WO2015005801A1

WO2015005801A1 - Autonomous device for cleaning a surface of a submerged structure

Info

Publication number: WO2015005801A1
Application number: PCT/NO2014/050128
Authority: WO
Inventors: Ole Molaug; Anders Molaug
Original assignee: Ole Molaug Eiendom As
Priority date: 2013-07-12
Filing date: 2014-07-10
Publication date: 2015-01-15
Also published as: NO20140872A1; NO336915B1

Abstract

An autonomous device (1) for cleaning a surface of a submerged structure (220), the device (1) including a chassis (7), and at least: one brush (2, 2'), two electrically driven driving wheels (3), one electrically driven propeller (4, 4') and at least one buoyancy body (6), at least one of the at least two driving wheels (3) being attached to one side of the chassis (7) and the other of the at least two driving wheels (3) being attached to the opposite side of the chassis (7), and a portion of the periphery of the driving wheel (3) projecting beyond the lower side edge (711, 731) of the chassis (7); and the brush (2, 2') projecting beyond the lower side edge (711, 731) of the chassis (7), and at least one of the at least one buoyancy body (6) projecting from one external side of the chassis (7), and the device (1) including a rechargeable internal energy source (53'). The invention also relates to a charging station (300) for the autonomous device (1) and a method of cleaning the submerged structure (220).

Description

AUTONOMOUS DEVICE FOR CLEANING A SURFACE OF A SUBMERGED STRUCTURE

The invention relates to a device for cleaning the surface of a submerged structure. More specifically, the invention relates to an autonomous device for cleaning the submerged structure. More specifically still, the invention relates to an autonomous device for cleaning a submerged seine in a net pen for farming fish.

For fish-farming, floating net pens may be used. A so-called open net pen includes, among other things, a floating body encircling a seine. The seine is closed at the bottom, and the seine forms an enclosure for the fish. The water flows freely through the seine. The fish is dependent on the water inside the seine being replaced by flow- through, for the oxygen content of the water to be satisfactory. Over time, the seine will become covered with fouling and the water flow-through decreases. The oxygen content inside the net pen decreases, which is unfortunate for the well-being, health and growth of the fish.

It is known in the trade to treat seines that are used for framing pens with impregnation compounds to prevent fouling. Such impregnation compounds are toxic in nature. Known impregnation compounds include impregnation compounds containing copper. It is also known that such seines must be sent to special washing facilities for cleaning and impregnation. This is an extensive job which includes, among other things, mobilizing a boat with a crane to lift the seine out of the sea and to put the seine back into the sea.

The patent document US2011/0185519 discloses a device for cleaning a submerged net, especially a net in a fish pen. The device is operated from a surface vessel. The device includes a rectangular or square chassis which is arranged to slide across the net, buoyancy bodies which are placed within the chassis, a driving means for moving the device along the net, a propeller for holding the device against and in contact with the net, and a cleaning member. The cleaning member may include a suction device which is integrated in the chassis, or a pressure washer. In addition, the device may be provided with brushes. The driving means may include hydraulically driven toothed wheels. The propeller may be hydraulically driven. The buoyancy body is arranged for the device, in a fully submerged position, to have a negative buoyancy of about 10 kg. The patent publication EP 2251102 discloses another device for cleaning a submerged net. The device is a device running on wheels and being secured from the surface. Energy is supplied from the surface through a cable, and pressurized liquid is supplied from the surface through a hose. Cleaning is carried out by pressure-washing the net.

The known devices have the drawback, among others, of having to be operated from the surface, from a vessel. Because of the work of mobilizing a vessel and crew, cleaning will not be performed until the fouling has become so extensive that the water flow-through the seine of the net pen has become reduced. There is therefore a need for a device and a method that can clean the seine regularly and before the fouling has become extensive.

The invention has for its object to remedy or reduce at least one of the drawbacks of the prior art or at least provide a useful alternative to the prior art.

The object is achieved through the features that are specified in the description below and in the claims that follow.

