A system and method for providing data indicative of grab usage of a mechanical grab

Abstract

A system and method for providing data indicative of grab usage of a mechanical grab A system and method for providing data indicative of grab usage of a mechanical grab (2), optionally using a grab data measurement unit (4) and a grab monitoring system (6). The grab data measurement unit comprises an atmospheric pressure sensor (8), and optionally a processor (10) and a first communication unit (12). The grab data measurement unit is attached or attachable to the mechanical grab. The method comprises sensing, optionally using the atmospheric pressure sensor, ambient air pressure at the mechanical grab. The method comprises monitoring the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab. The method optionally comprises determining, using the processor or the grab monitoring system, grab height data from the measured air pressure. The method optionally comprises transferring, using the first communication unit, data indicative of grab usage to the second communication unit (7). Data indicative of grab usage optionally comprises and / or is determined from the determined grab height data.

Description

[0001] P137283PC00

[0002] Title: A system and method for providing data indicative of grab usage of a mechanical grab

[0003] Field of the invention

[0004] The present invention relates to the field of mechanical grabs, in particular mechanical grabs that are suspended from a crane through cables, such as a cable operated clamshell grab. In particular, the invention relates to the field of grab usage data of a mechanical grab. More in particular, the invention relates to a grab data collection system and a method for providing data indicative of grab usage of a mechanical grab, and a grab data measurement unit and grab monitoring system, a use of an atmospheric pressure sensor on a mechanical grab, and a mechanical grab provided with a grab data measurement unit attached thereto.

[0005] Background

[0006] Handling dry bulk such as discharging ships carrying bulk is known to be performed using a mechanical grab. Such a mechanical grab can transfer a large amount of product at a time. The product can be ore, coal or other types of bulk commodities. The bulk terminal is in general a quite dusty and harsh environment. Therefore, mechanical grabs have been designed to become more robust, thereby increasing the lifetime and reducing the amount of required maintenance. Many components of the grab are therefore mechanical, and the use of electrical components is minimized and generally avoided as they typically require electrical wiring and / or power sources that are more vulnerable to break in case of collisions and / or electrical components have a risk of being damaged when subjected to dust and (salt) water. Nevertheless, such a mechanical grab still requires maintenance during its lifetime.

[0007] It is known to schedule maintenance at predetermined moments in time during the life span of the mechanical grab, for example every two or three months. At the time of a scheduled maintenance, a visual inspection can additionally be performed, e.g. by a mechanic or technician. Wear, tearing and / or other damage that is not visible from the outside is not always noticed during such a visual inspection process. The load and intensity of grab use over time are often unknown to grab owners, such that they are unaware of the type of maintenance the mechanical grab requires at which moment in time. As the grab usage is not taken into account in scheduling maintenance, the grab has sometimes hardly been used during the time that passed since the previous scheduled maintenance and does not yet require maintenance, or, on the contrary, it has been used a lot and needed maintenance earlier.

[0008] Once more insight can be gained in the required maintenance and the moment in time the grab requires maintenance, this can aid in increasing the lifetime of the grab even more. In addition, such insight can result in the possibility of predicting the time period in which maintenance is required in order to prevent downtime, and / or the option of scheduling predictive maintenance in advance. By scheduling predictive maintenance in advance, unexpected maintenance could be prevented, thereby reducing the overall required amount of maintenance. Therefore it is desired to provide data indicative of grab usage of the mechanical grab that can aid in increasing the lifetime of the grab, reduce the overall required amount of maintenance of the grab and / or reduce the amount of downtime of the grab, while maintaining the capacity and functionality of the grab.

[0009] To assist in the above, applicant NEMAG has proposed EP 1671918 in a system and method for providing data indicative of grab usage of a mechanical grab including a first grab data communication unit, arranged as a transmitter or transponder, that is attached to the grab and a second communication unit disposed along the path of the grab for wireless communication with the first communication unit on the grab. When the grab passes the second communication unit, it detects the first unit and consequently, the grab. As a result, cycles of the grab are determined for optimizing use and maintenance. An advantage of this system is that the first communication unit on the grab may have low power consumption, and hence long battery life. A disadvantage of the system is that the second communication unit needs to be disposed along the path or the grab.

[0010] Later publications EP1958915 by ISAM and EP4114779 by Verstegen disclose a system and method for providing data indicative of grab usage of a mechanical grab including a first grab data communication unit arranged on the grab with which motion of the grab is continuously monitored using an inertial measurement sensor. An advantage of this system is that communication unit does not need to be disposed along the path or the grab. A disadvantage of the system is that such inertial measurement sensing is power intensive. It is also data intensive, which requires data processing on the grab. These disadvantages cause the first data communication unit on the grab to have a relatively short battery life, and / or require a relatively high energy storage capacity on the grab. A relatively high energy storage capacity, i.e. relatively large amount of batteries, lead to an increased safety risk due to an increased risk of the occurrence of fire.

[0011] Summary

[0012] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art. More in general, it is an object to provide an improved grab data collection system and method for providing data indicative of grab usage of a mechanical grab, an improved grab data measurement unit and grab monitoring system, a use of an atmospheric pressure sensor on a mechanical grab, and an improved mechanical grab provided with a grab data measurement unit attached thereto. It is also an object of the present invention to provide alternative structures which are more sustainable, have an increased lifetime, require less maintenance, and which are more cost efficient with respect to their usage. Alternatively it is an object of the invention to at least provide the public with a useful choice.

[0013] To this end the invention provides for a method for providing data indicative of grab usage of a mechanical grab, a grab data collection system configured for providing data indicative of grab usage of a mechanical grab, a mechanical grab provided with a grab data measurement unit attached thereto, a grab data measurement unit attachable to a mechanical grab that include an atmospheric pressure sensor on the mechanical grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab. Use of an atmospheric pressure sensor on a mechanical grab to sense ambient air pressure at the grab allows the first data communication unit on the grab to have low power consumption and hence a long battery life, without need for the second communication unit to be disposed along the path or the grab. Atmospheric pressure sensing at the grab also provides for low data intensity, which allows data to be transferred as raw data, i.e without need for processing on the grab, which simplifies the components and increases battery life.

[0014] In a first aspect, the invention provides for a method for providing data indicative of grab usage of a mechanical grab, comprising sensing ambient air pressure at the mechanical grab and monitoring the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab.

[0015] In a second aspect, the invention provides for a grab data collection system configured for providing data indicative of grab usage of a mechanical grab, wherein the grab data collection system comprises a grab data measurement unit and a grab monitoring system, wherein the grab data measurement unit is attached or attachable to the mechanical grab, the grab data measurement unit comprising an atmospheric pressure sensor configured for sensing ambient air pressure at the mechanical grab, and the grab monitoring system being arranged to monitor the sensed ambient air pressure over time so as to detect changes in sensed air pressure that are indicative of hoist of the grab.

[0016] In a third aspect, the invention provides for a grab data measurement unit as comprised in the grab data collection system as described.

[0017] In a fourth aspect, the invention provides for a grab monitoring system as comprised in the grab data collection system as described.

[0018] In a fifth aspect, the invention provides for the use of an atmospheric pressure sensor on a mechanical grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab.

[0019] In a sixth aspect, the invention provides for a mechanical grab provided with a grab data measurement unit attached thereto, the grab data measurement unit including an atmospheric pressure sensor attached to the grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab.

