CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No.

61/883,519 filed September 27, 2013, the contents of which is hereby incorporated in its entirety.

FIELD OF TECHNOLOGY

[0002] A winch system for transferring loads between a mother vessel and a daughter vessel, and more particularly, a multi-body motion compensation system that, prior to a payload being attached to a winch hook, compensates for the relative motions between the two vessels.

BACKGROUND

[0003] Oil platform supply vessels transport cargo and equipment to and from off-shore oil platforms and they serve an important function in the supply pipeline for those that work in the shipping and oil platform industries. In order to facilitate the transfer of cargo to and from the platform, a crane can be located on the platform and a crane operator manually operates the crane in concert with deck crews that can be located on both the platform and on the supply vessel. The crane operator may communicate with the deck crews by using telecommunication devices so as to aid in the safe and efficient transfer of payloads between the platform and the supply vessel.

[0004] The crane operator controls a winch drum which reels in and out a lifting hook that is in turn connected to the winch cable. The deck crew on the supply vessel in turn connects the hook to the payload. Prior to the winch hook being connected to the payload, the distance between the hook and the deck of the supply vessel changes as the sea heaves, pitches and rolls, thus creating a significant challenge for the crane operator to maintain the lifting hook at a steady position. This also creates a challenge for the deck crew on the supply vessel to maintain control of the lifting lines and the lifting hook prior to it being connected to the payload. [0005] Typically a payload is only transferred to and from a supply vessel when the sea state is relatively calm. The calm seas allow minimal relative motion between the lifting hook and the deck of the supply vessel, and this decreased motion allows the deck crews to safely handle the lifting lines and the associated lifting hook. The crane operator, often located on the platform, continuously monitors the location of the supply vessel as the lifting hook transfers goods to and from the supply vessel. As long as the sea state remains relatively calm, the crane operator generally can safely maneuver the lifting hook and cargo.

[0006] As the sea state increases the crane operator's job of safely moving cargo to and from the supply vessel likewise becomes increasingly more difficult. This is due, in part, because as the sea state increases, so does the relative motion between the lifting hook and the deck crews on the supply vessel. This in turn may cause an increase in potential safety hazards to the deck crew. Thus, during heavy seas supply vessels may not even attempt to transfer cargo and instead may stay in port or out to sea to wait for more desirable sea conditions. As such there is a direct correlation between the number of days at sea when cargo can be transferred between moving bodies and the state of the sea. The calmer the seas the greater the number of days supply vessels can transfer cargo and serve the needs of those on the platform. Increasing the number of days each year when cargo may be transferred between vessels could add efficiencies to the shipping and oil platform industries.

[0007] Transferring cargo from a supply vessel to another moving vessel, for example a larger ship, likewise can be challenging under heavy seas. Under these circumstances, the supply vessel is a moving body and the ship is a moving body, thus creating two independent moving bodies. Under such circumstances, transferring cargo between two moving bodies becomes increasingly difficult, particularly as the sea state increases. This is because the relative motion between the lifting hook and the deck crew increases. Under such conditions the safety challenges increase and often conditions deteriorate to the point where cargo may not be transferred until calmer conditions return.

[0008] It would be desirable to provide a multi-body motion compensation system for marine applications that is able to compensate for the vertical motion which is caused from the heave, pitch and roll motions of one or more bodies while they are at sea. It would also be desirable to provide an improved motion compensation system for use in connection with a floating oil platform that is operable to automatically compensate, without any input from a winch operator, for the relative motion between the two moving bodies, prior to the lifting hook being connected to a payload.

