Methods of operating an unmanned aerial vehicle; mobile airbase for unmanned aerial vehicle

Abstract

A method of providing a prescription map for distribution of an agricultural product to an area (200, 210) by means of a distribution unmanned aerial vehicle ("distribution UAV", 1) comprises providing a preliminary map of the area (200, 210); using the preliminary map to define a preliminary path (20a, 20b) for the distribution UAV to fly in order to sufficiently distribute the product over the area (200, 210); operating a reconnaissance UAV (1000) to fly over the area (200, 210) while detecting obstacles (21, 22, 23); and adapting the preliminary path (20a, 20b) based on the obstacles (21, 22, 23) so as to provide a prescription path (20a', 20b').

Description

[0001] METHODS OF OPERATING AN UNMANNED AERIAL VEHICLE; MOBILE AIRBASE FOR UNMANNED AERIAL VEHICLE

[0002] Technical field

[0003] The present disclosure relates generally to the use of unmanned aerial vehicles (“UAVs”) in agriculture, and in particular to distribution of one or more products in liquid, powder or granular form to an area over which the UAV flies.

[0004] Background

[0005] In agriculture it is common to use added product or substance, such as fertilizer, fungicide, herbicide or pesticide to improve the yield from the crops or to prevent weeds or pests. Other products may include minerals, chalk or seeds. The product may be in granulated, powdered, or liquid form.

[0006] Different distribution techniques exist for product of the different forms. The product is commonly spread from agricultural implements which may be mounted on, or towed behind, a tractor or other type of self-propelled vehicle. In some areas, airborne spreading is practiced by airplanes or helicopter, however, such practices are costly, and in many areas, such practices are not permitted.

[0007] Moreover, airborne spreading is generally associated with a lack of precision, due to the height and speeds at which it is carried out.

[0008] A common problem for traditional spreading techniques is the inevitable tramlines needed. Tramlines decrease the arable field area and increase soil compaction locally.

[0009] Moreover, ground-based spreading may be difficult when fields are wet, as machines tend to sink and get stuck. Also, tramlines tend to further erosion, in particular on sloping fields, where soil is led away by water flowing in the tramlines.

[0010] Another common problem for the spreading techniques is the effect from wind, which may interfere with the desired throwing pattern from a centrifugal spreader, or with the mist created from a liquid spreadingimplement, in a negative way. Rain may also cause problems, limiting the ability for tractors or other ground-based vehicles to get traction in field.

[0011] Hence, there has arisen an interest in the use of UAVs or “drones” equipped with spreader units for spreading various products.

[0012] While one line of development in the field of agricultural UAVs is to use a large number of small UAVs, another line of development is to use fewer but larger UAVs. For example, a larger UAV for distribution of agricultural product may have a distribution width of about 10-15 m and a load capacity of about 100-1000 kg.

[0013] However, the use of UAVs in agriculture is still in its infancy and hence there is a need for improvements in their capabilities, operation and in their precision.

[0014] Summary

[0015] It is an objective of the present disclosure to provide solutions which eliminate or alleviate at least some of the disadvantages mentioned above. A particular provide solutions that allow the use of larger UAVs for distribution of a product to an area.

[0016] The invention is defined by the appended independent claims.

[0017] Embodiments are set forth in the appended dependent claims, in the following description and in the attached drawings.

[0018] According to a first aspect, there is a method of providing a prescription map for distribution of an agricultural product to an area by means of a distribution unmanned aerial vehicle (“distribution UAV”), the method comprising providing a preliminary map of the area; using the preliminary map to define a preliminary path for the distribution UAV to fly in order to sufficiently distribute the product over the area; operating a reconnaissance UAV to fly over the area while detecting obstacles; and adapting the preliminary path based on the obstacles so as to provide a prescription path.

[0019] An agricultural product is defined as a product that is to be distributed in the course of agriculture. In most cases, the product will be solid or liquid,but a gaseous product is not excluded. For example, the product may be one or more of seeds, fertilizer, pesticide, insecticide, fungicide, or the like.

[0020] A prescription map is a map defining how a product is to be distributed over an area, such as a field or a plantation. The prescription map may comprise a prescription path indicating how the distribution UAV is to move over the area.

[0021] The prescription map may also comprise indications on how the distribution is to be controlled along the prescription path. For example, it may be desirable to wholly or partially shut off distribution in order to avoid overlap at certain parts of the area. It may also be desirable to distribute different amount of product to different parts of the area.

[0022] The preliminary map may be provided in the form of a standard prescription map, or it may be provided from scratch, e.g. from a Google® map, or the like.

[0023] The preliminary path may be manually or automatically generated. The reconnaissance UAV may be a dedicated UAV for detection of obstacles, having the appropriate sensors, such as camera, radar, lidar, ultrasonic, laser, or the like. Alternatively, the distribution UAV may be used in a reconnaissance mode, whereby appropriate sensors are arranged on the distribution UAV.

[0024] The reconnaissance UAV may be another UAV than the distribution UAV. The reconnaissance UAV may require less energy than the distribution UAV to fly a specific route.

[0025] Obstacles may be any type of obstacle which may interfere with the flight of an UAV, including, but not limited to: trees, shrubberies, hills, rocks, power lines, telephone lines, towers (e.g. for cellular telephony or wind power), buildings, fences, water towers, or the like.

[0026] The use of a prescription map is particularly advantageous when using larger UAVs, which may be less agile and more likely to be interfered with by external obstacles.The use of a reconnaissance UAV may be advantageous when the reconnaissance UAV requires less power than the distribution UAV to fly along the preliminary path.

[0027] The prescription maps and the reconnaissance data received during the reconnaissance flight may be processed on a computer which is external to the UAV, such as on a work station situated on a mobile airbase or remotely.

[0028] Accordingly, there is provided a method of providing a prescription map that can be effectively used for controlling a large UAV to accurately distribute a product to an area while the UAV flies over the area.

[0029] The reconnaissance UAV may be operated to fly along the preliminary path.

[0030] The preliminary path may be a meandering path as seen in a 2D ground plane.

[0031] The detecting obstacles may comprise recording a plurality of obstacles by 3D position and extent.

[0032] The method may further comprise updating the preliminary map with the obstacles, so as to provide the prescription map.

[0033] The updating the preliminary map may comprise providing a 3D map, wherein said obstacles are indicated by 3D position and extent.

[0034] The updating the preliminary map may comprise adding ground level along the preliminary path.

[0035] The adapting the preliminary path may comprise adjusting a lateral and / or vertical position of the preliminary path so as to avoid the obstacles.

[0036] According to a second aspect, there is provided a method of operating a distribution UAV for distribution of an agricultural product to an area, comprising providing a prescription map according to the method of any one of the preceding claims, and operating the distribution UAV to fly according to the prescription path of the prescription map while distributing at least one product.

[0037] The UAV may be operated to distribute the at least one product in accordance with the prescription map.According to a third aspect, there is provided a method of operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area, comprising receiving a prescription map, indicating a distribution area and at least one distribution path along which said distribution is to take place, wherein the distribution path comprises at least one distribution path segment, along which an even distribution groundspeed is desired, said distribution path segment having a starting point and an end point and extending substantially linearly between said starting point and said end point, receiving a position indicating a velocity check waypoint, which is aligned with the distribution path segment and positioned a predetermined distance from the starting point. In the method, the UAV is operated such that when the UAV reaches the velocity check waypoint, the UAV is caused to adjust its groundspeed, such that a predetermined distribution groundspeed is achieved at the starting point, and the predetermined distribution groundspeed is maintained along the distribution path segment.

[0038] A velocity check waypoint is a waypoint at which velocity and direction of the UAV is verified and, if needed, adjusted. The velocity check waypoint is situated sufficiently far away from the starting point, such that the UAV will have accelerated to the predetermined distribution groundspeed by the time the UAV reaches the starting point.

[0039] Hence, the method provides a way of ensuring that the distribution groundspeed of the UAV is as close as possible to what is desired for the distribution of the product.

[0040] The UAV may be operated to start distribution at the starting point and / or to cease distribution at the end point and / or to vary the distribution along the distribution path segment.

[0041] The method may further comprise controlling an output rate of at least one of the distribution units of the UAV in dependence of an actual groundspeed and / or in dependence of the prescription map.

[0042] According to a fourth aspect, there is provided a method of operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area over which the UAV travels, comprising receiving a prescription map,indicating a distribution area and at least one distribution path along which said distribution is to take place, operating the UAV to fly along the distribution path while distributing the product, and interrupting the flight at an interrupt point between a path start and a path finish, operating the UAV to return to an airbase, and operating the UAV to resume the distribution path while distributing the product. The method further comprises operating the UAV to proceed from the interrupt point to the airbase along a first path, and operating the UAV to proceed from the airbase towards the interrupt point along a second path, different than the first path, while distributing the product along at least a portion of the second path.

[0043] The UAV may be operated to be oriented in a predetermined working orientation while flying along a working direction, and wherein the UAV is operated to fly in a reverse orientation while flying along the first path.

[0044] The second path may comprise a portion of the distribution path that had not been travelled prior to the UAV 1 reaching the interrupt point.

[0045] According to a fifth aspect, there is provided a method of operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area over which the UAV travels, comprising operating the UAV to land on a landing platform forming part of the airbase, and causing the landing platform with the UAV, and a replenishing interface of the airbase to translate at least partially horizontally relative to each other, such that the replenishing interface is brought into contact with a corresponding interface on the UAV.

[0046] By translating the UAV horizontally, it is possible to bring it into connection with a fixed replenishing interface, thus enabling the provision of a replenishing interface comprising an auger type product feeder.

[0047] The horizontal translation may in particular be along a horizontal longitudinal direction of the airbase.

[0048] The method may further comprise receiving a prescription map, indicating a deposition area and at least one distribution path along which said distributing is to take place, operating the UAV to fly along the distribution path while distributing the product, and operating the UAV to return from the distribution path to an airbase.The method may further comprise securing the UAV to the landing platform prior to the translation.

[0049] The replenishing interface may comprise at least one fuel delivery channel and at least one product delivery channel.

[0050] The product delivery channel may comprise an auger type conveyor. An auger type conveyor may be advantageous if the product is solid, granular or powder product.

[0051] The product delivery channel may comprise hoses or tubes for delivery of liquid product. The replenishing interface may comprise hose or tube connections, e.g. male orfemale connecting ends, that come into connection with corresponding hose or tube connections on the interface of the UAV when the replenishing interface is brought into contact with the corresponding interface of the UAV.

[0052] The product delivery channel may comprise hose or tube connectors for transfer of liquid product.

[0053] The method may further comprise weighing of the UAV at landing on the airbase.

[0054] The method may further comprise weighing of the UAV at takeoff from the airbase.

[0055] The weighing may indicate the level of product replenished to the UAV. The weighing may prevent the UAV from liftoff if loaded too heavy.

[0056] The UAV may be caused to land with a UAV forward direction facing outwardly of the airbase.

[0057] Hence, where the landing platform is situated at a rear portion of the airbase, the UAV will face backwards, as seen from the landing platform.

[0058] In the event a landing platform is situated at a front portion of the airbase, then the UAV will face forwards.

[0059] The UAV may be operated to be oriented in a predetermined working orientation while flying along a working direction, and wherein the UAV is operated to fly in a reverse orientation while returning from the distribution path to an airbase.The UAV may be operated to land on the landing platform with the landing platform in a landing position, and the at least partially horizontal translation may bring the landing platform towards a filling position.

[0060] Operating the UAV to land may comprise sliding the UAV on a guide device of the landing platform to guide the UAV towards a specific position of the landing platform.

[0061] The guide device may surround a projected size and shape of a landing gear of the UAV.

