WO2008054365A2

WO2008054365A2 - Accelerometer controlled security container device

Info

Publication number: WO2008054365A2
Application number: PCT/US2006/034788
Authority: WO
Inventors: Stig EKSTRÖM
Original assignee: Ge Security, Inc.
Priority date: 2006-07-27
Filing date: 2006-09-08
Publication date: 2008-05-08
Also published as: WO2008054365A3

Abstract

A container security device (CSD) can be mounted near a container door and doorframe such that the device, using a sensor, can measure a distance between the door and the doorframe. By measuring and comparing this distance measurement with one or more alarm limits, the CSO can determine if the door is open and, if so, activate an 10 alarm. Because of design and manufacturing tolerances, container doors can move relative to the doorframe while the container is in transport. Because of this movement, 'tighter' alarm limits can be applied when the container is stationary than when the container is moving. The CSD comprises an accelerometer which can detect at least some movement of the container. Based on measurements from the accelerometer, the 15 CSD can characterize the container as 'moving' or 'stationary' and can select the corresponding alarm limits from a set of alarm limits.

Description

USING AN ACCELEROMETER TO SET ALARM LIMITS IN A CONTAINER

SECURITY DEVICE

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application No. 60/820,580, titled "USING AN ACCELEROMETER TO SET ALARM LIMITS IN A CONTAINER SECURITY DEVICE" and filed July 27, 2006, which is incorporated herein by reference.

FIELD

This disclosure relates to devices for securing containers, including freight containers.

BACKGROUND

Goods are often shipped in containers suitable for use in several different modes of transportation. Such containers are commonly known as "intermodal" freight containers. It is often desirable, e.g., for security reasons, to monitor the condition of freight containers or other containers. A condition to be monitored can include whether a door of the container has been opened, and this condition can be determined in part by measuring the distance of the container door from the container doorframe.

A container security device (CSD) can be used to monitor conditions in a container, e.g., whether a container door has been opened. However, many CSD's currently available can provide imprecise measurements under some container conditions, and this imprecision can be exploited to circumvent a CSD.

SUMMARY

A CSD can be mounted near a container door and doorframe such that the device can measure a distance between the door and the doorframe. By measuring and comparing this distance measurement with one or more alarm limits, the CSD can determine if the door is open and, if this is the case, activate an alarm. The CSD can comprise an accelerometer or similar sensing device which can detect at least some movement of the container. Based on measurements from the accelerometer, the CSD can characterize the container as "moving" or "stationary" and can select alarm limits from a set of alarm limits. Distance measurements can be evaluated according to "moving alarm limits" if the container is characterized as moving, or the measurements can be evaluated according to "stationary alarm limits" if the container is characterized as stationary.

In one embodiment, a container monitoring device for monitoring a container with a door comprises a sensor for detecting a position of the door and providing sensor readings, an accelerometer for providing accelerometer readings, and a processor. The processor is configured to select, based at least in part on the accelerometer readings, one or more alarm limits from a set of alarm limits, and to evaluate the position of the door according to the sensor readings and according to the one or more selected alarm limits. The set of alarm limits can comprise a set of stationary alarm limits and a set of moving alarm limits. In another embodiment, the processor is configured to select the set of stationary alarm limits based on a first set of accelerometer readings and to select the set of moving alarm limits based on a second set of accelerometer readings. The processor can be configured to indicate an alarm condition according to the evaluation. The processor can also be configured to calculate an average accelerometer reading. The container monitoring device can also comprise one or more filters configured to filter the accelerometer readings. The accelerometer can be a 3-axis accelerometer. In some embodiments, the sensor is configured to detect a distance between the door of the container and a doorframe of the container. The container can be a shipping container. The processor can be configured to activate the accelerometer based at least in part on the position of the door.

In an additional embodiment, a method of monitoring a container with a door can comprise obtaining door sensor readings, obtaining accelerometer readings, selecting one or more alarm limits from a set of alarm limits according to the accelerometer readings, and evaluating the door sensor readings according to the selected alarm limits. The door readings can comprise an approximate distance between the door and a container door frame. One embodiment of the method also comprises indicating an alarm condition as a result of the evaluation. Another embodiment of the method also comprises filtering the accelerometer readings. The accelerometer readings can be obtained as a result of obtaining the door sensor readings.

In yet another embodiment, a computer-readable medium contains instructions which can cause a method to be performed. The method can comprise obtaining door sensor readings for a door of a shipping container, obtaining accelerometer readings for the shipping container, and selecting one or more alarm limits from a set of alarm limits according to the accelerometer readings. The method can also comprise evaluating the door sensor readings according to the selected alarm limits, and possibly indicating an alarm condition as a result of the evaluation. The set of alarm limits can comprise moving alarm limits and stationary alarm limits. The door sensor readings can correspond to a distance between the door of the container and a doorframe of the container

Disclosed below are representative embodiments of materials and structures for a CSD. Also described are exemplary methods for making such materials and structures, and exemplary environments and applications for the disclosed embodiments. The described materials and structures, and methods for making and using such materials and structures, should not be construed as limiting in any way. Instead, the present disclosure is directed toward all novel and nonobvious features, aspects, and equivalents of the various disclosed embodiments, alone and in various combinations and sub-combinations with one another. The disclosed technology is not limited to any specific aspect, feature, or combination thereof, nor do the disclosed materials, structures, and methods require that any one or more specific advantages be present or problems be solved. For the sake of simplicity, the attached figures may not show the various ways in which the disclosed apparatus and methods can be used in conjunction with other systems, methods, and apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. IA is a diagram illustrating communication among components of one embodiment of a container monitoring system.

