Patent Application
20240367768
The present invention relates to submersible vehicles, and more specifically to a power system to manoeuvre submersible vehicles.
Submersible/underwater vehicles are increasingly employed in underwater work, where it is dangerous and expensive to send personnel. Underwater vehicles are used widely, for example to assist with oil and gas production, survey, military, scientific, aquaculture, and marine conservation operations. In aquaculture settings, the operating depths of such vehicles is from 0 m to around 45 m. In some other applications, underwater vehicles dive significantly deeper than 45 m.
Underwater vehicles are often remotely operated vehicles (ROVs) that receive instructions from a remote location (generally not underwater). Some underwater vehicles are autonomous, having an onboard control system.
ROVs have found use in fish farming. Previously fish enclosures would be typically inspected twice-weekly by SCUBA divers, and any dead fish would be removed to prevent spread of disease or outbreaks of sea-lice infestation. More recently, ROVs have been used to carry out inspection and removal of dead fish. In prior art document WO2019/135070, the contents of which are fully incorporated by reference herein, a device is provided for use with an underwater ROV, wherein the device comprises a mouth for sucking dead fish into a cage using water jets to provide the suction.
Typically, an underwater vehicle is launched from the side of a boat or offshore installation, or the side of a river or lake, and is controlled as an ROV by an operator at the surface. The ROV may be connected to the surface by a tether, i.e., a cord or flexible attachment. The tether may comprise an umbilical connection typically providing electrical communication between the ROV and the surface. For example, the umbilical may include one or more of: electrical power cabling; communication cabling for control of the ROV; communication cabling for transmission of video or sensor data.
Most underwater ROVs comprise a buoyancy pack, often made of syntactic foam, on top of a (typically aluminium or High-Density Polyurethane “HDPE”) chassis. A “Skid” i.e., an additional chassis may take the form of an additional framework structure. Specialised tooling or equipment can be attached to the chassis for use underwater. The chassis or skid may be fitted with sensors, cameras, lights, torque tools, probes, or any useful piece of equipment for work underwater. Electrical equipment on the chassis is typically powered and controlled by power supply and control signals delivered via the tether. Hydraulic power may also be provided by hydraulic lines in the umbilical or alternatively through a hydraulic power unit fitted to the ROV as a means to convert electrical power to hydraulic power, or as separate hydraulic lines to the equipment. Where multiple different pieces of equipment are operating simultaneously on the ROV, such as cameras and gripping tools, then each piece of equipment may be connected to a junction box or control manifold on the ROV which in turn is connected to an umbilical leading to the surface.
In terms of movement and control of underwater ROVs, thrusters are usually provided in the form of propellers to provide positional and attitude control during deployment. The thrusters are usually powered by an electrical or hydraulic connection from the surface. However, some ROVs carry a power source such as a battery or Hydraulic Power Unit to generate power to drive thrusters and rotate the propellers in the direction required for motion.
Despite the development of a wide range of options for underwater vehicles, improvements in efficiency and utility are still desired.
It is an object of the present application to provide improvements to underwater vehicles and their propulsion systems.
The present invention provides a submersible vehicle comprising: a plurality of outlet nozzles arranged to receive pressurised fluid from a remote supply and expel the pressurised fluid to create propulsion to manoeuvre the vehicle; and a plurality of valves in fluid communication with the outlet nozzles and operable to provide variable pressure and/or flow to each outlet nozzle; wherein the outlet nozzles are arranged about the vehicle to provide six-degrees of freedom movement and control of the submersible vehicle.
This arrangement is convenient because motors or other propulsion mechanisms do not need to be located under water. This simplifies the structure of the submersible vehicle which allows it to be lighter, more reliable, and easier to manufacture and maintain. Advantageously the pressurised flow of fluid is water, typically from the body of water (e.g., fresh or salt) the vehicle is disposed in, as discussed further hereafter. However, operating the vehicle in a liquid that is not fresh or salt water is also contemplated. For example, in a tank containing an aqueous solution or even a non-aqueous liquid.
Advantageously, the outlet nozzles are configured to provide propulsion of the vehicle underwater and/or on the surface. A plurality of outlet nozzles allows precision directional control and/or movement of the vehicle.
