Autonomous underwater drone and method for manufacturing such a drone

Abstract

The invention relates to an autonomous underwater drone (1) and to a method for manufacturing such an autonomous underwater drone (1) comprising a step of assembling a body (2) comprising at least a battery (3) and an electronic device (4) powered by the battery (3), a step of inserting the body (2) into a mould comprising two mould cavities, a moulding cavity being formed between the two mould cavities and the body (2). The method also comprises a step of overmoulding the body (2) in which the moulding cavity is filled with a liquid polymer material, a demoulding step carried out after curing the polymer material in order to obtain an autonomous underwater drone (1) comprising a hull (8) overmoulded around the body (2), and a step of mounting at least one thruster (25a, 25b, 25c, 25d) on the hull (8).

Description

Autonomous underwater drone and method of manufacturing such a drone

[0001] The invention relates to an autonomous underwater drone and to a method of manufacturing such an autonomous underwater drone.

[0002] Autonomous underwater drones, commonly referred to as AUVs (an acronym for the English term "Autonomous Underwater Vehicle"), are used to explore the seabed and collect physicochemical data, for example to image the Earth's crust under the seabed for geophysical purposes.

[0003] Autonomous underwater drones generally include one or more waterproof enclosures in which various electronic and electrical components are integrated, such as, for example, the thruster motors, the battery, the power management device, the computers and the means of communication.

[0004] These enclosures must be completely watertight and maintain this seal at high pressures in the deep sea or at low but cycled pressures on the surface, i.e. varying regularly.

[0005] The production of these enclosures for deep sea requires a high level of control over the quality of the joint surfaces and their deformation under pressure. Furthermore, to avoid problems related to pressure cycling and to monitor the quality of the seal, the majority of enclosures are placed under vacuum when they are closed to keep the seals, often O-rings, in the operating position.

[0006] Power and signal wires run through high-performance, expensive underwater connectors that require precise machining to ensure a watertight seal.

[0007] The manufacturing of these autonomous underwater drones is therefore complex. Furthermore, the solutions used to achieve waterproofing represent a significant portion of the cost of an autonomous underwater drone.

[0008] Therefore, users are looking to make their autonomous underwater drones as modular as possible by planning to mount different payloads on the drone, such as seismic sensors, for example. To maximize their profitability, users mount these payloads on the drones, the cost of which can exceed that of the drone itself. Therefore, the more expensive the waterproof enclosure, the more the user has an incentive to mount expensive payloads to maximize their investment.

[0009] In addition, some users implement a large number of autonomous underwater drones in the seabed, up to a few thousand, to form large swarms that are very effective in collecting physicochemical data, which entails a very high cost.

[0010] The aim of the invention is therefore to overcome the drawbacks of the prior art by proposing a lower-cost autonomous underwater drone with improved sealing and suitable for deep seabeds and cyclical surface use, as well as a method for manufacturing such a simplified autonomous underwater drone.

[0011] To this end, the invention thus relates, in its broadest sense, to an autonomous underwater drone comprising an integral hull and a body comprising at least one battery and an electronic device powered by the battery, the body being encompassed by the hull.

[0012] The invention thus provides a low-cost autonomous underwater drone with waterproofing suitable for deep seas and cyclic surface use.

[0013] The overmolded shell perfectly isolates the drone's internal components, such as the battery and electronic systems, from the marine environment, avoiding the use of gaskets, penetrators, and cable glands. The shell allows for the creation and stiffening of connections between the elements of the block.

[0014] The invention makes it possible to avoid using enclosures whose hermetic insulation is complex to implement.

[0015] In fact, the hull simply performs several functions that were previously performed by a large number of parts assembled together in prior art drones, such as hydrodynamics and the maintenance of internal and external components, such as the thrusters, electronic cards, sensors and the acoustic head, for example.

[0016] The autonomous underwater drone can reach depths of 450 m, or even several thousand meters.

[0017] The invention makes it possible to offer highly specialized autonomous underwater drones, i.e., drones incorporating functionalities adapted to a specific mission, such as the search for hydrocarbons, for example. This makes it possible to significantly reduce their cost by adapting their functionalities as precisely as possible. Only the components or sensors necessary for a specific mission are included in the autonomous underwater drone. Since manufacturing costs are reduced, a user can operate a fleet of highly specialized autonomous underwater drones also at a lower cost.

