JP2007131092A - Obstacle sensing device and vehicle braking system with obstacle sensing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an obstacle sensing device capable of sensing certainly any obstacle existing in proximity even in the situation where it is difficult to make sure the image of the obstacle. <P>SOLUTION: The obstacle sensing device is equipped with a first sensing means 2 to emit searching waves to the area surrounding a vehicle for sensing object on the basis of the reflected waves from the object, a second sensing means 3 to sense the shape of the object (information about the height, width, etc.) on the basis of the image for the area around the vehicle, an obstacle judging means 4 to judge whether the object is an obstacle on the basis of the first sensing signal given by the first sensing means and the second sensing signal given by the second sensing means, wherein the obstacle judging means 4 senses the object as obstacle irrespective of the result of the second sensing signal in case an object whose distance from the vehicle is acknowledged according to the first sensing signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an obstacle detection device that is mounted on a vehicle and detects surrounding obstacles.

  In recent years, vehicles equipped with obstacle detection devices have been provided. Such an obstacle detection device can detect obstacles around the vehicle, so that it is not only a driving support device effective for the driver, but also a device that protects humans when the detected obstacle is a human being. Also works. As an obstacle detection apparatus, an apparatus including a radar sensor (also simply referred to as a radar or a distance measurement sensor) that detects an object using a search wave such as a laser beam or a millimeter wave is known. However, the radar sensor can detect the distance and direction from the vehicle to the object, but cannot obtain the shape of the object. For this reason, it may be difficult to determine whether or not the detected object is actually an obstacle.

  Thus, for example, Patent Document 1 proposes an obstacle detection device (object type determination device) that can be used to specify the height of an obstacle ahead of the vehicle using a camera. This obstacle detection device can not only detect the distance and direction to the object in front of the vehicle, but also check the height. Therefore, according to the apparatus of Patent Document 1, it is possible to determine whether or not the detected object hinders the traveling of the vehicle.

JP 2003-44995 A

  As described above, the obstacle detection device not only functions as a driving support device for the driver, but also functions as a device for protecting humans. For example, when a vehicle approaches a pedestrian without the driver's knowledge, the pedestrian can be detected by the obstacle detection device. Based on the result of the obstacle detection device, an emergency warning can be given to the driver to alert him or the vehicle can be forced to brake.

  However, the camera of the obstacle detection device is easily affected by the external environment. For example, it is difficult to image an object in dense fog, rainy weather, darkness, or the like. Also, there are cases where an obstacle cannot be detected accurately if the lens on the front of the camera is covered with mud. Here, since the apparatus of Patent Document 1 is configured to always distinguish an object using an image from a camera, there is a possibility that an obstacle cannot be reliably detected. Moreover, although the apparatus of patent document 1 considers only detecting the obstruction ahead of a vehicle, since the driver | operator has also visually observed about the advance direction of a vehicle, it is easy to confirm an obstruction relatively. On the other hand, there is a fact that it is difficult to confirm an obstacle when the vehicle is moving backward, but the device of Patent Document 1 does not consider such points.

  Therefore, the present invention has been made in view of the above-described conventional problems, and even when it is difficult to confirm an image of an obstacle, if there is an approaching obstacle, this is reliably detected. It is an object to provide an obstacle detection device that can be used.

  The object is to detect the object on the basis of an image obtained by imaging the periphery of the vehicle, and to detect the object on the basis of the reflected wave from the object by emitting a search wave around the vehicle; Obstacle judging means for judging whether or not an object around the vehicle is an obstacle based on the first detection signal from the first detection means and the second detection signal from the second detection means. The obstacle determination device comprises the second detection signal when the obstacle determination unit confirms an object whose distance from the vehicle is equal to or less than a predetermined distance in the first detection signal. Regardless of whether the object is detected as an obstacle, the object can be achieved by an obstacle detection device.

  According to the present invention, when there is an object approaching the vehicle such that the distance from the vehicle is equal to or less than a predetermined distance, the object is based on the first detection signal regardless of the result of the second detection signal. Is detected as an obstacle. Therefore, when the obstacle is a human, protection can be achieved, and when the obstacle is a structure or the like, vehicle damage can be prevented or reduced.

  The second detection means preferably detects the shape of the object. Since the shape of the object includes at least information on the height and width of the object, the obstacle can be detected more reliably by using these pieces of information.

  In addition, when the obstacle determination unit further confirms an object at a position where the distance from the vehicle is larger than a predetermined distance by the first detection signal, the height of the object is determined by the second detection signal. It is preferable to detect the object as an obstacle when it is confirmed that the height is equal to or higher than the predetermined height. In this way, it is possible to determine whether or not an object at a distance is an obstacle, and then deal with it with a margin.

