Abstract:
A container unit door and container monitoring system are disclosed. The container unit door comprises a first layer of a first polyester epoxy glass fiber composite material, a second layer of a second polyester epoxy glass fiber composite material and, a core sandwiched between the first and second layers, wherein the door is substantially transparent to radio frequency radiation. The monitoring system includes a communications system ( 200 ) embedded in the door.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a container door, a container monitoring system and a manufacturing method for such a door, that are particularly applicable for use in the tracking and monitoring of mobile container units and most particularly to ISO shipping container tracking and monitoring. 
       BACKGROUND TO THE INVENTION 
       [0002]    A container (also known as an intermodal container, freight container, ISO container, or shipping container) is a standardized size reusable unit that is typically formed from steel. Containers are used for efficient and secure storage and movement of materials and products within a global containerized freight transport system. A container can be moved from one mode of transport to another (from ship, to rail, to truck) without unloading and reloading the contents of the container. Lengths of common containers, which each have a unique ISO 6346 reporting mark, vary from 8-foot (2.438 m) to 56-foot (17.07 m) and heights vary from 8-foot (2.438 m) to 9 feet 6 inches (2.9 m). There are reportedly over seventeen million intermodal containers in use in the world of varying types to suit different cargoes. For air freight an alternative, lighter, IATA-defined Unit Load Device is used which nevertheless is considered a container for the purposes of this application. 
         [0003]    Tracking, tracing and monitoring of shipping containers is a worldwide issue. Containers today may travel many thousands of miles and be under the control of many different persons during that journey. Not only are there safety and security concerns associated with what may be held in the containers, particularly the ISO shipping types used to convey goods in shipping freighters and the like, there can also be a risk that the shipped goods may be spoiled, contaminated or otherwise interfered with. 
         [0004]    Various security measures have been suggested and/or are in use in connection with shipping containers. 
         [0005]    The most common form of security is that of padlocking and the addition of a breakable seal. The seal is often attached to the door handle to detect if the container has been opened. The seal is commonly embossed with a number that also appears on a shipping manifest. Thieves have devised several ways of gaining access into shipping containers, some of which involve removal and replacement of all or part of the door hardware fasteners so that the seals and locks will not appear to have been disturbed. 
         [0006]    There are a number of improved seals on the market such as the “sealock” (www.sealock.com), which claim to improve container security. They require tools such as an angle grinder and cable cutters to remove. The manufacturer claims that criminals are unlikely to carry such tools, but with battery powered angle grinders readily available this is claim is now optimistic. 
         [0007]    The product known as “containertag” utilizes an active radio-frequency identification tag (RFID). The active RFID tag&#39;s coaxial leads are inserted through the lock fixture of the container, arming the tag tamper feature. If the container door is opened or the cable of the tag cut, the tag immediately and periodically transmits a silent alert signal. This signal can be picked up aboard the carrier or at the point of arrival. When the tag is interrogated the reading hardware will alert the operator that the electronic seal has been broken. This particular family of tags has the optional capability to send an alert if a threshold temperature is exceeded. A serious issue with RFID tags is that even for active tags the reading range rarely exceeds a few metres. RFID tags in general do not have a capability to determine the time when the tampering occurred. This could cause difficulty in determining who to hold accountable for any theft and under what jurisdiction they should be prosecuted. 
         [0008]    More advanced tracking systems have been proposed such as that disclosed in WO2011073972 in which a body section is attachable to an inside surface of a container proximate the door frame such that an end protrudes through a gap in the door frame connecting to an antenna module mounted outside of the container. The antenna modules allow tracking of, and communication with, the container. It will be appreciated that gaps in door frames result in a compromise to the integrity of the container. Having components on both the outside and inside of the container also adds complexity and security vulnerabilities. 
       STATEMENT OF INVENTION 
       [0009]    According to an aspect of the present invention, a container unit door comprising: a first layer of a first polyester epoxy glass fiber composite material; a second layer of a second polyester epoxy glass fiber composite material; and, a core sandwiched between the first and second layers, wherein the door is substantially transparent to radio frequency radiation. 
         [0010]    The first and second layers is preferably of material selected from the group including E-glass  fibre/polyester, A-glass fibre/polyester, C-glass fibre/polyester and R-glass fibre/polyester. 
         [0011]    The first and second layers may be of the same or of different materials. 
         [0012]    Most preferably, the first and second layers are of E-glass fibre/polyester. 
         [0013]    The core may comprises a plywood panel. 
         [0014]    The door may further comprise a coating over exterior surfaces of the first and second layers, the coating arranged to protect the first and second layers from Ultra Violet radiation. 
         [0015]    Preferably, the door further comprises one or more electronics systems including a communications system substantially encapsulated within the door by at least one of the first and second layers. 
         [0016]    The door may further comprise one or more communications antennae integrated within the door and connected to the communications system. 
         [0017]    Each of the one or more antennae may extend in a plane parallel to a longitudinal axis of the door and is or are encapsulated by at least one of the first and second layers. 
         [0018]    The door has an interior and an exterior side, preferably, said encapsulation is arranged to cause the or each antennae to be substantially physically inaccessible from an exterior side of the door. 
         [0019]    The communications system preferably includes a wireless mesh node such as a ZigBee node arranged to form a wireless mesh network with other wireless mesh nodes in the vicinity. 
         [0020]    Preferably, the door comprises a radome for the communication system. 
         [0021]    The radome may comprise a single laminate. Preferably, the radome has a substantially constant thickness with tolerances of approximately±0.2 to 0.5 mm. 
         [0022]    The electronics systems preferably include a container monitoring system arranged to monitor one or more properties of a container to which the container unit door is attached. The communications system is preferably arranged to interface with the container monitoring system. 
         [0023]    The door may further comprising one or more sensors embedded in the door, the monitoring system being arranged to interface with the one or more sensors to monitor properties of the container. 
         [0024]    The door may further comprise an intake fan embedded in an interior side of the door when installed in a container and arranged to pass an air sample from the container to one or more of the one or more sensors. 
         [0025]    The sensors may be selected from a set including: a CO 2  sensor, a volatile organic compound sensor, a radiation sensor, a switch to detect door opening and a vibration sensor. 
         [0026]    According to another aspect of the present invention, there is provided a container monitoring system comprising:
       a container unit including a container unit door comprising:
           a first layer of a first polyester epoxy glass fiber composite material, a second layer of a second polyester epoxy glass fiber composite material, and, a core sandwiched between the first and second layers, wherein the door is substantially transparent to radio frequency radiation; and,   one or more electronics systems including a communications system substantially encapsulated within the door by at least one of the first and second layers and one or more sensors embedded in the door and arranged to monitor properties of the container, the one or more sensors being arranged to communicate data on said monitored properties to the communications system;   
           a communication unit external to said container unit and arranged to communicate with said communications system to obtain data on said monitored properties.       
 