[0018] According to another variant, the polymer material is based on polyurethane.

[0019] One advantage is that corrosion has little effect on polyurethane. Another advantage is that a thickness of a few centimeters, for example between 1 cm and 5 cm, of polyurethane helps limit hydrostatic pressure on the overmolded body components and allows the autonomous underwater drone to reach depths of around 1000 m.

[0020] According to another embodiment, the autonomous underwater drone comprises at least a first recess formed in the hull. A first thruster is fixed in the first recess and connected to a first set of connecting wires of the body.

[0021] According to another variant, the autonomous underwater drone comprises an electronic compartment opening from the hull through an opening delimited by a fixing support covered by the polymer material so as to form a border of polymer material on the fixing support. A closing element is fixed on the border to close the opening in a watertight and removable manner.

[0022] The electronics compartment is a "dry" area allowing the installation of electronic components still under development and the drone's reprogramming connectors. Thanks to the properties of polyurethane, creating such a pressure-resistant compartment is simple.

[0023] This allows access to an electronic card located in the electronic compartment and requiring reprogramming. The sealing element is removable and can be opened to reprogram the electronic card. It is then closed tightly.

[0024] According to another variant, the autonomous underwater drone comprises a removable element covered by a layer of intermediate material. The intermediate material is covered by the polymer material.

[0025] This solution makes it easy to replace a removable element such as a battery, for example.

[0026] The invention also relates to a method of manufacturing an autonomous underwater drone.

[0027] According to the invention, the manufacturing method comprises a step of assembling a body comprising at least one battery and an electronic device powered by the battery and a step of inserting the body into a mold comprising a first imprint and a second imprint. A cavity is formed between the two imprints and the body.

[0028] Alternatively, the mold may include more than two cavities to overmold the shell.

[0029] Alternatively, the mold can integrate multiple bodies and include multiple cavities to manufacture multiple autonomous underwater drones.

[0030] The manufacturing method also includes a step of overmolding the body in which the cavity is filled with a liquid polymer material and a demolding step carried out after hardening of the polymer material to obtain an autonomous underwater drone comprising a hull overmolded around the body.

[0031] The manufacturing process finally includes a step of mounting at least one thruster on the hull.

[0032] The invention thus provides a method for manufacturing a simplified autonomous underwater drone, making it possible to obtain a lower-cost autonomous underwater drone with a seal suitable for deep seabeds and cyclic surface use.

[0033] The overmolded hull perfectly isolates the drone's internal components, such as the battery and electronic systems, from the marine environment, eliminating the need for gaskets, penetrators, and cable glands. The hull stiffens the connections between the unit's components.

[0034] The overmolding process eliminates the need for enclosures whose hermetic insulation is complex to implement. With the invention, this insulation is achieved in a single overmolding step. Manufacturing time and costs are thus significantly reduced.

[0035] In fact, the hull simply performs several functions that were previously performed by a large number of parts assembled together in prior art drones, such as hydrodynamics and the maintenance of internal and external components, such as the thrusters, electronic cards, sensors and the acoustic head, for example.

[0036] The autonomous underwater drone can reach depths of 450 m, or even several thousand meters.

[0037] The overmolding process allows for the manufacture of highly specialized autonomous underwater drones, i.e., those incorporating features adapted to a specific mission, such as hydrocarbon research, for example. This significantly reduces their cost by adapting their features as closely as possible. Only the components or sensors necessary for a specific mission are included in the autonomous underwater drone. Because manufacturing costs are reduced, a user can operate a fleet of highly specialized autonomous underwater drones at a lower cost.

[0038] According to one variant, the impressions comprise at least a first protruding element to form a first recess in the shell.

[0039] This allows the integration of thrusters, sensors, cooling elements or a cooling zone, for example.

[0040] According to another variant, a masking element is formed around one end of at least a first set of connection wires of the body during the body assembly step. The liquid polymer material is flush with the masking element during the overmolding step. The masking element is removed after the demolding step. The first set of connection wires is connected to a second set of connection wires of a component external to the shell. An additional overmolding operation is carried out around a connection area formed by the connection of the first set of connection wires with the second set of connection wires to encompass the connection area with polymer material and ensure its sealing.

[0041] This process allows external components to be electrically connected to the block's electronic device and assembled to the shell after molding, in a simple manner.

