Process and method for binary counteracting buoyancy for large underwater lifting applications

Abstract

A deep sea apparatus for collecting deep sea tuberculosis is provided. The deep sea equipment includes a counter configured to provide static buoyancy to the deep sea equipment. The deep sea equipment also includes a thruster coupled to the counter, the thruster configured to provide dynamic buoyancy to the deep sea equipment. The deep sea equipment further comprises a variable load and a gas supply system, the gas supply system comprises a gas cylinder connected to a gas valve of the counterpart, and the gas supply system is configured to respond to the change of the vertical position of the counterpart caused by the mass change of the variable load, and a preset amount of gas is injected into the counterpart from the gas cylinder.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 394,199, entitled “Process and Method for Dual Counteracting Buoyancy for Large Subsea Lift Applications,” filed on August 1, 2022, and the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates generally to deep sea mining systems and, more particularly, to dynamic buoyancy systems for deep sea mining systems. The dynamic buoyancy systems employ variable buoyancy conditions that allow the deep sea mining systems to descend, collect ore nodules from the sea floor, and ascend without contacting the sea floor to limit impact on the environment. Background Art

[0004] As the world transitions to green energy solutions, there is a growing demand for storing energy in reusable batteries made of key metals such as nickel, copper and cobalt. Currently, there are few sources of these metals remaining on land, and these land-based resources may be located in challenging locations and / or within sensitive ecosystems. Deep-sea mining is an untapped source of key metals in the form of ore nodules (e.g., polymetallic iron-manganese nodules) and has been a focus of the mining industry in recent years.

[0005] Technical challenges associated with deep-sea mining include the ocean depths (e.g., 5 km to 6 km) and extreme pressures (e.g., between 500 bar and 600 bar) at which mining of ore nodules occurs, and the technology required to transport the mined ore up to the ocean surface. Two systems have been extensively studied and determined to be feasible on a small scale: (i) seabed dredging collection systems, which pump ore to the surface as a slurry through vertical risers, and (ii) mechanical lifting systems, which use synthetic ropes. However, both systems have reliability and scalability issues, and may cause irreparable damage to sensitive environments due to the disturbance of the seabed caused by the mining process.

[0006] Therefore, more sustainable ways of collecting minerals from the seafloor are needed while keeping the seabed ecosystem intact. Summary of the invention

[0007] Disclosed herein are implementations of dynamic buoyancy systems for deep sea mining systems and methods of using the same. According to some embodiments, the disclosed dynamic buoyancy system enables the deep sea mining system to hover at a predetermined distance from the seabed throughout the mining process, which minimizes the environmental impact of the mining process. In addition, the deep sea mining system using the dynamic buoyancy system disclosed herein can be expanded and deployed as a fleet of vehicles with redundancy. According to some embodiments, the dynamic buoyancy system enables the deep sea mining system to descend to the seabed, travel along the seabed without contact while collecting ore nodules, and then rise to the surface to deliver its payload. The dynamic buoyancy system employs variable buoyancy technology and uses a counter / thrust device designed to operate in a reduced power mode at a planned ocean depth as the deep sea mining system descends, collects ore, and ascends without contacting the seabed and with minimal environmental impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings, which are incorporated as a part of this specification, illustrate presently preferred embodiments, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain and teach the principles described herein.

[0009] Figure 1 An exemplary deep sea mining system is shown in accordance with some embodiments.

[0010] Figure 2 An exemplary counteracting / thrust device for deep sea operations is shown, in accordance with some embodiments.

[0011] Figure 3 is a top view of an exemplary buoyancy system equipped with four counteracting / thrusting devices for deep sea operations, according to some embodiments. DETAILED DESCRIPTION

[0012] In deep sea mining, as weight is added to or removed from an underwater vehicle, the buoyancy acting on the vehicle changes. Therefore, it is necessary to compensate for the change in buoyancy caused by weight loss or weight gain. The use of air bladders that expand and displace water is one way to adjust buoyancy underwater. Because the water becomes denser as pressure increases (e.g., at depths where polymetallic nodules can be found and mined), more air is needed to achieve the same amount of lift.

