A monitoring device

Abstract

A monitoring device 100 and method for monitoring marine cargo 12, where data corresponding to rigid body motions of cargo on a ship (10, fig 1) are measured or received, a control module 104 determines the maximum motions of the cargo during a monitoring period and compares them to a motion threshold, where alert data is generated when the threshold is exceeded, and a satellite communication module 108 transmits the alarm data to a remote device 102. Thereby, a remote user can monitor the safety to the cargo and be alerted to potential damage. Also claimed is a further monitoring device where a sensor 106 determines position data corresponding to a position of the device, where that data is communicated via satellite. The devices may comprise a water-proof housing with the sensor, the satellite communication module and the control module wholly housed within. The motion sensed may be pitch, roll or yaw of the cargo, or acceleration such as surge, sway or heave.

Description

FIELD The present teachings relate to a monitoring device for monitoring marine cargo, and a method for monitoring marine cargo. BACKGROUND Marine cargo (i.e. cargo transported via watercraft such as ships) is typically subjected to significant rigid body motions (e.g. pitch, roll, heave etc.) during transportation, especially when travelling in rough sea conditions (e.g. during a storm). Depending on the cargo, such motions have the potential to damage the cargo. The motions of some marine cargo, particularly high value cargo such as project cargo (e.g. wind turbine components), must comply with agreed motion criteria during transportation to help prevent damage occurring to the cargo, for the purpose of being insurable. Devices are known that are designed to be mounted to marine cargo which, when inspected, indicate whether such motion criteria has been complied with. However, a problem with such devices is that a stakeholder (e.g. an owner or insurer of the cargo) must wait until after the marine cargo has been transported to determine whether the motion criteria have been complied with. As such, the stakeholder is unable to take any mitigative or preventative measures to prevent damage occurring to the cargo during transportation. The present teachings seek to overcome or at least mitigate one or more problems associated with the prior art. SUMMARY According to a first aspect of the present teachings, there is provided a monitoring device for monitoring marine cargo, comprising: a sensor arrangement configured to determine motion data corresponding to one or more rigid body motions of the cargo; a satellite communication module for communicating with a remote device via satellite communication; and a control module configured to: receive motion data determined by the sensor arrangement over a predetermined monitoring period; determine one or more maximum motions of the cargo during the monitoring period based on the received motion data; and generate alert data when at least one determined maximum motion exceeds a corresponding first predetermined motion threshold. The satellite communication module is configured to transmit the generated alert data to said remote device. Advantageously, the monitoring device may inform a remote user during transportation that the cargo has been subjected to motion which has the potential to damage the cargo. This enables the remote user to inform an operator of a watercraft transporting the cargo so that they can take mitigative action if necessary. Moreover, processing motion data determined during monitoring periods periodically helps to reduce the frequency of transmissions by the satellite communication module and the amount of data that needs to be transmitted. The alert data may comprise data based on the received motion data. Advantageously, such alert data may enable a remote user to determine the risk of damage to the cargo, and whether mitigative action is needed. The alert data may comprise data corresponding to the one or more determined maximum motions of the cargo. Advantageously, transmitting the determined maximum motion(s) of the cargo to the remote device may indicate the likelihood of damage to the cargo. The control module may be configured to generate warning data when at least one determined maximum motion exceeds a corresponding second predetermined motion threshold less than the corresponding first predetermined motion threshold. The satellite communication module may be configured to transmit the generated warning data to the remote device. The monitoring device may comprise a short-range wireless communication module configured to transmit the generated warning data to a watercraft transporting the cargo via wireless communication. Such a configuration of the control module may warn a stakeholder and / or an operator of the watercraft that motion criteria are close to being exceeded so that mitigative and / or preventative action may be taken. The determined one or more maximum motions may comprise one or more maximum rotation motions (e.g. in pitch, roll or yaw) of the cargo during the monitoring period. Such a configuration may enable a remote user to monitor for excessive rotation of the cargo, which could cause the cargo to shift and become damaged. The one or more maximum rotation motions may comprise at least one maximum rotation angle amplitude, and / or at least one maximum rotation cycle frequency. The determined one or more maximum motions may comprise one or more maximum linear accelerations (e.g. in surge, sway or heave) of the cargo during the monitoring period. Such a configuration may enable a remote user to monitor for excessive acceleration of the cargo, which has the potential to damage the cargo directly, or indirectly (e.g. excessive acceleration of the cargo may cause the cargo to detach from a watercraft transporting the cargo). The determined one or more maximum motions may comprise at least one maximum pitch rotation motion, at least one maximum roll rotation motion, and at least one maximum heave acceleration, of the cargo during the monitoring period. The determined one or more maximum motions may further comprise at least one maximum heave displacement of the cargo during the monitoring period. The control module may be further configured to: determine one or more time-averaged motions of the cargo during the monitoring period based on the received motion data; and generate alert data when at least one determined time-averaged motion exceeds a corresponding predetermined threshold. Advantageously, such a configuration may enable a remote user to be informed of potential listing of a watercraft transporting the cargo, so that they may inform an operator of the watercraft, who can take mitigative action if required. The one or more time-averaged motions of the cargo may comprise a time-averaged roll angle amplitude of the cargo. The corresponding predetermined threshold may be 5 degrees or more. The monitoring period may be at least 60 seconds. Advantageously, such monitoring periods help to reduce the frequency of transmissions by the satellite communication module and the amount of data that needs to be transmitted. The monitoring period may be in the range of 60 to 3600 seconds. The monitoring period may be in the range of 60 to 1800 seconds. The monitoring period may be in the range of 60 to 600 seconds. The monitoring device may further comprise a memory module. The control module may be configured to store record data determined by the control module in the memory module, receive a request for record data from a remote device via the satellite communication module, and retrieve record data from the memory module in response. The satellite communication module may be configured to transmit data based on the retrieved record data to said remote device. Such a configuration enables a remote user to obtain more detailed information regarding the device and / or cargo than they