Apparatus for detecting object approaching vehicle

An apparatus for detecting an object approaching a vehicle by performing image recognition processing on an image captured by a camera that is mounted on the vehicle to cover a predetermined area around the vehicle includes a signal receiver, a selector, and a detector. The signal receiver obtains a vehicle signal indicative of an operating condition of the vehicle. The selector selects a predetermined region of the captured image, according to the vehicle signal, as an object detection region. The detector detects the object approaching the vehicle by performing the image recognition processing on only the object detection region of the captured image.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on Japanese Patent Application No. 2011-148272 filed on Jul. 4, 2011, the disclosure of which is incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to an apparatus for detecting an object approaching a vehicle.

BACKGROUND

In a technique disclosed in JP-2001-239832A, an object approaching a vehicle is detected by performing image recognition processing on an image captured by a camera that is mounted on the vehicle to capture the area around the vehicle.

In the technique, the image recognition processing is applied on the entire region of the captured image. Therefore, high processing load is required when the image recognition processing is performed.

SUMMARY

In view of the above, it is an object of the present disclosure to provide a technique for reducing processing load required to perform image recognition processing to detect an object approaching a vehicle.

According to an aspect of the present disclosure, an apparatus for detecting an object approaching a vehicle by performing image recognition processing on an image captured by a camera that is mounted on the vehicle to cover a predetermined area around the vehicle includes a signal receiver, a selector, and a detector. The signal receiver obtains a vehicle signal indicative of an operating condition of the vehicle. The selector selects a predetermined region of the captured image, according to the vehicle signal, as an object detection region. The detector detects the object approaching the vehicle by performing the image recognition processing on only the object detection region of the captured image.

According to another aspect of the present disclosure, an apparatus for detecting an object approaching a vehicle by performing image recognition processing on an image captured by a camera that is mounted on the vehicle to cover a predetermined area around the vehicle includes a calculator, a selector, and a detector. The calculator calculates an inclination angle of a road around the vehicle with respect to the vehicle. The selector selects a predetermined region of the captured image, according to the inclination angle, as an object detection region. The detector detects the object approaching the vehicle by performing the image recognition processing on only the object detection region of the captured image. The object detection region corresponds to an area extending along the inclination angle of the road.

DETAILED DESCRIPTION

First Embodiment

A vehicle system according to a first embodiment of the present invention is described below with reference toFIG. 1. The vehicle system is mounted on a vehicle1and includes a display apparatus2, a vehicle signal receiver3, an electric sliding door4, an on-board camera5, and an electronic control unit (ECU)6.

The display apparatus2displays an image to an occupant of the vehicle1according to control of the ECU6. For example, an image captured by the on-board camera5can be displayed on the display apparatus2. The vehicle signal receiver3obtains a vehicle signal indicative of an operating condition of the vehicle1. Examples of the vehicle signal can include a shift position signal indicative of a shift position of the vehicle1, a speed signal indicative of a speed of the vehicle1, and a blinker signal indicative of operation conditions of left and right blinkers of the vehicle1. The electric sliding door4is a left backseat door of the vehicle1and opened and closed according to control of the ECU6.

The on-board camera5is a wide-angle camera and mounted in the back of the vehicle1to capture an image of the area behind the vehicle1. As shown inFIG. 1, the on-board camera5covers a capture area5awithin an angle of 180 degrees with respect to the back of the vehicle1. The image captured by the on-board camera5is inputted to the ECU6at regular intervals (e.g., sixty times per second) in frame.

The ECU6is a microcontroller having a CPU, RAM, and ROM. The CPU executes programs stored in the ROM by using the RAM as a working space so that the ECU6can perform various processes.

An operation of the vehicle system is described below with reference toFIG. 2.FIG. 2is a flow chart of a control process performed by the ECU6, for example, when a main power (e.g., ignition switch) of the vehicle1is turned ON. The control process starts at step110, where the ECU6obtains the vehicle signal from the vehicle signal receiver3. Then, the control process proceeds to step115, where the ECU6determines a type of the vehicle signal. If the vehicle signal is the shift position signal indicating that the shift position of the vehicle1is in a reverse position corresponding to “REVERSE” at step115, the control process proceeds to step125. If the vehicle signal is the speed signal indicating that the speed of the vehicle1is zero (or a lower than a predetermined minimum speed) corresponding to “STOP” at step115, the control process proceeds to step140.