[0020] In a seventh aspect, the invention provides for a grab data measurement unit attachable to a mechanical grab, the grab data measurement unit including an atmospheric pressure sensor to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab. Within this context, hoist is defined as a change in height position of the grab due to lifting and / or lowering of the grab, in particular by respective tensioning and / or slackening cables on which the grab is suspended.

[0021] Monitoring ambient air pressure may include storing air pressure data on the grab, processing air pressure data on the grab, transferring air pressure data and / or processed air pressure data from the grab, in particular transmitting air pressure data and / or processed air pressure data from the grab or reading air pressure data and / or processed air pressure data from the grab. Detecting changes in air pressure may include logging ambient air pressure sensed at the grab and determining changes from the log, logging changes in ambient air pressure sensed at the grab, and / or or signaling changes in ambient air pressure sensed at the grab.

[0022] Changes in air pressure that are indicative of hoist may e.g. be changes in ambient pressure that level out within a limited time frame, e.g. a time frame of a limited number of minutes, e.g. 10, 5, 3 or 1 minutes, preferably within a limited number of seconds, e.g. 30, 15 or 10 seconds, or within a second, or e.g. be defined as changes in ambient air pressure that have an absolute gradient of at least 12, 1.2 or 0.12 Pascal per T1 seconds. In said absolute gradient, T1 indicates a time period of e.g. 10, 5, 3, or 1 seconds between ambient air pressure measurements measured by the atmospheric pressure sensor at the grab. A change in air pressure of 12 Pascal per T1 seconds can be indicative of hoist of the grab in the order of approximately one or more meters. A measured air pressure change of 0.12 Pascal can be indicative of hoist of the grab in the order of approximately one or more centimeters. The atmospheric pressure sensor therefore requires a measurement accuracy of at least 12 Pascal per T1 seconds, preferably 1.2 Pascal per T1 seconds, and more preferably 0.12 Pascal per T1 seconds.

[0023] Elaborating on the first aspect, a method for providing data indicative of grab usage of a mechanical grab is provided, optionally using a grab data measurement unit and a grab monitoring system. The grab data measurement unit comprises an atmospheric pressure sensor, and optionally a processor and / or a first communication unit. The grab monitoring system optionally comprises a second communication unit. The grab data measurement unit is attached to the mechanical grab. The method comprises sensing, optionally using the atmospheric pressure sensor, ambient air pressure at the mechanical grab. It will be appreciated that the step of sensing ambient air pressure at the mechanical grab can be performed using a single atmospheric pressure sensor comprised in the grab data measurement unit. The atmospheric pressure sensor can comprise an analog or digital atmospheric pressure sensor, such as a barometer. The method comprises monitoring, optionally using the grab monitoring system, the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab. The method can comprise detecting a change in sensed ambient air pressure values over time. Optionally, the method comprises determining, using the processor or the grab monitoring system, grab height data from the sensed air pressure. This may either be carried out on the grab, or at the grab monitoring system. The determining can comprise comparing the sensed air pressure with a predetermined air pressure profile. The predetermined air pressure profile can comprise sensed air pressures varying over the different heights over which the grab typically moves during a movement cycle. The movement cycle comprises a movement of the grab from a loading position, in which product is grabbed by the grab, to an unloading position, in which product is unloaded from the grab. The loading position can be vertically below the unloading position, or vice versa. Alternatively, the loading and unloading positions are approximately at the same vertical position, and the movement cycle of the grab comprises vertical movement in order to move between the loading and unloading position, for example if the grab has to be lifted over the edge of hatch coaming. Either way, the variety in ambient air pressures sensed at different locations on the movement cycle of the grab is indicative of a varying vertical position of the grab. The movement cycle can alternatively comprise the back and forth movement of the grab from the loading position to the unloading position and back to the loading position, i.e. provided that this movement cycle includes at least partially a vertical displacement of the grab. The movement cycle can comprise at least one of translational movement and rotational movement of the grab. One movement cycle can comprise a plurality of movement path sections. At least two movement path sections can at least partially overlap. The predetermined air pressure profile can include air pressure measurements at different weather conditions. The method can further comprise accessing the weather forecast data in order to more accurately compare the measured air pressure to the predetermined air pressure profile.

[0024] The method comprises transferring, using the first communication unit, data indicative of grab usage to the second communication unit. The first communication unit can e.g. comprise a transmitter and / or a transceiver. The data indicative of grab usage can be transferred to the second communication unit wirelessly. The second communication unit can e.g. comprise a receiver and / or a transceiver. Optionally, the data indicative of grab usage comprises and / or is determined from the determined grab height data. The data indicative of grab usage can be determined from the determined grab height data using the grab monitoring system. The data indicative of grab usage can be determined from the determined grab height data using the processor instead.

[0025] Optionally, the grab data measurement unit further comprises a battery. The battery can be configured for powering the other components of the grab data measurement unit, i.e. for powering the atmospheric pressure sensor, the processor and the first communication unit. The battery can be configured for directly supplying power to the processor. The components of the grab data measurement unit can alternatively or additionally be powered by an external power source, such as one or more additional batteries, an additional energy harvesting or generating system such as a solar panel and / or a system that converts kinetic energy, e.g. of the grab, into electrical energy. The external power source can be connectable to the grab data measurement unit. The method can comprise powering, using the battery and / or the external power source, the other components of the grab data measurement unit. The components of the grab data measurement unit preferably have a relatively low power consumption. Optionally, the data indicative of grab usage comprises data indicative of a change in height of the grab. In case the data indicative of grab usage comprises data indicative of a change in height of the grab, a sensed change in air pressure can be indicative of hoist. The change in height can be determined from the determined grab height data using the grab monitoring system. The change in height can be determined from the determined grab height data using the processor instead. The change in height can be determined by comparing a first sensed air pressure to a second sensed air pressure separated by a predetermined time period. The second sensed air pressure is sensed by the atmospheric pressure sensor after the first sensed air pressure. An air pressure difference between the first sensed air pressure and the second sensed air pressure can be used to determine the change in height of the grab. The predetermined time period can comprise a couple of minutes, e.g. 10, 5, 3 or 1 minutes, and preferably seconds, e.g. 30, 15 or 10 seconds, or a second. Optionally, the method further comprises a step of determining, using the processor or the grab monitoring system, the occurrence of at least a predetermined change in height, e.g. in a predetermined time period. If the occurrence of at least a predetermined change in height is determined, the accompanying sensed change in air pressure is indicative of hoist. The determining can comprise determining whether the change in height of the grab exceeds the predetermined change in height. The predetermined change in height can comprise a positive or negative height difference the grab at least requires to move during one movement cycle. The predetermined time period between the first and second sensed air pressures can be shorter than or equal to the minimum time period the grab requires for completing one movement cycle. Optionally, the step of determining, using the processor or the grab monitoring system, the occurrence of at least a predetermined change in height comprises determining the occurrence of at least a predetermined relative change in height. The predetermined relative change in height is a measure of the relative height difference between consecutive movements of the grab. A relatively large height difference occurring later in time than a relatively small height difference could for example indicate a movement cycle of the grab, whereas the relatively small height difference will likely not be indicative of a movement cycle of the grab. If the occurrence of at least a predetermined relative change in height is determined, the accompanying sensed relative change in air pressure is indicative of hoist. The determining can comprise determining whether the relative change in height of the grab exceeds the predetermined relative change in height. The predetermined relative change in height can comprise a positive or negative relative height difference that can be used to distinguish between the change in height the grab at least requires to move during one movement cycle, and a change in height that would be too small for the grab to complete a movement cycle. The predetermined time period between the sensed relative changes in air pressure can be shorter than or equal to the minimum time period the grab requires for completing one movement cycle.