The invention is defined by the independent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect, the invention relates to an autonomous device for cleaning the surface of a submerged structure, the device including a chassis and at least: one brush, two electrically driven driving wheels, one electrically driven propeller and at least one buoyancy body, wherein at least one of the at least two driving wheels is attached to one side of the chassis and the other of the at least two driving wheels is attached to the opposite side of the chassis, and wherein a portion of the periphery of the driving wheel projects beyond the lower side edge of the chassis; and wherein the at least one electrically driven brush projects beyond the lower side edge of the chassis, and wherein at least one of the at least one buoyancy body projects from one external side of the chassis, and the device includes a rechargeable internal energy source.

The device may be arranged to be supplied with electrical energy by induction for the internal energy source to be charged from an electrical circuit including a secondary coil in a transformer, the secondary coil being housed in the buoyancy body. By an autonomous device is meant that the device is provided with an internal energy source so that the device can move without an external supply of energy. The internal energy source may be a battery, especially one or more rechargeable batteries. By an autonomous device is further meant that the device is provided with an internal control unit which controls at least the moving direction of the device without any external control signals from an operator or an external control unit, for example.

The buoyancy body may be provided with contact surfaces in an end portion. In the end portion, the buoyancy body may be provided with a dog facing one side of the device.

The brush may include an electrically driven rotatable brush.

The buoyancy body may extend along and on the outside of one side of the device. The buoyancy body may constitute a recovery member, for the device to be recovered, and an attachment, for the device to be hoisted out of a lake or sea. The buoyancy body may also form a guide that guides the device into a slit.

A perforated bottom plate may extend between the two opposite sides of the chassis so that the surface of the submerged structure is prevented from coming into contact with the at least one electrically driven propeller. The device may be arranged for cleaning a submerged structure. The submerged structure may comprise a seine in a net pen for farming fish. The submerged structure may be a hard surface. The submerged structure may be a hull of a ship.

In a second aspect, the invention relates to a charging station for an autonomous device for cleaning the surface of a submerged structure, the charging station including a winch positioned above a water surface, the winch being provided with a wire, the wire being provided with a recovery ring at one end portion, and the charging station further being provided with contactors to be able to supply the autonomous device with electrical energy when the autonomous device is in the recovery ring.

The charging station may further include a scissors mechanism which, at its first end portion, is attached at the winch, and which, at its second end portion, is attached to the recovery ring. The contactors may have a positioning enabling the supply of electrical energy to the autonomous device in the recovery ring when the recovery ring is in its upper position.

The plane of the recovery ring may be perpendicular to the plane of the scissors mechanism. The charging station may be provided with a support with a first end portion and a second end portion, and the support may be attached to the floating ring of a net pen at the second end portion. The support may be pivotably attached to the floating ring.

The winch may be provided with a motor for lifting and lowering the recovery ring by means of the wire. The charging station may include a housing which is attached to the first end portion of the support, and the housing may enclose the winch and the contactors.

In a third aspect, the invention relates to a method of cleaning the surface of a submerged structure, wherein the method includes moving a device, which is arranged to clean the surface, across the surface, and wherein the method further includes providing an autonomous device as described in the above. The method may further include providing a charging station as described in the above and charging the device in the charging station. The method may further include parking the device in the charging station. The method may further include lowering the device into a lake or sea and lifting the device out of the lake or sea by means of a winch with which the charging station is provided.

By cleaning a seine is meant that parts of fouling on the seine are removed. There may still be residues of fouling left after cleaning has been performed. One of the purposes of the invention is to keep the seine sufficiently clean so that the water flow- through the net pen is not reduced because of fouling . Residues of fouling will not prevent such water flow.

It is also a purpose of the invention that the seine can be cleaned so often that a significant layer of fouling will not form. The invention can be used in a net pen from the moment the seine is submerged into the sea. By regular treatment and with shorter time intervals than in the prior art, the fouling is kept down and no particularly heavy equipment or great force is required in order to remove the major part of the fouling that has formed since the previous cleaning. This has the advantage of making it unnecessary to treat the seine with impregnating compounds to prevent fouling.

An alternative charging station for an autonomous device for cleaning the surface of a submerged structure is described as well, wherein the alternative charging station may include an elongated chute with a first end portion and a second end portion, the first end portion forming an entrance portion; wherein the charging station may be provided with an electrical circuit between the first end portion and the second end portion and wherein the electrical circuit may be arranged to transmit electrical energy to the autonomous device; the chute may be provided with a slot, facing downwards in a position of application, in the longitudinal direction of the chute from the entrance portion to the second end portion; and the charging station may be provided with an attachment device arranged to position and orient the elongated chute substantially in a water surface.

