Technical Field

[0001] The present disclosure relates to a method, system and an unmanned aerial vehicle for repelling a marine animal, such as sharks, from an undesired target. In particular, the method and system utilises one or more unmanned aerial vehicles to intercept and repel sharks from humans, such as swimmers and surfers, in a body of water.

Background

[0002] Despite its rare occurrence, shark attacks have long been a problem for many beach visitors such as swimmers, surfers or divers. Shark attacks can have lasting detrimental effects on the local tourism industry due to residents and tourists being deterred from visiting the beach.

[0003] Various methods have been used to deter sharks from entering or remaining in a beach area used by humans. Commonly used methods include the placement of shark nets and/or drumlines in or around the beach area. Drumlines typically use baited hooks that lure and capture sharks. Shark nets are submerged in the water surrounding a beach area to prevent sharks from entering the beach area and capture sharks by entanglement. However, a major problem with such methods, in particular the use of shark nets, is that they not only result in the capture and harm of sharks, but also often other marine animals including threatened and endangered species such as dolphins, turtles, whales and dugongs. This can cause significant harm to the marine ecosystem.

[0004] To avoid harming sharks and other marine animals, various electric shark repellent devices have been proposed. These electric shark repellent devices work on the premise of targeting the highly-sensitive electric receptor of sharks, known as the ampullae of Lorenzini located in the shark’s nose and head, which allows the shark to sense electrical signals from the movement of their prey at close distances. Such electric shark repellent devices typically utilise an electric field generator to transmit an electric field in the water that exceeds the sensory load of the shark’s ampullae of Lorenzini, thus causing the shark to be irritated and turn away upon encountering the electric field. In contrast, humans and other marine animals unrelated to sharks lack this sensitivity to electric fields, and are therefore avoided from harm caused by such electric fields.

[0005] Some electric shark repellent devices are typically used as personal devices only and may be worn by individual humans, in the form of an antenna tethered to the ankle, or attached to equipment such as surfboards, for example. Accordingly, such devices act as passive means of deterring sharks that protect the individual wearer only and not the general public. Such personal electric shark repellent devices can also be uncomfortable for the user to wear. Further, such electric shark repellent devices do not provide any means for identifying sharks in the beach area.

Object

[0006] It is an object of the present disclosure to substantially overcome or ameliorate one or more of the above disadvantages, or at least provide a useful alternative.

Summary

[0007] In accordance with an aspect of the present disclosure, there is provided a method of operating one or more unmanned aerial vehicles (UAV s) to repel a marine animal from an undesired target, the method comprising: capturing, by an image capture system of one of the UAVs, aerial image data of a body of water; identifying the marine animal in the body of water based on the aerial image data; determining a predicted path of the marine animal based on the aerial image data; determining whether the marine animal is moving towards the undesired target based on the predicted path of the marine animal; and in response to the determination that the marine animal is moving towards the undesired target, emitting, by a signal device of one of the UAVs, an underwater signal in the predicted path to repel the marine animal from the undesired target.

[0008] The step of determining the predicted path of the marine animal may comprise: receiving, by a Global Positioning System (GPS) receiver of one of the UAVs, geolocation data; calculating positional information of the marine animal in two-dimensional space based on the aerial image data and the geolocation data; and calculating a velocity of the marine animal based on the positional information of the marine animal.

[0009] The step of determining the predicted path of the marine animal may comprise: receiving, by a Global Positioning System (GPS) receiver of one of the UAVs, geolocation data; measuring, by a sonar device of one of the UAVs, sonar data of the body of water; calculating positional information of the marine animal in three-dimensional space based on the aerial image data, the geolocation data and the sonar data; and calculating a velocity of the marine animal based on the positional information of the marine animal.

[0010] The step of determining whether the marine animal is moving towards the undesired target may comprise: identifying the undesired target based on the aerial image data; calculating positional information of the undesired target in two-dimensional space based on the aerial image data and the geolocation data; and comparing the predicted path of the marine animal with the positional information of the undesired target.

[0011] The underwater signal may be emitted in the predicted path between the marine animal and the undesired target.

[0012] The underwater signal may be one or more of an electric field, a light and an acoustic signal.

[0013] In accordance with another aspect of the present disclosure, there is provided an unmanned aerial vehicle (UAV) for repelling a marine animal from an undesired target, the UAV comprising: a fuselage; a communication system configured for wireless communications; a signal device configured to emit an underwater signal; a deployment mechanism mounted to the fuselage, the deployment mechanism configurable between an undeployed configuration in which the signal device is stored within or near the fuselage and a deployed configuration in which the signal device is spaced from the fuselage; and a controlling system configured to: receive, via the communication system, positional information of the marine animal; navigate the UAV over the body of water between the marine animal and the undesired target based on the positional information of the marine animal; operate the deployment mechanism from the undeployed configuration to the deployed configuration; operate the signal device to generate an underwater signal in the body of water; determine a predicted path of the marine animal based on the positional information of the marine animal; determine whether the marine animal is moving towards the undesired target based on the predicted path of the marine animal; and in response to the determination that the marine animal is moving towards the undesired target, navigate the UAV such that the emitted underwater signal is in the predicted path to repel the marine animal from the undesired target.

