Patent Publication Number: US-11661721-B2

Title: Apparatus and method for seabed resources collection

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to the Singapore Application No. 10201902911Y, filed Apr. 1, 2019, now pending, the contents of which are hereby incorporated by reference. 
     FIELD OF INVENTION 
     The invention generally relates to an apparatus for collecting seabed resources wherein the apparatus includes a plurality of collecting devices configured to collect seabed resources along a predetermined mining path, and a method thereof. 
     BACKGROUND 
     It is known that exploration and exploitation of seabed resources, e.g. seabed nodules or ores, are essential to obtaining mineral resources to satisfy the gradually increasing demand for mineral resources. Despite the variety of apparatuses proposed for the seabed resources collection, the process of collecting seabed resources in deep oceans and transferring the collected resources from the seabed to a surface ship in an efficient manner remains difficult. 
     U.S. Pat. No. 4,685,742 A discloses an apparatus for extracting ores from the seabed. This apparatus includes a plurality of collecting devices for collecting seabed ores, and a relay unit configured to raise the collected seabed resources to a surface vessel through a raising conduit. However, with this apparatus, the efficiency of collecting seabed resources may be very low due to overlapping of working areas of different collecting devices and undesired obstacles on the relevant seabed. 
     Another apparatus for collecting seabed resources proposed in KR 1369830 B1 includes a plurality of collecting robots/devices for collecting seabed resources, and an area dividing device configured to generate signals to divide the relevant seabed, i.e. the seabed on which the apparatus is to collect seabed resources, into different working areas for different collecting robots/devices. In this solution, although different collecting robots/devices are assigned respective working areas, the efficiency of collecting seabed resources is still very low. 
     Other different system/apparatus for seabed resources collection are also described in patent publications, e.g. a system for recovering a deposit from the seabed disclosed in US20140230287A1 and a deep sea mining system disclosed in CN2016158747U. 
     It is therefore desirable to provide a solution for collecting seabed resources in a more efficient manner. 
     SUMMARY OF INVENTION 
     In order to provide a more efficient solution for seabed resources collection, embodiments of the invention discloses various systems and methods for collection and transfer of seabed resources. 
     According to one aspect of the invention, an apparatus for collecting seabed resources is provided. The apparatus comprises: 
     a main module and a plurality of seabed resources collecting devices releasably attached to the main module, 
     wherein the main module and the plurality of collecting devices are configured to be launched from a surface vessel towards a seabed; 
     wherein the main module includes a control module which is configured to determine a mining path for each of the collecting devices based on characteristics of the seabed, control each of the collecting devices to collect seabed resources along the determined mining path and control transfer of seabed resources collected by the collecting devices, 
     wherein each collecting device is configured to be released from the main module after the apparatus is launched, and to collect seabed resources along the mining path determined by the main module after being released. 
     In some embodiments of the invention, the apparatus including the main module together with the collecting devices is launched from the surface vessel and is positioned at a predetermined height above the seabed. 
     In some embodiments of the invention, the apparatus including the main module together with the collecting devices is launched from the surface vessel and landed on the seabed. 
     In some embodiments of the invention, the collecting devices are movably and communicably connected to the main module for power transfer from the main module to the collecting devices, resources transfer from the collecting devices to the main module and communication therebetween. 
     In some embodiments of the invention, after the collecting devices are released from the main module, the collecting devices are communicated with the main module in a wireless manner as there are no physical connections between the collecting devices and the main module. 
     According to another aspect of the invention, a method for collecting seabed resources is provided. The method comprises: 
     launching an apparatus for collecting seabed resources from a surface vessel towards a seabed, wherein the apparatus includes a main module and a plurality of collecting devices releasably attached to the main module; 
     determining, by the main module, a mining path for each of the plurality of collecting devices based on characteristics of the seabed; 
     releasing the plurality of collecting devices from the main module; 
     controlling, by the main module, each of the collecting devices to collect seabed resources along the mining path determined by the main module; and 
     controlling, by the main module, transfer of the seabed resources collected by the collecting devices. 
     With the apparatus and method provided in embodiments of the invention, the mining path of each of the plurality of collecting devices can be controlled by the main module of the apparatus according to the information relating to the characteristics of the relevant seabed. Further, the transfer of the seabed resources from the collecting devices to the main module and/or from the main module to the surface vessel is also controlled by the main module. Thus, the efficiency of the seabed resources collection can be significantly improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described in detail with reference to the accompanying drawings, in which: 
         FIG.  1 A  shows a perspective view of an apparatus for collecting seabed resources when the apparatus is being lowered from a surface vessel according to a first embodiment of the invention; 
         FIG.  1 B  shows a perspective view of the apparatus of  FIG.  1 A  when it is in use or operational state according to the first embodiment of the invention; 
         FIG.  1 C  shows a perspective view of a collecting device according to the first embodiment of the invention; 
         FIG.  1 D  shows a thruster assisted Vertical Transport System (VTS) provided to assist in transfer of seabed resources to the surface vessel according to the first embodiment of the invention; 
         FIG.  1 E  shows a side perspective view of the thruster assisted Vertical Transport System (VTS) of  FIG.  1 D  according to the first embodiment of the invention; 
         FIG.  1 F  is a flow chart illustrating a method for collecting seabed resources using the apparatus according to the first embodiment of the invention; 
         FIG.  2 A  is a perspective view of an apparatus for collecting seabed resources when the apparatus is being lowered from a surface vessel according to a second embodiment of the invention; 
         FIG.  2 B  is a perspective view of the apparatus in  FIG.  2 A  when it is in use; 
         FIG.  2 C  is a bottom perspective view of the apparatus in  FIG.  2 A  when it is in use; 
         FIG.  3 A  is a top perspective view of an apparatus for collecting seabed resources according to a third embodiment of the invention; 
         FIG.  3 B  shows a side perspective view of the apparatus in  FIG.  2 A  when the apparatus is in use; 
         FIG.  3 C  shows a side perspective view of the main module in the apparatus shown in  FIG.  3 A ; 
         FIGS.  4 A to  4 C  provide three different types of filtering modules which can be interchangeably used in the apparatus for collecting seabed resources; 
         FIG.  5    is a flow chart illustrating a method for collecting seabed resources using the apparatus in  FIGS.  3 A to  3 C  according to the third embodiment of the invention; 
         FIG.  6 A  shows a process of launching the apparatus from a surface vessel to the seabed according to the third embodiment of the invention; 
         FIG.  6 B  shows a surface vessel having an A-shaped frame; 
         FIG.  7    shows a connection between an intervention ROV and a main module after the intervention ROV is launched from the main module; 
         FIG.  8    shows two seabed sitting frames launched from the surface vessel and landed on the seabed according to the third embodiment of the invention; 
         FIG.  9    shows two containers which are launched from a surface vessel and respectively positioned on/at different seabed sitting frames according to the third embodiment of the invention; 
         FIG.  10    shows one container which is connected to the main module through a connecting hose by the intervention ROV and another container being lowered towards the seabed according to the third embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     In the following description, numerous specific details are set forth in order to provide a thorough understanding of various illustrative embodiments of the invention. It will be understood, however, to one skilled in the art, that embodiments of the invention may be practiced without some or all of these specific details. It is understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention. In the drawings, like reference numerals refer to same or similar functionalities or features throughout the several views. 