[0009] It would also be helpful to provide an improved winch and associate control logic for increasing the smooth transition of objects between two moving bodies. Such a winch system could maintain the positioning of the winch hook relative to the deck of a supply vessel, and improve the safety of those working on the deck of a watercraft. Other improvements are contemplated by this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] While the claims are not limited to a specific illustration, an appreciation of the various aspects is best gained through a discussion of various examples thereof. Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent the illustrations, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an example. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricted to the precise form and configuration shown in the drawings and disclosed in the following detailed description. Exemplary illustrations are described in detail by referring to the drawings as follows:

[0011] FIG. 1 illustrates a side schematic view of a winch system secured to a first moving body, having a lifting hook that is about to be connected to a payload located on a supply vessel (daughter vessel) or about to be connected directly to the daughter vessel;

[0012] FIG. 2 illustrates a schematic diagram of a deck worker holding on to a hook while standing on the deck of a supply vessel, while the system maintains the distance (d) between the hook and the deck;

[0013] FIG. 3A illustrates a schematic view of an oil platform and a supply vessel and the effect of the heaving motion that is generated by the sea;

[0014] FIG. 3B illustrates a schematic view of an oil platform and a supply vessel and effect of the pitching motion that is generated by the sea; [0015] FIG. 3C illustrates schematic view of an oil platform and an end view of a supply vessel, showing the supply vessel rolling due to the motion of the sea;

[0016] FIG. 4 illustrates an alternative embodiment of a motion compensation system employing numerous sensors on both the platform and the supply vessel;

[0017] FIG. 5 illustrates a schematic diagram of a smart winch having an encoder, motor, drive train, drum and a brake;

[0018] FIG. 6 illustrates a block diagram of the control logic for operating a winch that can be used in the motion compensation system; and

[0019] FIG. 7 illustrates a block diagram of one embodiment of the steps for operating a motion compensation system.

DETAILED DESCRIPTION

[0020] A motion compensation system may be employed in marine applications for detecting motion between a platform (mother) and a supply (daughter) vessel. The system may employ a laser-type sensor that is secured to the platform and is in communication with a computer having at least a processor, a storage medium, and software for operating a control algorithm. The computer communicates with the sensor and operates a power winch which in turn has a cable and a lifting hook for attaching to a payload on moving body such as a supply vessel. The lifting hook could also be connected on the daughter vessel which would facilitate the recovery of the smaller vessel on board the mother vessel. The system, in real-time, is operable to automatically monitor the position of the lifting hook relative to the deck of a supply vessel and strive to maintain the distance therebetween, even during difficult sea conditions. The system is also operable to automatically compensate for motions between the platform and the supply vessel, without operator intervention.

[0021] In some situations a daughter vessel will be recovered onboard the mother vessel. The daughter vessel could be a manned or unmanned vehicle and could be a surface or even a subsurface vehicle. The processes, circumstances and technology described throughout this document are also applicable to recovery of the daughter vessel onto a mother vessel. [0022] Other aspects of the disclosure may provide sensors being provided at various locations on the platform, crane and/or supply vessel, which in turn may communicate directly with the computer so as to provide multiple points of real-time data. Such data may be utilized to provide redundant safety systems so as to aid in safe operation and to accommodate the harsh sea environment. Moreover the daughter vessel itself could be considered the cargo being brought on board the mother ship via this lifting system.

[0023] With reference to FIG. 1, a motion compensation system 10 is presented and includes a computer 12, a power winch 14 and at least one sensor 16 that communicates via telemetry 18, or by other communication means. A platform 20 provides a foundation in which the winch 14 is mounted via a pivotal or fixed base 22. A boom 24 may be pivotally connected 26 to a base 28 which is in turn connected to the deck 30 of the platform 20. A pulley 32 routes a winch cable 34 which in turn is wrapped around a drum 36 of the power winch 14. An opposing end 38 of the cable 34 has a hook 40 secured thereto, and the hook 40 is operable to be connected to a cargo cable 42 of a supply vessel 44. The cargo cable 42 may be connected to a payload 46 that could be positioned on the deck 48 of the supply vessel 44. The hook 40 may also be referred to as a connector, shackle, end effector, or the like.

