WO2010134022A1

WO2010134022A1 - Cleaner device for boat hulls

Info

Publication number: WO2010134022A1
Application number: PCT/IB2010/052206
Authority: WO
Inventors: Andrea Rizzo; Fabio Terzaghi
Original assignee: Andrea Rizzo; Fabio Terzaghi
Priority date: 2009-05-18
Filing date: 2010-05-18
Publication date: 2010-11-25
Also published as: IT1394625B1; ITTO20090381A1; EP2432682A1

Abstract

The present invention relates to a cleaner device (1,1A5IB) for boat hulls (15), said device (1,1A) having a positive or neutral hydrostatic trim when submerged and being of the type comprising at least one brush (7) for cleaning a boat hull (15), drive means (3), and means (4) for keeping said drive means (3) in contact with a boat hull (15), said device (1,1 A, IB) being self-moving and comprising a processing unit (8) adapted to process signals detected by sensors (91,92,93,101,102,103,50) and to select a motion trajectory (T,51) of the device as a function of said signals, said sensors (91,92,93,101,102,103,50) being adapted to detect at least one variation in the distance between said device (1,1 A, IB) and said boat hull (15).

Description

CLEANER DEVICE FOR BOAT HULLS

DESCRIPTION

The present invention relates to a cleaner device for boat hulls.

As is generally known, the bottom of boat hulls is subjected to formation of algae or cirripedes, such as the Chthamalus Stellatus (commonly called "dog's tooth"), which grow and proliferate on the bottom over time, thus leading to formation of encrustations which damage the hull and cause an increased fuel consumption in navigation (due to the resulting greater friction between the hull and the water).

For example, cirripedes like the "dog's tooth" grow by striking root into the hull, thereby creating grooves and holes which jeopardize the integrity thereof. In order to prevent such problems from arising, it is a common practice to clean the bottom of the boat hull periodically.

This cleaning can be carried out by pulling the boat aground, but this requires the use of suitable overhead travelling cranes and jib cranes, so that such a solution is adopted only when the hull bottom is to be subjected to periodic dry service; this work is also very difficult when it has to be carried out on big, heavy boats which cannot be lifted by means of the overhead travelling cranes and jib cranes normally available at touristic harbours, since it is necessary to prearrange a dock specifically for that purpose. Moreover, periodic dry-dock service may be planned at intervals of several years: therefore, cleaning the hull only in such occasions will result in an unacceptable growth of algae and cirripedes on the bottom, which is detrimental to both fuel consumption and hull integrity.

Aiming at overcoming this problem, it has been thought of reducing the cleaning intervals by carrying out in-water cleaning: in such a case, of course, the hull bottom is submerged and therefore the cleaning must be carried out underwater. Such a cleaning is normally done by a diver who, being equipped with a brush, dives underneath the boat and cleans the bottom thereof by removing the encrustations manually.

This task must however be accomplished in open waters to comply with regulations that make it problematical for a diver to work in harbours, and is therefore both difficult and costly. In the first place, in fact, the cleaning can only be done on days when the sea is calm, so that the diver can work safely; in addition, the boat must navigate to a suitable site outside of the harbour waters, stop there for the cleaning, and then go back to the harbour; furthermore, employing a skilled diver is rather expensive, since the cleaning may take a few hours.

Cleaner devices for boat hull bottoms are known in the art like the one described in American patent US 5,174,222 to Mark C. Rogers, which comprises inboard brushes, wheels, and a motor coupled to a propeller: the propeller is arranged centrally on the device body and is driven in a manner such as to generate a direct force that keeps the device adherent to the boat when in operation; during the cleaning process, the device stays adherent to the hull and is moved along the bottom in order to allow the brushes to remove the encrustations.

When such a device is operated by a diver, the hull cleaning operations suffers from those very same drawbacks already described. When said device is controlled remotely, i.e. by an operator who operates a control panel located out of the water, it is however still necessary to employ an operator for all the time required for cleaning the boat hull bottom.

Moreover, this kind of device may be used mainly on boats having hulls with no obstacles projecting outwards from the planking line; in fact, the operator controls the path followed by the device remotely by watching the images sent by the latter and taken by submarine video cameras: however, the resolution of the video cameras installed on the device, together with the fact that the water in the proximity of harbours is often turbid, does not allow the remote operator to see clearly any obstacles which might hinder the action of the device, with the risk that during the cleaning operation the device may come in contact with obstacles, thus getting damaged and/or moving away from the planking line, resulting in loss of adherence between the two and separation of the device from the hull.

Another device known in the art has been described in document GB 182,096 to LUDVIG THORSEN; in substance, this device is a brush provided with two motor rollers driven by pressurized water, which brush moves in one transversal direction along the boat keel; when the device has cleaned a keel strip, it is moved manually by an operator, so that it can clean another adjacent keel strip. This device however has some limits which compromise its utilization. First of all, the device cannot autonomously determine a trajectory (other than a straight line) on the keel, but simply runs forwards and backwards in a straight line, so that it requires the presence of an operator in order to be moved and carry out a complete cleaning action. Secondly, if there are any obstacles on the keel (e.g. the rudder, the propeller axles or steps), the above-described device will inevitably collide with such obstacles, with the risk of getting detached from the keel or even suffering damage.

