FI128510B - Method and apparatus for detecting movements of cargo while a vessel is en route - Google Patents

Abstract

An apparatus for detecting movements of cargo (104) on board a vessel (101, 1001) comprises a LIDAR (201) configured to generate measurement data. A conveyor (202) is configured to convey said LIDAR (201) within a cargo space (102, 103) of said vessel (101, 1001) while said vessel is en route. A data collector (805) is configured to collect sets of said measurement data.

Description

METHOD AND APPARATUS FOR DETECTING MOVEMENTS OF CARGO WHILE A VESSEL IS EN ROUTE

FIELD OF THE INVENTION The invention is related to the task of moni- toring the operation of a vessel such as a ship or ferry. In particular the invention is related to auto- matically detecting possible movements of cargo of a sea-going vessel while the vessel is en route.

BACKGROUND OF THE INVENTION The balance of a sea-going vessel, such as a ship, is heavily influenced by the mass of cargo items and/or bulk cargo that it transports. Spontaneous movements of cargo may be caused by high seas during transport. They are undesirable, because they may cause imbalance and even catastrophic consequences like serious structural damage or capsizing. Known measures to be taken to mitigate threats of this kind include carefully planned loading, load securing and bracing, proactive route planning, and reactive chang- es in routing to avoid or evade hazardous conditions en route.

SUMMARY 2 Q This summary is provided to introduce a se- + lection of concepts in a simplified form that are fur- = ther described below in the detailed description. This A 30 summary is not intended to identify key features or z essential features of the claimed subject matter, nor LO is it intended to be used to limit the scope of the 3 claimed subject matter. = It is an objective to present a method and an N 35 arrangement for providing a timely warning of move- ments of cargo on board a vessel. A further objectiveis that the method and arrangement of said kind would be particularly suited for operation on unmanned ves- sels. A yet further objective is that the same method and arrangement would be applicable in different kinds of vessels and different kinds of cargoes.

These and other objectives are achieved with a method and an arrangement as described in the re- spective independent claims. Further objectives and advantages are achieved by the embodiments described in the depending claims.

According to an aspect, an apparatus is pro- vided for detecting movements of cargo on board a ves- sel. The apparatus comprises a LIDAR configured to generate measurement data, a conveyor configured to convey said LIDAR within a cargo space of said vessel while said vessel is en route, and a data collector configured to collect sets of said measurement data.

According to another aspect, a vessel is pro- vided. The vessel comprises at least one apparatus of the kind described above.

According to yet another aspect, a method is provided for detecting movements of cargo on board a vessel. The method comprises using a LIDAR to generate two sets of measurement data representing a topography of cargo within a same region of a cargo space of said vessel while said vessel is en route.

Many of the attendant features will be more = readily appreciated as they become better understood N by reference to the following detailed description S 30 considered in connection with the accompanying draw- 2 ings.

i © BRIEF DESCRIPTION OF THE DRAWINGS 3 The accompanying drawings, which are included = 35 to provide a further understanding of the invention N and constitute a part of this specification, illus- trate embodiments of the invention and together withthe description help to explain the principles of the invention. In the drawings: Figure 1 illustrates a vessel with two cargo spaces, Figure 2 illustrates a LIDAR and a conveyor in a cargo space of a vessel, Figure 3 illustrates an example of a convey- or, Figure 4 illustrates another example of a conveyor, Figure 5 illustrates another example of a conveyor, Figure 6 illustrates another example of a conveyor, Figure 7 illustrates another example of a conveyor, Figure 8 illustrates an apparatus with a LI- DAR together with processing and control systems, Figure 9 illustrates a part of a control sys- tem of a vessel, Figure 10 illustrates a vessel and a remote onshore control centre, and Figure 11 illustrates a method.

DETAILED DESCRIPTION Fig. 1 illustrates a vessel 101 that compris- © es two cargo spaces 102 and 103. In this exemplary D case the vessel 101 may be for example a PCTC (Pure 5 Car/Truck Carrier), the cargo of which consists of = 30 road vehicles such as semi-trailer trucks 104. Cargo TY spaces optimized for the transport of road vehicles E are often called decks, in contrast to other kinds of LO cargo spaces like cargo holds used for packaged or 3 bulk cargo. For the present invention the detailed = 35 structure and arrangement of cargo spaces is not im- N portant, so the more general designation cargo space can be used. For the purposes of this description acargo space is a dedicated space within a vessel, in which cargo is to be transported and in which sponta- neous movements of cargo are not desirable while the vessel is en route.