If the vehicle signal is the blinker signal indicating that the left or right blinker of the vehicle1is ON (i.e., blinking) corresponding to “BLINKER-ON” at step115, the control process proceeds to step120. At step120, the ECU6determines which blinker is blinking. If the left blinker is blinking corresponding to “L” at step120, the control process proceeds to step155. In contrast, if the right blinker is blinking corresponding to “R” at step120, the control process proceeds to step170.

At step125, which is performed when the vehicle1moves back, the ECU6selects a first region of the image captured by the on-board camera5as an object detection region. The first region corresponds to a first area A of the capture area5a.

As shown inFIG. 3, the first area A is a band-like area having a predetermined width in a vertical direction of the vehicle1. The first area A is located at a predetermined distance from the back end of the vehicle1in a longitudinal direction of the vehicle1and extends from infinity to infinity in a lateral direction of the vehicle1.FIG. 4is a diagram illustrating one frame of an image20captured by the on-board camera5. In the captured image20shown inFIG. 4, the first region corresponding to the first area A is a region between a broken line21and a broken line22. That is, the first region corresponding to the first area A has neither a lower region (below the broken line22inFIG. 4) of the captured image20corresponding to an area near to the back end of the vehicle1and an upper region (above the broken line21inFIG. 4) of the captured image20corresponding to an area far from the back end of the vehicle1.

Then, the control process proceeds from step125to step130, where the ECU6performs image recognition processing on only the first region of each of multiple frames of the captured image20to detect an object approaching the vehicle1. In this case, a conventional detection method can be used to detect the object approaching the vehicle1based on the first region of the captured image20. For example, the ECU6can perform motion detection processing on the first region of the captured image20to detect whether an object moving in a direction approaching the vehicle1exists or not.

Then, the control process proceeds from step130to step135, where the ECU6performs a predetermined control action depending on the result of the image recognition processing performed at step130. For example, if an object approaching the vehicle1is detected at step130, the ECU6can cause an audio output device (not shown), such as a speaker, to output an audible alarm at step135that warns an occupant of the vehicle1that there is an object approaching the vehicle1. Further, at step135, the ECU6can display the captured image20on the display apparatus2. In this case, the approaching object can be highlighted in the captured image20. Furthermore, at step135, the ECU6can intervene and control, for example, an engine and/or a brake actuator of the vehicle1to limit movement of the vehicle1.

When the vehicle1moves back (in particular, when the vehicle1backs out of a parking lot), a road23is located slightly far from the back end of the vehicle1in the longitudinal direction of the vehicle1. In this case, there is a relatively high risk that the vehicle1collides with a vehicle running on the road23. According to the first embodiment, the first area A can cover the road23. Therefore, a vehicle running on the road23and approaching the vehicle1can be surely detected by performing the image recognition processing on only the first region of the captured image20corresponding to the first area A.

In contrast, if an object approaching the vehicle1is not detected at step130, the ECU6displays the captured image20on the display apparatus2at step135without performing any other of the above control actions. After step135, the control process returns to step110.

At step140, which is performed when the vehicle1is stopped, the ECU6selects a second region of the image captured by the on-board camera5as an object detection region. The second region corresponds to a second area B of the capture area5a.

As shown inFIG. 3, the second area B is a band-like area having a predetermined width in the lateral direction of the vehicle1. The second area B extends backward from the back end of the vehicle1to infinity in the longitudinal direction of the vehicle1.FIG. 5is a diagram illustrating one frame of an image30captured by the on-board camera5. In the captured image30shown inFIG. 5, the second region corresponding to the second area B is a region between a broken line31and a broken line32. That is, an area behind and on the left side of the vehicle1appears in the second region of the captured image30. A line35between the broken line31and the broken line32is a road edge line.

Then, the control process proceeds from step140to step145, where the ECU6performs image recognition processing on only the second region of each of multiple frames of the captured image30to detect an object approaching the vehicle1. The same detection method (e.g., motion detection processing) as used at step130can be used at step145.

Then, the control process proceeds from step145to step150, where the ECU6performs a predetermined control action depending on the result of the image recognition processing performed at step145. For example, if an object approaching the vehicle1is detected at step145, the ECU6can cause an audio output device (not shown), such as a speaker, to output an audible alarm at step150that warns an occupant of the vehicle1that there is an object approaching the vehicle1. Further, at step150, the ECU6can display the captured image30on the display apparatus2. In this case, the approaching object can be highlighted in the captured image30. Furthermore, at step150, the ECU6can intervene and control the electric sliding door4to prevent the electric sliding door4from being opened.

