Drive assist device

Abstract

To provide a drive assist device for preventing wrong support for a nonexisting object from being performed in a state in which a foreign matter, such as waterdrops, is not adhered to the surface of a detection sensor.SOLUTION: While a drive assist device supports a driver for an object when a located position of the object is within a support object area 15 after locating the position of the object on the basis of detection results of respective ultrasonic sensors 3 to 6 installed for a vehicle 2, an area in which the sum of distance to each position of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is equal to or less than first distance and the distance to the third ultrasonic sensor 5 becomes second distance or longer is excluded from the support object area 15 when detecting an object by a combination of for example the third ultrasonic sensor 5 in a transmission side and the second ultrasonic sensor 4 in a reception side.SELECTED DRAWING: Figure 6

Description

Technical Field

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

Background Art

[0002] Conventionally, as a safety device for ensuring safety when a vehicle is traveling or parked, detection sensors such as ultrasonic sensors, millimeter-wave radar sensors, and LiDAR sensors are arranged on the vehicle to detect surrounding objects (for example, people, bicycles, other vehicles, walls, etc.), and based on the detection results of the detection sensors, a technique for warning the driver or automatically controlling the vehicle is known.

[0003] Such a detection sensor outputs a probing wave such as ultrasonic waves, millimeter waves, or infrared rays, and measures the time until the output probing wave is reflected by an object and returns, thereby detecting the distance to the object. Also, if a plurality of detection sensors are arranged on the vehicle, it becomes possible to use indirect waves in addition to direct waves, and more accurate detection of the object becomes possible. Note that the "direct wave" refers to the received wave when the detection sensor that transmitted the probing wave and the detection sensor that received the reflected wave of the probing wave by the object as the received wave are the same. On the other hand, the "indirect wave" refers to the received wave when the detection sensor that transmitted the probing wave and the detection sensor that received the reflected wave of the probing wave by the object as the received wave are different.

[0004] However, when foreign substances such as water droplets adhere to the surface of the detection sensor in bad weather, the probing wave is output in an unexpected direction (for example, vertically downward or directly sideways) by the foreign substance, and for example, the distance to the ground is misdetected as the distance to an object in front (recognizing that there is an object when there is no object). Therefore, for example, Japanese Patent No. 7192647 discloses a technique for detecting an object at a very short distance by direct waves and determining that a foreign substance is attached to the detection sensor when a state where indirect waves cannot be received continues for a predetermined time or more.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent No. 7192647 (Paragraphs 0055 - 0058) [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] Here, in the above Patent Document 1, it is a condition for the detection sensor to determine that a foreign object is attached when it detects that the object is detected at a very close distance by the direct wave and the state where the indirect wave cannot be received continues for a predetermined time or more. However, under the above conditions, it may not be possible to accurately determine the attachment of a foreign object to the detection sensor. For example, as shown in FIG. 11, even if the detection sensor S1 can receive the exploration wave output from the detection sensor S2 as an indirect wave, when a foreign object is attached to the surface of the detection sensor S2, the exploration wave may be output vertically downward or directly sideways, which is not originally assumed by the foreign object. Therefore, the indirect wave may become the exploration wave directly received without being reflected by the object, or may become the exploration wave received after being reflected by the ground instead of the object. When such an indirect wave is received, there is a possibility that an object that does not actually exist may be recognized as being at a very close distance. However, with the technology of the above Patent Document 1, it is not possible to determine that a foreign object is attached to the detection sensor. That is, there is still a possibility that a warning for a non - existent object or automatic control of the vehicle may be performed.

[0007] The present invention has been made to solve the above - mentioned conventional problems, and an object of the present invention is to provide a driving support device that prevents incorrect assistance from being provided to non - existent objects when foreign objects such as water droplets are attached to the surface of a detection sensor. [Means for Solving the Problems]

[0008] To achieve the above object, the driving support device according to the present invention includes a first detection sensor and a second detection sensor that are respectively installed at different positions with respect to a vehicle, transmit detection waves around the vehicle, and are in a positional relationship where they can mutually receive received waves including reflected waves reflected by an object around the vehicle; a position specifying means for specifying the position of the object based on the detection results of the first detection sensor and the second detection sensor; and a support means for supporting the driver with respect to the object when the position of the object specified by the position specifying means is located within a support target area. An area where the sum of the distances to the respective positions of the first detection sensor and the second detection sensor is equal to or less than a first distance and the distance to the first detection sensor is equal to or greater than a second distance is excluded from the support target area.

Effect of the Invention

[0009] According to the driving support device according to the present invention having the above configuration, by excluding in advance from the support target area a position where an object that should not exist in a state where foreign matter such as water droplets adheres to the surface of the detection sensor is likely to be specified, it is possible to prevent incorrect support from being performed for an object that does not exist.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0011] Hereinafter, an embodiment in which the driving support device according to the present invention is embodied 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. FIG. 1 is a front view of the vehicle 2 according to the present embodiment as viewed from the front, and FIG. 2 is a top view of the vehicle 2 according to the present embodiment as viewed from above (only in the vicinity of the front).