These problems are felt even more in the case of boats having a so-called "gliding" hull, i.e. a hull which, when in motion, is mainly supported by the dynamic reaction of the water, resulting in the bow rising up and the stern staying submerged: in this kind of boats, in fact, the speeds attained are much higher than those reached by boats having a displacing hull, and the presence of encrustations will limit the maximum speed attainable, thus limiting the gliding effect and determining a significantly higher fuel consumption. Such boats are fitted on the bottom with longitudinal skids called "spray rails": the latter are shaped like steps projecting outwards from the planking line, and are used for promoting and delimiting the separation of the water flow underneath the boat by pushing it to the sides thereof, so as to improve the gliding effect and stabilize the boat in navigation. Due to the presence of spray rails, it is not advisable to use the device described in patent US 5,174,222 remotely, because an operator's error would cause the device to climb over a spray rail, resulting in the device moving away from the planking and reducing the suction force generated by the propeller that keeps it attached to the hull, thereby getting detached from the work surface. Not even the device described in patent GB 182,096 could be used with satisfactory results for several reasons.

As a matter of fact, this device, being only capable of moving in a straight line, could by no means avoid the spray rails and would inevitably run over them, thus moving away and getting detached from the hull. Furthermore, it should also be taken into account that, on these boats, the keel bottom to be cleaned is connected to the bulwarks, forming therewith a substantially acute angle (between approx. 60° and 90°) which, when the boat is in water, remains under the level of the water surface; of course, the keel bottom is submerged as well, and only the bulwarks emerge from the water.

This implies further problems, which de facto make it impossible to use such a device on gliding boats: in the first place, the operator should dive into the water in order to move the device, which would lead to all the aforementioned problems. In the second place, when during its straight forward motion the device arrives near the edge between the bottom and the bulwarks, it will inevitably become detached from the hull as it proceeds along its straight trajectory.

It follows that, for boats having a gliding hull, it will be necessary to keep using a diver, with all the drawbacks previously discussed. The object of the present invention is to provide a cleaner device for boats which can overcome the above-mentioned drawbacks.

A first idea on which the present invention is based is to provide a cleaner device for boat hulls having a non-negative, i.e. positive or neutral, hydrostatic trim when submerged and being of the type comprising at least one brush for cleaning a boat hull, drive means, and means for keeping said drive means in contact with a boat hull, wherein the device is self-moving and comprises a processing unit adapted to process signals detected by sensors and to select a motion trajectory of the device as a function of said signals, said sensors being adapted to detect at least one variation in the vertical distance of said device from said boat hull. By defining the trajectory in this way, it is advantageously possible for the device to lay securely onto the support plane defined by the external surface of the boat hull and to follow curved, linear or any other trajectories while at the same time avoiding to become detached from the hull due to the sudden end of the bottom near the bulwarks or the spray rails or any other obstacles which may be present. Further advantageous features will be set out in the appended claims, which are intended as an integral part of the present text.

These features as well as further advantages of the present invention will become apparent from the following description of an embodiment thereof as shown in the annexed drawings, which are supplied by way of non-limiting example, wherein: Fig. 1 is a side view of the self-moving device according to a first embodiment of the present invention;

Fig. 2 is a top view of the self-moving device of Fig. 1; Fig. 3 is a side view of the self-moving device of Fig. 1 in the operating condition with working sensors;

Fig. 4 is a sectional view of a boat hull with the device of Fig. 1 in the operating condition;

Fig. 5 shows a detail of an operating condition of the device of Fig. 4; Fig. 6 shows another detail of a different operating condition of the device of Fig. 4;

Fig. 7 is a side view of the boat hull of Fig. 4;

Fig. 8 is a side view of the boat hull of Fig. 4, on which an ultrasound transmitter is applied on the bow side, with the device of Fig. 1 in the operating condition;

Fig. 9 shows the hull bottom of the boat of Fig. 8 from below and a possible trajectory of the device of Fig. 1 ;

Fig. 10 shows a variant of the device of Fig. 1;

Fig. 11 shows from below a boat hull bottom fitted with a track that defines the path followed by the device of Fig. 10.

Referring now to Figs. 1 and 2, there is shown a self-moving device 1 according to a first embodiment of the present invention; it comprises a frame 2 on which drive means are mounted, e.g. four wheels 3, which are connected to and driven by a motor 6, e.g. an electric or pneumatic motor.

The wheels 3 may be capable of steering in order to allow the device to move along different trajectories on the hull; as an alternative, it is conceivable to prearrange a power train through which the motor 6 can drive one, two or more wheels, thus obtaining the desired steering effects by turning some wheels and stopping some other wheels.

The frame 2 defines internally a sealed compartment which houses the electric or pneumatic motor 6, the processing unit 8 and, more in general, all those components of the device which must not come in contact with water.