[0024] The supply vessel 44 moves relative to the waves 50 a function of the sea state 52 ebbs and flows. The waves 50 cause the supply vessel 44 to heave, pitch and roll. This in turn causes the payload 46 to move relative to the deck 30 of the platform 20. Likewise, the cargo cable 42 moves in part relative to the deck 48 of the supply vessel 44 which makes it difficult for a deckhand 60 to connect the cargo cable 42 to the hook 40. During a turbulent sea state connecting the hook 40 to the cargo cable 42 becomes increasingly difficult, a problem the present disclosure addresses.

[0025] If the platform 20 is a floating type platform, then the platform 20 and the hook 40 also move due to the waves 50. This causes a relative motion between the hook 40 and the cargo cable 42 and its associated payload 46. The supply vessel 44 often translates and rotates on the X, Y and Z axes and is forever changing due to the nature of the ocean waves 50. This causes a distance "d" between the deck 48 and the hook 40 to change, if not controlled by the motion compensation system 10. The motion compensation system 10 is operable to, inter alia, control the hook 40 in the Z axis 54 so as to maintain the distance "d" between the hook 40 and the deck 48. The system is able to compensate for changes in the Z direction which can be caused by linear translations along the Z axis in addition to rotations about the X and Y axis.

[0026] A control system 56 includes the computer 12, the sensor 16 and the winch 14 working in concert to let out or reel in the cable 34. The computer 12 includes a processor, storage medium, executable software -which may include a control algorithm-and an output signal for controlling the winch 14. A secondary controller may be used with the winch to facilitate its operation and the secondary controller would be in communication with the computer. The computer 12 receives signals from at least one sensor 16, and it will be appreciated that the computer 12 may receive signals from other sensors throughout out the system 10. For example, sensors may be located at various locations on the platform 20, the boom 24, the hook 40, and/or the vessel 44. The sensor 16 is shown mounted to the boom 24, however, it will be appreciated that the sensor 16 may be mounted to other structures on the platform 20. The sensor 16 generates a motion sensor field 58 that is operable to sense the supply vessel 44. In particular, the sensor 16 could be a LIDAR (Light Detecting and Ranging) laser type sensor that is operable to determine the motion of the supply vessel 44. Once the motion of the supply vessel 44 is determined, the computer 12 calculates how much cable 34 needs to be wound in or out of the winch 14 prior to connection of a payload 46 to the hook 40. A benefit of this system 10 is that a deckhand 60 standing on the deck 48 of the supply vessel 44 would not perceive any change in the position of the hook 40 relative to his viewpoint. This allows the deck crew 60 to easily and safely connect the hook 40 to the payload 46 via the cargo cable 42. The control algorithm that forms a part of the computer code for the computer 12 accounts for the electro-mechanical delays that could be found in the winch 14. An encoder can be provided that counts the rotational movement of the drum member of the winch. The signals from the encoder are processed by the computer 12 to aid in the accurate reeling of the cable 34.

[0027] FIG. 2 illustrates a schematic diagram of a deck crew member 60 depicted standing on a deck 48 under three separate scenarios 62, 64 and 66, which depict different instances in which a wave 50 could influence a supply vessel 44. The first scenario 62 depicts a moment when the wave 50 begins to crest. The hook 40 is maintained a distance "d" from the top service of the deck 48. The distance d is determined by the system at the outset and prior to the crane operator picking up any payload. The process of determining d is set forth below. [0028] The system 10 monitors the position of the deck 48 relative to the hook 40 and automatically adjusts the position of the hook 40 and strives to maintain a set point having a value of "d". Such arrangement allows the deck hand 60 to more easily control or maneuver the hook 40 as he connects the hook 40 to a payload 46. The system 10 is operable to adjust the location of the hook 40 in the Z axis so as to account for the sea heaving, rolling and pitching this compensates for translations along the Z axis in addition to rotations about the X and Y axis. Thus, a dynamic real time automatic hook 40 positioning system 10 is provided that aids in positioning the hook 40 prior to being attached to the payload.

