Spreader units, methods for spreading agricultural product and unmanned aerial vehicles for spreading agricultural product

Abstract

An unmanned aerial vehicle (1) for spreading an agricultural product to a field (2) comprises a frame (11), one or more rotationally driveable rotors (12) connected to the frame (11), and a spreader unit (10, 20) for spreading agricultural product. The spreader unit (10, 20) comprises a spreader unit support (101, 201) and a spreader section (102, 202). A proximal end (1011) of the spreader unit support (101, 201) is connected at the frame (11) and a distal end (1012) of the spreader unit support (101, 201) extends away from the frame (11). The spreader section (102, 202) is connected at the distal end (1012) of the spreader unit support (101, 201). The distal end (1012) is located outside, as seen in a horizontal direction, a downwash area caused by the rotors (12), in particular during flight in a working direction (Dw). There is disclosed further unmanned aerial vehicles, spreader units and methods of operating such spreader units.

Description

[0001] SPREADER UNITS, METHODS FOR SPREADING AGRICULTURAL PRODUCT AND UNMANNED AERIAL VEHICLES FOR SPREADING AGRICULTURAL PRODUCT

[0002] Technical field

[0003] The present disclosure relates to the field of spreading of agricultural product, more specifically granulated, powdered or liquid product. In particular, the disclosure relates to devices and a method which may be used together with agricultural implements, in particular airborne implement carriers, such as drones. However, some aspects of the present disclosure are applicable also to ground-based spreading devices.

[0004] Background

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

[0006] Different spreading techniques exist for product of the different forms.

[0007] 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.

[0008] A common technique of spreading granulated material is via so called overlapping, which spread product wider than a rated working width of the implement used. A problem with overlapping appears at the borders of the field, where the overlapping may cause product to be spread outside of the field border, or where too little of the product is dispensed.

[0009] A common problem for traditional spreading techniques is the inevitable tramlines needed. Tramlines decrease the arable field area and increase soil compaction locally.

[0010] Moreover, ground-based spreading may be difficult when fields are wet, as machines tend to sink and get stuck.

[0011] 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 spreading implement, in a negative way. Rain may also cause problems, limiting the ability for tractors or other ground-based vehicles to get traction in field.

[0012] Hence, there has arisen an interest in the use of UAVs or "drones" equipped with spreader units for spreading various products.

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

[0014] It is an objective of the present disclosure to provide solutions to the above- mentioned problems. Specific objectives include the desire to achieve more accurate spreading of the agricultural product over the field, and in particular along field borders and irregularities, as well as faster spreading.

[0015] The invention is defined by the appended independent claims. Embodiments are set forth in the appended dependent claims, in the following description and in the attached drawings.

[0016] According to a first aspect, there is provided an unmanned aerial vehicle for spreading an agricultural product to a field. The unmanned aerial vehicle comprises a frame, one or more rotationally driveable rotors connected to the frame, and a spreader unit for spreading agricultural product. The spreader unit comprising a spreader unit support and a spreader section. A proximal end of the spreader unit support is connected at the frame and a distal end of the spreader unit support extends away from the frame. The spreader section is connected at the distal end of the spreader unit support. The distal end is located outside, as seen in a horizontal direction, a downwash area caused by the rotors, in particular during flight in a working direction.

[0017] The unmanned aerial vehicle may in particular be a rotary wing UAV, having at least one rotor.

[0018] The UAV may cause a so-called downwash airstream, or just downwash. Downwash is the airstream created by the one or more rotors to create the lifting force to keep the UAV flying. When tilting the UAV, the downwash is also tilted creating a motion of the UAV. The steeper the tilt of the UAV, the faster the travelling speed of the UAV.

[0019] The downwash area may be defined as an area spanning a volume under the unmanned aerial vehicle, outside of which the spreading pattern of spread product from the unmanned aerial vehicle is essentially unaffected by the air stream from the one or more rotationally driveable rotors.

[0020] The downwash volume, or "column", may have different shapes, such as cylindrically, conically or pyramid shaped.

[0021] Alternatively, the downwash area may be defined as an area spanning a volume under the unmanned aerial vehicle, the area defined as footprint surface provided by an outer perimeter of the unmanned aerial vehicle, including outer perimeter(s) of the rotor(s).

[0022] It is understood that the downwash area referred to is the downwash area as it appears during flight in a forward direction along the working direction.