The motor 6 is supplied by the power line 12, which comes out of the frame of the device 1 on the side thereof opposite to that of the wheels 3, which power line is guided initially by a tubular section 11, so as to extend near the device in a direction substantially perpendicular to that of the plane containing the axes of the wheels 3, for the reasons which will be explained hereafter.

The self-moving device 1 also comprises means for keeping the drive means 3 in contact with a boat hull when submerged: such means may, for example, consist of a propeller 4 arranged in a duct 41 which opens onto the device side where the wheels 3 are arranged, and which is turned by a motor in order to generate a suction force between the device 1 and the support surface to keep the wheels adherent to the latter. It should be pointed out right away that, as an alternative, the drive means may consist of tracks (not shown) instead of the wheels 3, and that the propeller 4 may be replaced with different means for keeping the wheels or tracks in contact with the boat hull when the device 1 is submerged, such as, for example, nozzles spraying compressed air or similar means capable of generating on the device a force directed towards the side thereof fitted with wheels (or tracks). On the side fitted with wheels 3, or "device support side", there is also at least one brush 7, shown herein as a cylindrical rotary brush; more in general, it may have various shapes and it may be either fixed or rotary, combined with other brushes (also arranged on the support side of the self-moving device 1) and, finally, either motorized or idle: said brushes 7 are used for cleaning the boat hull when the self-moving device 1 is in operation. The self-moving device 1 further comprises a float chamber 5 which may be filled with air or water for the purpose of changing the hydrostatic trim of the device in the submerged condition in order to have it maintain a non-negative trim: the device 1 can therefore take either a positive trim, thus tending to float, or a neutral trim depending on the filling level of the float chamber 5. Maintaining a positive trim is advantageous when we consider that, when it is in operation, the device 1 stays under the hull and adheres thereto; therefore, the presence of a force pushing it upwards (floating) will improve its adherence to the hull. In order to fill the float chamber 5 with water it is sufficient to prearrange a conduit fitted with a suitable solenoid valve opening onto the outer surface of the device, and to open the valve when the latter is underwater; in order to empty the chamber 5 it will be necessary to connect the chamber to a compressed air tank, which may be housed directly in the frame 2 or be a remote one: in this latter case, the compressed air can be delivered to the chamber 5 through a pipe included in the power line 12. The self-moving device 1 also comprises sensor assemblies 9 and 10 arranged at the front and the rear: the sensors are so configured as to detect any obstacles present on the travel path of the self-moving device 1 before the latter runs into them: for example, in the solution shown herein they are placed at the front and rear ends of the device 1. In some less expensive solutions, the self-moving device 1 comprises only one sensor assembly 9 arranged frontally.

With reference also to Fig. 3, in the embodiment shown herein the sensors 9 and 10 comprise a total number of eight ultrasound sensors for submarine use 92, 93, 102, 103 like, without being limited to, those available from MAXBOTIX Inc. under the commercial name LV-MAXS ONAR-WRl . .

The sensor assemblies 9 and 10 optionally comprise also a contact sensor 91, 101, such as a contact or touch switch, e.g. like those available from ITT Industries under the commercial name "KSI Sealed Tact Switches" or the like, the use of which will be explained more in detail below. In accordance with the teachings of the present invention, the ultrasound sensors are mainly used for two distinct functions: a first function is to detect any obstacles projecting from the hull in the direction of forward motion of the device 1; in this case, the presence of an obstacle generates an echo of the ultrasonic signal produced by the sensor; the latter receives the echo thus generated and transmits the parameters thereof to the processing unit 8, which then determines the distance of the device (or, more correctly, of the sensor) from the obstacle.

In this case, the processing unit compares the distance from the obstacle thus acquired with a preset minimum threshold value. When the distance detected is equal to or smaller than the minimum threshold value, the processing unit 8 commands a rotation or trajectory change manoeuvre in order to avoid the obstacle.

A second function performed by said sensors is to allow to detect the presence of the hull under the device and to detect the boundary area of the hull itself beyond which the device will lose grip and will become detached from the hull, thus getting completely out of control.

In this case, at least one sensor detects (through the echo) the distance of the device 1 from the support surface (i.e. the hull).

Preferably, it detects the distance from a portion of said surface in front of the wheels of the device (in the direction of forward motion of the latter), so as to obtain a signal (based on which any trajectory changes are decided) which is indicative of the presence of the support plane and of any differences in height or discontinuities before the device itself, when travelling forward, reaches such differences in height or discontinuities. In this case, the operation of the control unit is somewhat opposite to the one described previously, in that when the distance detected increases or exceeds a preset maximum threshold, the processing unit 8 commands a rotation or trajectory change manoeuvre in order to prevent the device from becoming detached from the hull. The ultrasound sensors 92, 93, 102, 103 are in fact capable of detecting any obstacles within a variable distance range and are prearranged to operate in a submerged condition; as shown in Fig. 3, they are arranged in a manner such as to detect any obstacles or discontinuities or differences in height of the support surface in front of the moving device 1, like, for example, a sudden variation in the height of the support plane, as will be further explained with reference to the following figures. To this end, the ultrasound sensors 92, 93, 102, 103 are arranged in planes inclined by an angle between 25° and 45° relative to a plane passing through the axes of rotation of the wheels 3: thus, as shown in Fig. 3 by a dashed-dotted line, they can detect the presence of any obstacles or discontinuities or differences in height of the support surface before the robot reaches them: more specifically, the two pairs of sensors 93 and 103 face the device support side (the one fitted with wheels), whereas the pairs of sensors 92 and 102 face the opposite direction, i.e. that side of the device 1 which is not fitted with wheels.