     Embodiments described in the context of one of the methods or apparatuses are analogously valid for the other methods or apparatuses. Similarly, embodiments described in the context of a method are analogously valid for an apparatus, and vice versa. 
     Features that are described in the context of an embodiment may correspondingly be applicable to the same or similar features in the other embodiments. Features that are described in the context of an embodiment may correspondingly be applicable to the other embodiments, even if not explicitly described in these other embodiments. Furthermore, additions and/or combinations and/or alternatives as described for a feature in the context of an embodiment may correspondingly be applicable to the same or similar feature in the other embodiments. 
     As used herein, the articles “a”, “an” and “the” as used with regard to a feature or element include a reference to one or more of the features or elements. 
     As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     As used herein, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. 
     As used herein, the term “each other” denotes a reciprocal relation between two or more objects, depending on the number of objects involved. 
     As used herein, the terms “pipe” and “hose” are mutually interchangeable and refer to a hollow body or conduit or passage for conveying substances including solid and/or fluid substances. These terms are not intended to impose rigidity or flexibility properties. 
     As used herein, the terms “fluidly connected to” refers to “be in fluid communication with”. For example, if a first module is fluidly connected to a second module, a mixture of liquid and/or solid seabed resources may be transferred from the first module to the second module, and/or vice versa. 
     Embodiments of the invention provide an apparatus for collecting seabed resources wherein the apparatus includes a main module and a plurality of seabed resources collecting devices. The collecting devices are releasably and attached/locked/latched to the main module. The main module, together with the attached collecting devices, is configured to be launched from a surface vessel towards a seabed to start seabed resources collection. After launch, the main module is connected to the surface vessel and remotely controlled by the surface vessel. The main module includes a control module which is configured to determine an exploitation/mining path for each of the collecting devices based on characteristics of the relevant seabed, e.g. bathymetry, geographical features of the relevant seabed (e.g. undulation on the seabed), intensity distribution and volume of the seabed resources on the relevant seabed (e.g. nodule abundance), and soil strength of the relevant seabed, etc. Here, the relevant seabed refers to the seabed or an area thereof on which the apparatus is to collect seabed resources. 
     Further, the main module is also configured to control each of the collecting devices to collect seabed resources along the determined mining path and control transfer of the collected seabed resources, e.g. the transfer of the collected seabed resources from the collecting devices to the main module and/or the transfer of the seabed resources away from the main module to a surface vessel. 
     Each of the collecting devices is configured to be released/unlatched from the main module, and collect seabed resources along the mining path determined by the main module after being released. 
     In some embodiments of the invention, each of the collecting devices is provided with at least one scanning means, e.g. sensor, to scan the seabed to collect information relating to the characteristics of the seabed and send the collected information to the main module. Accordingly, the main module is configured to determine the mining path for each of the collecting device based on the received information. 
     Some examples are provided below to further explain how the main module determines the mining path for each of the collecting devices and how the main module controls each of the collecting devices to collect seabed resources along the determined mining path. 
     The main module may be further configured to determine whether there is overlap between the mining paths of the collecting devices based on the received information, and adjust the mining path for at least one of the collecting devices if there is overlap. 
     In some examples, each of the collecting devices may be configured to scan the seabed to check the soil strength thereof and sends the information relating to the soil strength to the main module. Accordingly, the main module may be configured to analyse the received information to determine tractive force required for the collecting device and control the collecting device to adjust the tractive force. 
     In some examples, each of the collecting devices may be configured to scan the seabed to check nodule abundance thereof and send the information/data relating to the nodule abundance to the main module. Accordingly, the main module may be configured to send an instruction to the collecting device to prepare for collection if the nodule abundance satisfies a predetermined requirement. 
     In some examples, the main module may be configured to determine a collection rate for each of the collecting devices. The collection rate may be determined based on the information/data in relation to the characteristics of the seabed and a predetermined annual collection rate. 
     In some examples, the main module may be configured to update the mining path for each of the collecting devices based on real time information which relate to the characteristics of the seabed and is received from the collecting device. Thus, the mining path of each collecting device can be adjusted timely based on the information relating to the characteristics of the seabed to further improve the efficiency of seabed resources collection. 
     In some examples, each of the collecting devices may be configured to scan the seabed to check its undulation and send the information relating to the undulation to the main module. Accordingly, the main module may be configured to control the collecting device to stop or start seabed resources collection based on the information relating to the undulation, e.g. the slope or degree of the undulation. For example, if the slope of the undulation is greater than a predetermined degree, e.g. 10 degrees, the main module is configured to send an instruction to the collecting device to stop seabed resources collection. Further, the main module may be configured to determine the tractive force required for the collecting device based on the slope degree of the undulation and adjust the tractive force required for the collecting device accordingly. 