would obtain from alert data or status data transmitted by the device. For example, a remote user may obtain detailed cargo motion information at the time of a specific event, such as a collision, occurring. The record data may be based on the received motion data. The sensor arrangement may be configured to determine position data corresponding to a position of the monitoring device. The alert data may comprise data based on the determined position data. Such alert data may enable a remote user to be informed of a location of the cargo at a time when the cargo was subjected to excessive and potentially damaging motion. The monitoring device may further comprise a short-range wireless communication module for communicating with a watercraft transporting the marine cargo via wireless communication. The short-range wireless communication module may be configured to transmit the alert data to said watercraft. Advantageously, this may enable an operator of the watercraft to take action (e.g. reduce the speed of the watercraft) to reduce the motion of the cargo. The control module may be configured to periodically generate status data (e.g. corresponding to one or more of a time, a position of the device, a power status of the device, and a temperature of the device). The satellite communication module may be configured to transmit the status data to a remote device. Advantageously, the status data may inform a remote user of the health of the device. The monitoring device may further comprise a power supply arrangement configured to independently supply power to the device. Such a power supply arrangement helps to increase the flexibility for where the device can be located since an external power supply is not required. Moreover, such a power supply arrangement helps to reduce the dependency of the cargo's stakeholders on the owners / operators of a watercraft transporting the cargo. The power supply arrangement may comprise a power storage module (e.g. one or more batteries). The power supply arrangement may comprise a power generation module (e.g. a solar panel). The power generation module may help to extend the operation life of the device. The monitoring device may further comprise a (e.g. waterproof or water resistant) housing. The sensor arrangement, the control module, and the satellite communication module may be at least partially housed within the housing. Advantageously, the housing helps to protect the components from the external environment. The housing may comprise a mounting arrangement for mounting the housing to a watercraft or the cargo. The determined one or more maximum motions may comprise a maximum roll angle amplitude of the cargo during the monitoring period. The corresponding motion threshold may be in the range of 15 to 35 degrees; optionally, 20 to 30 degrees. The determined one or more maximum motions may comprise a maximum pitch angle amplitude of the cargo during the monitoring period. The corresponding motion threshold may be in the range of 2.5 to 35 degrees; optionally, 10 to 30 degrees. The determined one or more maximum motions may comprises a maximum roll and / or pitch cycle frequency of the cargo during the monitoring period. The corresponding motion threshold may be in the range of 0 to 0.2 hertz; optionally, approximately 0.1 hertz. The determined one or more maximum motions may comprise a maximum heave acceleration of the cargo during the monitoring period. The corresponding motion threshold may be in the range of 0 to 0.5 g; optionally, 0.1 to 0.3 g, for example, approximately 0.2 g. According to a second aspect of the present teachings, there is provided a monitoring device for monitoring marine cargo, comprising: a sensor arrangement configured to determine motion data corresponding to one or more rigid body motions of the cargo; a satellite communication module for communicating with a remote device via satellite communication; and a control module configured to: receive motion data determined by the sensor arrangement over a predetermined monitoring period; determine one or more time-averaged motions of the cargo during the monitoring period based on the received motion data; and generate alert data when at least one determined time-averaged motion exceeds a corresponding first predetermined threshold. The satellite communication module is configured to transmit the generated alert data to said remote device. The one or more time-averaged motions of the cargo may comprise a time-averaged roll angle amplitude of the cargo. The corresponding predetermined threshold may be 5 degrees or more. The control module may be configured to generate warning data when at least one determined time-averaged motion exceeds a corresponding second predetermined threshold less than the corresponding first predetermined threshold. The satellite communication module may be configured to transmit the generated warning data to the remote device. The monitoring device may comprise a short-range wireless communication module configured to transmit the generated warning data to a watercraft transporting the cargo via wireless communication. The monitoring device according to the second aspect may include any of the features described above in relation to the first aspect. According to a third aspect of the present teachings, there is provided a monitoring device for monitoring marine cargo, comprising: a sensor arrangement configured to determine motion data corresponding to one or more rigid body motions of the cargo, and / or position data corresponding to a position of the device; a satellite communication module for communicating with a remote device via satellite communication; a control module; and a housing, such as a waterproof or water-resistant housing. The satellite communication module comprises an antenna. The control module is configured to generate data based on the data determined by the sensor arrangement. The satellite communication module is configured to transmit the generated data to said remote device via the antenna. The sensor arrangement, the satellite communication module and the control module are wholly housed within the housing. Advantageously, the housing helps to protect the components from the external environment. The monitoring device may further comprise a power supply arrangement configured to independently supply power to the device. The power supply arrangement may be at least partially housed within the housing. The power supply arrangement may comprise a solar panel mounted to an exterior surface of the housing. The monitoring device according to the third aspect may include any of the features described above in relation to the first and second aspects. According to a fourth aspect of the present teachings, there is provided an assembly comprising the monitoring device according to the first, second or third aspects mounted to an item of cargo (e.g. containerised or project cargo) or a watercraft. According to a fifth aspect of the present teachings, there is provided a method for monitoring marine cargo, comprising: receiving motion data corresponding to one or more rigid body motions of the cargo determined over a monitoring period; determining one or more maximum motions of the cargo during the monitoring period based on the received motion data; generating alert data when at least one determined maximum motion exceeds a corresponding predetermined motion threshold; and transmitting the alert data to a remote device via satellite communication. The method according to the fifth aspect may include any of the features described above in relation to first, second, third and fourth aspects. According to a sixth aspect of the present teachings, there is provided a method for monitoring marine cargo, comprising: receiving motion data corresponding to one or more rigid body motions of the cargo determined over a monitoring period; determining one or more time-averaged motions of the cargo during the monitoring period based on the received motion data; generating alert data when at least one determined time-averaged motion exceeds a corresponding predetermined threshold; and transmitting the alert data to a remote device via satellite communication. The method according to the sixth aspect may share any of the features described above in relation to first, second, third and fourth aspects. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments are now disclosed by way of example only with reference to the drawings, in which: Figure la is a side view of a watercraft with marine cargo and a monitoring device onboard according to an embodiment; Figure lb is a plan view of the watercraft of Figure la; Figure 2 is a block diagram representation of an embodiment of the monitoring device of Figure la; Figure 3 is an isometric view of an embodiment of the monitoring device of Figure la; Figure 4 is a flowchart representation of an exemplary process performed by an embodiment of the monitoring device of Figure la; and Figure 5 is a flowchart representation of an exemplary process performed by an embodiment of the monitoring device of Figure la. DETAILED DESCRIPTION OF EMBODIMENT(S) Figures la and lb show marine cargo 12 onboard a watercraft 10. The watercraft 10 is configured to transport the marine cargo 12 through a body of water 14, such as an ocean, sea or river, and includes a bridge or wheelhouse 10a. In the illustrated embodiment, the watercraft 10 is a cargo ship suitable for transporting the marine cargo 12. The marine cargo 12 is project cargo, such as a structure of a wind turbine (e.g. a wind turbine tower or blade) or a (e.g. oil or gas) pipe, for example. In alternative embodiments (not shown), the cargo may be any suitable marine cargo (e.g. containerised cargo, or bulk cargo), and the watercraft 10 may be any suitable watercraft (e.g. any suitable ship (e.g. a bulk carrier or a container ship), boat, barge or vessel). In alternative embodiments (not shown), the marine cargo 12 may instead be in the water 14 and towed by the watercraft 10. In such embodiments, the marine cargo 12 may need to be modified to ensure that it is buoyant. In response to a variety of different forces acting on the watercraft 10 (e.g. propulsive, wind and wave-induced forces), the watercraft 10 tends to move as a rigid body in all six degrees of freedom (discussed more below) relative to an Earth-fixed frame of reference. The cargo 12 is attached to (e.g. tethered to) the watercraft 10. As such, as the watercraft 10 moves it exerts forces upon the cargo 12, causing the cargo 12 to move as a rigid body in all six degrees of freedom. In the illustrated embodiment, the cargo 12 is substantially fixed relative to the watercraft 10. With reference to the perpendicular axes x, y, z shown in Figures la and lb, the cargo 12 moves in surge (i.e. translates along the x-axis), sway (i.e. translates along the y-axis), heave (i.e. translates along the z-axis), roll (i.e. rotates about the x-axis), pitch (rotates about the y-axis) and yaw (i.e. rotates about the z-axis). The x-axis is parallel to a longitudinal axis of the watercraft 10 extending between its bow and stern. The y-axis is parallel to a transverse axis of the watercraft 10 extending between its port and starboard sides. The z-axis is parallel to a vertical axis of the watercraft 10. It will be understood that movement of the cargo 12 in one or more of its six degrees of freedom (surge, sway, heave, pitch, roll, yaw) may be oscillatory or at least include oscillatory components (i.e. the cargo 12 may experience cycles of motion in one or more of its six degrees of freedom). It is common for the motions of some marine cargo, particularly high value cargo such as project cargo, to be required to comply with predetermined motion criteria during transportation (e.g. for the purposes of being insurable). For example, maximum limits are typically imposed on one or more of the roll angle amplitude, pitch angle amplitude, roll cycle frequency (i.e. the number of roll cycles per unit time), pitch cycle frequency (i.e. the number of pitch cycles per unit time), and heave acceleration, that the cargo can be subjected to. However, maximum limits may additionally or alternatively be imposed on any rigid body motion of the cargo (e.g. surge speed, surge acceleration, surge cycle frequency, sway displacement, sway speed, sway acceleration, sway cycle frequency, heave displacement, heave speed, heave cycle frequency, yaw angle amplitude, yaw cycle frequency, roll / pitch / yaw angular velocity, and / or roll / pitch / yaw angular acceleration). It will be appreciated that the inverse of each motion cycle frequency is a motion cycle period (i.e. the time taken to complete one cycle of motion). As such, a maximum limit on a motion cycle frequency has an equivalent minimum limit on the corresponding motion cycle period. To monitor the motions of the marine cargo 12 for compliance with predetermined motion criteria, a monitoring device 100 is fixed to the marine cargo 12. In alternative embodiments (not shown), the monitoring device 100 may instead be fixed to the watercraft 10 (e.g. to an exposed deck of the watercraft 10). With further reference to Figure 2, the monitoring device 100 is configured to determine motion data corresponding to one or more rigid body motions of the cargo 12, determine one or more maximum motions of the cargo 12 based on the determined motion data, generate alert data when at least one determined maximum motion exceeds a corresponding motion threshold, and transmit the generated alert data to one or more remote devices 102 (e.g. a remote server, computer, and / or portable electronic device) via satellite communication. As such, a stakeholder (e.g. an owner or an insurer of the cargo 12) can be rapidly informed when a motion threshold has been exceeded regardless of where the cargo 12 is located in relation to the remote device(s) 102 (e.g. the remote device(s) 102 may be land-based). This enables the stakeholder to inform an operator of the watercraft 10 that excessive cargo motion has been detected, who may then take suitable preventative and / or mitigative measures in response if necessary (e.g. reducing the speed and / or changing the course of the watercraft 10). The monitoring device 100 includes a control module 104 (e.g. a suitable microcontroller), a sensor arrangement 106, a satellite communication module 108, a power supply arrangement 110, a memory module 112 (e.g. a hard drive, a solid state drive (SSD), and / or a secure digital (SD) card), and a short-range wireless communication module 114. The satellite communication module 108 is configured for communication with the one or more remote devices 102 via satellite communication. The satellite communication module 108 includes a satellite transceiver with an antenna 108a for transmitting radio signals to, and receiving radio signals from, satellites (e.g. via the IridiumRTM satellite constellation). In alternative embodiments, the satellite communication module 108 may be configured to only transmit signals. The sensor arrangement 106 includes a motion sensor arrangement 106a and a position sensor arrangement 106b, both in communication with the control module 104. The position sensor arrangement 106b is configured to determine position data corresponding to a position of the monitoring device 100, and send the determined position data to the control module 104. The position sensor arrangement 106b includes one or more position sensors configured to determine the position data (e.g. a GPS sensor). The position data may include geographic coordinates of the device 100 (i.e. latitude and longitude). The position data may include a time at which a position of the device 100 is determined (e.g. obtained from a GPS satellite). The motion sensor arrangement 106a is configured to determine motion data corresponding to one or more rigid body motions of the cargo 12, and send