It should also be noted that the sensor assembly 9 and 10 is arranged in a manner such that it projects outwards from the wheels 3, and the ultrasound sensors 92, 93, 102, 103 are located at the corners of the device: this allows to minimize the number of sensors while ensuring that they carry out the respective detections at the ends of the device. The processing unit 8 receives the data of the measurements taken by the ultrasound sensors 92, 93, 102, 103 and, if present, by the contact sensors 91 and 101. Said processing unit 8 also receives data relating to the running direction of the device 1 , e.g. data about the rotation of the wheels 3.

The processing unit 8 is also adapted to control the wheels 3, so as to move the device forwards or backwards or steer it.

By comparing the various readings of the ultrasound sensors 92, 93, 102, 103 and knowing the running direction of the device 1, the processing unit 8 can detect an obstacle or discontinuity or difference in height of the support surface before it comes in contact with the device 1 or the wheels 3 thereof, and can select a motion trajectory such that said obstacle or discontinuity or difference in height of the support surface is avoided. In a preferred embodiment of the invention, after having detected an obstacle or discontinuity or difference in height of the support surface, the processing unit 8 reverses the running direction and chooses a new motion trajectory of the device (i.e. the new running direction) at random: for example, it controls the wheels 3 in such a way that the device will turn by an angle between 20° and 40°, e.g. 30°.

Thus the trajectory followed by the device 1 on the hull in order to clean it is random and any trajectory changes are caused by the presence of obstacles or discontinuities or differences in height of the support surface, in the absence of which the device will proceed in a straight line. This implies that the cleaning of the hull is optimal only after the device has been submerged and operating for a certain time, e.g. two hours or longer; however, the fact that the device is self-moving and can choose autonomously its trajectories as a function of the obstacles it detects involves no drawbacks in this respect: in fact, it is sufficient to leave the device in operation for a certain period of time, during which it will need no guidance or control by an operator.

It must be pointed out that in this case the device does not trace a map of the hull, and its control unit 8 actually does not know the exact position of the device on the hull, but simply changes direction anytime it recognizes an obstacle or discontinuity or difference in height of the support surface which might compromise the forward motion in a straight line.

Therefore, in addition to the trajectory being random, also the instantaneous position of the device on the hull is unknown to the control unit.

This ensures an effective cost reduction and allows to avoid that construction complexity which would have to be incurred into if one were to know the exact position of the device on the hull bottom.

Optionally, although this is a more costly solution, the control unit may be so conceived as to trace a map of the hull and determine the precise position of the device thereon. This ensures a more effective cleaning action, even though the higher cost and the greater difficulty of implementation (of the sensors as well as of the navigation and mapping programs to be pre-loaded into the control unit) make it in principle preferable to employ a device adapted to move on the hull without generating a precise map thereof and without detecting its own coordinates on such a map. Reference will therefore be made below to such a simplified solution, even though in principle all of the following considerations will also be applicable to the case wherein the device is adapted to create or trace or receive a map of the hull and to determine its own exact position thereon.

It must also be stressed that, also in the case wherein the random trajectory of the device 1 leaves some regions of the hull dirty, it is nonetheless sufficient that most of the hull surface is clean, as can be attained by leaving the device in operation for a few hours; it will then suffice to repeat the treatment after a certain period of time; in this regard, reference should be made to the description of Fig. 8 for a variant which optimizes the cleaning of the most important areas of the hull. As far as the operation of the device 1 is concerned, reference should be made to Fig. 4: there is shown a sectional view of a hull 15 of a boat, in particular provided with a gliding hull, where it is possible to see the spray rails 16 arranged on the hull bottom and the edge between the hull bottom F and the bulwarks M. The self-moving device 1 is shown during an operating step for cleaning the bottom of the hull 15; it is kept adherent to the hull 15 by means of the propeller 4 and moves by means of the above-described wheels 3.

As it is moving, the brush 7 cleans the bottom from any algae and cirripedes which, being biodegradable, can then be released into the sea; this implies that the device 1 includes no container for collecting such residues, resulting in lower construction costs. The self-moving device 1 is connected through the power line 12 to a power supply 20, whether providing electric energy, compressed air or the like, arranged on the pier 21. As it is moving on the hull bottom, the device may encounter various obstacles or interruptions of the support surface, which are then avoided as described above. To this end, the processing unit 8 verifies that the measurements taken by the sensors 93, 103 facing the hull are always within a certain range of values comprised between the minimum threshold value and the maximum threshold value; when the measurement values do not fall within said range, the processing unit identifies the presence of an obstacle or discontinuity or difference in height of the support plane and provides for reversing the running direction by turning the vehicle by a random angle to the right or to the left.