     In some examples, the main module may be configured to determine if a turning mechanism is required to be activated based on the real time information relating to characteristics of the seabed and received from the collecting devices, and control the collecting device to stop collection and activate the turning mechanism if necessary. 
     It should be noted that the examples mentioned above are for illustrative purpose only, not for limiting the scope of the invention. In other examples, the main module may determine the mining path for each of the collecting devices based on the characteristics of the seabed and control the collecting devices to collect seabed resources in other ways. 
     In some embodiments of the invention, the whole apparatus including the main module and the collecting devices may be landed on the seabed, while in other embodiments, at least part of the apparatus or even the whole apparatus may be positioned at a predetermined height above the seabed to minimise environment disturbances to the seabed caused by the process of seabed resources collection. 
       FIG.  1 A  shows a perspective view of an apparatus  100  for collecting seabed resources when the apparatus  100  is being lowered from a surface vessel  10  according to a first embodiment of the invention.  FIG.  1 B  shows a perspective view of the apparatus  100  when it is in use according to the first embodiment of the invention. 
     Referring to  FIGS.  1 A to  1 B , in this embodiment, the apparatus  100  includes a main module  110  and two collecting devices  120 . The main module  110  is connected to the surface vessel  10  and remotely controlled by means of power and communication cables from the surface vessel  10 . The two collecting devices  120  are releasably attached to the main module  110 . 
     As shown in  FIG.  1 A , the main module  110 , together with the collecting devices  120 , is lowered/launched from the surface vessel  10  towards the seabed till the whole apparatus  100  hovers at a predetermined height above the seabed. 
     As shown in  FIG.  1 B , after the apparatus  100  is launched and subsequently hovers at the predetermined height above the seabed, the collecting devices  120  are released from the main module  110  and subsequently hover at a predetermined height above the seabed to collect seabed resources. After release from the main module  110 , each of the collecting devices  120  is movably and communicably connected to the main module  110  by a connecting cord  121 . In one example, the connecting cord  121  may be a hybrid flow hose for communication between the main module  110  and the collecting device  120 , power transfer from the main module  110  to the collecting device  120  and resource transfer from the collecting device  120  to the main module  110 . 
     As shown in  FIGS.  1 A and  1 B , the main module  110  includes a control module  111 , a filtering module  112 , a storage module  114 , a seabed resource offloading mechanism  116 , a buoyancy module and frame  117  and vectored thrusters  118 . 
     In the main module  110 , the control module  111  is communicably connected to the surface vessel  10  and each of the collecting devices  120 . The control module  111  is configured to determine a mining path for each of the collecting devices  120  based on the information relating to characteristics of the seabed and control each of the collecting devices  120  to collect seabed resources along the determined mining path. In this embodiment, the information relating to characteristics of the seabed may be collected by the collecting devices  120  using at least one sensor provided thereon. To further improve the efficiency of the seabed resource collection, the control module  111  may be further configured to determine non-overlapping mining paths for the collecting devices based on the received information. 
     The control module  111  may be fluidly connected to each of the collecting devices  120  and configured to control transfer of the collected seabed resources from the collecting devices  120  to the surface vessel  10 . 
     The filtering module  112  is configured to at least partially remove the sediments, e.g. sand particles and/or slurry, from the collected seabed resources. Different types of filtering module  112  may be interchangeably used in the apparatus  100 . Three different types of filtering modules, e.g. a filtering module including a centrifuge system or a water sprinkler system, will be further explained in detail later in this description. The apparatus  100  may include any one of the three different filtering modules which works alone or any combination of the different filtering modules, e.g. the apparatus  100  may include all of the three filtering modules which work together in series, i.e. one after another. 
     In some embodiments, the collected seabed resources may be first transferred to the control module  111  by a pump assembly provided in the main module  110  and then transferred to the filtering module  112  through an interface between the control module  111  and the filtering module  112 . 
     The storage module  114  is configured to temporarily store the filtered seabed resources before the seabed resources are transferred away from the main module  110 . The filtered seabed resources may be transferred to the storage module  114  through an interface between the filtering module  112  and the storage module  114 . 
     The interface between the control module  111  and the filtering module  112  or the interface between the filtering module  112  and the storage module  114  may include at least one hose and a pump assembly. The hose may include a valve which only allows one-way flow transfer of the seabed resources. 
     It should be noted that in some other embodiments, the seabed resources may be transferred directly from the collecting devices  120  to the filtering module  112  for filtration. That is to say, in some embodiments, the apparatus may not include an interface between the control module  111  and the filtering module  112  for transferring seabed resources and the control module  111  is only used to control transfer of the seabed resources from the collecting devices  120  to the filtering module  112 , e.g. by means of a valve arranged between a collecting device  120  and the filtering module  112 . 
     As shown in  FIG.  1 A  and  FIG.  1 B , the apparatus  100  may further include a buoyancy module and frame  117  and vectored thrusters  118  which are configured to counteract drag forces from the seabed current such that the apparatus  100  can move along a substantially vertical path and not sway in horizontal direction. It is to be appreciated that the number of the vectored thrusters used in the apparatus  100  may vary depending on, e.g. the number of the collecting devices  120  included in the apparatus  100 . 
       FIG.  1 C  shows a perspective view of a collecting device  120  according to the first embodiment of the invention. In this embodiment, each collecting device  120  includes a propulsion means  120   a , at least one scanning means  120   b  (not shown in  FIG.  1 C ), a resource collecting means  120   c  and a resource storage module  120   d.    
     The propulsion means  120   a  is configured to enable the collecting device  120  to hover above the seabed or prevent the collecting device  120  from landing or sinking to the seabed. The at least one scanning means  120   b  may be at least one sensor or other scanning device which is configured to obtain information relating to characteristics of the seabed. The resource collecting means  120   c  is configured to collect seabed resources at least along the mining path determined by the main module  110 . 