Fig. IB is a diagram illustrating an exemplary supply chain.

Fig. 2A is a schematic block diagram of one embodiment of a container security device (CSD).

Fig. 2B is a schematic block diagram of one embodiment of a printed circuit board assembly (PCBA) of the CSD.

Fig. 2C is a perspective drawing of one embodiment of a CSD with a partial cutaway of molding material.

Fig. 2D is a perspective drawing of the CSD of Fig. 2C, turned upside down, with a partial cut-away of molding material.

Fig. 2E is a front view of one embodiment of a CSD without molding material.

Fig. 2F is a bottom view of one embodiment of a CSD without molding material.

Fig. 2G is a front view of one embodiment of a CSD.

Fig. 2H is a back view of one embodiment of a CSD.

Fig. 21 is a bottom view of one embodiment of a CSD.

Fig. 2J is a top view of one embodiment of a CSD.

Fig. 2K is a front view of a CSD installed on a container.

Fig. 2L is a perspective view of the device of Fig. 2K.

Fig. 3 A is a schematic diagram of one embodiment of a reader.

Fig. 3B is a perspective drawing of one embodiment of a reader.

Fig. 4 is a diagram showing a first application scenario of the system of Fig. IA.

Fig. 5 is a diagram showing a second application scenario of the system of Fig. IA.

Fig. 6 is a third application scenario of the system of Fig. IA.

Fig. 7 is a fourth application scenario of the system of Fig. 1 A.

Fig. 8 is a diagram illustrating a container securing process.

Fig. 9 is a diagram illustrating a container status check process. Fig. 10 is a flowchart of one embodiment of a method for using a CSD to monitor a container.

Fig. 11 is a flowchart of one embodiment of a method for determining which alarm limits to use in a CSD.

DETAILED DESCRIPTION

Exemplary Container Monitoring System

Fig. IA shows components of one embodiment of a system 1 for monitoring containers, including shipping containers. The system 1 comprises a container security device (CSD) 12, at least one variety of a reader 16, a server 15, and a software system 17. The CSD 12 can determine if the container 10 has been breached (e.g., if the container door has been opened) after the container 10 has been secured. A secured container 10 can be tracked by a reader 16. Reader 16 can comprise hardware and/or software for communicating with the server 15, perhaps wirelessly, or perhaps using a cable for downloading data to a PC that transmits the data over the Internet to the server 15. Various conventional means for transmitting the data from the reader 16 to the server 15 can be implemented within the reader 16 or as a separate device. In various embodiments, the reader 16 can be configured as a handheld reader 16(A), a mobile reader 16(B), or a fixed reader 16(C). The handheld reader 16(A) can be, for example, operated in conjunction with, for example, a mobile phone, a personal digital assistant, or a laptop computer. The mobile reader 16(B) is basically a fixed reader with a GPS interface, typically utilized in mobile installations (e.g., on trucks, trains, or ships using existing GPS, AIS or similar positioning systems) to secure, track, and determine the integrity of the container in a manner similar to that of the hand-held reader 16(A). In fixed installations, such as, for example, those of a port or shipping yard, the fixed reader 16(C) can be installed on a crane or gate. The reader 16 can serve primarily as a relay station between the CSD 12 and the server 15.

The server 15 can store a record of security transaction details such as, for example, door events (e.g., security breaches, container security checks, securing the container, and disarming the container), container location, as well as any additional desired peripheral sensor information (e.g., temperature, motion, radioactivity). The server 15, in conjunction with the software system 17, can be accessible to authorized parties in order to determine a last known location of the container 10, make integrity inquiries for any number of containers, or perform other administrative activities.

In one embodiment, the CSD 12 can be configured to communicate with the readers 16 via a short-range radio interface such as, for example, a radio interface utilizing direct-sequence spread-spectrum principles. The radio interface can use, for example, Bluetooth or any other short-range, low-power radio system that operates in the license-free Industrial, Scientific, and Medical (ISM) band, which operates at approximately 2.4 GHz. Depending on the needs of a specific solution, various radio ranges can provided, such as, for example, a radio range of up to about 100 m. In other embodiments, longer or shorter ranges can also be provided. In another embodiment, the CSD 12 can be configured to communicate with the readers 16 via a cable or direct connection.

The readers 16 can communicate via a network 13, e.g. using TCP/IP, with the server 15 via a wireless technology (e.g., Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications (GSM), Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Pacific Digital Cellular System (PDC), Wideband Local Area Network (WLAN), Satellite Communications systems, Automatic Identification Systems (AIS), or Mobitex), or via a wired technology such as a Local Area Network (LAN). The server 15 can communicate with the software system 17 via a suitable wired or wireless technology. The software system 17 can be configured to support real-time surveillance services such as, for example, tracking and securing of the container 10 via the server 15, the readers 16, and the CSD 12. The server 15 and/or the software system 17 can be adapted to store information such as, for example, identification information, tracking information, door events, and other data transmitted by the CSD 12 and by any additional peripheral sensors interoperably connected to the CSD 12. The software system 17 can also allow access, for authorized parties, to the stored information via a user interface that can be accessed via, for example, the Internet.

Exemplary Container Transportation System

Fig. IB shows a diagram illustrating a flow 2 of an exemplary supply chain from points (A) to (I). Referring first to point (A), a container is filled with cargo by a shipper or the like. At point (B), the loaded container is shipped to a port of embarkation via highway or rail transportation. At point (C), the container is gated in at the port of loading such as a marine shipping yard.