         [0031]    The container monitoring system may comprise a plurality of container units, wherein the communications system of each container unit includes a wireless mesh node arranged to form a wireless mesh network with the wireless mesh nodes of other container units in the vicinity and arranged to route communications to the communications unit via said wireless mesh network. 
         [0032]    In one embodiment, the door comprises first and second layers of a polyester epoxy glass fiber composite material sandwiching a core material therebetween. The door is substantially transparent to radio frequency radiation and preferably has substantially no carbon content mixed in the composite material. 
         [0033]    Preferably, the door includes one or more electronics systems including a communications system encapsulated inside the door by at least one of the composite layers. The electronics systems may include one or more antennae integrated within the door making them robust, invisible and inaccessible. 
         [0034]    The composite is preferably formed from an E-glass, A-glass, C-glass or R-glass fibre/polyester. The core preferably comprises a plywood panel. 
         [0035]    The composite door preferably functions as a radome for the communication system. E glass/polyester has a relative dielectric constant of 6.1 and gives sufficient RF transmittance for this application. This material provides a cost effective solution compared to other types of composite. The glass fibre based composite material together with a high quality manufacturing method enables manufacturing of laminates with good radome characteristics. The radome is preferably made from a single laminate and has a substantially constant thickness with tolerances of around±0.2-0.5 mm. 
         [0036]    Embodiments of the present invention in the form of a composite ‘smart’ door can be used in both new-build containers and retro-fit environments. In preferred embodiments, the door interfaces with, or includes, systems selected from tracking, monitoring for likely threat scenarios such as, namely chemical explosives, Radiological Dispersal Devices (RDDs), presence of stowaways and theft and loss of the container. Embodiments of the present invention enable enhanced tracking and load verification because pre-screening of containers is possible before the container even reaches the port. Risk profiling will be simplified and the need for certain types of scanning and hand searching reduced. 
         [0037]    Preferred features include:
       testing to the ISO 1496 standard   fittable to new containers at the point of manufacture.   retro fittable to existing metal shipping containers   substantially transparent to radio frequency communication   Antennae can be fitted inside the body of the door to protect against damage/sabotage   Sensor system may be included for use in detecting selected threats including intruders, CO2, VOCs and Radiation.   An early warning system may be included to communicate to one or more destinations (optionally including local or specified authorities) when there is detected a container based threat (optionally though multiple communications networks).   Accurate, real time position data on the container   The composite door can be fitted to new or retro fitted to existing containers   The electronic sensors and antennas are tamper-proof because they are located internally in the door.   Accurate, real time position data on the container   More permeability to X-Rays means significant reductions in power requirements and hence costs for port side inspection equipment. This in turns means availability of equipment can be higher and through put significantly improved.   The system is also upgradable to include RFID operations for automation of the manifest management at a container level, building, checking, downloading of the manifest and per container stock control       
 