A possible situation is shown in Fig. 5; in this case, the device 1 is running towards the spray rail 16: as the device 1 approaches the rail 1, one or both of the ultrasound sensors 93 (or 103) facing the device support plane detect a sudden variation in the distance of the support surface (which has gotten closer), in that the spray rail is an obstacle protruding from the ideal support plane.

In this case, the processing unit 8 reverses the running direction of the device and rotates it by an angle chosen randomly within the aforementioned range, after which the device continues to run until it encounters another obstacle and the process is repeated.

Another possible situation is shown in Fig. 6; in this case, the device is running towards the bulwark of the hull: as the device 1 approaches the bulwark, one or both of the ultrasound sensors 93 (or 103) facing the device support plane detect a sudden variation in the distance of the support surface (which has gotten farther); in this case, the processing unit 8 reverses the running direction of the device and rotates it by an angle chosen randomly within the aforementioned range, after which the device continues to run until it encounters another obstacle and the process is repeated. With reference to Fig. 7, the sensors 92 and 102 are arranged in a manner such as to detect the space in the direction opposite to that of the device support plane, and base their reason for existence on the fact that on the bottom of the hull 15 there may also be the axles 25 of the propellers 23 and/or the rudders 24 or, more in general, obstacles which the self-moving device 1 does not encounter on the support plane (the hull). In these cases it is necessary that the self-moving device 1 be provided with sensors 92, 102 arranged in a manner such as to detect any obstacles thus positioned; in fact, the device, when travelling autonomously, might get stuck between such obstacles and the hull or entangle the power cable 12 (e.g. around the propeller axle) when passing between such obstacles and the hull.

For this purpose, the processing unit 8 verifies that the measurements taken by the sensors 92, 102 facing the hull always exceed a threshold value; when the measurement values fall below the threshold value, the processing unit identifies the presence of an obstacle and reverses the running direction of the vehicle and rotates it by a random angle to the right or to the left.

The contact sensors 91 and 101 are optional and intervene as a safety measure in the event that any obstacles should not be detected by the ultrasound sensors 92, 93, 102, 103, e.g. if the spray rail 16 is encountered by the device in a region not covered by the sensors 93 and 103: in this case as well, the processing unit 8 will stop the device 1, reverse its running direction, and rotate it by a certain angle. This type of control accomplished by the processing unit also allows the device 1 to interpret the keel angle (keel edge) as a difference in height or unevenness of the support plane, so long as it is not so acute as to pose a risk of losing the condition of adherence of the device 1 to the hull 15, maintained by the propeller 4.

By appropriately setting the range and threshold values, it can be provided that the control unit only intervenes in certain situations, i.e. whenever there is a potential risk of detachment of the device 1 from the hull or it is necessary to prevent the device from getting between the latter and an obstacle; the device 1 can thus advantageously clean a hull autonomously, thereby solving the problems suffered by the known devices previously described. It is conceivable that the threshold and/or range values are preset at the factory or are set by the user depending on boat type and shape.

In this respect, it should be stressed that the device identifies as an "obstacle" any support surface variation outside the chosen range: in this sense, a spray rail or any other object on the hull surface may or may not be identified as an "obstacle", thus possibly determining the above-described path changes, depending on the measurements taken by the sensors; a spray rail, therefore, if encountered in a region where it protrudes only slightly from the hull profile, may even not be identified as a problem or an obstacle, in which case the device will continue to follow its trajectory as if there were no obstacles. It is also conceivable to delimit the area within which the device 1 is to operate, thereby optimizing the effects of the cleaning operation over time: as a matter of fact, it is advisable to concentrate the cleaning action onto the stern part of the hull bottom, especially for boats provided with a gliding hull; in such a case, in fact, in navigation the bow rises up above the water, so that any formation of algae or cirripedes in the bow area will not create any significant problems. According to the embodiment of Fig. 8, the device 1 may also be equipped with an additional sensor, such as, for example, an ultrasound receiver (not shown), combined with an ultrasound emitter 27 located underwater on the bow side (e.g. supported by a suitable support arm 28): when the device 1, as it is moving randomly on the hull bottom, approaches the emitter 27 at a predetermined distance, the ultrasound receiver installed in the self-moving device 1 detects the ultrasounds emitted by the emitter 27 and sends a signal to the processing unit 8, which will then select a trajectory as if the device had encountered an obstacle or a difference in the surface height, i.e. it will reverse the running direction and rotate the device by a certain angle. As far as the power supply 20 is concerned, it may be a column comprising all the electric or compressed air fittings required by the device 1, or more in particular it may be provided in the form of a carriage fitted with wheels and including a housing where the device 1 can be placed after use, thus obtaining a compact and easy-to-carry assembly; in this case it will be necessary to supply power to the carriage from the power outlets generally available on piers or by means of compressed air (e.g. supplied by a compressor and/or a suitable tank).