[0014] The controlling system may be configured to determine the predicted path of the marine animal by calculating a velocity of the marine animal in the body of water in two- dimensional space based on the positional information of the marine animal.

[0015] The UAV may further comprise a sonar device configured to measure underwater sonar data. The sonar device may be stored within or near the fuselage in the undeployed configuration of the deployment mechanism and the sonar device may be spaced from the fuselage in the deployed configuration of the deployment mechanism. The controlling system may be configured to determine the predicted path of the marine animal by: operating the sonar device to measure underwater sonar data in the body of water; and calculating a velocity of the marine animal in the body of water in three-dimensional space based on the positional information of the marine animal and the underwater sonar data.

[0016] The controlling system may be further configured to receive, via the communication system, positional information of the undesired target. The controlling system may be configured to determine whether the marine animal is moving towards the undesired target by comparing the predicted path of the marine animal with the positional information of the undesired target.

[0017] The underwater signal may be emitted in the predicted path between the marine animal and the undesired target.

[0018] The underwater signal may be one or more of an electric field, a light and an acoustic signal.

[0019] In accordance with yet another aspect of the present disclosure, there is provided a system for repelling a marine animal from an undesired target, the system comprising: one or more first unmanned aerial vehicles (UAVs), each first UAV according to the above described embodiments; and one or more second UAVs, each second UAV comprising: a fuselage; an image capture system configured to capture aerial image data; a communication system configured for wireless communications; a Global Positioning System (GPS) receiver; and a controlling system configured to: navigate the second UAV over a body of water; operate the image capture system to capture aerial image data of the body of water; identify the marine animal in the body of water based on the aerial image data; and receive, via the GPS receiver, geolocation data; calculate positional information of the marine animal based on the aerial image data and the geolocation data; and transmit, via the communication system, the positional information of the marine animal to one of the one or more first UAVs.

[0020] In accordance with yet another aspect of the present disclosure, there is provided an unmanned aerial vehicle (UAV) for repelling a marine animal from an undesired target, the UAV comprising: a fuselage; an image capture system configured to capture aerial image data; a signal device configured to emit an underwater signal; a deployment mechanism mounted to the fuselage, the deployment mechanism configurable between an undeployed configuration in which the signal device is stored within or near the fuselage and a deployed configuration in which the signal device is spaced from the fuselage; and a controlling system configured to: navigate the UAV over a body of water; operate the image capture system to capture aerial image data of the body of water; identify the marine animal in the body of water based on the aerial image data; receive, via the GPS receiver, geolocation data; calculate positional information of the marine animal based on the aerial image data and the geolocation data; navigate the UAV over the body of water between the marine animal and the undesired target based on the positional information of the marine animal; operate the deployment mechanism from the undeployed configuration to the deployed configuration; operate the signal device to emit an underwater signal in the body of water; determine a predicted path of the marine animal based on the positional information of the marine animal; determine whether the marine animal is moving towards the undesired target based on the predicted path of the marine animal; and in response to the determination that the marine animal is moving towards the undesired target, navigate the UAV such that the emitted underwater signal is in the predicted path to repel the marine animal from the undesired target. [0021] The controlling system may be configured to determine the predicted path of the marine animal by calculating a velocity of the marine animal in the body of water in two- dimensional space based on the positional information of the marine animal.

[0022] The UAV may further comprise a sonar device configured to measure underwater sonar data. The sonar device may be stored within or near the fuselage in the undeployed configuration of the deployment mechanism and the sonar device may be spaced from the fuselage in the deployed configuration of the deployment mechanism. The controlling system may be configured to determine the predicted path of the marine animal by: operating the sonar device to measure underwater sonar data in the body of water; and calculating a velocity of the marine animal in the body of water in three-dimensional space based on the positional information of the marine animal and the underwater sonar data.

[0023] The controlling system may be further configured to: identify the undesired target in the body of water based on the aerial image data; and calculate positional information of the undesired target based on the aerial image data and the geolocation data, and wherein the controlling system may be configured to determine whether the marine animal is moving towards the undesired target by: comparing the predicted path of the marine animal with the positional information of the undesired target.

[0024] The underwater signal may be emitted in the predicted path between the marine animal and the undesired target.

