensors to be processed satisfies the same object detection condition. Here, the same object detection condition is the condition for which three adjacent ultrasonic sensors are considered to be detecting the same object.

[0077] In the following explanation, we will use the processing for “(g) combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C” as an example, but the same processing will be performed for combinations (h) to (j). Furthermore, in the following explanation, for the “(g) combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C” obtained in S1, the measurement distance calculated by the ultrasonic sensor 9B that transmits the probe wave received as a direct wave by the source ultrasonic sensor 9B will be called the first detection distance d1, the measurement distance calculated by the ultrasonic sensor 9A (second detection sensor) that is different from the source that receives the probe wave transmitted by ultrasonic sensor 9B as an indirect wave will be called the second detection distance l1, and the measurement distance calculated by the ultrasonic sensor 9C (third detection sensor) that is installed in the opposite direction from ultrasonic sensor 9A that receives the probe wave transmitted by ultrasonic sensor 9B as an indirect wave will be called the third detection distance l2.

[0078] The conditions for detecting identical objects are that the following equation (18) is satisfied. α + β + γ = 360 degrees... (18) Here, as shown in Figure 11, the angle between the first side connecting the installation position of ultrasonic sensor 9B to the installation position of ultrasonic sensor 9A and the second side connecting the position of ultrasonic sensor 9B to the position of object 15 is defined as α (first angle). Furthermore, the angle between the third side connecting the installation position of ultrasonic sensor 9B to the installation position of ultrasonic sensor 9C and the aforementioned second side is defined as β (second angle). In addition, the angle between the first side and the third side is defined as γ (third angle).

[0079] Furthermore, α can be calculated based on the first detection distance d1, the second detection distance l1, and the distance between ultrasonic sensors 9A and 9B. The distance between ultrasonic sensors 9A and 9B is assumed to be stored in the vehicle information DB35 beforehand. Similarly, β can be calculated based on the first detection distance d1, the third detection distance l2, and the distance between ultrasonic sensors 9B and 9C. The distance between ultrasonic sensors 9B and 9C is assumed to be stored in the vehicle information DB35 beforehand. Moreover, γ can be calculated based on the distances between ultrasonic sensors 9A, 9B, and 9C.

[0080] Furthermore, regarding equation (18) above, it is not necessary to require that the sum of α, β, and γ be exactly 360 degrees. Rather, it is preferable to consider measurement errors and other factors and assume that the equation holds true if it is within, for example, ±10 degrees. Also, by setting the conditions for equation (18) above, it is possible to exclude ghost detection states where, for example, a direct wave and an indirect wave detect different objects, causing the calculated object to be located at a different position than its actual location.

[0081] Subsequently, in S9, the CPU 31 determines whether the combination of ultrasonic sensors to be processed satisfies the conditions of S8.

[0082] Then, if it is determined that the conditions of S8 are met for the combination of ultrasonic sensors to be processed (S9: YES), the three adjacent ultrasonic sensors are considered to be detecting the same object. For example, if it is determined that the conditions of S8 are met for "(a) combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C", the object detected with ultrasonic sensor 9B as the source and ultrasonic sensor 9A as the indirect wave receiver is considered to be the same object as the object detected with ultrasonic sensor 9B as the source and ultrasonic sensor 9C as the indirect wave receiver.

[0083] Therefore, in S10, the CPU 31 calculates the position coordinates of the object by triangulation using the measurement distance that is most reliable for identifying the position coordinates of the object among the measurement distances acquired in S1 for the combination of ultrasonic sensors to be processed. For example, if the measurement distances to be acquired for "(a) combination of ultrasonic sensor 9A, ultrasonic sensor 9B, and ultrasonic sensor 9C" are to be Further details are the same as those described in S7 above, so the explanation will be omitted.

[0084] On the other hand, if it is determined that the combination of ultrasonic sensors to be processed does not satisfy the conditions of S8 (S9: NO), it is unclear whether the three adjacent ultrasonic sensors are detecting the same object, and the position of the object cannot be determined. Therefore, the process ends without calculating the specific position coordinates of the object.

[0085] The processes S8 to S10 described above are performed on combinations (g) to (j), and if the conditions of S8 are met for each combination, the position coordinates (up to 4 coordinates) of the detected object will be calculated.