The electrical circuit may include a second coil in a transformer and be arranged to transmit energy by induction to a first coil in the autonomous device.

The entrance portion may be funnel-shaped. The chute may be provided with a buoyancy means.

The attachment device may include an arm which, at one end portion, is attached to the chute and, at its opposite end portion, is provided with an attachment for attaching the charging station to a net pen. The attachment may be arranged for attachment to the railing of a net pen. The arm may be pivotably attached to the chute and pivot- ably attached to the attachment. The arm may be provided with an actuator for raising and lowering the arm. The arm may include two brace rods which, together with the attachment and a bracket projecting upwards at the second end portion of the chute, form a parallelogram.

In what follows, examples of preferred embodiments are described, which are visualized in the accompanying drawings, in which :

Figure 1 shows a perspective view of the device according to the invention;

Figure 2 shows a bottom view of the device, on another scale;

Figure 3 shows a top view of the device, on the same scale as figure 2;

Figure 4 shows a top view of the device on the same scale as figure 2, in which a top plate has been removed;

Figure 5 shows a side view of the device on the same scale as figure 2, viewed from the, in the position of application, top side of the device;

Figure 6 shows a side view of the device on the same scale as figure 2, in which a side plate has been removed;

Figure 7 shows, on a different scale, a charging station in a first embodiment for charging the device, the charging station being in a first, raised position; Figure 8 shows the same as figure 7, the charging station being in a second, lowered position;

Figure 9 shows a side view, on a different scale, of a charging station in a second embodiment for charging and storing the device, the charging station having trapped the device in a water surface;

Figure 10 shows a perspective view of the same as figure 9, the housing of the charging station being in a cutaway view;

Figure 11 shows the same as figure 10, the device having been lifted towards the housing of the charging station and the housing being shown complete;

Figure 12 shows the same as figure 10, the device having been lifted all the way up to the housing of the charging station; and

Figure 13 shows, schematically and on a larger scale, details of the connection of the charging station to the device and the energy transmission from the charging station to the device when the device is in a position like that shown in figure 12.

In the figures, the reference numeral 1 indicates a device for cleaning the surface of a submerged structure. The device 1 includes at least one brush 2, at least two driving wheels 3, at least one propeller 4, at least one battery case 5 and at least one buoyancy body 6. The device 1 also includes a chassis 7.

The device 1 is further provided with a bottom plate 8 which allows water flow- through. The device 1 may further be provided with an optional top plate 89, as shown in figure 3. The top plate 89 is shown as a perforated top plate 89 in order for it to allow water flow-through. In an alternative embodiment, the top plate 89 may be tight so that a water flow created by the at least one propeller 4 is guided out to the sides of the device 1.

The chassis 7 includes a first side plate 71 and a second side plate 73. The side plate 71 forms a first side edge 711, a second side edge 712, a third side edge 713 and a fourth side edge 714. Correspondingly, the second side plate 73 forms a first side edge 731, a second side edge 732, a third side edge 733 and a fourth side edge 734. Extending between the first side plate 71 and the second side plate 73, there are two chassis brace rods 75 and 77. The battery case 5 may form a portion of the chassis brace rod 75, 77. The chassis brace rod 75 is fixed to the side plates 71, 73 in portions at the side edges 712, 713 and 732, 733, respectively. The chassis brace rod 77 is fixed to the side plates 71, 73 in portions at the side edges 712, 714 and 732, 734, respectively.

The brush 2 extends between the first side plate 71 and the second side plate 73. In the figures, two brushes 2, 2' are shown. The brush 2 is releasably attached to the side plates 71 and 73 with two clips 21 in portions at the side edges 711, 714 and

731, 734, respectively. The brush 2' is releasably attached to the side plates 71 and 73 with two clips 21' in portions at the side edges 711, 713 and 731, 733, respectively. The periphery of the brush 2 projects beyond the side edge 711, 731 as shown in figures 1 and 5. The brushes 2, 2' are shown as cylinder-shaped brushes 2, 2' arranged to be rotatable, see also later in the description. In an alternative embodiment, the brushes 2, 2' are fixed brushes 2, 2' that are dragged across the surface of the submerged structure.

