JPH04147087A - Back monitoring system - Google Patents

Abstract

PURPOSE:To reduce occurrence of incorrect information by providing a significant target determining unit which measures brightness etc. of a picked image to determine whether it is a significant target, an azimuth measuring unit of the significant target, a distance measuring unit and a dangerous target determining unit which determines approach of the significant target. CONSTITUTION:Infrared image light reaching from a target is first condensed by an infrared light receiving optical system 2 and focused on an infrared CCD 4. The CCD 4 converts the focused image into a voltage signal, an amplifier 6 amplifies the voltage signal, and a binary circuit 8 converts the signal into '1' and '0'. Then a ratio in longitudinal and lateral lengths of a set of '1' signals in the binary image is calculated in an aspect ratio calculation unit 10, and a significant target determining unit 12 determines whether or not a target is significant from the signal. An azimuth calculation unit 15 calculates an azimuth of the target which has been determined to be significant, and a mirror driving unit 18 controls a mirror 20 so that transmitted laser light 23 directs to the azimuth. A distance calculation unit 36 calculates a distance to the target from time required for a laser light 27 to reach the target and return. A dangerous target determining unit 38 determines a dangerous target if there is an approaching significant target.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a system that detects a flying object or the like approaching from behind an aircraft and issues a warning.

[Conventional technology]

FIG. 5 is a diagram showing a circuit block configuration of a conventional rear warning system using light in the infrared wavelength range.

In the figure, 1 is light in the infrared wavelength range, 2 is an infrared light receiving optical system for condensing the light in the infrared wavelength range, and 3 is light in the infrared wavelength range condensed by the optical system. , 4 is a CCD image sensor sensitive to light in the infrared wavelength range, 5 is the CCD
The video signal output from the image sensor, 6 an amplifier for amplifying the video signal, 7 the amplified video signal, 8 the video signal rO
A binarization circuit that binarizes into J and rN, 9 is a binarized signal processed by the binarization circuit 8, and 40 is a case where the binarization signal 9 contains "1". 13 is a CCD driver for generating clock pulses for driving the CCD image sensor 4; 14 is a clock pulse generated by the driver 13;

Next, the operation will be explained. The light collected by the infrared light receiving optical system 2 is converted into an electric video signal by the CCD image sensor 4. After this video signal is amplified to a required voltage by an amplifier 6, it is separated into rlJ and rOJ by a binarization circuit 8. The alarm generation unit 40 generates an alarm when a 1 is included in the binary signal.

[Problem to be solved by the invention]

Conventional rear warning systems that utilize light in the infrared wavelength range were configured as described above, and were prone to issuing false alarms due to infrared light reflected by clouds, buildings, and the like.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a rear warning system that can reduce the incidence of false alarms.

[Means to solve the problem]

The rear warning system according to the present invention includes a significant target determination unit that determines whether or not the target is a significant target by measuring the brightness and shape of an image captured by an image sensor unit that is sensitive to light in the infrared wavelength range; an azimuth measurement unit that measures the azimuth of the
The apparatus is configured to include a distance measuring section that measures the distance to a significant target, and a dangerous target determining section that determines that the significant target is a dangerous target if it approaches.

[Effect]

The rear warning system according to the present invention selects a significant target candidate by measuring brightness and shape, measures the direction of the significant target candidate by the azimuth measuring section, and emits a measurement signal from the distance measuring section in the direction of the measurement result. Since the approach is detected, the detection rate of false targets can be significantly reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a rear warning system according to an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 5 indicate the same parts. 10 is an aspect ratio calculation unit that calculates the aspect ratio of the binarized image, 11 is the aspect ratio calculated by the aspect ratio calculation unit 10 and the binarized video signal, and 12 is a threat candidate extracted from among them. 15 is an azimuth calculation unit that calculates the direction in which the significant target exists; 17 is an azimuth signal calculated by the azimuth calculation unit 15; 16 is a trigger pulse that issues an oscillation command to the laser oscillator 25; 18 is a A mirror drive circuit receives the azimuth signal 17 and controls the emission direction of the laser beam, and 19 is a drive pulse for driving the mirror 20.