  More preferably, the first detection means emits the search wave from a predetermined height. If comprised in this way, it will suppress that a search wave reflects on the ground, and can detect an obstruction more reliably.

  In addition, if a vehicle braking system that includes the obstacle detection device and brakes the vehicle based on the detection result of the obstacle detection device is formed, the vehicle can be stopped reliably.

  According to the present invention, it is possible to provide an obstacle detection device that can reliably detect an obstacle that is approaching even if it is difficult to confirm an image of the obstacle.

  Hereinafter, an obstacle detection device according to an embodiment of the present invention will be described with reference to the drawings. The obstacle detection device of the present embodiment is a device that detects the obstacle by checking the surroundings of the vehicle, but if the vehicle is forcibly stopped using this detection result, the obstacle detection device Even if a collision is avoided or a collision occurs, damage can be reduced. Therefore, in the embodiment shown below, the vehicle braking system using the obstacle detection device of the embodiment is also referred to.

  FIG. 1 is a block diagram showing a configuration of an obstacle detection apparatus 1 in a state where it is applied to a vehicle. FIG. 2 is a diagram schematically showing the relationship between the vehicle CR on which the obstacle detection apparatus 1 is mounted and the obstacle BL.

  The obstacle detection apparatus 1 includes a radar sensor 2, an image sensor 3, and an electronic control unit 4 (Electronic Control Unit: hereinafter referred to as ECU 4) that controls these and serves as an obstacle determination unit. The radar sensor 2 detects the azimuth and distance of an object existing around the vehicle as first detection means. The radar sensor 2 detects an object using search waves such as millimeter waves, laser light, and sound waves. The radar sensor 2 emits a search wave and receives a reflected wave reflected by an object. More preferably, the radar sensor 2 detects an object by scanning a search wave in a substantially horizontal direction from a predetermined height with reference to the ground on which the vehicle CR travels. Search waves such as millimeter waves and laser light have the property of reflecting off the ground. However, by scanning the search wave in a substantially horizontal direction with respect to the ground in this way, the object can be reliably detected while suppressing the influence of reflection by the ground. A detection signal (first detection signal) of the radar sensor 2 is supplied to the ECU 4.

  The image sensor 3 detects the shape (information on height, width, etc.) of an object (obstacle) based on an image obtained by capturing the periphery of the vehicle as second detection means. The image sensor 3 can be an electronic camera that images an object using an image sensor such as a CCD or CMOS. An object may be imaged with a configuration in which the camera is moved as a single eye, or a plurality of cameras may be arranged to image an object in a stereo manner. Although it is difficult for the radar sensor 2 to detect the height, width, etc. of the object, the image sensor 3 can detect the shape of the object and specify the height, width, etc. of the object. A detection signal (second detection signal) from the image sensor 3 is also supplied to the ECU 4.

  The radar sensor 2 and the image sensor 3 may be appropriately installed on a bumper, a door, a pillar, or the like of the vehicle so as to detect an object existing in the front, side, or rear of the vehicle as necessary. As shown in FIG. 2, the obstacle detection apparatus 1 of the present embodiment is provided with a radar sensor 2 and an image sensor 3 so as to detect an object existing behind the vehicle CR. In general, it is harder to detect an obstacle when the vehicle is moving backward than when the vehicle is moving forward. In particular, in a situation where the field of view of the image sensor 3 is poor, it becomes difficult to detect an obstacle. Assuming such a situation, the present embodiment will describe a case where the obstacle detection apparatus 1 detects a rear obstacle.

  The ECU 4 controls the driving of the radar sensor 2 and the image sensor 3. Further, the ECU 4 determines whether an object behind the vehicle CR is an obstacle based on the first detection signal from the radar sensor 2 and the second detection signal from the image sensor 3. The ECU 4 is connected via a bus 7 to a ROM 5 that stores a series of programs for detecting obstacles and data used for the obstacles, and a RAM 6 that provides a processing area. Although the ECU 4 may be prepared exclusively for the obstacle detection device 1, the configuration of the obstacle detection device 1 can be simplified by diverting the vehicle CR side ECU.

  In addition, when the ECU functions as an obstacle determination unit and detects an obstacle, it is preferable that the vehicle CR side take measures to avoid a collision by using the detection result. Therefore, in FIG. 1, as a more preferable form, a configuration in which a vehicle braking system that automatically brakes the vehicle CR when there is an obstacle BL in which the ECU 4 approaches the vehicle CR is illustrated.