Fig. 2 is a more detailed schematic illustra- tion of a part of a cargo space 102. According to an embodiment, there is an apparatus for detecting move- ments of cargo on board the vessel. The arrangement comprises a LIDAR 201 that is configured to generate measurement data. As is known for LIDARs, the measure- ment data represents primarily distance measurements, so that each individual piece of measurement data is an indication of a distance between the current posi- tion of the LIDAR and the surface from which a partic- ular laser pulse (or group of laser pulses) reflected. The measurement data may comprise additional infor- mation, such as an indication of the reflectivity of the surface from which the laser pulse (or group of laser pulses) reflected.

The apparatus comprises also a conveyor 202 configured to convey the LIDAR 201 within the cargo space 102 of the vessel while the vessel is en route. This capability of the conveyor 202 means that it uses resources (structure, communications, operating power, and the like) that are available on board while the vessel is out on the sea. It means also that the oper- ation of the conveyor 202 must not be blocked by some = measures, like the closing of watertight doors or N hatches, that are required to be in place while the S 30 vessel is en route. Further it requires that the 2 structure and operating means of the conveyor 202 are Ek robust enough so that the forces and stresses caused * by ship moving through high seas do not keep the con- 3 veyor 202 from operating. Yet another requirement is o 35 that the typical environmental conditions, like tem- S perature and humidity, within the cargo space 102 mustnot have any significant hampering effect on the oper- ation of the conveyor 202. As an example, the conveyor 202 may comprise one or more rails mounted at or close to a ceiling 203 5 of the cargo space 102. The LIDAR 201 may comprise rollers and/or sliders that allow it to move along such rails, as well as one or more electric motors, pulleys, magnetic motors, and/or other propulsion units that produce the necessary propelling force.

Placing the conveyor 202 high up in the cargo space 102 is advantageous, because the LIDAR measurement is based on linearly propagating light, and high up in the cargo space 102 there is typically most free space available for the propagation of light.

Also, high up in the cargo space 102 it may be easiest to find an installing location for the conveyor 202 at which it does not interfere too much with the actual use of the cargo space 102 for loading, transporting, and unload- ing cargo.

Figs. 3 to 6 illustrate some examples of how the conveyor 202 may be located with respect to a floor plan of a cargo space.

Fig. 3 illustrates a rel- atively simple alternative, in which a single rail 301 is installed along a centerline of an elongated cargo space.

Fig. 4 illustrates an alternative in which there are two individual rails 401 and 402 installed so that the required horizontal reach of the LIDAR = does not become as long as in the alternative of fig.

N 3. Each rail 401 and 40? may have its own LIDAR moving S 30 along the rail, or there may be a crossbar rail or 2 other transferring arrangement through which the LIDAR Ek may move from one rail to another and back. * Fig. 5 illustrates a yet more elaborate al- x ternative in which a network 501 of rails is installed o 35 across the ceiling of the cargo space.

A natural re- S quirement of such a more elaborate alternative is that the LIDAR must be equipped for moving through railcrossings and for turning around corners, while in the alternatives of fig. 3 and 4 it is sufficient to equip the LIDAR for moving back and forth along a single rail (with possible additional transferring movement in fig. 4). Fig. 6 illustrates an arrangement in which there are three separate cargo spaces 601, 602, and 603, each equipped with its own respective conveyor 604, 605, or 606. This kind of an arrangement is ad- wvantageous for example if the classification of the vessel requires all cargo spaces to be separated from each other.

Fig. 6 illustrates also another possible feature of the arrangement that can be implemented in any embodiment: in some cases it may be more important to place the conveyor so that the LIDAR can be con- veyed more along the perimeter of the cargo space than at its center.

This is because if the cargo begins to move, the movements may be more easily detectable at the edges of the amount of cargo in the cargo space than at its center.

If structural factors and classification specifications allow, it may be advantageous to con- figure the conveyor to convey the LIDAR between two or more separate cargo spaces.

Fig. 7 illustrates an ex- ample, in which there are two cargo spaces 102 and 103 at different levels within the vessel.

The convevyor 701 of fig. 7 is configured to convey the LIDAR 201 x horizontally within each of the two cargo spaces 102 N and 103, but also vertically between them.