The driving wheels 3 project from the side plates 71, 73. The centres of the driving wheels 3 are closer to the side edges 711, 731 than to the opposite side edges 712,

732. The periphery of the driving wheel 3 projects beyond the side edge 711, 731, as is shown most clearly in figure 5.

The at least one propeller 4, 4' is positioned within the chassis 7 so that the rotational axis of the propeller 4, 4' is perpendicular to a plane defined by the side edges 712, 732. When operating, the propeller 4, 4' will push water through the chassis 7 in a direction from the side edges 711, 731 towards the side edges 712, 732. When the device 1 is provided with two propellers 4, 4', it is advantageous for the propellers 4, 4' to be arranged to be counter-rotating.

The buoyancy body 6 is attached to the outside of the side plate 71 with mounting brackets 61, 61' . The buoyancy body 6 extends on the outside of the side plate 71 from the side edge 713 to the side edge 714. The buoyancy body 6 may advantageously project beyond the side edges 713, 714 as shown in figures 2-4. In one embodiment, the buoyancy body 6 houses a secondary coil 51 which is electrically connected to an internal energy source 53' such as one or more rechargeable batteries 53 in the battery cases 5.

The bottom plate 8 extends between the side edges 711, 731 and between the brushes 2, 2'. The top plate 89 extends between the side edges 712, 732.

The propellers 4, 4' are driven by electric motors 41, 41', respectively, as shown in figure 4. Each of the wheels 3 is driven by a respective electric motor 31 via a gear transmission 33. The motors 31 also drive the brushes 2, 2' via gear transmissions 35, 35'. Each of the brushes 2, 2' are in two parts so that each of the motors 31 may drive its respective driving wheel 3 and brushes 2, 2' at different speeds. The gear transmission 35, 35' may be arranged for the brush 2 and the brush 2' to rotate in the same direction. In an alternative embodiment, the gear transmissions 35, 35' may be arranged for the brush 2 and the brush 2' to be counter-rotating . The gear transmissions 35, 35' may be arranged for the brush 2 and the brush 2' to rotate in the same direction as the wheels 3, or for them to rotate in the opposite direction to that of the wheels 3. In a further alternative embodiment, the brush 2, 2' may be a fixed brush.

The device 1 may have electrical energy supplied from a charging station 100, 300 to charge the rechargeable batteries 53.

The charging station 100 includes an elongated chute 110 as shown in figures 7 and 8. The chute 110 has a first end portion 111 and a second end portion 119. The first end portion 111 constitutes an entrance portion 112. The entrance portion 112 is formed with a funnel shape. Between the first end portion 111 and the second end portion 119 the charging station 100 is provided with an electrical circuit including a primary coil 151 in a transformer. The primary coil 151 may transmit electrical energy by induction to the secondary coil 51 of the device 1, positioned in the buoyancy body 6. The chute 110 is provided with a slot 113, facing downwards in the position of application, in the longitudinal direction of the chute 110. The slot 113 extends from the entrance portion 112 to the second end portion 119.

In an alternative embodiment, the device 1 may be charged by electrical energy being supplied through a mechanical contact as shown in figure 12, and as is described in what follows.

The charging station 100 is shown provided with a buoyancy means 120 at the second end portion 119 of the chute 110. In an alternative design, the buoyancy means 120 may be positioned elsewhere on the chute 110, for example in a portion between the entrance portion 112 and the second end portion 119. In an alternative embodiment, the charging station 100 may be provided with several buoyancy means 120.

The charging station 100 is provided with an attachment device 130. The attachment device 130 is arranged to position and orient the elongated chute 110 in a water surface 9. The attachment device 130 includes an arm 140 which, at its first end portion 141, is attached to the second end portion 119 of the chute 110. At its second end portion 149, the arm 140 is provided with an attachment 135 for attaching the charg- ing station 100 to a net pen 200. The attachment 135 is arranged to be attached to the railing 210 of a net pen 200, as shown in figures 7 and 8.

The arm 140 is pivotably attached to the second end portion 119 of the chute 110 and pivotably attached to the attachment 135. The arm 140 is provided with an actuator 143 for the arm 140 to be raised and lowered. The arm 140 is shown with two brace rods 145, 147 which, together with the attachment 135 and a bracket 148 projecting upwards at the second end portion 119 of the chute 110, form a parallelogram.