[0042] According to another variant, the autonomous underwater drone comprises an electronic compartment opening from the hull through an opening delimited by a fixing support covered by the polymer material during the overmolding step so as to form a border of polymer material on the fixing support. A sealing element is fixed on the border after the demolding step to close the opening in a sealed and removable manner.

[0043] This process allows for a "dry" area to be created, allowing for the insertion of electronic components that are still being developed and the drone's reprogramming connectors. Thanks to the properties of polyurethane, creating such a pressure-resistant compartment is simple.

[0044] This allows access to an electronic card located in the electronic compartment and requiring reprogramming. The sealing element is removable and can be opened to reprogram the electronic card. It is then closed tightly.

[0045] The removable shutter element also allows memory media to be retrieved from the electronics compartment to collect recorded data.

[0046] According to another variant, reinforcement elements are positioned in the body during the assembly stage. These reinforcement elements make it possible to reinforce the resistance of the autonomous underwater drone or certain "dry" areas which are at atmospheric pressure, such as the electronics compartment, for example.

[0047] According to another variant, the body comprises a removable element which is covered by a layer of intermediate material before the overmolding step. The intermediate material is covered by the polymer material during the overmolding step.

[0048] The intermediate material is easily removable to facilitate removal of the removable element.

[0049] According to another variant, marking counterforms are provided in the impressions to form markings on the shell by the marking counterforms, around the removable element, during the overmolding step.

[0050] This solution makes it easy to identify the areas to be cut.

[0051] The invention also relates to a method of replacing a removable element of an autonomous underwater drone. The body comprises a first removable element covered by a first layer of intermediate material positioned between the first removable element and an outer layer.

[0052] According to the invention, the replacement method comprises a first step in which the outer layer is cut and removed, a second step in which the first layer of intermediate material is removed, a third step in which the first removable element is replaced by a second removable element and a fifth step in which the second removable element is covered by an additional layer of polymer material.

[0053] According to a variant, the replacement method comprises a fourth step in which the second removable element is covered by a second layer of intermediate material before the fifth step of covering by the additional layer of polymer material. The second layer of intermediate material is positioned between the second removable element and the additional layer of polymer material.

[0054] The disassembly process provides a simple and low-cost solution for changing a component of the autonomous underwater drone, without losing its waterproofing.

[0055] Embodiments of the present invention will be described below, by way of non-limiting examples, with reference to the appended figures in which:

[0056] schematically illustrates a perspective view of an autonomous underwater drone obtained by a manufacturing method, according to an embodiment of the invention;

[0057] schematically illustrates a body of the autonomous underwater drone of the;

[0058] schematically illustrates the body inserted into a mold during an overmolding step;

[0059] schematically illustrates a masking element formed around one end of at least a first set of connecting wires of the body;

[0060] schematically illustrates a longitudinal sectional view of the autonomous underwater drone of the;

[0061] schematically illustrates the detail of an electronic compartment of the;

[0062] schematically illustrates a view from below of the autonomous underwater drone of the;

[0063] schematically illustrates a method of replacing a removable element of the autonomous underwater drone.

[0064] The invention relates to a method of manufacturing an autonomous underwater drone 1, as illustrated in the.

[0065] The autonomous underwater drone 1, conventionally called AUV (acronym for the English term “Autonomous Underwater Vehicle”), is used to explore the seabed and record physicochemical data to image, for example, the Earth’s crust under the seabed for geophysical purposes.

[0066] The autonomous underwater drone 1 comprises a body 2, as illustrated in the, comprising a battery 3, an electronic device 4 powered by the battery 3 and controlling, among other things, a propulsion system.

[0067] According to this embodiment, the body 2 also comprises a buoyancy element 5 which may be made of foam, such as an epoxy structural foam, or a glass sphere, for example.

[0068] The drone has a reference point in space comprising a longitudinal axis X following a direction of advancement of said autonomous underwater drone 1, a transverse axis Y perpendicular to the longitudinal axis X and a vertical axis Z, perpendicular to the longitudinal axis X and to the transverse axis Y.

[0069] The buoyancy element 5 and the autonomous underwater drone 1 extend along the longitudinal axis X.

[0070] According to a variant, the buoyancy element 5 and the autonomous underwater drone 1 can extend mainly along the vertical axis Z to perform an elevator function towards the surface, for example.