At point (D), the container is loaded on a ship operated by a carrier. At point (E), the container is shipped by the carrier to a port of discharge. At point (F), the container is discharged from the ship, loaded onto a truck and gated out of the port of discharge at point (G). At point (H), the container is shipped via land to a point (I), where the container is unloaded by a consignee.

There can be many times within the points of the flow 2 at which security of the container can be compromised without visual or other conventional detection. In addition, the condition of the contents of the container can be completely unknown to any of the parties involved in the flow 2 until point (H) when the contents of the container are unloaded.

Exemplary Embodiment of Sensing Device

Fig. 2A is a block diagram of one embodiment of the CSD 12. In one embodiment, the CSD 12 comprises an antenna 20, an RF/baseband unit 21, a printed circuit board assembly (PCBA) 220, and a door sensor 29. The CSD 12 can also comprise an interface 28 for attaching additional sensors to monitor various internal conditions of the container such as, for example, temperature, vibration, radioactivity, gas detection, and motion. The CSD 12 can further comprise an optional power source 26 (e.g., battery); however, other power arrangements that are detachable or remotely located can also be utilized by the CSD 12. In embodiments where power source 26 comprises a battery, inclusion of the power source 26 inside the CSD 12 can help prolong battery life by at least partially insulating the power source 26 from temperature fluctuations. The presence of the power source 26 within the container 10 can also reduce opportunities for tampering with or damaging the power source 26. In another embodiment, the CSD 12 can also comprise a connector (not shown) for interfacing directly with the reader 16. For example, a connector can be located on an outer wall of the container 10 for access by the reader 16. The reader 16 can then connect via a cable or other direct interface to download information from the CSD 12.

Fig. 2B is a block diagram of one embodiment of the PCBA 220. PCBA 220 comprises a microprocessor unit (MPU) 221 and a memory 222, which can be, for example, RAM, ROM, or another computer-readable medium as is known in the art. The memory 222 can store software instructions and other data. PCBA 220 can further comprise: an analog-digital converter (ADC) 223; one or more filters 224; and an accelerometer 225. Accelerometer 225 is preferably a 3 -axis accelerometer, but in some embodiments a 1 - or 2-axis accelerometer can be used. Appropriate accelerometers can be obtained from, for example, STMicroelectronics, Inc., Geneva, Switzerland, and Analog Devices, Inc., Norwood, Massachusetts. Examples of suitable accelerometers from these sources are the model number LIS302ALB from STMicroelectronics and the model number ADXL33O from Analog Devices. As is further explained below, the accelerometer 225 can indicate whether a container 10 is moving. Filters 224 can comprise analog or digital filters implemented in hardware, software or a combination thereof. Embodiments using digital filters can be configured to convert analog inputs (e.g., from the accelerometer 225) into digital inputs using the ADC 223.

In one embodiment, the filters 224 comprise a hardware filter and a software filter. The software filter can be implemented according to instructions stored in the memory 222. In another embodiment, a signal from the accelerometer 225 is sampled at a relatively low frequency (e.g., at about 8 Hz) and sent through a low-pass filter. This can save power in comparison with an embodiment that samples and filters an accelerometer signal at a higher frequency. Filters 224 can be configured for use in obtaining mean values of signals from the sensor 29 and the accelerometer 225. Passing the accelerometer signal through a low-pass filter (LPF) can remove high- frequency accelerometer signals that are not necessarily indicative of container movement. For example, banging on the side of the container 10 could result in high- frequency accelerometer signals, even if the container 10 as a whole is stationary. The cutoff frequency for the LPF can be set as desired. In some embodiments, this LPF is a short, fast filter. In other embodiments, a slower LPF can filter the accelerometer output to provide a stable reference accelerometer output value.

Those of skill in the art will recognize different embodiments in which components comprising PCBA 220 can be integrated with each other or with additional components to various degrees. For example, in one embodiment, all or most of the components of PCBA 220 are separate physical components, whereas in another embodiment all or some of the components are integrated into one physical component. For example, ADC 223 can be integrated into the MPU 221 (as shown in Fig. 2B).

The MPU 221 can recognize one or more door events received from the reader 16, the events comprising, for example, requests to arm or disarm the container, and requests to report the status or identity of the container. The door events can also comprise events based on information from the door sensor 29, such as opening of a door after the container 10 has been secured. In one embodiment, the door events can be time-stamped and stored in the memory 222 for transmission to the reader 16. The door events can be transmitted immediately, periodically, or in response to an interrogation from the reader 16. The door sensor 29 can be, for example, a magnetic sensor, a pressure sensor, an alternative contact sensor, a proximity sensor, or any other suitable sensor for detecting relative movement between two surfaces.

The antenna 20 can be provided for data exchange with the reader 16. Various information, such as, for example, status and control data, can be exchanged. In one embodiment, the MPU 221 (or another component of PCBA 220, such as memory 222) can be programmed with a code that uniquely identifies the container 10. In one embodiment, the code is an International Standards Organization (ISO) container identification code. The MPU 221 can also store other logistic data, such as Bill-of- Lading (B/L), a mechanical seal number, a reader identification with a time-stamp, etc. A special log file can be generated, so that a tracking history, together with door events, can be recovered. The code can also be transmitted from the CSD 12 to the reader 16 for identification purposes. In one embodiment, for transmission the RF/baseband unit 21 can upconvert microprocessor signals from baseband to RF for transmission to the reader 16.