[0086] Subsequently, in S11, the CPU 31 provides support to the object based on the most urgent position coordinate among the position coordinates of the object calculated in S7 and S10. The most urgent position coordinate is, for example, the position coordinate that is in the direction of the vehicle's movement (forward if the vehicle is moving forward, backward if it is moving backward) and is closest to the vehicle.

[0087] Furthermore, support for the target object includes, for example, support related to guidance and warnings to make the user aware of the target object, and support related to vehicle control to prevent the vehicle from approaching the target object. Specifically, a warning image is displayed on the LCD display 4 at the location coordinates of the target object that is judged to be of the highest urgency, relative to the overhead or bird's-eye view image showing the area around the vehicle. Alternatively, a warning sound is output from the speaker 5 to notify the target object. Alternatively, a control signal is sent to the drive unit 37 to perform deceleration control or stopping control to prevent approach to the location coordinates of the target object that is judged to be of the highest urgency. In addition, if the vehicle 2 is driving with automated driving assistance, steering control may be performed to avoid the target object.

[0088] As described in detail above, according to the driving support device 1 and the computer program executed by the driving support device 1 according to this embodiment, a first detection sensor (e.g., ultrasonic sensor 9A) and a second detection sensor (e.g., ultrasonic sensor 9B) are installed at different locations relative to the vehicle 2, and are in a positional relationship that allows them to transmit probe waves to the area around the vehicle 2 and to mutually receive received waves including reflected waves that have been reflected by objects around the vehicle. The first detection distance is calculated by the first detection sensor, which is the source of the transmission, receiving the reflected wave of the probe wave transmitted by the first detection sensor as a direct wave, and the second detection distance is calculated by the second detection sensor, which is different from the source, receiving the reflected wave of the probe wave transmitted by the first detection sensor as an indirect wave (S1). The third detection distance is calculated by the second detection sensor, which is the source, receiving the reflected wave of the probe wave transmitted by the second detection sensor as a direct wave. The system obtains the fourth detection distance (S1) calculated by receiving the reflected wave of the probe wave transmitted by the second detection sensor as an indirect wave at the first detection sensor, which is different from the source. If the first, second, third, and fourth detection distances satisfy predetermined conditions (S3-S5), the position coordinates of the object are determined by triangulation using either a combination of the first and second detection distances or a combination of the third and fourth detection distances (S7). Based on the determined position coordinates of the object, support is provided to the object (S11). Therefore, it is not necessary to determine the position coordinates of the object by triangulation with the first detection sensor as the source and the second detection sensor as the receiver, and to determine the position coordinates of the object by triangulation with the second detection sensor as the source and the first detection sensor as the receiver. Support can be provided to the object by determining only one of the position coordinates. As a result, support can be provided to the object quickly, and the processing load can be reduced. Furthermore, the predetermined conditions (S3~S5) are: the difference between the second detection distance and the fourth detection distance is within a threshold; the difference between the average value of the second detection distance and the fourth detection distance and the sum of the first detection distance and the third detection distance is 0 or greater; and the difference between the square of the average value of the second detection distance and the fourth detection distance and the square of the sum of the first detection distance and the third detection distance is less than or equal to the square of the inter-sensor distance, which is the distance between the first detection sensor and the second detection sensor; and the square of the difference between the second detection distance and the first detection distance is less than or equal to the sum of the square of the first detection distance and the square of the inter-sensor distance. Furthermore, the following conditions must be met: the square of the first detection distance is less than or equal to the sum of the square of the difference between the second and first detection distances and the square of the distance between sensors; the square of the difference between the fourth and third detection distances is less than or equal to the sum of the square of the third detection distance and the square of the distance between sensors; and the square of the third detection distance is less than or equal to the sum of the square of the difference between the fourth and third detection distances and the square of the distance between sensors. This makes it possible to accurately determine when two adjacent detection sensors are detecting the same object. In addition, by detecting different objects with direct and indirect waves, it is possible to prevent assistance from being provided to an object in the case of a ghost detection state where the object is calculated to be in a different location than its actual location. Furthermore, the system includes a first detection sensor (e.g., ultrasonic sensor 9B) and a second detection sensor (e.g., ultrasonic sensor 9A) installed at different locations relative to the vehicle 2, which transmit probe waves around the vehicle 2 and are positioned to mutually receive received waves including reflected waves from objects around the vehicle 2, and a third detection sensor (e.g., ultrasonic sensor 9C) installed in the opposite direction from the second detection sensor relative to the first detection sensor, which transmits probe waves around the vehicle and is positioned to mutually receive received waves including reflected waves from objects around the vehicle, at least with the first detection sensor, and a first detection distance calculated by the first detection sensor receiving the reflected wave of the probe wave transmitted by the first detection sensor as a direct wave, and a second detection sensor, which is different from the source, receiving the reflected wave of the probe wave transmitted by the first detection sensor as an indirect wave. The system obtains the second detection distance calculated by (S1) and the third detection distance calculated by receiving the reflected wave of the probe wave transmitted by the first detection sensor as an indirect wave at a third detection sensor different from the source (S1). If the first, second, and third detection distances satisfy predetermined conditions (S8), the system identifies the position coordinates of the object by triangulation using either a combination of the first and second detection distances or a combination of the first and third detection distances (S10). Based on the identified position coordinates of the object, the system provides support to the object (S11). Therefore, it is not necessary to identify the position coordinates of the object by triangulation with the first detection sensor as the source and the second detection sensor as the receiver, nor is it necessary to identify the position coordinates of the object by triangulation with the first detection sensor as the source and the third detection sensor as the receiver. Support can be provided to the object by identifying only one of the position coordinates. As a result, support to the object can be provided quickly, and the processing load can be reduced. Furthermore, if the first angle is defined as the angle between the first side connecting the installation position of the first detection sensor to the installation position of the second detection sensor and the second side connecting the position of the first detection sensor to the position of the object, the second angle is defined as the angle between the third side connecting the installation position of the first detection sensor to the installation position of the third detection sensor and the second side, and the third angle is defined as the angle between the first side and the third side, then the predetermined condition (S9) is the condition that the sum of the first angle calculated from the first detection distance and the second detection distance, the second angle calculated from the first detection distance and the third detection distance, and the third angle is 360 degrees, then it becomes possible to accurately determine when three adjacent detection sensors are each detecting the same object. In addition, by detecting different objects with direct waves and indirect waves, it becomes possible to prevent assistance from being provided to the object when a ghost detection state occurs in which the object is calculated to be located at a different position than its actual location.

