JP3431498B2 - Pedestrian detection system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pedestrian detection system for detecting a pedestrian to prevent a pedestrian accident.

[0002]

2. Description of the Related Art Conventionally, from the viewpoint of improving the safety of automobiles,
Various sensors are attached to prevent accidents. Specifically, an ultrasonic sensor is attached to a part of the automobile that is a blind spot of the driver to detect obstacles around the automobile, and a laser radar that detects the distance between the vehicle and the preceding vehicle while traveling is provided in the automobile. For example, there is a vehicle equipped with an alarm to issue a warning when the inter-vehicle distance approaches a predetermined value to prevent a rear-end collision.

However, these are road structures and fixed objects,
It targets vehicles and the like, not pedestrians.
Recently, interest in prevention of pedestrian accidents has increased, and various systems for detecting pedestrians have been proposed. Specifically, there is one described in JP-A-9-328054.

This type of pedestrian detection system is constructed, for example, as shown in FIG. 4, and is an infrared detecting means 3 comprising a combination of a Fresnel lens 1 and a pyroelectric infrared sensor 2.
Mounted on the vehicle body of an automobile, detects infrared radiation from an object in front of the infrared sensor 2 via the Fresnel lens 1, and outputs the output signal of the infrared sensor 2 to the signal processing means 4
Is processed to determine whether the object is a pedestrian, and when it is determined that the object is a pedestrian, the notification means 5 such as a buzzer or a warning lamp notifies the existence of a pedestrian in the vicinity. Has become.

[0005]

However, in the conventional pedestrian detection system described above, the output signal of the infrared sensor 2 is output regardless of whether the object passing in front of the infrared sensor 2 is a pedestrian. If the change occurs and the frequency of the change falls within a predetermined range, it is determined that all the objects are pedestrians, and there is a problem of lack of reliability.

The problem to be solved by the present invention is to enable highly reliable pedestrian detection.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a combination of a Fresnel lens and an infrared sensor and is attached to the body of an automobile through the Fresnel lens to detect a bone-shaped detection area of a fan. Have
An infrared detector for detecting the infrared radiation from the infrared sensor in front of the object that, the object by processing the output signal of the infrared sensor and signal processing means for determining whether a pedestrian In the pedestrian detection system, the signal processing means detects the frequency of the output signal of the infrared sensor and determines whether or not it changes within a predetermined frequency range, and the wave number of the output signal of the infrared sensor. And a wave number determination unit that determines whether or not a predetermined number or more is detected, the signal frequency determination unit determines that the frequency of the output signal of the infrared sensor is within a predetermined frequency range, and the wave number The determination unit determines that the object is a pedestrian when the wave number of the output signal of the infrared sensor is determined to be a predetermined number or more. It is set to.

According to this structure, by combining the Fresnel lens and the infrared sensor, the detection area of the sensor has a fan-shaped bone. Therefore, when a pedestrian crosses the front of an infrared sensor having such a detection area, when the pedestrian enters the detection area, the output signal of the infrared sensor is at a high level, and the pedestrian has a detection area adjacent to the detection area. Since the output signal of the infrared sensor becomes low level when entering the non-detection area between the two, the output signal of the infrared sensor changes at a frequency corresponding to the walking speed of the pedestrian. The frequency at this time falls within the range of approximately 2 to 5 Hz.

On the other hand, when the vehicle crosses in front of the infrared sensor, the infrared sensor reacts because the temperature around the engine room of the vehicle is high. Since the body of the automobile straddles some of the detection areas of the infrared sensor that are distributed in the shape of a fan and passes at a speed higher than the speed of the pedestrian, the wave number of the output signal of the infrared sensor that changes is the walking speed. Far less than in the case of the person. Therefore, even if the frequency of the output signal of the infrared sensor when the vehicle crosses is in the same range of 2 to 5 Hz as that of the pedestrian, the wave number of the output signal of the infrared sensor is significantly different from that of the pedestrian.

Therefore, if it is detected that the output signal of the infrared sensor changes within a predetermined frequency range and that the wave number of the output signal of the infrared sensor is a predetermined value or more, the output of the infrared sensor at that time is detected. Can be easily determined to be due to the passage of a pedestrian, and the pedestrian can be reliably detected.