[0026] Alternatively or additionally, the method can further comprise a step of determining, using the processor or the grab monitoring system, the occurrence of at least a predetermined gradient of change in height over time. The sensed change in air pressure, e.g. due to a change in height of the grab, can be indicative of hoist when changes in ambient air pressure exceed the predetermined gradient of change in height over time. The predetermined gradient can e.g. comprise an absolute gradient of at least 12, 1.2 or 0.12 Pascal per T1 seconds. In said absolute gradient, T1 indicates a time period of e.g. 10, 5, 3, or 1 seconds between ambient air pressure measurements measured by the atmospheric pressure sensor at the grab.

[0027] Optionally, the step of transferring comprises transferring the determined grab height data, and / or sensed air pressure, to the grab monitoring system. The grab height data and / or sensed air pressure can be considered as being raw data and / or primary data in this context, as additional steps are required in processing of the grab height data, and / or sensed air pressure, in order for the data to provide an operator with valuable insights related to usage of the grab, lifetime indicators and required maintenance. The grab height data and / or sensed air pressure, i.e. the primary data, have not been subjected to processing, e.g. to remove outliers, measurement errors or data entry errors.

[0028] Optionally, the method further comprises determining, after the step of transferring, further data indicative of grab usage. The further data indicative of grab usage comprises data indicative of movement cycles of the grab. The data indicative of movement cycles of the grab can be determined using the grab monitoring system or the processor. It will be appreciated that the data indicative of movement cycles of the grab can comprise determined changes in grab height, and / or changes in sensed air pressure, that are indicative of hoist of the grab.

[0029] Optionally, the step of determining further data indicative of grab usage comprises detecting, using the processor or the grab monitoring system, an amount of movement cycles of the grab over time.

[0030] Optionally, the method further comprises a step of measuring, using a temperature sensor attached to the grab, air temperature at the mechanical grab over time. The step of determining grab height data can comprise determining, from the measured air pressure and air temperature, using the processor or the grab monitoring system, grab height data. The temperature sensor can be integral with the atmospheric pressure sensor. The air pressure difference between air pressures measured subsequently can be influenced by changing local weather conditions. The measured air temperature at these time instances can be used to compensate for this change in weather conditions.

[0031] Optionally, the method further comprises measuring, using at least one distance measurement sensor each being attached at or near a respective one of at least two movable parts of the grab, the distance between bulk material inside the grab and the distance measurement sensor when the at least two movable parts of the grab are closed. A plurality of distance measurement sensors can be used for measuring the distance between bulk material inside the grab and the respective distance measurement sensor. Each of the plurality of distance measurement sensors can be attached at or near a respective first movable part or second movable part of the at least two movable parts of the grab. At least one distance measurement sensor can be attached to a beam or rod positioned vertically above the at least two movable parts of the grab, such that the at least one distance measurement sensor is directed at the inside of the grab when its at least two movable parts are closed. The method can further comprise determining, using the processor or the grab monitoring system, from the measured distance between the material and the sensor, the amount of material inside the grab.

[0032] Optionally, the method further comprises measuring, using at least one load shackle, load cell and / or strain gauge attached at or near one of at least two movable parts of the grab, the amount of material inside the grab when the at least two movable parts of the grab are closed.

[0033] Optionally, the grab data measurement unit comprises an accelerometer. The method can comprise measuring, using the accelerometer, grab acceleration data of the grab over time. The method can further comprise detecting, from the measured grab acceleration data, using the processor or the grab monitoring system, a collision between the grab and at least one of a ship, quay, crane or bulk material. The method can further comprise detecting, from the measured grab acceleration data, using the processor or the grab monitoring system, an angle at which the grab lands on the material. The angle between the grab and the material can be used in determining data indicative of grab usage. Optionally, the method further comprises a step of measuring, using a GPS sensor, location data of the grab over time. The location data can be used to locate the grab, for example if its location is to be more exactly known.

[0034] Optionally, the method comprises detecting, from the grab height data, using the processor, the occurrence of grab movement. The method can comprise controlling, using the processor, activating and / or inactivating of the GPS sensor and / or the first communication unit over time based on the grab movement. Controlling activating and / or inactivating of the GPS sensor and / or first communication unit over time based on the grab movement can reduce power consumption while maintaining the required data density at times of grab movement.

[0035] Optionally, the step of controlling further comprises inactivating, using the processor, when for at least a predetermined time period the occurrence of grab movement is absent, after measuring the location data, the GPS sensor and / or the first communication unit. The step of controlling can further comprise activating, using the processor, when for at least a predetermined time period the occurrence of grab movement is detected, the GPS sensor and / or the first communication unit.

[0036] Optionally, the grab monitoring system is provided remote from the grab, such as at the quay, at a crane, on shore or in a workplace or office.

[0037] Optionally, the step of transferring further comprises storing the determined grab height data, the sensed air pressure and / or data indicative of grab usage in a database in the cloud. The determined grab height data can alternatively or additionally be processed in the cloud for providing data indicative of grab usage of the mechanical grab.

[0038] Optionally, the step of transferring is performed after a predetermined time period and / or after at least a predetermined change in height is determined. The predetermined time period can comprise a predetermined amount of minutes, hours, a part of the day, a day, or a plurality of days.

[0039] Optionally, the method comprises a step of processing, prior to the transferring, the determined grab height data and / or sensed air pressure. The transferring can comprise transferring said processed grab height data and / or air pressure to the grab monitoring system. Processing prior to transferring can reduce the power consumption of the first communication unit by reducing the quantity of data.

[0040] Optionally, the method comprises determining, using the processor or the grab monitoring system, that an event occurs when a predetermined change in height within a predetermined time interval exceeds a predetermined first threshold, a collision occurs, or a closing and / or opening occurs. The method can further comprise controlling, using the processor or the grab monitoring system, the first communication unit for transferring more data per unit time in respect of the event, than in respect of periods of time not associated with an event.

[0041] Optionally, the method further comprises resetting, using the processor or the grab monitoring system, the detected amount of movement cycles of the grab movement, in response to a user input.

[0042] Optionally, the accelerometer is attached to one of at least two movable parts of the grab. The method can comprises measuring, using the accelerometer, part acceleration data of said one of the at least two movable parts of the grab over time. The method can comprise detecting, from the measured part acceleration data, using the processor, a closing and / or opening of the one movable part of the grab with respect to the other. The method can comprise providing, after detecting the closing and / or opening of the one movable part of the grab with respect to the other, a lubricant to a rotatable part of the grab using a pump and / or a valve during and / or after the closing and / or opening. A plurality of accelerometers can be used for measuring part acceleration data, each accelerometer of the plurality of accelerometers can be attached to a respective first movable part or second movable part of the at least two movable parts of the grab.

[0043] Optionally, the step of providing the lubricant is performed after the detected amount of movement cycles of the grab movement exceeds a predetermined second threshold. Elaborating on the above mentioned second and further aspects of the invention, a grab data collection system may be provided that is configured for providing data indicative of grab usage of a mechanical grab. The grab data collection system comprises a grab data measurement unit and a grab monitoring system. The grab data measurement unit is attached or attachable to the mechanical grab. The grab data measurement unit comprises an atmospheric pressure sensor configured for sensing air pressure at the mechanical grab over time. The grab monitoring system is arranged to monitor the sensed ambient air pressure over time so as to detect changes in sensed air pressure that are indicative of hoist of the grab. The grab data measurement unit optionally comprises a processor. The processor or the grab monitoring system is configured for determining grab height data from the sensed air pressure. The grab data measurement unit optionally comprises a first communication unit. The grab monitoring system optionally comprises a second communication unit. The first communication unit can be configured for transferring data indicative of grab usage to the second communication unit. The first communication unit can e.g. comprise a transmitter and / or a transceiver. The second communication unit can e.g. comprise a receiver and / or a transceiver. The data indicative of grab usage optionally comprises and / or is determined from the determined grab height data.