[0062] According to a sixth aspect, there is provided a mobile airbase for an agricultural unmanned aerial vehicle, “UAV”, the airbase comprising a frame, at least one ground support, in particular a wheel, rotatably connected to the frame, at least one landing platform, configured for receiving the UAV, at least one product supply, configured for supplying at least one product to be distributed by the UAV. The landing platform is horizontally movable relative to the frame between a landing- and takeoff position and a filling position.

[0063] The landing- and takeoff position is a position at which the landing platform is situated when the UAV is to take off or land.

[0064] The filling position is a position where the UAV is to be replenished with product and / or fuel.

[0065] The landing platform may be horizontally slidably connected to the frame.

[0066] The landing platform may be connected to the frame by a parallel linkage connection.

[0067] The landing platform may be horizontally rollable on the frame.

[0068] The landing platform may be rotatable in a horizontal plane relative to the frame.

[0069] A replenishing interface may comprise at least one fuel delivery channel and at least one product delivery channel.

[0070] The product delivery channel may comprise an auger type conveyor. The replenishment interface may be configured to be disconnected from a corresponding interface of the UAV when the landing platform is in thelanding- and takeoff position, and to be connected to the corresponding interface of the UAV when the landing platform is in the filling position.

[0071] The landing platform may be positioned at a vertical distance from a lower floor of the airbase which is about 20-80 % of a total distance between the lower floor and an upper floor of the airbase, preferably about 30-70 % or about 40-60 %.

[0072] Such position of the landing platform can be provided regardless of whether the landing platform is horizontally movable relative to the frame between a landing- and takeoff position and a filling position.

[0073] The airbase may further comprise at least one collection trough, sized and adapted to extend horizontally below at least one zone where a potentially harmful substance, such as fuel or product is being handled.

[0074] Such collection trough can be provided regardless of whether the landing platform is horizontally movable relative to the frame between a landing- and takeoff position and a filling position.

[0075] The airbase may further comprise at least one landing cradle, configured for receiving the UAV 1 at a predetermined position relative to the landing platform.

[0076] The landing cradle may comprise a latching device for latching the UAV to the landing platform. The airbase may further comprise side panels pivotably moveable between a closed state and an upfolded state. The side panels may provide a horizontal operator platform for supporting an operator in an upfolded state.

[0077] According to a seventh aspect, there is provided a method of landing an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area over which the UAV travels, on a landing platform of a mobile airbase, comprising operating the UAV to fly autonomously in accordance with a satellite-based navigation system, operating the UAV to fly to a position of the airbase, using a camera on the UAV to receive images representing the airbase, identifying at least one machine-readable indicator on the airbase, and using the machine-readable indicator to guide the UAV to the landing platform.The landing strategy provides a way of combining the large area navigation used while performing agricultural tasks with the UAV, with a higher precision navigation required near the landing platform.

[0078] The method may further comprise using at least one supplementary radio-based navigation beacon, located on the mobile airbase, to enhance accuracy of the satellite-based navigation system.

[0079] The method may further comprise orienting the UAV such that a front end of the UAV faces rearwardly of the airbase.

[0080] Operating the UAV to fly autonomously may comprise distributing an agricultural product to an area.

[0081] Distributing an agricultural product to an area may comprise operating the UAV to fly in straight, non-overlapping paths back-and-forth across the area.

[0082] The method may further comprise terminating, or interrupting, the distribution of agricultural product.

[0083] The method may further comprise replenishing the UAV with agricultural product and / or fuel while the UAV is on the landing platform.

[0084] According to an eighth aspect, there is provided method of operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area over which the UAV travels, the method comprising providing a mobile airbase comprising a landing platform configured to receive the UAV, providing a ground controller, in communication with the UAV, providing a manually operable safety breaker, in communication with the ground controller, the safety breaker being located at a position sufficiently spaced from the landing platform. The ground controller is configured to communicate with the UAV to prevent the UAV from landing on the landing platform in case the safety breaker is not being operated.

[0085] The UAV may be configured for autonomous landing on the landing platform.

[0086] The mobile airbase may comprise at least one biological sensor, configured for detecting presence of living creatures in the vicinity of the mobile airbase, and wherein the method comprises allowing the UAV to landon the landing platform without the safety breaker being operated only when no movement is detected by the at least one biological sensor.

[0087] The safety breaker may be mounted on the mobile airbase, either directly or by wire.

[0088] The ground controller and the safety breaker may be arranged in different physical components.

[0089] According to a ninth aspect, there is provided a mobile airbase for operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area over which the UAV travels, the airbase comprising a frame, at least one ground support, in particular a wheel, rotatably connected to the frame, a pair of landing platforms, each configured for receiving the UAV, at least one product supply, configured for supplying at least one product to be distributed by the UAV. The airbase presents a generally elongated shape along a travel direction thereof. A first one of the landing platforms is located at a front portion of the airbase. A second one of the landing platforms is located at a rear portion of the airbase.

[0090] The product supply may be positioned between the landing platforms, as seen in a longitudinal direction of the airbase.

[0091] At least one of the landing platforms may be horizontally movable relative to the frame.

[0092] The first one of the landing platforms may be situated at a forwardmost part of the frame, optionally with only a tow bar extending forwardly of the first one of the landing platforms.

[0093] The second one of the landing platforms may be situated at a rearmost part of the frame.

[0094] The airbase may further comprise at least one fuel supply, configured for supplying liquid fuel to the UAV.

[0095] The product supply may comprise an auger type conveyor, configured for supplying a granulated solid product.

[0096] According to a tenth aspect, there is provided a method of operating a set comprising at least two unmanned aerial vehicles, “UAV”, for distributing an agricultural product to an area over which the UAV travels, the methodcomprising providing a mobile airbase comprising a primary landing platform configured to receive one of the UAVs; a ground controller, configured to communicate with a respective flight controller of the UAVs. The method comprising preparing a secondary landing site, comprising selecting a secondary landing site in the vicinity of the airbase and at a safe distance from the airbase; providing at least one dedicated passive optical marker at the secondary landing site; and optionally fencing off the secondary landing site; wherein the ground controller determines if a first one of the UAVs is present at the primary landing platform; wherein the ground controller determines if a second one of the UAVs is incoming for landing; and if the primary landing platform is empty of any UAV, then directing the second one of the UAVs to the primary landing platform; and if the first one of the UAVs is present at the primary landing platform, then directing the second one of the UAVs to the secondary landing site.

[0097] The passive optical marker may be detectable by the UAVs to provide landing route guidance.

[0098] By landing route guidance is hereby meant a preferred flight path the UAV may fly between the point of detecting the passive optical marker and landing on the secondary landing site. The passive optical marker may be detectable by the means of a camera.

[0099] The method may further comprise, if the second one of the UAVs is directed to the secondary landing site, directing the second one of the UAVs to the primary landing platform when the first one of the UAVs is not present at the primary landing platform.

[0100] According to an eleventh aspect, there is provided a product supply system, comprising a product tank having at least two product compartments, configured for holding a respective solid bulk product, a product feeder, configured for feeding the solid bulk product from the product tank. The product supply comprises a respective compartment feeder, configured for feeding the product held in the respective compartment towards the product feeder. The compartment feeders are individually controllable.Such product supply system can be provided on a mobile airbase regardless of whether the landing platform is horizontally movable relative to the frame between a landing- and takeoff position and a filling position.

[0101] The product supply system may be used to feed different solid products to an UAV using a single product feeder.

[0102] The system may further comprise at least one closure, configured for selectively preventing product from one of the compartments from reaching the product feeder.

[0103] At least one of the compartment feeders may comprise an auger.

[0104] The product feeder may comprise an auger.

[0105] At least one of the compartment feeders may be configured for feeding the product in an essentially horizontal direction.

[0106] Essentially horizontal may hereby mean plus / minus 30 degrees from a horizontal plane, preferably plus / minus 20 degrees, plus / minus10 degrees, plus / minus 5 degrees or plus / minus 1 degree.

[0107] The product feeder may be configured for elevating the product to a higher vertical level.

[0108] According to a twelfth aspect, there is provided an airbase as described above, wherein the product supply comprises a product supply system as described above.

[0109] According to a thirteenth aspect, there is provided a method of operating the product supply system as described above for feeding an agricultural product to an unmanned aerial vehicle, “UAV”, for distributing the product to an area over which the UAV travels. The method comprises operating the product feeder to feed the product to a product tank of the UAV, operating one of the compartment feeders to feed the product to the product feeder, receiving an indication that a predetermined product level of the product tank has been reached, stopping feeding by said one of the compartment feeders, and continuing feeding by the product feeder for a time sufficient to empty the product feeder of the product.

[0110] According to a fourteenth aspect, there is provided a method of operating the product supply system as described above for feeding anagricultural product to an unmanned aerial vehicle, “UAV”, for distributing the product to an area over which the UAV travels. The method comprises operating the product feeder to feed the product to a product tank of the UAV, operating one of the compartment feeders to feed the product to the product feeder, receiving an indication that a predetermined product level of the product tank has been reached, operating the closure to stop feeding to the product feeder, and continuing feeding by the product feeder for a time sufficient to empty the product feeder of the product.

[0111] According to a fifteenth aspect, there is provided a product tank for use in a UAV, in particular for a solid material, in particular granular or powdery material, comprising a tank body, which provides an enclosed product space, a product inlet, at an upper portion of the tank body, a product outlet, at a lower portion of the tank body, at least one input feeder, provided at the upper portion of the tank body and having a length, along a longitudinal direction thereof, extending over at least 1 / 3, preferably at least , at least % or the entire length of the upper portion of the tank body.

[0112] The product tank may be provided as an exchangeable module for connection to a UAV, in particular for quick connection and disconnection to the UAV.

[0113] However, the product tank may also be provided as a fixed installation on a UAV, thus providing a dedicated UAV.

[0114] By positioning an input feeder at the upper portion of the tank body, it is possible to control the distribution of the product in the tank, even where the tank is of relatively small height.

[0115] The input feeder may extend approximately along a working direction of the product tank and of the UAV that is to carry the product tank.

[0116] The product tank may have at least two input feeders, preferably extending in parallel with each other and more preferably in the same plane.

[0117] The input feeder(s) may comprise at least one auger-type conveyor. The product input auger may be freely rotatably arranged relative to the tank body, in particular, there may not be any drive unit for driving the input auger provided at the product tank.The product tank may have a maximum width, a maximum length and a maximum height, with the maximum length being greater than the maximum height.

[0118] The product tank may further comprise at least one output feeder, at the lower portion of the tank body.

[0119] The output feeder may comprise at least one auger-type conveyor. The output auger may present a varying displacement along a rotation axis thereof.

[0120] The output auger may present at least two output auger sections, which are juxtaposed along the rotation axis, and which may be individually controllable.

[0121] The product tank may further comprise an output auger cover, which is varying or variable along a rotation axis of the output auger.

[0122] According to an sixteenth aspect, there is provided a system comprising a replenishment device and the product tank as described above, wherein the replenishment device comprises a replenishment product tank and a replenishment feeder, configured to convey product from the replenishment product tank to the UAV product tank, wherein the replenishment feeder comprises a drive unit, and wherein the replenishment feeder is connectable to the input feeder, such that the input auger is drivable by the replenishment feeder.

[0123] In the system, the replenishment product tank may comprise a main product tank and an intermediate product tank, with the replenishment feeder configured to output product from the intermediate product tank.

[0124] Hence, the speed of loading product to the product tank may be increased.

[0125] The replenishment device may comprise at least two replenishment feeders, connectable to a respective one of at least two input feeders.

[0126] Drawings

[0127] Figs 1a-1b schematically illustrate an UAV and a mobile airbase.

[0128] Figs 2a-2c schematically illustrate a prescription map.Figs 3a-3b schematically illustrate a prescription map.

[0129] Figs 4a-4b schematically illustrate a prescription map.

[0130] Figs 5a-5b schematically illustrate a mobile airbase having a displaceable landing platform.

[0131] Fig. 6 illustrates a side view of the UAV.

