GB2633346A

GB2633346A - Method and system for stabilising a vessel against a stationary structure

Info

Publication number: GB2633346A
Application number: GB2313596.5A
Authority: GB
Inventors: Percy Iain; Ingouf Romain
Original assignee: Artemis Technologies Ltd
Current assignee: Artemis Technologies Ltd
Priority date: 2023-09-06
Filing date: 2023-09-06
Publication date: 2025-03-12
Also published as: US20250074555A1; EP4524015A1; GB202313596D0; WO2025052097A1

Abstract

A system 710 for stabilising a vessel (10, Fig 6) against a stationary structure (74, Fig 6) includes a sensor system 720, a processor, and a vessel control system 730. The processor is configured to determine a change in the position and/or motion of the waterborne vessel relative to the stationary structure based on sensor data, and to determine a minimum corrective force required to oppose the change. The minimum corrective force is then delivered by the vessel control system operable to stabilise the waterborne vessel relative to the stationary structure. A method for stabilising a vessel against a stationary structure is also disclosed.

Description

METHOD AND SYSTEM FOR STABILISING A VESSEL AGAINST A STATIONARY

STRUCTURE

FIELD OF INVENTION

The present invention relates to autonomously controlling a waterborne vessel, such as a yacht, sailboat or ship. In particular, the present invention relates to autonomously controlling a vessel in order to stabilise the vessel against a stationary structure while reducing emissions produced by the vessel during such manoeuvres.

BACKGROUND OF THE INVENTION

Waterborne vessels may be a single hull, often referred to as a mono hull, a catamaran (which has two hulls), or a trimaran (which has three hulls). In the case of multiple hulls, the hulls are held together by a single upper deck. The wider and longer the vessel, the more

stable the it is.

Waterborne vessels may be designed for non-recreational use, such as workboats for transportation of personnel or goods, and perform various operational manoeuvres during use. In particular, maritime operations involving the construction and maintenance of offshore assets (such as offshore windfarms, oil and gas fields, and aquaculture sites) require regular crew replacements and servicing by inspectors, technicians and the like.

These maritime operations tend to be handled offshore and so personnel are transported to the offshore assets either by boat or by helicopter. The use of helicopters is not always suitable or appropriate for transferring personnel to the offshore asset, and carries a degree of risk.

However, the use of boats to transfer personnel is also not without risk due to frequently rough sea states resulting in significant relative movement between the boat and the offshore asset.

Typically, this problem is addressed by using engagement mechanisms to secure the boat to a stationary structure. For example, prior art document GB2476858A discloses an apparatus comprising jaws that is attached to a floating craft, the jaws retaining a suitably sized part of the stationary structure when moved from an open position to a closed position to create a stabilising contact between the structure and the floating craft.

Alternatively, the problem may be addressed by abutting the bow of the vessel against part of the offshore asset, such as a ladder or pontoon, and driving the vessel with full throttle against the offshore asset in a so-called "bump and jump" operation. The thrust of the vessel produces a large friction coefficient between the vessel and the offshore asset that overcomes or significantly reduces the motion of the boat relative to the offshore asset caused by the sea state, tide or weather conditions. However, this approach requires high energy usage, resulting in increased fossil fuel usage and carbon emissions for conventional combustion-driven vessels, or greatly reduced operational range for electric-driven vessels. The approach also relies on the skills of the boat driver to keep the boat aligned relative to the offshore asset during personnel transfer in order to maintain safety.

There is therefore a need for an improved method of actively controlling a boat to avoid human error and reduce energy usage or emissions when transferring personnel and goods to and from an offshore asset.

SUMMARY OF THE INVENTION

The invention is defined by the claims to which reference should now be made. Preferred features are outlined in the dependent claims.

According to a first aspect of the invention there is provided a system for stabilising a waterborne vessel against a stationary structure, the system comprising a sensor system for providing sensor data, a processor configured to receive data from the sensor system, determine from the sensor data a change in the position and/or motion of the waterborne vessel relative to the stationary structure, and calculate a minimum corrective force required to oppose the change, and a vessel control system operable to deliver the minimum corrective force and to thereby oppose the change in the position and/or motion of the waterborne vessel relative to the stationary structure.

The present invention provides improvements in safety when transferring personnel and goods between a workboat and a stationary structure, such as an offshore asset.

It is to be appreciated that the system according to the first aspect of the present invention may be provided integrally as part of a new vessel during manufacture, or may be provided for retrofit to an existing vessel. In both cases, the vessels will then have all the advantages provided by the system. Such advantages include: * human-free optimised control of the vessel during transfer to the offshore asset, thereby avoiding human errors, improving the safety of the personnel and reducing damage to expensive equipment; * autonomously controlled positioning of the vessel within the water in response to real-time sensor data, enabling much faster response time than human pilots; * reducing human error from vessel skipper operations, thereby improving the safety of onboard personnel and equipment during operations at sea; * reducing energy consumption and associated emissions during marine operations to transfer crew or equipment between a vessel and an offshore asset where the power delivered by the engine is regulated to provide the minimum thrust required to stabilise the vessel against an offshore asset in dependence upon a real-time assessment of the local environment; and * for non-electric propulsion vessels, reduced fossil fuel usage and emissions during transfer to an offshore asset * for electric propulsion vessels, no fossil fuel usage during travel of the vessel and all power is provided in a carefully controlled manner from the battery system, particularly during transfer to an offshore asset.