the determined motion data to the control module 104. For example, the motion data may include data corresponding to a displacement, a speed and / or an acceleration of the cargo 12 for each of the one or more rigid body motions. The motion sensor arrangement 106a includes one or more motion sensors configured to determine the motion data. For example, the motion sensor arrangement 106a may include one or more of: an inclinometer for determining roll and / or pitch angles / angular rates, an accelerometer for determining surge, sway and / or heave accelerations, and / or roll, pitch and / or yaw angles, a gyroscope for determining roll, pitch and / or yaw angular rates, and / or an inertial measurement unit (IMU) for determining roll, pitch and / or yaw angles / angular rates and / or surge, sway and / or heave accelerations. It will be appreciated that linear and angular displacements may be determined from linear speeds and angular rates respectively, which may be determined from linear accelerations and angular accelerations respectively, via integration. In some embodiments, the motion sensor arrangement 106a may include a nine degree of freedom inertial measurement unit, comprising a gyroscope, an accelerometer and a magnetometer, which determines at least roll, pitch and yaw angles, surge, sway and heave accelerations, and heading. Since the monitoring device 100 is fixed to the cargo 12, the monitoring device 100 moves as a rigid body in all six degrees of freedom in a substantially identical manner to the cargo 12. As such, rigid body motions of the monitoring device 100 determined by the motion sensor arrangement 106a are substantially identical to corresponding rigid body motions of the cargo 12. Likewise, in embodiments in which the monitoring device 100 is fixed to the watercraft 10, rigid body motions of the monitoring device 100 determined by the motion sensor arrangement 106a are substantially identical to corresponding rigid body motions of the cargo 12 since the cargo 12 is substantially fixed relative to the watercraft 10. The control module 104 is configured to receive motion data determined by the motion sensor arrangement 106a over a predetermined monitoring period. The control module 104 (at least temporarily) stores the received motion data (e.g. in the memory module 112 discussed more below or in a random access memory (RAM)). The monitoring period may be at least 1 minute (i.e. 60 seconds). In some embodiments, the monitoring period may be in the range of 1 minute to 1 hour (i.e. 60 to 3600 seconds). In such embodiments, the monitoring period may be in the range of 1 minute to 30 minutes (i.e. 60 to 1800 seconds). In such embodiments, the monitoring period may be in the range of 1 minute to 10 minutes (i.e. 60 to 600 seconds). For example, the monitoring period may be approximately 5 minutes (i.e. 300 seconds). In some embodiments, the monitoring period may be fixed. The motion sensor arrangement 106a is configured such that the determined motion data for each monitoring period includes a plurality of data samples corresponding to each monitored rigid body motion of the cargo 12. The motion sensor arrangement 106a may be configured to determine the motion data at a sampling frequency in the range of 1 to 100 hertz; optionally 1 to 50 hertz, for example approximately 10 hertz. The control module 104 is configured to determine one or more maximum motions of the cargo 12 during the monitoring period based on the received motion data. By 'a maximum motion of the cargo 12' it is intended to mean a maximum perturbation to the motion of the cargo 12 (e.g. a maximum perturbation to a displacement, speed or acceleration of the cargo 12), ora maximum motion cycle frequency of the cargo 12, in one of the cargo's six degrees of freedom. The determined one or more maximum motions may include one or more maximum rotation motions (e.g. in pitch, roll or yaw), and / or one or more maximum linear motions (e.g. in surge, sway or heave) during the monitoring period. The one or more maximum rotation motions may include at least one maximum rotation angle amplitude, at least one maximum rotation angular rate, and / or at least one maximum rotation cycle frequency. The one or more maximum linear motions may include at least one maximum linear displacement, at least one maximum linear speed, and / or at least one maximum linear acceleration. In an exemplary embodiment, the motion data determined by the motion sensor arrangement 106a over the monitoring period includes: pitch angle data, roll angle data, and heave acceleration data (e.g. all determined by an IMU). Based on this motion data, the control module 104 determines the following maximum motions of the cargo 12 during the monitoring period: a maximum pitch angle amplitude, a maximum roll angle amplitude, a maximum pitch cycle frequency, a maximum roll cycle frequency, a maximum heave acceleration, and a maximum heave displacement. These maximum motions can be determined from the motion data efficiently via a suitable frequency analysis-based process, such as via Fourier analysis (e.g. via a fast Fourier transform (FFT)) of the motion data, or via a suitable recursive time-domain state estimation process. The maximum heave displacement may be determined from the heave acceleration data (e.g. by assuming simple harmonic motion of the cargo 12 in the heave direction). In alternative embodiments (not shown), the control module 104 may be configured to determine only one or more of the foregoing maximum motions of the cargo 12 during the monitoring period. The control module 104 is configured to compare each determined maximum motion of the cargo 12 during the monitoring period to a corresponding predetermined motion threshold. For example, the predetermined motion threshold(s) may correspond to the predetermined motion criteria previously discussed. In the foregoing exemplary embodiment, the control module 104 compares the determined maximum motions of the cargo 12 during the monitoring period to a respective: pitch angle amplitude threshold, roll angle amplitude threshold, pitch cycle frequency threshold, roll cycle frequency threshold, heave acceleration threshold, and heave displacement threshold. For example, the roll angle amplitude threshold may be 5 degrees or more; optionally, the roll angle amplitude threshold may be in the range of 15 to 35 degrees; optionally, 20 to 30 degrees. The pitch angle amplitude threshold may be in the range of 2.5 to 35 degrees; optionally, 10 to 30 degrees. The roll and / or the pitch cycle frequency threshold may be in the range of 0 to 0.2 hertz; optionally, approximately 0.1 hertz. The heave acceleration threshold may be in the range of 0 to 0.5 g; optionally, 0.1 to 0.3 g, for example, approximately 0.2 g, where g is the gravitational acceleration. The heave displacement threshold may be in the range of 0.1 to 4 meters; optionally 0.1 to 2 meters. When the control module 104 determines that at least one determined maximum motion of the cargo 12 exceeds its corresponding motion threshold, the control module 104 is configured to generate alert data, and send the generated alert data to the satellite communication module 108. By 'generate alert data', it is intended to mean that the control module 104 collates data determined previously by, for example, the control module 104 and / or the sensor arrangement 106, and / or produces new data (e.g. an alert message). The satellite communication module 108 is configured to transmit the generated alert data to the remote device(s) 102. The alert data alerts a stakeholder to the fact that the cargo 12 has exceeded a predetermined motion threshold, which enables them to act accordingly. In some embodiments, the alert data includes data based on the motion data determined by the motion sensor arrangement 106a over the monitoring period (e.g. raw and / or processed motion data). For example, the alert data may include data corresponding