[0071] The body 2 may comprise a base plate 27 on which the battery 3 and the electronic device 4 are fixed. The buoyancy element 5 is fixed to the battery 3. The base plate 27 may have a radiator function to dissipate the calories from the battery 3.

[0072] The propulsion system comprises several thrusters 25a, 25b, 25c, 25d including two horizontal thrusters 25c, 25d positioned at a rear part 43 of the autonomous underwater drone 1 and making it possible to move the autonomous underwater drone 1 forward along the longitudinal axis X.

[0073] The propulsion system also comprises two vertical thrusters 25a, 25b, including a first vertical thruster 25a positioned at the front portion 44 of the autonomous underwater drone 1 and a second vertical thruster 25b positioned at a rear portion 43 of the autonomous underwater drone 1. The vertical thrusters 25a, 25b may be configured to stabilize or tilt the autonomous underwater drone 1 and / or raise the autonomous underwater drone 1 from the seabed.

[0074] Each thruster 25a, 25b, 25c, 25d may comprise one or more propellers 26 and a motor powered by the battery 3 to drive the propeller 26.

[0075] The thrusters 25a, 25b, 25c, 25d may comprise a brushless motor (also referred to as the English term "brushless"), without a cavity containing air or liquid such as oil. The brushless motor is submerged in water, operating at isopressure with the aquatic environment. This motor is therefore insensitive to the aquatic environment. The motor may be a "Blue Robotics T200" motor ("registered trademark").

[0076] This motor is pressure-resistant and eliminates the need for sealed enclosures.

[0077] Alternatively, other propulsion systems can be used, such as jets or pumps, for example.

[0078] A robust pressure-resistant 3 battery that eliminates the need for waterproof enclosures can also be used as a molded battery pack of the "SeaPower" type ("registered trademark") from Kraken Robotics ("registered trademark") which uses lithium-polymer technology.

[0079] The battery 3 is positioned approximately in the center of the autonomous underwater drone 1, between the two vertical thrusters 25a, 25b and at a lower part 30 of the autonomous underwater drone 1.

[0080] The terms “lower” and “upper” will be understood according to their usual definition, in which the term “lower” indicates a greater proximity to the ground along the vertical Z axis than the term “upper” when the autonomous underwater drone 1 is in normal operating condition.

[0081] Alternatively, the propulsion system may include adjustable wings to control a trajectory of the autonomous underwater drone 1.

[0082] The autonomous underwater drone 1 may also include an inertial navigation system (INS) configured to guide the autonomous underwater drone 1 to a desired location. An inertial navigation system may include a module containing accelerometers, gyroscopes, magnetometers, or other motion-sensing devices.

[0083] The INS may initially receive the actual position and speed of the autonomous underwater drone 1 from another source, such as a human operator, a GPS satellite receiver, a deployed underwater station, another autonomous underwater drone 1, from the vessel. The INS calculates its own updated position and speed by integrating the information received from motion sensors.

[0084] Other alternative systems may be used, such as, for example, an acoustic Doppler system for acoustic positioning. Sound waves bouncing off the seabed may be used to determine the speed of the autonomous underwater drone 1, which combined with a position fix, a compass heading, and data from various sensors of the autonomous underwater drone 1, allow the position of the autonomous underwater drone 1 to be determined.

[0085] Alternatively, the autonomous underwater drone 1 may include a compass and other sensors such as, for example, an altimeter for measuring its altitude or a pressure gauge. The autonomous underwater drone 1 may optionally include an obstacle avoidance system and a Wi-Fi communication device or another wireless interface, such as a device that uses an acoustic link, for example. These elements may be connected to the electronic device 4.

[0086] The autonomous underwater drone 1 may further comprise an antenna that may be flush with or protrude from the body 2 of the autonomous underwater drone 1 by being integrated into a protrusion 28. The autonomous underwater drone 1 may comprise an acoustic system for underwater communications with an underwater station, another autonomous underwater drone 1, or a surface vessel and positioning the autonomous underwater drone 1.

[0087] The acoustic system can be a USBL system (acronym for the English term “Ultra-Short Baseline”), for example.

[0088] The manufacturing process of the autonomous underwater drone 1 comprises a step of assembling the body 2 illustrated on the and presented previously.

[0089] The elements of the body 2 such as the buoyancy element 5, the base plate 27, the battery 3 and the electronic device 4 may be bonded together by gluing or double-sided adhesive, for example. These elements are weakly bonded so as only to hold them together during a subsequent overmolding operation. These elements are then strongly and permanently bonded after overmolding.