Thus, the first aspect of the present invention provides a reduction in carbon emissions for conventionally powered vessels, extends the operating range of electrically powered vessels by reducing the energy requirements during transfers, and additionally increases the safety for the operating crew and personnel by reducing pilot involvement.

In some embodiments, the vessel control system comprises a propulsion system and a steering system. This advantageously enables the vessel control system to automatically configure the motion and position of the vessel.

In some embodiments, the propulsion system includes an engine, a gearbox and a propeller. Configuring each of these components with the vessel control system advantageously enables the motion and position of the vessel to be automatically controlled.

In some embodiments, the steering system comprises one or more control surfaces. Providing control surfaces, which may be configured by the vessel control system, advantageously enables the motion and position of the vessel to be automatically controlled.

Some embodiments further comprise a battery system in electrical communication with the vessel control system and operable to provide power to the propulsion system and/or steering system. This advantageously reduces carbon emissions and the use of fossil fuels in order to operate the vessel and the vessel control system.

In some embodiments, the waterborne vessel includes a hydrofoil having a plurality of adjustment members. Providing adjustment members, which may be configured by the vessel control system, advantageously enables the motion and position of the vessel to be automatically controlled.

In some embodiments, the processor is configured to determine the current vessel operating conditions, including one or more of a sea state, a wind state, and a tide state, based on the sensor data. This advantageously enables the vessel control system to automatically control the motion and position of the vessel in response to the local weather conditions.

In some embodiments, the sensor system includes one or more vessel position sensors and one or more vessel motion sensors. This advantageously enables the vessel control system to accurately manoeuvre the vessel relative to the stationary structure.

In some embodiments, the vessel position sensors includes one or more of a LIDAR, Ultrasonic distance sensor, GPS module, bow pressure sensor, or wind sensors. This advantageously enables the vessel control system to accurately manoeuvre the vessel relative to the stationary structure.

In some embodiments, the vessel motion sensors include an accelerometer or an inertia measurement unit (IMU). This advantageously enables the vessel control system to automatically configure the position and motion of the vessel in response to measured changes in vessel motion, such as when the vessel starts to slip off the stationary structure.

In some embodiments, the vessel control system is configured to deliver the minimum corrective force by adjusting the thrust delivered by a propulsion system to thereby urge a contact portion of the waterborne vessel against the stationary structure. This advantageously enables reduced energy usage and emissions when transferring crew and/or equipment between the vessel and the stationary structure.

In some embodiments, the contact portion of the vessel is a bow fender that includes a bow pressure sensor. This advantageously This advantageously facilitates determining whether the vessel is stabilised against the stationary structure, and enables the vessel to be stabilised against the stationary structure efficiently by ensuring the contact portion is in alignment with a stern-to-bow axis through which the propulsion system delivers a thrust force.

In some embodiments, the engine comprises a Motor Generator Unit (MGU). This advantageously provides reduced complexity and maintenance.

According to a second aspect of the invention there is provided a method of stabilising a waterborne vessel against a stationary structure, the method comprising a) receiving sensor data from a sensor system, b) determining, from the sensor data, a change in the position and/or motion of the waterborne vessel relative to the stationary structure, c) calculating a minimum corrective force required to oppose the change, d) adjusting the configuration of a vessel control system to deliver the minimum corrective force and to thereby oppose the change in the position and/or motion of the waterborne vessel relative to the stationary structure, and repeating steps a) to d).

The advantages associated with the second aspect of the invention are the same as those described above for the first aspect of the invention.

In some embodiments, adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting the thrust delivered by a propulsion system to thereby urge a contact portion of the waterborne vessel against the stationary structure. This advantageously stabilises the vessel against the stationary structure while reducing energy usage, carbon emissions and/or the use of fossil fuels.

In some embodiments, adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting one or more control surfaces of a steering system to deliver the minimum corrective force. This advantageously stabilises the vessel against the stationary structure while reducing energy usage, carbon emissions and/or the use of fossil fuels.

In some embodiments, adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting both a propulsion system and a steering system in order to deliver the minimum corrective force. This advantageously stabilises the vessel against the stationary structure while reducing energy usage, carbon emissions and/or the use of fossil fuels.

In some embodiments, the contact portion of the vessel is a bow fender that includes a bow pressure sensor. This advantageously facilitates determining whether the vessel is stabilised against the stationary structure, and enables the vessel to be stabilised against the stationary structure efficiently by ensuring the contact portion is in alignment with a stern-to-bow axis through which the propulsion system delivers a thrust force.

Some embodiments further comprise issuing an alert if the contact force measured by the bow pressure sensor falls below a threshold value. This advantageously alerts crew members to a threat that the vessel is at risk of losing stable contact with the stationary structure.

Some embodiments further comprise determining, based on the sensor data, the minimum thrust delivered by a propulsion system required to maintain the vessel in a stable position relative to the stationary structure, and adjusting the configuration of the vessel control system to deliver the minimum thrust. This advantageously stabilises the vessel against the stationary structure while reducing energy usage, carbon emissions and/or the use of fossil fuels.