[0089] It should be noted that the present invention is not limited to the embodiments described above, and various improvements and modifications are possible without departing from the spirit of the invention. For example, in this embodiment, the assistance provided to the target object by the driving assistance processing program shown in Figure 9 is always performed whether the vehicle is moving or stopped, but it may be set to be performed only when the vehicle is driving with automated driving assistance. Alternatively, it may be set to be performed only when the vehicle is performing parking assistance, which is one of the automated driving assistance functions.

[0090] Furthermore, in this embodiment, four ultrasonic sensors 9A to 9D are installed on the front of the vehicle 2 to detect objects, but the number of ultrasonic sensors does not necessarily have to be four; for example, there could be two. The same applies to the ultrasonic sensors 9I to 9L installed on the rear of the vehicle.

[0091] Furthermore, in this embodiment, the driver assistance processing program (Figure 9) is executed by the driver assistance ECU 10 of the driver assistance device 1, but the execution entity can be changed as appropriate. For example, the execution may be performed by the control unit of the liquid crystal display 4, the vehicle control ECU, the control unit of the navigation system, or other in-vehicle devices.

[0092] [Note] The embodiments described above also disclose the following inventions. In the following description, the names and expressions of corresponding components in the embodiments, as well as the reference numerals used in the drawings, are indicated in parentheses for reference. However, the components of each invention are not limited to these indications.

[0093] (Invention A) The driving support device (1) according to claim 1, wherein when the first detection distance (d1), the second detection distance (l1), the third detection distance (d2), and the fourth detection distance (l2) satisfy predetermined conditions (S3 to S5), the position coordinates of the object are determined by triangulation using the combination of the first detection distance and the second detection distance or the combination of the third detection distance and the fourth detection distance, whichever is more reliable in determining the position coordinates of the object.

[0094] This method reduces the processing burden associated with determining the position coordinates of an object using triangulation, while also enabling the accurate determination of the object's position coordinates.

[0095] (Invention B) The driving support device (1) according to claim 3, wherein, when the first detection distance (d1), the second detection distance (l1), and the third detection distance (l2) satisfy a predetermined condition (S8), the position coordinates of the object are determined by triangulation using the combination of the first detection distance and the second detection distance or the combination of the first detection distance and the third detection distance that is more reliable in determining the position coordinates of the object.