to the one or more determined maximum motions of the cargo 12. This may help a stakeholder to determine the risk of damage having occurred to the cargo 12. The alert data may additionally or alternatively include any suitable data. For example, the alert data may include data based on the position data determined by the position sensor arrangement 106b (e.g. raw and / or processed position data). Such alert data informs a stakeholder of the location of the cargo 12 when subjected to excessive and potentially damaging motion. The control module 104 enqueues the alert data in the satellite communication module 108, which waits for a satellite to have a suitable relative position (e.g. be substantially overhead) before transmitting the enqueued alert data to said satellite for transmission to the remote device(s) 102. As such, the delay between the control module 104 determining that at least one determined maximum motion of the cargo 12 exceeds its corresponding motion threshold and the remote device(s) 102 receiving the alert data may be in the order of seconds, minutes or hours. However, even with a delay in the order of hours, the monitoring device 100 informs a stakeholder that motion criteria have not been complied with much sooner than known devices. After the alert data has been transmitted, the control module 104 receives motion data determined by the motion sensor arrangement 106a over a subsequent monitoring period (i.e. starting (e.g. immediately) after the previous monitoring period has ended), determines one or more maximum motions of the cargo 12 during the subsequent monitoring period based on said received motion data, and generates alert data when at least one determined maximum motion exceeds a corresponding predetermined motion threshold. Advantageously, processing motion data determined during monitoring periods periodically and transmitting data based on the processed motion data helps to reduce the frequency of transmissions by the satellite communication module 108 and the amount of data that needs to be transmitted, which reduces the associated costs. In some embodiments, the control module 104 may be configured to determine a wave height characteristic (e.g. significant wave height or root mean square wave height) of the water 14 during the monitoring period based on the received motion data. The wave height characteristic may be determined from the heave acceleration data (e.g. by assuming simple harmonic motion of the cargo 12 in the heave direction). In such embodiments, the control module 104 may be configured to compare the determined wave height characteristic of the water 14 to a corresponding predetermined wave height characteristic threshold, and generate the alert data when said threshold is exceeded. The alert data may include the determined wave height characteristic. In embodiments in which the wave height characteristic is the significant wave height of the water 14, the corresponding threshold may be in the range of 0.1 to 4 meters; optionally 0.1 to 2 meters. In some embodiments, the control module 104 may be configured to determine one or more time-averaged motions of the cargo 12 during the monitoring period based on the received motion data. By'a time-averaged motion of the cargo 12', it is intended to mean a single parameter corresponding to a time-average over the monitoring period of the received motion data corresponding to a displacement, speed, acceleration or motion cycle frequency in surge, sway, heave, roll, pitch or yaw. In such embodiments, the control module 104 may be configured to generate the alert data when at least one of the determined time-averaged motions of the cargo 12 exceeds a corresponding predetermined threshold, and send the generated alert data to the satellite communication module 108 for transmitting to the remote device(s) 102. In an exemplary embodiment, the control module 104 is configured to determine a time-averaged roll angle amplitude of the cargo 12 during the monitoring period based on the received motion data, and generate the alert data when the determined time-averaged roll angle amplitude exceeds a corresponding predetermined time-averaged roll angle threshold. The time-averaged roll angle threshold may be 5 degrees or more. When the cargo 12 is bulk cargo, a non-zero time-averaged roll angle amplitude may indicate listing of the watercraft 10 due to liquefaction of the cargo 12. As such, sending alert data to the remote device(s) 102 when such a non-zero time-averaged roll angle amplitude is detected enables a remote user to inform an operator of the watercraft 10 so that they can take mitigative action if necessary. The control module 104 is configured to periodically generate status data, and send the generated status data to the satellite communication module 108 for transmission to the remote device(s) 102 in a similar manner to the alert data. In the illustrated embodiment, the control module 104 generates the status data periodically, each time a predetermined status period elapses. The status period may correspond to a multiple of the monitoring period. For example, the status period may correspond to two or more monitoring periods (e.g. twelve monitoring periods). The status data may include data corresponding to one or more of: a time at which the data was determined, a position of the device (e.g. position data determined by the position sensor arrangement 106b), a power status of the device (e.g. a battery voltage), and a temperature of the device. The status data helps to inform a stakeholder about the health of the monitoring device 100. In some embodiments, the position sensor arrangement 106b may be predominantly in a low-power mode (e.g. a hibernate mode) in which it consumes little or no electrical power and in which it cannot determine the position data, and may periodically enter a high-power mode (e.g. an operate mode) in which it consumes relatively more electrical power and in which it determines the position data. For example, the position sensor arrangement 106b may only enter the high-power mode once within each monitoring period for a period shorter than the monitoring period. Advantageously, this helps to reduce the power consumed by the monitoring device 100. The short-range wireless communication module 114 is configured for wirelessly communicating with the watercraft 10 (e.g. the bridge or wheelhouse 10a, or a control room of the watercraft 10), for example via one or more suitable wireless protocols such as LoRaR™, BluetoothR™, ZigbeeR™, Wi-FiR™. The short-range wireless communication module 114 includes an antenna 114a for transmitting radios signals to, and receiving radio signals from, the watercraft 10. In alternative embodiments, the short-range wireless communication module 114 may only be suitable for transmitting radio signals. In the illustrated embodiment, the control module 104 is configured to send the generated alert data and status data to the short-range wireless communication module 114, for transmitting to the watercraft 10. Advantageously, this may enable an operator of the watercraft 10 to take action (e.g. reduce the speed of the watercraft 10) to reduce the motion of the cargo 12. In alternative embodiments (not shown), the monitoring device 100 may not include the short-range wireless communication module 114. The control module 104 is configured to store record data in the memory module 112. The record data may be based on one or more of: motion data received from the motion sensor arrangement 106a, position data received from the position sensor arrangement 106b, data received from the power supply arrangement 110, data received from the satellite communication module 108, and / or data received from the short-range wireless communication module 114. The record data may include time data identifying when events occurred. In some embodiments, the record data may include data corresponding to one or more of: the position of the