Some embodiments further comprise determining, from the sensor data, the current vessel operating conditions, including one or more of a sea state, a wind state, and a tide state. This advantageously facilitates automatically controlling the motion and position of the vessel in response to the local weather conditions.

Some embodiments further comprise determining a change in position and/or motion of the waterborne vessel relative to the stationary structure is achieved by comparing sensor data to one or more predetermined thresholds. This advantageously provides an acceptable operating tolerance, or in other words allows the sensitivity of the vessel control system to be tuned, by configuring the vessel control system if the sensor data exceeds predetermined thresholds.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram of a mono-hull vessel having two hydrofoils; Figure 2 is a schematic diagram of a cross-sectional view of a housing for a gearbox and engine arrangement; Figure 3 is a perspective view of a hydrofoil, which includes the housing of Figure 2 and a propeller; Figure 4 is a front view of the hydrofoil and propeller of Figure 3; Figure 5 is a side view of the hydrofoil and propeller of Figure 3; Figure 6 is a schematic diagram of the mono-hull vessel of Figure 1 in a stable attitude against a stationary structure; Figure 7 is a schematic diagram of an autonomous control system; and Figure 8 is a flow diagram showing a example processes performed by the autonomous control system.

The above figures are included to provide illustration and a further understanding of the various aspects and embodiments, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limits of the invention. In the figures, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labelled in every figure.

DETAILED DESCRIPTION

It is to be appreciated that embodiments of the systems and methods discussed herein are not limited in application to the details of construction and the arrangement set forth in the following description or illustrated in the accompanying drawings. The systems and methods are capable of implementation in other embodiments and of being practiced or of being carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use herein of "including," "comprising," "having," "containing," "involving," and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. References to "or may be construed as inclusive so that any terms described using "or" may indicate any of a single, more than one, and all of the described terms.

Aspects and embodiments described herein generally relate to stabilising yachts, sailboats, ships, workboats and other waterborne vessels against a stationary structure. It will be appreciated that in the context of this invention the stationary structure may be an offshore asset such as an off-shore wind turbine, mooring, or dock.

Waterborne vessels Waterborne vessels may be wind powered (e.g. yachts, sailing boats), and/or powered using a propulsion system having an engine and gearbox mechanically engaged to a propeller. The propeller is located on the underside of the hull and provides thrust along the bow-stern axis of the vessel. The propulsion system may further include one or more manoeuvring thrusters that provide thrust at an angle to the bow-stern axis of the vessel to facilitate turning the vessel, e.g. during docking. Such thrusters may also form part of the vessel steering system, which also includes one or more control surfaces, such as the ship rudder or flaps on a hydrofoil, or any other mechanism that enables the vessel to be manoeuvred by exerting a force on the water.

An example of a waterborne vessel is shown in Figure 1, in which the waterborne vessel is in the form of a monohulled vessel 10 and includes a hydrofoil system 18. However, it will be appreciated that a hydrofoil system is not essential for the below-described invention to function.

The example of Figure 1 shows a vessel 10 with two foils 18, each connected to the hull 14 by means of a vertical shaft 30. It is to be appreciated that vessels having hydrofoils will include a minimum of two foils (a foremost foil towards the bow, and an aftmost foil towards the stern of the vessel), one or both of which may include propulsion means. As shown in the example of Figure 1, a propellor 32 is mounted to the aft-most foil only.

In embodiments where the vessel includes one or more foils 18, each foil may be located on the outer surface of the hull below the floating waterline. Each foil 18 may comprise a plurality of adjustment members, which are control surfaces operable to vary the lift characteristics of the foil, and thus the vessel 10 during travel. Each adjustment member comprises a flap 20 and associated actuator 22. Actuators 22 can be either electric or hydraulic and may be integrated within foil 18 (as shown in figure 1) or may be located within the vessel 10 itself depending on the vessel size and associated foil size. Actuators 22 operate to control the position of associated flaps 20 to control the ship in heave i.e. ride height 24 relative to the floating water line 26), pitch, roll and thrust. Where multiple foils 18 are provided, the actuators 22 for each flap 20 of each foil 18 are independently controlled by a single controller 12.

Ride height 24 is shown in figure 1 and is based on the distance between the water surface (floating water line 26) and the foiling water line 28. Foiling water line refers to where the water free surface sits, relative to the foils/hull, while airborne. When the boat is floating, the water line is defined by how much the hull needs to sink to obtain the volume of displacement (under Archimedean hydrostatic force). When foiling, the foiling water line is the optimum between minimum foil immersion ( the vertical part "shaft") to reduce drag without having the elevator 52 ventilating because of the free surface proximity.

The vessel 10 further comprises a control system 12 located within the hull 14. The control system 12 communicates with engine 42 to control the operation of propeller 32. The control system 12 also communicates with actuators to control the position of the control surfaces. In preferred embodiments, the control system 12 controls the operation of the propeller and/or the control surfaces in dependence upon the sensor data. This has the effect of influencing the position and motion of vessel through the water by providing an adjustable counter-force against the pitch, roll, yaw, heave, surge or sway vessel 10.

