WO2006097920A2

WO2006097920A2 - System for deterring intruders

Info

Publication number: WO2006097920A2
Application number: PCT/IL2006/000325
Authority: WO
Inventors: Amit Meyuhas; Oz Harpaz; Josef Melamed
Original assignee: Rafael-Armament Development Authority Ltd.
Priority date: 2005-03-13
Filing date: 2006-03-13
Publication date: 2006-09-21
Also published as: WO2006097920A3

Abstract

A system for the prevention of intrusions into a guarded zone employing Isolated watch posts (IWPs) each employing a set of reconnaissance tools looking over a field of view covering a part of a border line. Each IWP reports to a control center using a communications system. A typical IWP employs a lighting system for illuminating the scene, a video motion detector for detecting movement in the field of view and processor for automatically detecting motion and generally processing sensor data. The IWPs are each connected to a low voltage power source. Preferably, the lighting system is includes a simple or compound LED source

Description

SYSTEM FOR DETERRING INTRUDERS

TECHNICAL FIELD OF THE INVENTION

The present invention is in the field of security of border zones. More specifically the invention relates to systems for detection and prevention of intrusions into guarded zones.

BACKGROUND OF THE INVENTION

In US patent 5,980,123, an intruder detection system is disclosed, incorporating a plurality of detection units each of which containing typically a non imaging sensor and a camera. The field of view of each unit is such that a complete coverage of the area to be guarded is obtained as well as a complete coverage of the perimeter of the guarded zone. In response to the non imaging sensor detecting a potential intruder, the video camera is automatically activated. A VMD (video motion detection) typically analyses the camera's output to automatically detect motion.

In a co - pending application IL 167404 by the same applicant the contents of which are incorporated herein by reference, an intruder detection system is disclosed, incorporating a plurality of detection units each of which containing an infra - red sensor and a camera. The invention is implemented in the framework of a given infrastructure of discretely distributed isolated watch posts (IWPs) along a border line, each one supplied with a set of reconnaissance tools and a communications link. The field of view of each unit is such that a complete coverage of the area to be guarded is obtained as well as a complete coverage of the perimeter of the guarded zone. In response to detecting an intruder an alert may be issued invoking a manual response.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic description of a distribution plan of the discretely distributed isolated watch posts, in consideration of the zonation of areas adjacent the border line;

Fig. 2 is a schematic description of exemplary coverage zones relating to specific sensors on board an isolated watch posts;

Fig. 3 is a schematic description of the camera downlooking angle associated with the detection of movement; Fig. 4 is a general description of the stepwise implementation of the method for deterring intruders;

Fig. 5 is an example of the use of zonation in the detection of an intruder;

Fig. 6 is an example of the use of zonation in the detection of an intruder;