[0013] Figure 1An exemplary deep-sea mining system 100 is shown deployed from a mining vessel 110 for collecting ore nodules 120 disposed on the seabed according to some embodiments. The deep-sea mining system 100 is lowered near the seabed and hovers above the seabed during ore collection. In some embodiments, the deep-sea mining system 100 includes an underwater autonomous vehicle (UAV) 130, an ore collection system 140, a payload hopper 150, and a dynamic buoyancy system 160, wherein the ore collection system 140 collects ore nodules 120 from the seabed, the payload hopper 150 is used to temporarily store the collected ore, and the dynamic buoyancy system 160 enables the deep-sea mining system 100 to move primarily in a vertical direction z (e.g., descend from the ocean surface to the seabed, and ascend from the seabed to the ocean surface).

[0014] According to some embodiments, UAV 130 is equipped with thrusters (in Figure 1 The thrusters enable the deep sea mining system 100 to move primarily in a lateral direction (e.g., parallel to the sea floor - along the xy plane) and secondarily in a vertical direction (e.g., along the z direction). By way of example and not limitation, the ore collection system 140 may be equipped with a robotic arm 140a that may extend toward the sea floor and reach the ore nodules. In some embodiments, when the deep sea mining system 100 is hovering above the sea floor, the robotic arm 140a may be moved by using a robot arm that is not in the sea floor. Figure 1 The ore nodules are collected by picking up the ore nodules using a suitable end effector as shown in FIG. After being picked up, the ore nodules can be placed into a payload hopper 150 .

[0015] According to some embodiments, the deep sea mining system 100 uses an underwater survey and inspection system to locate ore nodules 120 on the sea floor and determine whether marine life is rooted on the nodules. By way of example and not limitation, the deep sea mining system 100 can be configured to avoid collecting ore nodules on which marine life is rooted. After the payload hopper 150 is filled, the dynamic buoyancy system 160 enables the deep sea mining system 100 to rise to the surface of the ocean and deliver its payload. In some embodiments, the dynamic buoyancy system 160 is configured to enable the deep sea mining system 100 to maintain neutral buoyancy at any depth, and particularly at depths near the operating depth, while limiting the use of electric thrusters to save energy.

[0016] According to some embodiments, the components of the deep sea mining system 100 (e.g., the dynamic buoyancy system 160, the payload hopper 150, the ore collection system 140, and the UAV 130) operate in coordination. In some embodiments, these components may be integrated into a single housing, or may operate as detachable modules that are physically and communicatively connected to each other. According to some embodiments, during the collection / mining process, the dynamic buoyancy system 160, the payload hopper 150, the ore collection system 140, and the UAV 130 are physically attached to each other, and during the mining and ascent process, at least the payload hopper 150 and the dynamic buoyancy system 160 may be physically attached to each other. In some embodiments, the dynamic buoyancy system 160 may provide the required buoyancy to compensate for the collected ore during the mining process and during the ascent of at least the payload hopper 150 or the entire deep sea mining system 100. In some embodiments, if the dynamic buoyancy system 160 and the payload hopper 150 rise to the ocean surface on their own, the UAV 130 can use its thrusters to provide the necessary buoyancy for the deep-sea mining system 100 until the dynamic buoyancy system 160 and the payload hopper 150 are lowered from the ocean surface again to be reattached to the deep-sea mining system 100.

[0017] In some embodiments, the deep sea mining system 100 may include additional components, modules, and systems necessary for its intended operation. Figure 1 These additional components, modules, and systems are not shown in the drawings. By way of example and not limitation, these additional components, modules, and systems may include cables, one or more onboard computers, electronics, additional thrusters, motors, batteries, communications equipment, cameras, radars, controllers, global positioning systems, etc. These additional components, modules, and systems are within the scope of the present disclosure. In some embodiments, the deep-sea mining system 100 may operate in an autonomous mode, a semi-autonomous mode, a manual mode, or a combination thereof, based on instructions from the mining vessel 110. In yet another embodiment, the deep-sea mining system 100 may be communicatively coupled to and physically connected to the mining vessel 110 via a cable or other suitable means.