The carriage may also comprise a housing for the self-moving device, in which it can be placed before cleaning it, e.g. by using soft water. As an alternative to the power supply 20, the device 1 may be powered by a battery: in this case, the battery will be housed inside the device itself and there will be no external power line 12; in this regard, the chamber 5 will have to be sized appropriately to contain an air volume such that a non-negative trim in water will still be ensured despite the additional weight of the electric battery. It should also be stressed that the tubular profile 11 offers the advantage that it moves the free section of the power cable away from the device 1 , thus preventing it from getting entangled. hi this case, it is also appropriate to position a movable weight on the power cable 12, which weight may, for example, be shaped like an annular sleeve 30, and can slide freely over the cable 12 itself, as shown in Fig. 4, so that the cable 12 remains always taut between the device 1 and the power supply 20; of course, the annular weight and/or the chamber 5 will have to be sized adequately in order to prevent the weight 30 from detaching the device 1 from the hull.

In this regard, a further improvement can be attained by making the power cable non- floating for a length of approximately 2 metres starting from the device.

In yet another variant, the cable is rigid for a length of 2 metres and is arranged at a preferred angle relative to the device.

It is however worth pointing out that several types of sensors may be used as an alternative to those mentioned so far: for example, the ultrasound sensors may be replaced by optical distance sensors for in- water use, even though in principle optical sensors should be avoided or anyway should be selected with the utmost care, since harbour waters typically contain many impurities and might cause false signals. One possible trajectory T of the device 1 is shown in Fig. 9 by means of a dashed line: as can be seen, whenever the self-moving device encounters an obstacle or a difference in height of the support plane (whether it is a spray rail 16 or a bulwark of the boat), it reverses its running direction and turns by an angle which in this example is approximately 30°; it should be noted that in some situations the self-moving device may run over the spray rail: this is possible whenever the spray rail is not identified as an obstacle or a difference in height, e.g. because in the portion crossed by the robot it does not protrude much from the hull profile, thus remaining within the above- mentioned range. The device 1 is activated after having been placed underwater, with its wheels resting on the hull: in this case, in order to prevent the user from getting wet it is conceivable to utilize a positioning bar fitted on one end with a disengageable support intended for the device, so that, once the self-moving device has been positioned against the hull and its motor has been started, the bar can be disengaged, thus leaving the device free to operate. In a more complex version of the device 1, the control unit uses the sensors' signals to identify a projection on the hull which represents an obstacle and to discern an obstacle that can be run over by using appropriate safety measures from one that must be avoided. In this respect, the control unit will make such a distinction by comparing the values measured by the sensors with preset threshold values.

For example, assuming that the distance threshold from which a projection is considered to be an obstacle has been set to 20 cm, and assuming that the threshold that defines an obstacle to be avoided has been set to 30 cm: if the sensors' readings indicate a projection between 20 and 30 cm, then the control unit will identify the presence of an obstacle that can be run over and controls the device in a manner such that its trajectory is not changed, while however adopting some safety measures, e.g. a higher revolution speed of the propeller 4 in order to increase the force that keeps the device in adherence to the hull, and possibly a slower forward speed. According to another variant, it is conceivable to provide the self-moving device with sensors adapted to follow a track arranged on the hull.

This variant is shown in Figs. 10 and 11: as can be seen, the device IA lacks the sensor assemblies 9 and 10, but includes a sensor 50 which may be, for example, a sensor adapted to detect the presence of a magnetic field; for simplicity, the parts of the device IA being equivalent to and having the same functions as those of the device 1 are designated by the same reference numerals and will not be described any further.

In combination with the sensor 50, the bottom of the hull 15 includes a track 51, e.g. a magnetic track, an electric cable through which current may flow or the like, the magnetic field of which can be detected by the sensor 50.

Said track 51 may advantageously be provided by burying it into the hull material, or by associating it with the hull surface, e.g. by means of adhesives, rivets or the like, and extends on the hull bottom to create a cleaning path which can be followed by the device IA without encountering any obstacles. hi this respect, it can be noticed how the track 51 shown in Fig. 11 extends around the spray rails 16 and crosses the central area of the keel in a point near the middle of the hull length, where presumably the keel angle is not so sharp as to cause the device to lose grip.

When the device IA is placed on the track 51, it detects the presence of the latter and the processing unit activates the drive system, e.g. the wheels, so as to move the device

IA along the track to follow the cleaning path defined by the track itself.

It must be pointed out that, advantageously, the track 51 may also be applied to existing boats, or may be applied during the boat building process.

Thus, advantageously, the hull cleaning action can be concentrated on the most important areas, e.g. on the stern side.

It should be noted that the track 51 is continuous and defines a closed loop, so that it can be followed continuously by the device.