The arm 140 may be of designs different from the design of the arm 140 shown, for a charging station 100 to be raised and lowered. Cables necessary for supplying electrical energy to the charging station 100 are not shown as it is technically obvious to provide the charging station 100 with such. A control unit for the charging station 100 is not shown either.

The charging station 300 includes a support 340 which, at its first end portion 341, is fixed to a housing 390. At its second end portion 349, the support 340 is fixed to a floating ring 230 with an attachment 335, see figures 10-12.

The charging station 300 includes an electric motor 370 which is arranged to drive a winch 375 inside the housing 390. A wire 377 extends from the winch 375 to the recovery ring 310, see figure 10.

The charging station 300 includes a scissors mechanism 360 which, at its first end portion 361, is attached to the inside of the housing 390 at the winch 375. The scissors mechanism 360 is attached, at its second end portion 369, to a recovery ring 310. The plane of the recovery ring 310 is substantially perpendicular to the plane of the scissors mechanism 360 as shown in figures 9 and 10.

The charging station 300 may further be provided with a sensor (not shown) in the housing 390, registering whether the scissors mechanism 360 is subjected to a force directed in the plane of the scissors mechanism 360 and directed perpendicularly to the longitudinal direction of the scissors mechanism 360, when the scissors mechanism 360 is in its extended position as shown in figure 9. The housing 390 may be provided with one or more guides (not shown) for the scissors mechanism 360 and for the recovery ring 310.

In one embodiment, the device 1 may be provided with a buoyancy body 600. The buoyancy body 600 corresponds to the buoyancy body 6, and identical features and functions are not repeated. The same reference numerals indicate the same features. At one end portion 601, the buoyancy body 600 is provided with a dog 610 facing the first side plate 71 so that the dog 610 forms a recovery pocket 620 between the dog 610 and the mounting bracket 61. The recovery pocket 620 has a width that is larger than the diameter of the recovery ring 310, as shown in figure 13. The buoyancy body 600 may be provided, at one end portion 601, with a sensor (not shown) which is arranged to register whether the recovery ring 310 is positioned in the recovery pocket 620.

In its end portion 601, the buoyancy body 600 is further provided with external contact surfaces 630, 630' with an intermediate insulator 631. The contact surfaces 630, 630' may be in electrical contact with the rechargeable battery 53 of the device 1. Internally in the housing 390, the charging station 300 is provided with resilient contactors 395, 395', see figure 13, which come into contact with the contact surfaces 630, 630' when the device 1 is hoisted up to and partly into the housing 390 by means of the winch 375, the wire 377 and the recovery ring 310 as shown in figure 12. The recovery ring 310 is then in its upper position.

The autonomous device 1 is provided with an electronic, programmable control module (not shown). The control module is provided with various sensors such as an ac- celerometer, a GPS, a depth meter and a gyroscope, which enables the device 1 to register where it is positioned within a net pen 200, in what direction it is moving, if it is running into an obstacle and so on. The charging status of the battery 53 is registered as well. It is technically obvious how such a control module should be built for the device 1 to be autonomous. The control module may also cooperate with the control unit of the charging station 100 so that, for example, raising and lowering the arm 140 is controlled from the device 1.

The device 1 is programmed to move at certain times across a seine 220 of a net pen 200 in a pattern that covers all or parts of the internal surface of the seine 220. Such a pattern may include the device 1 moving by means of the driving wheels 3 substantially horizontally and clockwise along the internal submerged surface of the seine 220. The propeller 4, 4' keeps the device 1 in contact with the seine 220 in consequence of the water flow that is established. The brush 2, 2' can actively work the seine meshes 222 and loosen and remove fouling from the seine 220. The propeller 4, 4' creates a water flow that runs from the external side of the seine 220, through seine meshes 222, through the bottom plate 8 of the device 1 and out through the top plate 89 of the device 1. The water flow will bring fouling on the external side of the seine 220 to completely or partially project into the net pen 200. With that, the brush 2, 2' will completely or partially also remove fouling on the external side of the seine 220 even though the brush 2, 2' is working the seine meshes 222 from the internal side of the seine 220. The bottom plate 8 prevents the seine meshes 222 from coming into contact with the propeller 4, 4'. The device 1 is thereby prevented from tearing holes in the seine 220. In an alternative embodiment, the brush 2, 2' may be dragged across the internal side of the seine 220.