Further, the present invention is characterized by comprising notifying means for notifying the presence of a pedestrian in the surroundings when the object is judged to be a pedestrian by the signal processing means. .

With this configuration, the presence of a pedestrian can be easily known by the notification of the notification means, and a pedestrian accident can be prevented in advance.

Furthermore, the present invention is characterized in that the infrared sensor is a pyroelectric infrared sensor.

In this case, the pyroelectric infrared sensor can detect a change in infrared rays radiated from the object, which is suitable for constructing infrared detecting means in combination with a Fresnel lens.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. However, FIG. 1 is a block diagram, and FIGS. 2 and 3 are operation explanatory diagrams.

In FIG. 1, 11 is a Fresnel lens, 1
Reference numeral 2 denotes a pyroelectric infrared sensor, which constitutes an infrared detecting means 13 in combination with a Fresnel lens 11, and such infrared detecting means 13 is attached to a predetermined portion of a vehicle body of an automobile, and infrared rays are transmitted via the Fresnel lens 11. Infrared radiation from the object in front of the sensor 12 is detected.

Further, in FIG. 1, 14 is an infrared sensor 1.
A signal processing means for inputting a signal from the infrared sensor 12 and processing an output signal of the infrared sensor 12 to judge whether the object is a pedestrian, 15 is an informing means, and includes a buzzer, a warning lamp, and the like. When the signal processing unit 14 determines that the object is a pedestrian, the notifying unit 15 operates to notify the driver or the like of the presence of the pedestrian in the vicinity.

At this time, as shown in FIG. 2, the detection area A of the infrared sensor 12 when the Fresnel lens 11 is used is, for example, spread in a fan-shaped bone shape, so that a pedestrian passes through each detection area A. When the infrared sensor 12 outputs a high-level output signal when the pedestrian passes between the adjacent detection areas A, the infrared sensor 1
The output signal of 2 becomes low level. Therefore, when a pedestrian crosses in front of the infrared sensor 12, as shown in FIG.
The infrared sensor 12 outputs a signal that changes at a certain frequency. The frequency of the output signal of the infrared sensor 12 at this time falls within the range of approximately 2 to 5 Hz.

By the way, when the automobile crosses the front of the infrared sensor 12, the infrared sensor 12 detects the emitted infrared rays and reacts because the temperature around the engine room of the automobile is high. Thus, when the vehicle crosses in front of the infrared sensor 12, as shown in FIG. 3, some of the detection areas A of the infrared sensor 12 (three in FIG. 3 are distributed in a fan-shaped bone of the vehicle body). ),
In addition, the wave number of the output signal of the infrared sensor 12 that changes is much smaller than that of the pedestrian because it passes faster than the pedestrian.

Therefore, even if the frequency of the output signal of the infrared sensor 12 when the vehicle crosses is in the range of 2 to 5 Hz, which is the same as in the case of a pedestrian, the infrared sensor 12
The wave number of the output signal of is significantly different from that of a pedestrian. For example, if the infrared sensor 12 has four detection areas A as shown in FIG. 2, the wave number in the case of a pedestrian is four, which is the same as the number of the detection areas A, whereas in the case of an automobile, it is at most. It becomes 1-2.

Therefore, the signal processing means 14 detects the frequency of the output signal of the infrared sensor 12 and determines whether or not it changes within a predetermined frequency range (for example, 2 to 5 Hz), and the infrared sensor 12 Of the output signal of the infrared sensor 12 is detected by the signal frequency determination unit 14a. When it is determined that it is within the range and the wave number determination unit 14b determines that the wave number of the output signal of the infrared sensor 12 is equal to or greater than a predetermined number, the target object is determined to be a pedestrian. .

At this time, the detection of the frequency by the signal frequency determination unit 14a is the detection time from when the object begins to enter the first detection area A of the infrared sensor 12 to when it exits the last detection area A, and during that time. It can be calculated from the change in the level of the output signal. For example, a change from the low level to the high level to the low level of the output signal within this detection time corresponds to one wave number.