[0018] Autonomous submersible vehicles or untethered submersible vehicles, such as the deep sea mining system 100, operate with a limited amount of power. In most cases, submersible vehicles use electrical energy to generate propulsion / thrust. When the lift or buoyancy adjustment of a submersible vehicle is based on thrust, it may result in a significant increase in power demand and propulsion demand, which translates into a continuous power drain on the energy resources of the vehicle.

[0019] On the other hand, increasing the power storage of a submersible vehicle increases the mass and volume of the vehicle, which is undesirable. In aircraft design, lift, thrust for lift / speed, and weight are carefully considered parameters. For example, for a new aircraft design, when the mass of the aircraft increases, the lift acting on the wings of the new aircraft must increase to offset the increased mass. Lift is increased by increasing: (i) the wing surface area, which adds more weight; and (ii) the thrust provided, which requires a larger and heavier engine. A larger wingspan also means a higher fuel capacity, which also increases weight. Therefore, there is a series of interrelated causes and effects in which two or more elements exacerbate and worsen each other. The system described in this article interrupts this mutual cause and effect cycle.

[0020] As the mass to be lifted increases and the time of non-static operation increases, the weight and power requirements of the vehicle also increase. For example, the energy (e.g., work W) transferred to an object via the application of a force F along a displacement S is given by the following equation (1):

[0021] W (joule) = F (newton) · S (meter) (1).

[0022] The work W done during a time period of duration t is given by the following formula (2).

[0023] W (joule) = P (watt)· t (second) (2), where P is power or the amount of energy transferred per unit time.

[0024] There are temporal complexities when buoyancy sources interact with large changes in mass. Therefore, the associated rates make it difficult for control algorithms to manage these interactions. In addition, submersible vehicles are primarily focused on observation tasks or interactive tasks. Therefore, autonomous submersible vehicles tasked with very large-scale mass collection are rare. Autonomy and relative mass collection as a ratio to the original vehicle mass are even rarer. Therefore, there are no known or established energy reduction methods in existing systems. Advantageously, the deep sea mining system 100 disclosed herein is equipped with a countermeasure / thrust device that minimizes the energy consumption of the deep sea mining system 100 during operation.

[0025] According to some embodiments, the thrusters of a submersible vehicle generate energy-consuming dynamic buoyancy (DB) relative to the scalar volume of the thrusters. On the other hand, non-energy-consuming energy such as lift packs generate static buoyancy (SB). Therefore, a submersible vehicle equipped with a lift pack (also referred to herein as a "countermeasure") and a thruster, at any given time, will have a total combined buoyancy (RB) provided by the following formula 3, the lift pack and thruster are collectively referred to herein as countermeasures / thrust devices:

[0026] RB = SB + DB (3).

[0027] According to some embodiments, the amount of dynamic buoyancy DB generated is proportional to the amount of energy E consumed (e.g., DB∝│E│). And because both negative DB and positive DB consume energy E or power P, power P is defined as the amount of energy consumed per unit time (e.g., P=dE / dt), it is desirable to minimize the demand for dynamic buoyancy DB so that power P (e.g., energy consumed per unit time) is minimized (e.g., DB→0, P→0). However, in order to maintain the total combined buoyancy RB constant (or within an acceptable level) according to Formula 3, the static buoyancy SB must compensate for the loss of dynamic buoyancy DB. In other words, minimizing DB requires maximizing SB to maintain a constant RB.