[0025] The underwater signal may be one or more of an electric field, a light and an acoustic signal.

[0026] In accordance with an embodiment of the present disclosure, there is provided an unmanned aerial vehicle (UAV), comprising: a fuselage; a sonar device configured to measure underwater sonar data; an electric field generator configured to generate an underwater electric field for repelling a marine animal; and a deployment mechanism mounted to the fuselage, wherein the deployment mechanism is configured to move the sonar device and the electric field generator from an undeployed position in which the sonar device and the electric field generator are stored within or near the fuselage to a deployed position in which the sonar device and the electric field generator are spaced from the fuselage such that the UAV is able to be located in the air over a body of water while the sonar device and the electric field generator are immersed in the body of water.

[0027] The deployment mechanism may comprise an inflatable member and an inflator activable to inflate the inflatable member. The inflatable member may have a first end attached to the fuselage and a second free end. The sonar device may be attached to the inflatable member at the second free end. The electric field generator may be attached to the inflatable member between the first end and the second free end.

[0028] In the undeployed position, the inflatable member may be deflated and the second free end may be at or adjacent the fuselage. In the deployed position, the inflatable member may be fully inflated by the inflator and substantially rigid such that the second free end is spaced from the fuselage and the sonar device and the electronic field generator are substantially fixed relative to the fuselage.

[0029] The inflator may be in the form of a replaceable carbon dioxide cartridge.

[0030] The UAV may further comprise a controlling system configured to at least activate the inflator to move the sonar device and the electric field generator from the undeployed position to the deployed position.

Brief Description of Drawings

[0031] Embodiments of the present disclosure will now be described hereinafter, by way of examples only, with reference to the accompanying drawings, in which: [0032] Fig. 1 is a perspective view of an embodiment of a system for repelling a marine animal from an undesired target;

[0033] Fig. 2 is a schematic illustration of the system of Fig. 1;

[0034] Fig. 3 is a side view of an embodiment of an operator unmanned aerial vehicle over a body of water, with a deployment mechanism in a deployed position;

[0035] Fig. 4 is a flow diagram showing an embodiment of a method for repelling a marine animal from an undesired target;

[0036] Fig. 5(a) is a top view of the operator unmanned aerial vehicle of Fig. 3 in an initial deployment position between a marine animal and an undesired target;

[0037] Fig. 5(b) is a top view of the operator unmanned aerial vehicle of Fig. 3 in an initial deployment position between a marine animal and an undesired target, where the marine animal is deemed to be in close proximity to the undesired target;

[0038] Fig. 6 is a top view of the operator unmanned aerial vehicle of Fig. 3 at the time of interception with a marine animal;

[0039] Fig. 7 is another top view of the operator unmanned aerial vehicle of Fig. 3 at the time of interception with a marine animal, and with an undesired target;

[0040] Figs. 8(a) to 8(d) are side views of the operator unmanned aerial vehicle of Fig. 3, at the time of interception with a marine animal, and with the marine animal being at varying depths; and

[0041] Fig. 9 is a flow diagram showing another embodiment of a method for repelling a marine animal from an undesired target.

Description of Embodiments

[0042] Figs. 1 and 2 show an embodiment of a system 10 for repelling a marine animal 20 from an undesired target 30. In this embodiment, the marine animal 20 is a shark 20 and the undesired target 30 is a human 30, such as swimmer or a surfer, for example. The system 10 comprises an ‘observer’ unmanned aerial vehicle (UAV) 100 that is configured to survey a predefined body of water 40 adjacent a beach and to identify the shark 20 and the human 30 in the body of water 40, and an ‘operator’ UAV 200 in wireless communication with the observer UAV 100 and which is configured to intercept and repel the shark 20 from the human 30.

[0043] The observer UAV 100 comprises a fuselage 102 and a controlling system 104 housed in the fuselage 102. The controlling system 104 is configured to control various functions of the observer UAV 100 and may be in the form of a microcontroller, for example, having a processor and a memory. The memory may be configured to store information and/or instructions for directing the processor, and the processor may be configured to execute instructions, such as those stored in the memory.

[0044] An image capture system 106 is mounted to the fuselage 102 and is operatively connected to the controlling system 104. Under the control of the controlling system 104, the image capture system 106 is configured to capture aerial image data of the body of water 40. The image capture system 106 may comprise, for example, one or more cameras and/or video cameras. Further, the observer UAV 100 comprises a communication system 108 housed in the fuselage 102 and which is operatively connected to the controlling system 104. The communication system 108 allows for wireless communication with the operator UAV 200 through any wireless technology such as, for example, Wi-Fi, Bluetooth, or cellular network (e.g. 4G, 5G, etc.). Moreover, the observer UAV 100 comprises one or more speakers and a power supply 112, in the form of a rechargeable battery, for providing power to components of the observer UAV 100.

