System and Method for Restricting Access through a Mantrap Portal

Abstract

A method and system provides increased levels of security for a mantrap portal by continuously monitoring two zones of the mantrap; a primary zone and a secondary zone. A primary sensor determines that exactly one or zero people are present in the primary zone when requesting access into a secured area. A secondary sensor determines that exactly zero people are present in the secondary zone when access to the secured area is granted. The primary and secondary sensors in combination can detect piggyback events and tailgating events before granting access to a secured area. Further, the primary and secondary sensors in combination can detect the presence of unauthorized persons in a mantrap prior to granting access to the mantrap for exit from a secured area.

1 . A method of controlling access to a secured area using a mantrap, the mantrap having a landside door and an airside door, the method comprising: 
 monitoring a primary zone, the primary zone comprising a region within the mantrap having an area less than the area of the mantrap, to determine the presence of one person in the primary zone;    monitoring a secondary zone, the secondary zone being an area comprising a region of the mantrap not including the primary zone, to determine the absence of any persons in the secondary zone; and    controlling access through the landside door and the airside door in response to the steps of monitoring the primary zone and monitoring the secondary zone.    
   
   
       2 . The method according to  claim 1  wherein the step monitoring the primary zone further comprises: 
 acquiring a stereo image of the primary zone;    computing a first set of 3D features from the stereo image of the primary zone; and    determining the presence of one person in the primary zone using the first set of 3D features.    
   
   
       3 . The method according to  claim 2  wherein the step of monitoring the secondary zone further comprises: 
 acquiring a stereo image of the secondary zone;    computing a set of 3D features from the stereo image of the secondary zone; and    determining the absence of any person in the secondary zone using the second set of 3D features.    
   
   
       4 . The method according to  claim 1  further comprising setting an alarm signal if the step of monitoring the primary zone fails to determine the presence of one person in the primary zone.  
   
   
       5 . The method according to  claim 4  further comprising setting an alarm signal if the step of monitoring the secondary zone fails to determine the absence of any persons in the secondary zone.  
   
   
       6 . The method according to  claim 2  further comprising filtering the first set of 3D features to exclude features that are computed to be substantially near the ground in the primary zone.  
   
   
       7 . The method according to  claim 3  further comprising filtering the second set of 3D features to exclude features that are computed to be substantially near the ground in the secondary zone.  
   
   
       8 . The method according to  claim 1  wherein both the step of monitoring the primary zone and monitoring the secondary zone are performed by a single three-dimensional machine vision sensor.  
   
   
       9 . A system for controlling access to a secured area using a mantrap, the system comprising: 
 a mantrap having a lockable landside door and a lockable airside door;    a primary sensor to detect the presence of a person in a primary zone within the mantrap, the primary zone comprising a region within the mantrap having an area less than the area of the mantrap;    a secondary sensor to detect the absence of any persons within a secondary zone within the mantrap, the secondary zone comprising a region within the mantrap not including the primary zone;    a controller coupled to the primary sensor and the secondary sensor, the controller actuating the lockable landside door and the lockable airside door in response to the output of the primary sensor and the secondary sensor.    
   
   
       10 . The system according to  claim 9  wherein the primary sensor is a three-dimensional machine vision sensor adapted to monitor a first volume of space directly above the primary zone.  
   
   
       11 . The system according to  claim 10  wherein the secondary sensor is a three-dimensional machine vision sensor adapted to monitor a second volume of space directly above the secondary zone.  
   
   
       12 . The system according to  claim 10  wherein the secondary sensor comprises a plurality of three-dimensional machine vision sensors, the plurality of three dimensional machine vision sensors adapted to cooperatively monitor a second volume of space directly above the secondary zone, and wherein the controller is cooperatively coupled to each of the plurality of three dimensional machine vision sensors.  
   
   
       13 . The system according to  claim 10  wherein the secondary sensor is a presence/absence detector.  
   
   
       14 . The system according to  claim 13  wherein the presence/absence detector is a sensor selected from the list consisting of a pressure-sensitive mat, a light beam emitter/detector pair, and an infra-red motion sensor.  
   
   
       15 . A method for detecting objects in a mantrap, the method comprising: 
 acquiring a stereo image of a region of the mantrap, the stereo image comprising a plurality of two-dimensional images of the region;    computing a set of 3D features from the stereo image;    determining the absence of any person in the region using the set of 3D features;    comparing one of the plurality of two dimensional images of the region to a baseline image; and    detecting an object in the mantrap from the step of comparing.    
   
   
       16 . The method according to  claim 15  wherein the baseline image is computed from a plurality of images of the region of the mantrap when no known objects are present.  
   
   
       17 . The method according to  claim 15  further comprising combining the baseline image with at least one of the plurality of two-dimensional images of the region if no objects are detected.