         [0051]    For existing metal shipping containers, the container door is replaced with a composite one which is substantially transparent to Radio Frequency (RF). Tracking and sensing electronics to detect door opening, Volatile Organic Compounds (VOC), radioactive devices, stowaways and container movement would be encapsulated in the door, thus greatly improving security. The composite door is also more permeable to the X-rays than conventional doors due to its RF transparency. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0052]    Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings in which: 
           [0053]      FIG. 1  is a view of a shipping container incorporating an embodiment of the present invention; 
           [0054]      FIG. 2  is a view of a shipping container incorporating an alternate embodiment of the present invention; 
           [0055]      FIG. 3  is a perspective view of a door according to an embodiment of the present invention; 
           [0056]      FIGS. 4   a  to  4   k  are views of various aspects of the door of  FIG. 3 ; 
           [0057]      FIGS. 5 to 7  are schematic diagrams of aspects of implementations of a tracking and monitoring system according to embodiments of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0058]      FIG. 1  is a view of a shipping container incorporating an embodiment of the present invention.  FIG. 2  is a view of a shipping container incorporating an alternate embodiment of the present invention. 
         [0059]      FIG. 1  differs from  FIG. 2  in that both doors in  FIG. 1  are formed in accordance with embodiments of the present invention whereas in  FIG. 2  one conventional door is used alongside a door according to an embodiment of the present invention. 
         [0060]    In embodiments of the present invention, doors may optionally include embedded electronic systems. Where two doors are used as in  FIG. 1 , one of the doors,  10 , may include the electronic systems and the other,  20 , is may optionally be formed in the same manner but with electronics omitted. 
         [0061]    While both doors may include electronics systems such as communication and sensory components, this is not necessary and advantageous results can be achieved by having the electronics systems in one RF transparent door and extending the RF transparency to the whole door area by also having the other door RF transparent. Alternatively, only one door of a pair may be formed in accordance with an embodiment of the present invention and the other from conventional materials. 
         [0062]    As each door  10  according to an embodiment of the present invention is substantially transparent to radio frequency waves, it enables the integration of electronic systems which can communicate with components inside a container and also with systems external to the container. The electronics systems may include antennae. They are preferably integrated and encapsulated inside the composite door making them robust, invisible and physically inaccessible yet still able to communicate with entities both inside and outside of the container when the doors are closed and the container is secure. It will be appreciated that this offers significant security advantages over systems where the antennae and electronics are mounted inside or outside the container. 
         [0063]    The type of composite used is preferably an E-glass/polyester. A central core, preferably of a plywood panel, is sandwiched between E-glass fibre layers. It will be appreciated that the core may be encased by a single moulded or formed layer rather than two separate sandwich layers if desired. Similarly, multiple sandwich layers could be used. 
         [0064]    The composite door preferably acts as a radome for the electronic communications devices. E glass/polyester has a relative dielectric constant of 6.1 and gives sufficient RF transmittance for this application. 
         [0065]    The glass fibre based composite material together with a high quality manufacturing method enables manufacturing of laminates with good radome characteristics. The radome is preferably made from a single laminate and has a constant thickness with tolerances of around±0.2-0.5 mm. 
       Properties of E-Glass 
       [0066]      
         [0000]    
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 Density [g/cm3] 
                 2.58 
               