The vehicle may be a remotely operated vehicle. The remotely operated vehicle will be connectable to a remote-control unit, typically via an umbilical connection. The vehicle may be an autonomous vehicle. Where the vehicle is autonomous the control unit (e.g., a computer receiving sensor data and/or sending control signals) may be onboard the vehicle. Alternatively, the control unit may be remote from the vehicle and may be connectable to the vehicle via an umbilical connection (i.e., the vehicle may be an autonomous remotely operated vehicle). Remotely operated vehicles are useful in many industrial environments where access is difficult, dangerous or expensive. Controlling remotely and above the water (e.g., from shore, a platform or onboard a floating vessel) allows the use of non-waterproof equipment, connecting to the submersible vehicle via umbilical arrangements.
The submersible vehicle may be configured such that the propulsion provided by the flow from the outlet nozzle or nozzles provides directional control (steering and orientation) and/or movement of the vehicle from one location to another (underwater and/or on the surface). Conveniently both directional control and movement are provided by the flow from the outlet nozzle or nozzles. However mixed arrangements are envisaged. For example, movement through the water provided by an electrically driven propeller and fine directional control by the use of flow through outlet nozzles.
Each outlet nozzle may be connectable to a distinct/separate supply hose. This provides a dedicated supply of pressurised fluid for each nozzle which can provide a degree of redundancy to the system. Failure of one or more hoses may not cause complete loss of control and/or movement of the vehicle. Arrangements where a plurality of hoses are provided, with each connecting to one or more outlet nozzles are also contemplated.
The submersible vehicle may further comprise a manifold operable to receive fluid from a single supply hose, wherein the manifold provides a plurality of outlets, wherein each manifold outlet connects to a corresponding outlet nozzle and supplies pressurised fluid thereto. This provides a simple point of connection for the supply hose on the vehicle.
The outlet nozzles may be arranged such that expelled fluid from one or more outlet nozzles, or a combination of outlet nozzles produces at least one of: heave; surge; sway; roll; pitch and yaw motions of the vehicle.
Orientation of one or more of the outlet nozzles may be fixed in position on the vehicle. This can provide a propulsion arrangement without moving parts on the vehicle. Good control of a vehicle can be achieved by using a plurality of fixed outlet nozzles providing propulsion in different directions, as discussed further hereafter. Fixed outlet nozzles can be simpler in manufacture and may be more reliable as there are no moving parts on the submersible vehicle.
Alternatively, or additionally, to one or more outlet nozzles being of fixed position, the orientation of one or more of the outlet nozzles may be adjustable. This allows the user to re-orientate the nozzle between at least two positions, allowing one outlet nozzle to provide at least two different directions of fluid flow from the outlet nozzle. Thus, one moveable outlet nozzle can be used to provide propulsion in different directions. Where moveable nozzles are employed, fewer nozzles may be required to provide all the desired motions of the submersible vehicle. Nozzle adjustment may be provided, for example by means of a motor, such as an electric pneumatic or hydraulic motor. Conveniently nozzle adjustment may be powered by hydraulic power provided by the same pressurised flow of fluid supplied to outlet nozzles.
The plurality of valves may be configured to open or close the fluid flow to one or more outlet nozzles, or to adjust the flow to one or more outlet nozzles. The valve arrangement can control the propulsion generated by the fluid flow from each outlet nozzle to allow the user or control system to provide propulsion. Propulsion from a nozzle outlet controlled by a valve can be intermittent (i.e., open or closed) and/or with variable amount of force (partially open). As an alternative to a valve arrangement mounted on the vehicle to control flow from an outlet nozzle, the supply of pressurised fluid supplied by a delivery hose from the remote supply may be varied.
The submersible vehicle may include external corners and each corner may include a downward heave outlet nozzle and an upward heave outlet nozzle. Each corner may also include a translational outlet nozzle, wherein opening forward located translational outlet nozzles only or rearward located translational outlet nozzles only causes translational movement of the vehicle.