     The resource storage module  120   d  is configured to temporarily store the seabed resources collected by the resource collecting means  120   c  before the collected seabed resources are transferred away from the collecting device  120 . 
     It is to be appreciated that the resource storage module  120   d  is an optional component, and in some embodiments of the invention, the collecting device may not include the resource storage module. 
     To more efficiently transfer the seabed resources from the main module  110  to the surface vessel  10 , referring to  FIG.  1 D , the apparatus  100  may be further provided with a conveying system. The conveying system includes a thruster assisted Vertical Transport System (VTS)  140 . The VTS  140  may be connected to the surface vessel  10  by an umbilical for power transfer and communication therebetween and configured to assist in transferring seabed resources stored in the main module  110  to the surface vessel  10 . 
     Specifically, the VTS  140  is configured to be launched/lowered from the surface vessel  10  to a position near the main module  110  by side launching using launching rope(s) and a deck crane or winch. After launch, the VTS  140  is configured to be engaged with/fluidly connected to the main module  110  to receive seabed resources from the main module  110 . After at least partially filled with seabed resources, the VTS  140  is configured to be lifted up to the surface vessel  10 , e.g. by a winch or deck crane on the surface vessel  10 . Thus, the seabed resources stored in the main module  110  is transferred to the surface vessel  10  with assistance of the VTS  140 . 
     In some embodiments, the VTS  140  may include a vectored thruster  140   a , a storage container  140   b  and a connecting means  140   c  as shown in  FIG.  1 E . The vector thruster  140   a  is configured to counteract drag forces due to seabed current such that the VTS  140  can move along a substantially vertical path between the seabed and the surface vessel  10  or seawater surface. Besides that, the vector thruster  140   a  is also used to assist in station keeping and dynamic positioning of the VTS  140 , e.g. maintain the VTS  140  at a desired location relative to the surface vessel  10  and ensure the VTS  140  can move along the desired path and heading. The container  140   b  is configured to store the seabed resources transferred from the main module  110 . The connecting means  140   c , e.g. a receptacle, tube, is configured to engage with the main module  110  to enable transfer of seabed resources from the main module  110  to the VTS  140 . For example, the connecting means  140   c  is engaged or fitted with the seabed resource offloading mechanism  116  to provide a passage for resource transfer from the main module  110  to the VST  140 . The pump assembly in the main module  110  may be used to facilitate transfer of the seabed resources from the main module  110  to the VST  140 . 
       FIG.  1 F  is a flowchart illustrating a method of collecting seabed resources using the apparatus  100  according to the first embodiment of the invention. 
     In block  101 , the apparatus  100  is launched, e.g. lowered, from the surface vessel  10  to a predetermined height above the seabed, i.e. an intermediate position between the seabed and the surface vessel or seawater surface, e.g. 100 meters above the seabed. 
     The height of the apparatus  100  may be determined by an altimeter provided on the apparatus  100 . 
     In block  102 , the plurality of collecting devices  120  are released from the main module  110 , and each collecting device  120  hovers at a predetermined location above the seabed. At this time, apparatus  100  is in an extended position wherein at least some of the collecting devices  120  are unlatched from the main module  100  and spread out. 
     In this embodiment of the invention, the whole apparatus  100  is positioned at a predetermined height above the seabed to minimize environment disturbances to the seabed caused by the process of collecting seabed resources. 
     In block  103 , each collecting device  120  collects, by the at least one scanning device, information relating to characteristics of the seabed and transfers the information to the main module  110 . 
     In this embodiment, the characteristics of the relevant seabed may be selected from the group consisting of bathymetry, geographical features of the relevant seabed, intensity distribution and volume of seabed resources on the relevant seabed, and soil strength of the relevant seabed. 
     In block  104 , the main module  110 , particularly the control module  111 , determines a mining path for each of the collecting devices  120  based on the received information relating to the characteristics of the seabed. 
     To further improve the efficiency of the resources collection, the control module  111  may further determine whether there is overlap between the mining paths for the collecting devices  120  based on the received information relating to the characteristics of the seabed, and adjusts the mining path for at least one collecting device  120  to avoid overlap of mining paths. 
     In block  105 , the main module  110  controls each collecting device  120  to collect seabed resources along the mining path determined by the main module  110  and transfer the collected seabed resources to the main module  110 . 
     The transfer of the seabed resources from the collecting devices  120  to the main module  110  is conducted by using a pump assembly provided at the main module  110  through the connection cord  121  between the collecting devices  120  and the main module  110 . 
     In block  106 , sediments, e.g. sand particles and/or slurry, are at least partially removed from the seabed resources by using the filtering module  112  provided at the main module  110 . 
     In block  107 , the filtered seabed resources are transferred to the storage module  114  in the main module  110  through an interface between the filtering module  112  and the storage module  114 . 
     In block  108 , seabed resources stored in the storage module  114  is transferred to a thruster assisted Vertical Transport System (VTS)  140 . 
     The VTS  140  is launched from the surface vessel  10  and hovers a predetermined location near the main module  110 . The VTS  140  is engaged with the main module  110  such that the seabed resources can be transferred from the main module  110  to the VTS  140 . 
     In one embodiment, the VTS  140  is launched from a side of the surface vessel  10  using an A-shaped frame by a launching rope. When the VTS  140  reaches vicinity of the main module  110 , the VTS  140  communicates with the main module  110  by means of transponders and sensors to initiate transfer of seabed resource from the main module  110  to the VTS  140 . 
     In block  109 , after the container  140   b  is full or at least partially filled with seabed resources, the transfer of seabed resources is stopped and the connection between the VTS  140  and the main module  110  is disengaged or released. 
     In block  110 , the VTS  140  is lifted up to the surface vessel  10 , e.g. by a winch, such that the seabed resources can be transferred to the surface vessel  10 . 