A battery system 16 may be located adjacent control system 12, and in electrical communication with control system 12. In the embodiment of figure 1, battery system 16 comprises a Power Electronics Control Unit (PECU).

Sensors The vessel 10 is further provided with a plurality of sensors (not shown) in electrical communication with control system 12, each sensor being configured to gather sensor data relating to the position and movement of the vessel in the water, the performance of the vessel, and/or environmental data.

In some embodiments, the sensor data relating to the movement of the vessel may include, for example, data associated with the acceleration of the vessel in any measurement axis (such as the pitch, yaw, roll, heave, surge or sway of the vessel). The sensor data relating to the position of the vessel may include data associated with the position of the boat in relation to the Earth or the seabed, such as GPS coordinates, or the position of the boat in relation to another object, such as LIDAR data. The sensor data may further include pressure sensor data from a contact portion of the vessel, such as a bow fender, that is indicative of the force exerted by the contact portion on another object.

In some embodiments, the sensor data relating to the performance of the vessel may include, for example, data associated with one or more of the speed of the vessel, control system inputs and configurations, engine performance, remaining battery capacity, or the thrust delivered by the propeller.

In some embodiments, the sensor data relating to environmental data may include, for example, data associated with the free surface of a body of water proximate to the vessel, data associated with the wind conditions proximate to the vessel, and/or data associated with the tide conditions of a body of water proximate to the vessel.

The sensors may be located in multiple positions around the vessel, including being embedded in the hull or foils. In some embodiments, at least a portion of the sensor data may be retrieved from a remote data source.

The gathered sensor data is then provided to control system 12, which uses the sensor data to determine whether any adjustments are required to the propulsion system and one or more control surfaces to optimise the vessel's travel through the water.

The sensors may provide the sensor data to the control system on a continuous basis or on demand from the control system or in a predetermined programmed manner. Providing sensor data on a continuous basis enables a real-time feedback loop between the control system 12 and the operation of the vessel 10.

Engine/Gearbox For electrically powered vessels, an engine may be electrically coupled to battery system 16 and control system 12 such that, in use, energy is transferred from the battery system 16 to the engine to thereby drive a propeller drive shaft via a gearbox to rotate a propeller. The engine may act as a generator, deploying energy from the battery system 16 to drive the gearbox. Thus, the propeller is mechanically connected to the engine and gearbox in order to drive the vessel 10 through the water during travel.

As shown in Figure 2, the engine and gearbox may be disposed within a vessel body 34 that forms a housing defining an elongate channel 36 in which engine 42 and gearbox 44 are received. Elongate channel 36 has a first open end 38 and a second end 40 opposing the first end 38, first and second ends 38, 40 being in fluid communication with one another. Propeller 32 is mounted at the second end 40 of channel 36. Engine 42 and aligned gearbox 44 are mounted within elongate channel 36 and mechanically coupled to propeller drive shaft 46. In some embodiments, fluid inlets 48 are provided radially around body 34 such that channel 36 is in fluid communication with the exterior of the vessel body, i.e. exterior water may flow through fluid inlets 48 into channel 44. Thus, when vessel 10 is travelling through the water, water flows through fluid inlets 48 into channel 36 and flows past engine 42 and gearbox 44 in a direction towards the second end 40 of channel 36. Further, water will be drawn in through open first end 38 of channel 36 and also flow past engine 42 and gearbox 44 towards second end 40. The flow of exterior water into channel 36 and around engine 42 and gearbox 44 serves to cool the engine and gearbox during use, preventing overheating and allowing operation of the engine and gearbox at higher speeds than possible in the absence of a cooling system.

In some embodiments, the housing provides a watertight housing for engine 44. One or more of the engine 42 and gearbox 44 may be located within housing and are connected via a drive shaft that transmits the torque and rotation from engine 42 to the gearbox 44.

The outer surfaces of the engine 42 and/or gearbox 44 are located adjacent the interior surface of housing such that heat generated during use is absorbed from engine 42 and gearbox 44 by housing and subsequently dissipated into the surrounding water, thus providing an efficient cooling system that avoids the need for mechanical or forced flow of fluid past the engine 42 and/or gearbox 44 within housing.

In preferred embodiments, the engine 42 may be electrically coupled to battery system 16 and control system 12 via an electrical harness, such that, in use, the electrical harness transfers energy from the battery system 16 to engine 42, which in turn drives propeller drive shaft 46 via gearbox 44 to rotate propeller 32.

In preferred embodiments, gearbox 42 is an epicyclic gearbox and engine 44 is a motor generator unit (MGU). However, it is to be appreciated that this is just one embodiment and the skilled person may use an alternative gearbox and engine to achieve the same arrangement.

Control Surfaces The vessel includes one or more control surfaces operable to adjust the position and movement of the vessel by exerting a force on the surrounding water. An example of a control surface is the vessel rudder, which is actuated to adjust the yaw of the vessel.

Further control surfaces may also be provided where the vessel further comprises a hydrofoil, as shown in the embodiments of Figures 3 to 5.