In another embodiment, the CSD 12 can be configured, via the antenna 20, to receive a status report request from the reader 16. In response to the request, the MPU 221 can access the memory 222 to extract, for example, door events, temperature readings, security breaches, or other stored information in order to send the extracted information to the reader 16. The reader 16 can also send an arming or disarming request to the CSD 12. In one embodiment, when the container 10 is secured (i.e., armed) according to a request by the reader 16, the MPU 221 can be programmed to emit an audible or visual alarm when the door sensor 29 detects a material change in readings (e.g., a material change in the distance between the sensor and the door surface). The CSD 12 can also log the change in the memory 222 for transmission to the reader 16. If the reader 16 sends a disarming request to the CSD 12, the MPU 221 can be programmed to disengage from logging door events or receiving signals from the door sensor 29 or other sensors interoperably connected to the CSD 12.

Power Management

In one embodiment, the MPU 221 can be programmed to implement power- management techniques for the power source 26 to reduce power consumption. One option is that one or more time windows can be specified (e.g., via the antenna 20) for activation of the components in the CSD 12. Outside the specified time windows, the CSD 12 can be placed in a "sleep mode" to reduce power consumption. Such a sleep mode can account for a significant part of the device operation time, and the CSD 12 can as a result be operated over an extended period (e.g., several years) without a battery replacement.

During the sleep mode, a portion of the circuitry of the CSD 12 (e.g., components of PCBA 220) can be switched off. For example, in one embodiment most circuitry can be switched off except for the door sensor 29 and a time measurement unit (e.g., a counter in the MPU 221) that measures a sleep time period t_sι_eep. When the sleep time period has expired or when the door sensor 29 senses a door event, the remaining circuitry of the CSD 12 can be powered up.

When the CSD 12 receives a signal from the reader 16, the CSD 12 can remain active to communicate with the reader 16 as long as necessary. If the CSD 12 does not receive a signal from the reader 16, the CSD 12 will stay active as long as necessary to ensure that no signal is present during a time period referred to as a radio-signal time period or "sniff period" (%„,//'). After the period /^lapses, the CSD 12 can be powered down again, except for the time measurement unit and the door sensor 29, which operate to wake the CSD 12 up again after either a door event has occurred or another sleep time period has expired.

In one embodiment, the radio-signal time period t_smff is much shorter (e.g., by several orders of magnitude) than the sleep time period t_sι_eep. This can prolong the lifetime of the power source 26 and the CSD 12 (e.g., by several orders of magnitude) relative to an "always on" scenario, in which all or most components of CSD 12 remain active.

The sum of the sleep time period and the reader-signal time period (which can be known as the "cycle time") can be used as a lower limit on the time period that can elapse to increase the chance that the reader 16 becomes aware of the presence of the CSD 12. In this description, the sum of the sleep time period and the sum of the cycle time is called the passing time ("t_pass").

In some embodiments, a passing time is dictated by the particular situation. For example, the passing time can be very long in certain situations (e.g., many hours when the CSD 12 on a freight container is communicating with the reader 16 on a truck head or chassis carrying the container 10) or very short in other situations (e.g., fractions of a second when the CSD 12 on the container 10 is passing by the fixed reader 16(C) at high speed). Typically, a device 12 will, during its lifetime, sometimes be in situations with a greater passing time and sometimes be in situations with a lesser passing time. Accordingly, in some embodiments the sleep time period can be selected such that the sleep time period is compatible with a shortest conceivable passing time (%_αss,min")- In other words, t_sι_eep ≤tpass,mm-t_Smff- Sleep time periods can be assigned to the device in a dynamic matter depending on the particular situation of the device.

In one embodiment, when the reader 16 communicates with the CSD 12, the reader 16 reprograms the sleep time period of the CSD 12 based at least in part on the location and function of the reader 16, data read from the CSD 12, or other information that is available in the reader 16. In one example, the container 10, equipped with the CSD 12, is located on a truck by a toplifter, straddle carrier, or other suitable vehicle. The suitable vehicle is equipped with the reader 16, whereas a truck and trailer are not equipped with any readers 16. The truck can drive at a relatively high speed (or, in other embodiments, at a relatively low speed) past the fixed reader 16(C). In this situation, the reader 16(C) on the vehicle preferably programs the CSD 12 with a short sleep time period (e.g., about 0.5 seconds).

In other embodiments, depending on the situation, the reader 16 can program sequences of sleep periods into the CSD 12. For example, when the container 10 is loaded onboard a ship, it can be sufficient for the CSD 12 to wake up once an hour while the ship is at sea. However, when the ship is expected to approach a destination port, a shorter sleep period can be used to help ensure that the reader 16 on a crane unloading the container 10 will be able to establish contact with the CSD 12. For example, the reader 16 on the crane loading the container 10 onboard the ship can program the CSD 12 as follows: first, wake up once an hour for three days, then wake up every ten seconds.

In another embodiment, the reader 16 can be configured to move together with the CSD 12 and modify the sleep time period according to the geographical location of the device 12. For example, the CSD 12 on the container 10 and the reader 16 of a truck towing the container 10 can be configured to constantly communicate with each other while the container 10 is being towed. While the container 10 is a predetermined distance from its destination, the reader 16 could program the CSD 12 to be asleep for extended intervals (e.g., one hour). The reader 16 can be equipped with a Global Positioning System (GPS) receiver or other positioning equipment and determine when the container 10 is approaching its destination. Once the container approaches the destination, the reader 16 could program the CSD 12 to wake up more frequently (e.g., every second).