When the device 1 has completed a full circumference on the seine 220, the device 1 moves somewhat deeper down on the seine 220 by the driving wheels 3 rotating at different speeds. After that, the device 1 resumes its substantially horizontal direction of movement and completes yet another full circumference internally on the seine 220. This is repeated until the entire submerged surface of the seine 220 has been worked by the brush 2, 2' .

The battery capacity of the device 1 may be too small for the device 1 to clean the seine 220 on one charge. When the control unit of the device 1 registers that the battery 53 should be charged, the position of the device 1 in the seine 220 is recorded, that is to say the depth and horizontal distance relative to the charging station 100. The device 1 moves diagonally up the seine 220 until the buoyancy body 6 reaches the water surface 9. Then the device 1 moves in the desired direction in the surface 9 until the device 1 reaches the charging station 100 as is shown in figure 7 or the charging station 300 as is shown in figures 9 and 10.

The buoyancy body 6 projecting upwards is guided into the chute 110 of the charging station 100 by the funnel-shaped entrance portion 112. The device 1 stops at the second end portion 119 of the chute 110. The device 1 can register its position at the end portion 119 by the primary coil 151 of the charging station 100 coming close to the secondary coil 51 of the device 1. The buoyancy body 6 is inside the chute 110 and the mounting brackets 61, 61' project through the downward slot 113 of the chute 110. With that, the device 1 projects out of and downwards from the chute 110. When the device 1 is positioned in the chute 110 and has stopped against the end portion 119, the secondary coil 51 of the buoyancy body 6 and the primary coil 151 of the charging station 100 are positioned in such a way relative to each other that the battery 53 can be charged by inductive transmission of electrical energy from the charging station 100. During the transmission of electrical energy, the device 1 will be held in place in the chute 110 by the electromagnetic forces that arise between the primary coil 151 and the secondary coil 51. When the battery 53 has been charged, the device 1 may return to the position in which the cleaning operation was interrupted and con- tinue until the seine 220 has been cleaned. More charges as described may be required until the entire seine 220 has been cleaned.

The device 1 with the buoyancy body 600 projecting upwards is recovered by the recovery ring 310 as shown in figures 9 and 10. The opening of the recovery ring 310 is perpendicular to the floating ring 230 and the surface formed by the segments of the scissors mechanism 360, and the recovery ring 310 is partially submerged below the water surface 9. The recovery ring 310 is held in the sideways position by the scissors mechanism 360. The wire 377 holds both the recovery ring 310 and the scissors mechanism 360 in a vertical position. When the device 1 moves against the recovery ring 310, the scissors mechanism 360 will be moved along the floating ring 230. This movement of the scissors mechanism 360 is registered by a sensor in the housing 390. The sensor sends a signal via a control unit to the motor 370 which starts the winch 375. The winch 375 lifts up the recovery ring 310 by means of the wire 377. The device 1 hangs from the recovery ring 310 by the dog 610 on the buoyancy body 600. A sensor in the buoyancy body 600 registers that the recovery ring 310 is positioned in the recovery pocket 620. The sensor sends a signal to the control unit of the device 1 that the device 1 is ready to be hoisted out of the water and the control unit stops the motors 31, 41, 41' driving the wheels 3 and the propellers 4, 4'.

The device 1 is hoisted up to the bottom side of the housing 390 and so that at least the end portion 601 of the buoyancy body 600 is guided into the housing 390 as shown in figure 13. The end portion 601 is guided in a manner known per se into the housing 390 so that contactors 395, 395' in the housing 390 come into contact with a respective contact surface 630, 630' each. Electrical energy may then be transmitted from the charging station 300 to the rechargeable battery 53 of the device 1. The control unit of the device 1 is arranged to communicate with the control unit of the charging station 300. When the battery 53 has been sufficiently charged, the device 1 can communicate with the charging station 300 so that the device 1 is lowered into the sea with the wire 377 and the recovery ring 310. The wire 377 is then paid out so much that the recovery ring 310 comes out of the recovery pocket 320 when the device 1 has started the propellers 4, 4' and is floating in the sea. The sensor in the buoyancy body 600 registers the recovery ring 310 being out of the recovery pocket 320, and the control unit of the device 1 starts the driving wheels 3 so that the device 1 moves away from the recovery ring 310.