[0132] Fig. 7 schematically illustrates a side view of a mobile airbase having two landing platforms.

[0133] Fig. 8 schematically illustrates a top view of a mobile airbase with a secondary landing site.

[0134] Figs 9a-9b schematically illustrate a cross sectional view of a part of the airbase 3.

[0135] Fig. 10a schematically illustrates a landing cradle.

[0136] Fig. 10b schematically illustrates a latching arrangement.

[0137] Figs 11 a-11 b schematically illustrate a product tank.

[0138] Figs 12a-12d schematically illustrate a replenishment system.

[0139] Detailed description

[0140] Throughout this specification, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

[0141] The terms "a" and "an" are used herein to refer to one or to more than one (i.e. to at least one) of the grammatical object of the article. By way of example, "an element" means one element or more than one element.

[0142] In the context of this specification, modifying terms, such as "about", “approximately” and “substantially” are understood to refer to a range of numbers that a person of skill in the art would consider equivalent to the recited value in the context of achieving the same function or result. Any value, range or term thus modified is to be understood as being disclosed also without the modifying term.Referring to fig. 1a, an unmanned aerial vehicle (“UAV”) 1, commonly known as a “drone”, is an aircraft that operates without a human pilot on board. UAVs can be controlled remotely by a human operator and / or autonomously by onboard computers.

[0143] While UAVs may come in many different designs and configurations, in the present disclosure, the UAV will, as a non-limiting example, be assumed to comprise the following systems.

[0144] An UAV 1 would typically comprise an airframe 11 , i.e. the structure of the UAV, which includes the body, wings (if any), and landing gear 113. It provides the necessary support and shape for the drone. In the illustrated example, the airframe comprises a central and generally horizontally extending web 111 and a pair of generally horizontally extending flanges 112, end portions of which provide comers of a rectangle at which rotors are positioned.

[0145] An UAV 1 would typically also comprise a propulsion system 121, 122, which would include the motor(s)121, rotor(s) 122, and sometimes jet engines, which generate the thrust needed for the UAV 1 to fly.

[0146] The propulsion system may also comprise a transmission system (not shown), for transferring mechanical power from one or more motors 121 to one or more rotors 122.

[0147] An UAV 1 would typically also comprise a power source 13, such as a battery or fuel system that provides the energy required to power the UAV’s systems and propulsion.

[0148] An UAV 1 would typically also comprise a flight control system 14, which would include the onboard computer and sensors (such as gyroscopes and accelerometers) that help stabilize and control the UAV during flight.

[0149] An UAV 1 would typically also comprise a communication system 15, which allows the UAV to communicate with the ground control station (ground controller 40) or operator, enabling remote control and / or data transmission.

[0150] An UAV 1 would typically also comprise a navigation system 16, including Global Navigation Satellite System (GNSS) and / or other sensors that help the UAV 1 determine its position and navigate to its destination.The navigation system may also include gyro(s) and accelerometer(s) for inertial navigation, which may be used in case of limited availability of GNSS.

[0151] An UAV 1 would typically also comprise a payload 17, which, depending on the UAV’s purpose, can include cameras, sensors, delivery packages, or other equipment that the UAV is designed to carry.

[0152] An UAV 1 may comprise a local beacon detector 18, which may be used for connecting to and navigating by a local beacon 181.

[0153] An UAV 1 may also comprise one or more cameras 19 for capturing images that can be used for manual flight, for navigation and / or for inspection. In particular, it may be desirable to provide one or more cameras having night vision capability, e.g. by having capability to pick up light in the infra-red spectrum.

[0154] In particular, one or more cameras 19 may be positioned to provide a view of a spreader unit, such that the distribution operation can be monitored, either in real-time or later.

[0155] The UAV 1 may also have one or more sensors for collision avoidance, such as radar sensors, lidar sensors, ultrasound sensors, laser sensors or cameras.

[0156] The various systems controlling the flight, navigation, communication and operation of the UAV 1 may be provided as separate systems, or as a wholly or partially integrated system, collectively referred to as a “onboard controller” 14, 15, 16.

[0157] A special case may be that the payload 17 has its own control system, although such control system would need to communicate with the onboard controller 14, 15, 16 or with the ground controller 40, e.g. when a need to replenish product is detected. An UAV 1 would typically also require a controller 40, which comprises the interface used by the operator to control the UAV, which can be a handheld controller, a computer, or a more complex setup for larger UAVs.Typically, all actuators and / or sensors may be connected to the onboard controller, to enable the onboard controller to make autonomous decisions and / or for communication to / from the ground controller 40.

[0158] In some embodiments, communication may be only between the UAV 1 and the airbase 3, with all control functions being provided at the airbase 3, e.g. through the ground controller 40. In such embodiments, on-site operator control and / or supervision would be necessary.

[0159] In some embodiments, additional communication may be to a central control and / or monitoring site, such as via a direct communication link or via a cloud-based system. In such embodiments, the airbase 3 may operate as a gateway, such that the UAV 1 communicates with the airbase 3 and the airbase 3 forwards communication to / from the UAV 1 from / to a remote control site. In such embodiments, an operator could control and / or monitor several airbase / UAV systems remotely and / or ambulatory.

[0160] In some embodiments, the airbase 3 and the UAV 1 may both communicate with a central control site, such as via a direct communication link or via a cloud-based system. This would also allow an operator to control and / or monitor several airbase / UAV systems remotely and / or ambulatory.

[0161] The communication may utilize cellular and / or satellite-based communication technology. Optionally wlan functionality may be used by the airbase 3, if available where the airbase 3 is stationed.

[0162] Data processing and / or storage may be provided at the airbase 3, in a remote server and / or control site and or by cloud-based computing / storage.

[0163] In the present context, it is contemplated that the UAV 1 would be sized and adapted for payloads 17 in excess of 100 kg, preferably in excess of 200 kg or in excess of 400 kg. Such UAV platforms are commercially available, e.g. in a quadcopter configuration with a generally H-shaped airframe and a petrol- or jet fuel-powered turboshaft engine.

[0164] The payload may comprise a spreader device 171 for spreading a liquid or solid product to ground over which the UAV travels. The spreader device 171 may comprise one or more product tanks 170, a spreader unit 1711 and a spreader unit support 1712, which extends such that the spreaderunit 1711 is situated outside an area of downwash from the rotors 122. The spreader unit 1711 may comprise one or more spreader discs (not shown) for spreading a solid (powdery or granular) product, such as fertilizer, pesticide, herbicide, fungicide, seeds, ora combination thereof. Alternatively, the spreader unit 1711 may comprise a sprayer boom for spreading a liquid product, such as fertilizer, pesticide, herbicide, fungicide, or a combination thereof.

[0165] The product tank 170 may be provided with a product level sensor. For example a weight sensor, a pressure sensor, an optical sensor, a radar sensor, a lidar sensor, a magnetic sensor or an ultrasonic sensor may be used to detect the level of solid product in the product tank 170.

[0166] Hence, the UAV 1 may detect a low product level in the product tank 170, which may trigger the UAV 1 to return to the airbase 3 for replenishment.

[0167] As illustrated, the spreader device 171 may extend outside the downwash area from the rotors 122, such that the spreader device also defines a forward working direction Dw of the UAV 1. Optionally, the spreader device 171 may also extend downwardly from the UAV, preferably below a landing gear 113. Hence, the spreader device 171 extends outwardly from the airframe 111, 112 towards a direction which is the working direction Dw.

[0168] Alternatively, the product level sensor may be dispensed with. Instead a product feed sensor may be provided in the spreader unit, e.g. in the form of a detector (typically optical or acoustic) for detecting flow of the product in the channel of the spreader unit 171.

[0169] Hence, the UAV 1 may detect that the product flow in the channel has ceased, which may trigger the UAV 1 to return to the airbase 3 for replenishment.

[0170] Referring to fig. 1b, there is illustrated a mobile airbase 3 with a UAV 1 received at a landing platform 31 of the mobile airbase 3.

[0171] The mobile airbase 3 comprises a landing platform 31, which is supported by a frame 32. The frame 32 may provide one or more floors, such as a lower floor 321 and an upper floor 322. In the illustrated example, thelanding platform 31 is provided nearer the upper floor 322 than the lower floor 321.

[0172] The landing platform 31 may comprise an optional guide device (not shown). The guide device may guide a UAV 1 to a specific position of the landing platform 31 during landing.

[0173] The guide device may surround a specific landing position of the landing platform.

[0174] The specific position may correspond in size and shape to a projected size and shape of a landing gear 113 of the UAV 1 , such that the UAV 1 may be securely held in place in horizontal direction to the specific position.

[0175] The specific position may be a center of the landing platform.

[0176] The guide device may comprise angled surfaces which may be angled to form a cone or funnel shape towards said specific position.

[0177] The guide device may aid the UAV 1 to land at the specific position during for e.g. hard wind.

[0178] The guide device may be angled about 20-90 degrees towards the specific position, preferably 30-60 degrees or 40-50 degrees.

[0179] The guide device may comprise sliding surfaces. Such sliding surfaces may be foldable between a flat position and an angled position.

[0180] The folding may be operated by at least one actuator, such as a hydraulic actuator or an electric actuator, in communication with a ground controller 40. Said a least one actuator may be operably coupled between the sliding surfaces and the landing platform 31.

[0181] The sliding surfaces may be brought from the flat position to the angled position by the weight of the UAV 1 and a balancing mechanism arranged in the landing platform 31. The weight of the UAV 1 may cause the balancing mechanism to receive the UAV 1 in a damped manner and transfer the weight of the UAV 1 to a lifting force which folds the sliding surfaces to angled position.

[0182] Alternatively, the sliding surfaces may be fixed in the angled position. The sliding surfaces may be fixed at an angle between 45-60 degrees.The guide device may comprise four sliding surfaces, arranged as a rectangular frame around the specific landing position.

[0183] The sliding surfaces may be configured to be folded to their angled position after the UAV 1 has landed on the landing platform 31.

[0184] The sliding surfaces may be configured to push the UAV 1 into the specific position. By this, the sliding surfaces may correct any minor deviations in landing position of the UAV 1 from the specific position.

[0185] The sliding surfaces may ensure that the UAV 1 is in a correct position after landing, prior to replenishing, to ensure correct connection to the replenishing interface.

[0186] The sliding surfaces may comprise plates, such as sheet metal plates or plastic plates.

[0187] The guide device may, in alternative embodiments, comprise a recess in the landing platform. Such recess may comprise recess walls which form sliding surfaces formed as a cone or funnel towards a specific location of the landing platform.

[0188] The guide device may, in alternative embodiments, comprise juxtaposed tubes, sticks, rods, pipes or poles which may form a fence or grid which may push the UAV 1 , or onto which the UAV 1 may slide, to the specific position.

[0189] The landing platform 31 may be resiliently connected to the frame 32. The resilience may be realized by springs, dampers or elastic material. The resilience may cause a soft landing of the UAV 1 on the landing platform 31.

[0190] The UAV 1 may be steered, or guided, to the specific position by a cone, or funnel, which is conditional on form relative to a product tank 170 of the UAV 1. The product tank 170, which may be downwardly pointy, may be received in the cone or funnel to steer the UAV 1 to the specific position.

[0191] Downwardly pointy members may be provided in corners of a landing platform 113 of the UAV 1 and be received in recesses which are conditional in form relative to the pointy members.

[0192] The frame 32 may comprise one or more support legs (not shown), which may be deployed for stabilizing the airbase 3. Optionally, such supportlegs may be used to provide a predetermined orientation of the airbase 3, e.g. such that the landing platform 31 is oriented horizontally.

[0193] One or more grounding rods (not shown) may be provided on the frame 32, configured for providing grounding of the airbase 3. Such grounding rod may be electrically coupled with the frame 32 and configured to penetrate ground on which the airbase 3 is positioned.

[0194] A grounding rod may be integrated with one or more of the support legs, e.g. such that the grounding rod is made to penetrate ground when the support leg is lowered into contact with the ground.