[0096] This method reduces the processing burden associated with determining the position coordinates of an object using triangulation, while also enabling the accurate determination of the object's position coordinates. [Explanation of symbols]

[0097] 1...Driving assistance system, 2...Vehicle, 9A~9L...Ultrasonic sensor (detection sensor), 10...Driving assistance ECU, 15...Target object

Claims

1. The system includes a first detection sensor and a second detection sensor, each installed at different locations relative to the vehicle, which transmit probe waves to the area around the vehicle and are positioned in a manner that allows them to mutually receive received waves, including reflected waves that have been reflected by objects around the vehicle. The first detection distance is calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as a direct wave at the transmitting first detection sensor, and the second detection distance is calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as an indirect wave at a second detection sensor different from the transmitting source. The system obtains a third detection distance calculated by receiving the reflected wave of the exploration wave transmitted by the second detection sensor as a direct wave at the transmitting second detection sensor, and a fourth detection distance calculated by receiving the reflected wave of the exploration wave transmitted by the second detection sensor as an indirect wave at a first detection sensor different from the transmitting source. When the first detection distance, the second detection distance, the third detection distance, and the fourth detection distance satisfy predetermined conditions, the position coordinates of the object are determined by triangulation using either a combination of the first detection distance and the second detection distance or a combination of the third detection distance and the fourth detection distance. A driving support device that provides assistance to the identified object based on the position coordinates of the object.

2. The aforementioned predetermined conditions are: The difference between the second detection distance and the fourth detection distance is within the threshold. The difference between the average value of the second detection distance and the fourth detection distance and the sum of the first detection distance and the third detection distance is 0 or greater, and the difference between the square of the average value of the second detection distance and the fourth detection distance and the square of the sum of the first detection distance and the third detection distance is less than or equal to the square of the inter-sensor distance, which is the distance between the first detection sensor and the second detection sensor. The square of the difference between the second detection distance and the first detection distance is less than or equal to the sum of the square of the first detection distance and the square of the distance between the sensors, and the square of the first detection distance is less than or equal to the sum of the square of the difference between the second detection distance and the first detection distance and the square of the distance between the sensors, and the square of the difference between the fourth detection distance and the third detection distance is less than or equal to the sum of the square of the third detection distance and the square of the distance between the sensors, and the square of the third detection distance is less than or equal to the sum of the square of the difference between the fourth detection distance and the third detection distance and the square of the distance between the sensors, The driving assistance device according to claim 1, which satisfies all of the conditions.

3. A first detection sensor and a second detection sensor are installed at different locations on the vehicle, respectively, and are positioned in a manner that allows them to transmit probe waves to the area around the vehicle and to mutually receive received waves, including reflected waves that have been reflected by objects around the vehicle. The system includes a third detection sensor, which is positioned opposite to the second detection sensor relative to the first detection sensor, transmits a search wave to the area around the vehicle, and is positioned such that it can mutually receive received waves, including reflected waves, that have been reflected by objects around the vehicle, from the search wave. The first detection distance is calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as a direct wave at the transmitting first detection sensor, the second detection distance is calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as an indirect wave at a second detection sensor different from the transmitting source, and the third detection distance is calculated by receiving the reflected wave of the exploration wave transmitted by the first detection sensor as an indirect wave at a third detection sensor different from the transmitting source. When the first detection distance, the second detection distance, and the third detection distance satisfy predetermined conditions, the position coordinates of the object are determined by triangulation using either a combination of the first detection distance and the second detection distance or a combination of the first detection distance and the third detection distance. A driving support device that provides assistance to the identified object based on the position coordinates of the object.

4. The first angle is defined as the angle between the first side, which connects the installation position of the first detection sensor to the installation position of the second detection sensor, and the second side, which connects the position of the first detection sensor to the position of the object. The second angle is defined as the angle between the third side, which connects the installation position of the first detection sensor to the installation position of the third detection sensor, and the second side. If the angle between the first side and the third side is defined as the third angle, The aforementioned predetermined conditions are: The driving assistance device according to claim 3, wherein the condition is that the sum of the first angle calculated by the first detection distance and the second detection distance, the second angle calculated by the first detection distance and the third detection distance, and the third angle is 360 degrees.

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