[0028] Challenges of countermeasures / thrust devices

[0029] When a lift bag filled with a gas or gas mixture (e.g., air) is immersed in water, a change in the water pressure results in an opposite change in the volume of the gas within the lift bag, as described by Boyle's law, which states that the pressure of a system is inversely proportional to the volume of the system (e.g., P ∝ V -1 ). For example, when a balloon filled with air descends into the water column, the water pressure (e.g., hydrostatic pressure) surrounding the balloon increases with depth. The increased water pressure compresses the balloon, which begins to decrease in volume (V↓) as the hydrostatic pressure increases. At the same time, the internal pressure of the balloon increases (P↑) according to Boyle's law. Conversely, as the balloon ascends, the hydrostatic pressure decreases, which causes the gas inside the balloon to expand. This also causes the volume of the balloon to increase (V↑) according to Boyle's law.

[0030] Since the buoyancy force acting on the balloon is proportional to the volume of the balloon (the volume of the balloon defines the amount of water displaced), the buoyancy force increases as the balloon expands during ascent and decreases as the balloon contracts during descent. Thus, during ascent or descent of the balloon, the buoyancy force acting on the balloon changes at a variable rate with depth change until the fluid drag increases to a point where equilibrium conditions are reached. This means that a lift bag filled with a fixed amount of gas experiences a change in its buoyancy force when its vertical position changes (e.g., its depth in a water column changes). And because, as described above, the buoyancy force changes at a variable rate, the buoyancy force may overshoot (e.g., become very positive or very negative) in either direction, depending on whether the lift bag is ascending or descending. This effect is called SB overshoot. Due to this effect, the SB generated by the lift bag in the counter / propulsion device can become variable if not controlled. Therefore, for deep-sea operations, the lift bag or a similar SB source would need to be modified. For example, a system is needed to inject gas into the lift bag during descent and release gas from the lift bag during ascent to account for the change in hydrostatic pressure.

[0031] In addition, it is necessary to control second-order effects or time-delay effects, such as the rate of change of SB when gas is injected into or released from the lift bag of the counter / propulsion device. The SB generated by the lift bag stabilizes slowly as the gas settles (e.g., as the gas reaches an equilibrium state within the volume of the lift bag), which is substantially lower than the rate of change of DB generated by the thruster (e.g., dSB / dt < dDB / dt). For example, when compressed air is introduced into a lift bag immersed in water, it can take up to 30 seconds for the gas to settle and the buoyancy vector to stabilize. In contrast, the DB provided by the thruster is almost instantaneous. Therefore, when gas is injected into the lift bag of the counter / propulsion device, the DB from the thruster can be used to counteract the second-order effect - for example, until the gas settles in the lift bag. This also applies when gas is released from the lift bag.

[0032] The combination of second-order effects and SB overshoot makes the use of counter / propulsion devices challenging for deep-sea operations. However, in scenarios where the payload or weight of a deep-sea mining vehicle changes during the mining process, using SB instead of DB can achieve energy savings. For example, when the buoyancy force generated by the SB device counteracts the weight of the payload, and the DB is wisely used to prevent overshoot and second-order effects.

[0033] Because maximizing the use of SB increases the likelihood of overshoot events or second order effects, a counterbalancing amount of DB may be necessary in the counteracting / thrusting device, as described above. This counterbalancing amount of DB may be optimized according to existing conditions to minimize energy consumption. For example, an amount of power may be budgeted for a mobile submersible vehicle as the vehicle's load or weight changes.

[0034] Description and operation of antagonist / thrust devices

[0035] According to some embodiments, the source of lift or positive buoyancy is a gas-driven lift bag, which may or may not have the ability to release gas except under overpressure conditions. A lift bag is a rubber enclosure with straps for underwater environments. Air is a common gas mixture injected into the bag via a compressed air shell. In some embodiments, the gas pressure inside the lift bag is greater than the surrounding underwater pressure. If the lift bag is equipped with a release valve, by operating the release valve, gas can escape from the lift bag through the valve into the surrounding water due to the pressure difference.

[0036] Overpressure, as used herein, describes the condition under which a lift pack is allowed to release air via a release valve to maintain the structural integrity of the lift pack. In situations where pressure release is not an option in the presence of lift (e.g., positive buoyancy), negative thrust is required to counteract the lift. Once ascent from lift begins, lift pack volume expansion occurs due to Boyle's law until a maximum amount of lift is reached (e.g., when drag prevents further increase in lift).

