The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:
Referring first to
The in-vehicle camera 12 may be a CCD camera made up of image pickup elements such as a CCD. The in-vehicle camera 12 is located above a mounting position HdLt of the light device (headlamp) 30 such as vehicle headlamps (not shown), and mounted, for example, in the vicinity of a rear-view mirror within a vehicle compartment.
The in-vehicle camera 12 continuously picks up an image of a road in front of the vehicle as shown in
That is, as shown in
The image processing ECU 14 includes a computer having a CPU, a ROM, and an RAM, and temporarily stores data of an image which is continuously picked up by the in-vehicle camera 12 for a given period of time in the RAM. The CPU executes a visibility condition determining processing shown in
The yaw rate sensor 16 detects a yaw rate of the vehicle, and the steering sensor 18 detects a steering angle of the steering. The vehicle speed sensor 22 detects a travel speed of the vehicle.
The drive assist control ECU 26 executes various controls of an off-lane alarm system that generates an alarm when the vehicle tends to cross a white lane marking (lane line) and deviate from the travel lane, and of a lane keeping assist system that makes the steering wheel generate a given steering torque so as to keep the vehicle within the lane.
The light control ECU 28 acquires a headlamp lighting switch signal through the in-vehicle LAN 24, and controls the on/off of the headlamps according to the headbeam lighting switch signal. The light control ECU 28 controls, as an adaptive front lighting system, the beam distribution of the headlamps according to the travel speed, the yaw rate, or the steering angle.
The image processing ECU 14 temporarily stores the data of the image from the in-vehicle camera 12, and subjects the image to given processing to execute lane line recognition processing for recognizing the lane line of the vehicle. The positional information on the lane line which is recognized by the lane line recognition processing is outputted to the drive assist control ECU 26.
The image processing ECU 14 according to this embodiment executes the visibility condition determination processing for determining the visibility condition outside the vehicle during traveling at night by using the in-vehicle camera 12 used for recognition of the lane line. In the visibility condition determination processing, the visibility condition outside of the vehicle is determined based on the brightness of the non-irradiated area Aoff shown in
This is because a difference in the brightness occurs according to the visibility condition outside of the vehicle when the headlamps are turned on. More specifically, for example, if the visibility condition is excellent, because beams are not directly irradiated to the non-irradiated area Aoff from the headlamps, the brightness is frequently low as a whole.
However, for example, when the occurrence of fog causes the poor visibility condition, the beams irradiated from the headlamps are scattered by fog particles although the beams from the headlamps are not directly irradiated to the non-irradiated area Aoff. As a result, as shown in
As described above, the vehicle visibility condition determining device 10 takes into consideration the fact that the brightness of the non-irradiated area Aoff is different between a case where the visibility condition is excellent (no fog for instance) and a case where the visibility condition is poor (fog, for instance). Hereinafter, the non-irradiated area is referred to as a scattered beam detection area Aoff.
It is preferable that the in-vehicle camera 12 picks up an image including the transmission space closest to the headlamps in the imaging area among the transmission spaces through which the beams irradiated from the headlamps are transmitted, as shown in
The image processing ECU 14 executes a visibility condition determining processing as shown in
As shown in
The lamp lighting determination processing of S100 will be described with reference to a flowchart shown in
In S102, it is checked whether the travel speed of the vehicle is equal to or higher than a given speed indicative of vehicle traveling. When the determination is YES in S102, processing is advanced to S103. On the other hand, when the determination is NO, processing is advanced to S104.
In S103, “1” (determination execution) is substituted for a visibility condition determination flag fg to complete this processing. On the other hand, in S104, “0” (determination prohibition) is substituted for the visibility condition determination flag fg to complete this processing.
As described above, in the lamp lighting determination processing S100, when the travel speed of the vehicle is equal to or higher than the given speed, the visibility condition determination flag fg is set as “1” (determination execution) for the following reason. That is, in the case where the background of the transmission space on the image is a road, when the travel speed of the vehicle is extremely low (about several km/hour), an object on the road (for example, lane line) can be imaged in focus. As a result, an influence of the scattered beam detection area Aoff on the brightness is large. However, when the travel speed of the vehicle is higher than the extremely low speed, the object on the road is imaged in the blur. As a result, the background of the transmission space on the image becomes substantially even, and the influence of the scattered beam detection area Aoff on the brightness is small.
The scattered beam detection area image extraction processing of S200 is shown in
On the other hand, when the determination is YES in S201, the image data of the scattered beam detection area Aoff is extracted in S202. The position of the scattered beam detection area Aoff on the image is set in advance. In this embodiment, as shown in
In S300 of
For example, when the visibility condition is excellent (no fog), because the beams are not directly irradiated to the scattered beam detection area Aoff from the headlamps, the luminance values are frequently low as a whole, but there is a tendency to gradually increase the luminance values from the outside toward the inside within the image (positive luminance gradient).