[0090] The manufacturing method comprises a step of inserting the body 2 into a mold 7 comprising a first impression 9 and a second impression 10, as illustrated in the.

[0091] The first and second impressions 9, 10 may be made of elastomer, such as silicone for example, or polymer, such as polytetrafluoroethylene (PTFE) for example, or metal, such as aluminum or steel for example.

[0092] A cavity 6 is formed between the first and second impressions 9, 10 and the body 2.

[0093] The manufacturing method comprises an overmolding step during which the cavity 6 is filled with a liquid polymer material. The liquid polymer material is poured by gravity or under vacuum into an orifice 39 formed in the mold 7.

[0094] Alternatively, the overmolding may be carried out by a low-pressure injection process into a mold or by successive dipping of the polymer material or by a combination of several steps. A first step of molding the body 2 with concrete may be provided and followed by a second step of molding with the polymer material, for example.

[0095] After polymerization and therefore hardening of the liquid polymer material, the mold 7 is opened, during a demolding step, to obtain an autonomous underwater drone 1 comprising an integral shell 8 overmolded around the body 2, as illustrated in Figures 1 and 5. An integral shell 8 means that the shell 8 is formed from a single block (monobloc), without joints. The integral shell 8 does not have gaps or discontinuities. The integral shell 8 forms a single piece having a continuous outer surface.

[0096] The hull 8 is then deburred.

[0097] The thickness of the shell 8 is between 1 cm and 5 cm. For this, the distance between the two impressions 9, 10 and the body 2 is between 1 cm and 5 cm.

[0098] Preferably, the liquid polymer material is polyurethane (PU). The advantage is that corrosion has little effect on polyurethane. In addition, the advantage of using silicone prints 9, 10 is that it does not stick to polyurethane.

[0099] A thickness of a few centimeters of polyurethane limits the hydrostatic pressure on the overmolded components of the body 2 and allows the autonomous underwater drone 1 to reach depths of around 1000 m.

[0100] Other polymers or elastomers, whether or not loaded, can be used. By loading the polymer material with “light” elements, i.e. elements having a density lower than that of water, such as glass microbeads, for example, the shell 8 then becomes buoyant and makes it possible to dispense with the buoyancy element 5.

[0101] The polymer material can also be loaded with metal to, on the contrary, make the autonomous underwater drone 1 heavier.

[0102] The cavities 9, 10 of the mold 7 comprise at least one first protruding element 46 to form at least one first recess 47a in the shell 8 intended to receive the first vertical propellant 25a.

[0103] Preferably, the cavities 9, 10 of the mold 7 comprise a second protruding element for forming a second recess 47b in the shell 8 intended to receive the second propellant 25b, a third protruding element for forming a third recess 47c in the shell 8 intended to receive the third propellant 25c and a fourth protruding element for forming a fourth recess 47d in the shell 8 intended to receive the fourth propellant 25d.

[0104] As illustrated in the, the base plate 27 is not entirely coated by the polymer material to allow it to perform a radiator function and dissipate the calories from the battery 3.

[0105] The first impression 9 comprises a fifth projecting element making it possible to obtain a fifth recess 29 on the lower part 30 of the autonomous underwater drone 1. The fifth recess 29 forms an area not covered by the polymer material on the lower part 30 of the autonomous underwater drone 1 during the overmolding step.

[0106] The body 2 also comprises the protuberance 28, described previously and positioned at an upper part 45 of the autonomous underwater drone 1, which can house an acoustic system for communication or a sonar or measuring instruments for mapping the seabed, for example.

[0107] The protrusion 28 is not covered by the polymer material during overmolding.

[0108] The autonomous underwater drone 1 comprises an electronic compartment 16 opening from the hull 8 through an opening 17, as illustrated in Figures 5 and 6.

[0109] The body 2 also comprises a fixing bracket 31 positioned at the upper part 45 of the autonomous underwater drone 1. The fixing bracket 31 is covered by the polymer material so as to form a border 36 of polymer material on the fixing bracket 31.

[0110] The protrusion 28 and the fixing support 31 are positioned between the two vertical thrusters 25a, 25b.

[0111] The mounting bracket 31 comprises studs 37 which are not covered by the polymer material.