The submersible vehicle may further comprise a separate outlet nozzle, a ‘dump nozzle’, configured to release some or all of the pressurised flow of fluid being delivered from the remote supply. The dump nozzle may be configured to release fluid flow without creating a substantial amount of propulsion, or even any effective propulsion. The dump nozzle may for example be configured to release fluid from a substantially larger cross section area of nozzle than a nozzle used for propulsion.
The fluid expelled through the dump nozzle may be controlled by a dump valve. The control may be intermittent (e.g., on or off) and/or with a variable amount of force.
A dump nozzle and optional dump valve arrangement may be employed to allow a pump supplying the flow of pressurised fluid to run continuously whilst avoiding damage due to over pressurisation when one or more of the outlet nozzles are closed or partially closed.
As an alternative or an addition to the use of dump nozzle arrangements described above, the outlet nozzle or nozzles and any associated valve arrangements may be used to avoid over pressurisation, by allowing fluid to escape even when the vehicle is stationary.
For example, fluid may be allowed to release continuously from two or more nozzle outlets that act in different (e.g., opposite) directions so that there is no net force that steers or moves the vehicle from its current attitude and location in the liquid.
For example, if the buoyancy of the vehicle is less than that required to prevent sinking, then in use, one or more nozzle outlets that are directed to provide lift may be kept at least partially open. This can counteract sinking, whilst providing a constant outlet for fluid flow. Alternatively, if the vehicle is buoyant, tending to float, then outlet nozzles directed to cause diving may be kept at least partially open during submerged work.
A submersible vehicle system may include the submersible vehicle, a pump; a control unit connectable to the vehicle by an umbilical; and a hose connectable to the vehicle, wherein the hose is configured to supply pressurised water via the pump to the vehicle.
The pump may be non-submersible i.e., not water or other liquid proof. The non-submersible pump can be of any type e.g., an electrical motor or engine (e.g., petrol or diesel) driven pump. A non-submersible pump may be easier to maintain. Alternatively, a submersible pump may be employed.
A water or other liquid inlet to the pump may be configured to be located in the same body of water or other liquid as the vehicle. For example, an inlet hose extending into the water and connecting to the inlet of a non-submersible pump mounted above the water. This removes the need for an additional source of water or other fluid to be provided to the pump and allows continuous running of the pump without requiring replenishment of a stored supply of fluid.
The control unit may comprise an electrical power source and may be connected to the vehicle by an electrical umbilical for power and/or signal transmissions. The provision of an electrical power source can allow supply to onboard electrical or electronic equipment, such as valves, cameras, lights or auxiliary equipment.
The pump supplies sufficient pressure of fluid to the vehicle for creating the required propulsion for manoeuvring the vehicle at the depths the vehicle will operate.
The prior art and embodiments of the invention will now be described with reference to the following drawings, in which:
The user typically launches the ROV 110 from a fixed or floating platform, such as a ship or oil rig, or alternatively the ROV 110 may be launched from the shore of a body of water. The ROV 110 is placed in the water and is typically lowered on a winch until the ROV 110 reaches a depth at which it is neutrally buoyant.
The user operates the hand controller 140 to manoeuvre the ROV 110 as required. The ROV 110 moves in the water by the thrusters 150 creating propulsion. The thrusters 150 may be configured to be of adjustable output, whereby increased rotational speed increases propulsion, or alternatively they may have a simple on/off output whereby the user can turn the thrusters 150 on and off individually and intermittently when movement in a particular direction is required.
Most commercial ROVs have six degrees of freedom in that they can move in three dimensions on the x, y and z axes, referred to as surge, sway and heave respectively, as well as rotate around those axes. The rotations are referred to as roll (around the x-axis), pitch (around the y-axis) and yaw (around the z-axis). The position of the thrusters 150 allows control of the ROV 110 in this regard.
Where the terms “water”, “underwater”, “submerged”, “submersible”, “liquid” and such like words are used they are to be construed as not limited to water per se, but instead any liquid within which a vehicle may be manoeuvred in. For example, submersible vehicles in accordance with the present invention may be deployed in industrial chemical tank. Furthermore, it will be understood that the same principles herein described can be applied to autonomous or semi-autonomous submersible vehicles.