[0023] The outer perimeter of the UAV may be defined as the outer edges of the one or more rotationally driveable rotors during flight of the UAV.

[0024] The spreader section comprises the device used to dispense the product onto the field. In the present disclosure, examples of spreader sections include rotating discs for spreading a granular or powdery product and a sprayer beam for spreading a liquid product.

[0025] Throughout this specification, "product", both granular, powdered or liquid, may imply seeds, fertilizer, herbicide, pesticide or fungicide. The spreader unit support is a device which connects the spreader section to the UAV. The connection may be direct, e.g. to the frame of the UAV, or indirect, such as to a subframe of the spreader unit or to a product tank of the spreader unit.

[0026] The spreader unit support may comprise a pipe configured to provide agricultural product from a product supply to the spreader unit. The agricultural product may fall by gravity inside a pipe of the spreader unit support. A pipe comprised in the spreader unit support may be conically shaped. A bigger inner diameter of the pipe may face the distal end and a smaller inner diameter may face the proximal end of the spreader unit support. This shape may prevent product from congesting within the pipe.

[0027] By letting the spreader unit be carried by an UAV, tramlines may be avoided leading to increased arable field area. The absence of tramlines may also decrease the soil compaction which may be beneficial for the result of succeeding field operations, such as shallow cultivation.

[0028] Spreading of a product from an UAV may facilitate spreading during weathers that would cause challenges for traditional spreading techniques. Spreading of a product from an UAV may be performed during rainy weather since an UAV may fly equally good when it rains as when it does not. Spreading of a product from an UAV may be performed in more windy conditions than traditional spreading techniques since the UAV may adapt for the windy conditions in a freer way. Traditional spreading techniques are often limited to the tramlines when spreading a product.

[0029] Spreading a product from an UAV may be performed in faster travelling speeds than what is typically known by traditional spreading techniques.

[0030] A prerequisite for efficient spreading of a product is spreading the product from an altitude high enough to allow for the product to be spread the desired distance. A lower spreading altitude will result in a shorter spreading distance.

[0031] It is commonly known that a prerequisite for flying an UAV is to keep the pitch and roll controlled such that the UAV is tilted only towards the working direction. The pitch is commonly used for forward and rearward control and the roll is commonly used for the left and right control. The flight speed of the UAV is commonly controlled by the orientation of the UAV, where a steeper orientation leads to a faster flight speed. With a spreader unit as disclosed above carried by an UAV, accurate and controllable spreading of product can be achieved while maintaining a correct flight orientation of the UAV when travelling over the field.

[0032] The orientation of the UAV, comprising pitch, roll and yaw, may be controlled by changing the angle of one or more rotor blades of the UAV making the UAV tilt in a specific orientation. The orientation of the UAV may also be controlled by controlling different rotors of the UAV to different rotational speeds.

[0033] By supporting the spreader unit at position outside the downwash area, interference from the downwash on the desired spreading pattern from the spreader unit is reduced. Also, a faster travelling speed of the UAV may direct the downwash further away from the spreader unit. The UAV for spreading agricultural product defined above allows for faster travel speed over the field during spreading than what is typically known by traditional spreading techniques. By supporting the spreader unit outside of the downwash area, the UAV defined above reduces the affection from the downwash on a desired spreading pattern.

[0034] The distal end of the spreader unit support may be provided forwardly of the unmanned aerial vehicle, as seen relative to a working direction.

[0035] The working direction is defined as the direction the spreader unit is travelling in during normal use in field. Hence, the working direction would typically be a direction which is parallel with the surface of the field over which the UAV travels.

[0036] When tilting the UAV forwards to achieve forward motion the downwash column may tilt downwardly backwards. With faster forward speed of the UAV, the resulting backwardly tilt of the downwash column may increase since the UAV is constantly moving forwards. By providing the spreader unit in front of the UAV during field work, the affection from the downwash may be further reduced by the forward motion of the UAV.

[0037] According to a second aspect, there is provided an unmanned aerial vehicle for spreading an agricultural product to a field. The unmanned aerial vehicle comprises a frame comprising a landing gear, one or more rotationally driveable rotors connected to the frame, and a spreader unit for spreading agricultural product. The spreader unit comprising a spreader unit support and a spreader section. A proximal end of the spreader unit support is connected at the frame and a distal end of the spreader unit support extends away from the frame. The spreader section is connected at the distal end of the spreader unit support. The distal end of the spreader unit support, during flight, is configured to be located at a vertically lower level than the unmanned aerial vehicle, in particular at a vertically lower level relative to a lowermost portion of the landing gear.