device 100 (e.g. latitude and longitude); a speed (e.g. overground) of the device 100 (e.g. determined by the motion sensor arrangement 106a and / or the position sensor arrangement 106b); a heading of the device 100; a number of satellites used by the position sensor arrangement 106b to determine the position of the device 100; maximum surge, sway and / or heave accelerations / speeds / displacements / cycle frequencies for each monitoring period; mean surge, sway and / or heave accelerations / speeds / displacements for each monitoring period; maximum pitch, roll and / or yaw angle amplitudes for each monitoring period; maximum pitch, roll and / or yaw angular rate amplitudes; pitch, roll and / or yaw peak frequencies; a temperature of the device 100 (e.g. a temperature of the control module 104 determined via a suitable sensor); a power storage level of the power storage module 110a (e.g. a battery voltage); and / or a power generation level of the power generation module 110b (e.g. a voltage of the solar panel 120). The control module 104 may additionally or alternatively be configured to store any suitable record data in the memory module 112. The status data and alert data previously described may include any of the foregoing record data. The control module 104 is configured to receive a command from the remote device(s) 102 via the satellite communication module 108 and from the watercraft 10 via the short-range wireless communication module 114. For example, such a command may be a request for record data (e.g. specified record data occurring at a specified time or within a specified time range), or a command from the remote device(s) 102 to send data (e.g. a message) to the watercraft 10 or vice versa. In alternative embodiments, the control module 104 may be configured to receive such commands from only one of the satellite communication module 108 or the short-range wireless communication module 114. In response to a request from the remote device(s) 102 or the watercraft 10 for record data, the control module 104 is configured to retrieve the record data specified in the command from the memory module 112. The control module 104 then sends data based on the retrieved record data (e.g. raw and / or processed retrieved record data) to the satellite communication module 108 for transmission to the remote device(s) 102, or the short-range wireless communication module 114 for transmission to the watercraft 10. As such, the stakeholder and the operator of the watercraft 10 can remotely obtain specific record data corresponding to the monitoring device 100 and the cargo 12. In alternative embodiments (not shown), the monitoring device 100 may be configured to send and / or receive data to / from a further device via wired communication. In such embodiments, the monitoring device 100 may comprise a suitable hardware interface, such as a suitable socket or port (e.g. a USB port), for connecting the control module 104 to the further device via a wire or cable for enabling communication between the control module 104 and the further device. For example, the further device may receive record data from the memory module 112 via said hardware interface. Such a configuration of the monitoring device 100 may enable a crew member of the watercraft 10 to obtain data from, and / or provide data to, the monitoring device 100 during transportation of the cargo 12. The power supply arrangement 110 Is configured to independently supply power to the monitoring device 100. By 'independently supply power', it is intended to mean that the power supply arrangement 110 supplies power to the monitoring device 100 without itself receiving power from any other device. Such a power supply arrangement 110 helps to increase the flexibility for where the monitoring device 100 can be located since an external power supply is not required. Moreover, the power supply arrangement 110 reduces the dependency of the cargo stakeholders on the owners / operators of the watercraft 10. The power supply arrangement 110 includes a power storage module 110a (e.g. one or more (e.g. lead acid) batteries) configured to supply power to the monitoring device 100. In the illustrated embodiment, the power storage module 110a supplies power to the device 100 via the control module 104, but may also supply power directly to one or more other components of the device 100 in alternative embodiments. The power supply arrangement 110 includes a power generation module 110b. In the illustrated embodiment, the power generation module 110b generates electrical power and supplies the generated electrical power to the power storage module 110a (e.g. charges one or more batteries). Additionally, or alternatively, the power generation module 110b may supply power directly to other components of the monitoring device 100 (e.g. the control module 104). In alternative embodiments (not shown), the monitoring device 100 may be configured to additionally or alternatively receive power from another device (e.g. via a wire or cable connected to the monitoring device 100). In such embodiments, the monitoring device 100 may not include the power storage module 110a and / or the power generation module 110b. With reference to Figure 3 the power generation module 110b includes a solar panel 120 (i.e. a photovoltaic cell). In alternative embodiment (not shown), the power generation module 110b may additionally or alternatively include any suitable power generation device (e.g. a wind turbine, a motion powered energy generator, and / or a thermoelectric generator). As shown in Figure 3, the monitoring device 100 includes a housing 122. The solar panel 120 is mounted to an exterior surface of the housing 122 so as to receive light (e.g. from the sun). In the illustrated embodiment, the control module 104, the sensor arrangement 106, the satellite communication module 108 (including the antenna 108a), the power storage module 110a, the memory module 112, and the short-range wireless communication module 114 are wholly housed within the housing 122, which helps to protect these components from damage caused by the external environment. In the illustrated embodiment, the housing 122 is a waterproof housing, i.e. the housing 122 is configured to inhibit water ingress, which helps to prevent the components housed therein from water damage. The housing 122 includes first and second parts 122a, 122b that are releasably secured together via a plurality of fasteners (not shown), such as screws or bolts, received in corresponding fastening points 124 in the first and second parts 122a, 122b. In Figure 3, eight fasteners are received in eight pairs of fastening points 124 to secure first and second parts 122a, 122b to each other. The first and second parts 122a, 122b are formed from plastic. The housing 122 includes a seal member (e.g. a flexible polymeric gasket) between the first and second parts 122a, 122b, to inhibit water ingress. In alternative embodiments (not shown), the housing 122 may have any suitable configuration, and may be formed from any suitable material(s). In such embodiments, the housing 122 may not be waterproof (e.g. the housing 122 may instead be water-resistant). The housing 122 includes a mounting arrangement 126 for mounting the housing 122 to the watercraft 10 or the cargo 12. In the illustrated embodiment, the mounting arrangement 126 includes a plurality of recesses 128 in the housing 122 configured to receive a mounting member (e.g. a cable, a wire, or a cable tie) therethrough so as to mount the housing 122 to the watercraft 10 or the cargo 12 via said mounting member. In alternative embodiments (not shown), the housing 122 may include any suitable mounting arrangement or no mounting arrangement (e.g. a separate mounting arrangement may be used to mount the housing 122 to the watercraft 10 or cargo 12). In the illustrated embodiment, the monitoring device 100 includes a key-operated switch 130 configured to selectively