The pressurised water system 240 is remote from the ROV 210, in that it is not mounted on the ROV 210 or submerged within the body of water in which the ROV 210 operates. In some embodiments the pressurised water system 240 is located on a boat, a riverbank, an offshore platform, or another surface structure. It is highly advantageous to locate the pressurised water system 240 on dry land (i.e., not submerged). In use, water, from the body of water in which the ROV 210 is operating, or another body or vessel of water, is sucked into the pressurised water system 240 at a water suction inlet 240a and provided to a water pump 240b. The water is then pressurised and provided to the ROV 210 via a suitable water hose 240c. The water is delivered to nozzles positioned around the ROV 210 and is pumped out through the nozzles to create propulsion. A single hose 240c may be used to deliver fluid to the nozzles, or individual hoses (not shown) may be used to deliver fluid to the nozzles. Where a single hose is used, a manifold may split the hose into a plurality of individual lines for providing fluid to each nozzle. The water pump 240b is configured to provide water to the ROV 210 at a pressure higher than the hydrostatic pressure at the ROV 210 when submerged in use. In this regard, the water pump 240b is able to provide the ROV 210 with a flow of water which can be used to propel or steer the ROV 210 underwater.
Each corner of the ROV 210 is provided with a downward heave nozzle 301 and an upward heave nozzle 302, each of which is positioned substantially vertically, i.e. longitudinally in the z-axis, such that a pressurised jet from the downward heave nozzle 301 creates downward propulsion and a high-pressure water jet from the upward heave nozzle 302 creates upward propulsion.
As shown in the plan view in
The downward heave nozzles 301 and upward heave nozzles 302 can also be used to effect pitching of the ROV 210. To effect pitching upwards (i.e. lifting the bow of the ROV) only the rear downward heave nozzles 301 and/or the front upward heave nozzles 302 may be opened, or alternatively to effect pitching downwards (i.e. lifting the stern of the ROV) only the front downward heave nozzles 301 and/or rear upward heave nozzles 302 are opened.
Similarly, the downward heave nozzles 301 and upward heave nozzles 302 can also be used to effect rolling of the ROV 210. To effect rolling to the starboard side, only the starboard side downward heave nozzles 301 and/or the port side upward heave nozzles 302 may be opened, or alternatively to effect rolling to the port side, only the port side downward heave nozzles 301 and/or starboard side upward heave nozzles 302 may be opened.
Referring once again to
Surge of the ROV 201 is caused by opening only the front translational nozzles 303 as shown in the plan view in
Sway of the ROV 201 is caused by opening only the translational nozzles 303 on one side of the ROV 201 as shown in the plan views in
When the translational nozzles 303 are positioned at an angle to the x-axis as in the current example, both of the translational nozzles 303 on one side must be opened together to move the ROV 201 towards port or starboard without rotation of the ROV 201.
Yaw of the ROV 201 is caused by opening only one translational nozzle 303 or, as in the example shown, supplementing the propulsion caused by the opening of one translation nozzle 303 with the diagonally opposing translational nozzles 303, as shown in the plan views in
Whilst in the described embodiment the nozzles are configured to steer and move the ROV 201, in some other embodiments the nozzles may be configured to only steer the ROV 201 whilst movement is provided by another method of propulsion such as traditional thrusters. In some other embodiments, the nozzles may be configured to only move the ROV 201 while steering is provided by another method of propulsion such as traditional thrusters. In some embodiments, steering and movement of the ROV 201 are provided by the nozzles and steering and/or movement are supplemented by other forms of propulsion.
It will be understood by the skilled person that although opened/closed nozzles are referred to above, the nozzles may in some embodiments never completely close and instead remain partially open to allow some water to flow therethrough without creating significant propulsion. This may be advantageous to avoid sticking of nozzles in some designs, particularly in ROVs used in increased water depths. Similarly, the nozzles may be arranged to have a variable flow rate such that various degrees of propulsion can be provided, or they may be simply arranged to be open or closed with a generally constant flow rate when the nozzle is opened. A valving arrangement may be provided to provide variable pressure and/or flow at each nozzle.