     In block  111 , the collecting devices  120  are withdrawn/retracted to the main module  110 , and reattached to the main module  110 . At this time, apparatus  100  is in a retracted position wherein the whole apparatus  100  is arranged in an unused or non-operational state and returned to the surface vessel  10 . 
     As described above, in the first embodiment, each collecting device  120  is communicably connected to the main module  110  by the a hybrid flow hose  121 , while, in some other embodiments, each of the collecting device may be remotely controlled by the main module in a wireless manner as shown in  FIGS.  2 A to  2 C . 
       FIG.  2 A  is a perspective view of an apparatus  200  for collecting seabed resources when the apparatus  200  is being lowered from a surface vessel  20  according to a second embodiment of the invention.  FIG.  2 B  is a perspective view of the apparatus  200  when it is in use.  FIG.  2 C  is a bottom perspective view of the apparatus  200  when it is in use. As shown in  FIG.  2 C , similar to the first embodiment, in this second embodiment, both the main module  210  and the collecting devices  220  attached thereto are positioned at a predetermined height above the seabed when the collecting devices  220  are used for seabed resources collection. 
     In the second embodiment as shown in  FIG.  2 B , unlike the first embodiment, when the collecting devices  220  are released from the main module  210 , there is no physical connection between the collecting devices  220  and the main module  210 . Thus, the power and resource transfer between the collecting devices  220  and the main module  210  cannot be realized once the collecting devices are released from the main module  210 . 
     However, the information/data communication between the main module  210  and the collecting devices  220  can still be performed in a wireless manner (sonar based communication), e.g. by a sensor suit provided on each collecting device  220 . That is to say, after being released from the main module  110 , each of the collecting devices  220  is configured to collect information relating to the characteristics of the seabed and transmit the collected information to the main module  210  in a wireless manner. Accordingly, the main module  210  is configured to determine the mining path for each of the collecting devices  220  based on the received information, control each of the collecting devices  220  to collect seabed resources along the determined mining path. 
     As there is no physical connection between the collecting devices  220  and the main module  210 , each collecting device  220  is configured to store the collected seabed resources in a storage module  220   d  therein and return to the main module  220  once the storage module  220   d  is at least partially filled with seabed resources. Accordingly, the main module  210  is further configured to control the transfer of the seabed resources stored in the collecting device  220  from the collecting device  220  to the main module  210  after the collecting device  220  is reattached to the main module  210 . 
     In a third embodiment of the invention, unlike the first and the second embodiments, the apparatus for collecting seabed resources is launched from a surface vessel and landed on the seabed. 
       FIG.  3 A  shows a top view of an apparatus  300  for collecting seabed resources when the apparatus  300  is in an un-used state according to the third embodiment of the invention. Referring to  FIG.  3 B , the apparatus  300  includes a main module  310  and six seabed resources collecting devices  320 .  FIG.  3 B  shows a perspective view of the apparatus  300  when it is in use according to the third embodiment. 
     As shown in  FIG.  3 A , each of the collecting devices  320  is releasably attached to the main module  310  when the collecting devices  320  are not in use, while when the collecting devices  320  are released from the main module  310 , each of the collecting devices  320  is movably and communicably connected to the main module  310  by a connecting cord  321 , which is a hybrid flow hose for power transfer, data communication and resource transfer between the collecting device  320  and the main module  310 . 
     As shown in  FIG.  3 B , the hybrid flow hoses  321  connect the individual collecting devices  320  to a pump assembly  315  which is configured to provide suction force for collecting seabed resources from the seabed to the collecting devices  320  and to provide force for transferring collected seabed resources from the collecting devices  320  to the main module  310 . In this embodiment, the pump assembly  315  includes six pumps which are respectively connected to the six collecting devices  320  by the hybrid flow hoses  321 . The hybrid flow hoses  321  respectively connect the six collecting devices  320  to the main module  310  to facilitate information/data and resource transfer between the main module  110  and each of the collecting devices  120  connected thereto. 
     The main module  310  may be connected to the surface vessel  30  and configured to be remotely controlled by a surface vessel  30 . The main module  310  includes a control module (not shown in the Figures) which is configured to determine a mining path for each of the collecting devices  320  based on characteristics of the seabed, and to control the collecting devices  320  to collect seabed resources along the determined mining path and control transfer of the seabed resources from the collecting devices  320  to the surface vessel  30 . Each of the collecting devices  320  is configured to be released from the main module  310  after the apparatus  300  is launched and landed on the seabed, and to collect seabed resources along the mining path determined by the main module  310  after being released from the main module  310 . 
     In embodiments of the invention, characteristics of the relevant seabed may include bathymetry, geographical features of the relevant seabed, intensity distribution and volume of seabed resources on the relevant seabed, and soil strength of the relevant seabed, etc. 
     To more effectively and accurately determine the mining path for each of the collection devices  320 , in some embodiments of the invention, each of the collecting devices  320  is provided with at least one sensor or other scanning device for collecting/gathering information relating to characteristics of the relevant seabed and the main module  310  is further configured to receive the information collected by each collecting device  320  and determine the mining path for each collecting device  320  based on the received information. 
       FIG.  3 C  shows a side perspective view of the apparatus  300  for collecting seabed resources. As shown in  FIG.  3 C , to at least partially remove sand particles and/or slurry from the collected seabed resources, in some embodiments of the invention, the main module  310  may further include a filtering module  312 . The filtering module  312  receives the resource along with the sand and slurry from the collecting devices  320  through the pump assembly  315  and the hoses  313 . 
     Referring to  FIGS.  3 B and  3 C , to temporarily store filtered seabed resources produced by the filtering module  312 , in some embodiments of the invention, the main module  310  may further include a storage module  314 . The storage module  314  is connected to the pump assembly  315  by a connecting hose. The pump assembly  315  is arranged to transfer the temporarily stored seabed resources away from the storage module  314 , e.g. to a container located outside the main module  310 . 