power on or off the device 100 (e.g. the control module 104). The key-operated switch 130 is accessible from outside of the housing 122 to enable a user to power on or off the device 100 without having to open the housing 122. In alternative embodiments (not shown), the monitoring device 100 may include any suitable switch to selectively power on or off the device 100. The monitoring device 100 includes a power status indicator 132 configured to indicate whether the device 100 is powered on or off. In the illustrated embodiment, the power status indicator 132 includes a plurality of LEDs arranged around the switch 130, which emit light for a predetermined period of time when the device 100 is first powered on. Alternatively, the power status indicator 132 may have any suitable configuration, and for example, may include any suitable light source. Figure 4 shows a flowchart of an exemplary process carried out by the control module 104. In step SI, the monitoring period is started (e.g. the control module 104 stores a monitoring period start time). In subsequent step S2, the control module 104 receives motion data determined by the motion sensor arrangement 106a during the monitoring period. In the illustrated embodiment, the control module 104 receives the motion data immediately after it is determined by the motion sensor arrangement 106a. In alternative embodiments, the control module 104 may instead receive a set of motion data after the monitoring period has ended. In subsequent step S3, the control module 104 determines whether the monitoring period has elapsed. If the monitoring period has not elapsed ('No'), the process returns to step S2. Otherwise, if the monitoring period has elapsed ('Yes'), the process proceeds to step S4. In step S4, the control module 104 determines the one or more maximum motions of the cargo 12 during the monitoring period based on the motion data received in step S2. In subsequent step S5, the control module 104 compares the one or more maximum motions of the cargo 12 determined during step S4 to the one or more corresponding predetermined motion thresholds. If at least one determined maximum motion exceeds its corresponding motion threshold ('Yes'), the process proceeds to step S6. If none of the one or more determined maximum motions exceed their corresponding motion threshold ('No'), the process proceeds to step S7. In alternative embodiments, in step S4, the control module 104 may additionally or alternatively determine the one or more time-averaged motions of the cargo 12 during the monitoring period based on the motion data received in step S2. Further, in subsequent step S5, the control module 104 may compare the one or more time-averaged motions of the cargo 12 determined during step S4 to the one or more corresponding predetermined thresholds. If at least one determined time-averaged motion exceeds its corresponding threshold ('Yes'), the process proceeds to step S6. If none of the one or more determined time-averaged motions exceed their corresponding motion threshold ('No'), the process proceeds to step S7. In step S6, the control module 104 generates the alert data, and enqueues the generated alert data in the satellite communication module 108 for transmission to the remote device(s) 102 via satellite communication. The control module 104 may also send the alert data to the short-range wireless communication module 114 for transmission to the watercraft 10. Subsequent to step S6, the process proceeds to step S9. In step S7, the control module 104 determines whether a command has been received from the remote device(s) 102 via the satellite communication module 108 and / or from the watercraft 10 via the short-range wireless communication module 114 (e.g. a request for record data). If it is determined that a command has been received ('Yes'), the process proceeds to step S8 in which the control module 104 processes the command (e.g. retrieves and sends the requested record data). If no command has been received, the process proceeds to step S9. In step S9, the control module 104 determines whether the status period has elapsed. If it is determined in step S9 that the status period has elapsed ('Yes'), the control module 104 generates the status data, and enqueues the generated status data in the satellite communication module 108 for transmission to the remote device(s) 102 in step S10. The control module 104 may also send the status data to the short-range wireless communication module 114 for transmitting to the watercraft 10. In step S10, the control module 104 also restarts the status period. Subsequent to step S10, the process proceeds to step SI, in which the control module 104 restarts the monitoring period (e.g. stores a new monitoring period start time). The process then proceeds to step S2 in which the control module 104 receives motion data determined by the motion sensor arrangement 106a during the new monitoring period. If it is determined in step S9 that the status period has not elapsed ('No'), the process proceeds to step SI. The process represented in Figure 4 may run until the control module 104 is powered off, or receives an instruction to end the process. In alternative embodiments (not shown), one or more steps of the process may have an alternative order, may run in parallel with one or more other steps, or may be omitted (e.g. status data may not be transmitted). Figure 5 shows a flowchart of another exemplary process carried out by the control module 104. Steps SI to S4, and S6 to S10 are identical to the corresponding steps of the process of Figure 4. In step S5a, which is subsequent to step S4, the control module 104 compares the one or more maximum motions of the cargo 12 determined during step S4 to one or more corresponding first predetermined motion thresholds, which may correspond to the one or more thresholds of the process of Figure 4. If at least one determined maximum motion exceeds its corresponding first motion threshold ('Yes'), the process proceeds to step S6. If none of the one or more determined maximum motions exceed their corresponding first motion threshold ('No'), the process proceeds to step S5b. In step S5b, the control module 104 compares the one or more maximum motions of the cargo 12 determined during step S4 to one or more corresponding second predetermined motion thresholds, which are less than the corresponding first predetermined motion thresholds. For example, each second motion threshold may be a fixed proportion (e.g. 40%, 50%, 60%, 70%, 80%, or 90%) of its corresponding first motion threshold. If at least one determined maximum motion exceeds its corresponding second motion threshold ('Yes'), the process proceeds to step S5c. If none of the one or more determined maximum motions exceed their corresponding second motion threshold ('No'), the process proceeds to step S7. In step S5c, the control module 104 generates warning data, which may include any of the alert data, status data and / or record data described above. The control module 104 sends the warning data to the satellite communication module 108 for transmitting to the remote device(s) 102, and / or to the short-range wireless communication module 114 for transmitting to the watercraft 10. The warning data warns the stakeholder and / or the operator of the watercraft 10 that at least one of the first motion thresholds (which may form part of the predetermined motion criteria described above) is close to being exceeded, enabling them to take mitigative and / or preventative action in response. Subsequent to step S5c, the process proceeds to step S9. In alternative embodiments, in steps S5a, S5b and S5c, the control module 104 may additionally or alternatively compare one or more time-averaged motions of the cargo 12 determined during step S4 to one or more corresponding first and second predetermined thresholds, and subsequently generate alert data or warning data, in a similar manner as described above.