  A configuration related to the vehicle braking system will be briefly described. The vehicle information 11 on the vehicle CR side is supplied to the ECU 4. Such vehicle information 11 is, for example, the vehicle speed, steering angle, etc. of the vehicle CR. When the ECU 4 detects an obstacle to avoid a collision, the ECU 4 further checks the state of the vehicle CR side and operates the brake 12 when it is necessary to stop the vehicle CR urgently. At the same time, a predetermined warning 13 is given. Such a warning may display a predetermined character on a display equipped in the vehicle CR, or may output a warning sound or sound from a speaker.

  Further, the obstacle detection apparatus 1 is configured to detect an object (obstacle) approaching the rear of the vehicle CR with high accuracy. This point will be described with reference to FIG. FIG. 3 is a diagram collectively showing the distance from the vehicle to the object and how the ECU 4 detects the object based on the detection signals from the radar sensor 2 and the image sensor 3 according to the distance. In particular, FIG. 3 summarizes a collision that can be avoided when the detected obstacle is a human being.

  Cases 0 to 3 shown in FIG. 3 are classified according to the distance from the vehicle CR to the object (obstacle). It is assumed that the case 0 has an object at a position closest to the vehicle, and the case 3 has an object at a position farthest from the vehicle.

  In cases 2 and 3, the distance to the object is sufficiently long, and the object detected by the radar sensor 2 is confirmed by the detection signal from the image sensor 3 to be a moving object or a stationary object. Judgment. As a result, the object is judged to be “pretty human” or “human”, for example. Such a determination may be set so that the ECU 4 performs the determination. Case 1 is a case where the object is very close to the vehicle. In this case, the ECU 4 determines the information about the height and width from the image sensor 3. For example, the ECU 4 compares the standard human width with the width of the object, and determines that the person is not human if the object width is too wide for a human.

  Note that C1, C2, and C3 shown in FIG. 3 are predetermined constants for specifying the object. The constant C1 relates to the distance, and is set at a position close to the vehicle. For example, the constant C1 is changed in relation to the speed of the vehicle, and a short distance is assumed such that a margin (distance to an obstacle) becomes 0 cm when braking is performed at that speed. The distance according to the constant C1 is, for example, 0.5 to 2 m from the vehicle. The constant C2 relates to the height and is set assuming the height of a person. The constant C3 relates to the width, and is set assuming a human width. Therefore, for example, with reference to the constant C2, the ECU 4 determines that the object is not human when the detected object is too high to be assumed to be human or when the detected object is low. The same applies to the constant C3 regarding the width.

  Here, in case 0, the detected object is present at a position equal to or smaller than the distance C1 from the vehicle, that is, the object detected by the radar sensor 2 is very close to the vehicle, and the vehicle is braked at this point. However, it is unknown whether or not the collision can be avoided. However, when the detected object is a human, the vehicle can be protected by urgently braking to reduce damage. In addition, if the structure is a structure such as a support, damage to the vehicle itself can be reduced. From such a point, when it is detected that there is an obstacle at a position very close to the vehicle, it can be said that braking the vehicle quickly is an effective countermeasure.

  The obstacle detection device 1 according to the present embodiment has a configuration for accurately detecting an obstacle in a situation corresponding to case 0. This point will be further described. As described above, by using the detection signal (second detection signal) from the image sensor 3 together with the detection signal (first detection signal) from the radar sensor 2, the shape of the obstacle (height, width information, etc.) ). However, the image sensor 3 is easily affected by external factors such as fog and lens contamination, and there are cases where an obstacle cannot be accurately identified. Moreover, if the ECU 4 always detects the obstacle in consideration of the detection signal from the image sensor 3, the processing load increases and processing time is required. In particular, as in case 0, when it is desired to detect the presence or absence of an obstacle quickly and accurately, checking the detection signal from the image sensor 3 may cause a delay in judgment or an error.

  Therefore, when the radar sensor 2 detects an object in the situation corresponding to the case 0, the ECU 4 detects the object as an obstacle regardless of the result of the detection signal (second detection signal) of the image sensor 3. . As described above, the search wave emitted from the radar sensor 2 has the property of being easily reflected on a road or the like, but this point is hardly considered when detecting an object approaching the vehicle CR. It's okay. Further, the radar sensor 2 is less susceptible to external factors than the image sensor 3 and can therefore detect an object at the approach position with high accuracy. In particular, when a search wave such as a millimeter wave emitted from the radar sensor 2 is scanned horizontally as in this embodiment, the influence of reflection by the ground is further reduced. It can be determined that there is an object (obstacle) at the approached position.

  An area AR shown in FIG. 2 illustrates a detection area by the radar sensor 2. Even if the object is close to the vehicle CR, the object having an extremely low height is set so as not to be detected. With this setting, a low curb or the like cannot be detected, but a person who needs reliable protection can be detected reliably.

  FIG. 4 is a flowchart showing an example of an obstacle detection executed by the ECU 4 and a routine for braking the vehicle using the result. This routine is activated when, for example, the ignition key of the vehicle is turned on.