This kind S 30 of embodiments involve the advantage that only one LI- 2 DAR is needed in the whole vessel, or at least there Ek are needed fewer LIDARs than if each cargo space would * have its own LIDAR.

In all embodiments it is also pos- x sible to implement the conveyor so that the LIDAR may o 35 move in three dimensions (i.e. not only in a single S plane close to the ceiling) within any individual car-

go space.

This can be accomplished for example by ex-

tending a network of rails also to some portion of the vertical walls of the cargo space.

Some or all parts of the conveyor may be equipped with hinges, telescopic supports, sliding mounts, or other means for moving those parts of the conveyor between at least two positions, one of which may be a stowed position and another of which may be a use position.

In such a case those parts of the con- veyor that are movable can be moved to the stowed po- sition for example for the duration of loading or un- loading cargo, ensuring that no part of the conveyor comes in the way.

Fig. 8 is an example of a block diagram of the LIDAR 201. A measurement head 801 comprises the optical transmitter and receiver that perform the ac- tual transmission and reception of laser pulses.

In the embodiment of fig. 8 the measurement head 801 also generates the pieces of measurement data, i.e. the in- dividual distance values that constitute the LIDAR measurement results.

One measurement head may contain one transmitter and one receiver, and there may be a plurality of measurement heads.

As an alternative there may be only one measurement head but it can be equipped with a plurality of transmitters and/or a plurality of receivers.

A movement robotics block 802 is responsible for the movements of the LIDAR along the conveyor. 2 Making a measurement head move along a dedicated con- N veyor is known as such from various applications of S 30 measurement technology, so the implementation of the 2 movement robotics block 802 does not need to be ana- = lyzed here in more detail. * A LIDAR controller 803 controls the operation x of the LIDAR.

In the embodiment of fig. 8 it comprises o 35 for example a movements control block 804, which gives S instructions to and receives feedback from the move- ment robotics block 802. The LIDAR controller 803 com-

prises also a data collector 805 that is configured to collect sets of the measurement data coming from the measurement head(s) 801. The data collector 805 may also give commands and instructions to the measurement head(s) related to the collection of data, like com- mands of beginning and ending a measurement.

As used here, the term set of measurement da- ta means an amount of data that represents a topogra- phy of cargo within a particular region of a cargo space. The LIDAR can be said to repeatedly generate a three-dimensional map of the cargo within the region it "sees”, i.e. the region from which the LIDAR can receive reflections of its transmitted laser pulses. In order to generate such a three-dimensional map there is needed also information from the movements control block 804, unless the measurement head 801 can itself tell, where along the conveyor it was when each individual measurement was made. The last-mentioned is possible if the measurement head 801 comprises, in ad- dition to the LIDAR transmitter(s) and receiver(s), some kind of location sensors.

As long as the cargo does not move, each set of measurement data is equal to the others. In other words, the three-dimensional map that the LIDAR gener- ates of the cargo remains the same. A movement of the cargo can be detected by noticing that a change has occurred: a three-dimensional map generated later is = not any more the same as earlier. N A difference detector 806 in the LIDAR con- S 30 troller 803 is configured to detect a difference be- 2 tween two sets of measurement data that represent a Ek same region of the cargo space. There are many ways to * implement the difference detection in practice. One 3 example is to generate a so-called difference map, o 35 which is the arithmetical difference between two sets S of measurement data. Each set of measurement data can be considered as a two-dimensional matrix of distancevalues, or a matrix of three-dimensional coordinate points. A difference matrix can be calculated, in which from each element of one matrix is subtracted the corresponding element of the other matrix. If the sets of measurement data were the same, i.e. if the cargo did not move between the respective rounds of LIDAR mapping, the difference matrix is just full of zeroes (or very small values, because random errors in the measurement cause two subsequent LIDAR mappings to never produce exactly the same result).

The difference detector 806 may be configured to look for the largest value in a difference matrix and compare it to a predefined threshold. If the value remains smaller than said threshold, the difference detector 806 may deduce that there was no significant movement of cargo. Alternatively the difference detec- tor 806 may be configured to collect all elements of the difference matrix that are larger than a predeter- mined threshold and examine, whether this group of el- ements fulfils one or more predetermined decision cri- teria, like having an average value larger than a threshold or all being concentrated at some relatively limited region in the cargo space. The last-mentioned might mean that a single piece or some limited amount of cargo has moved while other parts of the cargo have remained steady.