The embodiment of Figure 3 shows a foil 18 having a vertical shaft 30, a propeller 32 and two pairs of flaps 20 that act as control surfaces. The foil 18 may be connected to the hull 14 of vessel 10 via the vertical shaft 30, which may include a rudder. A propeller 32 is mounted on foil 18 for driving the vessel 10 through the water during travel.

Flaps 20 may be positioned in pairs, with one of the pair positioned on the hydrofoil wing on a first side of propeller 32 with the second of the pair on the opposing side. The flaps 20 may be actuated to adjust the amount of lift provided by the hydrofoil 18, or different sections of the hydrofoil 18, and so adjust the pitch, heave (i.e. the ride height), and/or roll of the vessel. Of course, the hydrofoil 18 itself may function as a control surface by providing a lifting force that is adjustable by controlling the rotation of the propeller, and thus the speed at which the vessel travels, to thereby adjust the heave of the vessel.

As shown in Figure 4, the vertical shaft 30 is aligned with vertical axis A-A and adjustment members 13 are configured to actuate respective flaps 20. Accordingly, each flap 20 is independently operable by an associated adjustment member 13. Preferably, the adjustment members 13 are disposed within hydrodynamic fairings. Actuating the rudder, located on vertical shaft 30, will cause a turning rotation about the axis A-A to thereby adjust the yaw of the vessel.

Embodiment of Figure 5 shows a housing 60 containing engine 42 and gearbox 44, the housing 60 being aligned with horizontal axis B-B. The effect of actuating one or more pairs flaps 20 either side of horizontal axis B-B to deflect in the same direction with respect to the B-B axis will affect the pitch of the vessel 10 by adjusting the amount of lift and drag generated by the foil wing. Actuating the one or more pairs of flaps 20 in opposite directions with respect to the B-B axis will result in the vessel 10 rolling about the B-B axis.

Autonomous Control System Embodiments of the invention are directed towards an autonomous control system for stabilising a vessel against another structure, such as an offshore wind turbine, as further described below and with reference to Figure 6.

Figure 6 shows the vessel 10 previously represented in Figure 1, and further includes a rudder 70, located at the aftmost vertical shaft, and a contact portion, which may be a bow fender 72 located on the bow of the vessel. The bow fender 72 is configured to abut an offshore asset 74, which is fixed in position relative to the seabed. The bow fender 72 provides a high-friction contact between the vessel and the offshore asset 74. Floating water line 76 indicates the position of the water surface for a flat-calm sea state (i.e. a wave height of no more than 0.1 meters).

As previously indicated, existing techniques for transferring personnel and goods between a vessel and an offshore asset include so-called "bump and jump" operations, where the bow of the vessel is driven against an offshore asset at full throttle while the personnel and/or goods are transferred at the bow of the vessel. Such operations are risky, however the increased driving force provided by the propulsion system increases the friction coefficient between the vessel and the offshore asset, which substantially or completely overcomes external forces acting on the boat due to the sea state or weather conditions and thus reduces the relative movement between the vessel 10 and the offshore asset 74.

Indeed, the frictional force may be so strong that the vessel remains in a substantially horizontal position in rough sea states, when wave crests and wave troughs extend significantly above and below the floating water line 76. This is because the frictional force between the bow fender 72 and the offshore asset 74 is large enough to overcome the gravitational force acting on the bow of the boat, even when the bow is not supported by surrounding water during a wave trough, and to overcome a buoyancy force on the bow during a wave crest.

However, as previously indicated, this approach requires very high energy usage. This is because the vessel is driven at full throttle to provide maximum frictional force in order for a skipper to guarantee that the likelihood of the vessel moving during the transfer of personnel and goods is as low as possible, and thus reduce the risk of harming the personnel and goods during transfer.

As further described below, embodiments of the invention are able to stabilise a vessel 10 against a stationary offshore structure 74, i.e. an object that is not subject to sea motion such as an offshore wind turbine, while additionally reducing the energy usage and carbon emissions of the vessel during such operations. This is achieved by providing an autonomous control system that receives sensor data indicative of the vessel's position and motion relative to the offshore structure, calculating a configuration of a vessel control system that will maintain the vessel in a stable attitude against the stationary structure, and configuring the vessel control system accordingly. The autonomous control system is able to continuously monitor the sensor data to determine the real-time environmental conditions, and adjust the thrust delivered by a vessel propulsion system accordingly.

Thus, the autonomous control system is configured to deliver the minimum amount of thrust required in order to maintain the vessel in a stable attitude against the stationary structure. This advantageously results in reducing the energy usage, and associated emissions, during the transfer of crew and goods while still ensuring the safety of the crew and goods.

It will be appreciated that initial contact between the vessel 10 and stationary structure 74 may be achieved using known techniques. For example, the vessel skipper may use a LIDAR sensor to facilitate approaching the stationary structure and making safe initial contact with the stationary structure. Once contact is made, an autonomous control system autonomously maintains stable contact between the vessel and the stationary structure as further described below.

Figure 7 shows an example of how an autonomous control system may interface with other vessel systems. The embodiment of Figure 7 shows an autonomous control system (ACS) 710 in communication with a sensor system 720 and a vessel control system 730.