[0044] Optionally, the data indicative of grab usage comprises data indicative of a change in height of the grab.

[0045] Optionally, the processor or the grab monitoring system is configured for determining the occurrence of at least a predetermined change in height. Optionally, the transferring comprises transferring the determined grab height data, and / or sensed air pressure, to the grab monitoring system.

[0046] Optionally, the data indicative of grab usage comprises data indicative of movement cycles of the grab. It will be appreciated that the data indicative of movement cycles of the grab can comprise determined changes in grab height, and / or changes in sensed air pressure, that are indicative of hoist of the grab.

[0047] Optionally, the grab data measurement unit further comprises a temperature sensor attached or attachable to the grab. The temperature sensor can be configured for sensing air temperature at the mechanical grab over time. The processor or the grab monitoring system can be configured for determining grab height data from the sensed air pressure and air temperature.

[0048] Optionally, the grab data measurement unit further comprises a distance measurement sensor attachable at or near one of at least two movable parts of the grab. The distance measurement sensor can be configured for measuring the distance between a surface of material inside the grab and the distance measurement sensor when the at least two movable parts of the grab are closed. The distance measurement sensor can e.g. comprise a camera, laser, radar or LiDAR. The processor or the grab monitoring system can be configured for determining from the detected distance between the material and the sensor, the amount of material inside the grab. The determined amount of material inside the grab can be used by the grab monitoring system and / or the processor in determining data indicative of grab usage. If a change in the amount of material inside the grab over time is determined, this can be an indication that a loading and / or unloading capacity of the grab has been decreasing over time and the grab might require maintenance. Characteristics of the material, such as density and / or specific volume, can be provided to the grab data measurement unit and / or grab monitoring system by means of a user input. This ensures that the material characteristics can be used in determining data indicative of grab usage. The grab data measurement unit can further comprise at least one load shackle, load cell and / or strain gauge attachable at or near one of at least two movable parts of the grab. The amount of material inside the grab can be determined using the at least one load shackle, load cell and / or strain gauge. The at least one load shackle, load cell and / or strain gauge can be configured for measuring the amount of material inside the grab when the at least two movable parts of the grab are closed. Optionally, the grab data measurement unit further comprises an accelerometer configured for measuring grab acceleration data of the grab over time. The processor or the grab monitoring system can be configured for detecting, from the measured grab acceleration data, a collision between the grab and at least one of a ship, crane, quay, shore or bulk material. The processor or the grab monitoring system can be configured for detecting, from the measured grab acceleration data, an angle at which the grab lands on het material.

[0049] Optionally, the grab data collection system further comprises a GPS sensor configured for measuring location data of the grab over time.

[0050] Optionally, the grab data measurement unit is housed with a protective layer around the outer surface of the grab data measurement unit excluding an outer surface part at or near the atmospheric pressure sensor.

[0051] Optionally, the grab data measurement unit comprises a watertight membrane at the outer surface part at or near the atmospheric pressure sensor, for allowing the atmospheric pressure sensor to sense air pressure.

[0052] Optionally, the grab data measurement unit comprises a battery, and / or an external power source is connectable to the grab data measurement unit. The battery and / or external power source can be configured for powering the other components of the grab data measurement unit. Elaborating on the above mentioned further aspects of the invention, a grab data measurement unit may be provided as comprised in the grab data collection system as described.

[0053] Elaborating on the above mentioned further aspects of the invention, a grab monitoring system may be provided as comprised in the grab data collection system as described. The grab monitoring system can be arranged to monitor the sensed ambient air pressure over time so as to detect changes in sensed air pressure that are indicative of hoist of the grab. The grab monitoring system can be configured for determining data indicative of grab usage from the determined grab height data.

[0054] Elaborating on the above mentioned further aspects of the invention, a use of an atmospheric pressure sensor on a mechanical grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab may be provided. The atmospheric pressure sensor may preferably be provided on a mechanical grab of a grab data collection system as described.

[0055] Elaborating on the above mentioned further aspects of the invention, a mechanical grab provided with a grab data measurement unit attached thereto may be provided. The grab data measurement unit may include an atmospheric pressure sensor attached to the grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab. The mechanical grab may preferably comprise a mechanical grab for a grab data collection system as described.

[0056] Elaborating on the above mentioned further aspects of the invention, a grab data measurement unit attachable to a mechanical grab may be provided. The grab data measurement unit may include an atmospheric pressure sensor to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab. The mechanical grab may preferably comprise a mechanical grab for a grab data collection system as described. It will be appreciated that any of the aspects, features and options described in view of the method for providing data indicative of grab usage of a mechanical grab apply equally to the grab data collection system for providing data indicative of grab usage of a mechanical grab, the grab data measurement unit, the grab monitoring system, the use of an atmospheric pressure sensor on a mechanical grab to sense ambient air pressure at the grab, the mechanical grab provided with a grab data measurement unit attached thereto, the grab data measurement unit attachable to a mechanical grab, and vice versa. It will also be clear that any one or more of the above aspects, features and options can be combined.

[0057] Brief description of the drawings

[0058] Embodiments of the present invention will now be described in detail with reference to the accompanying drawings in which:

[0059] Figures 1A and IB show illustrations of schematic representations of examples of a grab data collection system;

[0060] Figures 2A and 2B show illustrations of schematic representations of examples of a grab data collection system;

[0061] Figures 3A and 3B show illustrations of schematic representations of examples of a grab data collection system;

[0062] Figure 4 shows an illustration of a schematic representation of an example of the grab data collection system; and

[0063] Figure 5 shows an exemplary flow chart of a method for providing data indicative of grab usage of a mechanical grab.

[0064] Detailed description

[0065] Figures 1A and IB show illustrations of schematic representations of examples of a grab data collection system 1 configured for providing data indicative of grab usage of a mechanical grab 2. In Figures 1A and IB a side view of the system 1 is shown. The grab data collection system 1 comprises a grab data measurement unit 4 and a grab monitoring system 6. The grab data measurement unit 4 is in the example of Figure 1A attached to the mechanical grab 2. The grab data measurement unit 4 can also be detached from the mechanical grab 2, such as after manufacturing thereof and prior to attachment to the grab 2, as shown in Figure IB. The grab data measurement unit 4 comprises an atmospheric pressure sensor 8. In this example, the grab data measurement unit 4 also comprises a processor 10 and a first communication unit 12. It will be appreciated that the grab data measurement unit 4 can comprise only the atmospheric pressure sensor 8 instead. The atmospheric pressure sensor 8 is configured for sensing air pressure at the mechanical grab 2 over time. It will be appreciated that a single atmospheric pressure sensor 8 in the grab data measurement unit 4 can be sufficient to sense air pressure at the mechanical grab 2 over time. The atmospheric pressure sensor 8 can comprise an analog or digital atmospheric pressure sensor, such as a barometer.