Internally in the seine 220, one or more objects may be suspended, forming one or more obstacles 250 along the wall of the seine 220. The device 1 will register it is hit- ting such an obstacle 250. In a first example, the device 1 will stop on such a collision, in order then to move in the opposite direction on the wall of the seine 220 until the device 1 hits the obstacle 250 again, from the opposite side. On the second collision, the device 1 turns again and simultaneously heads somewhat down on the wall of the seine 220. The whole wall of the seine 220 will thereby be cleaned. In a second example, on a collision with an obstacle 250, the device 1 will go back some distance on the wall of the seine 220 while the device 1 is simultaneously heading further down on the seine 220, and then resumes its original and substantially horizontal moving direction. If there is still a collision with the object 250, the actions are repeated until the device 1 has passed below the object 250. Then the device 1 heads up on the seine to the height it had before its collision with the object 250 and continues its substantially horizontal moving direction.

The dimensioning of the buoyancy body 6 is such that the device 1 has a slight negative buoyancy. The buoyancy body 6 will orient the device 1 in such a way that the buoyancy body 6 is at the top when the device 1 is in its position of application. Because of the water flow which is set up by the propeller 4, 4', the driving wheels 3 have contact with the seine 220 and will, together with the buoyancy body 6, keep the device 1 at the desired height on the seine 220. The driving wheels 3 may also have different speeds of rotation, which will bring the device 1 up or down the seine 220.

When the seine 220 has been cleaned, the device 1 returns to the charging station 100, 300 as described. The device 1 is parked in the charging station 100, 300 until the device 1 is to clean the seine 220 anew.

It may be advantageous for the charging station 100, 300 to be arranged in such a way that the device 1 can be lifted out of the sea, as is shown in figures 7, 11 and 12. This can be done when the device 1 is being charged, and when the device 1 is parked until the next cleaning operation. This has the advantage of the surface of the device 1 being allowed to dry, which prevents fouling of the device 1 itself. The housing 390 will also help to keep the device 1 dry.

The arm 140 may also be arranged to lift the device 1 so high that it comes above a jump net 240 and the railing 210. The attachment 135 may be arranged to be rotata- ble around a vertical axis so that the arm 140 can be pivoted to bring the device 1 out of the net pen 200 and above the floating ring 230 that encircles the net pen 200 on the outside of the net pen 200. This has the advantage of allowing personnel to stand on the floating ring 230 and carry out maintenance on the device 1, or take the device 1 out of the charging station 100 and bring the device 1 to another net pen. It may also be advantageous to lower the device 1 into the sea by means of the arm 140.

The support 340 is formed with a bent first end portion 341 as shown in figures 10-12. By rotation of the support 340 in the attachment 335, the device 1 will be moved over the railing 210 and positioned above the floating ring 230. The device can easily be lowered onto the floating ring 230 by paying out the wire 377 from the winch 375.

The device 1 is shown with one centred driving wheel 3 on either side. The invention is not limited to this embodiment. It may be advantageous to have several driving wheels on either side, for example two wheels or three wheels (not shown). This may be particularly advantageous when the seine 220 is hanging in folds transversal to the moving direction of the device 1. The device may then, at either end, be in contact with the seine 220 with the brushes 2, 2' whereas the centred driving wheels 3 do not reach down to the seine 220. The progress of the device 1 will thereby be brought to a halt. This can be remedied with driving wheels that are positioned closer to the side edges 713, 733; 714, 734. The device 1 may also be provided with a crawler drive on either side. A crawler drive may be gentler to the seine. A crawler drive may also be more practical if the device 1 is to be used for cleaning hard surfaces like a ship's hull, for example.

It should be noted that all the above-mentioned embodiments illustrate the invention, but do not restrict it, and persons skilled in the art may form many alternative embodiments without departing from the scope of the dependent claims. In the claims, reference numerals in brackets are not to be regarded as restrictive. The use of the verb "to comprise" and its various forms, does not exclude the presence of elements or steps that are not mentioned in the claims. The indefinite article "a" or "an" in front of an element does not exclude the presence of several elements like that. The fact that some features are stated in mutually different dependent claims does not indicate that a combination of these features cannot be used with advantage.