[0195] In the illustrated example, the landing platform 31 is provided at a vertical level between the lower floor 321 and the upper floor 322. In particular, the landing platform may be situated at a vertical distance from the lower floor 321 which is about 20-80 % of a vertical distance between the lower floor 321 and the upper floor 322, preferably about 30-70 % or about 40-60 %.

[0196] Such a positioning of the landing platform 31 , or landing platforms if several, provides for decreased transport height of the airbase when the UAV(s) 1 are on the airbase 3. The positioning also provides for decreased build height in the event a solid replenishment system, such as the one in figs 5a-5b is to be provided.

[0197] Alternatively, the landing platform 31 may be provided on the upper floor 322, and flush with the upper floor 322.

[0198] Further, in the illustrated example, a tow bar 33 is provided, such that the airbase can be towed by a vehicle, such as a traction vehicle.

[0199] In the illustrated example, the airbase 3 is configured for operation with a farm tractor. However, the airbase may alternatively be configured for operation with a semi-trailer or a swap body type lorry or trailer.

[0200] It is conceivable that the airbase 3 may be provided on vehicle platform, either integrated with a heavy vehicle chassis or as a heavy vehicle trailer. It is also conceivable that the airbase may be provided as an autonomously drivable platform.A ladder 34 may be provided to enable operator access to the upper floor 322.

[0201] A handrail 37 may be provided at any floor where it may be required or desired. The handrail 37 may be foldable, so as to reduce height of the airbase 3 for transport. A gate 371 may be provided at the upper floor 322 to prevent an operator from falling down the ladder, and / or to prevent an operator from entering the second floor 322 when an UAV 1 is on or near the landing platform 31. A position of the gate 371 may be detectable by the ground controller 40, such that the ground controller 40 may allow or deny a UAV 1 to land when the gate is in an open or unlocked position.

[0202] A locking state and / or position of the gate 371 may also be controllable by the ground controller 40, so as to selectively prevent access to the upper floor 322 when an UAV 1 is near or at the landing platform 31.

[0203] Optionally, the handrail 37 and the gate 371 , if any, may be configured also to prevent unauthorized access to all or parts of the airbase 3 and in particular to any upper floor 322.

[0204] At such protected parts of the airbase 3, there may be provided one or more cameras and / or biosensor(s) (motion detectors, etc.), configured to detect unauthorized access. Upon such detection, the ground controller 40 may be configured to indicate unauthorized access, to alert an operator and / or to prevent one or more UAVs 1 from landing at the airbase 3. One or more antennas 41 , e.g. for GNSS and / or communication may be integrated with the handrail 37, so as to be foldable with the handrail 37.

[0205] The mobile airbase 3 may be supported by ground supports 36, in particular wheels or tracks.

[0206] In the illustrated example, the lower floor 321 is configured to house diluent (such as water) in diluent containers 351 , product in product containers 352 and fuel in fuel containers 353.

[0207] The containers, and in particular the product containers, may be positioned on one or more slidable shelves 3211. Such shelves may be slidable in a horizontal direction, in particular laterally or rearwardly relative tothe direction of travel for the airbase 3, such that they can be more easily accessed by an operator.

[0208] Side panels 3231 , 3232, 3233, 3234 may be provided to enclose the lower floor 321 in order to restrict access and to protect items stored on the lower floor from theft, dust, debris, rain or sun.

[0209] The side panels 3231 , 3232, 3233, 3234 may, when folded up, provide a horizontal operator platform for supporting an operator. The horizontal operator platform may be used when performing service to the UAV 1.

[0210] The horizontal operator platform may comprise a ladder 34 and a handrail 37. The ladder 34 and / or the handrail 37 may be foldable between a transport position and a working position. The transition between transport position and working position may be controlled by the ground controller 40 in communication with an actuator, such as a hydraulic or electric actuator.

[0211] The transition may be performed in response to, or prior to, the UAV 1 landing on the landing platform 31.

[0212] The transition may be performed simultaneously as the side panels 3231 , 3232, 3233, 3234 are opened, either by being controlled by an actuator or by a mechanical linkage.

[0213] The side panels 3231 , 3232, 3233, 3234 may be biased by a spring or damper. Such spring or damper may facilitate opening of the side panels 3231 , 3232, 3233, 3234 to form the horizontal operator platform. The spring or damper may decrease the force required to open and / or close the side panels 3231, 3232, 3233, 3234.

[0214] The ladder 34 and / or the handrail 37 may be locked in the working position. The locking may be controlled by the ground controller 40

[0215] The horizontal service platform may be reached, or be a part of, the upper floor 322 of the airbase 3.

[0216] The horizontal operator platform may be a part of the landing platform 31.

[0217] At least some of the side panels may be openable to provide access to the interior of the airbase 3.Alternatively, or additionally, the airbase may comprise a device for swapping and / or recharging batteries for powering the UAV 1.

[0218] The ground controller 40 may be provided on the mobile airbase 3. The ground controller may comprise one or more control units, which control all or some of the functions of the airbase and / or the UAV 1. In some embodiments, the ground controller 40 may be embodied as a single processing device, while in other embodiments, the controller may consist of two or more controllers which control different functions, optionally with coordination therebetween.

[0219] A navigation beacon 181 for providing a local navigation signal to the UAV 1 may also be provided on the mobile airbase 3.

[0220] The airbase 3 may also comprise a power generation system (not shown), which may operate with a fuel-driven generator, a generator that is connectable to a power outlet of the traction vehicle and / or solar panels.

[0221] Alternatively, or additionally, the power generation system may comprise batteries. The power generation system may be used to power the functions of the airbase and optionally to charge batteries of the UAV 1.

[0222] Referring to figs 9a-9b, there is illustrated a cross sectional view of a part of the airbase 3.

[0223] In fig. 9a, a slidable shelf 3211 is in its outer position, providing facilitated access to the product containers 352.

[0224] In fig. 9b, the slidable shelf 3211 is in its inner position, with the product containers in the operating position.

[0225] Figs 9a-9b also schematically illustrate a collection trough 38, which extends below the product containers 352, such that spillage from the product containers can be contained in the collection trough 38 and prevented from contaminating the environment.

[0226] One or more such collection troughs 38 may be provided to collect spillage from, in particular product containers 352 and / or fuel containers 353. The collection trough 38 may also extend below any area where fuel and / or product is being handled, such as below the landing platform(s) 31.A general objective may be to provide a system comprising a mobile airbase 3 and a UAV 1 , which can be operated with a minimum of operator supervision required. Hence, ideally, the system should be able to, once deployed to a site, operate continuously without operator interaction, such that one or more UAVs 1 may take off, distribute product, return for replenishment and then resume distribution without operator interaction.

[0227] Hence, operator supervision can be provided remotely, or by an operator who ambulates between two or more airbases 3.

[0228] To this end, takeoff, landing, replenishment and emergency landing should ideally be handled autonomously. Sensors and procedures may be selected so as to provide independence of daylight, such that the system may be operated around the clock.

[0229] Also, sensors may need to be provided in order to monitor for external interference, such as unauthorized people or animals approaching the airbase 3. In some embodiments, communication may be only between the UAV 1 and the airbase 3, with all control functions being provided at the airbase 3, e.g. through the ground controller 40. In such embodiments, on-site operator control and / or supervision would be necessary.

[0230] In some embodiments, additional communication may be to a central control and / or monitoring site, such as via a direct communication link or via a cloud-based system. In such embodiments, the airbase 3 may operate as a gateway, such that the UAV 1 communicates with the airbase 3 and the airbase 3 forwards communication to / from the UAV 1 from / to a remote control site. In such embodiments, an operator could control and / or monitor several airbase / UAV systems remotely and / or ambulatory.

[0231] In some embodiments, the airbase 3 and the UAV 1 may both communicate with a central control site, such as via a direct communication link or via a cloud-based system. This would also allow an operator to control and / or monitor several airbase / UAV systems remotely and / or ambulatory.

[0232] The communication may utilize cellular and / or satellite-based communication technology. Optionally wlan functionality may be used by the airbase 3, if available where the airbase 3 is stationed.Data processing and / or storage may be provided at the airbase 3, in a remote server and / or control site and or by cloud-based computing / storage.

[0233] Fig. 2a schematically illustrates an area map of a field 2 with a first flight path 20a providing a headland 200 around the field 2 and a second flight path 20b for covering the infield 210. The area map illustrated in fig. 2a may be a preliminary prescription map, provided with consideration of the 2D outline of the field 2 only.

[0234] Fig. 2b schematically illustrates an updated area map of the field 2, wherein a plurality of obstacles, in the form of trees 21 , a power line 22 and a building 23 have been identified, which will provide restrictions on the flight path of the UAV 1. Other obstacles may be areas where it is not desired to deposit the product, such as at open water (lakes, ditches, ponds, puddles, etc.), paved, stony, or otherwise non-cultivable areas.

[0235] Fig. 2c schematically illustrates an updated prescription map of the field 2, with the flight paths 20a’ 20b’ being adjusted to avoid the various obstacles 21 , 22, 23.

[0236] Starting from a map of the field 2, with or without preliminary flight paths 20a, 20b (fig. 2a), a first step for preparing an updated prescription map may be to provide a reconnaissance UAV 1000, or to set the UAV 1 in a reconnaissance mode. Such reconnaissance UAV 1000 may be considerably smaller, more agile and less costly to operate. In particular, the reconnaissance UAV 1000 may be a small electrically powered UAV.

[0237] A reconnaissance flight may be made, during which the UAV 1 , 1000 flies over the area using its sensors to detect obstacles 21 , 22, 23.

[0238] For example, the UAV 1 , 1000 may be caused to fly at a safe altitude over the field, i.e. at an altitude that is well above any obstacles, to detect the obstacles 21 , 22, 23. Such safe altitude may higher than what would be a typical distribution height. For example, the altitude may be on the order of 30-100 m.

[0239] Alternatively, or as a second reconnaissance step, the UAV 1 , 1000 may be caused to fly at approximately the altitude at which distribution of the product would take place, to detect the obstacles 21 , 22, 23.In either case, the UAV 1 , 1000 may be caused to fly according to the preliminary prescription map, such as by following the preliminary flight paths 20a, 20b indicated on the preliminary prescription map.

[0240] Subsequent to the reconnaissance step, the prescription map is updated with the obstacles 21 , 22, 23 (fig. 2b) that were detected during the reconnaissance flight. Additional obstacles may be added, which were not properly identified in the original map, based on the prescription map and / or based on other available maps. Such additional obstacles may be added automatically or manually.

[0241] Once the prescription map is complete with the obstacles, an updated flight path 20a’, 20b’ may be provided. The updated flight path may be a 3D path, indicating obstacles or obstacle zones below, beside and above the flight path 20a’, 20b’, while maximizing coverage of the field 2 and minimizing overlap.

[0242] The prescription map may also contain indications to partially limit the product supply, such as by shutting off one or more product dispensers, and / or by adjusting a product dispensing profile.

[0243] Fig. 3a schematically illustrates a prescription map of a field 2 with flight paths 20a, 20b for providing a headland 200 and an infield 210. Each flight path 20a, 20b may be made up by one or more flight path segments 20a1, 20a2, 20a3, 20a4, 20a5, 20a6; 20b1, 20b2, 20b3, 20b4, 20b5, 20b6, with each flight path segment comprising a starting point, and end point and therebetween a flight path which allows the UAV to maintain a constant velocity. That is, a flight path may need to be divided into several flight segments, wherever it is associated with a turn that cannot be made without reducing the velocity. Since such velocity change would be associated with a disturbance of the distribution rate of the product, the distribution may need to be interrupted. Hence, the flight path segments 20a1 , 20a2, 20a3, 20a4, 20a5, 20a6; 20b1, 20b2, 20b3, 20b4, 20b5, 20b6 may also be defined as portions of the flight path where there is no need to interrupt or modify the rate of distribution of the product.Fig. 3b schematically illustrates a magnified portion of the prescription map of fig. 3a with a pair of waypoints WPS, WPV, illustrating a starting point WPS for a path segment of the flight path segment 20b1 and a velocity check waypoint WPV.