     Different types of filtering modules  312  may be interchangeably used in the apparatus  300 . In some embodiments of the invention, the filtering module  312  may include at least one input/feed channel arranged to allow the collected seabed resources enter the filtering module  312 ; a filter arranged to at least partially remove the sand particles and/or slurry from the collected seabed resources; at least one output/filtrate channel arranged to allow the filtered seabed resources to be transported out of the filtering module  312 , e.g. to the storage module  314 ; and at least one waste discharge channel arranged to discharge the sand particles and/or slurry from the main module  310 . 
       FIGS.  4 A to  4 C  respectively provide three different types of filtering modules which can be used in the apparatus  300  either alone or in any combination thereof, i.e. each of the three filtering modules can work as a stand-alone or in conjunction with at least one of the other filtering modules, e.g. the three filtering module may work together in series i.e. one after another, in the apparatus  300 . It should be noted that the three types of filtering modules can also be used individually or in any combination in the apparatus  100 / 200  in the first/second embodiments. 
     In the first type of filtering module  312  shown in  FIG.  4 A , the at least one input/feed channel includes an inlet  1   a  located at/near the bottom of the main module  310 . The filter includes a centrifugal system  2   a  having a chamber defined by a wall with mesh filters. The centrifugal system  2   a  is arranged to drive sand particles and/or slurry out of the chamber through the mesh filters. The sand particles and/or slurry are to be discharged from the filtering module  312  through at least one waste discharge channel. In this example, the at least one waste discharge channel includes two outlets  4   a  located at bottom of the main module  310 . The filtered seabed resources which remained in the chamber are to be transported out of the filtering module  312  through at least one output channel to the storage module  314 . In this example, the at least one output/filtrate channel includes a connecting pipe  3   a  connecting the filtering module  312  to the storage module  314 . 
     In the second type of filtering module  312  shown in  FIG.  4 B , the at least one input/feed channel includes a plurality of inlet tubes  1   b  located at/near the top of the main module  310 . The filter includes a perforated structure  2   b  with a trapezoidal cross-section, e.g. bowl, arranged to separate the seabed resources from the sand particles and/or slurry. It is to be appreciated by a skilled person in the art that in other embodiments, the perforated structure  2   b  may have other shapes and structure, e.g. plate, as long as it can be used to receive the collected seabed resources and at least partially remove the sand particles and/or slurry from the seabed resources. The at least one output/filtrate channel includes a suction pipe  3   b  connecting the filtering module  312  to the storage module  314 . The filtered seabed resources are transported to the storage module  314  by a hydraulic suction mechanism through the suction pipe  3   b . The at least one waste discharge channel includes an outlet  4   b  located at/near bottom of the main module  310  and arranged to discharge the sand particles and/or slurry out of the main module  310  by a pump suction system. 
     In the third type of filtering module  312  shown in  FIG.  4 C , the at least one input/feed channel includes an inlet  1   c  located at/near the bottom of the main module  310 . The filter includes a jet sprinkler system  2   c  arranged to direct one or more streams of water to wash the sand particles and/or slurry off the seabed resources and allow the sand particles/slurry fall into at least one waste discharge channel. The at least one output/filtrate channel includes a suction pipe  3   c  connecting the filtering module  312  to the storage module  314 . The filtered seabed resources are transported to the storage module  314  by a hydraulic suction mechanism through the suction pipe  3   c . The at least one waste discharge channel includes two discharging pipes  4   c  located at/near bottom of the main module  310  and connecting to the jet sprinkler system  2   c  to allow the sand particles and/or slurry to be discharged out of the main module  310 . 
     To further improve efficiency of transferring seabed resources from the main module  310  to the surface vessel  30 , in some embodiments of the invention, the apparatus  300  may be further provided with a conveying system including at least one pair of seabed sitting frame  350  and container  380  (indicated in  FIG.  8    to  FIG.  10   ). 
     The seabed sitting frame  350  is configured to be launched from the surface vessel  30  and landed on the seabed, e.g. by an A-shaped frame using launching ropes  351  and  352  and guide rails. The container  380  is configured to be launched/lowered from the surface vessel  30  along a guide system formed by the seabed sitting frame  350  and the launching ropes  351  and  352  and positioned on the seabed sitting frame  350 . After the container  380  is positioned on the seabed sitting frame  350 , the container  380  is fluidly connected to the main module  310  and configured to receive seabed resources transferred from the main module  310  and be lifted up to the surface vessel  30  by a winch. 
     To efficiently control the transfer of the seabed resources from the main module to the container, the conveying system may further include an intervention Remotely Operated Vehicle (ROV)  330 . The intervention ROV  330  is configured to assist with launching and landing of the seabed sitting frame  350  onto the seabed, and control a connection between the container  380  and the main module  310 . 
     To assist with launching and landing of the seabed sitting frame  350  onto the seabed, the intervention ROV  330  may be configured to determine if there are obstacles or undulations on the seabed based on information relating to the characteristics of the seabed collected by at least one scanning device, to ensure the seabed sitting frame  350  is landed/sitting on a flat seabed. In addition, the ROV  330  may be further configured to determine a distance between the seabed sitting frame  350  and the main module  310 , and adjust the distance therebetween if the determined distance is smaller than a predetermined value. 
     To control the connection between the container  380  and the main module  310 , the intervention ROV  330  may be configured to enable a connection between the container  380  and the main module  310  to allow seabed resources to be transferred from the main module  310  to the container  380 , e.g. attach a connecting hose from the main module  310  to the container  380 . The intervention ROV  330  may be further configured to disable the connection between the container  380  and the main module  310  when the container  380  is filled up with seabed resources, e.g. detach the connecting hose from the container  380 . Optionally, the intervention ROV  330  may be configured to provide a signal to the main module  310  to trigger opening or closing of a valve at the connecting hose between the container  380  and the main module  310 . Thus, the main module  310  can control the transfer of the seabed resources from the main module  310  to the container  380 . 