The presence of a broken or discontinuous track would actually imply the risk that the device might lose it, thus proceeding randomly until the track is detected again; it must be remembered that this device cannot determine its own position on the hull or the keel, but simply follows the track without creating a map of the cleaned or covered areas and of the areas still to be cleaned.

Alternative examples of a sensor 50 and a track 51 may consist of optical sensors, e.g. infrared sensors adapted to detect a track drawn on a hull by means of a reflecting paint or a paint of a colour contrasting with that of the hull, even though in principle these types of sensors may suffer the same problems as the optical sensors previously discussed.

In this case, furthermore, the vegetation accumulated on the hull may pose some additional problems; in fact, the self-moving device may not be able to detect the track correctly.

A further variant that solves this problem provides for combining both the sensor assemblies 9 and 10 and the sensor 50 on the same device, and for prearranging the track 51 on the hull as previously described.

In this condition it is possible to obtain a self-moving device of the type IB shown in Fig. 12, where the parts equivalent to and having the same functions as those of the previous figures are designated by the same reference numerals and will not be described any further. The device IB operates as follows: after having been placed near the track, it can follow it on the hull (as described for the device IA); should the device IB lose the references of the track 51 for any reason (e.g. a strong water current or dirt accumulated on the track), it would continue to perform its cleaning work by following a random trajectory and by referring solely to the signals sent by the sensor assemblies 9 and 10, as described for the device 1.

During its random motion on the hull, the device IB will sooner or later encounter the track 51 again and will follow it again on the hull.

In this manner it is possible to obtain a self-moving device IB which optimizes the cleaning path and which, in the event of a malfunction or loss of the track reference, can continue to operate automatically until the track is detected again.

One type of track which may be suitable for this purpose is a magnetic track made of iron or another material that can be detected by a magnetic sensor, used in combination with a magnetic sensor fitted to the device. A further advantageous feature which may be fitted to this device, and which may be combined with the different embodiments described so far, is a gyroscope of a per se known type, which will not be described any further herein.

The presence of a gyroscope in communication with the control unit 8, in fact, allows the latter to detect the angle of rotation as the device is running. As aforementioned, the rotations carried out in the presence of obstacles or differences in height or discontinuities may occur at random, but in any case it may be appropriate that the control unit 8 knows the degrees of rotation of the device. In fact, this may sometimes be necessary because in conditions of poor grip the angle of rotation is not directly and univocally related to the time of rotation commanded by the control unit 8 to the wheels or tracks: the latter may in fact lose grip (it should be remembered that the working environment is submarine, and when the hull is covered with cirripedes and encrustations the adherence may be very poor), and the device may remain still or turn by very few degrees. One type of gyroscope suitable for this purpose is the single-axis type, even though in principle it is also possible to use two-axis or three-axis gyroscopes, e.g. for more advanced applications.

These gyroscopes can also provide the control unit 8 with information about the angles of inclination of the device relative to the hull or to the horizontal. Such information is useful when the geometric characteristics of the hull on which the device is to operate are known beforehand and when such information has been entered and stored in the control unit 8.

In this case, in fact, the control unit 8 can, based on its own inclination (detected through the gyroscope) find its own position relative to the hull. The control unit compares the angle of inclination detected by the gyroscope with a set of predefined values indicating the angle of the hull, and based on this comparison it can detect the position of the device on the hull, so that it can issue a rotation command if the device is in a region near the bow (where its action is not very useful) or if it is getting too close to either bulwark. The present invention also relates to a method for controlling a cleaner device for boat hulls 15, preferably for gliding hulls, comprising the steps of: a- imparting a forward motion in a straight line to the device b- detecting, during said forward motion in a straight line, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface by means of sensors, preferably ultrasound sensors c- if any obstacles and/or discontinuities or differences in height are detected, stopping the device and imparting thereto a rotation by a certain angle d- at the end of said rotation, detecting any obstacles and/or discontinuities or differences in height of said hull or of the device support surface by means of sensors, preferably ultrasound sensors e- repeating the method from step a in the absence of any obstacles and/or discontinuities or differences in height or in the event of a negative detection of said obstacles and/or discontinuities or differences in height. A variant of the above-described method comprises the following steps: i- detecting a track ii- imparting a forward and/or rotational motion to the device in order to follow said track iii- if said track is lost during said motion, imparting a forward motion in a straight line to the device iv- detecting, during said forward motion in a straight line, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface and contemporarily detecting the presence of a track by means of sensors, preferably ultrasound sensors v- if any obstacles and/or discontinuities or differences in height are detected, stopping the device and imparting thereto a rotation by a certain angle, and, at the end of said rotation, detecting by means of sensors, preferably ultrasound sensors, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface, and repeating the method from step iii in the absence of any obstacles and/or discontinuities or differences in height or in the event of a negative detection of said obstacles and/or discontinuities or differences in height vi- if a track is detected, repeating the method from step i .

Of course, these two methods may be complemented by the variants described above, in particular as regards the detection of the area to be cleaned by means of the ultrasound emitter 27 or the gyroscope.