[0244] While the starting point WPS denotes the point at which the spreading should commence for the flight path segment 20b1 , the velocity check waypoint WPV is positioned outside the area to be covered by the flight path segment 20b1. In fact, depending on flight altitude, the spreading may be initiated slightly before the starting point WPS, as there may be some delay before the product emerges.

[0245] The velocity check waypoint WPV is aligned with a direction of flight at the starting point WPS and positioned sufficiently far away from the starting point WPS such that the UAV 1 will be able to line up with the flight path segment 20b1 and then accelerate to the predetermined flight speed by the time it reaches the starting point WPS.

[0246] Hence, a velocity check waypoint WPV may be assigned in connection with the starting point WPS of every flight path segment 20a1 , 20a2, 20a3, 20a4, 20a5, 20a6; 20b1 , 20b2, 20b3, 20b4, 20b5, 20b6 where there is a need to change velocity and / or to interrupt distribution of the product in order to change direction of flight.

[0247] The velocity check waypoint WPV may be positioned such that the UAV 1 may fly continuously through it, without having to stop. Hence, in connection with the velocity check waypoint WPV, the UAV 1 may adjust its course and / or its velocity, so as to make sure it has the correct course and velocity at the starting point WPS. In practice, the velocity check waypoint WPV may be situated some 2-10 m, preferably 3-8 m or 4-6 m, before the starting point WPS.

[0248] Similarly, a retardation waypoint (not shown) may be generated at each endpoint of a flight path segment 20a1 , 20a2, 20a3, 20a4, 20a5, 20a6; 20b1 , 20b2, 20b3, 20b4, 20b5, 20b6. Such a retardation waypoint may cause the UAV 1 to stop distribution of the product and it may trigger a retardationoperation, the abruptness of which may be controlled, e.g. in consideration of the environment with respect to obstacles, or the like.

[0249] Fig. 4 schematically illustrates a scenario in which the distribution flight of the UAV 1 is interrupted due to running out of product and in which the resumption of the distribution flight is made at a different starting point in order to reduce the length of flight with a full payload.

[0250] In fig. 4, the field 2 is illustrated with its prescription map including a first path 20a for the headland 200 and a second flight path 20b for the infield 210.

[0251] In particular, the second flight path 20b has a starting point P1 , from which the UAV 1 proceeds along the flight path 20b, going back and forth over the field 2.

[0252] At the interrupt point P2, the product and / or fuel / battery level in the UAV 1 reaches a criterion triggering a replenishment operation. From the point P2, the UAV 1 will fly the shortest allowed route to the airbase 3. The UAV 1 may fly autonomously to the airbase 3, optionally taking any mapped obstacles into account when planning its route to the airbase 3.

[0253] The flight back to the airbase 3 may be performed “backwards”, such that a turning operation, whereby the UAV 1 would turn around so as to face the direction towards the airbase 3, can be avoided.

[0254] At the airbase 3, the UAV 1 may be replenished by product and / or fuel / electricity.

[0255] When resuming the distribution flight, the UAV 1 may, instead of returning to the point P2 at which the distribution flight was interrupted, instead return to another point P3. Typically, this point P3 would be closer to the airbase 3 than the interrupt point P2, such that the flight with a full payload can be reduced, thereby saving fuel / electricity and time. Upon returning to the point P3, the UAV 1 may proceed with one or more of the flight path segment 20a1, 20a2, 20a3, 20a4, 20a5, 20a6; 20b1, 20b2, 20b3, 20b4, 20b5, 20b6 in a different order and / or in a different direction, such as backwards.

[0256] In a system that it configured to operate autonomously, as described by way of introduction, it is possible to provide two or more prescription maps,for different fields 2, each of which may or may not be updated as described above, to the system of the airbase 3 and one or more UAVs 1 , and to control the UAVs 1 to operate according to the prescription maps in a predetermined sequence. Hence, the system can be used to cover several fields 2 without the need for moving the airbase 3.

[0257] Where the same product is to be distributed to several such fields, the concept of returning to a different point (such as P3) instead of to the interrupt point P2 may be extended to apply to several fields. That is, the distribution may be resumed at a different field from where it was interrupted.

[0258] Figs 5a-5b schematically illustrate a mobile airbase 3 having a displaceable landing platform 31. The mobile airbase 3 illustrated in figs 5a-5b also has a tank 355 for a solid product and a feed device 356 for feeding such solid product to a product tank 170 of the UAV 1. Such feed device 356 may comprise an auger type feeder.

[0259] In figs 5a-5b there is also illustrated a replenishing vehicle 5 having a tipper and an auger feeder for filling the product tank 355.

[0260] The product tank 355 and the feed device 356 may be provided on a single level mobile airbase 3 as illustrated in figs 5a-5b or on a multi-level mobile airbase 3 as illustrated in fig. 1b. In particular, the product tank 355 may be positioned on a lower level of the multi-level mobile airbase with the feed device 356 extending up through an upper level and to the height necessary for docking with the UAV 1.

[0261] Hence, a replenishing operation of the UAV 1 will comprise causing the UAV 1 to return to the mobile airbase 3, with the landing platform 31 in a flight position when the UAV 1 lands thereon. Optionally, the UAV 1 may be secured to the landing platform 31 by a locking mechanism, which, e.g. may engage the landing gear 113 of the UAV 1.

[0262] The UAV 1 may be steered into a specific position of the landing platform 31 by sliding, or skidding, on a guide device (not shown).

[0263] The landing gear 113 may slide on the guide device to steer the UAV 1 into a specific position of the landing platform 31. The specific position may be a position where replenishment is to be performed.Alternatively, the UAV 1 may be pushed to the specific position by upfolding of sliding surfaces from a flat position to an angled position after the UAV 1 has landed on the landing platform 31.

[0264] The UAV 1 may be caused to land with its forward direction facing outwardly of the mobile airbase 3. Hence, when landing on a mobile airbase 3 with the landing platform 31 provided at a rear portion thereof, the UAV 1 would land “backwards”, in the sense that the forward direction of the UAV 1 will face backwards of the mobile airbase 3.

[0265] When the UAV 1 has landed on the landing platform 31 and optionally been pushed or steered by the guide device, and optionally been secured thereto, the landing platform 31 may be shifted horizontally and optionally also vertically, to a replenishing position, such that the UAV 1 is brought into contact with a replenishing interface (not shown), which may comprise an outlet of the feed device 356.

[0266] The replenishing interface may be fixed, such that the UAV 1 is movable into engagement with the replenishing interface.

[0267] Alternatively, the replenishing interface may be movable, in particular horizontally, into engagement with the UAV 1.

[0268] For example, the feed device 356 and optionally also all or part of the product tank 355 may be shifted horizontally into engagement with the UAV 1.

[0269] To this end, the landing platform 31 may be slidably mounted to the frame 32 of the mobile airbase 3. Alternatively, the landing platform 31 may be mounted to the frame 32 by means of a parallel linkage mechanism.

[0270] The landing platform 31 may be rollable on the frame 32. The frame 32 may comprise one or more U-shaped beams into which wheels of the landing platform 31 are configured to roll to allow horizontal movement of the landing platform 31. The wheels may be rotatably connected to an underside of the landing platform 31.

[0271] The length of such U-shaped beam, and thereby the available length of horizontal translation of the landing platform 31, may be 1-4 meters, preferably 1,5-2 meters.The translation of the landing platform 31 provides a landing position and a replenishing position. A UAV 1 may land on the landing platform 31 in landing position, which may provide safe clearance to surrounding parts of the airbase 3. The UAV 1 may be brought to the replenishing position where the replenishing interface is brought into contact with a corresponding interface on the UAV 1.

[0272] The UAV 1 may be steered into a specific position of the landing platform 31 , aided by a guide device, when the landing platform 31 is in the landing position.

[0273] The U-shaped beam may also be V-shaped or square shaped, or comprise any other downwardly tapering receptacle cross section.

[0274] The landing platform 31 may be operably connected to the frame 32 via the one or more U-shaped beams and a translation actuator (not shown). The translation actuator may move, slide or roll, the landing platform 31 relative to the frame.

[0275] The translation actuator may be a linear actuator or a rotary actuator. A rotary actuator may be connected to the landing platform 31 via a belt or a chain drive. The translation actuator may be a hydraulic actuator, an electric actuator or a mechanical actuator, such as a crank or lever.

[0276] The translation of the landing platform 31 caused by the translation actuator may cause the replenishment interface to engage with a corresponding interface of the UAV 1.

[0277] After the UAV 1 has been replenished, the landing platform 31 may return from the replenishing position to the flight position, after which the UAV 1 may take off.

[0278] Fig. 6 illustrates a side view of the UAV 1 in communication with satellites 6 forming part of a global navigation satellite system. To this end, the UAV 1 is equipped with a navigation system 16 including sensors for receiving signals from the satellites 6 and for determining a position of the UAV 1 based on such signals.The UAV further comprises a camera system 19, including a camera that is positioned such that it can be used for precision navigation of the UAV 1 in connection with landing at the mobile airbase 3.

[0279] The camera system 19 may be a camera system configured for acquiring images in the visual spectrum and / or configured for acquiring images in an extended spectrum, such as the infra-red spectrum.

[0280] The mobile airbase 3, which is illustrated in a top view in fig. 6, may be provided with machine readable optical markers 311 in one or more predetermined positions relative to the landing platform 31 , such that the flight control system 14 of the UAV 1 can accurately determine the position and / or orientation of the UAV 1 relative to the landing platform 31 in connection with a landing operation.

[0281] The machine-readable optical markers 311 may be configured for visibility in the visible spectrum. Alternatively, or optionally, they may be configured for visibility in the infra-red spectrum. The optical markers may be provided with surface portions having different reflectivity or different gloss. The optical markers 311 may be illuminated, e.g. by light of a specific wavelength.

[0282] Hence, a landing operation may comprise causing the UAV 1 to navigate from work location, e.g. at a field 2, to the mobile airbase 3 using the signal from the satellites 6 and, when the UAV 1 is sufficiently close to the mobile airbase 3, acquiring images by the camera system 19, identifying the machine readable optical markers 311 and determining the relative position and / or orientation of the UAV 1 and the landing platform 31 based on the machine readable optical markers 311 and using this determination of position and / or orientation to land the UAV 1 on the mobile airbase 3.

[0283] Optionally, the local beacon detector 18 may be used to detect and connect to one or more local beacons 181, which may assist in guiding the UAV 1 towards the mobile airbase 3.

[0284] Fig. 6 also illustrates a safety breaker 41 connected to the ground controller 40. The safety breaker may be positioned sufficiently spaced fromthe landing platform 31 such that an operator positioned at the safety breaker 41 is at a minimum risk of being harmed by the UAV 1.

[0285] For example, with a landing platform 31 at a rear portion of the airbase 3, the safety breaker 41 may be positioned at a front portion, such as at a front wall, a front frame member or even at the towbar 33, of the airbase 3.

[0286] Moreover, with the landing platform 31 at an upper floor 322 of the airbase 32, the safety breaker 41 may be positioned at the lower floor 321.

[0287] For example, the safety breaker 41 may be provided as one or more buttons or levers to be manually operated, such as pressed, pulled or turned by the operator, during a landing sequence and / or a takeoff sequence, to ensure that the operator is not at or near the landing platform 31.

[0288] The ground controller 40 may be configured to allow a UAV 1 to land and / or take off only when the safety breaker 41 is being duly operated.