Therefore, according to the above-described embodiment, the signal frequency determining section 14a of the signal processing means 14 determines whether or not the frequency of the output signal of the infrared sensor 12 is within the predetermined frequency range, and the signal processing means 14 is operated. Wave number determination unit 14b
In order to determine whether the wave number of the output signal of the infrared sensor 12 is a predetermined value or more, it is determined that the frequency of the output signal of the infrared sensor 12 is within a predetermined frequency range and the wave number is a predetermined value or more. It can be easily determined that the output of the infrared sensor 12 at the time of
When either the frequency or the wave number does not satisfy the condition, it can be determined that the cause is other than a pedestrian. for that reason,
The pedestrian and the others can be clearly distinguished and detected, and the pedestrian can be reliably detected.

Further, the driver can easily know the presence of a pedestrian by the notification of the notification means 15, and can prevent a pedestrian accident from occurring.

Although the infrared sensor is the pyroelectric infrared sensor 12 in the above embodiment, a thermopile infrared sensor may be used. In this case, out of the output of the thermopile type infrared sensor, the infrared rays emitted from the heating element such as the hood and incandescent lamp of the automobile are removed by extracting the threshold value equal to or lower than the human body temperature (36 to 37 ° C). However, even if the temperature of the hood of the car is below the threshold and it cannot be distinguished from humans, the frequency of the output signal of the thermopile type infrared sensor can be effectively processed. And by examining the wave number as described above, it is possible to distinguish between a pedestrian and others.

Further, in the above-described embodiment, the notification means 15 notifies only when a pedestrian is detected, but it may be so arranged that the notification is made when the pedestrian is detected and when it is not detected. Of course, in this case, the driver can surely recognize the presence or absence of a pedestrian.

Further, when the signal processing means 14 detects a pedestrian, for example, a start regulation means is provided for taking measures such as forcibly actuating a brake so that the driver starts the vehicle erroneously despite the notification from the notification means 15. As a matter of course, it may be possible to prevent this.

Furthermore, the present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention.

[0029]

As described above, according to the invention described in claim 1, the output signal of the infrared sensor changes within a predetermined frequency range, and the wave number of the output signal of the infrared sensor has a predetermined value. If the above is detected, it is possible to easily determine that the output of the infrared sensor at that time is due to a pedestrian, and it is possible to reliably detect the pedestrian, which is highly reliable. Pedestrian detection can be performed.

According to the second aspect of the invention, the presence of a pedestrian can be easily known by the notification of the notification means, and a pedestrian accident can be prevented in advance.

According to the third aspect of the invention, since the pyroelectric infrared sensor can detect a change in the infrared rays emitted from the object, it is suitable for constituting an infrared detecting means in combination with a Fresnel lens. Is.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is an operation explanatory diagram of the embodiment.

FIG. 4 is a block diagram of a conventional example.

[Explanation of symbols]

11 Fresnel lens 12 Pyroelectric infrared sensor 13 Infrared detector 14 Signal processing means 14a Signal frequency determination unit 14b Wave number determination unit 15 Notification means

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G08G 1/16 B60R 21/00 G01J 1/02

Claims (3)

(57) [Claims] 1. An infrared ray, which comprises a combination of a Fresnel lens and an infrared sensor, is attached to a vehicle body of an automobile, and detects infrared rays emitted from an object in front of the infrared sensor having a fan-shaped bone-shaped detection area through the Fresnel lens. In a pedestrian detection system including a detection unit and a signal processing unit that processes an output signal of the infrared sensor to determine whether the object is a pedestrian, the signal processing unit is the infrared sensor. A signal frequency determination unit that detects the frequency of the output signal and determines whether it changes in a predetermined frequency range, and a wave number determination that detects the wave number of the output signal of the infrared sensor and determines whether it is a predetermined number or more The signal frequency determination unit determines that the frequency of the output signal of the infrared sensor is within a predetermined frequency range. Pedestrian detection system, wherein the object is a pedestrian when the wave number of the output signal of the infrared sensor is determined to be a predetermined number or more by the wave number determination unit. . 2. The informing device according to claim 1, further comprising an informing unit for informing the presence of a pedestrian in the surroundings when the signal processing unit determines that the object is a pedestrian. The pedestrian detection system described. 3. The pedestrian detection system according to claim 1, wherein the infrared sensor is a pyroelectric infrared sensor.