GB2537723A

GB2537723A - Apparatus for detecting approaching objects

Info

Publication number: GB2537723A
Application number: GB1603412.6A
Authority: GB
Inventors: Ruppel Michael; Haan Hubertus; Munzberg Mario
Original assignee: Airbus DS Optronics GmbH
Current assignee: Hensoldt Optronics GmbH
Priority date: 2015-04-21
Filing date: 2016-02-26
Publication date: 2016-10-26
Anticipated expiration: 2036-02-26
Also published as: DE102015106092A1; GB2537723B; GB201603412D0

Abstract

An apparatus 1 for detecting approaching objects comprises a rotating radar device 2, an infrared camera 3 and a signal processing and evaluation unit 4. The infrared camera is mounted directly on the radar device and has at least one infrared detector 3.1. The signal processing and computing unit receives detection signals captured by the radar device and the infrared camera and is configured to use the received detection signals to determine whether an approaching object is present. The infrared detector, which may be an area detector, can be arranged such that its rows or columns run parallel to a direction of the rotation of the radar device. The signal processing and evaluation unit may correlate the received signals, carry out a convolution operation on pixels contained in the detection signals from the infrared camera, or detect an approaching object through use of a threshold value analysis. An approaching object may only be detected by the apparatus if the object is detected in the signals from the radar device and the signal from the infrared camera.

Description

Description:

Apparatus for detecting approaching objects The invention relates to an apparatus for detecting approaching objects.

Rotating radar devices (for example at sea or onshore) for detecting approaching, in particular incoming, objects, for example rockets, drones, mortar attacks or other explosive objects, are sufficiently well known. However, the frequency of false alarms of these conventional radar devices is comparatively high. An excessively low detection threshold often results in false positive detections, that is to say in the triggering of an alarm, even though no object is approaching. However, an excessively high detection threshold results in false negative detections, that is to say an alarm is absent, even though an object is actually approaching.

Infrared cameras or thermal imaging cameras or thermal imaging devices are likewise used to identify approaching objects. Infrared cameras detect the thermal radiation of approaching objects, for example heated missile tips, the heat of exhaust gases or heated components of engines. Such infrared cameras usually allow only one viewing direction, as a result of which a plurality of stationary infrared cameras or the use of a rotor, which is used to horizontally move one or more infrared cameras, is/are necessary if all-round visibility or all-round protection is desired. As a result, monitoring systems having infrared cameras are comparatively cost-intensive.

In addition, the trend for smaller signatures combined with the false alarm rates of the two methods described above is increasingly resulting in the restriction of the respective system performance. -2 -

The present invention is based on the object of specifying an apparatus of the type mentioned at the outset which avoids the disadvantages of the prior art and is distinguished, in particular, by a higher detection accuracy and a reduced false alarm rate.

This object is achieved, according to the invention, by means of an apparatus having the features mentioned in Claim 1.

The dependent claims relate to advantageous embodiments and developments of the invention.

The apparatus according to the invention for detecting approaching objects comprises at least a radar device, in particular a rotating radar device or a radar device which turns at least in an angular range around its own axis, an infrared camera having at least one infrared detector, the infrared camera and/or the at least one infrared detector being arranged directly on the radar device, and a signal processing and evaluation unit which receives detection signals captured by the radar device and by the infrared camera and is set up to use the detection signals supplied to it by the radar device and the infrared camera to detect whether or not an object, in particular an object approaching the apparatus, is present.

These measures provide a simple way of combining the two methods which considerably reduces the false alarms. The infrared camera, in particular the thermal imaging camera, is directly fastened to the radar, thus ensuring a continuous and synchronous movement of the infrared camera and/or of the at least one infrared detector with the rotating radar device. A system for detecting approaching objects using a radar system in conjunction with a thermal imaging camera is:therefore proposed.

Furthermore, a radar device of an apparatus according to the invention can ensure all-round coverage of 360°. Such a radar device may have a horizontal rate of rotation of 360° for every two or fewer seconds and can record a vertical angular range of between 50° and 70°, in particular 60°.

In one advantageous embodiment, the at least one infrared detector of the infrared camera can be arranged on the radar device in such a manner that its rows or columns run parallel to a direction of rotation of the radar device.

In this case, the at least one infrared detector may be in the form of an area detector.

The signal processing and evaluation unit may be set up to correlate the detection signals from the infrared camera and from the radar device locally and in terms of time. In order to reduce the false alarm rate, the detections by the thermal imaging camera and the radar are correlated locally and in terms of time.

In one very advantageous configuration of the invention, it is determined or detected that an approaching object is present only when an approaching object is detected both in the detection signals from the radar device and in the detection signals from the infrared camera. In this advantageous variant according to the invention, a target is detected only when both measurement principles result in the detection. The independence of the two measurements virtually excludes false positive detections. This makes it possible to reduce the detection thresholds of the sensors of the radar device and of the infrared camera or the infrared detector, as a result of which the overall system for detecting approaching objects becomes more precise and more sensitive, which in turn results in false negative detections being able to be reduced. -4 -

The signal processing and evaluation unit may be set up to detect whether an approaching object is present by means of a threshold value analysis.

It is likewise advantageous if the signal processing and evaluation unit is set up to horizontally carry out a convolution operation on the pixels contained in the detection signals from the infrared camera with a sliding window of a calculated smearing width. It is accepted that a fuzzy image is produced on the detector during rotation since a point target is imaged in a manner smeared over a plurality of pixels during the exposure time of 10 ms, for example. The smearing depends on the rotational speed of the system, can be calculated and is exactly horizontal. The convolution operation improves the signal-to-noise ratio, which is produced by the rotation of the radar device and of the infrared camera or the infrared detector on the radar device, before a threshold value analysis is used for detection.