[0038] It is conceivable that the landing gear may be retractable. In such case, the vertically lower level may be lower than a lowermost portion of the UAV frame, or of the thus retracted landing gear.

[0039] In particular, the distal end of the spreader unit support may extend downwardly of a lowermost point of the landing gear, preferably by a distance corresponding to at least 50 % of a landing gear height. Preferably the distal end of the spreader unit support may extend vertically below the lowermost portion of the landing gear by a distance of at least 0.5 m, preferably at least 1 m or at least 2 meters.

[0040] The vertical extension may allow for the UAV to fly at a higher altitude than it would be able to without the vertical extension, with maintained spreading performance. Spreading performance may decrease with altitude since the product is exposed to wind during a longer time. The higher altitude may decrease the risk for the UAV to collide with obstacles, such as humans or wildlife animals and plants.

[0041] The distal end may be located outside, as seen in a horizontal direction, a downwash area caused by the rotors. In particular, the distal end of the spreader unit support may be provided forwardly of the unmanned aerial vehicle, as seen relative to a working direction. The spreader unit support may be rigid between the proximal end and the distal end.

[0042] Throughout his specification, "rigid" is meant without joints.

[0043] The proximal end may be located under a horizontal footprint of a UAV body. A "UAV body" may be the UAV without its rotors, and without any potential protections around the rotors.

[0044] The proximal end may be directly connected to a product tank of the UAV.

[0045] The spreader unit support may present a continuous axial direction from the proximal end to the distal end.

[0046] Hence, when the spreader unit support is in an operating orientation, it will present a continuous and optionally constant downward incline from the proximal end to the distal end.

[0047] The proximal end of the spreader unit support may be pivotably connected to the UAV.

[0048] The pivotal connection may cause the spreader unit support to be pivotable about a pivot axis which is horizontal and transverse a working direction of the UAV.

[0049] The proximal end may comprise one or more axially aligned holes through which a screw, or breaker bolt, may be connected to the UAV. The one or more holes may define a pivot axis of the spreader unit support relative to the frame.

[0050] The connection to the UAV may be to the frame of the UAV or to another item forming part of the UAV, such as a product tank.

[0051] The spreader unit support may be folded to a folded state. In the folded state the lowermost point of the spreader unit support and the spreader unit is above the lowermost point of a landing gear.

[0052] The pivotability may be used for folding of the spreader unit support. The ability to fold the spreader unit support may be used prior to landing of the UAV. The ability to fold may also be used for height adjustment of the spreader unit above crops. A joint in the folding and height adjustment mechanism may be a hinge, or in the form of a hook and pin. The lowermost point of the spreader unit or spreader unit support may be configured to be above a lowermost point of a landing gear in folded mode.

[0053] The spreader unit may comprise a distance sensor and a height adjusting actuator, the distance sensor being configured to measure a height from the spreader unit to a crop and / or ground, and the height adjusting actuator being configured to adjust the spreader unit support so as to keep the height of the spreader unit at a predetermined height above the crop and / or ground.

[0054] The distance sensor may measure a distance to crops and / or the ground. In particular, the distance sensor may be arranged at the distal end of the spreader support, or on the spreader section.

[0055] The distance sensor may be configured to measure the height to the crop in front of the UAV. The height adjusting actuator may comprise a linear or rotary actuator, such as a hydraulic cylinder or an electric motor. The height adjusting actuator may be an actuator which also controls the folding of the spreader unit support prior to landing.

[0056] The height adjusting actuator may cause the spreader unit support to pivot about a pivot point at the proximal end of the spreader unit support.

[0057] The height adjusting actuator may be able to change a height of the spreader unit faster than a change in flight altitude for the UAV may be achievable. The distance sensor and the height adjusting actuator may therefore allow for fast flying speed of the UAV at a predefined altitude while maintaining height controllability to adapt for obstacles and ground contours along the working direction.

[0058] The unmanned aerial vehicle, and / or the spreader unit, may further comprise an anti-collision system comprising at least one collision detection sensor, wherein the collision detection sensor is arranged at the distal end of the spreader unit support, such that the collision detection sensor is located outside, as seen in a horizontal direction, a downwash area caused by the rotors and / or located at a vertically lower level than the unmanned aerial vehicle.