Another example of how the difference detec- 2 tor 806 may operate involves comparing some statisti- N cal descriptors or other derived values of the sets of S 30 measurement data. Mean values, standard deviations, 2 and variances of measurement data can be used as sta- Ek tistical descriptors, but also determinants, eigenval- * ues, or other values known from matrix calculus can be x used. The use of statistical descriptors or other de- o 35 rived values involves the advantage that not as much S storage space is needed for the stored data. Also hy- brid embodiments are possible, for example so that on-

ly every Nth set of measurement data is stored as such, where N is a positive integer, and for the in- termediate sets of measurement data there are stored only some more condensed forms, like statistical de- scriptors or other derived values.

Cargo may move abruptly, or there may be slow, more gradual movements.

In order to be able to detect both, it may be advantageous to configure the difference detector 806 so that it compares a most re- cently obtained set of measurement data to the immedi- ately previous one, but also to one or more earlier ones, like to the very first set of measurement data that was collected when the vessel left port the last time.

The difference detector 806 may also be con- figured to compose various kinds of time series of the differences it may have detected between the sets of measurement data.

A time series may reveal a creeping trend of cargo movement, or some oscillating movement caused by some part of the cargo being loosely secured so that it moves back and forth.

Oscillating movement tends to cause repeated loading and conseguently fa- tigue in materials, which may have far-reaching ef- fects even if no visible problems with the cargo would actualize during the current journey of the vessel.

The lidar controller 803 may be configured to generate an indication of a detected difference and to = transmit said indication towards a recipient, which N may mean a receiving device or a human recipient.

This S 30 is not an obligatory part of operation, for example if 2 the purpose of the system is only to monitor the cargo Ek over a longer term and to record oscillating or other * movements of which maintenance personnel might be in- 3 terested in the future.

However, generating and indi- o 35 cation of a detected difference is advantageous in S those cases where immediate or otherwise timely actionis desired in response to detected movements of cargo.

The block diagram of fig. 8 illustrates a communications interface 807, through which the lidar controller 803 may transmit such an indication towards a recipient. All possible recipients are represented in the block diagram as external systems 808. In some embodiments the controller is configured to transmit said indication to an onboard control system of the vessel. Such embodiments involve the advantage that the onboard control system of the vessel can take im- mediate action, for example by producing a visual, au- dible, or otherwise easily detectable alert to a crew member. If the vessel is a remotely operated unmanned vessel, the onboard control system may decide to take some action to avoid any harmful or dangerous conse- guences of the detected movements of the cargo. For example, the onboard control system may make a change to a previously determined heading so that a rolling movement of the vessel would decrease.

In some embodiments the controller is config- ured to transmit said indication to a remote onshore control centre. Such embodiments involve the advantage that a remote operator may be alerted of a possikly risky situation that may be developing on board the vessel. If the decisions about changes in heading or other evasive action are to be made by the remote op- erator, an indication transmitted to the remote on- shore control centre may include also other helpful = information, like a suggestion of a new heading. N The lidar controller 803 may take also inter- S 30 nal action in response to a detected difference be- 2 tween two sets of measurement data that represent a Ek same region of said cargo space. As an example the * controller may be configured to respond to a detected x difference by making the LIDAR generate one or more o 35 additional sets of measurement data of that particular S region of the cargo space. An additional set of meas- urement data may serve as a confirmation that tells,

whether a movement of cargo has actually taken place or whether the previously detected difference was caused just by some random error.

One or more addi- tional sets of measurement data may be advantageous also because they may focus the subsequent monitoring to a region of the cargo space that has been found to involve an elevated risk of cargo movement.

Another type of internal action may involve the way in which stored data is handled.

If the LIDAR measurement is operational throughout a journey that may take weeks, and if no movements of cargo actually take place, a relatively large amount of measurement data may become stored to little actual avail.

In or- der to save storage space of data, the data collector 805 or some other part of the lidar controller 803 may be configured to discard, compress, and/or otherwise decrease the amount of such previously generated meas- urement data that did not give rise to any action.

If a difference of any significance is found between two sets of measurement data that represent the same re- gion of the cargo space, the lidar controller 803 may initiate a change in the data handling routines so that more data will be stored than if no such differ- ences were found.