The ACS 710 may include one or more processors that receive data from the sensor system 720. The ACS 710 analyses the sensor data in order to determine the vessel's position and motion relative to a stationary structure, and thus determine whether action is required in order to maintain the vessel in a stable attitude against the stationary structure.

The ACS 710 may comprise memory and databases in order to establish the corrective action to be taken. The ACS 710 then communicates with the vessel control system 730 in order to change the configuration of the vessel to thereby maintain the vessel in a stable attitude against the stationary structure.

The sensor system 720 may include a plurality of sensors, as described above. The sensors may include vessel position sensors 722 and vessel motion sensors 724. The vessel position sensors 722 may include any sensor suitable for determining the position of the vessel, or environmental factors that may affect the position of the vessel. For example, the vessel position sensors 722 may include one or more of: a LIDAR or Ultrasonic distance sensor, for determining the position of the vessel relative to another object; a GPS module, for determining the position of the vessel relative to the Earth; a bow pressure sensor, for determining the contact force between the vessel bow and a stationary structure; and wind sensors, for measuring the direction and strength of the prevailing wind to thereby determine the effect of the wind on the current position of the vessel. The vessel motion sensors 724 may include any sensor suitable for determining the motion of the vessel, or environmental factors that may affect the motion of the vessel. For example, the vessel motion sensors 724 may include accelerometer sensors, for measuring the acceleration of the vessel, or an inertia measurement unit (IMU) that measures the angular and linear acceleration of the vessel in all axes of measurement.

The vessel control system 730 may include a propulsion system 732 and a steering control system 734. It will be appreciated that the vessel control system 730 may also include control system 12 described above.

The propulsion system 732 may include one or more means for providing thrust. The propulsion system 732 may include one or more of an engine, a gearbox, a propeller, bow and/or stern thrusters for providing lateral propulsion, and associated control circuitry for configuring same. In some embodiments, the propulsion system 732 includes a plurality of propellers. In particular embodiments, the propellers may be counter rotating and may be individually adjusted to control the motion of the vessel. The ACS 710 may provide control signals to the propulsion system 732 in order to adjust the position and/or motion of the vessel by configuring the amount of thrust provided by the propulsion system 732. Additionally, the ACS 710 may receive information from the propulsion system 732, which may relate to the performance or current configuration of the propulsion system 732.

The steering control system 734 may include one or more means for steering or manoeuvring the vessel. The steering control system 734 may include one or more of a rudder, and other control surfaces such as the adjustment members described above; and bow and/or stern thrusters, for providing lateral steering via propulsion. In some embodiments, the steering control system 734 includes a plurality of rudders. Additionally, where vessels have multiple engines and propellers, additional steering may be achieved by setting different thrust levels for the port and starboard sides of the vessel to create a yaw moment. The steering control system 734 may also include associated control circuitry for configuring these components.

The ACS 710 may provide control signals to the steering control system 734 in order to adjust the position and/or motion of the vessel by steering the vessel. Additionally, the ACS 710 may receive information from the steering system 734, which may relate to the performance or current configuration of the steering system 734.

The operation of the ACS 710 is described further below with reference to Figure 8.

Figure 8 shows an example process 800 undertaken by the ACS 710 in order to maintain vessel 10 in a stable attitude against a stationary structure 74, such as an offshore asset.

In a first step 810, gathered data is received by the ACS 710 and processed in order to determine the vessel's position and motion. The gathered data may be sensor data collected from a plurality of sensors located on vessel 10, as described above. In preferred embodiments, the sensors include a bow pressure sensor for measuring the contact load or contact pressure between the vessel 10 and the stationary structure 74 at a contact portion 72 of the vessel 10. The bow pressure sensor may be located in a bow fender, which provides additional friction between a contact portion 72 and the stationary structure 74. The sensors may also include one or more wind sensors for measuring the strength and direction of the prevailing wind. This data may enable the ACS 710 to determine whether additional thrust is required to prevent the prevailing wind from destabilising the vessel 10. The sensors may also include one or more accelerometers, such as an IMU, for measuring the vessel's acceleration, and thus changes to the motion of the vessel. If the ACS 710 determines that the IMU data indicates that the bow of the vessel is starting to drop vertically down the stationary object, due to a wave trough resulting in the bow no longer being supported by a buoyant force, then the propulsion system can be configured to provide additional thrust. The increased thrust results in an increase in friction between the vessel contact portion72 and the stationary structure 74, which overcomes the gravitational force acting on the bow and so stops the movement of the bow down the stationary structure 74.

In alternative embodiments, a portion of the data may be retrieved from a database, such as tide timings for a particular location, or weather forecasts may be obtained from external file sources, such as GRIB (General Regularly-distributed Information in Binary form) files.