[0029] As the wave begins to crest as shown in the second scenario 64, the deck 48 will rise upwardly 68 as a result of the seas buoyancy forces imparting motion upon the supply vessel 44. In order to maintain the set point distance "d" the motion compensation system 10 will cause a signal to be sent to the power winch 14, which in turn reels in the cable 38 around the drum 36. Telemetry 69 may be used in connection with the hook 40 to form a smart hook that is operable to communicate with the sensor 16, or some other device. As the wave 50 recedes in the direction of arrow 70, the deck 48 may move negatively in the Z axis. When such a condition is sensed, the computer 12 sends a signal to the power winch 14 instructing it to let out cable 38 in the direction of arrow 70. The amount of cable 38 let out is the amount necessary to maintain the distance d. The winch 14 continues this process an infinite number of times per second so as to maintain the constant distance d.

[0030] FIG. 3A illustrates a side view of a supply vessel 44 relative to a platform 20 with the vessel shown in a first position 74 in solid lines, and the same vessel shown in a second position 76. Likewise, the hook 40 is shown in solid lines relative to the deck 48 as the vessel 44 is depicted in its first position 74. By contrast, when the vessel 44 is positioned to its second position 76, the hook 40 is shown in a reeled in position and is represented by the phantom hook 40'. As the vessel 44 heaves commensurate with the sea 52, it oscillates between a variety of positions, including those shown in the positions 74 and 76. The cable 38 moves in the Z axis 54 as shown by the arrow 78. Likewise, the vessel 44 moves in the direction of the Z axis 54, along a path that is shown by arrow 80.

[0031] The sensor 16 communicates with the computer 12 which in turn provides signals to the winch 14. The sensor 16 continually monitors the positioning of the vessel 44 and the hook 40. The sensor 16 is operable to sense the vessel 44 as the vessel heaves, rolls and pitches and it generates signals (data) several thousand times per second that pinpoints the location of the deck, both in the X, Y and Z axes. The sensor 16 can also be used to locate the position of the hook 40; however, an encoder 126 can be used to pinpoint the location of the hook. The computer 12 continuously the monitors the signals (which are signal data) that are generated by sensors 16 and 126 and then compares the signal data to a set point to calculate any variances. The winch in turn receives a winch signal instruction from the computer 12 for adjusting the hook 40 so as to eliminate any such variances.

[0032] FIG. 3B illustrates a motion compensation system 10 where the vessel is shown in a first position 74 and then advance as it pitches to a second position 76 that is shown in phantom (a rotation on the Y axis). However, this time the vessel 44 is shown pitching in the direction of arrows 82 whereby the bow and the stern are subjected to a pitching moment. The pitching moment is as a direct result of the seas 52 pitching along a vector 86 under the influence of sea waves 50. The sensor 16 senses the vessel 44 pitching movement and communicates data signals to the computer 12 about such an event. When the vessel 44 pitches, the payload 46 moves along the Z axis 54. As this occurs, the hook 40 moves to an alternate position 40' so as to maintain distance "d" relative to the deck 48 in the Z directions as the vessel pitches. Thus, the system 10 is operable to automatically compensate the hook 40 be relocated along a signal axis but accounts for motion on three other axis, this compensation is nearly impossible for a crane operator to accomplish when the vessel pitches.