Further, 23 is a laser beam oscillated by a laser oscillator 25, and 24 is a scanning mirror for expanding the irradiation coverage area of the laser beam 23, which is driven by a scanning mirror drive signal 41 sent from a scanning mirror drive unit 42. Ru.

26 is a start pulse for starting the counter 34, 27 is a laser beam reflected from the target,
28 is a laser beam receiving optical system for condensing the reflected laser beam 27; 29 is the condensed laser beam, which is converted into a received signal 31 by an avalanche photodiode 30; 32 is an amplifier that increases the received signal 31 to a required voltage and generates a stop pulse 33 that stops the counter 34;
35 is a count number that measures the time from the laser oscillation to the return of the reflected light, and is converted into a distance signal 37 to the target by the distance calculation unit 36.

Reference numeral 38 denotes a dangerous target determination unit that determines whether the target is dangerous based on the distance signal 37 to the target, and if it is determined to be a dangerous target here, an alarm generation request signal 39 is sent to the alarm generation unit 40. .

Further, FIG. 2 is a diagram showing the dangerous target determination section of FIG. 1 in more detail.

In the figure, 44 is a labeling unit that labels a plurality of significant target candidates, 45 is a labeled significant target distance, and 4
6 is a first memory that stores the labeled significant target distance; 47 is a first memory content that is shifted from the first memory 46 after one surface scan of the scanning mirror; 48 is a memory that stores the first memory content as it is; A second memory 49 is a subtracter that subtracts the contents of the second memory from the contents of the first memory.

Next, the operation will be explained.

First, the infrared image light reaching from the target is transmitted to the infrared light receiving optical system 2.
The light is focused and imaged on the infrared CCD 4. Infrared C
The CD 4 converts the image into a voltage signal and inputs it to the amplifier 6. The amplifier 6 amplifies the imaged voltage signal to the required voltage, and the binarization circuit 8 converts this signal into rN and rOJ.
Convert to

The threshold value at that time can be set arbitrarily.Next, in the binarized video in the aspect ratio calculation unit 10, "
The ratio of the vertical and horizontal lengths of the set of signals of ``1'' is calculated, and the significant target determining unit 1-2 determines from the signal whether the target is due to significance or due to the background. That is, in this embodiment, since the field of view is wide, flying objects and the like are received as "points". On the other hand, since clouds and the like receive light with a certain degree of spread, their aspect ratio becomes vertically elongated and can be determined to be caused by the background.

Subsequently, the orientation calculation unit 15 calculates the orientation of the target determined to be significant. The mirror drive section 18 controls the mirror 20 so that the transmitted laser beam 23 is directed in the direction calculated by the direction calculation section 15. Since the transmitted laser beam 23 has a small spread angle, the probability of hitting the target is small. Therefore, the laser beam 23 is scanned at a certain angle by the scanning mirror 24 to increase the probability of hitting the target. The laser beam 27 that has hit the target and returned is focused onto the photodiode 30 by the laser beam receiving optical system 28. The photodiode 30 converts the received laser light into a voltage signal, which is sent to the amplifier 3.
2, the voltage is amplified to a required voltage and input to the counter 34.

The counter 34 records the passage of time by the oscillation of the laser oscillator 25, and stops when the output signal 33 from the amplifier 32 is input. The distance calculation unit 36 calculates the distance to the target based on this elapsed time. Dangerous target determination section 3
8, the distance to the significant target is monitored for a certain period of time, and if there is a significant target approaching, it is determined that it is a dangerous target and an instruction is issued to the alarm generator 40 to sound an alarm.

Hereinafter, a more detailed explanation of the dangerous target determination section will be given using FIG. 2. First, the labeling unit 44 labels the distances of a plurality of significant targets. Thereafter, the labeled distance is stored in the first memory 46.

Next, when the scanning mirror 24 completes one scan, the contents of the first memory are transferred to the second memory 47. Labeling is performed again in the second scan of scanning mirror 24 and the labeled distances are stored in the first memory. Subsequently, in the subtracter 49, the first
The contents of the same label in the memory and the second memory are subtracted. As a result, an approaching target can be found while the scanning mirror 24 performs one scan.