[0045] The observer UAV 100 also comprises an onboard Global Positioning System (GPS) receiver 114 operatively connected to the controlling system 104 and which is configured to obtain geolocation data of the observer UAV 100.

[0046] Further, the observer UAV 100 has a propulsion system 116 operatively connected to the controlling system 104. In this embodiment, the propulsion system 116 includes four propellers 118 connected to the fuselage 102. Each propeller 118 is configured to be controlled by the controlling system 104 to navigate the observer UAV 100 over the body of water 40.

[0047] The operator UAV 200 will now be described. The operator UAV 200 comprises a fuselage 202 and a controlling system 204 housed in the fuselage 202. The controlling system 204 is configured to control various functions of the operator UAV 200 and may be in the form of a microcontroller, for example, having a processor and a memory. The memory may be configured to store information and/or instructions for directing the processor, and the processor may be configured to execute instructions, such as those stored in the memory. The operator UAV 200 also comprises a power supply 206, e.g., a rechargeable battery, for providing power to components of the operator UAV 200.

[0048] Further, the operator UAV comprises a communication system 208 housed in the fuselage 102 of the operator UAV 200 and which is operatively connected to the controlling system 204. The communication system 208 of the operator UAV 200 allows for wireless communication with the observer UAV 100 for data transmission therebetween. For example, the communication system 208 of the operator UAV 200 may be configured to communicate with the communication system 108 of the observer UAV 100 through any corresponding wireless technology (e.g., Wi-Fi, Bluetooth, or cellular network).

[0049] Further, the operator UAV 200 comprises a sonar device 210 operatively connected to the controlling system 204. Under the control of the controlling system 204, the sonar device 210 is configured to measure underwater sonar data. Moreover, the operator UAV 200 comprises a signal device in the form of an electric field generator 212 having a plurality of electrodes 214a, 214b, 214c and which is operatively connected to the controlling system 204. In this embodiment, the electric field generator 212 comprises three spaced-apart electrodes 214a, 214b, 214c. Under the control of the controlling system 204, the electric field generator 212 is configured to generate a three-dimensional underwater electric field 216 between adjacent electrodes 214a, 214b, 214c when the electrodes 214a, 214b, 214c are immersed in the body of water 40.

[0050] Fig. 3 shows an example of the underwater electric field 216 generated by the three electrodes 214a, 214b, 214c. The underwater electric field 216 is vertically symmetrical and defines an outer peripheral edge 216a and an inner core edge 216b. The underwater electric field 216 has a maximum radius e ₀ on two horizontal optimal planes. In this embodiment, the strength of the underwater electric field 216 at the outer peripheral edge 216a is approximately 9.7 V/m, and the strength of the underwater electric field 216 at the inner core edge 216b is approximately 15.7 V/m. It will be appreciated that the shark 20 will be repelled upon encountering any part of the outer peripheral edge 216a and will not pass any part of the inner core edge 216b. Fig. 3 also shows various parameters utilised in subsequent calculations by the operator UAV 200, in which:

^■ l _e is the vertical distance between the operator UAV 200 and the top of the peripheral edge 216a of the underwater electric field 216;

^■ I _min is the vertical distance between the operator UAV 200 and the surface 42 of the body of water 40 required to maintain the shape of the underwater electric field 216;

^■ U is the vertical distance between the operator UAV 200 and the upper one of the horizontal optimal planes of the underwater electric field 216;

^■ h is the vertical distance between the operator UAV 200 and the lower one of the horizontal optimal planes of the underwater electric field 216;

^■ / _max is the vertical distance between the operator UAV 200 and the bottom of the peripheral edge 216a of the underwater electric field 216; and the relationship of each of the above parameters are given by:

( 1) Imin ^ le ** / 1 ^ k ^ /max

[0051] Further, Fig. 3 shows a radius erh of the underwater electric field 216 on a horizontal plane for a given vertical distance h between the operator UAV 200 and the horizontal plane.

[0052] In some embodiments, the electric field generator 212 may comprise two electrodes. In further alternative embodiments, the electric field generator 212 may comprise four or more electrodes. [0053] Turning back to Fig. 1, the operator UAV 200 further comprises a deployment mechanism 218 mounted to the fuselage 202 and which is operatively connected to the controlling system 204. The deployment mechanism 218 comprises a housing 220 within or near the fuselage 202, an inflatable member 222, and an inflator (not shown) for inflating the inflatable member 222. In this embodiment, the inflatable member 222 is in the form of an inflatable tube 222 having a first end 224 attached to the housing 220 and a second free end 226. The sonar device 210 is attached to the inflatable tube 222 at the second free end 226, and the electric field generator 212 is attached to the inflatable tube 222 between the first end 224 and the second free end 226 such that the electrodes 214a, 214b, 214c of the electric field generator 212 are spaced equidistantly from one another along the inflatable tube 222, with the lowermost electrode 214c being located at or adjacent the second free end 226. In this embodiment, the inflator comprises a replaceable carbon dioxide cartridge and a release valve for allowing fluid communication between the cartridge and the inflatable tube 222.