[0066] A pressure sensitive part of the atmospheric pressure sensor 8 can be positioned in various measurement orientations, e.g. perpendicular or parallel to the hoisting direction of the grab 2. Such a pressure sensitive part of the atmospheric pressure sensor 8 can e.g. comprise a pressure sensitive membrane or other type of pressure sensitive element that extends, in rest, into a planar surface. If the pressure sensitive part of the atmospheric pressure sensor 8 is positioned perpendicular to the hoisting direction of the grab 2, the results of ambient air pressure sensing could be affected by the force and / or motion of the grab 2 during at least partially vertical displacement of the mechanical grab 2. By positioning the pressure sensitive part of the atmospheric pressure sensor 8 parallel to the hoisting direction of the grab 2, influence of the force and / or motion of the grab 2 during vertical displacement thereof on the sensing of ambient air pressure could be prevented or at least diminished. Movement, such as bulging, of the pressure sensitive part of the atmospheric pressure sensor 8 can be used to control activation of other components of the grab data measurement unit 4 and of the grab monitoring system 6, and / or to detect collisions and / or impacts.

[0067] The grab monitoring system 6 is configured for monitoring the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab 2. The processor 10 is in this example configured for determining grab height data from the sensed air pressure. The grab monitoring system 6 comprises in this example a second communication unit 7. Here, the first communication unit 12 is configured for transferring data indicative of grab usage to the second communication unit 7 of the grab monitoring system 6, as indicated by the dashed line. The first communication unit 12 can comprise a transmitter and / or a transceiver. The second communication unit 7 can comprise a receiver and / or a transceiver. A transmitter is configured for transmitting data, and a receiver is configured for receiving data. A transceiver is configured for transmitting data as well as for receiving data. The data indicative of grab usage can be transferred by the first communication unit 12 to the second communication unit 7 wirelessly. The data indicative of grab usage in this example comprises and / or is determined from the determined grab height data. In this example, the data indicative of grab usage comprises data indicative of a change in height of the grab 2. In case the data indicative of grab usage comprises data indicative of a change in height of the grab 2, a sensed change in air pressure can be indicative of hoist. The grab monitoring system 6 is in this example configured for determining data indicative of grab usage from the determined grab height data. The grab monitoring system 6 can be provided remote from the grab 2, such as at the quay 22, at a crane, on shore or in a workplace or office. The first communication unit 12 can comprise a transceiver that is configured for receiving data from the grab monitoring system 6, such as for providing an over-the-air firmware update. In this example, the grab data measurement unit 4 further comprises a battery 14. The battery 14 is configured for powering the other components of the grab data measurement unit 4, i.e. for powering the atmospheric pressure sensor 8, the processor 10 and the first communication unit 12. Here, the battery 14 is configured for directly supplying power to the processor 8. The battery 14 in this example comprises a capacity of at least 10 Ah, and has in this example a capacity of approximately 50 Ah. The components of the grab data measurement unit 4 can alternatively or additionally be powered by an external power source. The electrical energy required for powering the atmospheric pressure sensor 8 of the grab data measurement unit 4 is preferably less than 100 pAh, more preferably less than 10 pAh. In this example, the electrical energy required for powering the atmospheric pressure sensor 8 of the grab data measurement unit 4 is approximately 1.7 pAh.

[0068] The grab data measurement unit 4 can further measure an energy level of the remaining energy that is left in the battery 14. If the measured energy level drops below a predetermined reference energy level, this can be communicated by the grab data measurement unit 4 to a user by means of an auditive, visual and / or electronical signal. The grab data measurement unit 4 can further comprise one or more Light Emitting Diodes, LEDs. The one or more LEDs can be configured to emit fight upon detecting that one or more of the data indicative of grab usage, the grab height data and / or sensed air pressure exceeds a predetermined threshold value. The emission of light by the one or more LEDs can be indicative of the remaining energy level that is left in the battery 14. The one or more LEDs can be controlled by the processor 10 and / or the grab monitoring system 6.

[0069] Figures 2A and 2B show illustrations of schematic representations of examples of a grab data collection system 1 configured for providing data indicative of grab usage of a mechanical grab 2. In Figures 2A and 2B a side view of the system 1 is shown. The grab data collection system 1 comprises the grab data measurement unit 4 and the grab monitoring system 6. The grab data measurement unit 4 is in the example of Figure 2A attached to the mechanical grab 2. In Figure 2B, the grab data measurement unit 4 is detached from the mechanical grab 2. The grab data measurement unit 4 comprises the atmospheric pressure sensor 8. The grab monitoring system 6 is configured for monitoring the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab 2.

[0070] In the system 1 of Figure 2B, the grab data measurement unit 4 comprises a first data communication port 11A, and the grab monitoring system 6 comprises a second data communication port 11B. Here, the first data communication port 11A is configured for receiving sensed air pressure data from the atmospheric pressure sensor 8, and for communicating said data to the second data communication port 11B. In this example, the sensed air pressure data can be communicated between the first data communication port 11A and the second data communication port 11B by means of a portable storage medium 13. The portable storage medium 13, such as an USB flash drive or RFID communication unit, is in this example configured to be connected to or in close proximity of one of the first and second data communication ports 11A,11B for allowing data communication between the portable storage medium 13 and the respective one of the communication ports 11A,11B. Using the portable storage medium 13, a user can transfer the sensed air pressure data from the first data communication port 11A to the second data communication port 11B. Said data transfer can be performed by a user at predetermined time instances, e.g. monthly, weekly or daily, for allowing the grab monitoring system 6 to perform the monitoring of sensed ambient air pressure over time.

[0071] Figures 3A and 3B show illustrations of schematic representations of examples of the grab data collection system 1. The mechanical grab 2 is configured for transferring product 16, such as bulk, from a ship 18 to a hopper 20 on a quay 22. In Figure 3A, the mechanical grab 2 is at a first position close to the ship 18 for collecting some product 16 in the grab 2. The grab 2 can be moved to a second position at the hopper 20 for unloading the collected product 16 therein. The mechanical grab 2 is close to the hopper 20 at the second position in Figure 3B for unloading the product 16 from the grab 2.