[0012] Here, the vehicle 2 may be, for example, an automobile (internal combustion engine vehicle) having an internal combustion engine (engine, etc.) as a drive source, an automobile (electric vehicle, fuel cell vehicle, etc.) having an electric motor (motor, etc.) as a drive source, or an automobile (hybrid vehicle) having both of them as drive sources. Also, regardless of the vehicle type, it may be a passenger car, or a commercial large truck, bus, construction machinery, etc. Further, in the following description, a four-wheel vehicle is assumed, but a two-wheel or three-wheel vehicle may also be used. Also, as will be described later, as one of the safety devices, when an object (for example, a person, a bicycle, another vehicle, a wall, etc.) is detected in the support target area set in the front space of the vehicle 2, the vehicle 2 has a function of providing support to the driver for the object (for example, warning by sound, display on the in-vehicle display, deceleration control of the vehicle, etc.), which is executed by the driving support device 1. Note that the details of the driving support device 1 will be described later.

[0013] Also, as shown in FIG. 1, four ultrasonic sensors 3 to 6 are installed at different positions around the front bumper at the front of the vehicle 2 or around the front grille above it. Hereinafter, they will be referred to as the first ultrasonic sensor 3, the second ultrasonic sensor 4, the third ultrasonic sensor 5, and the fourth ultrasonic sensor 6 in order from the right when viewed from the front.

[0014] The ultrasonic sensors 3 to 6 transmit ultrasonic waves as detection waves to the surroundings of the vehicle 2, and detect the object that reflected the detection wave by receiving the reflected wave reflected by the object around the vehicle. Specifically, the distance to the object that reflected the detection wave is detected by measuring the time from transmission to reception. Also, the ultrasonic sensors 3 to 6 are configured to be able 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 of the driving support device 1 described later. Note that examples of the objects to be detected by the ultrasonic sensors 3 to 6 include people, bicycles, other vehicles, walls, and the like.

[0015] Also, although the installation positions and installation directions of the ultrasonic sensors 3 to 6 can be set as appropriate, in this embodiment, in order to set the front of the vehicle 2 in the traveling direction as the detection range of the object, as shown in FIG. 2, the transmission direction of the detection wave is the traveling direction of the vehicle. It is installed facing the front of the vehicle 2 so as to be in front. As shown in FIG. 1, the heights of the ultrasonic sensors 3 to 6 from the ground surface are made approximately the same, and they are installed at equal intervals without bias in the left-right direction so that detection waves can be transmitted over a wider range in front of the vehicle (that is, the detectable range of the object is made wider).

[0016] Specifically, as shown in FIG. 2, the first ultrasonic sensor 3 is installed near the left front corner of the vehicle 2 so as to transmit a detection wave to the left front of the vehicle 2, with the transmission direction of the detection wave inclined slightly to the left of the traveling direction of the vehicle 2. The second ultrasonic sensor 4 is installed slightly to the left of the center line of the vehicle 2 so as to transmit a detection wave mainly centered on the left side in front of the vehicle 2, with the transmission direction of the detection wave directed in the traveling direction of the vehicle. The third ultrasonic sensor 5 is installed slightly to the right of the center line of the vehicle 2 so as to transmit a detection wave mainly centered on the right side in front of the vehicle 2, with the transmission direction of the detection wave directed in the traveling direction of the vehicle. The fourth ultrasonic sensor 6 is installed near the right front corner of the vehicle 2 so as to transmit a detection wave to the right front of the vehicle 2, with the transmission direction of the detection wave inclined slightly to the right of the traveling direction of the vehicle 2. The first ultrasonic sensor 3 and the fourth ultrasonic sensor 6, and the second ultrasonic sensor 4 and the third ultrasonic sensor 5 are symmetrically arranged with the vehicle center line interposed therebetween in a plan view.

[0017] In addition, in this embodiment, the ultrasonic sensors 3 to 6 whose detection range of the object is the front in the traveling direction of the vehicle 2 will be described. However, it is also possible to similarly install ultrasonic sensors whose detection range of the object is the side or the rear of the vehicle 2.

[0018] Among the ultrasonic sensors 3 to 6, the first ultrasonic sensor 3 and the second ultrasonic sensor 4 are in a positional relationship where they can at least receive each other's received waves. That is, the second ultrasonic sensor 4 is in a positional relationship where it can receive the probing wave transmitted by the first ultrasonic sensor 3 as an indirect wave. Similarly, the first ultrasonic sensor 3 is in a positional relationship where it can receive the probing wave transmitted by the second ultrasonic sensor 4 as an indirect wave. Also, the second ultrasonic sensor 4 and the third ultrasonic sensor 5 are in a positional relationship where they can receive each other's received waves. That is, the third ultrasonic sensor 5 is in a positional relationship where it can receive the probing wave transmitted by the second ultrasonic sensor 4 as an indirect wave. Similarly, the second ultrasonic sensor 4 is in a positional relationship where it can receive the probing wave transmitted by the third ultrasonic sensor 5 as an indirect wave. Furthermore, the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6 are in a positional relationship where they can receive each other's received waves. That is, the fourth ultrasonic sensor 6 is in a positional relationship where it can receive the probing wave transmitted by the third ultrasonic sensor 5 as an indirect wave. Similarly, the third ultrasonic sensor 5 is in a positional relationship where it can receive the probing wave transmitted by the fourth ultrasonic sensor 6 as an indirect wave.