[0037] According to some embodiments, by slowly adjusting the SB lift and using a limited amount of thrust in the form of DB over time, energy consumption can be limited to a small amount compared to when only thrust is used to compensate for the increase in load or weight. For example, a control loop system can be used to provide a limited amount of DB via thrusters while using the SB generated by the lift packs to provide most of the buoyancy needed to offset the increase in load or weight.

[0038] According to some embodiments, Figure 2 2 is a schematic diagram of an exemplary antagonist / thrust device 200 configured to operate with a combination of SB and DB, SB and DB being generated by a lift pack 210 and a bidirectional reversible thruster 220 (hereinafter referred to as "thruster 220"), respectively. By way of example and not limitation, the antagonist / thrust device 200 may be used to control Figure 1 The buoyancy of the deep sea mining system 100 is shown. In some embodiments, the dynamic buoyancy system 160 may include a resistance / thrust device 200. In other embodiments, the variable load 230 may represent Figure 1 The payload hopper 150 is shown. In some embodiments, the propeller 220 can be used with Figure 1The UAV 130 is shown integrated, or may be a separate unit relative to the UAV 130.

[0039] In some embodiments, the lifting bag 210 is a rubber enclosure equipped with at least one gas valve 230 located at the base 210B of the rubber enclosure and one or more pressure relief valves 240 located at one or more side surfaces 210S. However, this is not restrictive, and the relief valve 240 may be placed in other suitable locations on the lifting bag (e.g., at the top surface or the bottom surface). According to some embodiments, the gas valve 230 is a one-way valve. This means that the gas valve 230 allows gas to be injected into the lifting bag 210, but prevents gas from escaping from the lifting bag 210. One or more gas cylinders 250 containing compressed gas (e.g., air or any other suitable gas mixture) provide gas to the lifting bag 210 via the gas valve 230. In some embodiments, the lifting bag 210 has an elliptical shape, wherein the long axis of the elliptical shape is along the vertical direction z, such as Figure 2 In other embodiments, the lifting bag 210 has a circular shape or any other suitable shape.

[0040] According to some embodiments, the thrusters 220 provide DB to mitigate overshoot events or second order effects by preventing or counteracting vertical displacement of the lift pack 210 when operating the lift pack 210, such as when gas is injected into or released from the lift pack 210. In some embodiments, the thrusters 220 may provide thrust in the x and y directions in addition to the z direction. In some embodiments, the thrusters 220 may be limited to providing thrust in the vertical direction z, while additional thrusters (in Figure 2 (not shown) can provide thrust in the x-direction and the y-direction.

[0041] Controlled descent and ascent in an opposition / thrust device

[0042] In some embodiments, power reduction during descent can be achieved by using lift to control the descent rate. For example, during descent, gas delivery can be adjusted so that the gas injected into the lift bag 210 reduces the rate at which the volume of the lift bag 210 contracts. The injection of gas in the lift bag 210 via valve 210B increases the gas pressure and offsets the volume compression caused by the increase in hydrostatic pressure. Therefore, by adjusting the amount of gas injected into the lift bag, the volume compression of the lift bag 210 can be controlled, thereby controlling the descent rate of the lift bag 210. In other words, as the countermeasure / thrust device 200 descends, the gas injection in the lift bag 210 can be increased at a rate that offsets the rate at which the volume of the lift bag 210 contracts due to the increase in hydrostatic pressure, so that the volume of the lift bag 210 contracts at a controlled rate. This will allow the countermeasure / thrust device 200 to descend at any desired rate without being affected by the hydrostatic pressure and avoiding overshoot events.

[0043] In some embodiments, a pressure sensor may provide a pressure reading of the hydrostatic pressure and a pressure reading of the gas inside the lift pack 210. Appropriate electronics (e.g., a controller) may then calculate the rate at which the pressure inside the lift pack increases as the hydrostatic pressure changes. Based on this information, gas injection may be adjusted to control the rate of descent. If appropriate gas delivery adjustments are made, overshoot may be prevented and thrust may be used only to enable recovery from second order effects. According to some embodiments, pressure compensated gas adjustments may be used for the gas supply to the lift pack 210 in the countermeasure / thrust device 200.