[0072] When the grab 2 is in the first position, the atmospheric pressure sensor 8 senses a first air pressure at the grab 2. The processor 10 determines a first grab height Hl from the sensed first air pressure. The first grab height Hl corresponds to the first position of the grab 2 in Figure 3A. After the grab 2 has moved to the second position, the atmospheric pressure sensor 8 senses a second air pressure at the grab 2. A second grab height H2 is determined from the sensed second air pressure by the processor 10. The second grab height H2 is the height of the grab 2 in the second position, as shown in Figure 3B. The second grab height H2 is in this example measured at a later moment in time than the first grab height Hl. The data indicative of grab usage in this example comprises first and second grab height data H1,H2. The first and second grab height H1,H2 are together indicative of a change in height h of the grab 2. A change in height h can be determined by comparing the first sensed air pressure, corresponding to the first grab height Hl, to the second sensed air pressure, corresponding to the second grab height H2. The second sensed air pressure is separated from the first sensed air pressure by a predetermined time period. The predetermined time period can comprise a couple of minutes, e.g. 10, 5, 3 or 1 minutes, and preferably seconds, e.g. 30, 15 or 10 seconds, or a second. The second sensed air pressure is in this example sensed by the atmospheric pressure sensor 8 after the first sensed air pressure. An air pressure difference between the first sensed air pressure and the second sensed air pressure can be used to determine the change in height h of the grab 2. The first communication unit 12 is in this example configured for transferring the determined grab height data, and / or sensed air pressure, to the second communication unit 7. Here, the grab monitoring system 6 is configured for determining the occurrence of at least a predetermined change in height h of the grab 2. It will be appreciated that the processor 10 can be configured for determining the occurrence of at least a predetermined change in height h instead. If the occurrence of at least a predetermined change in height h is determined, the accompanying sensed change in air pressure is indicative of hoist. The grab monitoring system 6 is in this example configured for determining data indicative of movement cycles of the grab 2 based on the occurrence of at least a predetermined change in height h. The predetermined change in height h can comprise a positive or negative height difference the grab 2 at least requires to move during one movement cycle. The predetermined time period between the first and second sensed air pressures can be shorter than or equal to the minimum time period the grab 2 requires for completing one movement cycle. The grab monitoring system 6 can be configured for determining the occurrence of at least a predetermined gradient G of change in height over time. The sensed change in air pressure, e.g. due to a change in height h of the grab 2, can be indicative of hoist when changes in ambient air pressure exceed the predetermined gradient G of change in height over time. The predetermined gradient G can e.g. comprise an absolute gradient G of change in height over time of at least 12, 1.2 or 0.12 Pascal per T1 seconds. In said absolute gradient G, T1 indicates a time period of e.g. 10, 5, 3, or 1 seconds between ambient air pressure measurements measured by the atmospheric pressure sensor at the grab. Herein, a change in air pressure of 12 Pascal per T1 seconds can be indicative of a change in height h of the grab 2 in the order of approximately one or more meters. A measured air pressure change of 0.12 Pascal can be indicative of a change in height h of the grab 2 in the order of approximately one or more centimeters. The atmospheric pressure sensor 8 therefore requires a measurement accuracy of at least 12 Pascal per T1 seconds, preferably 1.2 Pascal per T1 seconds, and more preferably 0.12 Pascal per T1 seconds.

[0073] Figure 4 shows an illustration of a schematic representation of an example of the grab data collection system 1. In this example, the grab data measurement unit 4 further comprises a temperature sensor 24, a distance measurement sensor 26, an accelerometer 28, a memory 29 and a GPS sensor 30. The temperature sensor 24, a distance measurement sensor 26, and an accelerometer 28 are attached or attachable to the grab 2. Here, the temperature sensor 24 is integral with the atmospheric pressure sensor 8. The temperature sensor 24 is configured for measuring air temperature at the mechanical grab 2 over time. The air temperature measured by the temperature sensor 24 is used to compensate for temperature changes in the sensed air pressure, in order to more accurately determine grab height data. Here, the processor 10 is configured for determining grab height data from the measured air pressure and air temperature. It will be appreciated that the grab monitoring system 6 can be configured for compensating for temperature changes in the sensed air pressure for determining grab height data instead.

[0074] In this example, the components of the grab data measurement unit 4 are housed in a housing 32. The distance measurement sensor 26 and the accelerometer 28 are in this example positioned in the housing 32. The distance measurement sensor 26 is attachable at or near one of at least two movable parts of the grab 2. The distance measurement sensor 26 is configured for measuring the distance between a surface of material, e.g. of product 16, inside the grab 2 and the distance measurement sensor 26 when the at least two movable parts of the grab 2 are closed. The grab monitoring system 6 is in this example configured for determining from the detected distance between the material and the sensor 26, the amount of material inside the grab 2. It will be appreciated that the processor 10 can be configured for determining the amount of material inside the grab 2 from the detected distance between the material and the sensor 26 instead. The accelerometer 28 is configured for measuring grab acceleration data of the grab 2 over time. The grab monitoring system 6 is in this example configured for detecting, from the measured grab acceleration data, a collision between the grab 2 and at least one of a ship, quay, crane or bulk material. It will be appreciated that the processor 10 can be configured for detecting such collision of the grab 2 instead. The grab monitoring system 6 is in this example configured for detecting, from the measured grab acceleration data, an angle at which the grab 2 lands on het material. The angle between the grab 2 and the material can be used in determining data indicative of grab usage. The memory 29 is in this example configured for storing the determined grab height data, the sensed air pressure and / or data indicative of grab usage therein prior to transferring said data to the grab monitoring system 6.

[0075] The GPS sensor 30 is configured for measuring location data of the grab 2 over time. The housing 32 of the grab data measurement unit 4 is in this example provided with a protective layer 34 around the outer surface of the grab data measurement unit 4 excluding an outer surface part at or near the atmospheric pressure sensor 8. The protective layer 34 can be formed of resin or other type of material with relatively high vibration and / or impact damping ability. The protective layer 34 is configured to prevent product 16 and / or dust and / or water from entering the housing 32 of the grab data measurement unit 4. The grab data measurement unit 4 in this example comprises a watertight membrane 36 at the outer surface part at or near the atmospheric pressure sensor 8. The watertight membrane 36 is in this example flexible. The watertight membrane 36 is configured for being bend as a result of a change in atmospheric pressure, thereby allowing the atmospheric pressure sensor 8 to sense air pressure by the degree of bulging of the membrane 36. The membrane 36 is not covered by the protective layer 34, in order to allow for air to flow along the membrane 36 for measuring the air pressure with the atmospheric pressure sensor 8. Alternatively or additionally, the watertight membrane 36 can be gas permeable. The term ‘gas permeable’ should in the context of the gas permeable and watertight membrane 36 be interpreted as the membrane 36 having at least one hole or other type of passage through which the atmospheric pressure sensor 8 can measure air pressure. The grab monitoring system 6 is in this example configured for storing the determined grab height data, the sensed air pressure and / or data indicative of grab usage in a database in the cloud 38. Alternatively or additionally, the determined grab height data, the sensed air pressure and / or data indicative of grab usage can be transferred to the grab monitoring system 6 via the cloud 38.

[0076] Figure 5 shows an exemplary flow chart of a method 100 for providing data indicative of grab usage of the mechanical grab 2. The method 100 can e.g. be performed using a grab data measurement unit 4 and a grab monitoring system 6 as described in view of any of Figures 1-4. When performing the method 100, the grab data measurement unit 4 is in this example attached to the mechanical grab 2. Optional steps are shown in dashed boxes. In a first step 102, air pressure at the mechanical grab 2 is sensed in this example using the atmospheric pressure sensor 8. Air temperature is in this example measured at the mechanical grab over time using the temperature sensor 24 in step 104. In this example, the distance between material, e.g. product 16, inside the grab 2 and the distance measurement sensor 26 is measured using the distance measurement sensor 26 attached at or near one of at least two movable parts of the grab 2, when the at least two movable parts of the grab 2 are closed in step 106. In step 108, grab acceleration data of the grab 2 is in this example measured over time using the accelerometer 28. In this example, location data of the grab 2 is measured over time using a GPS sensor 30 in step 110. Part acceleration data of one of the at least two movable parts of the grab 2 can be measured over time, using the accelerometer 28, in step 112. The accelerometer 28 is attached to one of at least two movable parts of the grab 2 in step 112. The part acceleration data is used in optional step 138.

[0077] In step 114, grab height data is in this example determined from the measured air pressure using the processor 10 or the grab monitoring system 6. The step 114 in this example comprises determining grab height data from the measured air pressure and air temperature using the grab monitoring system 6. In this example, the amount of material inside the grab 2 is determined in step 116, using the grab monitoring system 6, from the measured distance between a surface of the material and the sensor 26. The occurrence of at least a predetermined change in height is in this example determined using the grab monitoring system 6 in step 118. It will be appreciated that the occurrence of said at least a predetermined change in height can be determined in step 118 using the processor 10 instead. In step 120, the occurrence of grab movement is in this example detected from the grab height data using the processor 10. Here, it is determined, using the processor 10 or the grab monitoring system 6, that an event occurs when a predetermined change in height within a predetermined time interval exceeds a predetermined first threshold, a collision occurs, or a closing and / or opening occurs in step 122. In step 124, the first communication unit 12 is in this example controlled, using the processor 10 or the grab monitoring system 6, for transferring more data per unit time in respect of the event, than in respect of periods of time not associated with an event. Alternatively or additionally, movement of the pressure sensitive part of the atmospheric pressure sensor 8 can be used to control activation of other components of the grab data measurement unit 4 and of the grab monitoring system 6.