While processing the gathered data, the ACS 710 may perform optional step 820 in order to determine whether the vessel contact portion 72 is still in contact with the stationary structure 74. This may be achieved by analysing data from the bow pressure sensor and determining whether the measured contact pressure has fallen below a predetermined threshold. If the measured contact pressure at the bow is below the threshold then this indicates that the bow of the vessel 10 is no longer in contact with the stationary structure 74. There may be a number of reasons why contact between the vessel 10 and stationary structure 74 is lost, for example if the bow is pushed away by the surrounding water or if the bow slips sideways off the stationary structure. In both instances, there is an increased risk to the crew, personnel and cargo. Therefore, if the ACS 710 determines in outcome 822 that the vessel is no longer in contact with the stationary structure, then it may perform step 830 of issuing an alert to the skipper and/or crew of the vessel. The skipper or driver may then make a decision as to whether to re-establish contact by increasing the delivered thrust of the vessel, or to abort the attempted manoeuvre and to start again. If, in outcome 824, the ACS 710 determines that contact is established between the vessel and the stationary structure, then the ACS 710 continues with determining if the vessel is maintaining a stable attitude against the stationary structure in step 840.

In step 840, the ACS 710 processes the determined vessel position and motion established in Step 810 in order to establish whether the vessel 10 is maintaining a stable attitude against the stationary structure 74. In other words, the ACS 710 determines whether the position and motion of the vessel relative to the stationary structure do not each exceed one or more predetermined thresholds. The predetermined thresholds therefore define an acceptable operating tolerance, which may be set very low or to zero to improve operating safety.

If the predetermined thresholds are exceeded then the ACS 710 determines in outcome 842 that the vessel 10 is not in a stable attitude relative to the stationary structure 74, and proceeds to calculate a corrective action in step 850.

In step 850, ACS 710 calculates a corrective action needed to correct the detected change in vessel attitude. The corrective action may be a minimum corrective force required to oppose the identified change in motion or position of the vessel. For example, if the gathered data indicates that the z-acceleration of the vessel bow, or the z-displacement of the bow relative to the stationary structure 74, has exceeded a threshold value, then the ACS 710 calculates the smallest amount of force needed to return the vessel to a stable attitude against the stationary structure. The minimum corrective force may be delivered by increasing the thrust of the propulsion system, or adjusting the configuration of one or more control surfaces of the vessel to thereby dampen the measured change in the position or motion of the vessel. The minimum corrective force may be based on the current vessel operating conditions, such as the sea state, tide state and/or wind conditions, which may be determined from the sensor data. In this context, it will be appreciated that sea state refers to the general condition of the free surface of a large body of water at a given location and time. The tide state refers to the strength and direction of the tide at a given location and time. Similarly, the wind state refers to the strength and direction of the wind at a given location and time.

The corrective action may be any change to the configuration of the vessel control system that is able to correct the motion or position of the vessel relative to the stationary structure. The ACS 710 then identifies a vessel control system configuration that will result in the vessel delivering the corrective action.

In one embodiment, the ACS 710 may determine the base-level vessel control system configuration required to initially make and maintain contact between the vessel and the stationary structure. The ACS 710 may predict how the local environment, such as the sea state and wind conditions, will affect the vessel and then calculate adjustments that need to be made to the base-level configuration based on those predictions such that the vessel maintains a stable attitude against the stationary structure.

In step 860, the ACS 710 implements the new vessel control system configuration in order to dampen or prevent the detected change in position or motion of the vessel relative to the stationary structure and thus return the vessel 10 to a stable attitude against the stationary structure 74.

In preferred embodiments, the vessel control system is configured to adjust the thrust delivered by the vessel propulsion system. As described above, increasing the thrust results in the contact portion 72 of vessel 10 being urged into the stationary structure 74 with increased force such that the frictional force between the vessel 10 and the stationary structure 74 is sufficiently large to overcome other forces on the vessel 10 and thus maintain the vessel 10 in a stable attitude against the stationary structure 74.

In other embodiments, the vessel control system is configured to adjust the steering of the vessel 10 in order to maintain the vessel 10 in a stable attitude against the stationary structure 74. For example, if the vessel undergoes a yaw moment then the ACS 710 may autonomously implement a configuration that adjusts a rudder, one or more hull stern thrusters, a secondary propeller, or any other suitable means of providing an opposing yaw moment that returns the vessel 10 to a stable attitude against the stationary structure 74.

The process is then repeated, returning to step 810 of processing gathered data. Thus, operating in a closed-loop with real-time data ensures that the vessel is maintained in a stable attitude autonomously by the ACS 710.

Returning to step 840, if the ACS 710 determines in outcome 844 that the vessel 10 is in a stable attitude relative to the stationary structure 74, then the ACS 710 may straightforwardly maintain the current configuration of the vessel control system in step 870, and continue to monitor the position and motion of the vessel by returning to step 810.

In preferred embodiments, outcome 844 results in the ACS 710 determining whether the thrust applied by the propulsion system may be reduced in step 880. Once a wave swell or surge recedes there may be a reduced amount of force required to maintain the vessel 10 in a stable attitude against the stationary structure 74. Accordingly, if the ACS 710 determines that the vessel is stable then the ACS 710 may check to see if the applied thrust can be reduced while still maintaining stable contact between the vessel and the stationary structure. The decision to reduce the thrust of the propulsion system may be determined based on data from the bow pressure sensor and environmental data, such as wind data and sea state data.

In some embodiments, the ACS 710 may configure the propulsion system to reduce the thrust in step-wise fashion while continuing to monitor the position and motion of the vessel 10 relative to the stationary structure 74 by returning to step 810 in the process after each step-reduction in thrust before reducing the thrust further.