[0019] On the other hand, for combinations of ultrasonic sensors other than the above, basically, they are in a positional relationship where they cannot receive each other's received waves. For example, for the probing wave transmitted by the first ultrasonic sensor 3, the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6 are in a positional relationship where they cannot receive it as an indirect wave. Also, for the probing wave transmitted by the second ultrasonic sensor 4, the fourth ultrasonic sensor 6 is in a positional relationship where it cannot receive it as an indirect wave. Also, for the probing wave transmitted by the third ultrasonic sensor 5, the first ultrasonic sensor 3 is in a positional relationship where it cannot receive it as an indirect wave. Also, for the probing wave transmitted by the fourth ultrasonic sensor 6, the first ultrasonic sensor 3 and the second ultrasonic sensor 4 are in a positional relationship where they cannot receive it as an indirect wave.

[0020] In addition, the above "able to receive the received wave" means that the received wave can be received to such an extent that the distance to the object can be effectively detected. On the other hand, "unable to receive the received wave" includes not only the case where the received wave cannot be received at all, but also the reception of a received wave with a weak reception intensity that cannot effectively detect the distance to the object.

[0021] In this embodiment, ultrasonic sensors 3 to 6 can identify not only the distance to the object but also the specific position of the object (relative position with respect to the vehicle) by receiving direct waves and indirect waves as received waves. Hereinafter, the "direct wave" and the "indirect wave" are defined as follows. For example, among the received waves received by the first ultrasonic sensor 3, the received wave caused by the reflected wave of the exploration wave transmitted from the first ultrasonic sensor 3 by the object is referred to as the "direct wave". The direct wave is the received wave when the first ultrasonic sensor 3 receives, as the received wave, the reflected wave of the exploration wave transmitted from the first ultrasonic sensor 3 by the object. That is, the direct wave is the received wave when the ultrasonic sensor that transmits the exploration wave and the ultrasonic sensor that receives, as the received wave, the reflected wave of the exploration wave by the object are the same. On the other hand, among the received waves received by the first ultrasonic sensor 3, the received wave caused by the reflected wave of the exploration wave transmitted from an ultrasonic sensor other than the first ultrasonic sensor 3 (the second ultrasonic sensor 4 in this embodiment) by the object is referred to as the "indirect wave". The indirect wave is the received wave when the first ultrasonic sensor 3 receives, as the received wave, the reflected wave of the exploration wave transmitted from the second ultrasonic sensor 4 by the object. That is, the indirect wave is the received wave when the ultrasonic sensor that transmits the exploration wave and the ultrasonic sensor that receives, as the received wave, the reflected wave of the exploration wave by the object are different.

[0022] Next, regarding the method of specifying the specific position (relative position with respect to the vehicle) of the object 8 when the object 8 exists in front of the vehicle as shown in FIG. 3, an example will be given of the case where the position P(X, Y) of the object 8 is specified by the exploration wave transmitted from the second ultrasonic sensor 4. First, the second ultrasonic sensor 4 transmits by itself and receives the direct wave, which is the reflected wave reflected by the object 8, whereby the distance Dr from the second ultrasonic sensor 4 to the position P is measured. Also, when the first ultrasonic sensor 3 receives, as an indirect wave, the reflected wave of the exploration wave transmitted from the second ultrasonic sensor 4 reflected by the object, the sum of the distance Dr from the second ultrasonic sensor 4 to the position P and the distance Di from the first ultrasonic sensor 3 to the position P is measured. Also, the distance Db between the first ultrasonic sensor 3 and the second ultrasonic sensor 4 is a fixed value for each vehicle and can be obtained by inputting it in advance on the device side. As a result, the angles θ1 and θ2 between them can be calculated from the lengths of the three sides of Dr, Di, and Db, and the specific position coordinates (X, Y (relative position with respect to the vehicle)) of the position P of the object 8 can also be specified using triangulation. Incidentally, in the above example, the case where the position P(X, Y) of the object 8 is specified by the exploration wave transmitted from the second ultrasonic sensor 4 has been described, but the position P(X, Y) of the object 8 can be similarly specified by the exploration wave transmitted from another ultrasonic sensor (for example, the first ultrasonic sensor 3) at the position where the exploration wave reaches the object 8.

[0023] However, since the ultrasonic sensors 3 to 6 are installed on the outer wall of the vehicle 2, for example, foreign substances such as water droplets may adhere to the surfaces (ultrasonic transmission and reception surfaces) of the ultrasonic sensors 3 to 6 in bad weather. In such a case, there is a problem that the detection of the position of the object 8 as described above cannot be accurately performed. Here, FIG. 4 is a diagram showing the ultrasonic sensors 3 to 6 in a state of being installed on the outer wall of the vehicle 2.

[0024] The ultrasonic sensors 3 to 6 house electro-mechanical conversion elements such as piezoelectric elements inside a case formed of synthetic resin or the like, and have a substantially cylindrical outer shape with the detection axis X as the central axis. Note that the detection axis X is a virtual straight line extending along the transmission and reception direction of ultrasonic waves from the ultrasonic sensors 3 to 6. Further, the ultrasonic sensors 3 to 6 have a transmission and reception surface 10 for transmitting and receiving ultrasonic waves. The transmission and reception surface 10 is a substantially circular bottom surface or top surface in the substantially cylindrical outer shape of the ultrasonic sensors 3 to 6, and is formed in a planar shape with the detection axis X as the normal. Then, the ultrasonic sensors 3 to 6 are configured to transmit a probing wave along the detection axis X by ultrasonically vibrating the transmission and reception surface 10 based on a drive signal applied to the electro-mechanical conversion element. Further, when the ultrasonic sensors 3 to 6 receive a received wave from the outside, the ultrasonic sensors 3 to 6 are configured to generate, by the electro-mechanical conversion element, a reception signal which is an electric signal corresponding to the excitation state of the transmission and reception surface 10 due to the received ultrasonic wave.