[0289] In the event the mobile airbase 3 is configured to operate autonomously, in the sense that landing, replenishing and takeoff may take place without any operator being present, a proximity detection system may be provided. For example, one or more biological sensors, such as thermal sensors or motion detectors, may be provided for detecting whether any living creatures are in the immediate vicinity of the mobile airbase 3, with operation of the safety breaker 41 being required only in the event one or more living creatures have been detected within a predetermined time period.

[0290] For example, with a landing platform 31 positioned at a rear portion of the mobile airbase 3, the safety breaker 41 may be positioned at a forwardmost portion of the mobile airbase 3. In addition, with a multi-level mobile airbase 3, the safety breaker 41 may be provided at a lower level while the landing platform is at an upper level. As further options, the safety breaker may be provided as a movable part, which can be placed at a safe distance from the mobile airbase 3, including in a vehicle, and in wired or wireless communication with the ground controller 40.

[0291] Fig. 7 schematically illustrates a side view of a mobile airbase 3 having two landing platforms 31a, 31b, one (31b) at a rear portion of the mobile airbase 3 and one (31a) at a forward portion of the mobile airbase 3. Areplenishing system 35 may be situated between the landing platforms 31a, 31b. The replenishing system 35 may have a replenishing interface which can be used for either landing platform 31a, 31b, or it can have separate replenishing interfaces for each landing platform 31a, 31b.

[0292] As is illustrated, the UAV 1 landing at the rear landing platform 31b may be oriented with its working direction Dw facing backwards and the UAV 1 landing at the front landing platform 31a may be oriented with its working direction Dw facing forwards, as seen relative a forward direction of the mobile airbase 3.

[0293] Fig. 8 schematically illustrates a top view of a mobile airbase 3 with a secondary landing site 3000 arranged in the immediate vicinity of the mobile airbase 3.

[0294] While the mobile airbase 3 may be configured in accordance with what has been described above, the secondary landing site 3000 may be arranged on the ground near the mobile airbase 3. For example, the secondary landing site may be situated 10-200 m from the mobile airbase 3 and preferably within a line of sight. The secondary landing site 3000 may be surrounded by a fence 3001 , which may be of a model that is high and dense enough to prevent any larger living creatures (in particular sheep, cattle, horses or other farm animals, or wild game) from approaching the secondary landing platform 3031. Alternatively, the fence 3001 may be of a model requiring it to be recognized as a safety fence, such as a simple barrier.

[0295] The secondary landing platform 3031 may be provided by one or more boards or panels that may be stored on the mobile airbase 3 during transport, the secondary landing platform 3031 may have a levelling system, which may include actuators or jacks (not shown) that allows the user to render it level, even if the ground is not level.

[0296] Alternatively, the secondary landing platform may be provided as one or more markers that is / are placed directly on the ground.

[0297] The secondary landing site 3000 may comprise one or more machine-readable markers 3311 , similar to those 311 on the mobile airbase 3.The secondary landing site 3000 may comprise one or more local beacons 3181, similar to those 181 on the mobile airbase 3. The local beacons 3181 of the secondary landing site 3000 may be connected by wire or wirelessly to the ground controller 40.

[0298] Further landing sites may be provided according to the principles outlined above. For example, it is conceivable to always provide one excess landing site, such that there will always be more landing sites available than UAVs. It may also be desirable to designate one or more emergency landing sites, which may be sites that are not physically marked as landing sites, but where the UAV 1 could set down with a minimum risk of causing damage or injury.

[0299] For example, the ground controller 40 may be configured to detect a person, animal or object in the immediate vicinity of the airbase 3 and / or of the secondary landing site 3000, and, based on such detection trigger the UAV 1 to set down on an emergency landing site, either immediately or at such time as the UAV 1 would need to return to the airbase 3 for replenishing or when its operation is finished.

[0300] Fig. 10a schematically illustrates a cross sectional view of a landing cradle 311 , which may be applied to the landing platform 31.

[0301] The landing cradle 311 may comprise one or more cradle parts providing a downwardly tapering receptacle cross section, such that the landing gear 113, or skids forming part thereof, of the UAV 1 will be guided towards a predetermined position on the landing platform 31.

[0302] The landing cradle 311 may comprise a latching arrangement 312, 314 for latching the UAV 1 to the landing platform 31, such that it will maintain its position on the landing platform 31 during replenishment and / or transport.

[0303] To this end, the landing cradle may comprise an actuator 313, which may be controlled by the ground controller 40 and a latching member 314, which may be rotatably or slidably connected to the cradle 312, such that it is movable between an open position where the landing gear 113 may engage or disengage the cradle 312, and a closed position, where the landing gear 113, and thus the UAV, is locked to the landing platform 31.The latching arrangement 312, 314 may comprise a belt or chain which may be controlled by the ground controller 40 to sweep around at least a portion of the landing gear 113 and secure the UAV 1 to the landing platform 31.

[0304] The landing cradle 311 may secure the UAV 1 to the landing platform 31. This may be advantageous during heavy wind or during transport.

[0305] Fig. 10b illustrate an alternative embodiment of a latching arrangement 313, 314.

[0306] A position of a first latching member 314a is fixed relative to the landing platform 31.

[0307] A position of a second latching member 314b is movable relative to the landing platform, and especially to the first latching member 314a.

[0308] The first and second latching members 314a, 314b may be movable relative to each other within a horizontal plane.

[0309] A landing gear 113 of a UAV 1 may be received on the landing platform 31 between the latching members 314a, 314b. The latching members 314a, 314b may move towards each other to securely lock the landing gear 113 in place relative to the landing platform.

[0310] The movable latching member 314b may be caused to move by an actuator 313.

[0311] As seen from above, the movement path of the second latching member 314b may be in a straight patch or in a circular path.

[0312] The latching members 314a, 314b may comprise a respective wedge surface 3141a, 3141b. The wedge surface 3141a, 3141 b may bias the landing gear 113 towards the landing platform 31 when the landing gear 113 is held securely between the latching members 314a, 314b.

[0313] The landing platform 31 may comprise one or more weight sensors 315, such as load cells, configured to allow the weight of the UAV 1 to be measured. This may operate as an indication of the presence of the UAV 1 , as well as to ascertain that the UAV 1 is fueled and / or loaded to the extent expected.Hence, the weight sensor(s) 315 may be used to determine the level of fuel and / or product in the tank of the UAV 1 , instead of, or in addition to, any fuel level meter and / or product level meter provided in the UAV 1.

[0314] The landing cradle 311 may also be provided with a ground contact for providing a grounding of the UAV 1 by connecting it to the frame 32 of the airbase 3, which, in turn, may be duly grounded, e.g. as described above.

[0315] Figs 11a-11b schematically illustrate a dual product tank 355 having a pair of compartments 355a, 355b for holding two different solid products. For example, one of the compartments 355a, 355b may hold seeds and the other may hold fertilizer, or they may hold different seed types.

[0316] A single feed device 356 for feeding product to the product tank 170 of the UAV 1 is provided, which is capable of feeding either product, or a mixture thereof.

[0317] Each compartment 355a, 355b is provided, at a bottom portion thereof, with a compartment feeder 3551a, 3551b, here in the form of an auger. The compartment feeders 3551a, 3551b may be individually operable, such that they can be driven individually, e.g. by providing separate drive units, or a common drive unit for driving a common axle, with a respective clutch device for the compartment feeders 3551 a, 3551 b.

[0318] The compartment feeders 3551 a, 3551 b are configured for feeding the product held in the respective compartment 355a, 355b towards the center of the product tank 355, where it can be picked up by the feed device 356.

[0319] It is possible to provide a respective closure 3552a, 3552b, such as a lid or hatch for shutting off the feed device 356 from the respective compartment 3551a, 3551b, so as to prevent unwanted product from being picked up by the feed device 356. The closures 3552a, 3552b may be slidable along the product feeder 356.

[0320] The compartment feeders 3551a, 3551b, the closures 3552a, 3552b and the feed device 356 may be controllable by the ground controller 40.

[0321] When feeding product to the UAV 1, the closures 3552a, 3552b may be operated such that the closure associated with the compartment 355a, 355b from which the product is being fed is closed before the product tank170 is full, such that all of the product that is in the feed device 356 is fed to the product tank 170. Hence, the feed device 356 may be completely emptied of product, such that it is ready for feeding a different product, e.g. from the other compartment 355a, 355b.

[0322] The determination of whether the product tank 170 is nearly full can be made based on the weight of the UAV 1 as determined e.g. by the load cell(s) 315. Alternatively, an internal product tank level sensor in the UAV 1 may be used to detect product level and communicate this to the ground controller 40 that controls the compartment feeders 3551a, 3551b, closures 3552a, 3552b and the feed device 356.

[0323] The present disclosure provides a mobile airbase in the form of a trailer, which includes all functionalities that may be needed for operating an unmanned aerial vehicle in an agricultural setting, such as power generation, handling of chemical product(s), fuel, electronics, communication, lighting, navigation and work space for the operator.

[0324] Referring to figs 12a-12d, there is illustrated a system comprising a replenishment device 3561, 3652 and a product tank 170 for use on a UAV 1, wherein the product tank 170 is partially sectioned.

[0325] This system addresses the challenge of replenishing a product tank that has a limited height, and in particular to do so in a very short time, such as less than about 60 seconds, preferably less than about 30 seconds.

[0326] In the illustrated example, the replenishment device 3561, 3652 comprises an intermediate product tank 3561 and a replenishment feeder 3562, which may be provided in the form of an auger-type conveyor.

[0327] The intermediate product tank 3561 may be configured for receiving product from the product tank 355 via the feed device 356, described with reference to figs 5a-5b and 11 a-11 b.

[0328] The replenishment feeder 3562 may be configured for feeding product from a lower portion of the intermediate product tank 3561 towards the product tank 170.

[0329] The replenishment feeder 3562 may comprise a casing, which may be essentially tubular, and an auger screw, which may comprise a helical blade.The replenishment feeder 3562 may thus be open towards the intermediate product tank 3561 at a proximal portion thereof and have an output opening at a distal portion thereof.

[0330] The replenishment feeder 3562 may comprise a drive unit 3563, which may be an electric, hydraulic or pneumatic motor, which is configured to rotatably drive the auger screw.

[0331] In some embodiments, the replenishment device may comprise two or more replenishment feeder 3562a, 3562b, which may operate in parallel such that each is configured to receive product from the intermediate product tank 3561 and to deliver product at a respective output opening.

[0332] In figs 12a-12d, there is also illustrated a product tank 170, which may be connected to a landing gear 113. The product tank 170 and the landing gear 113 may form a product distribution module that is connectable to a UAV 1.

[0333] The product tank 170 encloses at least one product space 1700 for receiving a product, in particular a solid product, such as a granular or powdery material.

[0334] At an upper portion of the product tank 170, there is provided a product inlet 1702 and at a lower portion of the product tank 170, there is provided a product outlet 1704, that is connectable to the spreader device 171.

[0335] The product tank 170 further comprises at least one input feeder 1701 , which is configured approximately horizontally at the upper portion of the product tank 170 and which has a length, along a rotation axis thereof, extending over at least 1 / 3, preferably at least , at least % or the entire length of the upper portion of the tank body 1705.

[0336] The input feeder 1701 may be formed as a auger-type conveyor, thus comprising an auger screw.

[0337] Such input feeders 1701 may be made with a relatively low weight. Hence, the input feeder 1701 may be used to provide for a suitable distribution of the product when fed to the product tank 170.

[0338] In some embodiments, the input feeder 1701 may extend with its longitudinal axis, which may coincide with an axis of rotation, in the casewhere the input feeder is provided in the form of an auger-type conveyor, approximately along the working direction Dw.

[0339] In some embodiments, the product tank may have at least two input feeders 1701a, 1701b. For example, the input feeders may extend in parallel with each other and optionally approximately in a common plane.

[0340] The plane may be a plane which is approximately horizontal. In particular, the plane may be horizontal + / - about 15 degs, preferably + / - 10 degs, + / - 5 degs or + / - 1 deg.