[0044] Similar concepts apply to ascent. For example, the ascent rate can be controlled by adjusting the release of gas via the pressure release valve 240. In some embodiments, the gas supply system can be responsible for operating the pressure release valve 240. In some embodiments, the same logic that operates the gas supply system can also operate the pressure release valve 240. In some embodiments, a system different from the gas supply system can operate the pressure release valve 240. As the buoyancy system rises and the volume of the lifting bag 210 increases, gas can be released via the release valve 240 at a rate comparable to the rate of volume increase to control the ascent rate. In some embodiments, the DB generated by the thruster 220 can be used to mitigate the impact of second-order effects.

[0045] Controlling neutral buoyancy in resistance / thrust devices

[0046] Ideally, the countermeasure / thrust device 200 enables the submersible vehicle (e.g., deep sea mining system 100) to remain in a neutrally buoyant state during ore collection. This means that the submersible vehicle is able to hover above the seafloor with minimal effort and without the need to generate large amounts of DB. To maintain neutral buoyancy, the lift pack 210 may be supplied with gas at frequent intervals (or as needed) to generate sufficient lift to offset the variable load 230. For example, as the weight of the variable load 230 increases, the onboard computer may calculate the amount of gas or air required to generate sufficient lift to offset the weight of the variable load 230 based on the hydrostatic pressure of the surrounding water. In some embodiments, the thrusters 220 may provide some amount of DB to prevent SB overshoot and eliminate any second order effects during gas injection.

[0047] According to some embodiments, onboard systems and probes can continuously collect data and dynamically calculate the amount of lift required to counteract the weight of the payload based on current hydrostatic pressure conditions. Based on this information, the appropriate amount of gas or air can be injected into the lift pack 210, while the thrusters 220 can intervene to make minor corrections or intervene if a problem is detected with the gas supply system of the countermeasure / thruster 200.

[0048] Other considerations and alternative use cases

[0049] According to some embodiments, multiple counteracting / thrusting devices may be used to control heavy weight lifting based on common control, common gas source, and common power source. Multiple points may reduce local thrust effects near the bottom of the water body, thereby providing less silt, reducing ecological disturbance, and allowing identification of items to be collected. Multiple counteracting / thrusting devices may be used to control heavy weight lifting, orientation and angle of the collection vehicle's payload, etc. by coordinating local pressure values ​​(e.g., using digital logic to control electric actuators such as solenoid valves).

[0050] For example, Figure 3 is a top view of a buoyancy system 300 equipped with four antagonism / thrust devices 200 attached to a variable load 310. Figure 3 In the example of FIG. 1 , each of the four counterforce / thrust devices 200 includes a lift package 210 and a thruster 220. It can be noted that the thruster 220 is Figure 3310 is not visible in the top view of the buoyancy system 300. In addition, the buoyancy system 300 may include additional components that are not shown for simplicity. These additional components may include, but are not limited to, one or more gas cylinders, electronic equipment, mechanical equipment, pneumatic equipment, etc. These additional components are within the spirit and scope of the present disclosure. By way of example and not limitation, the variable load 310 is depicted as having a rectangular shape. However, this is not limiting, and the variable load 310 may have any suitable shape - for example, square, circular, oval, etc. According to some embodiments, the buoyancy system 300 may be Figure 1 1. In other embodiments, each of the four antagonism / thrust devices 200 is configured in accordance with a combination of Figure 2 The buoyancy system 300 is provided with more or less than four antagonism / thrust devices 200, which are attached at suitable locations on the top or side surfaces of the variable load. For example, the buoyancy system 300 may include additional antagonism / thrust devices 200 of smaller size fixed at other locations on the variable load 310. It is understood that the antagonism / thrust devices 200 in the buoyancy system 300 may be operated independently of each other to allow for orientation and angle adjustment of the variable load 310 - for example, when an uneven distribution of weight occurs in the variable load 310.