[0033] FIG. 3C illustrates a schematic diagram of a motion compensation system 10 having a platform 20 with the stern end of a vessel 44 positioned relative thereto. The vessel is shown in a first position 74 and then advances to a second position 76 (shown in phantom). The vessel 44 rolls commensurate with the rolling action of the sea 52. The vessel 44 moves along the Z axis 54 and also rotates on the X axis 88 along a vector 90. The vector 90 depicts a potential rolling vector the sea could induce upon a vessel. As the vessel 44 rolls in the direction of arrows 92, the hook 40 is moved in the direction of arrow 78 in order to maintain the distance "d" at a fixed location. The sensor 16 is operable to sense the amount of roll of the vessel 44 and in turn communicates data to the computer 12 which in turn sends a signal to the winch 14 so as to let out or reel in the appropriate amount of cable 34. Thus, the system 10 is operable to adjust the positioning of the hook 40 along the Z axis so as to maintain the hook 40 in a relatively steady state relative to the deck of a supply vessel. [0034] FIG. 4 illustrates an alternative motion compensation system 100 that includes a power winch 14, a computer 12, a sensor 16 and a subject or a target, such as a supply vessel 44. The winch includes a boom 24 with its associated cable 34 and hook 40. The winch 14 is powered by a hydraulic power unit 102 which includes a hydraulic pump, having a hydraulic fluid supply for delivering pressurized fluid power via a line 104 to the winch 14. The hydraulic power unit 102 may be secured to the deck of a platform 20 and it will be appreciated that it may be located remotely. The winch 14 may be, in any of the

embodiments herein, to be an electric winch as opposed to a hydraulically operated winch.

[0035] The alternative motion compensation system 100 may include a plurality of sensors 106 that may be located on the boom 24, the base 108 of the platform 20, and on the supply vessel 44. The sensors 106 may be laser, infrared or radar, and may generate one or more fields 110. One of the fields may locate the hook 40 and another field may locate the deck 48 of the supply vessel 44. Having multiple sensors 16 and 106, may provide for redundancy and checking within the system 100 and could help improve safety of the system 100.

[0036] The hook 40 may be a smart hook in that it may include a gyro meter and telemetry 112. The smart hook 40 may generate positioning signals of its location on a 3-D axis relative to the earth that in turn are communicated with the computer 12. The computer may receive such signals via telemetry which may identify the precise instantaneous location of the hook relative to the earth, the platform 20, and the vessel 44. This data could be used to help identify and control the positioning of the hook 40 relative to the deck 48 of the supply vessel 44. The computer 12 processes this data which in turn provides signals to the power winch 14 and adjusts the positioning of the hook 40 so as to maintain the positioning "d".

[0037] FIG. 5 illustrates an example of a power winch 14 that may be used with the motion compensation system 10 or 100. The power winch 14 includes a cylindrically shaped drum 120 that has a drive train 122, a motor 124 and an encoder 126 for counting the rotations of the drum 120. A brake 128 could allow the system 10 to maintain a constant tension on the cable 34. The motor 124 may be a hydraulically activated motor, or it can be an electric motor that in turn imparts motion to the drive train 122 and connected drum 120.

[0038] FIG. 6 illustrates a schematic diagram of a control algorithm 130 that may be used with the compensation systems 10 and/or 100. The control algorithm 130 receives input from a laser sensor 16 that continuously senses information about a first moving body 132. The first moving body could be a floating or fixed oil platform, a ship, or some other structure. The computer 12 with the aid of a sensor 16 identifies a second moving body 134. The second moving body can be a supply vessel 44 or some other structure that could be floating at sea. The computer 12 then computes the kinematics of a second moving body relative to the end effector of a crane 136. The end effector of a crane could be the end of the boom 24. In this example, the computer 12 may compute the kinematics of the vessel 44 relative to the end of the boom 24. The computer 12 then determines the set point of the controller 138 which is an exemplary data point identifying the position of the hook 40 relative to the end point of the boom 24 through the aid of an encoder 126. Alternatively, the set point could be an exemplary data point of the distance "d" in which the hook 40 is positioned relative to the deck 48 of the vessel 44. Either way, the set point is a data point which the controller of the computer 12 uses as a base point for determining and aiding in the positioning of the hook.