[0112] The fixing support 31 and the edge 36 have a circular section and delimit the opening 17.

[0113] The second cavity 10 of the mold 7 comprises a sixth protruding element 48 to form a sixth recess 49 in the shell 8. The electronic compartment 16 is positioned in the sixth recess 49.

[0114] A sealing element 18 is fixed to the edge 36 to close the opening 17 in a sealed and removable manner, after the demolding step. The sealing element 18 is in the form of a dome, for example. The studs or screws 37 are inserted into holes provided in a collar 38 of the sealing element 18. Nuts are screwed onto the studs to lock the sealing element 18 onto the edge 36.

[0115] The electronic compartment 16 comprises at least one removable electronic device 32 which may be a memory medium such as a hard disk or an SD card or an electronic card, for example.

[0116] The electronic card needs to be reprogrammed. The sealing element 18 is removable and can be opened to reprogram the electronic card. It is then closed tightly.

[0117] The removable shutter element 18 also makes it possible to retrieve the memory media in the electronic compartment 16 to collect the recorded data.

[0118] The electronic compartment 16 is housed in an orifice 33 provided in the buoyancy element 5.

[0119] Reinforcing elements 19a, 19b (or pressure recovery elements) are positioned in the body 2 during the assembly step.

[0120] A first reinforcing element 19a is provided to delimit the electronic compartment 16. The first reinforcing element 19a has a cylindrical shape and is made of metal, for example. The first reinforcing element 19a extends along the vertical axis Z. The first reinforcing element 19a makes it possible to protect the memory medium 32.

[0121] The body 2 comprises a second reinforcing element 19b positioned opposite a lower end 34 of the electronic compartment 16, positioned opposite the opening 17.

[0122] The second reinforcing element 19b may be a metal plate of circular or quadrilateral section, for example.

[0123] Alternatively, a masking element 11 is formed around one end 12 of at least a first set of connecting wires 13 of the body 2 during the step of assembling the body 2, as illustrated in the.

[0124] Preferably, the masking element 11 is made of silicone. The masking element 11 is molded around the end 12 of the first set of connecting wires 13. The first set of connecting wires 13 comprises two or three electrical wires 35.

[0125] The first and second cavities 9, 10 of the mold 7 are configured so that the liquid polymer material is flush with the masking element 11 so as not to encompass the masking element 11 during the step of overmolding the cavity 6. In the mold 7, the masking element 11 is positioned outside the cavity 6 so as not to be encompassed by the liquid polymer material.

[0126] The masking element 11 is removed after the demolding step to leave the end 12 of the first set of connecting wires 13 accessible.

[0127] The first set of connection wires 13 is then connected to a second set of connection wires of an external component 14a, 14b, 14c, 14d intended to be fixed to the hull 8, such as a thruster 25a, 25b, 25c, 25d, for example.

[0128] In the example of Figures 1 to 7, the autonomous underwater drone 1 comprises two horizontal thrusters 25c, 25d and two vertical thrusters 25a, 25b, as described previously. The autonomous underwater drone 1 therefore comprises four first sets of connection wires 13 initially masked by four masking elements 11. The four masking elements 11 are then connected to four separate thrusters 25a, 25b, 25c, 25d.

[0129] The first sets of connecting wires 13 are connected to a control device of the ESC type (acronym for the English term Electronic Speed ​​Controller) mounted in the body 2.

[0130] The first and second sets of connecting wires 13 are connected by soldering, for example. Alternatively, the first and second sets of connecting wires 13 may be connected by means of a connector.

[0131] An additional overmolding operation is then performed around a connection area 15 formed by connecting the first set of connection wires 13 with the second set of connection wires to encompass the connection area 15 with additional polymer material.

[0132] The additional polymer material is preferably of the same nature as that used during the overmolding step but of a different color to be able to identify it during a subsequent replacement operation of the propellants 25a, 25b, 25c, 25d. It is then possible to remove only the additional polymer material.

[0133] Alternatively, the body 2 comprises a removable (or interchangeable) element 20. For example, the battery 3 is a removable element 20 in the example of Figures 1 to 7.

[0134] The removable element 20 is covered (or encompassed) by a layer of intermediate material 21 before the overmolding step. The intermediate material 21 is an easily removable material to facilitate the replacement of the removable element 20. The intermediate material 21 may be a friable material, such as silicone, low shore hardness polyurethane or wax, for example.