In countries, such as Japan, where vehicles keep to the left side of a road, when the vehicle1is stopped, an occupant in a rear seat of the vehicle1is likely to get off the vehicle1on the left side of the vehicle1. In this case, there is a relatively high risk that the occupant collides with an object approaching the vehicle1from behind and the left side of the vehicle1. According to the first embodiment, the second area B can cover the area behind and on the left side of the vehicle1. Therefore, an object approaching the vehicle1from behind and the left side of the vehicle1can be surely detected by performing the image recognition processing on only the second region of the captured image30corresponding to the second area B.

In contrast, if an object approaching the vehicle1is not detected at step145, the ECU6displays the captured image30on the display apparatus2at step150without performing any other of the above control actions. After step150, the control process returns to step110.

At step155, which is performed when the left blinker is ON, i.e., blinking, the ECU6selects the second region of the image captured by the on-board camera5as an object detection region. As mentioned above, the second region corresponds to the second area B of the capture area5a.

Then, the control process proceeds from step155to step160, where the ECU6performs image recognition processing on only the second region of each of multiple frames of the captured image30to detect an object approaching the vehicle1. The same detection method (e.g., motion detection processing) as used at step130can be used at step160.

Then, the control process proceeds from step160to step165, where the ECU6performs a predetermined control action depending on the result of the image recognition processing performed at step160. For example, if an object approaching the vehicle1is detected at step160, the ECU6can cause an audio output device (not shown), such as a speaker, to output an audible alarm at step165that warns an occupant of the vehicle1that there is an object approaching the vehicle1. Further, at step165, the ECU6can display the captured image30on the display apparatus2. In this case, the approaching object can be highlighted in the captured image30.

When the left blinker of the vehicle1is blinking, there is a relatively high risk that the vehicle1collides with an object approaching the vehicle1from behind the vehicle1and the left side of the vehicle1. According to the first embodiment, the second area B can cover the area behind and on the left side of the vehicle1. Therefore, an object approaching the vehicle1from behind and the left side of the vehicle1can be surely detected by performing the image recognition processing on only the second region of the captured image30corresponding to the second area B.

In contrast, if an object approaching the vehicle1is not detected at step160, the ECU6displays the captured image30on the display apparatus2at step165without performing any other of the above control actions. After step165, the control process returns to step110.

At step170, which is performed when the right blinker is ON, i.e., blinking, the ECU6selects a third region of the image captured by the on-board camera5as an object detection region. The third region corresponds to a third area C of the capture area5a.

As shown inFIG. 3, the third area C is a band-like area having a predetermined width in the lateral direction of the vehicle1. The third area C extends backward from the back end of the vehicle1to infinity in the longitudinal direction of the vehicle1. In the captured image30shown inFIG. 5, the third region corresponding to the third area C is a region between a broken line33and a broken line34. That is, an area behind and on the right side of the vehicle1appears in the third region of the captured image30. A line36between the broken line33and the broken line34is a road lane line such as a center line.

Then, the control process proceeds from step170to step175, where the ECU6performs image recognition processing on only the third region of each of multiple frames of the captured image30to detect an object approaching the vehicle1. The same detection method (e.g., motion detection processing) as used at step130can be used at step175.

Then, the control process proceeds from step175to step180, where the ECU6performs a predetermined control action depending on the result of the image recognition processing performed at step175. For example, if an object approaching the vehicle1is detected at step175, the ECU6can cause an audio output device (not shown), such as a speaker, to output an audible alarm at step180that warns an occupant of the vehicle1that there is an object approaching the vehicle1. Further, at step180, the ECU6can display the captured image30on the display apparatus2. In this case, the approaching object can be highlighted in the captured image30.

In contrast, if an object approaching the vehicle1is not detected at step175, the ECU6displays the captured image30on the display apparatus2at step180without performing any other of the above control actions. After step180, the control process returns to step110.

As described above, according to the first embodiment, the ECU6of the vehicle1selects a predetermined region of the image captured by the on-board camera5as an object detection region according to information contained in the vehicle signal received through the vehicle signal receiver3. Then, the ECU6tries detecting an object approaching the vehicle1by performing image recognition processing on only the object detection region of the captured image.

Since the image recognition processing is performed on only a limited region of the captured image, processing load required to detect an object approaching the vehicle1can be reduced as compared to when the image recognition processing is performed on the entire region of the captured image. Further, the object detection region is selected according to an operating condition of the vehicle1. In such an approach, although the image recognition processing is performed on only the object detection region, an object dangerous to the vehicle1can be suitably detected.