[0054] In use, the deployment mechanism 218 is configurable between an undeployed configuration and a deployed configuration. In the undeployed configuration, the inflatable tube 222, the sonar device 210 and the electric field generator 212 are all stored within the housing 220. In this embodiment, the inflatable tube 222 is deflated, flaccid and coiled so as to fit within the housing 220. As carbon dioxide is released from the inflator into the inflatable tube 222, the inflatable tube 222 inflates causing the second free end 226 to move downwardly from the housing 220. In the deployed configuration (Fig. 1), the inflatable tube 222 is fully inflated and substantially rigid such that the sonar device 210 and the electric field generator 212 are both spaced from the fuselage. It will be appreciated that the inflator may be designed to allow the deployment mechanism 218 to be configurable between the undeployed configuration and the deployed configuration in a few seconds. It will also be appreciated that the inflatable tube 222 may be designed so as to not affect the manoeuvrability of the operator UAV 200 when the inflatable tube 222 is fully inflated. It will be further appreciated that the inflatable tube 222 may be fully inflated and substantially rigid like a stick, for example, so that the sonar device 210 and electric field generator 212 are in fixed positions relative to the operator UAV 200 during flight.

[0055] The operator UAV 200 also comprises an onboard GPS receiver 228 operatively connected to the controlling system 204 and which is configured to obtain geolocation data of the operator UAV 200. [0056] Further, the operator UAV 200 has a propulsion system 230 operatively connected to the controlling system 204. In this embodiment, the propulsion system 230 includes six propellers 232 connected to the fuselage 202. Each propeller 232 is configured to be controlled by the controlling system 204 to navigate the operator UAV 200 over the body of water 40.

[0057] With reference to Fig. 4, the controlling systems 104, 204 of the operator UAV 200 and the observer UAV 100 are configured to execute instructions to carry out the method operations described hereinbelow.

[0058] The method begins at step 1000, in which the observer UAV 100 surveys the body of water 40 for the presence of a shark 20. In this regard, the controlling system 104 of the observer UAV 100 navigates the observer UAV 100 over the body of water 40 and operates the image capture system 106 to periodically capture aerial image data of the body of water 40. The controlling system 104 of the observer UAV 100 also periodically obtains geolocation data of the observer UAV 100 via the GPS receiver 114 and transmits the obtained geolocation data to the operator UAV 200 via the communication system 108. In this embodiment, the controlling system 204 of the operator UAV 200 receives the geolocation data of the observer UAV 100, via the communication system 208, and navigates the operator UAV 200 over the body of water 40 such that the operator UAV 200 moves with, and spaced at a predetermined distance from, the observer UAV 100 based on the received geolocation data of the observer UAV 100. However, in other embodiments, the operator UAV 200 may not move with observer UAV 100 during surveillance, but may instead be located at a predetermined base station, for example, on the beach.

[0059] At step 1100, the controlling system 104 of the observer UAV 100 identifies the shark 20 in the body of water 40 using image recognition, for example, and calculates positional information of the shark 20 in two-dimensional space, based on the captured aerial image data and the obtained geolocation data of the observer UAV 100 through known methods. In this regard, the positional information includes one or more positions of the shark 20 in two-dimensional space. For example, the controlling system 104 of the observer UAV 100 may calculate a relative position of the shark 20 based on the captured aerial image data and combine the calculated relative position of the shark 20 with the obtained geolocation data of the observer UAV 100 to determine one or more positions of the shark 20 in two- dimensional space. The controlling system 104 of the observer UAV 100 then transmits, via the communication system 108, the positional information of the shark 20 to the operator UAV 200.

[0060] The controlling system 104 of the observer UAV 100 also, at step 1100, identifies an undesired target (i.e., human 30) in the body of water 40 that is closest to the shark 20 using image recognition, for example, and calculates positional information of the human 30 in two- dimensional space, based on the captured aerial image data and the obtained geolocation data of the observer UAV 100 also through known methods. In this regard, the positional information includes one or more positions of the human 30 in two-dimensional space. The controlling system 104 of the observer UAV 100 then transmits, via the communication system 108, the positional information of the human 30 to the operator UAV 200.