[0135] The intermediate material 21 is then covered by the polymer material during the overmolding step.

[0136] Alternatively, when the body 2 comprises a base plate 27 and an area not covered by the polymer material such as the fifth recess 29, it is the base plate 27 which is partially covered by the polymer material, as illustrated in the.

[0137] Alternatively, marking counterforms are provided in the imprints 9, 10 to form markings 22a, 22b outside the shell 8, around the removable element 20 and the area not covered by the polymer material, during the overmolding step.

[0138] The shell 8 may comprise two oblong-shaped markings 22a, 22b positioned opposite each other, and on either side of the area not covered by the polymer material.

[0139] A first pre-cut 40 and a second pre-cut 41 are provided in the base plate 27 to facilitate its cutting. The first and second pre-cuts 40, 41 are positioned opposite each other.

[0140] The manufacturing method of the invention makes it possible to obtain an autonomous underwater drone 1 of the order of 2 kg in water, i.e. of the order of 15 kg in the air, capable of landing on the seabed to acquire acoustic data. The autonomous underwater drone 1 has a length of approximately 500 mm, a width of 300 mm and a height of 300 mm, for example.

[0141] The autonomous underwater drone 1 carries an acoustic positioning system, such as a “SEAKER +” system (registered trademark) from the company “ARKEOCEAN” (registered trademark) for example, and a device recording the ambient acoustic noise captured by a hydrophone. The acoustic positioning system and the hydrophone can be housed in the protuberance 28.

[0142] The autonomous underwater drone 1 has enough autonomy to navigate a few kilometers at a maximum speed of 3 knots.

[0143] The invention also relates to a method of replacing a removable element 20, as illustrated in the.

[0144] For example, when the removable element 20 is a battery 3, it may be advantageous to be able to replace it with a new battery 3 after several recharge / discharge cycles.

[0145] According to a variant, the body 2 comprises a first removable element 20a covered or encompassed by a first layer of intermediate material 21a positioned between the first removable element 20a and an external layer 42. The external layer 42 may be made of polymer material or the base plate 27.

[0146] The replacement method comprises a first step A in which the outer layer 42, positioned opposite the first removable element 20a, is cut and removed. The outer layer 42 is delimited by the markings 22a, 22b and the two pre-cuts 40, 41 to easily identify the hard areas to be cut.

[0147] The replacement method comprises a second step B in which the first layer of intermediate material 21a is removed and a third step C in which the first removable element 20a is replaced by a second removable element 20b.

[0148] The replacement method comprises a fourth step D in which the second removable element 20b is covered or encompassed by a second layer of intermediate material 21b and a fifth step E in which the second removable element 20b is covered or encompassed by an additional layer of polymer material 24.

[0149] The second layer of intermediate material 21b is positioned between the second removable element 20b and the additional layer of polymer material 24.

[0150] Thus, it will be possible to replace the second removable element 20b again thanks to the second layer of intermediate material 21b which is easily removable.

[0151] The first and second layers of intermediate material 21a, 21b have a lower hardness than that of the shell 8 and the additional polymeric material layer 24. The first and second layers of intermediate material 21a, 21b may be based on a friable or soft material, as described above, or be fused.

[0152] Alternatively, if the replacement of the second removable element 20b is not envisaged, it is possible to simplify the method by removing the fourth step D in which the second removable element 20b is covered by a second layer of intermediate material 21b.

[0153] The second removable element 20b is then directly covered or enclosed by the additional layer of polymer material 24.

[0154] Alternatively, the first and second layers of intermediate material 21a, 21b may be functional layers. They may be based on a thermally conductive material, such as an epoxy-based conductive resin, to extract heat from the battery 3 or the ESC-type control device, for example.

[0155] Alternatively, the first and second layers of intermediate material 21a, 21b may be based on a material improving pressure resistance.

[0156] Alternatively, the first and second layers of intermediate material 21a, 21b may be based on concrete or clay to add mass to the autonomous underwater drone 1 to be able to position it on the seabed or add stability to it.