Second Embodiment

A second embodiment of the present disclosure is described below with reference toFIGS. 6 and 7. A difference of the second embodiment from the first embodiment is that the ECU6performs a control process shown inFIG. 6instead of the control process shown inFIG. 2.

As can be seen by comparingFIGS. 2 and 6, additional steps105and123are included in the second embodiment. Step105is performed before step110, and step123is performed before step125. At step105, the ECU6detects an inclination angle θ of a road around (e.g., behind) the vehicle1with respect to the lateral direction of the vehicle1. At step123, the ECU6determines the first area A according to the detected inclination angle θ.

A method of detecting the inclination angle θ at step105is described in detail below. In an example shown inFIG. 7, a longitudinal direction48of the road is inclined at an angle θ with respect to a lateral direction47of a parking lot sectioned by lines51-54. When the vehicle1is stopped and parked in the parking lot, the road behind the vehicle1is inclined at the angle θ with respect to the lateral direction of the vehicle1.

In this case, at step105, the ECU6determines the direction of the road based on the image captured by the on-board camera5. For example, the ECU6can detect a direction, in which white lines (or border lines, ruts)41-46on the road extend, by performing conventional image processing, including distortion correction, binarization, and Hough transform, on the captured image. The ECU6determines the detected direction of the white lines41-46as the direction of the road. Then, the ECU6calculates an angle θ of the determined direction of the road with respect to the lateral direction of the vehicle1. The calculated angle θ is the inclination angle θ.

Next, step123is described in detail. When the vehicle signal is the shift position signal indicating that the shift position of the vehicle1is in the reverse position corresponding to “REVERSE” at step115, the control process proceeds to step123. At step123, the ECU6determines the first area A according to the inclination angle .theta. calculated at step105.

Specifically, as shown inFIG. 7, the first area A is the sum of an area61and an area62. The area61is a band-like area having a predetermined width. The area61extends parallel to the direction of the road from infinity to an end of the capture area of the on-board camera5. The area62extends from an end of the area61to infinity in the lateral direction of the vehicle1on the right side of the vehicle1along the end of the capture area of the on-board camera5.

Then, at step125, the ECU6selects the first region of the captured image, corresponding to the first area A determined at step123, as an object detection region. Then, at step130, the ECU6performs image recognition processing on only the first region to detect an object approaching the vehicle1. Then, at step135, the ECU6performs a predetermined control action depending on the result of the image recognition processing performed at step130, as mentioned in the first embodiment.

As described above, according to the second embodiment, the ECU6of the vehicle1detects the inclination angle .theta. of the road around the vehicle1with respect to the vehicle1. Then, the ECU6determines the first area A according to the detected inclination angle .theta. so that the first area A can cover an area extending along the road. In such an approach, although the image recognition processing is performed on only the object detection region, an object dangerous to the vehicle1can be suitably detected.

The correspondence between the terms used in the embodiments and claims is as follows. The ECU6can serve as a signal receiver in claims by performing step110. The ECU6can serve as a selector in claims by performing steps115,120,123,125,140,155, and170. The ECU6can serve as a calculator in claims by performing step105.

Modifications

In the embodiments, the on-board camera5is configured to capture an image of the area behind the vehicle1. Alternatively, the on-board camera5can be configured to capture an image of the area ahead of or all around the vehicle1. Even in such a case, the same advantages as the embodiments can be obtained by selecting a predetermined region of the image captured by the on-board camera5as an object detection region according to information contained in the vehicle signal received through the vehicle signal receiver3and by detecting an object approaching the vehicle1by performing image recognition processing on only the object detection region of the captured image.

In the embodiments, the electric sliding door4is a left backseat door of the vehicle1. Alternatively, the electric sliding door4can be a right backseat door of the vehicle1. That is, in countries, such as the United States, where vehicles keep to the right side of a road, when the vehicle1is stopped, an occupant in a rear seat of the vehicle1is likely to get off the vehicle1on the right side of the vehicle1. In such countries, there is a relatively high risk that the occupant collides with an object approaching the vehicle1from behind and the right side of the vehicle1. Therefore, at step140inFIGS. 2 and 6, the ECU6selects the third region of the captured image corresponding to the third area C of the capture area5a. In this case, inFIG. 5, the line31can represent the road lane line, and the line36can represent the road edge line.