Field of the invention

This invention relates to a tamper detection device, in particular such a device as used with transport containers, and a method of tamper detection.

Background to the invention

Theft of cargo during transport is a major problem worldwide, with goods being removed from cargo containers during transport, containers being intercepted and stolen and also loose materials, such as ore, being removed from trucks and the like during transport.

Small tracking devices to reveal the location of individual objects are known but these do not allow detection of tampering with cargo, such as when a container is opened and the contents replaced.

Summary of the invention

In accordance with one aspect of the present invention, there is provided a tamper detection device for attachment to a magnetisable container, such as a cargo container or a truck, the device comprising at least one magnetic element, a sensor element to detect changes in induced magnetic field between the at least one magnetic element and a magnetisable container to which the device is attachable, and a transmitter element to transmit information or data relating to changes in the induced magnetic field. The device can be attached to an external surface of the container which ensures the contents of the container are not disturbed.

The magnetic element preferably has a permanent magnetic field and is typically a permanent magnet. As the device is to be attached to a magnetisable container, the magnet should be made of a suitable magnetic material that can support a strong magnetic field to allow firm fixing to such a container. Neodymium is particularly suitable for the magnetic material. The device may comprise two spaced apart magnetic elements with the sensor element disposed substantially equidistant between the respective magnetic elements.

Preferably the magnetic elements are arranged in opposing polarity such that lines of magnetic field pass from one magnetic element to the other magnetic element.

The sensor element is preferably substantially planar and the magnetic elements are preferably substantially planar, with the sensor element orientated substantially perpendicular to the orientation of the magnetic elements.

The sensor element and transmitter element may be provided by a microcontroller device such as may be formed on a printed circuit board.

The device may further comprise a tilt sensor element which may be provided as part of a microcontroller device. The tilt sensor is particularly of use when sensing tampering in relation to a tipping truck used to convey raw materials.

The device may further comprise a housing within which the at least one magnetic element, sensor element and transmitter element are located.

The housing is preferably electrically conductive, typically made from metal, so as to shield the sensor element from stray magnetic fields.

The housing may comprise an electrically conductive sleeve, the sensor element being contained within the sleeve and the magnetic element(s) being located external of the sleeve.

Preferably the at least one magnetic element is positioned in the housing so as to be spaced apart from the surface of a magnetisable container when the device is in use. Typically the at least one magnetic element will be spaced around 10mm from the magnetisable container. The transmitter element is preferably configured to communicate with a wireless network. Any suitable network may be used such as for example but not limited to LoRaWAN, LORA. Solar panels may be affixed to an external surface of the housing and arranged to provide electrical power to elements within the housing such as the batteries to enable recharging over prolonged periods of time. The housing may be formed with inclined surfaces on which the solar panels are located. Such inclined solar panels improve the efficiency of collection of solar energy.

In accordance with another aspect of the invention, there is also provided a method for detecting tampering with a magnetisable container, the method comprising positioning at least one magnetic element onto a magnetisable container, detecting changes in the magnetic field induced between the at least one magnetic element and the magnetisable container using a sensor element, transmitting information, such as data, relating to changes in the induced magnetic field. The method ensures a container can be tracked and the location and time of any tampering detected.

The method preferably further comprises acquiring over time information about at least location of the sensor element and magnetic field.

The method may further comprise detecting changes in orientation using a tilt sensor element. Preferably the method may further comprise calibrating the sensor element when the at least one magnetic element is first placed onto the magnetisable container.

The method may further comprise transmitting information using a wireless network, such as for example but not limited to LoRaWAN, LORA.

The method may further comprise storing and recording information in a storage means such as a memory associated with a microcontroller device. This allows the data to be recorded ready for transfer when wireless transmission is possible. Preferably the method further comprises checking for the availability of a wireless datalink and initiating transmission of information such as data once such a datalink is detected.

The invention will now be described, by way of example, with reference to the accompanying drawings in which:

Figure 1 shows a diagram of a first embodiment of a tamper detection device;

Figure 2 shows a schematic diagram of a microprocessor used in the device;

Figure 3 shows a perspective view from the front of a housing forming part of the tamper protection device;

Figure 4 shows a perspective view from the rear of the housing;

Figure 5 shows a diagram illustrating the magnetic field associated with the device; Figure 6 shows an exemplary diagram illustrating induced magnetic field when the device is in use;

Figure 7 shows a diagram of the device in use to secure a container;

Figure 8 shows a graph illustrating information received from the device over time; Figure 9 shows a diagram of a second embodiment of the device;

Figure 10 shows a plan view of the second embodiment with lid removed; and Figure 11 shows an exemplary flow diagram of a method of using the device.