     In some embodiments of the invention, the main module  310  may be further provided with a depth transducer which is configured to ensure that the main module  310  is to be launched on a flat seabed such that the main module  310  can be firmly secured to the seabed through activating some suction actuators. Specifically, the depth transducer may be configured to collect information with respect to the seabed bathymetry and determine if the seabed is sufficiently flat for landing of the main module  310 . 
     In some embodiments of the invention, the main module  310  may be further provided with a latching system which is configured to control release of the collecting devices  320  from the main module  110  after the apparatus  300  is launched; and further configured to reattach the collecting devices  320  to the main module  310  before the apparatus  300  is returned to the surface vessel  30 , i.e. after the process of seabed resources is completed and the apparatus  300  is to be returned back to the surface vessel  30 . In some embodiments, the latching system may be remotely actuated to release or reattach the collecting devices  320  to the main module  310 . In one example, the latching system may include a pneumatic or a hydraulic system. Specifically, the latching system may be configured to release the collecting devices  320  attached to the main module  310  such that the collecting device  320  can start to collect seabed resources, and reattach the collecting devices  320  to the main module  310  upon completion of the seabed resources collection. 
     Embodiments of the invention also provide a method for collecting seabed resources using the apparatus  300 . The method at least includes the following steps: the apparatus  300  is launched from a surface vessel  30  towards a seabed and remotely controlled by the surface vessel  30 ; the main module  310  determines a mining path for each of the plurality of collecting devices  320  based on characteristics of the seabed; each of collecting devices  320  is released from the main module  310  and starts to collect seabed resources along the mining path determined by the main module  310 ; and the main module  310  controls the collecting devices  320  to collect seabed resources along the determined mining paths and control transfer of the seabed resources from the collecting device  310  to the surface vessel  30 . 
       FIG.  5    is a flowchart illustrating a method of collecting seabed resources according to the third embodiment of the invention. 
     In block  501 , the apparatus  300  is launched, e.g. lowered, from a surface vessel  30  to the seabed. 
     In this embodiment, the whole apparatus  300  is lowered and positioned on the seabed.  FIG.  6 A  shows a process of launching the apparatus  300  from a surface vessel  30  to the seabed according to this embodiment of the invention. In one example, the apparatus  300  may be launched from a surface vessel  30  to the seabed by a launching rope using moonpool or sideway controlled launching method. In the moonpool controlled launching method, the apparatus  300  is lowered to the seabed through a moon pool provided on the surface vessel. In the sideway controlled launching method, the apparatus  300  is launched from the side of the surface vessel  30  using an A-shaped frame  32  as shown in  FIG.  6 B . 
     In some embodiments of the invention, after the apparatus  300  is lowered to the seabed, the main module  310  is secured to the seabed through activating one or more actuators provided at the bottom of the main module  310 . To firmly secure the main module  310  to the seabed using the suction actuators, the main module  300  must be positioned on a relatively flat seabed, which may be realized by using a depth transducer provided on the main module  310 . 
     In some embodiments, the launching rope is a strong fibre or steel rope with sockets for supporting umbilical and power cables. The umbilical and power cables provide power and communication transfer from the surface vessel  30  to the main module  310 . 
     In block  502 , after the apparatus  300  is secured or fixed on the seabed, at least one intervention Remotely Operated Vehicle (ROV)  330  is released from the main module  310  of the apparatus  300 . 
     Each intervention ROV  330  is used to assist with launching and landing of a seabed sitting frame  350  which is provided for positioning a container  380 . 
       FIG.  7    shows a connection between an intervention ROV  330  and the main module  310  after the intervention ROV  330  is launched from the main module  310 . As shown in  FIG.  7   , in this example, the intervention ROV  330  is connected to the main module  310  by an umbilical  331 . In addition, the intervention ROV  330  also carries a second connecting hose/umbilical  332  which is connected to the main module  310  and attaches the connecting hose  332  to the container  380  to allow seabed resources to be transferred from the main module  310  to the container  380  (as shown in  FIG.  10   ). 
     In block  503 , at least one seabed sitting frame  350  is launched from the surface vessel  30  and landed on the seabed. 
       FIG.  8    shows two seabed sitting frames  350  launched from the surface vessel  30  and landed on the seabed according to the third embodiment of the invention. 
     In some embodiments, a seabed sitting frame  350  may be launched from the surface vessel  30  by an A-shaped frame using launching ropes  351  and  352  and guide rails and the seabed sitting frame  350  may reach or land on the seabed due to its own weight. 
     Each seabed sitting frame  350  is provided for positioning a container  380  located outside the main module  310 . The seabed sitting frame  350  together with the taut launching ropes  351  and  352  can provide a guide system between the surface vessel  30  to the seabed for controlled launching of a container  380 . 
     Each intervention ROV  330  may be equipped with scanning devices/sensors, e.g. altimeter sensors, transponders, sonar sensors and cameras, which are used to collect information relating to characteristics of the seabed. The ROV  330  is used to determine if there are obstacles or undulations on the seabed based on the collected information to ensure the seabed sitting frame  350  is landed/sitting on a flat seabed. The scanning devices, e.g. sonar, transponders and cameras, may be also used to determine the distance between the main module  310  and the seabed sitting frame  350 . In the event that the two bodies  310 ,  350  move too close to each other, the intervention ROV  330  is used to relocate, e.g. push/pull, the seabed sitting frame  350  to a desired location by using its manipulations and tools. Typically, the distance between the main module  310  and the seabed sitting frame  350  is 80 meters to 100 meters. Once the seabed sitting frame  350  sits on the seabed, the suction actuators are activated to firmly hold the seabed sitting frame  350  onto the seabed and at the same time, the launching ropes  351  and  352  are made taut and kept under constant tension, e.g. by using winches on the surface vessel  30 . 
     It is to be appreciated by a skilled person in the art that more than one seabed sitting frame may be provided in some embodiments. 