[0341] Hence, each input feeder 1701a, 1701b may be connectable to a respective replenishment feeder 3562a, 3562b. This connection may be achieved by the horizontal displacement of the UAV 1 towards the replenishment feeder, as described above.

[0342] The input feeder may be freely rotatably arranged relative to the tank body 1705, in particular without any fixedly connected drive unit. Instead, the input feeder 1701 a, 1701 b may be drivable by a torque transferring connection to the replenishment auger 3562a, 3562b. Hence, weight can be saved in the product tank 170.

[0343] The product tank may have a maximum width Wm, a maximum length Lm and a maximum height Hm. The maximum length may be greater than the maximum height.

[0344] In some embodiments, the maximum length may be greater than the maximum width.

[0345] In some embodiments, the maximum width may be greater than maximum height.

[0346] In some embodiments, the product tank 170 may also comprise at least one output feeder 1703, which may be provided at a lower portion of the tank body 1705 and be configured for feeding product from the product space 1700 towards a product outlet 1704.

[0347] In some embodiments, the output feeder 1703 may present a varying displacement along a rotation axis thereof.

[0348] In some embodiments, the output feeder may present at least two output feeder sections, which may be juxtaposed along the rotation axis of theoutput feeder, such that the output feeder sections may be individually controllable. Individual control may be provided by using separate drive devices and / or by using a clutch arrangement.

[0349] The output feeder (s) may further comprise an output feeder cover, which may be varying or variable along the rotation axis. Hence, the output feeder may be operated such that an opening to the auger screw, through which product is input to the auger screw, can be moved along the length of the output auger, such that product can be output from a desired portion of the product tank 170, thus allowing for control of the product tank center of gravity.

[0350] While the examples above refer to feeders in the form of augers, it is conceivable to use other types of conveyors that are suitable for the conveying of bulk material.

Claims

45CLAIMS1. A method of providing a prescription map for distribution of an agricultural product to an area (200, 210) by means of a distribution unmanned aerial vehicle (“distribution UAV”, 1), the method comprising:providing a preliminary map of the area (200, 210);using the preliminary map to define a preliminary path (20a, 20b) for the distribution UAV to fly in order to sufficiently distribute the product over the area (200, 210);operating a reconnaissance UAV (1000) to fly over the area (200, 210) while detecting obstacles (21 , 22, 23); andadapting the preliminary path (20a, 20b) based on the obstacles (21 , 22, 23) so as to provide a prescription path (20a’, 20b’).

2. The method as claimed in claim 1 , wherein the reconnaissance UAV (1000) is another UAV than the distribution UAV.

3. The method as claimed in claim 1 or 2, wherein the reconnaissance UAV (1000) is operated to fly along the preliminary path (20a, 20b).

4. The method as claimed in any one of claims 1-3, wherein the preliminary path (20a, 20b) is a meandering path as seen in a 2D ground plane.

5. The method as claimed in any one of claims 1-4, wherein said detecting obstacles (21 , 22, 23) comprises recording a plurality of obstacles (21 , 22, 23) by 3D position and extent.

6. The method as claimed in any one of claims 1-5, further comprising updating the preliminary map with the obstacles (21, 22, 23), so as to provide the prescription map.

467. The method as claimed in claim 6, wherein said updating the preliminary map comprises providing a 3D map, wherein said obstacles (21, 22, 23) are indicated by 3D position and extent.

8. The method as claimed in claims 6 or 7, wherein said updating the preliminary map comprises adding ground level along the preliminary path.

9. The method as claimed in any one of claims 1-8, wherein said adapting the preliminary path comprises adjusting a lateral and / or vertical position of the preliminary path so as to avoid the obstacles (21, 22, 23).

10. A method of operating a distribution UAV for distribution of an agricultural product to an area (200, 210), the method comprising:providing a prescription map according to the method of any one of the preceding claims, andoperating the distribution UAV (1) to fly according to the prescription path (20a, 20b; 20a’, 20b’) of the prescription map while distributing at least one product.

11. The method as claimed in claim 10, wherein the UAV (1 ) is operated to distribute the at least one product in accordance with the prescription map.

12. A method of operating an unmanned aerial vehicle, “UAV” (1), for distributing an agricultural product to an area (200, 210), the method comprising:receiving a prescription map, indicating a distribution area (200, 210) and at least one distribution path (20a, 20b; 20a’, 20b’) along which said distribution is to take place,47wherein the distribution path (20a, 20b; 20a’, 20b’) comprises at least one distribution path segment (20a1 , 20a2, 20a3, 20a4, 20a5, 20a6, 20b1 , 20b2, 20b3, 20b4, 20b5, 20b6), along which an even distribution groundspeed is desired,said distribution path segment (20a1 , 20a2, 20a3, 20a4, 20a5, 20a6, 20b1, 20b2, 20b3, 20b4, 20b5, 20b6), having a starting point (WPS) and an end point and extending substantially linearly between said starting point and said end point,receiving a position indicating a velocity check waypoint (VPW), which is aligned with the distribution path segment (20a1 , 20a2, 20a3, 20a4, 20a5, 20a6, 20b1, 20b2, 20b3, 20b4, 20b5, 20b6) and positioned a predetermined distance from the starting point,wherein the UAV (1) is operated such that:when the UAV (1) reaches the velocity check waypoint, the UAV (1) is caused to adjust its groundspeed, such that a predetermined distribution groundspeed is achieved at the starting point (WPS), andthe predetermined distribution groundspeed is maintained along the distribution path segment (20a1, 20a2, 20a3, 20a4, 20a5, 20a6, 20b1, 20b2, 20b3, 20b4, 20b5, 20b6).

13. The method as claimed in claim 12, wherein the UAV (1) is operated to start distribution at the starting point (WPS) and / or to cease distribution at the end point and / or to vary the distribution along the distribution path segment (20a1, 20a2, 20a3, 20a4, 20a5, 20a6, 20b1, 20b2, 20b3, 20b4, 20b5, 20b6).

14. The method as claimed in claim 12 or 13, further comprising controlling an output rate of at least one of the distribution units of the UAV (1) in dependence of an actual groundspeed and / or in dependence of the prescription map.

15. A method of operating an unmanned aerial vehicle, “UAV” (1), for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, the method comprising:receiving a prescription map, indicating a distribution area (200, 210) and at least one distribution path (20a, 20b; 20a’, 20b’) along which said distribution is to take place,operating the UAV (1) to fly along the distribution path (20a, 20b; 20a’, 20b’) while distributing the product, andinterrupting the flight at an interrupt point (P2) between a path start and a path finish,operating the UAV (1) to return to an airbase (3), andoperating the UAV (1) to resume the distribution path (20a, 20b; 20a’, 20b’) while distributing the product,characterized byoperating the UAV (1) to proceed from the interrupt point (P2) to the airbase (3) along a first path,operating the UAV (1 ) to proceed from the airbase (3) towards the interrupt point (P2) along a second path, different than the first path, while distributing the product along at least a portion of the second path.

16. The method as claimed in claim 15, wherein the UAV (1) is operated to be oriented in a predetermined working orientation while flying along a working direction (Dw), and wherein the UAV (1) is operated to fly in a reverse orientation while flying along the first path.

17. The method as claimed in claim 15 or 16, wherein the second path comprises a portion of the distribution path (20a, 20b; 20a’, 20b’) that had not been travelled prior to the UAV (1) reaching the interrupt point (P2).

18. A method of operating an unmanned aerial vehicle, “UAV” (1), for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, the method comprising:operating the UAV (1) to land on a landing platform (31) forming part of a mobile airbase (3), andcausing the landing platform (31) with the UAV (1), and a replenishing interface of the airbase (3) to translate at least partially horizontally relative to each other, such that the replenishing interface is brought into contact with a corresponding interface on the UAV (1).

19. The method as claimed in claim 18, further comprising: receiving a prescription map, indicating a deposition area (200, 210) and at least one distribution path (20a, 20b; 20a’, 20b’) along which said distributing is to take place,operating the UAV (1) to fly along the distribution path (20a, 20b; 20a’, 20b’) while distributing the product, andoperating the UAV (1) to return from the distribution path (20a, 20b; 20a’, 20b’) to the airbase (3).

20. The method as claimed in claim 18 or 19, further comprising securing the UAV (1) to the landing platform (31) prior to the translation.

21. The method as claimed in any one of claims 18-20, wherein the replenishing interface comprises at least one fuel delivery channel and at least one product delivery channel.

22. The method as claimed in claim 21 , wherein the product delivery channel comprises an auger type conveyor.

23. The method as claimed in claim 20 or 21 , wherein the product delivery channel comprises hose or tube connectors for transfer of liquid product.

24. The method as claimed in any one of claims 18-23, further comprising weighing of the UAV (1) at landing.

25. The method as claimed in any one of claims 18-24, further comprising weighing of the UAV (1 ) at takeoff.

26. The method as claimed in any one of claims 18-25, wherein the (1) UAV is caused to land with a UAV (1) working direction (Dw) facing outwardly of the airbase (3).

27. The method as claimed in any one of claims 18-26, wherein the UAV (1) is operated to be oriented in a predetermined working orientation while flying along a working direction (Dw), and wherein the UAV (1) is operated to fly in a reverse orientation while returning from the distribution path (20a, 20b; 20a’, 20b’) to an airbase (3).

28. The method as claimed in any one of the claims 18-27 wherein the UAV (1) is operated to land on the landing platform (31) with the landing platform in a landing position, and wherein the at least partially horizontal translation brings the landing platform (31) towards a filling position.

29. The method as claimed in any one of claim 18-28, wherein operating the UAV (1) to land comprises sliding the UAV (1) on a guide device of the landing platform (31) to guide the UAV (1) towards a specific position of the landing platform (31).

30. The method as claim in claim 29, wherein the guide device surrounds a projected size and shape of a landing gear (113) of the UAV (1 ).

31. A mobile airbase (3) for an agricultural unmanned aerial vehicle, “UAV” (1), the airbase comprising:a frame (32),at least one ground support (36), in particular a wheel, rotatably connected to the frame (32),51at least one landing platform (31), configured for receiving the UAV (1), at least one product supply (355, 356), configured for supplying at least one product to be distributed by the UAV (1 ),characterized in thatthe landing platform (31) is horizontally movable relative to the frame (32) between a landing- and takeoff position and a filling position.

32. The airbase as claimed in claim 31 , wherein the landing platform (31) is horizontally slidably connected to the frame.

33. The airbase as claimed in claim 31 , wherein the landing platform (31) is connected to the frame by a parallel linkage connection.

34. The airbase as claimed in claim 31 , wherein the landing platform (31) is horizontally rollable on the frame (32).

35. The airbase as claimed in claim 31 , wherein the landing platform (31) is rotatable in a horizontal plane relative to the frame.

36. The airbase as claimed in any one of claims 31 -35, wherein a replenishing interface comprises at least one fuel delivery channel and at least one product delivery channel.

37. The airbase as claimed in claim 36, wherein the product delivery channel comprises an auger type conveyor.

38. The airbase as claimed in any one of claims 36-37, wherein the replenishment interface is configured to be disconnected from a corresponding interface of the UAV (1) when the landing platform (31) is in the landing- and takeoff position,and to be connected to the corresponding interface of the UAV (1 ) when the landing platform (31) is in the filling position.5239. The airbase as claimed in any one of claims 31-38, wherein the landing platform (31) is positioned at a vertical distance from a lower floor (321 ) of the airbase which is about 20-80 % of a total distance between the lower floor and an upper floor (322) of the airbase (3), preferably about 30-70 % or about 40-60 %.

40. The airbase as claimed in any one of claims 31-39, further comprising at least one collection trough (38), sized and adapted to extend horizontally below at least one zone where a potentially harmful substance, such as fuel or product is being handled.

41. The airbase as claimed in any one of claims 31 -40, further comprising at least one landing cradle (312), configured for receiving the UAV (1) at a predetermined position relative to the landing platform (31).