Fig. 7 is a schematic description of the wired LAN connecting isolated watch posts.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention is implemented in an infrastructure of discretely distributed isolated watch posts (IWPs) along a border line, such that each IWP has a field of view covering a part of the border line, preferably overlapping a field of view of adjacent IWP. Each IWP is supplied with a set of reconnaissance tools and a communications link. Typically a IWP_n has adjacent IWP_n-! and a IWP_n+i on both sides, respectively. The individual IWP employs a video camera feeding a processing module that is able to run a motion detection algorithm as known in the art, on the video data acquired. The IWPs report to a manned control center, such that the control center is able to verify the scenarios associated with the consequences of finding a potential intruder. The list of reconnaissance tools used in a IWP of the invention consists of at least a video camera. In some embodiments the IWP employs also a non imaging IR detector. Typically, the video camera is always active such that in comparison with the prior art described above. In a preferred embodiment of the invention, it is active also at night, thereby extending the reconnaissance aspect of the IWPs to the dark hours. To facilitate night vision, the embodiments of the invention make a provision for artificial light that illuminates a significant portion of the field of view, at least near the border line, to detect possible intruders in advance of their actual intrusion. The illumination is typically activated automatically by a sensor that detects darkness, as defined by the user. In a preferred embodiment of the invention, the illumination is provided by a high power LED (light emitting diodes). The set of reconnaissance tools provided with each IWP of the invention, constitutes a source of several distinct information types that by a suitable fusion algorithm is set to provide an appropriate intrusion alarm. The intrusion alarm provided by the system of the invention is expected to enable deterrence of the intruder before such intruder has reached the borderline, be it a physical or a virtual entity. In order to better explain the method of the invention, the setting is explained first. Reference is first made to Fig. 1 , which looks from above at the scenery. Borderline 20, is furnished with IWPs 22 typically distributed in equal distances or by any other distribution rationale. The topography and elements in the field may be taken in consideration as, but typical distances are in the range of tens to hundreds of meters. The secure zone, is at the right of the borderline 20. In each IWP, a narrow field of view thermal infra - red non imaging sensor (NFVTIR) looks sideways in a direction diagonal to the border 20, covering a narrow field of view 24. The zone right next to the borderline is defined as zone 4, delineated to the left by virtual line 26. Zone 3 is the zone delimited to the right by line 26 and to the left by the right flak of the field of view 24. Zone 2 is the zone covered by the field of view of the NFVTIR. Zone 1 is the zone outside of the zone 4, zone 2 and delineated to the left by a virtual line 28, and zone 0 is the zone outside of the guarded zone. Looking at the more functional aspects of the intrusion detection, Fig. 2 to which reference is now made, describes the geometrical relationship between an intruder 34 and the IWP 22 having a field of view the center of which is marked by line 36. The video camera of IWP 22 has a field of view having an angle delimited by double headed arrow 38. To describe the movement detecting algorithms employed, a movement vector 40 is drawn, having two perpendicular components, the IWP progress component 42 and the perpendicular component 44. When the intruder 34 is within the field of view of the video camera of IWP 22 and is generally approaching the borderline 20 by moving as described by vector 40, the video motion detection algorithm (MDA) using camera data would not be able to recognize the progress component 42 of movement heading directly towards the camera. The perpendicular component 44 of movement is discernable. In some embodiments of the invention, a size change detection algorithm (SCDA) is employed, expressing a change in size of an intruder as a measure of change of distance from the IWP. The SCDA would be an essential tool for detecting movement if there is no perpendicular component associated with that movement. Cooperative movement detection (COMD) involving two or more IWPs is possible, depending on the communications facilities interconnecting the IWPs. COMD allows the discerning of movement when a single IWP is not able to discern a movement because of unfavourable movement direction of the intruder or because of the existence of hidden areas. Considering the dimensionality of the real world, a video camera installed at the top of the IWP typically looks down upon an intruder. This aspect is further explained with reference to Fig. 3. IWP 50 consists of, schematically, a pole 52 and a video camera 54 connected to data processor (not shown). The component of movement vector that could indicate progress of the intruder is a downwards looking vector 56 which is interpreted as the position in the vertical plane of the actual movement in the positive or negative direction of the IWP having a vertical vector 58, as the intruder progresses from position 60 to position 62.

The non imaging sensors

Seismic or infra red (IR) sensors can be used as non imaging sensors. Either one or a plurality of such sensors may be applied in each IWP. The field of view of the IR sensors of the system of the invention is typically narrow. The narrow field of view intends to keep a high scene resolution, as will be explained below. Although narrow, the field of view has vertical viewing angle large enough to accommodate for walking, reclining or crawling figures at a distance defined.

Rules (postulates) of detection and detector usage

A potential intruder may be detected first by either the non imaging (such as the IR detector) or by the movement detection modules. Cooperative movement detection is either applied or not depending on the hardware/software available, and especially on the communications facilities. The COMD can be implemented at either of two levels. The interaction can be effected by direct communications between IWPs or by intervention of a distributed communications systems such that, for example, each IWP is an end point of a LAN (local area network) and the two LANs communicate by a WAN (wide area metwork). At level one interaction, the actual border progress component (BPC) of the movement detected is analysed, i.e. finding out whether the movement of an object detected actually heads towards the guarded border line. At level two interaction, the communications traffic between the IWPs is typically less intensive, for example one IWP analyses a movement component heading towards an adjacent IWP, sending an alert signal to the adjacent IWP.