[0039] Once the set point is determined 138, a signal 140 is sent to a winch controller 142. The winch controller 142 provides signals 144 to the winch system 14 (See FIG. 5). The winch system 14 controls the cable reeling 146 which in turn determines the position at set point "d" 148. As the winch system 14 reels the cable in and out, the encoder 126 counts the rotations of the drum 120. The encoder 126 sends signals 150 to the winch controller 142 thereby completing a closed-loop control system. A signal 152 may be sent from the hook 40 back to the computer/controller 12 and provide additional kinematics to the computer 12 with respect to the positioning of the hook 40. It will be appreciated that the control algorithm 130 may be modified to have more of fewer logic steps and such is considered within the scope of the present disclosure. The encoder 126 is used to help determine the end effect, i.e., position of the hook 40, which is used to then determine the set point d.

[0040] FIG. 7 illustrates an alternative motion compensation system 160 and a method of operating same. The system 160 includes a first moving body 162, a second moving body 164, a winch drum assembly 166, a laser sensor 168 and a control system 170. The winch drum assembly 166 includes a drum, a controller, a cable, an encoder and a hook member. The control system 170 includes a computer, a controller, computer storage, and an algorithm, such as a computer program.

[0041] The system 160 further includes the step of identifying the location of the second moving body 172. This can be accomplished by the laser sensor 168 creating a field, and the second moving body passing within that field and the sensor sensing same to create a signal that is in turn relayed to the control system 170. Once the signal is sent to the control system 170, the next step is computing the kinematics of the second moving body relative to the hook 174. Thereafter the computer determines the set point of the controller 176. The set point is calculated each time the system 160 operates to move a payload from one moving body to another moving body.

[0042] The system 160 further has a monitoring step 178 which is when the system 160 monitors the position of the hook relative to the second body and as the relative kinematics of bodies' change, the control system 170 responds to the difference between the set point and the measured amount of cable let out. By contrast, the control system could respond to the difference between the deck 48 and the hook which has been given the variable identifier "d".

[0043] The next step of operation for the system 160 is powering the winch to move the hook back to the set point 180. The system 160 then determines if the hook has been connected to the payload 182. If the hook has not been connected to the payload, then the system 160 repeats the loop 184 and reverts back to the step of identifying the second moving body 172. If, however, the hook has been connected to the payload, then the system 160 stops 186. At this point in time the winch operator may operate the winch and move the load to the deck of the first moving body, whereby the winch 14.

[0044] The motion compensation system 160 may include a control algorithm having variables for a first moving body, a second moving body, a winch, a hook, and ship motion sensors. The control algorithm operates on the operating system of a computer and works in tandem with the crane operator as he manually operates the crane. Accelerometers may provide input to the control algorithm to measure acceleration of the hook in/out which controls delivery of the hook in a contemplated safe and steady state. Sensing signals are input to the control algorithm via the sensor field to monitor and control the distance d between the hook and the deck of the delivery vessel as well as setting an initial Target "d" or set point variable.

[0045] The control algorithm continuously computes the kinematics of the second moving body relative to the hook and it senses the heave of the second moving body relative to the heave of the first moving body and determines a heave variable (this will be relative to the vertical component of the wave movement). The computer computes via the control algorithm a Compensating D and Accelerator V which is the distance/velocity variable the winch must operate (let out/retract) in order for the system to maintain the Target "d" at all times so that the relative motion between the two bodies automatically remains constant without operator intervention. The system continuously monitors the Target "d" and compares it to the Compensating D and automatically adjusts the hook via the power winch before the hook is tethered to the cargo. Once the hook is tethered to the cargo, a tension mode may operate to maintain tension on cable. The brake of the winch could be used to help maintain the tension and this too may be controlled by the control algorithm.

[0046] It will be appreciated that the aforementioned method and devices may be modified to have some components and steps removed, or may have additional components and steps added, all of which are deemed to be within the spirit of the present disclosure. Even though the present disclosure has been described in detail with reference to specific embodiments, it will be appreciated that the various modifications and changes can be made to these embodiments without departing from the scope of the present disclosure as set forth in the claims. The specification and the drawings are to be regarded as an illustrative thought instead of merely restrictive thought.