While the above-described power-management method has been explained with respect to the CSD 12 in the context of trucking of freight containers or other cargo in transportation by sea, road, rail or air, the above-described power-management method can also be applied to, for example, trucking of animals, identification of vehicles for road toll collection, and theft protection, as well as stock management and supply chain management.

Exemplary Embodiment of Sensing Device

Fig. 2C shows a first perspective view of one embodiment of the CSD 12. The CSD 12 comprises a housing 25 containing a data unit 100 (see, e.g., Fig. 2L), a support arm 102 extending therefrom, and an antenna arm 104 extending outwardly thereof in an angular relationship therewith. As will be described below, the size of the housing 25, the length of the support arm 102, and the configuration of the antenna arm 104 can be selected for compatibility with one or more containers. The housing 25, the support arm 102, and the antenna arm 104 can be molded within a polyurethane material 23 or the like in order to provide protection from the environment.

In this view, a portion of material 23 of the support arm 102 is cut away to illustrate placement of at least one magnet 27 therein and at least one door sensor 29 thereon. The magnet 27 can permit an enhanced securement of the CSD 12 within the container as described below, while the door sensor 29 detects variations in pressure along a sealing gasket (not shown) of the container discussed below. Other methods of securing the device 12 within the container 10 (e.g., adhesives, screws) can also be used.

Fig. 2D shows a second perspective view of the CSD 12 and further illustrates the placement of the magnet 27 in the support arm 102. In one embodiment, the magnet 27 can be positioned within corresponding apertures 27A formed in the support arm 102 and can be bonded thereto in a manner facilitating the installation of the CSD 12. Fig. 2E shows a top view of the CSD 12 without molding material 23. The CSD 12 comprises the data unit 100, which can comprise the power source 26, the PCBA 220 (not shown) and the interface 28. In the depicted embodiment, the support arm 102 extends from the data unit 100 and comprises the apertures 27 A to house the at least one magnet 27 as well as a support surface to which the door sensor 29 is attached. Extending from the support arm 102 is the antenna arm 104 for supporting the antenna 20.

Fig. 2F depicts a bottom view of the CSD 12 without molding material 23. As shown, the support arm 102 extends upwardly and outwardly from the data unit 100. The support arm 102 can be relatively thin and substantially horizontal, although other configurations are available. The antenna arm 104 can be configured to extend angularly from the support arm 102.

Fig. 2G shows a front view of the CSD 12 with the molded material 23 that forms the housing 25 encapsulating the CSD 12. In the depicted embodiment, the molding material 23 extends from the antenna arm 104 across the support arm 102 and around the data unit 100. The particular shape and configuration shown herein is but one embodiment of the CSD 12, and other shapes are possible.

Fig. 2H shows a back view of the CSD 12. Figs. 21 and 2J show bottom and top views of the CSD 12, respectively.

Fig. 2K illustrates a front view of the CSD 12 as installed on one possible container 10. The container 10 is shown with a door 202 of the container 10 in an open position, illustrating the orientation of the CSD 12 in greater detail. The CSD 12 is mounted to an area of the container 10 adjacent to the door 202, for example, on a vertical beam 204 of the doorframe of the container 10. As can be seen in Fig. 2K, the CSD 12 can be mounted so that when the door 202 is closed: the antenna arm 104 is located on the exterior of the container 10; the door sensor 29, located within the support arm 102, is directly adjacent to a portion of the door 202; and the data unit 100 is located on the interior of the container 10. The CSD 12 can detect, via the door sensor 29, deviations of pressure to determine whether a door event (e.g., a change in relative and/or absolute distance between the door and the doorframe) has occurred. Some possible methods of determining a door event are described in more detail below. The CSD 12 can transmit data relating to the status of the door 202 via the antenna 20 to the reader 16 as described above. In some embodiments, the interface 28 can be connected to one or more external sensors 208 in order to capture information relative to internal conditions of the container 10. This information can also be transmitted to the server 15.

In the depicted embodiment the CSD 12 is oriented within the container 10 so that the data unit 100 is disposed within a generally C-shaped recess or channel 206. The support arm 102, including the door sensor 29, extends across the vertical beam 204 between it and a portion of the door 202. Generally, when the door 202 is closed, a distance between the door 202 and the vertical beam 204 is maintained at the door sensor 29, and when the door 202 is opened, the distance changes. The change in distance can cause the PCBA 220 to determine that the container has been breached, and an electronic security key stored in the memory 222 can be erased or changed to indicate a "broken" seal or breach.

Fig. 2L is a perspective view of the CSD 12 of Fig. 2C as installed on the container 10. The CSD 12 is shown attached to the vertical beam 204 so that the support arm 102 with the sensor 29 is adjacent to the vertical beam 204, the antenna arm 104 is positioned in an area of the hinge channel of the container 10, and the data unit 100 is positioned inside the C-channel 206 of the container 10. The antenna arm 104 protrudes from the support arm 102 to an area substantially near the hinge portion of the container 10 in order to remain on the exterior of the container 10 when the door 202 is closed.

In some embodiments, placing the data unit 100 on the interior of the container 10 can reduce opportunities for tampering and/or damage to the CSD 12. For example, because the data unit 100 is disposed in the C-channel 206, even though the contents of the container 10 can shift during transport, the contents are not likely to strike or damage the CSD 12.