Based on experience in the field, several postulates or rules are implemented forming the grounds for the intruder detection schemes in order to reduce false alarms. Rule 1 specifies that a connection is likely to exist between the velocity of an approaching object and the probability of the object being a potential intruder. The postulate calls for measuring the BPC of the movement of the approaching object. This can be done by applying various detection algorithms, cooperative or not. The SCDA is typically performed on a camera output of a single IWP. The increase in size can give indication about the velocity of the approaching object, but a prior knowledge of the actual distance of the object from the detecting IWP has to be taken in account. Therefore, and for various other reasons an additional postulate is implemented. Rule 2 specifies that the actual distance of the potential intruder from the border line changes the alarm threshold level (ATL). The ATL is lowered as the distance is shorter to the border line. In combination, the alarm threshold level depends on the distance of the suspected intruder. Rule 3 specifies that the persistence of a moving object is a factor determining the ATL, therefore a high persistence of moving towards the border line is associated with a low ATL.

Examples of schemes of the implementation of the above rules using the detector system of each IWP used alone or in a cooperative mode follow. Before, a few definitions are made to help describe the sequence of steps in alarming the control center. A general scheme showing the steps of events leading from the early detection of movement to the actuation of an alarm are described in Fig. 4. In step 80 a movement is detected, in step 82 the moving object is defined as a suspect. In step 84 the status of suspect is changed to intruder. In step 86 an alarm is actuated in the control center. The transition from a mere moving object through the stages till the alarm is actuated follows several optional schemes as dictated by the facilities available, and administrative or technical directives.

Example 1

The scheme is explained using the zonal definitions as described in Fig. 1 to which reference is again made. In Fig. 5 to which reference is now made, one scheme of early detection is described in general. First movement is detected in step 90. The movement is detected by an IR detector of a certain IWP_n and is therefore in zone 2. However, the proximity to the border line is checked subsequently in step 92, which queries the reconnaissance system either of IWP_n or in cooperative modes of IWP_n+i and IWP_n-i on both flanks, along the border line. If indeed the moving object is found as existing in zone 0, the alarm level is kept as before in step 94. If the moving object is found in zones other than zone 0, namely has progressed to a more proximal position, it is now declared as a suspect in step 96 and the alarm level .

Example 2. In this example, a scheme is described in reference to Fig. 6 wherein a moving object is being detected by the video motion detection process at IWP_n, in step 102 and assuming that a moving object has not been detected by an IR detector of the IWP, the next stage is to check whether the movement is associated with zone 0 in step 104. If it is, the alarm level is kept constant in step 106. If the movement is not limited to zone 0, the next query that the system in to answer is whether the movement is in zone 1 in step 108. If it is, the status of the moving object is changed to suspect in step 110 and then, the movement detection is set to check whether the movement is consistent in step 112, having a substantial component in the direction of the border line. If the movement is not in zone 1 in step 114 the status is changed to suspect. Then, in step 116 it is verified whether the movement detected is in zone 4, in which case an alarm is actuated in the control center at step 118.

The communications network

The preferred communications means to connect each IWP with the control center and possibly with other IWP is an IP network (a third layer implementation in the ISO system). Each IWP reports to a regional command center (RCC), typically but not necessarily located in association geographically with the control center which functions as a central event tracker and an on - site operational manager. The region size is not defined rigidly but it rather depends typically on various administrative considerations. The communications system can be wired or wireless. If wiring is used, copper and or fiberoptic lines can be employed.

In a preferred embodiment of the invention, a ring LAN is implemented for connecting the IWPs to the control center. To ring 128 are connected, in series, network switches 132 to each of which is connected a respective IWP. Physically, the network switch is in the IWP or associated with a different structural element. All the data supplied by a IWP is passed through the network to the ring and through one or more second hierarchical order network switch 134. The particular LAN architecture described herein used network switches in two hierarchical orders: a first hierarchy IWP network switch associated with each IWP and one or more second hierarchical order network switches for connecting the ring to the control center, directly or indirectly. The ring typically is occupied by up to about 50 IWP and the wiring is either copper or fiber optic. In another embodiment of the invention, the first hierarchical order network switches are connected serially forming a non annular string, with one or more second hierarchy network switches on the string.

Power supply to the IWPs and power expenditure considerations

End users of power suppliers usually obtain a medium voltage supply, typically between 110 to 250 volts AC. In accordance with the present invention, the commercial electric supply is downconverted to a low voltage (12

- 48 volts) supply for supplying the individual IWPs of the system of the invention. Typically the advantage over a regular 220 volts AC used by more conventional lighting installations is in the lower cost of installation, due to cheaper cables and labour, and to the less demanding safety regulations involved.