               
                   
                 Youngs modulus [GPa] 
                 72 
               
               
                   
                 Dielectric constant [—] 
                 6.1 
               
               
                   
                 Refractive index [—] 
                 1.558 
               
               
                   
                 Price estimate [Euro/kg] 
                 2-6 
               
               
                   
                   
               
             
          
         
       
     
         [0067]    The composite is preferably coated with UV protective layer such as a Gel-coat, pigmented polymer layer to protect against UV radiation from sunlight and the like that could otherwise cause the composite to degrade. This outer layer is preferably applied during the manufacturing process. The gel-coat is arranged such that it does not contribute to the mechanical properties of the radome, instead it merely serves as a protective layer and coloured surface which can be printed on if required. 
         [0068]    The frame of the composite door is preferably made from U-profile steel which is cut into shape such as by use of a laser cutter. 
         [0069]    The production of the door can optionally be divided in three sections:
       1. Production for storage (prior to container specifications)   2. Production for specific container   3. Retro-fit of container door       
 
       Production for Storage 
       [0073]    The plywood core for the door can be machined and routed for the largest container and later cut to size and used for all types and sizes of door as shown in  FIG. 4   a . The thickness of the door should preferably be the same for all types on the market. 
         [0074]    The glass fibre and resin of one or both of the first and second layers ( FIG. 4   b ) can be added to form the composite sandwich and the door saved in storage awaiting orders. 
         [0075]    The frame ( FIG. 4   c ) for the door is stored as a specified u-profile uncut. The profile will preferably be the same for all types of containers. 
         [0076]    Hinges and lock bars can be ordered at the time of purchase of a retro-fit door or alternatively, a stock of the mostly used types can be held. It will be appreciated that unlike with steel doors, the materials used in a container door of the type described above lend themselves particularly well to manufacture and sizing to order. Door blanks can be held in stock and trimmed to meet the sizing needs of the particular order. 
         [0077]    It will also be appreciated that the ordering system can enable flexibility of components to be included in the door. For example, type and positioning of hinges and lock bars can be varied. Additionally, the type of electronic systems and communication systems and antennae can be selected during the ordering and manufacture process such that the door can truly be made to measure in terms of both size and functionality. 
       Production for Specific Container 
       [0078]    When the specific dimensions of the container door have arrived the components can be adjusted. 
         [0079]    The composite panel can then be cut to the dimensions needed ( FIG. 4   d ). 
         [0080]    After cutting, the front is routed for the steel frame and lock bars to fit ( FIG. 4   e ). 
         [0081]    The panels are now ready for door assembly. 
         [0082]    The steel frame is optionally laser cut for cheap and fast production from the steel profile. The steel frame is preferably closely fitted, welded at the corners and optionally bolts are used for tightening purposes. 
         [0083]    The door is then assembled with all the components including the electronics systems as shown in  FIGS. 4   g  and  4   h.    
         [0084]    Finally the hinges and lock bars are fastened before the door is shipped for retro-fitting as shown in  FIGS. 4   i  to  4   k.    
         [0085]    It will be appreciated that doors may be specified as parts of new containers or they could be retro-fitted to existing containers. 
         [0086]    To make the retro-fitting as simple as possible, dimensions are selected to be as close to the original container as possible. In order to retro-fit the composite door, existing hinge pins are cut at the door frame of the container and the replacement door is fitted by welding new hinge pins to the frame. 
         [0087]    The new door is delivered with new hinges, lock bars and rubber seals already in situ. 
         [0088]    With the door design adjusted for each container retro fit time is the minimum possible. 
         [0089]    To enable easy X-raying of the container, two composite doors can be fitted making substantially the whole door area transparent to radio frequency transmission as shown in  FIG. 1 . 
         [0090]    Preferably, the electronics systems include a ZigBee node that is encapsulated within the door. As will be appreciated, Zigbee enables a peer-to-peer style of wireless mesh network to be formed. The Zigbee node forms a mesh network with other container ZigBee nodes in the vicinity. This will ensure reliable communication paths can be established out of stacks of containers. 
         [0091]    Embodiments of the present invention may be used in varying situations as shown in  FIG. 5 . Preferably, the system will be operated in the following modes dependent on the location of the shipping container.
       Container stored in the container yard at the port ( 100 )   Container is located onboard a ship ( 110 )   Container transported overland onboard a truck ( 120 )   Container lost in area with no ZigBee communication       
 