[0025] Further, as shown in FIG. 4, the ultrasonic sensors 3 to 6 are inserted and installed in through holes formed in the outer wall of the vehicle 2 with the transmission and reception surface 10 exposed to the outside. Therefore, foreign matter 11 such as water droplets may adhere to the transmission and reception surface 10 of the ultrasonic sensors 3 to 6 in bad weather. In such a case, the probing wave transmitted from the above-described transmission and reception surface 10 may not necessarily be transmitted along the detection axis X, but may be transmitted in an unexpected direction such as vertically downward or directly sideways. As a result, as shown in FIG. 5, the direct wave or indirect wave received by the ultrasonic sensors 3 to 6 may be a probing wave reflected by the ground instead of the object. Alternatively, the indirect wave received by the ultrasonic sensors 3 to 6 may be a probing wave directly received from another ultrasonic sensor without being reflected by the object. Since the distance to the object measured based on such a direct wave or indirect wave becomes extremely short, an object that does not exist at the closest distance of the vehicle 2 may be detected as being present. As a result, there arises a problem that the above-described safety device provides support to the driver for an object that does not exist (for example, warning by sound, display on an in-vehicle display, deceleration control of the vehicle, etc.).

[0026] Therefore, in the present embodiment, when it is determined that the object is located, exclusion areas are set as follows for the support target area that is the target for assisting the driver. Note that the support target area is set for each combination of the ultrasonic sensors 3 to 6 on the transmission side and the reception side that can identify the position of the object among the ultrasonic sensors 3 to 6. The combination of the ultrasonic sensors 3 to 6 on the transmission side and the reception side that can identify the position of the object is a combination in a positional relationship where the received waves can be received from each other. For example, in the present embodiment, there are three combinations: the combination of the adjacent first ultrasonic sensor 3 and the second ultrasonic sensor 4, the combination of the second ultrasonic sensor 4 and the third ultrasonic sensor 5, and the combination of the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6. Furthermore, since there is also a pattern where the transmission side and the reception side are reversed, there are a total of six combinations.

[0027] Among the above six combinations, first, an example will be given and described for the support target area 15 set for the combination in which the third ultrasonic sensor 5 is the transmission side (the first detection sensor) and the second ultrasonic sensor 4 is the reception side (the second detection sensor) using FIG. 6. As shown in FIG. 6, the support target area 15 basically has a substantially rectangular shape that gradually expands in the left - right direction along the detection axis X of each sensor from the transmission - reception surfaces 10 of the second ultrasonic sensor 4 and the third ultrasonic sensor 5. The shape of the support target area 15 is set in consideration of the installation positions and directions of the respective sensors as well as the performance of the sensors. Also, the range of the support target area 15 is set relative to the vehicle 2. Then, the position coordinates of the object are identified by the combination of the detection result obtained by the third ultrasonic sensor 5 receiving the direct wave transmitted by itself and the detection result obtained by the second ultrasonic sensor 4 receiving the exploration wave transmitted from the third ultrasonic sensor 5 as an indirect wave (see FIG. 4). When the identified position coordinates of the object are located within the support target area 15, support for the driver is provided. However, for the support target area 15, an area where the sum of the distances to the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is less than or equal to the first distance L1 and the distance to the third ultrasonic sensor 5 is greater than or equal to the second distance L2 is excluded from the support target area 15. Specifically, the area where the sum of the distances to the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is less than or equal to the first distance L1 is within the range of the ellipse 16 with the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 as foci respectively, and the area where the distance to the third ultrasonic sensor 5 is greater than or equal to the second distance L2 is outside the range of the circle 17 with a radius of L2 centered on the position of the third ultrasonic sensor 5. Therefore, as shown in FIG. 6, the area excluded from the support target area 15 (hereinafter referred to as the exclusion area) is the area inside the ellipse 16 and outside the circle 17. Note that not providing support to the driver when the position of the object is in the above exclusion area means, in other words, not providing support to the driver when the distance to the object detected based on the indirect wave is less than or equal to the first distance L1 and the distance to the object detected based on the direct wave is greater than or equal to the second distance L2.

[0028] Here, the first distance L1 is the distance obtained by adding the distance α considering the measurement error to the distance obtained by correcting the distance between the second ultrasonic sensor 4 and the third ultrasonic sensor 5 according to the characteristics of the second ultrasonic sensor 4 and the third ultrasonic sensor 5. For example, if the distance between the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is W, the first distance L1 is defined by the following formula (1). L1 = W / cosθ + α ···(1) Note that θ is a unique value of the sensor. Also, α is determined by the accuracy of the sensor, and a smaller value is set for a sensor with better accuracy. For example, let α = 100 mm.