[0078] The determined grab height data and / or measured air pressure can be processed in step 126. In step 128, data indicative of grab usage is in this example transferred to the second communication unit 7 using the first communication unit 12. The data indicative of grab usage of step 128 comprises and / or is in this example determined from the determined grab height data. In this example, the data indicative of grab usage comprises data indicative of a change in height of the grab. The step 128 in this example comprises transferring the determined grab height data, and / or measured air pressure, to the grab monitoring system 6. Step 128 can be performed after step 126. The step 128 can comprise transferring the processed grab height data and / or air pressure from step 126 to the grab monitoring system 6. The grab monitoring system 6 can be provided remote from the grab 6, such as at the quay 22, at a crane, on shore or in a workplace or office. The step 128 can further comprise storing the determined grab height data, the measured air pressure and / or data indicative of grab usage in a database in the cloud. The step 128 can be performed after a predetermined time period and / or after at least a predetermined change in height is determined. In step 130, further data indicative of grab usage is determined in this example. The step 130 is performed after step 128. The further data indicative of grab usage of step 130 in this example comprises data indicative of movement cycles of the grab 2. In this example, the step 130 comprises detecting, using the grab monitoring system 6, an amount of movement cycles of the grab 2 over time. It will be appreciated that the data indicative of movement cycles of the grab can comprise determined changes in grab height, and / or changes in sensed air pressure, that are indicative of hoist of the grab. The detected amount of movement cycles of the grab movement can be reset, using the processor 10 or the grab monitoring system 6, in response to a user input in step 132.

[0079] In step 134, a collision between the grab 2 and at least one of a ship, crane, quay or bulk material is in this example detected from the measured grab acceleration data, using the grab monitoring system 6. Using the processor 10, activating and / or inactivating of the GPS sensor 30 and / or the first communication unit 12 is in this example controlled over time based on the grab movement in step 136. Alternatively or additionally, movement of the pressure sensitive part of the atmospheric pressure sensor 8 can be used to control activation of other components of the grab data measurement unit 4 and of the grab monitoring system 6, and / or to detect collisions and / or impacts. The step 136 can further comprise inactivating, using the processor 10, when for at least a predetermined time period the occurrence of grab movement is absent, after measuring the location data, the GPS sensor 30 and / or the first communication unit 12. The step 136 can further comprise activating, using the processor 10, when for at least a predetermined time period the occurrence of grab movement is detected, the GPS sensor 30 and / or the first communication unit 12. In step 138, a closing and / or opening of the one movable part of the grab 2 with respect to the other can be detected from the measured part acceleration data using the processor 10. After detecting the closing and / or opening of the one movable part of the grab 2 with respect to the other in step 138, a lubricant can be provided to a rotatable part of the grab 2 using a pump and / or valve during the closing and / or opening in step 140. The step 140 can be performed after the detected amount of movement cycles of the grab movement exceeds a predetermined second threshold.

[0080] Herein, the invention is described with reference to specific examples of embodiments of the invention. It will, however, be evident that various modifications and changes may be made therein, without departing from the essence of the invention. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, alternative embodiments having combinations of all or some of the features described in these separate embodiments are also envisaged. However, other modifications, variations, and alternatives are also possible. The specifications, drawings and examples are, accordingly, to be regarded in an illustrative sense rather than in a restrictive sense.

[0081] For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

[0082] In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word ‘comprising’ does not exclude the presence of other features or steps than those listed in a claim.

[0083] Furthermore, the words ‘a’ and ‘an’ shall not be construed as limited to ‘only one’, but instead are used to mean ‘at least one’, and do not exclude a plurality. The mere fact that certain measures are recited in mutually different claims does not indicate that a combination of these measures cannot be used to an advantage.

Claims

Claims1. A method for providing data indicative of grab usage of a mechanical grab, comprising:- sensing ambient air pressure at the mechanical grab; and- monitoring the sensed ambient air pressure over time so as to detect changes in air pressure that are indicative of hoist of the grab.

2. The method according to claim 1, wherein the method is performed using a grab data measurement unit and a grab monitoring system, the grab data measurement unit comprising an atmospheric pressure sensor, wherein the grab data measurement unit is attached to the mechanical grab, and wherein the sensing is performed using the atmospheric pressure sensor and the monitoring is performed using the grab monitoring system.

3. The method according to claim 2, wherein the grab data measurement unit comprises a processor, and wherein the method further comprises determining, using the processor or the grab monitoring system, grab height data from the sensed air pressure.

4. The method according to claim 3, wherein the grab data measurement unit comprises a first communication unit and the grab monitoring system comprises a second communication unit, wherein the method comprises transferring, using the first communication unit, data indicative of grab usage to the second communication unit, wherein optionally data indicative of grab usage comprises and / or is determined from the determined grab height data.

5. The method according to claim 4, wherein the data indicative of grab usage comprises data indicative of a change in height of the grab.

6. The method according to claim 4 or 5, further comprising a step of determining, using the processor or the grab monitoring system, the occurrence of at least a predetermined change in height.

7. The method according to claim 4, 5 or 6, wherein the step of transferring comprises transferring the determined grab height data, and / or sensed air pressure, to the second communication unit.

8. The method according to any of claims 4-7, further comprising determining, after the step of transferring, further data indicative of grab usage, and wherein the further data indicative of grab usage comprises data indicative of movement cycles of the grab.

9. The method according to claim 8, wherein the step of determining further data indicative of grab usage comprises detecting, using the processor or the grab monitoring system, an amount of movement cycles of the grab over time.

10. The method according to any of claims 4-9, further comprising a step of measuring, using a temperature sensor attached to the grab, air temperature at the mechanical grab over time, and wherein the step of determining grab height data comprises determining, from the measured air pressure and air temperature, using the processor or the grab monitoring system, grab height data.

11. The method according to any of claims 4-10, further comprising:- measuring, using at least one distance measurement sensor each being attached at or near a respective one of at least two movable parts of the grab, the distance between a surface of material inside the grab and the distance measurement sensor when the at least two movable parts of the grab are closed; and optionally- determining, using the processor or the grab monitoring system, from the measured distance between the material and the sensor, the amount of material inside the grab.

12. The method according to any of claims 4-11, further comprising measuring, using at least one load shackle, load cell and / or strain gaugeattached at or near one of at least two movable parts of the grab, the amount of material inside the grab when the at least two movable parts of the grab are closed.

13. The method according to any of claims 4-12, wherein the grab data measurement unit comprises an accelerometer, the method comprising:- measuring, using the accelerometer, grab acceleration data of the grab over time;- detecting, from the measured grab acceleration data, using the processor or the grab monitoring system, a collision between the grab and at least one of a ship, crane, quay or bulk material; and optionally- detecting, from the measured grab acceleration data, using the processor or the grab monitoring system, an angle at which the grab lands on the material.

14. The method according to any of claims 4-13, further comprising a step of measuring, using a GPS sensor, location data of the grab over time.