Although the above embodiment is shown as a single unit comprising at least one sensor and an antenna 20 for communicating with the reader 16, the CSD 12 can be implemented as several units. For example, a light, temperature, or radioactivity sensor can be positioned anywhere inside the container 10. The sensor can take readings and transmit the readings via a short range communication system (e.g., Bluetooth), to an antenna unit that relays the readings or other information to the reader 16. The sensors can be remote and separate from the antenna unit. In addition, the above embodiment illustrates a CSD 12 that comprises a door sensor 29 for determining whether a security breach has occurred. However, an unlimited variety of sensors can be employed to determine a security breach in place of, or in addition to, the door sensor 29. For example, a light sensor can sense fluctuations in light inside the container 10. If the light exceeds or falls below a predetermined threshold, then it can be determined that a security breach has occurred. A temperature sensor, a radioactivity sensor, a combustible gas sensor, or another sensor can be used in a similar fashion.

In one embodiment, the CSD 12 can trigger the physical locking of the container 10. For instance, a reader 16 can be configured, via a "security request," to secure the contents of the container 10. When this happens, the PCBA 220 can initiate locking of the container 10 by energizing elecromagnetic door locks or another locking mechanism. Once the container is secured via the security request, the container 10 is physically locked to deter theft or tampering.

Exemplary Embodiment of a Reader

As shown in Fig. 3 A, one embodiment of the reader 16 comprises a short range communication unit 30, a microprocessor 36, a memory 38, and a power supply 40. The short range communication unit 30 can achieve the wireless short-range, low-power communication link to the CSD 12 as described above with reference to Fig. 2A. The reader 16 can further comprise, or separately attach to, a device that achieves a link to a remote container-surveillance system (e.g., according to GSM, CDMA, PDC, or DAMPS wireless communication standards or using a wired LAN or a wireless local area network WLAN, Mobitex, GPRS, UMTS). Those skilled in the art will understand that other communications standards can be used. Examples include satellite data communication standards like Inmarsat, Iridium, Project 21, Odyssey, Globalstar, ECCO, Ellipso, Tritium, Teledesic, Spaceway, Orbcom, Obsidian, ACeS, Thuraya, or Aries in cases where terrestrial mobile communication systems are not available.

The reader 16 can further comprise, or attach to, a satellite positioning unit 34 for identifying the location of a vehicle on which the container 10 is loaded. For example, the reader 16 can be the mobile reader 16(B) attached to a truck, ship, or railway car. Positioning unit 34 can be omitted, for example, in embodiments where tracking and positioning of the container 10 is not necessary (e.g., if the location of the fixed reader 16(C) is known). In some embodiments, positioning unit 34 is configured to use satellite positioning systems such as GPS, GNSS, or GLONASS. In other embodiments, the reader 16 can determine its position using a purely mobile communication network (e.g., EOTD), or using a combination of satellite and mobile communication network based positioning techniques (e.g., Assisted GPS).

The microprocessor 36 and the memory 38 in the reader 16 can allow for: control of data exchanges between the reader 16 and the CSD 12; a remote surveillance system as explained above; and for a storage of such exchanged data. Power for the operation of the components of the reader 16 can be provided through a power supply 40.

Fig. 3B is a diagram of one embodiment of a handheld reader 16(A). The handheld reader 16(A) can communicate with the CSD 12 via, for example, a short- range direct sequence spread spectrum radio interface. In one embodiment, when the handheld reader 16(A) and the CSD 12 are within close range of one another (e.g., <100 m), the CSD 12 and the handheld reader 16(A) can communicate with one another. In some embodiments, the handheld reader 16(A) can be used to electronically secure or disarm the container via communication with the CSD 12. The handheld reader 16(A) can also be used to obtain additional information from the CSD 12 such as, for example, information from other sensors inside the container 10 or readings from the door sensor 29.

The embodiment of the handheld reader 16(A) shown in Fig. 3B is adapted to be interfaced with and attached to a mobile phone, PDA or similar device 16(Al). In other embodiments, the handheld reader 16(A) can be a standalone unit or can be adapted to be interfaced with, for example, a PDA or a handheld or laptop computer. The reader 16 can be configured to draw power from the attached device and utilize Bluetooth, or any similar interface, to communicate with the attached device.

Exemplary Application Scenarios

Additional application scenarios for the application of the CSD 12 and reader 16 are shown in Figs. 4-8. In these and other embodiments, reader 16(B) can be attached or detached to different transporting or transported units by an appropriate means.

Fig. 4 shows a first possible application scenario of the CSD 12 and the reader 16. As shown in Fig. 4, in one embodiment related to road transportation, the reader 16 is coupled to the gate or a shipping warehouse or anywhere along the supply chain. In such a case, the reader 16 can easily communicate with the CSD 12 of the container 10 via the antenna 20 when the container is being towed by the truck when exiting a shipping area. Another option is to provide the reader 16 as a handheld reader 16(A) as described above and then either scan the CSD 12 as the truck leaves the area, or carry the hand-held reader 16(A) within the cabin of the truck during surveillance of the container 10.

Fig. 5 shows a second possible application scenario for the CSD 12 and the reader 16 as related to rail transportation. In particular, Fig. 5 shows the reader 16 positioned near a rail line for wireless communication to those containers located in the reach of the reader 16. The reader 16 can then communicate with any or all of the devices 12 of the containers 10 that are transported on the rail line.