[0029] The distance W between the second ultrasonic sensor 4 and the third ultrasonic sensor 5 corresponds to the detected distance (Dr + Di in FIG. 3) when the exploration wave transmitted from the third ultrasonic sensor 5 to the second ultrasonic sensor 4 without being reflected by the object is directly received as an indirect wave as shown in FIG. 5. However, even when the exploration wave transmitted from the second ultrasonic sensor 4 is directly received as an indirect wave, as shown in FIG. 7, the exploration wave does not reach at the shortest distance but reaches along a curved trajectory specific to the sensor. Therefore, the detected distance is not W but exactly W / cosθ (>W). Accordingly, excluding from the support target area 15 the area where the sum of the distances to the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is equal to or less than the first distance L1 is to prevent support for the object from being performed when the object is erroneously identified as being located at the closest distance due to the exploration wave transmitted from the second ultrasonic sensor 4 being directly received as an indirect wave.

[0030] On the other hand, the second distance L2 is the shorter distance when comparing the distance M1 obtained by subtracting the distance α considering the measurement error from the installation height of the third ultrasonic sensor 5 with respect to the ground and the distance M2 which is a distance that has been previously found to be erroneously detected as the distance to the object when the third ultrasonic sensor 5 itself receives the exploration wave transmitted in a state where water droplets are attached to the transmission / reception surface 10 of the third ultrasonic sensor 5. Note that M2 is a characteristic value of the sensor specified based on the verification results previously performed by the manufacturer side and is, for example, 260 mm. And, for example, when the installation height of the third ultrasonic sensor 5 is H, the second distance L2 is defined by the following formula (2). M2 = MIN(H - α, 260 mm) ····(2) Note that α is determined by the accuracy of the sensor, and a smaller value is set for a sensor with better accuracy. For example, let α = 100 mm.

[0031] The installation height H of the third ultrasonic sensor 5 corresponds to the detected distance (Dr in FIG. 3) when the detection wave is received directly as a reflected wave on the ground instead of the object as shown in FIG. 5. Here, even if foreign matter such as water droplets adheres to the transmission / reception surface 10 of the third ultrasonic sensor 5 and the detection wave is output in a vertical downward direction or any other direction, and even if a non-existent object is erroneously detected, if there is no object, the distance to the detected object will be such that L2 is the minimum distance, and basically, a distance shorter than L2 will not be detected. That is, when it is detected that an object is located in an area where the distance to the third ultrasonic sensor 5 is shorter than the second distance L2, it is highly likely that an actual object is located at that position. Therefore, even if the sum of the distances to the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is equal to or less than the first distance L1, when it is detected that an object is located in an area where the distance to the third ultrasonic sensor 5 is smaller than the second distance L2, assistance for the object is to be provided.

[0032] However, for the above exclusion area, assistance is not provided when the position coordinates at the time when the object is first detected (when the object is first recognized) are located in the exclusion area. However, when the position coordinates at the time when the object is first detected are in the support target area 15 that is not the exclusion area and then the vehicle or the object moves to be located in the exclusion area, it is desirable to continue providing assistance even if the object is in the exclusion area.

[0033] Also, in FIG. 6, the support target area 15 set for the combination with the third ultrasonic sensor 5 as the transmission side (the first detection sensor) and the second ultrasonic sensor 4 as the reception side (the second detection sensor) was described. However, support target areas 15 are also set for other combinations respectively, and similarly, exclusion areas are also set. For example, FIG. 8 shows the support target area 15 set for the combination with the fourth ultrasonic sensor 6 as the transmission side (the first detection sensor) and the third ultrasonic sensor 5 as the reception side (the second detection sensor).

[0034] The position coordinates of the object are specified by combining the detection result obtained by the fourth ultrasonic sensor 6 receiving the direct wave transmitted by itself and the detection result obtained by the third ultrasonic sensor 5 receiving the exploration wave transmitted from the fourth ultrasonic sensor 6 as an indirect wave (see FIG. 4). When the specified position coordinates of the object are located within the support target area 15 shown in FIG. 8, support for the driver is provided. Further, regarding the support target area 15 shown in FIG. 8, an area where the sum of the distances to the positions of the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6 is equal to or less than the first distance L1 and the distance to the fourth ultrasonic sensor 6 is equal to or greater than the second distance L2 is excluded from the support target area 15. Specifically, the area where the sum of the distances to the positions of the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6 is equal to or less than the first distance L1 is within the range of the ellipse 18 with the positions of the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6 as foci, respectively, and the area where the distance to the fourth ultrasonic sensor 6 is equal to or greater than the second distance L2 is outside the range of the circle 19 with a radius of L2 centered on the position of the third ultrasonic sensor 5. Therefore, as shown in FIG. 8, the exclusion area excluded from the support target area 15 is the area inside the ellipse 18 and outside the circle 19.

[0035] Although illustration is omitted, support target areas 15 are similarly set for each of the other four combinations other than the two combinations described above, and exclusion areas are similarly set.

[0036] Subsequently, the driving support device 1 provided in the vehicle 2 described above will be described. The driving support device 1 is a device for providing support to the driver for the object (for example, a person, a bicycle, another vehicle, a wall, etc.) when it is detected that the object is located within the above-described support target area 15 set in the front space of the vehicle 2 described above (for example, warning by sound, display on the in-vehicle display, deceleration control of the vehicle, etc.). FIG. 9 is a block diagram showing the configuration of the driving support device 1 according to the present embodiment.