As described above, according to this embodiment, light in the infrared wavelength range is passively received, and by detecting its aspect ratio, it is determined whether or not it is a significant target, and if it is a significant target, its direction is detected. Since the device is configured to measure distance using an infrared laser and issue an alarm if a target approaches, the probability of issuing a false alarm due to infrared rays emitted by clouds, buildings, etc. can be greatly reduced. Further, the applied laser light acts as an illuminator, which has the effect of increasing the S/N of the image of the significant target captured by the infrared image sensor section. Furthermore, if a flying object approaching an aircraft is passively tracked using infrared rays, the laser light may saturate the sensor and interfere with tracking.

In the above embodiment, the distance measuring section 5 is provided with one laser oscillator, but as shown in FIG. An oscillation unit 115 that oscillates laser light within a wavelength band of 8 to 13 μm is provided, and each reflected light is received by a wavelength band of 3 to 5 μm laser receiving unit 116 and a wavelength of 8 to 13 μm band laser receiving unit 117 to calculate distance. You may go.

In this case, the S/N can be improved by taking the average of the reflected signals of each laser, and it is also possible to improve the S/N by taking the average of the reflected signals of each laser. Even if you don't know if there are any, you can expect a disturbing effect.

In addition, in this FIG. 3, 104 is an azimuth measuring section;
8 is a scanning mirror control section, 109 is a part of the scanning mirror, 111 is a reception optical section, 113 is a distance calculation section, and 106 is a comprehensive judgment section that judges a dangerous target.

Further, as shown in FIG. 4, distance measurement may be performed using a radar that oscillates only when a significant target appears. In this embodiment, radio waves are oscillated only when a significant target appears. It has the effect of reducing the probability of becoming a target for flying objects flying towards the radio wave source.

In addition, in this FIG. 4, 103 is a significant target determination section, 118 is a servo controller section, 119 is an antenna drive section, 120 is an antenna section, 121 is a transmitting section,
122 is a receiving section, and 113 is a distance calculating section.

〔Effect of the invention〕

As described above, according to the rear warning system according to the present invention, it is possible to determine whether or not a significant target is a significant target using the brightness and shape of the image captured by the image sensor section that is sensitive to light in the infrared wavelength range. When detected, the direction is measured and the distance to the significant target is measured using this direction, and when the distance to the significant target decreases, it is determined that the target is dangerous and a warning is issued. This has the effect of greatly reducing the problem of false alarms being issued by treating backgrounds such as clouds and buildings as significant targets.

[Brief explanation of the drawing]

FIG. 1 is a functional block diagram showing a rear warning system according to an embodiment of the present invention, FIG. 2 is a functional block diagram depicting the dangerous target determination section in FIG. 1 in more detail, and FIG. 3 is a distance measuring section. FIG. 4 is a functional block diagram of another embodiment of the present invention using lasers in the 3-5 μm band and 8-13 μm band, and FIG. 4 is a functional block diagram of another embodiment of the present invention using a radar in the distance measuring section Block Diagram FIG. 5 is a functional block diagram of a conventional rear warning system. In the figure, 2 is an infrared light receiving optical system, and 4 is an infrared CCD.
, 8 is a binarization circuit, 10 is an aspect ratio calculation unit, 12,
103 is a target determination unit, 15 is a direction calculation unit, 25 is a laser oscillator, 24 is a scanning mirror, 28 is a laser beam receiving optical system, 30 is an avalanche photodiode, 34 is a counter, 36 is a distance calculation unit, 38 is a Dangerous target determination department, 4
0 is an alarm generation unit, 114 is a 3-5 μm band laser oscillation unit, 115 is an 8-13 μm band laser oscillation unit, 1
09 is part of the scanning mirror, 111 is the receiving optical part, 116 is 3
~5μm band laser receiver, 1F is 8~13μm
In-band laser reception section, 113 is a distance calculation section, 118 is a servo controller section, 119 is an antenna drive section, 12
1 is a transmitter, and 122 is a receiver. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a system that detects an object approaching from behind and issues a warning, it uses an image sensor unit that is sensitive to light in the infrared wavelength range and the brightness and shape of the image captured by this image sensor unit to identify a significant target. a means for determining whether or not a significant target is detected; a means for measuring the bearing when a significant target is detected; a means for measuring the distance to the significant target using this bearing; A rear warning system comprising a means for determining that a target is a target and issuing a warning.