Claims

Autonomous underwater drone (1) characterized in that it comprises an integral hull (8) forming a single piece having a continuous exterior surface and a body (2) forming a block of components linked together by rigid connections comprising at least one battery (3) and an electronic device (4) powered by the battery (3), the body (2) being encompassed by the hull (8). Autonomous underwater drone (1) according to claim 1, characterized in that the hull (8) is a hull (8) overmolded by a polymer material around the body (2). Autonomous underwater drone (1) according to claim 2, characterized in that the polymer material is based on polyurethane. Autonomous underwater drone (1) according to any one of claims 1 to 3, characterized in that it comprises at least a first recess (47a) formed in the hull (8), a first thruster (25a) being fixed in the first recess (47) and connected to a first set of connection wires (13) of the body (2). Autonomous underwater drone (1) according to any one of claims 2 to 4, characterized in that it comprises an electronic compartment (16) opening from the hull (8) through an opening (17) delimited by a fixing support (31) covered by the polymer material so as to form a border (36) of polymer material on the fixing support (31), a closing element (18) being fixed on the border (36) to close the opening (17) in a sealed and removable manner. Autonomous underwater drone (1) according to any one of claims 2 to 5, characterized in that it comprises a removable element (20) covered by a layer of intermediate material (21), the intermediate material (21) being covered by the polymer material. A method of manufacturing an autonomous underwater drone (1), characterized in that it comprises: a step of assembling a body (2) forming a block of components comprising at least one battery (3) and an electronic device (4) powered by the battery (3), a step of inserting the body (2) into a mold (7) comprising a first imprint (9) and a second imprint (10), a cavity (6) being formed between the two imprints (9, 10) and the body (2), a step of overmolding the body (2) in which the cavity (6) is filled with a liquid polymer material, a demolding step carried out after hardening of the polymer material to obtain an autonomous underwater drone (1) comprising a hull (8) overmolded around the body (2) forming a block of components linked together by rigid connections, and a step of mounting at least one thruster (25a, 25b, 25c, 25d) on the hull (8). Manufacturing method according to claim 7, characterized in that the impressions (9, 10) comprise at least a first protruding element (46) to form a first recess (47a) in the shell (8). Manufacturing method according to any one of claims 7 or 8, characterized in that a masking element (11) is formed around one end (12) of at least a first set of connection wires (13) of the body (2) during the step of assembling the body (2), the liquid polymer material being flush with the masking element (11) during the overmolding step, the masking element (11) being removed after the demolding step, the first set of connection wires (13) being connected to a second set of connection wires of an external component (14a, 14b, 14c, 14d) to the shell (8), an additional overmolding operation being carried out around a connection zone (15) formed by the connection of the first set of connection wires (13) with the second set of connection wires to encompass the connection zone (15) with polymer material and ensure its sealing. Manufacturing method according to any one of claims 7 to 9, characterized in that the autonomous underwater drone (1) comprises an electronic compartment (16) opening from the hull (8) through an opening (17) delimited by a fixing support (31) covered by the polymer material during the overmolding step so as to form a border (36) of polymer material on the fixing support (31), a closing element (18) being fixed on the border (36) after the demolding step to close the opening (17) in a sealed and removable manner. Manufacturing method according to any one of claims 7 to 10, characterized in that reinforcing elements (19a, 19b) are positioned in the body (2) during the assembly step. Manufacturing method according to any one of claims 7 to 11, characterized in that the body (2) comprises a removable element (20), the removable element (20) being covered by a layer of intermediate material (21) before the overmolding step, the intermediate material (21) being covered by the polymer material during the overmolding step. Manufacturing method according to claim 12, characterized in that marking counterforms are provided in the imprints (9, 10) to form markings (22a, 22b) on the shell (8) by the marking counterforms, around the removable element (20), during the overmolding step. A method of replacing a removable element (20) of an autonomous underwater drone (1) comprising a shell (8) overmolded around a body (2), the body (2) comprising a first removable element (20a) covered by a first layer of intermediate material (21a) positioned between the first removable element (20a) and an outer layer (42), characterized in that the method comprises a first step (A) in which the outer layer (42) is cut and removed, a second step (B) in which the first layer of intermediate material (21a) is removed, a third step (C) in which the first removable element (20a) is replaced by a second removable element (20b) and a fifth step (E) in which the second removable element (20b) is covered by an additional layer of polymer material (24). Replacement method according to claim 14, characterized in that it comprises a fourth step (D) in which the second removable element (20b) is covered by a second layer of intermediate material (21b) before the fifth step (E) of covering by the additional layer of polymer material (24), the second layer of intermediate material (21b) being positioned between the second removable element (20b) and the additional layer of polymer material (24).

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