[0037] As shown in FIG. 9, when the driving support device 1 according to the present embodiment detects that an object is located within the support target area 15, it includes a liquid crystal display 21 that displays a warning to the object for the occupant of the vehicle 2, a speaker 22 that also outputs a warning sound to the object, a vehicle information DB 23 in which various data related to the vehicle 2 is recorded, and a driving support ECU 24 that performs various arithmetic processes based on the input information. Further, the driving support device 1 is connected via an in-vehicle network such as CAN to a first ultrasonic sensor 3, a second ultrasonic sensor 4, a third ultrasonic sensor 5, a fourth ultrasonic sensor 6 installed in the vehicle 2, a vehicle control ECU 25 that performs various controls on the vehicle 2, a vehicle speed sensor 26, a steering sensor 27, a shift position sensor 28, and other various sensors.

[0038] The liquid crystal display 21 is provided on the instrument panel of the vehicle 2 and displays a warning screen for notifying the occupant of the vehicle 2 of the presence of the object when, for example, it detects that the object is located within the support target area 15. Further, an imaging image obtained by imaging the periphery of the object with an in-vehicle camera installed in the vehicle may be displayed in order to make the occupant recognize the presence of the object. Note that the liquid crystal display 21 may be shared with that used for the navigation device.

[0039] Also, when the speaker 22 detects that an object is located within the support target area 15 based on an instruction from the driving support ECU 24, it outputs a warning sound or the like for notifying the occupant of the vehicle 2 of the presence of the object. Note that the speaker 22 may be shared with that used for the navigation device.

[0040] The vehicle information DB 23 is a storage means for storing various types of information regarding the vehicle 2. For example, the installation positions (height from the ground surface, positions in the left - right direction), detection axes X, overall length, vehicle width, wheelbase, minimum turning radius, etc. of the ultrasonic sensors 3 - 6 installed in the vehicle 2 are stored. These pieces of information are input in advance by the occupants or the people on the vehicle manufacturer's side. As the storage medium of the vehicle information DB 23, for example, a memory card can be used. Alternatively, it may be provided in the storage area (e.g., RAM or flash memory) within the driving support ECU 24.

[0041] On the other hand, the driving support ECU (Electronic Control Unit) 24 is an electronic control unit that controls the entire driving support device 1, and includes a CPU 31 as an arithmetic device and a control device, and a RAM 32 that is used as a working memory when the CPU 31 performs various arithmetic processes and stores route data, etc. when a route is searched, in addition to a control program, a ROM 33 in which a driving support program (see FIG. 10) described later, etc. are recorded, and an internal storage device such as a flash memory 34 that stores the program read from the ROM 33. Note that the driving support ECU 24 has various control units as processing algorithms. For example, the position specifying means specifies the position of the object based on the detection results of the ultrasonic sensors 3 - 6. The support means provides support to the driver for the object when the position of the object specified by the position specifying means is within the support target area 15.

[0042] The vehicle control ECU 25 is an electronic control unit that controls the vehicle 2. The vehicle control ECU 25 is connected to each drive unit of the vehicle such as the steering, brakes, and accelerator. In this embodiment, for example, when it is detected that an object is located within the support target area 15, automatic control of the vehicle 2 is implemented by controlling each drive unit. Specifically, control is performed to avoid contact with the object. For example, it may be brake control to decelerate the vehicle speed, or control to suppress an increase in the vehicle speed (acceleration prevention). Alternatively, it may be steering control to move away from the object. Note that the above vehicle control may be performed in parallel with the warnings by the liquid crystal display 21 and the speaker 22, or only one of the warnings by the liquid crystal display 21 and the speaker 22 and the vehicle control may be performed.

[0043] The vehicle speed sensor 26 is an active wheel speed sensor attached to the wheels of the vehicle 2, and detects the rotational speed of the wheels and outputs a speed signal. The steering sensor 27 is attached inside the steering device, and detects the steering angle when the steering wheel is steered and outputs a steering angle signal. Further, the shift position sensor 28 is built into the shift lever and detects which position among "P (parking)", "N (neutral)", "R (reverse)", "D (drive)", "2 (second gear)", and "L (low)" the shift position is in.

[0044] Based on the output signals from the above various sensors, the driving support ECU 24 can acquire the current vehicle speed, steering angle, shift position, etc. of the vehicle 2, and it is also possible to provide more appropriate support to the driver with respect to the object using these.

[0045] Next, a driving support processing program executed by the driving support ECU 24 in the driving support device 1 having the above configuration will be described with reference to FIG. 10. FIG. 10 is a flowchart of the driving support processing program according to the present embodiment. Here, the driving support processing program is executed after the ACC power supply (accessory power supply) of the vehicle 2 is turned on, and detects an object (for example, a person, a bicycle, another vehicle, a wall, etc.) around the vehicle 2 using the ultrasonic sensors 3 to 6. In particular, when it is detected that the object is located within the support target area 15, it is a program for supporting the driver with respect to the object. Note that the program shown in the flowchart in FIG. 10 below is stored in the RAM 32 and the ROM 33 provided in the driving support device 1 and is executed by the CPU 31.