42. The airbase as claimed in claim 41, wherein the landing cradle (312) comprises a latching device (313, 314) for latching the UAV (1) to the landing platform (31).

43. The airbase as claim in any one of claims 31-42, further comprising side panels 3231 , 3232, 3233, 3234 pivotably moveable between a closed state and an upfolded state,wherein the side panels 3231 , 3232, 3233, 3234 provide a horizontal operator platform for supporting an operator in an upfolded state.

44. A method of landing an unmanned aerial vehicle, “UAV” (1), for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, on a landing platform (31) of a mobile airbase (3), the method comprising:operating the UAV (1) to fly autonomously in accordance with a satellite-based navigation system,53operating the UAV (1 ) to fly to a position of the airbase (3),using a camera (19) on the UAV (1) to receive images representing the airbase (3),identifying at least one machine-readable indicator (311) on the airbase (3), andusing the machine-readable indicator (311) to guide the UAV (1) to the landing platform (31).

45. The method as claimed in claim 44, further comprising using at least one supplementary radio-based navigation beacon (181), located on the mobile airbase (3), to enhance accuracy of the satellite-based navigation system.

46. The method as claimed in claim 44 or 45, further comprising orienting the UAV (1 ) such that a front end of the UAV (1 ) faces rearwardly of the airbase (3).

47. The method as claimed in any one of claims 44-46, wherein operating the UAV (1) to fly autonomously comprises distributing an agricultural product to an area.

48. The method as claimed in claim 47, wherein distributing an agricultural product to an area comprises operating the UAV (1) to fly in straight, non-overlapping paths back-and-forth across the area.

49. The method as claimed in claim 47 or 48, further comprising terminating, or interrupting, the distribution of agricultural product.

50. The method as claimed in any one of claims 44 to 49, further comprising replenishing the UAV (1) with agricultural product and / or fuel while the UAV (1) is on the landing platform (31).5451. A method of operating an unmanned aerial vehicle, “UAV” (1 ), for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, the method comprising:providing a mobile airbase (3) comprising a landing platform (31) configured to receive the UAV (1),providing a ground controller, in communication with the UAV (1), and providing a manually operable safety breaker (41), in communication with the ground controller (40), the safety breaker (41) being located at a position sufficiently spaced from the landing platform (31),wherein the ground controller (40) is configured to communicate with the UAV (1) to prevent the UAV (1) from landing on the landing platform (31) in case the safety breaker (41) is not being operated.

52. The method as claimed in claim 51, wherein the UAV (1) is configured for autonomous landing on the landing platform (31).

53. The method as claimed in claim 51 or 52, wherein the mobile airbase (3) comprises at least one biological sensor, configured for detecting presence of living creatures in the vicinity of the mobile airbase (3), and wherein the method comprises allowing the UAV (1) to land on the landing platform (31 ) without the safety breaker (41 ) being operated only when no movement is detected by the at least one biological sensor.

54. The method as claimed in any one of claims 51-53, wherein the safety breaker (41) is mounted on the mobile airbase (3), either directly or by wire.

55. The method as claimed in any one of claims 51-54, wherein the ground controller and the safety breaker (41) are arranged in different physical components.5556. A mobile airbase (3) for operating an unmanned aerial vehicle, “UAV”, for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, the airbase (3) comprising:a frame (32),at least one ground support (36), in particular a wheel, rotatably connected to the frame,a pair of landing platforms (31a, 31b), each configured for receiving the UAV (1),at least one product supply (351 , 352, 355, 356), configured for supplying at least one product to be distributed by the UAV (1),wherein the airbase (3) presents a generally elongated shape along a travel direction thereof,wherein a first one of the landing platforms (31a) is located at a front portion of the airbase (3), andwherein a second one of the landing platforms (31 b) is located at a rear portion of the airbase (3).

57. The airbase (3) as claimed in claim 56 wherein the product supply (351, 352, 355, 356) is positioned between the landing platforms (31a, 31b), as seen in a longitudinal direction of the airbase (3).

58. The airbase (3) as claimed in claim 56 or 57, wherein at least one of the landing platforms is horizontally movable relative to the frame.

59. The airbase (3) as claimed in any one of claims 56-58, wherein the first one of the landing platforms is situated at a forwardmost part of the frame, optionally with only a tow bar extending forwardly of the first one of the landing platforms.

60. The airbase (3) as claimed in any one of claims 56-59, wherein the second one of the landing platforms is situated at a rearmost part of the frame.5661. The airbase (3) as claimed in any one of claims 56-60, further comprising at least one fuel supply, configured for supplying liquid fuel to the UAV (1).

62. The airbase (3) as claimed in any one of claims 56-61 , wherein the product supply (351 , 352, 355, 356) comprises an auger type conveyor, configured for supplying a granulated solid product.

63. A method of operating a set comprising at least two unmanned aerial vehicles, “UAV” (1), for distributing an agricultural product to an area (200, 210) over which the UAV (1) travels, the method comprising:providing a mobile airbase (3) comprising a primary landing platform configured to receive one of the UAVs (1 );the airbase (3) comprising a ground controller, configured to communicate with a respective flight controller of the UAVs (1 );preparing a secondary landing site, comprising:selecting a secondary landing site in the vicinity of the airbase (3) and at a safe distance from the airbase (3);providing at least one dedicated passive optical marker at the secondary landing site; andoptionally fencing off the secondary landing site;wherein the ground controller determines if a first one of the UAVs (1) is present at the primary landing platform;wherein the ground controller determines if a second one of the UAVs (1) is incoming for landing; andif the primary landing platform is empty of any UAV (1 ), then directing the second one of the UAVs (1) to the primary landing platform; andif the first one of the UAVs (1 ) is present at the primary landing platform, then directing the second one of the UAVs (1) to the secondary landing site.5764. The method as claimed in claim 63, wherein the passive optical marker is detectable by the UAVs (1) to provide landing route guidance.

65. The method as claims in claim 63 or 64, further comprising, if the second one of the UAVs (1) is directed to the secondary landing site, directing the second one of the UAVs (1 ) to the primary landing platform when the first one of the UAVs (1 ) is not present at the primary landing platform.

66. A product supply system (351, 352, 355, 356), comprising: a product tank (351 , 352, 355) having at least two product compartments (355a, 355b), configured for holding a respective solid bulk product,a product feeder (356), configured for feeding the solid bulk product from the product tank (351, 352, 355),characterized bya respective compartment feeder (3551 , 3551 a, 3551 b), configured for feeding the product held in the respective compartment (355a, 355b) towards the product feeder (356),wherein the compartment feeders (3551, 3551a, 3551b) are individually controllable.

67. The system as claimed in claim 66, further comprising at least one closure (3552a, 3552b), configured for selectively preventing product from one of the compartments (355a, 355b) from reaching the product feeder (356).

68. The system as claimed in claim 66 or 67, wherein at least one of the compartment feeders (3551, 3551a, 3551b) comprises an auger.

69. The system as claimed in any one of claims 66-68, wherein the product feeder (356) comprises an auger.5870. The system as claimed in any one of claims 66-69, wherein at least one of the compartment feeders (3551 , 3551 a, 3551 b) is configured for feeding the product in an essentially horizontal direction.

71. The system as claimed in any one of claims 66-70, wherein the product feeder is configured for elevating the product to a higher vertical level.

72. An airbase (3) as claimed in any one of claims 31-43, wherein the product supply is configured as claimed in any one of claims 66-71.

73. A method of operating the product supply system as claimed in any one of claims 66-71 for feeding an agricultural product to an unmanned aerial vehicle, “UAV”, for distributing the product to an area (200, 210) over which the UAV (1) travels, the method comprising:operating the product feeder (356) to feed the product to a product tank of the UAV (1),operating one of the compartment feeders (3551 , 3551 a, 3551 b) to feed the product to the product feeder (356),receiving an indication that a predetermined product level of the product tank (170) has been reached,stopping feeding by said one of the compartment feeders (3551 , 3551a, 3551b), andcontinuing feeding by the product feeder (356) for a time sufficient to empty the product feeder (356) of the product.

74. A method of operating the product supply system as claimed in claim 50 for feeding an agricultural product to an unmanned aerial vehicle, “UAV”, for distributing the product to an area (200, 210) over which the UAV (1) travels, the method comprising:operating the product feeder (356) to feed the product to a product tank of the UAV (1),59operating one of the compartment feeders (3551 , 3551 a, 3551 b) to feed the product to the product feeder (356),receiving an indication that a predetermined product level of the product tank (170) has been reached,operating the closure (3552a, 3552b) to stop feeding to the product feeder (356), andcontinuing feeding by the product feeder (356) for a time sufficient to empty the product feeder (356) of the product.

75. A product tank (170) for use in a UAV, in particular for a solid material, in particular granular or powdery material, comprising:a tank body (1705), which provides an enclosed product space (1700), a product inlet (1702), at an upper portion of the tank body (1705), a product outlet (1704), at a lower portion of the tank body (1705), at least one input feeder (1701, 1701a, 1701b), provided at the upper portion of the tank body (1705) and having a length, along a longitudinal direction thereof, extending over at least 1 / 3, preferably at least , at least % or the entire length of the upper portion of the tank body (1705).

76. The product tank (170) as claimed in claim 75, wherein the input feeder (1701 , 1701 a, 1701 b) extends approximately along a working direction Dw.

77. The product tank (170) as claimed in claim 75 or 76, wherein the product tank (170) has at least two input feeders, preferably extending in parallel with each other and more preferably in the same plane.

78. The product tank as claimed in any one of claims 75-77, wherein the input feeder (1701, 1701a, 1701b) comprises at least one auger-type conveyor.6079. The product tank (170) as claimed in claim 78, wherein the product input feeder (1701, 1701a, 1701 b) is freely rotatably arranged relative to the tank body (1705), in particular without any fixedly connected drive unit.

80. The product tank (170) as claimed in any one of claims 75-79, wherein the product tank (1701, 1701a, 1701b) has a maximum width Wm, a maximum length Lm and a maximum height Hm, with the maximum length being greater than the maximum height.

81. The product tank (170) as claimed in any one of claims 75-80, further comprising at least one output feeder (1703), at the lower portion of the tank body (1705).

82. The product tank as claimed in any one of claims 75-77, wherein the output feeder (1703) comprises at least one auger-type conveyor.

83. The product tank (170) as claimed in claim 82, wherein the output feeder (1703) presents a varying displacement along a rotation axis thereof.

84. The product tank (170) as claimed in claim 82 or 83, wherein the output feeder (1703) presents at least two output auger sections, which are juxtaposed along the rotation axis, wherein the output auger sections are individually controllable.

85. The product tank (170) as claimed in any one of claims 81 -84, further comprising an output feeder cover, which is varying or variable along a rotation axis of the output feeder (1703).

86. A system comprising a replenishment device and the product tank (170) as claimed in any one of claims 75-85,61wherein the replenishment device comprises a replenishment product tank (170) and a replenishment feeder, configured to convey product from the replenishment product tank (355, 3561) to the UAV product tank (170), wherein the replenishment feeder (3562, 3562a, 3562b) comprises a drive unit (3563), andwherein the replenishment feeder (3562, 3562a, 3562b) is connectable to the input feeder (1701 , 1701 a, 1701 b), such that the input auger (1701 , 1701 a, 1701 b) is drivable by the replenishment feeder (3562, 3562a, 3562b).

87. The system as claimed in claim 86, wherein the replenishment product tank (355, 3561) comprises a main product tank (355) and an intermediate product tank (3561 ), with the replenishment feeder (3562, 3562a, 3562b) configured to output product from the intermediate product tank (3561).

88. The system as claimed in claim 86 or 87, when dependent on claim 77, wherein the replenishment device comprises at least two replenishment feeders (3562, 3562a, 3562b), connectable to a respective one of at least two input feeders.

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