Not all of the functional parts illustrated in the block diagram of fig. 8 need be included in the mobile unit that actually moves in the cargo space(s) = as conveyed by the conveyor.

According to one embodi- N ment the mobile unit comprises only the measurement S 30 head(s) 801 and the necessary parts of the movement 2 robotics 802, while all other parts of the LIDAR appa- =E ratus are located in a cabinet or rack or other fixed * installation location.

As will be described in more 3 detail later, it is not even obligatory to have all o 35 the functional blocks of fig. 8 on board the vessel: S some of them may well be located e.g. on board anothervessel or in the remote onshore control centre, if thenecessary communications connections can be arranged reliably enough.

Fig. 9 illustrates an example of how an appa- ratus of the kind described above may operate as a part of an automated monitoring and diagnostic system of a vessel.

In the system architecture of fig. 9 the LIDAR 201 is one of the sensor systems that a vessel diagnostics central computer 901 has at its disposal.

One example of other sensor system is an acoustic sen- sor system 902, which may be configured to record au- dible sounds transmitted through air but also other acoustic phenomena, like signals on acoustic freguen- cies that are transmitted internally along metal structures.

Another example is a mechanical sensor system 903, which may comprise for example strain gauges installed in various locations of the structure of the vessel.

Also other kinds of sensor systems 904 can be used.

The LIDAR 201 and acoustic 902 sensor systems may even share some parts and functionalities.

As an example, the mobile unit conveyed within the cargo space(s) by the conveyor may comprise, in addition to the measurement head(s) of the LIDAR 201, acoustic transducers that may continuously perform a kind of sonar measurements of the cargo space(s). Augmenting a LIDAR measurement with a sonar or other acoustic meas- urement may increase the reliability of the measure- 2 ment and provide valuable additional information for N example in such cases where a change in the acoustic S 30 characteristics (like change in acoustic reflectivity 2 due to continuously increasing amount of absorbed wa- =E ter) may anticipate an increasing risk of cargo move- > ments. x As examples of interfaces fig. 9 shows an ex- o 35 ternal systems interface 905, through which the vessel S diagnostics central computer can communicate with e.g. an onboard control station configured to determine andmaintain a heading of said vessel. The onboard control station may be configured to receive, through the ves- sel diagnostics central computer 901, an indication of a detected difference from the LIDAR 201 and to re- spond to said received indication by making a change to a previously determined heading. Additionally fig. 9 illustrates a user interface 906 through which the vessel diagnostics central computer 901 can communi- cate with a human user.

One possible functionality that may be a functionality of the LIDAR system and/or a functional- ity of the vessel diagnostics central computer 901 is using at least one set of measurement data to identify at least one item of cargo within the cargo space.

Such a functionality may be useful both in situations where no unintended cargo movements have been observed and in situations in which some cargo movements have occurred. As is known the general technology of LI- DARs, the set of measurement data or map produced by a LIDAR is essentially a three-dimensional point cloud, in which each point represents a detected reflection from a surface. If the point cloud is dense enough, it may be possible to detect some three-dimensional forms from which it can be identified, what type of a cargo item was in question.

This “cargo identifying” functionality may utilize additional information, like for example a da- = tabase of previously identified cargo items, to per- N form a kind of machine learning so that a subsequent S 30 detection of a similar form may be identified more re- 2 liably. Another type of additional information may be =E a list of cargo items that have been loaded, so that * instead of trying to blindly identify a detected 3 three-dimensional form the “cargo identifying” func- o 35 tionality would only need to compare it to the list S and find the most probable match.

Identifying cargo items that have moved may give useful additional information. For example, if a cargo movement has been detected and the shifted item is identified by its form to be a heavy truck, the situation may need more immediate action than if the shifted item was something lighter. Additionally or alternatively the information about identified cargo items may be used to estimate the center of gravity of the whole cargo, to identify particularly hazardous cargo items like particularly flammable materials, to give estimates of ship loading or unloading process, or the like.

Fig. 10 illustrates schematically a situation in which a remotely operated unmanned vessel 1001 maintains a constant or regular communications connec- tion 1002 with a remote onshore control centre 1003. There are a plurality of possible ways in which the parts and functionalities of a LIDAR-based cargo space monitoring system can be divided between these two.