[0061] Additionally or optionally, after identifying the shark 20 in the body of water 40, the controlling system 104 of the observer UAV 100 may operate the one or more speakers 110 to transmit a stored audio recording for alerting any identified humans in proximity of the shark 20 of the presence of the shark 20 and instructing the humans to return to the beach. If no human is identified in the body of water 40, the controlling system 104 of the observer UAV 100 may operate the one or more speakers 110 to transmit a stored audio recording for alerting humans on the beach of the presence of a shark 20.

[0062] Subsequently, the controlling system 204 of the operator UAV 200 receives, via the communication system 208, the positional information of the shark 20 and the human 30 from the observer UAV 100. In response to receiving the positional information of the shark 20 and the human 30, the controlling system 204 of the operator UAV 200 navigates the operator UAV 200 over the body of water 40 to an initial deployment position between the shark 20 and the human 30. The initial deployment position is determined by first calculating a horizontal straight-line distance L _xy in two-dimensional space between the positional information of the shark 20 and the human 30, and then comparing the straight-line distance L _xy to a predetermined distance D _xy . In this embodiment, the predetermined distance Z) _vv is based on the maximum radius e ₀ of the underwater electric field 216 and a predetermined distance xa (e.g., 2 metres), as follows: [0063] If the straight-line distance L _xy is equal to or greater than the predetermined distance D _xy , the controlling system 204 of the operator UAV 200 navigates the operator UAV 200 between the shark 20 and the human 30 such that the operator UAV 200 is horizontally spaced from the shark 20 by the predetermined distance D _xy , as shown in Fig. 5(a). The predetermined distance D _xy allows the operator UAV 200 to stay in close proximity to the shark 20, but also at a safe distance from the shark 20 to monitor the movement of the shark 20. If the straight-line distance L _xy is less than the predetermined distance D _yy , the shark 20 is deemed to be in close proximity to the human 30 and the controlling system 204 of the operator UAV 200 navigates the operator UAV 200 between the shark 20 and the human 30 such that the operator UAV 200 is at or near the position of the human 30, as shown in Fig. 5(b).

[0064] The controlling system 204 of the operator UAV 200 also operates the deployment mechanism 218 from the undeployed configuration to the deployed configuration such that the sonar device 210 and the electric field generator 212 are both immersed in the body of water 40. After the sonar device 210 and the electric field generator 212 are immersed in the body of water 40, at step 1200, the controlling system 204 of the operator UAV 200 operates the sonar device 210 to measure underwater sonar data in the body of water 40.

[0065] When the deployment mechanism 218 is in the deployed configuration, the controlling system 204 of the operator UAV 200 operates the electric field generator 212 to generate an underwater electric field 216 in the body of water 40. It will be appreciated that if the initial deployment position of operator UAV 200 is determined to be at or near the position of the human 30, the underwater electric field 216 will surround the human 30 so as to immediately protect the human 30 from any possible attacks by the shark 20.

[0066] Subsequently, at step 1300, the controlling system 204 of the operator UAV 200 determines a predicted path of the shark 20 based on the positional information of the shark 20 and the measured underwater sonar data. In this embodiment, determination of the predicted path is made by identifying the shark 20 in the measured underwater sonar data based on the positional information of the shark 20 and calculating a velocity ¾ of the shark 20 in the body of water 40 in three-dimensional space based on the positional information of the shark 20 and the underwater sonar data. The velocity ¾ of the shark 20 may be calculated based in part on two or more positions of the positional information of the shark 20, for example, a current position of the shark 20 and a past position of the shark 20 over a time period. The predicted path of the shark 20 is then calculated by projecting the velocity t¾ of the shark 20 from a current position of the shark 20.

[0067] The controlling system 204 of the operator UAV 200 then, at step 1400, determines whether the shark 20 is moving towards the human 30. In this embodiment, the controlling system 204 of the operator UAV 200 compares the predicted path of the shark 20 with the positional information of the human 30 to determine whether the shark 20 is moving towards the human 30.

[0068] If, at step 1400, the predicted path of the shark 20 and the positional information of the human 30 do not intersect and the distance between the predicted path of the shark 20 and the positional information of the human 30 increases from the positional information of the shark 20, the shark 20 is deemed to be moving away from the human 30. The controlling system 204 of the operator UAV 200 then, at step 1500, monitors the shark 20 by receiving, via the communication system 208, positional information of the shark 20 and the human 30 from the observer UAV 100 over a subsequent time period, and subsequently navigating the operator UAV 200 between the shark 20 and the human 30 such that the operator UAV 200 is horizontally spaced from the shark 20 by the predetermined distance D _{x y} . It will be appreciated that the method operations of monitoring the shark 20 will be continually performed over subsequent time periods until the shark 20 is at a predefined safe distance (e.g., 3 km) away from the human 30.