Description

Figure 1 shows a first embodiment of a tamper detection device 10, device 10 comprising permanent magnets 12, 12’ made from Neodymium, a sensor element provided on microprocessor 14, and batteries 16 to power microprocessor 14. Housing 20 encases these elements of the device and comprises metal sleeve 22 and two metal end caps 24 that fit over the open ends of sleeve 22. Microprocessor 14 and batteries 16 are located within sleeve 22, with magnets 12, 12’ disposed in caps 24 so as to be located at opposing ends of sleeve 22. Microprocessor 14 is positioned substantially equidistant between magnets 12, 12’ and orientated substantially perpendicular to magnets 12, 12’. By encasing microprocessor 14 in a metal sleeve it is difficult to distort sensor readings from outside the device. Solar panels 28, see Figure 3, sit on an external surface of housing 20 so as to receive solar radiation and are in electrical communication with electrically powered elements, such as microprocessor 14, within sleeve 22 so as to provide electrical power to recharge batteries 16 and ensure device 10 is operational for long periods, typically several years.

A schematic diagram of microprocessor 14 is shown in Figure 2. Microprocessor 14 is typically formed on a printed circuit board and comprises components such as a magnetometer 30 to detect magnetic field, antenna 32 to transmit, and if required receive, signals to an external monitoring station, microcontroller 34 to control and operate the various components, GPS circuits 36 to determine location, accelerometer 38 and if required tilt sensor 40. A temperature sensor can also be provided.

Alternative housing shapes can be used, see for example Figures 3 and 4 where housing 20’ is formed with an inclined surface 41 on which solar panels 28 are locatable, see Figure 7. By locating solar panels 28 on an inclined surface 41, there is improved collection of solar energy.

Figure 5 illustrates the magnetic field associated with device 10 before placement externally on a magnetisable container, such as a transport container or truck body. Magnetic field lines 42 run from magnet 12’ to magnet 12, magnets 12, 12’ arranged in opposing polarity so that lines of magnetic field pass from one magnet to the other.

When device 10 is placed externally on a magnetisable container 50, see Figures 6 and 7, magnets 12, 12’ securely fix device 10 to container 50. A magnetic field is induced in container 50 by the magnets and a modified induced magnetic field 52 created as shown by the magnetic field lines with the induced magnetic field acting as a magnetic fingerprint for that combination of device and container. The strength of the induced magnetic field is sensed by magnetometer 30. Device 10 is typically secured across a door opening, see Figure 7, so that device 10 needs to be moved to allow opening of the door 54. Movement or removal of device 10 causes a change in the induced magnetic field which is sensed by magnetometer 30 and data relating to this change in magnetic field is transmitted by antenna 32 to an external monitoring station when a wireless network is accessible. Any wireless network is suitable but of preference low cost networks such as LoRa or LoRaWAN.

If desired the device can be permanently incorporated in part of the door, for example within door tab 56.

As can be seen from the graph of Figure 8 where magnetic field is displayed over time, removal of device 10 from door 54 triggers large changes in the induced magnetic field, see spike 60, and it can be determined where and when device 10 was removed using location data from GPS 36. Real-time information can be provided as long as device 10 is within a wireless network area. If device 10 is outside a wireless network area, data is stored within microprocessor 14 until a wireless network becomes available when the information is then transmitted. Typically the transmitted data will include a date stamp and time stamp. The location over time, and so the journey of the device, can be monitored and the place and time where tampering takes place identified.

A second embodiment of a tamper detection device 70 is shown in Figures 9 and 10 where magnets 20, 20’ are within a rectangular shaped housing 72, with microprocessor 14 disposed between the magnets. Batteries 16 to power microprocessor 14 are disposed above microprocessor 14 and magnets 20, 20’. If desired solar cells 74 can be positioned within lid 78 to provide additional electrical power for recharging batteries 16. The device is waterproof and robust with a rubber inner liner 76 to protect the contents and act as an o-ring seal when lid 78 is closed. This particular embodiment incorporates a tilt sensor and is particularly suitable for use on tipper trucks where one wishes to know whether any of the load has been offloaded before final delivery at an authorised destination. As with the first embodiment, movement of device 70 whether by removal or by alteration of the angle relative to the Earth’s magnetic field generates a change in the induced magnetic field which is detected and reported back to a monitoring station, with a graph similar to that shown in Figure 8 obtained over time. The flow diagram of Figure 11 shows an example of typical method steps involved in monitoring for tampering using devices 10 and 70. Initially the device is placed on a magnetisable container, step 100, and activated. After a short delay calibration takes place at step 102 so as to determine the initial induced magnetic field and the location and orientation of device 10, 70. The microprocessor 14 then reports at predetermined intervals on the position, orientation, and at step 103 the induced magnetic field, checking for a data downlink and transmitting accumulated data at step 104 if a network connection is identified. If no network connection is identified at step 105 then data is stored in a memory buffer and transmitted when a connection becomes available. If the stored data exceeds the amount of memory space available, then newer data will replace the old data, see step 106.

As the device monitors induced magnetic field when placed on a magnetisable container, changes in induced magnetic field can be used to provide an alert when a conveyed load is being tampered with. Being able to attach the device to the outside of a container or lorry ensures the device does not interfere with the load and complications with shipments are avoided as no custom seals need to be broken to use the device.