         [0096]    When the container is placed on the quayside or in the container yard at the port, communication will be via a ZigBee mesh network operated to communicate information relating to the contents and status of the container to the owner of the cargo, the Port Administration, Ship-owner or the appropriate authority. Communications may be to a suitable WiFi or GSM type network  130  or via a satellite link  140  via an intermediate bridge between the ZigBee network and the other communications network  130 / 140  to a client  150  for monitoring, reporting, status checks etc. 
         [0097]    When the container is placed on a containership, another ZigBee meshing network will be operational. ZigBee routers in this situation may be installed at strategic positions on the ship to enable communication with containers stored in the hold. These will all be linked to a ZigBee coordinator installed in a location such as on the bridge of the ship. It is proposed that the coordinator will transmit information to the relevant parties via a satellite beacon fitted to the ship. Information could, for example, be sent to a control centre via the Iridium satellite. 
         [0098]    Note that there will be a switch over point between the ZigBee coordinator on the bridge of the ship and the coordinator installed in the port office. This will be done by measuring the receiver signal strength (RSSI). The router will link to the coordinator with the highest signal strength. 
         [0099]    When the container is being transported overland on a truck, communication will be via a GSM/GPRS/Satellite network and it will be tracked by using GPS. Suitable electronic components may be integrated into the door to enable GSM or indeed another mobile telephony type communication and/or GPS triangulation. Alternatively or in addition, a gateway may be provided on the lorry that can be accessed via ZigBee and provide a proxy access to other communication networks. 
         [0100]    A modular approach is used in the design and configuration of doors and included electronics systems in order to allow doors to be tailored to the requirements of the end users. For example, one user may require a fully configured solution with a door populated with redundant antennae, all possible communications and sensor types whereas another may only require a sub-equipped system. 
         [0101]    The ZigBee system may include a ZigBee router node encapsulated in each composite container door. The composite door will preferably act as a Radome which will be transparent to radio frequency transmission. The monitoring system of embodiments of the present invention also preferably includes a ZigBee coordinator positioned on the bridge of containerships and in the port control office. Coordinators receive information from the ZigBee mesh network connecting the container nodes. The ZigBee system will preferably operate at a frequency of 2.4 GHz 
         [0102]    All data from the Zigbee system (dock and ship) and the GSM/Satellite system (overland) is communicated to a central system at which it is collected and stored centrally on a database, allowing remote access to view the status of the container. 
         [0103]      FIG. 6  is a block diagram illustrating systems that may be operational depending on use. When operating overland or at a port, GSM  210  and GPS  220  systems communicate with the communications system  200  of the door  10 . When on ship, GPS  220  and satellite links  230  may be used. 
         [0104]      FIG. 7  is a block diagram showing aspect of possible combinations of electronics components of the door of embodiments of the present invention in more detail. The components may include: 
         [0105]    A communication system  200  (which may include ZigBee, GSM, GPS and/or other communication system functions);
   A processor  300  arranged to interface with sensors  330 , the communications system  200 , a real time clock  360  and a memory  350 ;   A controllable lock  310 ;   An RFID tag  320 ;   Sensor(s)  330  and sensor support components such as an air sampling fan;   A power supply  340  (which may be battery or from a supply source);   A memory  350  for use in storing data on the container, sensor readings, alarm states and over time etc;   A real time clock  360 .   
 