Claims

1. A monitoring device for monitoring marine cargo, comprising:a sensor arrangement configured to determine motion data corresponding to one or more rigid body motions of the cargo;a satellite communication module for communicating with a remote device via satellite communication; anda control module configured to:receive motion data determined by the sensor arrangement over a predetermined monitoring period;determine one or more maximum motions of the cargo during the monitoring period based on the received motion data; andgenerate alert data when at least one determined maximum motion exceeds a corresponding first predetermined motion threshold,wherein the satellite communication module is configured to transmit the generated alert data to said remote device.

2. The monitoring device of claim 1, wherein the alert data comprises data based on the received motion data.

3. The monitoring device of claim 2, wherein the alert data comprises data corresponding to the one or more determined maximum motions of the cargo.

4. The monitoring device of any preceding claim, wherein the control module is configured to generate warning data when at least one determined maximum motion exceeds a corresponding second predetermined motion threshold less than the corresponding first predetermined motion threshold, and wherein:the satellite communication module is configured to transmit the generated warning data to the remote device, and / orthe monitoring device comprises a short-range wireless communication module configured to transmit the generated warning data to a watercraft transporting the cargo via wireless communication.

5. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprise one or more maximum rotation motions (e.g. in pitch, roll or yaw) of the cargo during the monitoring period; optionally, where the one or more maximum rotation motions comprise at least one maximum rotation angle amplitude, and / or at least one maximum rotation cycle frequency.

6. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprise one or more maximum linear accelerations (e.g. in surge, sway or heave) of the cargo during the monitoring period.

7. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprises at least one maximum pitch rotation motion, at least one maximum roll rotation motion, and at least one maximum heave acceleration, of the cargo during the monitoring period; optionally, wherein the determined one or more maximum motions further comprises at least one maximum heave displacement of the cargo during the monitoring period.

8. The monitoring device of any preceding claim, wherein the control module is further configured to:determine one or more time-averaged motions of the cargo during the monitoring period based on the received motion data; andgenerate alert data when at least one determined time-averaged motion exceeds a corresponding predetermined threshold;optionally, wherein said one or more time-averaged motions of the cargo comprises a time-averaged roll angle amplitude of the cargo; optionally, wherein the corresponding predetermined threshold is 5 degrees or more.

9. The monitoring device of any preceding claim, wherein the monitoring period is at least 60 seconds; optionally, wherein the monitoring period is in the range of 60 to 3600 seconds; optionally, in the range of 60 to 1800 seconds; optionally, in the range of 60 to 600 seconds.

10. The monitoring device of any preceding claim, further comprising a memory module, wherein the control module is configured to store record data determined by the control module in the memory module, receive a request for record data from a remote device via the satellite communication module, and retrieve record data from the memory module in response, wherein the satellite communication module is configured to transmit data based on the retrieved record data to said remote device; optionally, wherein the record data is based on the received motion data.

11. The monitoring device of any preceding claim, wherein the sensor arrangement is configured to determine position data corresponding to a position of the monitoring device, and wherein the alert data comprises data based on the determined position data.

12. The monitoring device of any preceding claim, further comprising a short-range wireless communication module for communicating with a watercraft transporting the marine cargo via wireless communication, wherein the short-range wireless communication module is configured to transmit the alert data to said watercraft.

13. The monitoring device of any preceding claim, wherein the control module is configured to periodically generate status data (e.g. corresponding to one or more of a time, a position of the device, a power status of the device, and a temperature of the device), and wherein the satellite communication module is configured to transmit the status data to a remote device.

14. The monitoring device of any preceding claim, further comprising a power supply arrangement configured to independently supply power to the device; optionally, wherein the power supply arrangement comprises a power storage module (e.g. one or more batteries).

15. The monitoring device of claim 14, wherein the power supply arrangement comprises a power generation module (e.g. a solar panel).

16. The monitoring device of any preceding claim, further comprising a (e.g. waterproof or water resistant) housing, wherein the sensor arrangement, the control module, and the satellite communication module are at least partially housed within the housing.

17. The monitoring device of claims 15 or 16, wherein the housing comprises a mounting arrangement for mounting the housing to a watercraft or the cargo.

18. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprises a maximum roll angle amplitude of the cargo during the monitoring period, and wherein the corresponding motion threshold is in the range of 15 to 35 degrees; optionally, 20 to 30 degrees.

19. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprises a maximum pitch angle amplitude of the cargo during the monitoring period, and wherein the corresponding motion threshold is in the range of 2.5 to 35 degrees; optionally, 10 to 30 degrees.

20. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprises a maximum roll and / or pitch cycle frequency of the cargo during the monitoring period, and wherein the corresponding motion threshold is in the range of 0 to 0.2 hertz; optionally, approximately 0.1 hertz.

21. The monitoring device of any preceding claim, wherein the determined one or more maximum motions comprises a maximum heave acceleration of the cargo during the monitoring period, and wherein the corresponding motion threshold is in the range of 0 to 0.5 g; optionally, 0.1 to 0.3 g, for example, approximately 0.2 g.

22. A monitoring device for monitoring marine cargo, comprising:a sensor arrangement configured to determine motion data corresponding to one or more rigid body motions of the cargo, and / or position data corresponding to a position of the device;a satellite communication module for communicating with a remote device via satellite communication;a control module; anda housing, such as a waterproofer water-resistant housing,wherein the satellite communication module comprises an antenna,wherein the control module is configured to generate data based on the data determined by the sensor arrangement,wherein the satellite communication module is configured to transmit the generated data to said remote device via the antenna, andwherein the sensor arrangement, the satellite communication module and the control module are wholly housed within the housing.

23. The monitoring device of claim 22, further comprising a power supply arrangement configured to independently supply power to the device, wherein the power supply arrangement is at least partially housed within the housing; optionally, wherein the power supply arrangement comprises a solar panel mounted to an exterior surface of the housing.

24. An assembly comprising the monitoring device of any preceding claim mounted to an item of cargo (e.g. containerised or project cargo) or a watercraft.

25. A method for monitoring marine cargo, comprising:receiving motion data corresponding to one or more rigid body motions of the cargo determined over a monitoring period;determining one or more maximum motions of the cargo during the monitoring period based on the received motion data;generating alert data when at least one determined maximum motion exceeds a corresponding predetermined motion threshold; and5 transmitting the alert data to a remote device via satellite communication.27

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