On the other hand, for example, when the visibility is poor due to fog, the beams are not directly irradiated to the scattered beam detection area Aoff from the headlamps. However, because the beams irradiated from the headlamps are scattered by the fog particles, the luminance values of the scattered beam detection area Aoff are frequently high as a whole, which is attributable to the scattered beams. However, there is a tendency to gradually decrease the luminance values from the outside toward the inside within the image (negative luminance gradient).
Therefore, as shown in
When an abnormal value is contained in the luminance values of the respective pixels g1 included in the scattered beam detection area Aoff, a linear characteristic shown in
In the visibility condition determination processing, the probability when the calculated luminance gradient is applied to the fog probability map shown in
The drive assist control ECU 26 that is connected to the in-vehicle LAN 24 executes control based on the fog probability information. For example, when the probability of fog is high, the drive assist control ECU 26 executes the control after the degree of reliability of the lane line recognition result is decreased by the lane departure alarm or the lane keeping assist. The light control ECU 28 executes control so as to change over to low beams, or executes control so as to automatically turn on fog lamps when the headlamps are high beams when the probability of fog is high.
In a vehicle on which an inter-vehicle distance control device that holds an inter-vehicle distance to a leading vehicle to a target inter-vehicle distance, for example, when the probability of fog is high, the inter-vehicle distance control device is capable of changing the target inter-vehicle distance to be longer than normal. Alternatively, for example, when the probability of fog is high, the inter-vehicle distance control device can limit the top speed of the vehicle.
As described above, the vehicle visibility condition determining device 10 according to this embodiment is capable of determining the visibility condition outside of the vehicle by the single subject vehicle because the headlamps that are mounted on the vehicle and the image that are up by the in-vehicle camera 12 are used.
The first embodiment may be modified as follows.
For example, in this embodiment, as shown in the lamp lighting determination processing of
That is, when the fog lamps are being turned off, and only the headlamps are turned on, the background of the non-irradiated area is dark, and the beams irradiated from the headlamps are irradiated to a narrow area. In this case, the brightness of the non-irradiated area is remarkably changed between the excellent visibility condition and the poor visibility condition, which is therefore in a state that is suitable for the determination of the visibility condition.
Accordingly, according to a first modification, in a state where the headlamps of the vehicle are turned on, and the fog lamps of the vehicle are turned off, it is determined that the state is suitable for the determination of the visibility condition. The degree of reliability of the determination result of the visibility condition when it is determined that the state is suitable for the determination of the visibility condition is high as compared with the determination result of the visibility condition which is conducted by the visibility condition determination processing when it is determined that the state is unsuitable for the determination of the visibility condition.
More specifically, the lamp lighting determination processing shown in
Then, in the visibility condition determination processing of Step 400 in
With the above processing, a difference may occur in the degree of reliability of the determination result of the visibility condition depending on whether the state being suitable for the determination of the visibility condition or not. As a result, when the control device that is different in the operation start timing according to a precision in the determination of the visibility condition is mounted on the vehicle, the response of the control device can be enhanced.
When the headlamps are turned on as the high beams, since the light beams from the headlamps are sufficiently strong, the state is more suitable for the determination of the visibility condition than the state when the headlamps are turned on as the low beams.
In the first embodiment, the visibility condition is determined from the luminance gradient of the respective pixels g1 that are included in the scattered beam detection area Aoff. However, as described above, when the visibility condition is excellent, the luminance values of the scattered beam detection area Aoff are frequently low as a whole. When the visibility condition is poor, the luminance values of the scattered beam detection area Aoff are frequently high as a whole.
Accordingly, according to a second modification, the visibility condition may be determined based on the brightness of one or more pixels that are included in the scattered beam detection area Aoff. For example, when the brightness of one or more pixels that are included in the scattered beam detection area Aoff is high, it is determined that the visibility condition is poor. When the brightness of one or more pixels that are included in the scattered beam detection area Aoff is low, it is determined that the visibility condition is excellent. As a result, a load of processing for determining the visibility condition is reduced.
Also, according to a third modification, the in-vehicle camera 12 is preferably mounted on the vehicle so that the background of the transmission space in the image becomes a chassis of the vehicle. This is because when the background of the transmission space in the image is even, an influence of the scattered beam detection area Aoff on the luminance value is small.