[0051] A single counteracting / thrusting device can be used to move large diver-assisted or vehicle-assisted loads - for example, in commercial diving. A single counteracting / thrusting device can be used when the orientation (pitch and roll) of the load being lifted is not critical. Multiple thrusters will allow emergency recovery if a counteracting device fails.

[0052] The countermeasure / thrust device disclosed herein is not limited to deep sea operations or deep sea mining system 100. According to some embodiments, the energy efficient countermeasure / thrust device 200 may be used for any underwater activity related to lifting large loads and / or maintaining neutral buoyancy for long periods of time in an underwater vehicle or underwater object.

[0053] the term

[0054] The phraseology and terminology used herein is for the purpose of description only and should not be regarded as limiting.

[0055] As used in the specification and claims, the term "approximately", the phrase "approximately equal to" and other similar phrases (e.g., "X has a value of approximately Y" or "X is approximately equal to Y") should be understood to mean that one value (X) is within a predetermined range of another value (Y). Unless otherwise specified, the predetermined range may be plus or minus 20%, plus or minus 10%, plus or minus 5%, plus or minus 3%, plus or minus 1%, plus or minus 0.1%, or plus or minus 0.1% or less.

[0056] Unless expressly stated to the contrary, as used in the specification and claims, the indefinite articles "a" and "an" should be understood to mean "at least one". As used in the specification and claims, the phrase "and / or" should be understood to mean "either one or both" of the elements so combined, i.e., elements are present in combination in some cases and separately in other cases. Multiple elements listed with "and / or" should be interpreted in the same manner, i.e., "one or more" of the elements so combined. In addition to the elements specifically indicated by the "and / or" clause, other elements, whether related or unrelated to those specifically indicated, may optionally be present. Thus, as a non-limiting example, a reference to "A and / or B", when used in conjunction with open language such as "comprising", may refer to A only (optionally including elements other than B) in one embodiment; to B only (optionally including elements other than A) in another embodiment; to A and B (optionally including other elements) in yet another embodiment; and so on.

[0057] As used in the specification and claims, "or" should be understood to have the same meaning as "and / or" defined above. For example, when separating items in a list, "or" or "and / or" should be interpreted as being inclusive, i.e., including not only at least one of the list of elements or multiple elements, but also multiple of the list of elements or multiple elements, as well as optional additional unlisted items. Only terms that clearly indicate the opposite, such as "only one of" or "exactly one of", or "consisting of..." used in the claims, refer to exactly one element in the list of elements or multiple elements. Generally, the term "or" used should only be interpreted as indicating an exclusive choice (i.e., "one or the other, but not both") when it is preceded by an exclusive term such as "any one of", "one of", "only one of", or "exactly one of". "Mainly consisting of..." when used in the claims should have the ordinary meaning used in the field of patent law.

[0058] As used in the specification and claims, when referring to a list of one or more elements, the phrase "at least one" should be understood to mean at least one element selected from any one or more elements in the list of elements, but does not necessarily include at least one of each and every element specifically listed in the list of elements, nor does it exclude any combination of elements in the list of elements. This definition also allows that in addition to the elements specifically identified in the list of elements referred to by the phrase "at least one", other elements, whether related or unrelated to those elements specifically identified, may optionally be present. Thus, as a non-limiting example, “at least one of A and B” (or equivalently, “at least one of A or B”, or equivalently, “at least one of A and / or B”), in one embodiment, may refer to at least one A, at least one A optionally including more than one A, without the presence of B (and optionally including elements other than B); in another embodiment, may refer to at least one B, at least one B optionally including more than one B, without the presence of A (and optionally including elements other than A); in yet another embodiment, may refer to at least one A and at least one B, at least one A optionally including more than one A, at least one B optionally including more than one B (and optionally including other elements); and so on.

[0059] The use of "including," "comprising," "having," "including," "involving," and variations thereof, is meant to encompass the items listed thereafter as well as additional items.