Fig. 6 involves containers 10 aboard a ship 601. Here, for a container to be identified, tracked, or monitored during sea transport, a reader 16 is placed in range of the CSD 12 attached to the container 10. In one embodiment, readers 16 are distributed over the ship, perhaps according to a loading scheme for the containers 10. The readers 16 can be detachably mounted on the ship 601 such that, once container surveillance is no longer desired, the reader 16 can be moved to a different area of the ship 601 or a different transporting device. In some embodiments, the reader 16 can communicate with AIS, based on VHF communication, or with Inmarsat satellites. The technology can also be used within a restricted area, such as a shipping yard 700, as shown in Fig. 7. In one embodiment, readers 16 can be placed on equipment that is near to or is handling the containers 10, such as a crane 710 or a straddle carrier 720. Other possible locations for readers 16 are: in-gates and out-gates, top-loaders, side-loaders, reach stackers, transtainers and hustlers. In one embodiment, a specific container 10 can be located using a plurality of readers 16 spread over the shipping yard 700.

Exemplary Securing Processes

Fig. 8 illustrates a diagram of one embodiment of a securing process, with steps of the process represented in part by arrows. At step 800, reader 16 requests identification from the CSD 12. At step 802, the CSD 12 transmits the identification to the reader 16 and, at step 804, the reader 16 selects a container 10 to secure. A request is sent from the reader 16 to the server 15 at step 806. At step 808, the server 15 generates a security key and encrypts the security key with an encryption code. At step 810, the encrypted security key is transmitted to the CSD 12 via the reader 16 in order to secure the container 10. At step 812, the security key is decrypted and stored in the CSD 12. A similar procedure can be initiated to disarm the container 10. The container 10 can be secured automatically when passing in range of a reader 16, or a user can secure or disarm specific chosen containers 10.

Fig. 9 illustrates a diagram of one embodiment of a status check process. At step 900, the reader 16 transmits a challenge to the container 10 in question. At step 902, the CSD 12 of the container 10 generates a response using a security key and an encryption code. At step 904, the response is sent from the CSD 12 to the reader 16. At step 906, the reader 16 also sends a challenge to the server 15. The challenges to the server 15 and the CSD 12 can be transmitted substantially simultaneously or at alternate points in time. The server 15 generates and sends a response utilizing the security key and an encryption code to the reader 16 at steps 908 and 910 respectively. At step 912, the reader 16 determines if the responses are equal. If the responses are equal, then the container 10 remains safely secured. Alternatively, if the responses are not equal, then a security breach of the container 10 has occurred. Similarly to the securing and disarming processes, a status check can be performed automatically as the container 10 passes in range of a reader 16, or a user can initiate a status check during transport.

Fig. 10 shows a flowchart of one embodiment of a method 1000 for using the CSD 12 to monitor a container 10. When the container door is closed (step 1010) and the CSD 12 is armed (step 1020), the CSD 12 determines which of one or more possible alarm limits to apply (step 1030). In some embodiments, alarm limits are measurement variances which, when exceeded, can indicate that a possible security breach has occurred. For example, returning to Fig. 2K, in one embodiment the alarm limit can be defined as a maximum variance in the distance (referred to herein as the "door distance") between the container's vertical beam 204 and the container door 202 (as measured by the CSD 12) at the time the CSD 12 is armed. In other embodiments, the CSD 12 measures a distance between the door 202 and a feature of the container 10 besides the vertical beam 204. In still other embodiments, an alarm limit can be a maximum variance in an absolute, preset distance. In some embodiments, the alarm limit is on the order of several millimeters, e.g., about ± 4 mm. When the CSD 12 measures a door distance outside of the alarm limits, the CSD 12 can interpret this as a sign of a security breach, e.g., an indication that the container door 202 has been opened. Another exemplary scenario that can result in the CSD 12 measuring a door distance outside of the alarm limits is when the door 202 is detected as being too close to the vertical beam 204. Such a measurement can result if, for example, a piece of sheet metal is placed between the door 202 and the sensor 29. Possible methods for determining the alarm limits to apply are explained below, and in some embodiments alarm limits can be determined repeatedly over a period of time (e.g., multiple times per second). Alarm limits can be applied in step 1040, e.g., they can be compared with readings from sensor 29. In one embodiment, when the comparison indicates that one or more readings from sensor 29 exceed the determined alarm limits, a tamper alarm condition is set (step 1050) which can cause an audible or visual alarm to be emitted or data to be recorded by the CSD 12. In another embodiment, one sensor reading exceeding the determined alarm limits is sufficient to trigger a tamper alarm condition, while in yet another embodiment several consecutive or non-consecutive sensor readings over a period of time can trigger a tamper alarm condition.

Because of design and manufacturing tolerances on containers, it is not unusual for the door on a container 10 to move relative to other parts of the container (e.g., the door can rock back and forth) during transport, even when the door is closed. For example, on at least some containers the door 202 (in a closed position) does not maintain a constant distance from the container's vertical beam 204, due to movements during container transport. This distance, which for some containers is about 12 mm to about 20 mm, can change by a distance on the order of several millimeters or more. Accordingly, the distance measured by the door sensor 29 of the CSD 12 can change as the container 10 moves and the door 202, although remaining closed, moves relative to the vertical beam 204. One approach to dealing with this aspect of the moving door is to set the alarm limits large enough to accommodate the shifting of the door (referred to herein as "worst-case limits") and to use worst-case alarm limits whenever the CSD 12 is armed. However, using worst-case alarm limits can allow for circumvention measures. For example, a CSD 12 applying worst-case alarm limits can not necessarily distinguish between a door distance that has changed due to motion of the container 10 and a door distance that has decreased due to a piece of sheet metal positioned between the CSD 12 and the door 202 (e.g., a piece of sheet metal placed there to circumvent the CSD 12). In another embodiment, two sets of alarm limits are available to the CSD 12: a first set for use when the container 10 is moving (referred to herein as "moving alarm limits"), and a second set for use when the container 10 is stationary (referred to herein as "stationary alarm limits"). Generally, "stationary alarm limits" allow for a smaller degree of variation in the door distance than "moving alarm limits." For example, in some embodiments the moving alarm limit can be about 4 mm, while the stationary alarm limit can be about 25-50% of the moving alarm limit, e.g., about 1-2 mm. The CSD 12 can determine which set of alarm limits to use based on input from the accelerometer 225.