[0046] Here, the following processes S1 to S6 are executed for each combination of the ultrasonic sensors 3 to 6 on the transmission side and the reception side that can specify the position of the object among the ultrasonic sensors 3 to 6 provided in the vehicle 2. The combination of the ultrasonic sensors 3 to 6 on the transmission side and the reception side that can specify the position of the object is, that is, a combination in a positional relationship where the received waves can be received by each other. For example, in the present embodiment, there are three combinations: the combination of the adjacent first ultrasonic sensor 3 and the second ultrasonic sensor 4, the combination of the second ultrasonic sensor 4 and the third ultrasonic sensor 5, and the combination of the third ultrasonic sensor 5 and the fourth ultrasonic sensor 6. Furthermore, since there is also a pattern in which the transmission side and the reception side are reversed, there are a total of six combinations. After selecting these six combinations, the following processes S1 to S6 are performed in parallel for each selected combination.

[0047] First, in step (hereinafter abbreviated as S) 1, the CPU 31 acquires an output signal (detection result) from the sensor of the target combination (hereinafter referred to as the target sensor) among the ultrasonic sensors 3 to 6 installed in the vehicle 2. As described above, the ultrasonic sensors 3 to 6 are installed so that the front in the traveling direction of the vehicle 2 is the detection range (FIG. 2), and 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 driving support ECU 24.

[0048] Subsequently, in S2, the CPU 31 determines whether an object has been detected based on the output signal from the target sensor acquired in the aforementioned S1. Specifically, when there is a received intensity strong enough to detect the distance to the object for the direct wave or indirect wave received by the target sensor, it is determined that the object has been detected. Examples of objects to be detected by the ultrasonic sensors 3 to 6 include, for example, people, bicycles, other vehicles, walls, etc. However, even if it is determined in the aforementioned S2 that an object has been detected, it is not necessarily the case that there is actually an object. For example, as shown in FIG. 5, when a reflected wave reflected from the ground is received or when an exploration wave is directly received from another sensor, it may be determined in the aforementioned S2 that an object has been detected.

[0049] And when it is determined that an object has been detected (S2: YES), the process proceeds to S3. On the other hand, when it is determined that an object has not been detected (S2: NO), the process ends without providing assistance to the driver.

[0050] In S3, the CPU 31 specifies the position coordinates of the specific object based on the output signal from the target sensor acquired in the aforementioned S1. Note that the method for specifying the position coordinates of the object based on the output signal from the target sensor has already been described with reference to FIG. 3, so the details are omitted.

[0051] Thereafter, in S4, the CPU 31 determines whether the position coordinates of the object specified in the aforementioned S3 are located within the support target area 15. Note that as described above, an exclusion area is set in the support target area 15 (FIGS. 6 and 8), and even if an object is located in the exclusion area, it is not considered to be located within the support target area 15. Also, since different areas are set for the support target area 15 and the exclusion area for each combination of target sensors, in the aforementioned S4, it is determined whether the position of the object is located within the support target area 15 using the support target area 15 set for the combination of target sensors.

[0052] And when it is determined that the position coordinates of the object specified in S3 are located within the support target area 15 (S4: YES), the process proceeds to S5. In S5, support is provided to the driver for the object determined to be located in the support target area 15. For example, a warning screen for notifying the occupant of the vehicle 2 of the presence of the object is displayed on the liquid crystal display 21. Also, a warning sound or the like for notifying the occupant of the vehicle 2 of the presence of the object is output from the speaker 22. Alternatively, a control signal is transmitted to the vehicle control ECU 25 to perform vehicle control for avoiding contact with the object.

[0053] Also, when it is determined that the position coordinates of the object specified in S3 are located outside the support target area 15 (S4: NO), the process basically ends without providing support to the driver. However, exceptionally, if the position coordinates at the time when the object was first detected are in the support target area 15 that is not the exclusion area and then the vehicle or the object moves to be located in the exclusion area, the support continues to be provided even if the object is within the exclusion area (S6: YES).

[0054] 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 the present embodiment, ultrasonic sensors 3 to 6 are respectively installed at different positions on the vehicle 2, and while transmitting a probing wave to the periphery of the vehicle, they are in a positional relationship where they can mutually receive a received wave including a reflected wave reflected by an object around the vehicle. Based on the detection results of each of the ultrasonic sensors 3 to 6, the position of the object is specified (S3). When the position of the specified object is located within the support target area 15, support is provided to the driver for the object (S5). On the other hand, for example, when detecting an object in a combination where the third ultrasonic sensor 5 is the transmission side and the second ultrasonic sensor 4 is the reception side, an area where the sum of the distances to the positions of the second ultrasonic sensor 4 and the third ultrasonic sensor 5 is equal to or less than the first distance and the distance to the third ultrasonic sensor 5 is equal to or greater than the second distance is excluded from the support target area 15. Therefore, it is possible to exclude in advance from the support target area a position where an object that should not exist in a state where foreign matter such as water droplets adheres to the surface of the ultrasonic sensor may be specified. As a result, it is possible to prevent incorrect support from being provided for an object that does not exist. Also, when a plurality of ultrasonic sensors 3 to 6 are installed on the vehicle 2, a possible combination as a combination of sensors for detecting an object is selected from the plurality of ultrasonic sensors 3 to 6. For each selected combination of sensors, the position of the object is specified based on the detection results of the sensors (S3), and using the support target area 15 set for the combination of sensors, it is determined whether the position of the object is located within the support target area 15 (S4). Therefore, even in a vehicle equipped with a large number of ultrasonic sensors, it is possible to set an appropriate support target area for each combination of sensors for specifying the position of the object. Also, the first distance L1 is a distance obtained by adding a distance considering a measurement error to a distance obtained by correcting the distance between the sensors of the target sensor according to the characteristics of the sensors. This is to prevent support from being provided to an object when it is erroneously specified that the object is located at the closest distance by directly receiving a probing wave transmitted from another sensor as an indirect wave. Further, the second distance L2 is either the distance obtained by subtracting the distance considering the measurement error from the installation height of the sensor with respect to the ground, or the distance that may be erroneously detected as the distance to the object by the sensor itself receiving the exploration wave transmitted with water droplets on the surface of the sensor. Therefore, even if the distance to the object detected by the sensor receiving the indirect wave is short, if the distance to the object detected by the sensor receiving the direct wave is extremely short, it can be highly estimated that the actual object is likely to be located, and it becomes possible to provide assistance to the object.