Claims

P a t e n t c l a i m s

1. An autonomous device (1) for cleaning a surface of a submerged structure (220), the device (1) comprising a chassis (7), and at least: one brush (2, 2'), two electrically driven driving wheels (3), one electrically driven propeller (4, 4') and at least one buoyancy body (6; 600), at least one of the at least two driving wheels (3) being attached to one side of the chassis (7) and the other of the at least two driving wheels (3) being attached to the opposite side of the chassis (7), and a portion of the periphery of the driving wheel (3) projecting beyond the lower side edge (711, 731) of the chassis (7); and the brush (2, 2') projecting beyond the lower side edge (711, 731) of the chassis (7), c h a r a c t e r i z e d i n that at least one of the at least one buoyancy body (6) projects from one external side of the chassis (7), and the device (1) includes a rechargeable internal energy source (53').

2. The autonomous device (1) according to claim 1, wherein the buoyancy body (600) is provided with contact surfaces (630, 630') at an end portion (601) .

3. The autonomous device (1) according to claim 2, wherein, at the end portion (601), the buoyancy body (600) is provided with a dog (610) facing one side (71) of the device (1).

4. The autonomous device (1) according to claim 1, wherein the brush (2, 2') comprises an electrically driven rotatable brush.

5. The autonomous device (1) according to claim 1, wherein the buoyancy body (6) extends along and on the outside of one side (71) of the device (1).

6. The autonomous device (1) according to claim 1, wherein a perforated bottom plate (8) extends between the two opposite sides of the chassis (7), so that the surface of the submerged structure (220) is prevented from coming into contact with the at least one electrically driven propeller (4, 4').

7. The autonomous device (1) according to claim 1, wherein the device ( 1) is arranged for cleaning a submerged structure comprising a seine (220) in a net pen for farming fish.

8. A charging station (300) for an autonomous device (1) for cleaning a surface of a submerged structure (220), c h a r a c t e r i z e d i n that the charging station (300) includes a winch (375) positioned above a water surface (9), the winch (375) is provided with a wire (377), the wire (377) being provided with a recovery ring (310) at one end portion, and the charging station (300) further being provided with contactors (395, 395') to be able to supply the autonomous device (1) with electrical energy when the autonomous device (1) is in the recovery ring (310).

9. The charging station (300) for an autonomous device (1) according to claim 8, wherein the charging station further includes a scissors mechanism (360) which is fixed (361), at its first end portion (361), at the winch (375) and which is attached, at its second end portion (369), to the recovery ring (310) .

10. The charging station (300) for an autonomous device (1) according to claim 8, wherein the contactors (395, 395') have been positioned for supplying the autonomous device (1) in the recovery ring (310) with electrical energy when the recovery ring (310) is in its upper position.

11. The charging station (300) for an autonomous device (1) according to claim 8, wherein the plane of the recovery ring (310) is perpendicular to the plane of the scissors mechanism (360).

12. The charging station (300) for an autonomous device (1) according to claim 8, wherein the charging station (300) is provided with a support (340) with a first end portion (341) and a second end portion (349), and wherein the support (340) is attached to the floating ring (230) of a net pen (200) at the second end portion.

13. The charging station (300) for an autonomous device (1) according to claim 12, wherein the support (340) is rotatably attached to the floating ring (230) .

14. The charging station (300) for an autonomous device (1) according to claim 8, wherein the winch (375) is provided with a motor (370) for lifting and lowering the recovery ring (310) with the wire (377).

15. The charging station (300) for an autonomous device (1) according to claims 8 and 12, wherein the charging station (300) includes a housing (390) at- tached to the first end portion (341) of the support (340) and wherein the housing (390) surrounds the winch (375) and the contactors (395, 395').

16. A method of cleaning a surface of a submerged structure (220), the method including moving a device (1) which is arranged to clean the surface across the surface, c h a r a c t e r i z e d i n that the method further includes providing an autonomous device (1) according to claim 1.

17. The method according to claim 16, wherein the method further includes providing a charging station (300) according to claim 8 and charging the device (1) in the charging station (300).

18. The method according to claim 17, wherein the method further includes parking the device (1) in the charging station (300) .

19. The method according to claim 17, wherein the method further includes lowering the device (1) into a lake or sea and lifting the device (1) out of the lake or sea by means of a winch (375) and a recovery ring (310) with which the charging station (300) is provided.