[0059] The collision detecting sensor may be any contactless sensor, such as a radar or a lidar. The anti-collision system may comprise multiple collision detecting sensors. The collision detecting sensor may be connected to the UAV. The collision detecting sensor may also be connected to the spreader unit or the spreader unit support.

[0060] In particular, the distance sensor may be arranged at the distal end of the spreader support, or on the spreader section.

[0061] The collision detecting sensor may transfer information to a processing unit. The processing unit may be a dedicated processing unit. The processing unit may also be a part of a processing unit of the UAV or the spreader unit.

[0062] Hence, the collision detection sensor may be arranged on the spreader unit support itself, or on a section that is mounted on the spreader unit support.

[0063] For example, in the case of a spreader unit comprising a spreader beam, one or more collision detection sensors may be arranged at various positions on the spreader beam.

[0064] The anti-collision system may be configured to modify a flight path of the unmanned aerial vehicle to avoid collision with an obstacle detected by the collision detection sensor.

[0065] The changed flight path of the UAV may in particular be increased altitude, but other measures, such as a sideways movement, a controlled landing or a return to base may also be contemplated.

[0066] The spreader unit support may further comprise a release mechanism, configured to release the spreader unit support from the unmanned aerial vehicle when subjected to a predetermined external force.

[0067] The release mechanism may comprise a hook provided at the proximal end of the spreader unit support, and a pin provided on the frame. The release mechanism may be configured to release the spreader unit support from the unmanned aerial vehicle when acted upon by the predetermined force. The release mechanism may be suitable for action when hitting obstacles of big size or with high force.

[0068] The release mechanism may be provided at the connection between the spreader unit support and the frame. The hook and the pin may provide a pivot point for the spreader unit support.

[0069] The hook may be configured to attach to the pin so that the spreader unit support hangs in the pin. A sufficiently large force may detach the hook from the pin to release the spreader unit support from the frame. The hook may also be provided on the frame and the pin may also be provided on the spreader unit support.

[0070] The release mechanism may comprise a breaker bolt, arranged to break at a predetermined force. The spreader unit support may comprise a hole through which the breaker bolt is arranged. The breaker bolt may be connected to the frame of the unmanned aerial vehicle. The breaker bolt may act as a pivot point of the spreader unit support relative to the frame.

[0071] The unmanned aerial vehicle may provide a user with geographical data regarding where the spreader unit support has been released.

[0072] The spreader unit may be connected to the spreader unit support via a parallelism mechanism, configured to control a pitch of the spreader unit, in particular of the spreader section.

[0073] The parallelism mechanism may comprise a pitch actuator and a pitch sensor.

[0074] The pitch actuator may be configured to control a pitch of the spreader unit.

[0075] The pitch sensor may be configured to provide angle measurements corresponding to a pitch orientation of the spreader unit.

[0076] A controller, which may be a spreader unit controller or a UAV controller may receive the measurements and control the pitch actuator, which is configured to control the pitch of the spreader unit.

[0077] Pitch is a well-known term with obvious meaning for a person skilled in the art.

[0078] By pitch is throughout this specification meant an angle about a laterally extending, generally horizontal, axis.

[0079] The parallelism mechanism may adapt for angle changes between the frame and the spreader unit support. Angle changes may appear as a consequence of height adjustment of the spreader unit by the spreader unit support. The pitch sensor may be a gyroscopic sensor. The pitch actuator may strive to keep the spreader unit parallel to a predefined plane,

[0080] One or more of the one or more rotors may be angled relative to the frame such that the downwash airstream created by the one or more rotationally driveable rotors is angled away from the spreader unit. In particular, the rotors may be angled away as seen in the working direction.

[0081] The tilt of the one or more rotors may be such that rotation axes of at least some of the one or more rotors are parallel with each other and tilted such that the downwash is directed downwardly and backwards. This may apply in particular to front rotors, as seen in the working direction. Alternatively, all rotation axes from the one or more rotors may be tilted, such that downwash will extend downwardly and inwardly under the UAV as to form an inverted conical or pyramid shape.

[0082] The spreader unit may further comprise a roll mechanism, configured to control a roll of the spreader unit, in particular of the spreader section, around an axis parallel to the working direction.

[0083] The roll mechanism may comprise roll sensors configured to provide height measurements corresponding to a roll orientation of the spreader unit. The controller may control the roll actuator to control the roll of the spreader unit, around an axis parallel to the working direction, based on the provided measurements.