As a kind of a first extreme alternative, all parts of the LIDAR-based cargo space monitoring system may be on board the vessel 1001, so that possibly only some information is transmitted over the communica- tions connection 100? to the remote onshore control centre 1003 about what kind of observations the auton- omous vessel diagnostics system of the vessel 1001 has made and what actions it has taken on the basis there- = of. As was pointed out above, it is not even necessary N to communicate with the remote onshore control centre S 30 1003 about detected movements of cargo, if the purpose 2 of the LIDAR-based cargo space monitoring system is Ek only to collect measurement data for later use in * checking the structures of the vessel for fatigue and 3 performing maintenance operations. o 35 As a kind of a second extreme alternative, S the LIDAR-based cargo space monitoring system may be implemented so that only the LIDAR measurementhead (s), the conveyor(s), and some kind of a data col- lector are located on board the vessel 1001, as well as some kind of a communications interface that could transmit the collected data to the remote onshore con- trol centre 1003 for further analysis.

In addition to requiring the installation of only a relatively lim- ited amount of electronics on board the vessel 1001, such an embodiment involves the advantage that a maxi- mum amount of information is available at the remoteonshore control centre 1003. If measurement data are collected from a plu- rality of vessels, the remote onshore control centre 1003 can compare the measurement data from different vessels to each other.

Together with other data that the remote onshore control centre 1003 has available, like data about the routes taken by the various ves- sels and the weather conditions they have encountered, his may lead to noticing some tendencies in measure- ment data that point at some predicted course of de- velopment.

These, in turn, can be used to proactively make a vessel change its heading or make some other evasive action even before the movements of its cargoreach alarming proportions.

Intermediate embodiments between the two ex- tremes described above can be presented, with differ- ent distributions of the parts and functionalities.

In one advantageous embodiment the blocks shown in fig. 8 x are all implemented on board of the vessel, which fa- N cilitates timely reactions to detected movements of S 30 cargo even in situations where the communications con- 2 nection to a remote onshore control centre is not im- =E mediately available.

In such an embodiment it is nev- + ertheless advisable to make the LIDAR controller 803 3 utilize its communications interface 807 to transmit o 35 to the remote onshore control centre at least some in- S dications of all detected movements of cargo, so thatthe ultimate control of the situation is maintained at the remote onshore control centre.

Fig. 11 illustrates a method according to an embodiment.

Fach of the ovals in fig. 11 illustrates a process or routine that can run independently and that can exchange information with other processes.

Part 1101 of the method comprises using a LI- DAR to generate at least two sets of measurement data.

Fach of said sets is a kind of three-dimensional map that represents a topography of cargo within a partic- ular region of a cargo space of the vessel.

In order to serve the purposes of detecting movements of cargo on board the vessel, this part of the method is exe- cuted while said vessel 1s en route.

Part 1102 of the method comprises storing said sets of measurement da- ta; they are called maps in fig. 11 for conciceness.

Parts 1103 and 1104 of the method comprise detecting a difference between two sets of measurement data, and generating an indication of such a detected difference and transmitting said indication towards a recipient.

The differences may be detected by compar- ing different sets of measurement data to each other at part 1103, and communicating any detected differ- ences to part 1104 in which all exceptions are han- dled.

An exception means for example a situation in which a significant difference between two sets of measurement data have been found, indicating that some 2 of the cargo has moved.

As described above, transmit- N ting said indication towards a recipient at part 1104 S 30 of the method may comprise transmitting said indica- 2 tion for example to a remote onshore control centre Ek and/or to an onboard control system of the vessel. * The information that flows from part 1101 to x part 1102 of the method comprises the "maps”, i.e. the o 35 sets of measurement data.

In the reverse direction S part 1102 may communicate to part 1101 of the method for example requests of obtaining maps of certain re-

gions of the cargo space of which the previous maps have become obsolete.

The information that flows from part 1102 to part 1103 of the method comprise the “maps”, i.e. sets of measurement data that are to be compared. In the reverse direction part 1103 may communicate to part 1102 of the method for example instructions of how certain parts of previously obtained measurement data can be discarded or compressed, because the compari- sons have revealed nothing interesting in them.

The information that flows from part 1103 to part 1104 of the method comprise the indications of detected differences between sets of measurement data. In the reverse direction part 1104 may communicate to part 1103 of the method for example requests of a more careful analysis between two sets of measurement data in which part 1103 initially found a difference of which it provided an indication to part 1104.