* * * * *

Claims

_CLAIMS

1. Cleaner device (1,1A₅IB) for boat hulls (15), said device (1,1A) having a positive or neutral hydrostatic trim when submerged and being of the type comprising at least one brush (7) for cleaning a boat hull (15), drive means (3), and means (4) for keeping said drive means (3) in contact with a boat hull (15), characterized in that said device (1,1 A, IB) is self-moving and comprises a processing unit (8) adapted to process signals detected by sensors (91,92,93,101,102,103,50) and to select a motion trajectory (T,51) of the device as a function of said signals, said sensors (91,92,93,101,102,103,50) being adapted to detect at least one variation in the distance between said device ( 1 , 1 A, 1 B) and said boat hull (15).

2. Device (1) according to claim 1, wherein the sensors (91,92,93,101,102,103) are adapted to detect remotely at least one obstacle on the hull, so as to avoid any obstacles before the device (1,1 A) gets in contact therewith.

3. Device (1) according to claim 1 or 2, wherein said sensors are ultrasound sensors arranged in a manner such as to detect any discontinuities or differences in height of a support surface of said device.

4. Device (1) according to claim 2 or 3, wherein the sensors (93,103) are ultrasound sensors arranged on the device (1) in a manner such as to project outwards with respect to the drive means (3), so that, when the device (1) is adherent to a hull, they carry out detections at the ends of the device (1) in the direction of the hull.

5. Device (1) according to any of claims 1 to 4, wherein the sensors (92,102) are ultrasound sensors arranged on the device (1) in a manner such as to project outwards with respect to the drive means (3), so that, when the device (1) is adherent to a hull, they carry out detections at the ends of the device (1) in the direction opposite to that of the hull.

6. Device (1) according to one or more of claims 1 to 5, wherein the sensors (92, 93, 102, 103) are arranged in planes inclined by an angle between 25° and 45° relative to the common plane passing through the drive means (3).

7. Device (1) according to one or more of claims 1 to 6, wherein, when an obstacle and/or a discontinuity or a difference in height of the support plane are detected and the device (1) is moving in a straight line, the processing unit (8) reverses the running direction of the device and controls a rotation of the latter by an angle chosen randomly within the range of 20° to 40°, preferably of 30°.

8. Device (1) according to one or more of claims 1 to 7, further comprising an ultrasound receiver adapted to receive a signal emitted by an ultrasound emitter (27) and consequently to send a signal to the processing unit (8) for selecting a new motion trajectory of the device (1).

9. Device (IA) according to claim 8, wherein at least one signal emitted by an ultrasound sensor is directed towards a support plane of said device.

10. Device (IA) according to claim 1, wherein the sensors (50) are adapted to detect at least one track (51) provided on a hull (15), and wherein the processing unit (8) is adapted to select a trajectory of the vehicle (IA) along said track.

11. Device (IA) according to claim 10, wherein the sensors (50) are adapted to detect at least one magnetic field, said track (51) being a magnetic track, an electric cable through which current may flow, or the like.

12. Combination of a boat and a device (IA) according to any of claims 10 and 11, wherein said boat comprises a hull (15) with which a track (51) is associated which can be detected by a sensor (50), and wherein the device (IA) comprises at least one sensor (50) adapted to detect said track (51).

13. Device (IB) according to one or more of claims 1 to 9, further comprising sensors (50) adapted to detect at least one track (51) provided on a hull (15), and wherein, if the reference of said track is lost, the processing unit (8) is adapted to select a random trajectory of the vehicle (IA) until the track (51) is detected again.

14. Method for controlling a cleaner device for boat hulls (15), preferably for gliding hulls, comprising the steps of: a- imparting a forward motion in a straight line to the device b- detecting, during said forward motion in a straight line, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface by means of sensors, preferably ultrasound sensors c- if any obstacles and/or discontinuities or differences in height are detected, stopping the device and imparting thereto a rotation by a certain angle d- at the end of said rotation, detecting any obstacles and/or discontinuities or differences in height of said hull or of the device support surface by means of sensors, preferably ultrasound sensors e- repeating the method from step a in the absence of any obstacles and/or discontinuities or differences in height or in the event of a negative detection of said obstacles and/or discontinuities or differences in height.

15. Method for controlling a cleaner device for boat hulls (15), preferably for gliding hulls, comprising the steps of: i- detecting a track ii- imparting a forward and/or rotational motion to the device in order to follow said track iii- if said track is lost during said motion, imparting a forward motion in a straight line to the device iv- detecting, during said forward motion in a straight line, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface and contemporarily detecting the presence of a track by means of sensors, preferably ultrasound sensors v- if any obstacles and/or discontinuities or differences in height are detected, stopping the device and imparting thereto a rotation by a certain angle, and, at the end of said rotation, detecting by means of sensors, preferably ultrasound sensors, any obstacles and/or discontinuities or differences in height of said hull or of the device support surface, and repeating the method from step iii in the absence of any obstacles and/or discontinuities or differences in height or in the event of a negative detection of said obstacles and/or discontinuities or differences in height vi- if a track is detected, repeating the method from step i .