[0069] If, at step 1400, the predicted path of the shark 20 and the positional information of the human 30 intersect or the distance between the predicted path of the shark 20 and the positional information of the human 30 decreases from the positional information of the shark 20, the shark 20 is deemed to be moving towards the human 30. The controlling system 204 of the operator UAV 200 then, at step 1600, navigates the operator UAV 200 over the body of water 40 such that the generated underwater electric field 216 is in the predicted path of the shark 20. In this regard, the controlling system 204 of the operator UAV 200 calculates a horizontal interception distance Di _xy based on the horizontal radius of the underwater electric field 216 at the depth z _s of the shark 20 below the surface 42 of the body of water 40, and then navigates the operator UAV 200 to intercept the shark 20 such that the horizontal coordinates O _xy of the operator UAV 200 is in the predicted path of the shark 20 (i.e., in front of the shark 20) and the operator UAV 200 is horizontally spaced from the shark 20 by the interception distance Di _xy . In this embodiment, the calculated interception distance D, _Xi is equivalent to the radius S _(h > of the underwater electric field 216.

[0070] In another embodiment, the controlling system 204 of the operator UAV 200 may also, at step 1300, determine a predicted path of the human 30 based on the positional information of the human 30 and the measured underwater sonar data. In this embodiment, determination of the predicted path may be made by first identifying the human 30 in the measured underwater sonar data based on the positional information of the human 30, calculating a velocity of the human 30 in the body of water 40 in three-dimensional space based on the positional information of the human 30 and the underwater sonar data, and then calculating the predicted path of the human 30 by projecting the velocity v of the human 30 from a current position of the human 30. The velocity of the human 30 may be calculated based in part on two or more positions of the positional information of the human 30, for example, a current position of the human 30 and a past position of the human 30 over a time period. Subsequently, the controlling system 204 of the operator UAV 200 may, at step 1400, determine whether the shark 20 is moving towards the human 30 by comparing the predicted path of the shark 20 and the predicted path of the human 30. For example, if, at step 1400, the predicted path of the shark 20 and the predicted path of the human 30 do not intersect and the closest distance between the predicted path of the shark 20 and a current position of the human 30 is outside of a predetermined intersection distance (e.g., 2 metres), the shark 20 may be deemed to be moving away from the human 30. If, at step 1400, the predicted path of the shark 20 and the predicted path of the human 30 intersect and the closest distance between the predicted path of the shark 20 and a current position of the human 30 is within the predetermined intersection distance, the shark 20 may be deemed to be moving towards the human 30.

[0071] Fig. 6 shows an example of the time of interception /,· where the shark 20 encounters the underwater electric field 216. In this position, the operator UAV 200 is horizontally spaced from the shark 20 by the interception distance D, _xy and the projected horizontal velocity v _sxy of the shark 20, at the horizontal coordinate S _X} of the shark 20, intersects the horizontal coordinates O _xy of the operator UAV 200. It is recognised that upon encountering the outer peripheral edge 216a underwater electric field 216, the shark 20 will be repelled from continuing in the direction of the human 30. Fig. 7 shows various possible turning trajectories μ1, μ2, μ3, μ-4, μ5, μ6 of the shark 20 after encountering the underwater electric field 216 at the time of interception.

[0072] It may also be desirable to intercept the shark 20 where the radius of the underwater electric field 216 is at its maximum as this will maximise the shark’s 20 exposure to the underwater electric field 216. Accordingly, the controlling system 204 of the operator UAV 200 may additionally or optionally determine the optimal vertical distance z ₀ * between the operator UAV 200 and the surface of the body of water 40 that results in the largest possible interception radius e* for a given depth z _s of the shark 20 below the surface 42 of the body of water 40, and navigate the operator UAV 200 to the optimal vertical distance z ₀ *. Figs. 8(a) to 8(d) show various examples of instances of interception where the controlling system 204 of the operator UAV 200 has navigated the operator UAV 200 to the optimal vertical distance z ₀ *. In this embodiment, the optimal vertical distance z ₀ * and the largest possible interception radius ε* may be calculated using piecewise functions, as follows:

[0073] After navigating the operator UAV 200 such that the generated underwater field is in the predicted path of the shark 20, the controlling system 204 of the operator UAV 200 then determines an updated predicted path of the shark 20 based on the positional information of the shark 20 and the measured underwater sonar data. The updated predicted path of the shark 20 is determined in a similar manner described above at step 1300. Subsequently, the controlling system 204 of the operator UAV 200 determines whether the shark 20 is moving towards the human 30 based on the updated predicted path of the shark 20 and the positional information of the human 30 in a similar manner described above at step 1400. [0074] If the shark 20 is deemed to be moving towards the human 30, the controlling system 204 of the operator UAV 200 then navigates the operator UAV 200 over the body of water 40 such that the generated underwater electric field 216 is in the updated predicted path of the shark 20, thereby intercepting the shark 20 in a similar manner described above at step 1600. In some embodiments, the controlling system 204 of the operator UAV 200 may wait for a predetermined time period before each interception so as to avoid the decrease of the shark’s 20 sensitivity to the underwater electric field 216 as result of continuous stimulation.