The internal configuration of the ROV 201 is now described with reference to
In the presently described embodiment, operation of the nozzles 301, 302, 303 is controlled by a series of valves. The valves are arranged in a starboard valve assembly 401 (shown in
Alternatively, to the above-described electrical control of the valves, the valves may instead be controlled by hydraulics, with the provision one or more hydraulic lines from the surface.
Although not shown in the drawings, the ROV 201 may be connected to submersible devices such as the device for collecting fish described in WO2019/135070. Advantageously, when connected to such devices, the hose may be utilised to provide pressurised water to the device. In this regard, the device may be connected to the auxiliary valve assembly 403 as previously described. Alternatively, the device may be attached to a skid or rack of the ROV 201, and the high-pressure hose may provide pressurised water directly to both the device and the valve assemblies 401, 402.
The dump valve 404 may be connected to a large diameter outlet port (not shown) or a large diameter nozzle (not shown), The outlet port or large diameter nozzle may have a diameter of 1.5 times the diameter of the heave nozzles 301, 302 or translational nozzles 303. In some embodiments, the large diameter outlet port or large diameter nozzle may have a diameter 2, 3, 4, 5 or 6 times larger than the diameters of any of the other nozzles 301, 302, 303. Alternatively, or in addition to the provision of a larger diameter, the dump valve 404 may be connected to a nozzle or outlet port with a diffusion means such as a baffle arrangement to slow and control the flow of water to reduce the propulsion caused by the exhaust of the water.
In some embodiments there may be several dump valves 404 to allow the pressure within the water hose 240c to be released in a controlled manner without causing significant propulsion. In other embodiments there may be one dump valve 404 arranged to provide flow to a plurality of large diameter nozzles or outlets, or nozzles or outlets comprising diffusion means.
In some embodiments there may be a plurality of dump valves 404 arranged such that any propulsion caused by water flow therefrom is balanced by a dump valve 404 providing propulsion in the opposite direction. In such arrangements the dump valves 404 need not comprise large diameter nozzles or diffusion means and may be of substantially similar diameter to nozzles 301, 302, 303.
It will be understood that the control unit 230 will either be configured to allow the user to select operation of the dump valve 404, or preferably the system will automatically open the dump valve 404 when the nozzles 301, 302, 303 are closed. In some embodiments the dump valve 404 may be configured to partially close, i.e., have a variable flow capability. This is advantageous as it allows the dumping of excess pressure when some but not all of the nozzles 301, 302, 303 are closed. In this way, the dump valve 404 assists in ensuring that there is not a significant backpressure generated in the water hose 240c which could stall or damage the pump or cause rupture of the water hose 240c or other equipment such as the valves in the valve assemblies 401, 402.
In some embodiments, the dump valve(s) 404 may be arranged to be always at least partially open in use. In this regard, the dump valve(s) 404 may be positioned substantially vertically such that water released through the dump valve(s) 404 will create propulsion causing either upward heave or downward heave. This can be used to assist in maintaining neutral buoyancy of the ROV 201, and in some embodiments, there may be several dump valves 404 and the user or control system can select which dump valves 404 to bleed excess pressure through to assist with buoyancy control, tidal compensation or any other specific considerations required in the environment and conditions in which the ROV 201 will operate.
Alternatively, to the arrangement described in above and shown in
In any of the previously described embodiments, some or all of the nozzles 301, 302, 303 may have a variable flow rate. Advantageously, some of the nozzles 301, 302, 303 may have a variable flow rate which allows the nozzles to effectively become dump valves 404, whereby the nozzle 301, 302, 303 is able to change shape or configuration enough to reduce the propulsion generated through the nozzle 301, 302, 303 to a sufficiently low level that a dump valve 404 is not required in the system.
Although reference is made to the pumping of water through the pump 240b, water hose 240c and nozzles 301, 302, 303, it will be appreciated that any fluid may be used.
Whilst specific embodiments of the present invention have been described above, it will be appreciated departures form the described embodiments may still fall within the scope of the present invention as defined in the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2104841.8 | Apr 2021 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2022/050851 | 4/5/2022 | WO |