[0055] Note that the present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, four ultrasonic sensors 3 to 6 for detecting an object are installed on the front surface of the vehicle 2. However, the number of ultrasonic sensors does not necessarily have to be four as long as there are a plurality of them, and for example, two may be sufficient. Note that the number of combinations of target sensors varies according to the number of ultrasonic sensors, and the support target area 15 is set for each combination.

[0056] Further, in the present embodiment, the ultrasonic sensors 3 to 6 for detecting an object in front of the vehicle 2 in the traveling direction are provided, and the support target area 15 set in front of the vehicle 2 in the traveling direction has been described. However, ultrasonic sensors for detecting an object on the side or rear of the vehicle 2 may be provided. In that case, it is also possible to set a support target area in consideration of the exclusion area on the side or rear of the vehicle 2 in the same manner.

[0057] Further, in the present embodiment, the ultrasonic sensors 3 to 6 are used as the sensors for detecting the object. However, instead of the ultrasonic sensors 3 to 6, a millimeter-wave radar sensor that transmits millimeter waves as the exploration wave or a LiDAR sensor that transmits infrared rays as the exploration wave may be used.

[0058] Further, in this embodiment, even if the distance to the object detected based on the indirect wave is equal to or less than the first distance and the distance to the object detected based on the direct wave is equal to or greater than the second distance, the position coordinates of the object are specified (S3). If the specified position coordinates of the object are located in the exclusion area, no assistance is provided for the object (S4: NO, S6: NO). However, for the case where the distance to the object detected based on the indirect wave is equal to or less than the first distance and the distance to the object detected based on the direct wave is equal to or greater than the second distance, the specification (S3) of the position of the object itself may not be performed.

[0059] Also, in this embodiment, the driving support ECU 24 of the driving support device 1 executes the processing of the driving support processing program (FIG. 10), but the execution entity can be appropriately changed. For example, it may be configured to be executed by the control unit of the liquid crystal display 21, the vehicle control ECU, the control unit of the navigation device, or other in-vehicle devices.

Description of Reference Numerals

[0060] 1... Driving support device, 2... Vehicle, 3... First ultrasonic sensor, 4... Second ultrasonic sensor, 5... Third ultrasonic sensor, 6... Fourth ultrasonic sensor, 8... Object, 15... Support target area, 21... Liquid crystal display, 22... Speaker, 24... Driving support ECU, 25... Vehicle control ECU, 31... CPU, 32... RAM, 33... ROM

Claims

1. A first detection sensor and a second detection sensor that are respectively installed at different positions with respect to a vehicle, transmit a detection wave around the vehicle, and are in a positional relationship where they can receive each other's received waves including reflected waves reflected by an object around the vehicle; Position specifying means for specifying the position of the object based on the detection results of the first detection sensor and the second detection sensor; Support means for supporting the driver with respect to the object when the position of the object specified by the position specifying means is located within the support target area, and having, A driving support device that excludes from the support target area an area where the sum of the distances to each position of the first detection sensor and the second detection sensor is equal to or less than a first distance and the distance to the first detection sensor is equal to or greater than a second distance.

2. When a plurality of detection sensors are installed with respect to a vehicle, a combination possible as a combination of the first detection sensor and the second detection sensor is selected from the plurality of detection sensors, For each selected combination of the first detection sensor and the second detection sensor, The position specifying means specifies the position of the object based on the detection results of the first detection sensor and the second detection sensor, The support means determines whether or not the position of the object is located within the support target area using the support target area set for the combination of the first detection sensor and the second detection sensor. The driving support device according to claim 1.

3. The first distance is a distance obtained by adding a distance obtained by correcting the distance between the first detection sensor and the second detection sensor according to the characteristics of the first detection sensor and the second detection sensor, and further considering a measurement error. The driving support device according to claim 1 or claim 2.

4. The second distance is a distance obtained by subtracting a distance considering a measurement error from the installation height of the first detection sensor with respect to the ground, or a distance that would be erroneously detected as the distance to an object by the first detection sensor itself receiving a detection wave transmitted in a state where water droplets are attached to the surface of the first detection sensor. The driving support device according to claim 1 or claim 2.

Images