  The ECU 4 controls each of the radar sensor 2 and the image sensor 3 to search for an object behind the vehicle. As described above, the azimuth and distance of the object are detected by the radar sensor 2 (S11), and the detection signal is supplied to the ECU 4. The shape of the object is detected by the image sensor 3 (S12), and the detection signal is supplied to the ECU 4.

  Here, the ECU 4 checks whether or not the distance CA (actual distance) from the detection signal from the radar sensor 2 to the object is shorter than the predetermined distance C1 (S13). When the detected distance CA is larger than the predetermined distance C1 (see FIG. 3), there is a margin in the distance for avoiding because the obstacle is far away. Therefore, the ECU 4 also considers the detection signal (second detection signal) from the image sensor 3 and detects the object as an obstacle when it is confirmed that the height of the object is equal to or higher than the predetermined height (S15). Then, the ECU 4 executes brake control with a margin for avoiding a collision with an obstacle (S16), and ends the processing by this routine.

It should be noted that when the brake control is executed in step 16 described above, the brake braking may be started based on the following equation.
LT = {− (V0 ² ) / (2 × A0)} + L0
Here, LT: braking start distance (m), V0: current vehicle speed (m / s), A0: acceleration (m / s ² ), and L0 is a margin distance (m). If the current distance of the vehicle falls below the braking start distance LT, the ECU 4 may be set to start braking.

  On the other hand, when the detected distance CA is smaller than the predetermined distance C1 (S13), there is almost no margin for avoiding the obstacle, so that the detection by the radar sensor 2 is performed regardless of the detection signal by the image sensor 3. When an object is detected based on the signal (S14), emergency brake control is executed (S17). As a result, the vehicle CR is stopped and the processing according to this routine is terminated. By handling in this way, when the detected obstacle is a human, it can be surely protected, and when the obstacle is a structure, damage to the vehicle is prevented or reduced. be able to.

  As described above, according to the obstacle detection apparatus 1 of the present embodiment, when an object is present at a position approached when the vehicle moves backward, the object is detected based on the detection signal of the radar sensor 2, so that it is accurate. And this object can be detected as an obstacle efficiently. Therefore, protection can be achieved when the obstacle is a human being. And, as shown in the embodiment, by adopting a vehicle braking system configured to automatically brake the vehicle based on the detection result, avoiding a collision with an obstacle, even when a collision occurs Damage can be reduced.

  Although the said Example has illustrated the case where the object behind a vehicle is detected as embodiment which uses this invention more effectively, it is not limited to this. The radar sensor 2 and the image sensor 3 may be arranged so that an object in the front or side of the vehicle or in all directions can be detected, and detection may be performed by the ECU 4.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims. It can be changed.

It is the block diagram which showed the structure of the obstacle detection apparatus of the state applied to the vehicle. It is the figure which showed typically the relationship between the vehicle in which an obstruction detection apparatus is mounted, and an obstruction. It is the figure which showed collectively a mode that ECU detected an object based on the distance from a vehicle to an object, and the detection signal from a radar sensor and an image sensor according to this distance. It is the flowchart which showed an example of the routine which brakes a vehicle using the obstacle detection performed by ECU of an obstacle detection apparatus, and this result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Obstacle detection apparatus 2 Radar sensor (1st detection means)
3 Image sensor (second detection means)
4 ECU (obstacle determination means)
11 Vehicle information 12 Brake 13 Warning CR Vehicle BL Obstacle

Claims (5)

First detection means for emitting a search wave around the vehicle and detecting the object based on a reflected wave from the object, second detection means for detecting an object based on an image obtained by imaging the periphery of the vehicle, and the first An obstacle comprising obstacle judging means for judging whether or not an object around the vehicle is an obstacle based on the first detection signal from the detection means and the second detection signal from the second detection means. An object detection device comprising:
The obstacle determining means detects the object as an obstacle regardless of the result of the second detection signal when the object having a distance from the vehicle of a predetermined distance or less is confirmed by the first detection signal. An obstacle detection device characterized by that. The obstacle detection apparatus according to claim 1, wherein the second detection unit detects a shape of the object. When the obstacle determination unit further confirms an object at a position where the distance from the vehicle is greater than a predetermined distance by the first detection signal, the height of the object is determined to be a predetermined height by the second detection signal. 3. The obstacle detection apparatus according to claim 1, wherein the object is detected as an obstacle when it is confirmed that the distance is equal to or greater than the predetermined value. The obstacle detection device according to claim 1, wherein the first detection unit emits the search wave from a predetermined height. A vehicle braking system comprising the obstacle detection device according to claim 1, wherein the vehicle is braked based on a detection result of the obstacle detection device.

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