The information that flows from part 1104 to part 1101 may comprise for example instructions to perform an immediate rescan of a region of the cargo space in which some movements of cargo have been de- tected or suspected. In the reverse direction part 1101 may communicate to part 1104 of the method for example information about exceptional situations en- countered in the process of generating measurement da- ta, like a malfunction of the conveyor that keeps the x measurement head from reaching some region of the car- N go space. S 30 The information that flows from part 1104 to 2 external processes may comprise for example the indi- Ek cations of detected differences between sets of meas- * urement data, possibly in some more refined form like 3 augmented with an announcement that a detected differ- o 35 ence has been verified with a rescan of the affected S region of the cargo space. In the reverse direction part 1104 may receive any instructions from externalsystems, like instructions to reconfigure the LIDAR- based measurement process. It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways. The invention and its embodiments are thus not limited to the examples described above; instead they may vary within the scope of the claims. As an exam- ple, even if the embodiments described so far may have involved an assumption that the LIDAR uses only direct reflections for measurement, this is not a requirement of the invention. Aiming at the best economy and best usage of transporting resources may mean that the car- go space of a vessel becomes so full that the LIDAR cannot see to all parts of the cargo space. In such cases it may be possible to equip some parts of the cargo space with mirrors that reflect both the initial laser beam and its reflections. With the help of such mirrors the LIDAR can be made to “see” to such loca- tions of the cargo space to which a direct laser beam would not propagate. 00

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Claims (14)

1. An apparatus for detecting movements of cargo (104) on board a vessel (101, 1001), comprising: - a LIDAR (201) configured to generate measurement da- ta; - a conveyor (202) configured to convey said LIDAR (201) within a cargo space (102, 103) of said vessel (101, 1001) while said vessel is en route; and - a data collector (805) configured to collect sets of said measurement data.

2. An apparatus according to claim 1, com- prising: - a difference detector (806) configured to detect a difference between two sets of said measurement data that represent a same region of said cargo space (102, 103); and - a controller (803) configured to generate an indica- tion of a detected difference and to transmit said in- dication towards a recipient.

3. An apparatus according to any of claims 1 or 2, wherein said conveyor (201) comprises one or more rails (301, 401, 402, 501, 604, 605, 606) mounted at or close to a ceiling of said cargo space (102, 103).

4. An apparatus according to any of the pre- = ceding claims, wherein said conveyor (102) is config- N ured to convey said LIDAR (201) between two or more S separate cargo spaces (102, 103).

oO >

5. An apparatus according to any of the pre- Ao a 30 ceding claims, wherein said controller (803) is con- 2 figured to transmit said indication to an onboard con- 3 trol system of the vessel (101, 1001).

O N

6. An apparatus according to any of the pre- ceding claims, wherein said controller (803) is con-

figured to transmit said indication to a remote on- shore control centre (1003).

7. An apparatus according to any of claims 2 to 6, wherein said controller (803) is configured to respond to a detected difference by making said LIDAR (201) generate one or more additional sets of measure- ment data of said region of the cargo space (102, 103).

8. A vessel (101, 1001) comprising the appa- ratus of any of the preceding claims.

9. A vessel according to claim 8, wherein: - said vessel (101, 1001) is a remotely operated un- manned vessel; - said vessel comprises an onboard control station configured to determine and maintain a heading of said vessel (101, 1001); - said onboard control station is configured to re- ceive an indication of a detected difference from said apparatus and to respond to said received indication by making a change to a previously determined heading.

10. A method for detecting movements of cargo on board a vessel, comprising: - using a LIDAR to generate (1101) two sets of meas- urement data (1102) representing a topography of cargo © 25 within a same region of a cargo space of said vessel a while said vessel is en route.

S o 11. A method according to claim 10, compris- A ing: z - detecting (1103) a difference between said two sets o 30 of measurement data; and 2 - generating (1103) an indication of said detected = difference and transmitting (1104) said indication to- N wards a recipient.

12. A method according to claim 11, wherein sald transmitting (1104) comprises transmitting said indication to a remote onshore control centre.

13. A method according to claim 11, wherein said transmitting (1104) comprises transmitting said indication to an onboard control system of said ves- sel.

14. A method according to any of claims 10 to 13, comprising using at least one set of measurement data to identify at least one item of cargo within said cargo space. 00

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