[0060] The use of ordinal numbers such as "first", "second", "third", etc. in the claims to modify claim elements does not, by itself, indicate any priority, precedence, or order of one claim element over another claim element, nor does it indicate a temporal order in which the acts of performing the method are performed. Ordinal numbers are used only as labels to distinguish one claim element having a particular name from another element having the same name (but using an ordinal number), thereby distinguishing the claim elements.

[0061] Having thus described several aspects of at least one embodiment of the present invention, it will be appreciated that various changes, modifications and improvements will be readily made by those skilled in the art. Such changes, modifications and improvements are intended to be a part of this disclosure and are intended to be within the spirit and scope of the present invention. Therefore, the above description and accompanying drawings are intended only as examples.

Claims

1. A device comprising: an antagonist configured to provide static buoyancy to the device when the device is underwater, the antagonist comprising a gas valve and a release valve; a thruster coupled to the countermeasure, the thruster configured to provide dynamic buoyancy to the device when the device is underwater; Variable load; as well as A gas supply system comprising a gas cylinder connected to the gas valve of the antagonist, wherein the gas supply system is configured to inject a predetermined amount of gas from the gas cylinder into the antagonist via the gas valve in response to a change in the vertical position of the antagonist caused by a change in the mass of the variable load.

2. The device according to claim 1, wherein: The gas supply system is further configured to operate the release valve to release gas from the antagonist in response to another change in the vertical position of the antagonist caused by a change in the mass of the variable load.

3. The device according to claim 2, wherein: The change is a downward change in the vertical position of the antagonist, and the other change is an upward change in the vertical position of the antagonist.

4. The device according to claim 1, wherein: The antagonist is a boost pack.

5. The device according to claim 1, wherein: The gas is a gas mixture.

6. The device according to claim 5, wherein: The gas mixture is air.

7. The device according to claim 1, wherein: The thruster is configured to provide an upward thrust or a downward thrust when the gas supply system injects gas into the antagonist.

8. The device according to claim 1, wherein: The thruster is a bidirectional reversible thruster.

9. The device according to claim 1, wherein: The gas supply system operates with pressure-compensated gas regulation.

10. The device according to claim 1, wherein: The predetermined amount of gas is based on a change in mass of the variable load and a hydrostatic pressure of water surrounding the antagonist.

11. The device according to claim 1, wherein: The gas valve is a one-way valve arranged at a base of the antagonist, and the release valve is arranged on a side surface of the antagonist.

12. A method for maintaining neutral buoyancy of an underwater vehicle under variable load conditions, the method comprising: varying the mass of a variable load attached to the underwater vehicle; generating lift using an inflatable lift bag attached to the underwater vehicle by injecting an amount of gas into the inflatable lift bag in response to changing the mass of the variable load, wherein the amount of gas injected is based on the change in mass of the variable load and the hydrostatic pressure of water surrounding the lift bag; as well as As the gas is injected, a certain amount of thrust is applied to oppose the change in the vertical position of the underwater vehicle until the lift generated by the injected amount of gas becomes stable.

13. The method according to claim 12, wherein: Injecting the amount of gas into the inflatable lift bag includes injecting gas from a gas cylinder attached to the underwater vehicle via a one-way valve disposed at a bottom surface of the inflatable bag.

14. The method according to claim 12, wherein: Applying thrust includes operating a bi-directionally reversible thruster attached to the underwater vehicle.

15. The method according to claim 12, wherein: Changing the mass of the variable load includes increasing the mass of the variable load.

16. The method according to claim 12, wherein: Generating lift includes generating static buoyancy.

17. The method according to claim 12, wherein: Applying thrust includes generating dynamic buoyancy.

18. The method according to claim 12, wherein: Injecting the amount of gas into the expandable lift bag includes injecting a gas mixture into the expandable lift bag.

19. The method according to claim 18, wherein: The gas mixture is air.

20. The method according to claim 12, wherein: The lift force generated becomes stable after about 30 seconds or less.

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