[0075] If the shark 20 is deemed to be moving away from the human 30, the controlling system 204 of the operator UAV 200 monitors the shark 20 in a similar manner described above at step 1500 until the shark 20 is at the predefined safe distance (e.g., 3 km) away from the human 30. After the shark 20 is determined to be at the predefined safe distance away from the human 30, at step 1700, the controlling system 204 of the operator UAV 200 navigates the operator UAV 200 to the predetermined base station for replacement of the carbon dioxide cartridge and recharging of the battery.

[0076] In an alternative embodiment, the deployment mechanism 218 may instead comprise an electric reel, and a tether having a first end attached to the reel and a second free end. The tether may be, for example, a rope, a cord or the like. The sonar device 210 may be attached to the tether at the second free end and the electric field generator 212 may be attached to the tether between the first end and the second free end. In the undeployed configuration, the tether may be coiled on the reel and the sonar device 210 and the electric field generator 212 may be disposed within or near the fuselage 202. In the deployed configuration, the tether may be uncoiled from the reel such that both the sonar device 210 and the electric field generator 212 may be spaced from the fuselage.

[0077] In another alternative embodiment, the operator UAV 200 may not comprise a sonar device. With reference to Fig. 9, the controlling systems 104, 204 of the operator UAV 200 and the observer UAV 100 of this embodiment is configured to execute instructions to carry out the method operations similar to that of Fig. 4 and like features/steps have been indicated with like reference numerals. However, in this embodiment, at step 1300’, the controlling system 204 of the operator UAV 200 determines a predicted path of the shark 20 based on the positional information of the shark 20 only. In this embodiment, determination of the predicted path is made by first calculating a velocity of the shark 20 in the body of water 40 in two-dimensional space based on the positional information of the shark 20. The velocity of the shark 20 may be calculated based in part on two or more positions of the positional information of the shark 20, for example a current position of the shark 20 and a past position of the shark 20 over a time period. The predicted path of the shark 20 is then calculated by projecting the velocity of the shark 20 from a current position of the shark 20.

[0078] In other embodiments, the signal device may be in the form of a light emitter that is configured to emit light in the body of water. It will be appreciated that the emitted light will be of a particular frequency that can cause the shark to be irritated and turn away upon encountering the emitted light. In yet other embodiments, the signal device may be in the form of an acoustic generator that is configured to emit an acoustic signal in the body of water. It will be appreciated that the emitted acoustic signal will be of a particular frequency that can cause the shark to be irritated and turn away upon encountering the emitted acoustic signal. In further alternative embodiments, the signal device may comprise any combination of a light emitter, an electric field generator and an acoustic generator.

[0079] In other embodiments, the undesired target may instead be the beach due to there being no humans in proximity to the shark 20. In this regard, the controlling system 104 of the observer UAV 100 may identify the beach based on the aerial image data and calculate positional information of the beach in two-dimensional space, and subsequently transmit, via the communication system 108, the positional information of the beach to the operator UAV 200. It will be appreciated that the above method operations of deploying the operator UAV 200 and intercepting the shark 20 may be performed in respect of the beach.

[0080] In other embodiments, the system may employ a single UAV to carry out all of the above described method operations.

[0081] The embodiments described above has numerous advantages. For example, the system 10 provides an effective and efficient means for actively identifying a shark 20 in a body of water 40 and intercepting the identified shark 20 to repel the shark 20 from any human 30 in proximity to the shark 20. In this regard, the system 10 intercepts the shark 20 only if it is determined whether the shark 20 is moving towards the human 30. Further, the system 10 repels the shark 20 using the underwater electric field 216 without capturing or causing harm to the shark 20 and other marine animals. The operator UAV 200 is capable of re-positioning itself between the shark 20 and the human 30 at any given time to ensure that the shark 20 is repelled away from the human 30.

[0082] In some embodiments, the system may employ a plurality of operator UAVs in communication with one or more observer UAVs. In such a system, one of the plurality of operator UAVs will be allocated to one identified marine animal in the body of water 40. This allows multiple marine animals to be intercepted and repelled at any given time.

[0083] It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.