       Sensor System 
       [0113]    As indicated above, doors may preferably include electronics systems for monitoring the container. In one embodiment, miniature fans are embedded in the interior side of the door to enable intake of air from inside the shipping container for passing to sensors embedded in the door for taking measurements. The sensors are preferably located in close proximity to the fans in order to maximise this effect. Each fan preferably operates for a few seconds on system start-up; this is sufficient time for measurements to be taken. This will also help with the conservation of the system battery supply. 
         [0114]    The sensors are preferably located in the upper half of the container door and can be easily changed if a fault occurs. Additionally the system can be enhanced by the fitting of other sensors for sensing substances appropriate to the intended application. 
         [0115]    The following sensors are examples that may be integrated into the composite door:
   CO2 sensor:—for sensing stowaways.   VOC sensor:—to detect Volatile Organic Compounds (VOC)—This may be, for example, a heated wire sensor   Radiation sensor:—to detect materials that could be used in a “Dirty Bomb”. The sensor module may use a “none tube” radiation sensor based on a Silicon photo multiplier device. This is connected to a charge pump circuit to show radioactive signatures.   Door switch:—intruder detection. For example, the sensor may be a switch located on a latch or frame of the door and is arranged to send an alarm upon detecting the door opening.   Vibration sensor:—to detect movement of the container. For example, a Piezo device may be set so that when a movement with enough force vibrates the device, an alarm signal is sent to the microcontroller.   
 
         [0121]    Note that because the system has a modular design, other sensor types can be fitted as required. Other types of sensors could be integrated to detect different types of gas, for example. It will also be appreciated that although wireless networks such as ZigBee and GSM are discussed, other network types could be used to provide communication functionality. Whilst it is preferred that an ad-hoc mesh type network is used to provide communications from individual containers, other short or long range wireless communication systems could equally be employed either for container to local controller/router communications or indeed to provide direct access to a container via long range communication systems. 
         [0122]    The system is preferably powered by batteries which are replaceable. They are preferably located behind a tamper-proof panel on the inside of the door. Optionally, alternate energy systems such as solar power could be integrated to supplement or replace batteries. The batteries could also be re-chargeable via a suitable coupling or optionally via a technology such as inductive charging. 
         [0123]    As well as using the system in ISO container types for eCommerce and security, embodiments of the present invention may be adapted to be used in other container or mobile bodies with doors such as refrigeration or curtain sided trucks, baggage transporter containers in airports, air-freight shipping containers and the like. 
         [0124]    As a commercial/eCommerce application, and as opposed to the security uses, auto reading of RFID tagged items going onto a container would enable instantaneous electronic documentation to be produced for manifesting, stock control etc. and could also generate an alarm the instant any item was unexpectedly removed from a container, thus dramatically reducing the risk of theft. 
         [0125]    The research/work leading to these results has received funding from the European Union&#39;s Seventh Framework Programme (FP7/2007-2013) under Grant Agreement no 218414-2.