Also, in a night view device, an infrared ray is irradiated toward the front of the vehicle at the time of traveling in the night to display a pedestrian, another vehicle, an obstacle or a road status which is difficult to view inside or outside of the irradiated area of the headlamps. The in-vehicle camera having an image pickup device that senses the infrared rays may be employed. Therefore, according to a fourth modification, in the vehicle on which the night view is mounted, since both the lighting device that irradiates the infrared rays and the in-vehicle camera having the image pickup device that senses the infrared rays are mounted on the vehicle, it is possible to determine the visibility condition outside of the vehicle by using those existing devices without mounting an additional device.
When the in-vehicle camera that images the backside of the vehicle is located above positions at which a car registration plate lamp (license plate lamp) of the vehicle is installed, it is possible according to a fifth modification to determine the visibility condition outside of the vehicle based on the image that are picked up by the in-vehicle camera.
A vehicle visibility condition determining device 10 according to a second embodiment is different from that of the first embodiment in that a state that is suitable for the determination of the visibility condition is positively created by changing the light quantity or the optical axis direction of the headlamps or the fog lamps to determine the visibility condition.
The lamp lighting state change processing S10 is shown in
In S12, it is checked whether the vehicle state corresponds to a given state or not. In this example, the given state is directed to vehicle states when a subject vehicle or a leading vehicle that exists in front of the subject vehicle stops, after the vehicle starts moving, after the acceleration or deceleration of the vehicle is completed, and after lighting of turn signal lamps of the vehicle is terminated. It is checked whether the vehicle state corresponds to at least any one of those vehicle states or not. When the determination is YES in S12, the operating state of the headlamps or the fog lamps are changed in S13. When the determination is NO, this processing is completed.
As a result, the operating state of the headlamps or the fog lamps is changed at a timing, for example, when a subject vehicle or a leading vehicle that exists in front of the subject vehicle stops, after the vehicle starts moving, after the acceleration or deceleration of the vehicle is completed, and after lighting of turn signal lamps of the vehicle is terminated. As a result, it is possible to change turning on/off, the light quantity, and the optical axis direction of beams irradiated from the headlamps or the fog lamps at a timing when driver's attention is called to the front of the vehicle and at a timing when an influence on the driving operation is relatively small.
In S13, the operating state of the headlamps or the fog lamps is changed. That is, as described above, turning on/off, the light quantity, and the optical axis direction of beams irradiated from the headlamps or the fog lamps are changed. When the state is improper for the determination of the visibility condition, the operating state of the headlamps or the fog lamps is changed. As a result, even when the state is improper for the determination of the visibility condition, the state can be positively changed to a state that is suitable for the determination of the visibility condition. In order to suppress an influence on the driving operation as much as possible, it is desirable to temporarily change turning on/off, the light quantity, and the optical axis direction of beams irradiated from the headlamps or the fog lamps.
In S13, the low beams of the headlamps or the fog lamps are changed from an on state to an off state (or from the off state to the on state), the light quantity of the low beams of the headlamps or the fog lamps is adjusted, the optical axis direction of the low beams of the headlamps or the fog lamps is changed from the left (right) direction of the vehicle to the right (left) direction, or from the upper (lower) direction of the vehicle to the lower (upper) direction.
In the visibility state determination processing in S400 of
The reason is stated below. That is, when the visibility condition is excellent, there is a small change in the brightness of the non-irradiated area, which is attributable to the change in turning on/off, the light quantity, and the optical axis direction of beams irradiated from the headlamps or the fog lamps. On the other hand, when the visibility condition is poor, there is a remarkable change in the brightness of the non-irradiated area, which is attributable to the change in turning on/off, the light quantity, and the optical axis direction of beams irradiated from the headlamps or the fog lamps.
In S400, when a difference between the brightness of the non-irradiated area before the operating state of the headlamps or the fog lamps is changed and the brightness of the non-irradiated area after the operating state of the headlamps or the fog lamps is changed reaches a given brightness difference or more, it is determined that the visibility condition is poor.
As described above, when the visibility condition is excellent, because the irradiated beams are not directly irradiated to the non-irradiated area, the brightness is frequently low. In addition, there is a small change in the brightness of the non-irradiated area, which is attributable to the change in turning on/off, the light quantity, and the optical axis direction of the low beams of the headlamps or the fog lamps.
On the contrary, when the visibility condition is poor, because the scattered beams are scattered in the non-irradiated area, the brightness is frequently high. In addition, there is a remarkable change in the brightness of the non-irradiated area, which is attributable to the change in turning on/off, the light quantity, and the optical axis direction of the low beams of the headlamps or the fog lamps. Accordingly, when there is the given brightness difference or more, it is determined that the visibility condition is poor. As a result, it is possible to improve a precision in the determination of the visibility condition.
The present invention can be implemented with further modifications.
Number | Date | Country | Kind |
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2006-184805 | Jul 2006 | JP | national |
2006-259439 | Sep 2006 | JP | national |