In one preferred embodiment of the invention, the list of reconnaissance tools used by a IWP of the invention consists of at least a video camera. Some watch posts employ also one or more non imaging IR detectors. The video camera may be always active, including during the dark hours, such that the reconnaissance aspect of the IWP is active also at night. To facilitate night vision, this preferred embodiment of the invention makes a provision for artificial light that illuminates a significant portion of the field of view, at least near the border line, to detect possible intruders in advance of their actual intrusion. Light sources are not necessarily installed on each IWP. In a preferred embodiment of the invention, the illumination is provided by a high power LED (light emitting diodes). Such LEDs are currently available that consume from less then one to several watts. Several advantages are associated with using LED lights. One is their extended durability and meager maintenance requirements, in this respect also the endurance of the LEDs to mechanical stress is high. Another advantage is the low voltage needed for activation and function. Yet another advantage is the uniformity of distribution of light over the illuminated range. This uniformity facilitates the exploitation of the full dynamic range of the camera over the illuminated scene for detecting reflections, without the risk of saturation or insufficiency of illumination in zones of the illuminated scene. Yet another advantage of LEDs is the comparatively high lighting efficiency. In technical terms a relatively high number of lumens per watt consumed is achieved. This efficiency can be obtained by the use of fluorescent light but fluorescent light surfer from large volume required for delivering enough lumens. With respect of this aspect, LED lights are point emitters which facilitate the effective use of optical lenses which promote the uniform lighting and distribution of light intensities over the scene.

To obtain a better efficiency of the light source, it may be useful to install more than one source, typically two LEDs on a IWP. Additionally, a mechanical search mechanism for moving the light source about together with the associated cameras may be applied. Searches can be performed by applying remote control mechanical surveys. The increase the power efficiency of the video camera it is useful to match the maximal spectral sensitivity efficiency of the camera with that of the light source.

The illumination can be activated automatically by a sensor that detects darkness, as defined by the user. The lighting system of the invention can also be used for waking up lighting, such as when a another sensor detects the approaching intruder, as by IR or mechanical sensor, that wakes up the light source. In this respect, the LED have the advantage over fluorescent light of having negligible time delay for activation. In fluorescent light, time delay may last for a few seconds.

Claims

1. A system for the prevention of intrusions into a guarded zone, said system including isolated watch posts (IWPs) each employing a set of reconnaissance tools looking over a field of view covering a part of a border line, and wherein each one of said IWPs report to a control center, said system comprising: • a communications system for connecting at least each of said IWPs with said control center;

• a lighting system for illuminating the scene;

• a video motion detector for detecting movement in said field of view; • a source of power, and

• at least one processor for automatically detecting motion, and for analysing intrusions.

2. A system for the prevention of intrusions as in claim 1 further including a non imaging sensor associated with each IWP and wherein said at least one processor accepts data of said non imaging sensor.

3. A system for the prevention of intrusions as in claim 2 wherein said non imaging sensor is a thermal IR sensor.

4. A system for the prevention of intrusions as in claim 2 wherein said non imaging sensor is a seismic sensor.

5. A system for the prevention of intrusions as in claim 1 , and wherein said power is supplied as 12 to 48 volt current to said IWPs

6. A communications system for collecting data from isolated watch post (IWPs) and for transmitting said data to a control center, wherein each IWP connects through a network switch and wherein each connecting switch connects in series to a neighbouring network switch forming a string and wherein at least one network switch in said ring connects the ring to said control center.

7. A communications system as in claim 1 and wherein said string is a ring.

8. An intruder detection system incorporating a plurality of watch posts, wherein each said watch post employs at least a video camera for providing data to a motion detection processing module, and wherein at least one light source for illuminating the scene of said camera at dark hours is a LED light source.

9. An intruder detection system incorporating a plurality of watch posts as in claim 7, wherein said at least one LED light source is a high power LED.

10. An intruder detection system incorporating a plurality of watch posts, wherein said at least one LED light source is a high power LED, consuming power in the order of about one to several watts each.

11. A method for illuminating a scene of a watch post employing a video camera, wherein lighting for said camera at night is provided by at least a light source having a high lumens per watt lighting efficiency and has a uniform distribution of light.

12. A method as in claim 11 and wherein said light source is a point emitter.

13. A method as in claim 11 and wherein lighting is provided by several light sources.