Accordingly, embodiments of the invention employ a closed-loop control system to autonomously maintain a vessel in a stable position against a fixed object, such as an offshore asset. This enables improvements to the safe transfer of personnel and/or equipment between the vessel and the offshore asset while also minimising the energy requirements and emissions during such a manoeuvre.

The above detailed description of embodiments of the invention are not intended to be exhaustive or to limit the invention to the precise form disclosed. For example, while the description above relates primarily to an electrically powered vessel having a hydrofoil system, it will be appreciated that the invention could also be implemented on conventionally powered vessels that do not include hydrofoil systems. In such embodiments, the vessel control system 730 may comprise a propulsion system 732 that may include one or more of an internal combustion engine, a propeller, and bow and/or stern thrusters. The vessel control system 730 may comprise a steering control system 734 including one or more rudders, and bow and/or stern thrusters.

While processes or blocks are presented in a given order, alternative embodiments may perform routines having steps, or employ systems having blocks, in a different order, and some processes or blocks may be deleted, moved, added, subdivided, combined, and/or modified. Each of these processes or blocks may be implemented in a variety of different ways. Also, while processes or blocks are at times shown as being performed in series, these processes or blocks may instead be performed in parallel, or may be performed at different times.

The teachings of the invention provided herein can be applied to other systems, not necessarily the system described above. The elements and acts of the various embodiments described above can be combined to provide further embodiments.

While some embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms. Furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the disclosure.

Claims

CLAIMS1. A system for stabilising a waterborne vessel against a stationary structure, the system comprising: a sensor system for providing sensor data; a processor configured to receive data from the sensor system, determine from the sensor data a change in the position and/or motion of the waterborne vessel relative to the stationary structure, and calculate a minimum corrective force required to oppose the change; and a vessel control system operable to deliver the minimum corrective force and to thereby oppose the change in the position and/or motion of the waterborne vessel relative to the stationary structure.
2. The system of claim 1, wherein the vessel control system comprises a propulsion system and a steering system.
3. The system of claim 2, wherein the propulsion system includes an engine, a gearbox and a propeller.
4. The system of claim 2, wherein the steering system comprises one or more control surfaces.
5. The system of claim 2, further comprising a battery system in electrical communication with the vessel control system and operable to provide power to the propulsion system and/or steering system.
6. The system of claim 1, wherein the waterborne vessel includes a hydrofoil having a plurality of adjustment members.
7. The system of claim 1, wherein the processor is further configured to determine the current vessel operating conditions, including one or more of a sea state, a wind state, and a tide state, based on the sensor data.
8. The system of claim 1, wherein the sensor system includes one or more vessel position sensors and one or more vessel motion sensors.
9. The system of claim 8, wherein the vessel position sensors include one or more of a LIDAR, Ultrasonic distance sensor, GPS module, bow pressure sensor, or wind sensors.
10. The system of claim 8, wherein the vessel motion sensors include an accelerometer or an inertia measurement unit (IMU).
11. The system of claim 1, wherein the vessel control system is configured to deliver the minimum corrective force by adjusting the thrust delivered by a propulsion system to thereby urge a contact portion of the waterborne vessel against the stationary structure.
12. The system of claim 11, wherein the contact portion of the vessel is a bow fender that includes a bow pressure sensor.
13. The system of claim 1, wherein the engine comprises a Motor Generator Unit (MGU).
14. A method for stabilising a waterborne vessel against a stationary structure, the method comprising: a) receiving sensor data from a sensor system; b) determining, from the sensor data, a change in the position and/or motion of the waterborne vessel relative to the stationary structure; c) calculating a minimum corrective force required to oppose the change; d) adjusting the configuration of a vessel control system to deliver the minimum corrective force and to thereby oppose the change in the position and/or motion of the waterborne vessel relative to the stationary structure; and e) repeating steps a) to d).
15. The method of claim 14, wherein adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting the thrust delivered by a propulsion system to thereby urge a contact portion of the waterborne vessel against the stationary structure.
16. The method of claim 14, wherein adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting one or more control surfaces of a steering system to deliver the minimum corrective force.
17. The method of claim 14, wherein adjusting the configuration of the vessel control system to deliver the minimum corrective force comprises adjusting both a propulsion system and a steering system in order to deliver the minimum corrective force.
18. The method of claim 15, wherein the contact portion of the vessel is a bow fender that includes a bow pressure sensor.
19. The method of claim 18, further comprising issuing an alert if the contact force measured by the bow pressure sensor falls below a threshold value.
20. The method of claim 14, further comprising determining, based on the sensor data, the minimum thrust delivered by a propulsion system required to maintain the vessel in a stable position relative to the stationary structure, and adjusting the configuration of the vessel control system to deliver the minimum thrust.
21. The method of claim 14, further comprising determining, from the sensor data, the current vessel operating conditions, including one or more of a sea state, a wind state, and a tide state.
22. The method of claim 14, wherein determining a change in position and/or motion of the waterborne vessel relative to the stationary structure is achieved by comparing sensor data to one or more predetermined thresholds.