Fig. 11 shows a flow diagram of one embodiment of a method for determining which alarm limits to use (i.e., step 1030 of method 1000) based on input from the accelerometer 225. At 1110, measurements are obtained from the accelerometer 225. In some embodiments the method comprises filtering the accelerometer readings (step 1 120), first with a fast hardware LPF, and then with a slow software LPF over a period of time. This can produce an average "window" or range of acceleration readings. At 1 130, the CSD 12 can use the accelerometer readings to classify the condition of the container 10 as "moving" or "stationary." (Note that in some embodiments, "moving" and "stationary" can be approximate terms.) Readings for the window can be taken before the CSD 12 is armed, after it is armed, or during both periods. If the accelerometer readings are within (or, in some embodiments, approximately within) the acceleration window, the container 10 is considered to be stationary. If the accelerometer readings are outside the window, the container 10 is considered to be moving. In other embodiments, the container 10 is classified as "moving" or "stationary" based on a set of absolute parameters. These parameters can be user- selectable. In either case, based on this determination "moving alarm limits" are selected if the container 10 is "moving," and "stationary alarm limits" are selected if the container 10 is "stationary" (step 1140).

In some embodiments, the process of step 1030 can take place periodically, at predetermined or random intervals, or it can take place continuously. In another embodiment, the process of step 1030 begins when CSD 12 determines that the door 202 is positioned outside of a lower alarm limit (e.g., a lesser of two or more alarm limits), at which point the CSD 12 can activate the accelerometer 225 (step 1150). Readings from the accelerometer 225 can be filtered in a LPF in hardware. The LPF can be a slow LPF, e.g., slower than the fast hardware LPF used to determine the window of acceleration readings, as described above. This embodiment can be desirable for reducing power consumption by the CSD 12.

By choosing alarm limits from multiple available alarm limits, the CSD 12 can adapt to situations where a door distance varies due to movement of the container 10, yet apply more stringent alarm limits when the container 10 is stationary. Exemplary Software and Hardware Implementations

The methods described herein can be implemented as computer-executable instructions stored on one or more computer-readable storage media such as floppy disks, RAM, ROM, flash RAM, hard disk drives, or other media as are known in the art. The methods can also be implemented in hardware configurations using components known in the art.

In view of the many possible embodiments to which the disclosed principles can be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting in scope. Rather, the scope of protection is defined by the following claims.

Claims

I claim:

1. A container monitoring device for monitoring a container comprising a door, the device comprising: a sensor for detecting a position of the door and providing sensor readings; an accelerometer for providing accelerometer readings related to movement of the container; and a processor configured to: select one or more alarm limits from a set of alarm limits based at least in part on the accelerometer readings, and evaluate the position of the door according to the sensor readings and according to the one or more selected alarm limits.

2. The container monitoring device of claim 1 , wherein the set of alarm limits comprises a set of stationary alarm limits and a set of moving alarm limits.

3. The container monitoring device of claim 2, wherein the processor is configured to select the set of stationary alarm limits based on a first set of accelerometer readings and to select the set of moving alarm limits based on a second set of accelerometer readings.

4. The container monitoring device of claim 1 , wherein the processor is further configured to indicate an alarm condition according to the evaluation.

5. The container monitoring device of claim 1 , further comprising one or more filters configured to filter the accelerometer readings.

6. The container monitoring device of claim 1 , wherein the processor is further configured to calculate an average accelerometer reading.

7. The container monitoring device of claim 1 , wherein the accelerometer is a 3-axis accelerometer.

8. The container monitoring device of claim 1, wherein the sensor is configured to detect a distance between the door of the container and a doorframe of the container.

9. The container monitoring device of claim 1, wherein the container is a shipping container, and wherein the accelerometer is positioned to measure the motion of the shipping container.

10. The container monitoring device of claim 1 , wherein the processor is further configured to activate the accelerometer based at least in part on the position of the door.

11. A method of monitoring a container, the container comprising a door, the method comprising: obtaining door sensor readings; obtaining accelerometer readings; selecting one or more alarm limits from a set of alarm limits according to the accelerometer readings; and evaluating the door sensor readings according to the selected alarm limits.

12. The method of claim 11, wherein the door sensor readings comprise an approximate distance between the door and a container door frame.

13. The method of claim 11, further comprising indicating an alarm condition as a result of the evaluation.

14. The method of claim 11, further comprising filtering the accelerometer readings.

15. The method of claim 11 , wherein the accelerometer readings are obtained as a result of obtaining the door sensor readings.

16. A computer-readable medium containing instructions which can cause a computer to perform a method comprising: obtaining door sensor readings for a door of a shipping container; obtaining accelerometer readings for the shipping container; and selecting one or more alarm limits from a set of alarm limits according to the accelerometer readings.

17. The method of claim 16, further comprising evaluating the door sensor readings according to the selected alarm limits.

18. The method of claim 17, further comprising indicating an alarm condition as a result of the evaluation.

19. The method of claim 16, wherein the set of alarm limits comprises moving alarm limits and stationary alarm limits.

20. The method of claim 16, wherein the door sensor readings correspond to a distance between the door of the container and a doorframe of the container.