     In block  504 , at least one container  380  is launched from the surface vessel  30  and respectively positioned on a seabed sitting frame  350 . Each intervention ROV  330  connects a container  380  to the main module  310  through a connecting hose/umbilical  332 . 
       FIG.  9    shows two containers  380  which are launched and respectively positioned on/at two seabed sitting frames  350  according to the third embodiment of the invention.  FIG.  10    shows one container  380  is connected to the main module  310  through a connecting hose  332  which is carried by the intervention ROV  330 . As shown in  FIG.  10   , in this example, two seabed sitting frames  350  are provided to respectively position two separate containers  380 . Accordingly, two intervention ROV  330  are provided to respectively assist with launching and landing of the two separate seabed sitting frames  350  and control connection between the main module  310  and the two separate containers  380 . 
     Each container  380  has permanent ballast and thereby can reach the seabed using its own weight. As shown in  FIG.  9   , the launching control and recovery of the container  380  is performed by means of a launching rope  381 . Each container  380  may use the taut launching ropes  351  and  352  of a seabed sitting frame  350  as a guide system to reach the seabed. With the guide system provided by the seabed sitting frame  350 , the container  380  can reach on the seabed at a designated location. In absence of this guide system, drag forces due to the seawater current will cause drifting of the container  380  to a far location, and thereby impeding the mineral transfer operation. 
     Alternatively, in some embodiments of the invention, each seabed sitting frame  350  may be replaced with a self-propulsion system, e.g. water jet propulsion or thrusters or propellers, which is provided at the container  380  to resist the drag forces due to the seawater current. 
     In block  505 , the collecting devices  320  are released from the main module  310  and respectively deployed spaced apart at various positions away from the main module  310 . 
     As shown in  FIG.  9   , after the two containers  380  are respectively positioned on the seabed sitting frames  350 , the collecting devices  320  are released from the main module  310  and respectively located at positions spaced apart away from the main module  310 . 
     In block  506 , each of the collecting devices  320  is controlled by the main module  310  to collect seabed resources along the mining path which has been determined by the main module  310  based on characteristics of the seabed. The collected resources are subsequently transferred to the main module  310 . 
     In one example, the collection devices  320  may collect seabed resources by hydraulic suction which is provided by the pump assembly  315  provided in the main module  310 . Also, using the pump assembly  315 , the collected seabed resources are transferred to the main module  310 . 
     In one example, the method may further include: each of the collecting device  320  collects information relating to characteristics of the seabed by using at least one scanning device, e.g. sensor, and sends the collected information to the main module  310 ; and the main module  310  determines a mining path for each collecting device  320  based on the received information. 
     In block  507 , the main module  310  uses a filtering module  312  to at least partially remove the sand particles and/or slurry from the seabed resources. 
     In block  508 , the filtered seabed resources are temporarily stored in the storage module  314  in the main module  310 . 
     As mentioned above, the filtering module  312  may be any type of filtering module which can be used in the apparatus  300  to at least partially remove the sand particles and/or slurry from the seabed resources, for example, the filtering module  312  shown in any of  FIGS.  4 A to  4 C . 
     In block  509 , the seabed resources stored in the storage module  314  are transferred to a container  380  through a connecting hose/umbilical  332  which is connected from the storage module  314  to the container  380  by the intervention ROV  330 . 
     In one example, the intervention ROV  330  sends a signal to the main module  310  to trigger opening of a valve of/at the connecting hose such that the seabed resources can be transferred to the container  380  from the main module  310 . 
     The pump assembly  315  provided in the main module  310  may be used to transfer the seabed resources from the storage module  314  to the container  380 . 
     In block  510 , after the container  380  is full or at least partially filled with seabed resources, the transfer of seabed resources from the main module  310  to the container  380  is stopped and the connecting hose/umbilical  332  is detached from the container  380  by the intervention ROV  330 . 
     In one example, when the container  380  is full or at least partially filled with seabed resources, the intervention ROV  330  sends a signal to the main module  310  to trigger closing of a valve at the connecting hose/umbilical between the container  380  and the main module  310 . 
     In block  511 , the filled container  380  is lifted up by winches onto the surface vessel  30  and the seabed resources in the container  380  are subsequently transferred to a storage unit on/at the surface vessel  30 . In one example, the seabed resources in the container  380  may be sucked by a hose and dumped to a storage bay on the surface vessel  30 . 
     If more than one container  380  are launched and positioned on the seabed, then the steps  509  to  511  will be repeated for the remaining containers  380 . 
     In block  512 , after the collection process (including transfer to container  380 ) completes, the collecting devices  320  and the intervention ROV  330  are retracted and reattached to the main module  310 . The whole apparatus  300  in retracted position, including the seabed sitting frame  350 , is then returned to the surface vessel  30  either sequentially or simultaneously. 
     It should be noted that the method described above is only for illustrative purpose, and not used to limit the scope of the invention. The sequence of the steps for launching the main module, the at least one intervention ROV, the at least one seabed sitting frame, the at least one container and the collecting devices may be modified in other embodiments of the invention. For example, the steps  504  and  505  may be carried out at the same time as long as when the collected seabed resources need to be transferred from the main module  310  to the container  380 , the installation of the container  380  and connection between the container  380  and the main module  310  have been completed. 
     With the apparatuses and methods for collecting seabed resources disclosed above, a plurality of collecting devices can be controlled by a main module to collect seabed resources simultaneously along the mining paths determined by the main module. Moreover, as the main module is configured to control transfer of the seabed resources from the collecting devices to the main module and/or from the main module to the container, the efficiency of transfer of the seabed resources will be significantly improved. Further, at least one container located on the seabed may be used to temporarily store the collected seabed resources before transferring the seabed resources to the surface vessel to further increase the efficiency of transfer of the seabed resources. 
     It is to be understood that the embodiments and features described above should be considered exemplary and not restrictive. Many other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the invention. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. Furthermore, certain terminology has been used for the purposes of descriptive clarity, and not to limit the disclosed embodiments of the invention.