The principle of an exemplary embodiment of the invention is described below using the drawing.

The single figure of the drawing shows a schematic illustration of an apparatus according to the invention for detecting approaching objects.

The figure illustrates an apparatus 1 according to the invention for detecting approaching objects. The apparatus has a rotating radar device 2 and an infrared camera 3 which is illustrated in a highly simplified manner and, in the present exemplary embodiment, is in the form of a thermal imaging camera. The infrared camera 3 has at least one infrared detector 3.1 in the form of a thermal imaging detector. The infrared camera 3 or at least the at least one infrared detector 3.1 is arranged directly on the radar device 2. Such an arrangement ensures the continuous and synchronous movement of the infrared camera 3 and/or of the at -5 -least one infrared detector 3.1 with the movement of the radar device 2. Furthermore, the radar device 2 can ensure all-round coverage of 360°. In this case, the radar device 2 may have a horizontal rate of rotation of 360° for every 2 s and may record a vertical angle of between 50° and 70°, in particular 60°.

Both thermal imaging ranges such as LWIR, MWIR, VLWIR, FIR and SWIR, NIR can come into consideration for the infrared cameras 3. In particular, thermal imaging cameras in the medium infrared range (MWIR), in particular of approximately 3 pm to 5 pm, or in the long-wave infrared range, in particular of approximately 7 pm to 14 pm, preferably of approximately 8 pm to 12 pm, are suitable as infrared cameras 3.

The radar device 2 and the infrared camera 3 are communicatively connected to a signal processing and evaluation unit 4 (illustrated in a simplified manner) of the apparatus 1. The detection signals captured by the radar device 2 and by the infrared camera 3 can be forwarded to the signal processing and evaluation unit 4 via corresponding connections 5 (indicated using dashed lines), for example commercially available data cables or radio connections, for example Bluetooth, WLAN or the like. The signal processing and evaluation unit 4 may be set up to horizontally carry out a convolution operation on the pixels contained in the detection signals from the infrared camera 3 with a sliding window of a calculated smearing width. The detection signals captured by the radar device 2 and the infrared camera 3 are processed in the signal processing and evaluation unit 4 in such a manner that it is possible to provide information relating to whether an approaching object is present. The signal processing and evaluation unit 4 is therefore set up to use the detection signals supplied to it by the radar device 2 and the infrared camera 3 to detect whether or not an approaching object is present. The signal -6 -processing and evaluation unit 4 may be set up to detect whether an approaching object is present by means of a threshold value analysis. In order to improve the signal-to-noise ratio, it is possible to use an infrared detector which, in sync with the rotational speed, adds signals inside an infrared CCD line in a similar manner to the Time Delay and Integration (TDI) method of infrared line detectors.

The signal processing and evaluation unit 4 may also be set up to correlate the detection signals from the infrared camera 3 and the detection signals from the radar device 2 locally and in terms of time. Provision may be made for it to be detected that an approaching object is present only when an approaching object is detected both in the detection signals from the radar device 2 and in the detection signals from the infrared camera 3.

The at least one infrared detector 3.1 of the infrared camera 3 is arranged on the radar device 2 in such a manner that its rows or columns run parallel to a direction of rotation of the radar device 2. In the present exemplary embodiment, the at least one infrared detector 3.1 is in the form of an area detector. -7 -

List of reference symbols 1 Apparatus according to the invention 2 Radar device 3 Infrared camera 3.1 Infrared detector 4 Signal processing and evaluation unit Connections -8 -

Claims

Patent claims: 1. Apparatus (1) for detecting approaching objects, at least comprising: - a radar device (2), in particular a rotating radar device; - an infrared camera (3) having at least one infrared detector (3.1), the infrared camera (3) and/or the at least one infrared detector (3.1) being arranged directly on the radar device (2); and a signal processing and evaluation unit (4) which receives detection signals captured by the radar device (2) and by the infrared camera (3) and is set up to use the detection signals supplied to it by the radar device (2) and the infrared camera (3) to detect whether an approaching object is present.
2. Apparatus (1) according to Claim 1, the at least one infrared detector (3.1) of the infrared camera (3) being arranged on the radar device (2) in such a manner that its rows or columns run parallel to a direction of rotation of the radar device (2).
3. Apparatus (1) according to Claim 1 or 2, the at least one infrared detector (3.1) being in the form of an area detector.
4. Apparatus (1) according to one of Claims 1, 2 and 3, the signal processing and evaluation unit (4) being set up to correlate the detection signals from the infrared camera (3) and the detection signals from the radar device (2) locally and in terms of time.
5. Apparatus (1) according to one of Claims 1 to 4, in which case it is detected that an approaching object is present only when an approaching object is detected both in the detection signals from the -9 -radar device (2) and in the detection signals from the infrared camera (3).
6. Apparatus (1) according to one of Claims 1 to 5, the signal processing and evaluation unit (4) being set up to horizontally carry out a convolution operation on the pixels contained in the detection signals from the infrared camera (3) with a sliding window of a calculated smearing width.
7. Apparatus (1) according to one of Claims 1 to 6, the signal processing and evaluation unit (4) being set up to detect whether an approaching object is present by means of a threshold value analysis.