15. The method according to any of claims 4-14, further comprising:- detecting, from the grab height data, using the processor, the occurrence of grab movement; and- controlling, using the processor, activating and / or inactivating of the GPS sensor and / or the first communication unit over time based on the grab movement.

16. The method according to claim 15, wherein the step of controlling further comprises at least one of:- inactivating, using the processor, when for at least a predetermined time period the occurrence of grab movement is absent, after measuring the location data, the GPS sensor and / or the first communication unit; and- activating, using the processor, when for at least a predetermined time period the occurrence of grab movement is detected, the GPS sensor and / or the first communication unit.

17. The method according to any of claims 4-16, wherein the grab monitoring system is provided remote from the grab, such as at the quay, at a crane, on shore or in a workplace or office.

18. The method according to any of claims 4-17, wherein the step of transferring further comprises storing the determined grab height data, the sensed air pressure and / or data indicative of grab usage in a database in the cloud.

19. The method according to any of claims 4-18, wherein the step of transferring is performed after a predetermined time period and / or after at least a predetermined change in height is determined.

20. The method according to claim 7, wherein the method comprises a step of processing, prior to the transferring, the determined grab height data and / or sensed air pressure, and wherein the transferring comprises transferring said processed grab height data and / or air pressure to the second communication unit.

21. The method according to any of claims 4-20, comprising determining, using the processor or the grab monitoring system, that an event occurs when a predetermined change in height within a predetermined time interval exceeds a predetermined first threshold, a collision occurs, or a closing and / or opening occurs, and comprising controlling, using the processor or the grab monitoring system, the first communication unit for transferring more data per unit time in respect of the event, than in respect of periods of time not associated with an event.

22. The method according to any of claims 4-21, when at least dependent on claim 9, the method further comprising resetting, using the processor or the grab monitoring system, the detected amount of movement cycles of the grab movement, in response to a user input.

23. The method according to any of claims 4-22, when at least dependent on claim 13, wherein the accelerometer is attached to one of at least two movable parts of the grab, the method comprising:- measuring, using the accelerometer, part acceleration data of said one of the at least two movable parts of the grab over time;- detecting, from the measured part acceleration data, using the processor, a closing and / or opening of the one movable part of the grab with respect to the other; and- providing, after detecting the closing and / or opening of the one movable part of the grab with respect to the other, a lubricant to a rotatable part of the grab using a pump and / or a valve during and / or after the closing and / or opening.

24. The method according to claim 23, when at least dependent on claim 9, wherein the step of providing the lubricant is performed after the detected amount of movement cycles of the grab movement exceeds a predetermined second threshold.

25. The method according to any of claims 2-24, wherein the grab data measurement unit comprises a battery, and / or an external power source is connectable to the grab data measurement unit, the method comprises powering, using the battery and / or the external power source, the other components of the grab data measurement unit.

26. A grab data collection system configured for providing data indicative of grab usage of a mechanical grab, wherein the grab data collection system comprises a grab data measurement unit and a grab monitoring system, wherein the grab data measurement unit is attached or attachable to the mechanical grab, the grab data measurement unit comprising an atmospheric pressure sensor configured for sensing ambient air pressure at the mechanical grab, and the grab monitoring system being arranged to monitor the sensed ambient air pressure over time so as to detect changes in sensed air pressure that are indicative of hoist of the grab.

27. The grab data collection system according to claim 26, wherein the grab data measurement unit comprises a processor, wherein the processor or the grab monitoring system is configured for determining grab height data from the sensed air pressure.

28. The grab data collection system according to claim 27, wherein the grab data measurement unit comprises a first communication unit and the grab monitoring system comprises a second communication unit, wherein the first communication unit is configured for transferring data indicative of grab usage to the second communication unit, wherein optionally data indicative of grab usage comprises and / or is determined from the determined grab height data.

29. The grab data collection system according to claim 28, wherein the data indicative of grab usage comprises data indicative of a change in height of the grab.

30. The grab data collection system according to claim 28 or 29, wherein the processor or the grab monitoring system is configured for determining the occurrence of at least a predetermined change in height.

31. The grab data collection system according to claim 28, 29 or 30, wherein the transferring comprises transferring the determined grab height data, and / or sensed air pressure, to the second communication unit.

32. The grab data collection system according to any of claims 28-31, wherein the data indicative of grab usage comprises data indicative of movement cycles of the grab.

33. The grab data collection system according to any of claims 28-32, wherein the grab data measurement unit further comprises a temperature sensor attached or attachable to the grab, wherein the temperature sensor is configured for measuring air temperature at the mechanical grab over time, and wherein the processor or the grab monitoring system is configured for determining grab height data from the measured air pressure and air temperature.

34. The grab data collection system according to any of claims 28-33, wherein the grab data measurement unit further comprises a distance measurement sensor attachable at or near one of at least two movable parts of the grab, wherein the distance measurement sensor is configured for measuring the distance between a surface of material inside the grab andthe distance measurement sensor when the at least two movable parts of the grab are closed, and wherein the processor or the grab monitoring system is configured for determining from the detected distance between the material and the sensor, the amount of material inside the grab.

35. The grab data collection system according to any of claims 28-34, wherein the grab data measurement unit further comprises at least one load shackle, load cell and / or strain gauge attachable at or near one of at least two movable parts of the grab, wherein the at least one load shackle, load cell and / or strain gauge is configured for measuring the amount of material inside the grab when the at least two movable parts of the grab are closed.

36. The grab data collection system according to any of claims 28-35, wherein the grab data measurement unit further comprises an accelerometer configured for measuring grab acceleration data of the grab over time, and wherein the processor or the grab monitoring system is configured for detecting, from the measured grab acceleration data, a collision between the grab and at least one of a ship, quay, crane or bulk material, and optionally the processor or the grab monitoring system is configured for detecting, from the measured grab acceleration data, an angle at which the grab lands on the material.

37. The grab data collection system according to any of claims 28-36, comprising a GPS sensor configured for measuring location data of the grab over time.

38. The grab data collection system according to any of claims 28-37, wherein the grab data measurement unit is housed with a protective layer around the outer surface of the grab data measurement unit excluding an outer surface part at or near the atmospheric pressure sensor.

39. The grab data collection system according to claim 38, wherein the grab data measurement unit comprises a watertight membrane at the outer surface part at or near the atmospheric pressure sensor, for allowing the atmospheric pressure sensor to sense air pressure.

40. The grab data collection system according to any of claims 26-39, wherein the grab data measurement unit comprises a battery, and / or an external power source is connectable to the grab data measurement unit, wherein the battery and / or external power source is configured for powering the other components of the grab data measurement unit.

41. A grab data measurement unit as comprised in the grab data collection system according to any of claims 26-40.

42. A grab monitoring system as comprised in the grab data collection system according to any of claims 26-40, wherein the grab monitoring system is configured for determining data indicative of grab usage from the determined grab height data.

43. Use of an atmospheric pressure sensor on a mechanical grab, preferably on a mechanical grab of a grab data collection system according to any of claims 26-40, to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab.

44. A mechanical grab, preferably a mechanical grab for a grab data collection system according to any of claims 26-40, provided with a grab data measurement unit attached thereto, the grab data measurement unit including an atmospheric pressure sensor attached to the grab to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab.

45. A grab data measurement unit attachable to a mechanical grab, preferably a mechanical grab for a grab data collection system according to any of claims 26-40, the grab data measurement unit including an atmospheric pressure sensor to sense ambient air pressure at the grab, so as to detect changes in air pressure that are indicative of hoist of the grab.

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