[0084] The roll sensors may be provided at outer ends of a lateral extension of the spreader unit. The roll sensors may measure a plurality of distances between different points along the lateral extension of the spreader unit to the crops. The roll sensors may also provide measurements to a height adjusting actuator for adjusting the height above crops of the spreader unit.

[0085] Roll is a well-known term with obvious meaning for a person skilled in the art.

[0086] By roll is throughout this specification meant an angle about a longitudinally extending, generally horizontal, axis.

[0087] The spreader section may comprise a rotatably drivable spreader disc and a product supply, configured to feed product to the spreader disc, whereby the spreader disc is configured to spread the product.

[0088] The agricultural product spread by the spreader unit is preferably granulated or powdered product. The granules of the granulated product may be in different sizes. The same package of granulated product may comprise different size of granules. The smallest granules may be in the form of powder.

[0089] The product supply may be a dispensing outlet, which is configured to dispense the product towards the spreader disc. Optionally, the product supply may be provided with a valve or a metering device for controlling the flow of the product.

[0090] The spreader disc may be a circular plate. The spreader disc may rotate around a center of the spreader disc when driveable by a spreader disc drive unit, such as a rotary actuator. The spreader disc may be configured to hurl agricultural product in a direction extending radially from the center of the spreader disc when rotated by the spreader disc drive unit. The spreader disc may be conically shaped. The spreader disc may be rotatably driveable from a spreader disc drive unit. The spreader disc drive unit may be connected to the spreader disc such that rotation of a spreader disc drive unit axle rotates the spreader disc.

[0091] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise a tilt mechanism connected to the spreader disc and comprising a controllable actuator, wherein the controllable actuator is configured to control a tilt angle of a rotation axis of the spreader disc relative to the product supply, such that a spreading pattern from the spreader unit is controllable to be asymmetric relative to a vertical plane comprising a working direction.

[0092] The spreader unit defined above facilitates accurate spreading of product close to field borders or irregularities. A spreading pattern from a rotating spreader disc is typically decreasing in product density along a radial extension from the spreader disc. This gives a high product density close to the rotating centre of the spreader disc, and a low product density further out from the rotating centre of the spreader disc. By tilting the rotation axis of the spreader disc relative to the product supply the spreading pattern may be adjusted to not spread the product further than to the field border or irregularity. By tilting the rotation axis of the spreader disc, a more consistent product density over the field may be achieved. By tilting the rotation axis of the spreader disc, a more distinct edge of the spreading pattern may be achieved compensating for the typically decreasing spreading pattern along a radial extension of the spreader disc. This facilitates a correct amount of product applied to every single crop.

[0093] With control an angle of the rotation axis of the spreader disc is hereby meant to tilt the spreader disc while keeping the spreader disc in rotational motion. By tilting the rotation axis of the spreader disc relative to the product supply, the product supply may be kept at a constant orientation, preferably approximately horizontal, during field work.

[0094] By product density is hereby meant the amount of product per area. The area may be on the ground or, if the product is spread from the spreader unit but has not yet landed on the ground, a horizontal plane above the ground.

[0095] Examples of field irregularities adjacent to which accurate spreading may be beneficial are stones, trees, ponds or water accumulations, buildings, or local areas with specific needs. Specific needs may comprise adjusted rate of product to increase or hold back potential yield, and also to prevent certain weeds or pesticides.

[0096] The tilt mechanism may further comprise a second controllable actuator configured to control a second angle of the rotation axis of the spreader disc relative to the product supply, such that the spreading pattern from the spreader unit is controllable to be asymmetric relative to a vertical plane perpendicular to the working direction.

[0097] The further possibility to tilt the rotation axis of the spreader disc may further improve the accurate spreading of product close to field borders or irregularities.

[0098] The tilt mechanism comprises a pivot joint configured to allow the spreader disc and a spreader disc drive unit to tilt relative to the product supply.

[0099] The spreader disc and the spreader disc drive unit may be in unchanged positional relation relative to each other during tilting.

[0100] The rotation of the spreader disc may be maintained during tilting. The spreader disc drive unit may be an electrical motor, a hydraulic motor or a mechanical transmission configured to transfer rotational motion from an external rotation device.

[0101] The pivot joint may be arranged to keep a center of a surface of the spreader disc at a fix point in relation to the product supply during tilting. This may enable a desired spreading pattern when tilting the spreader disc. The controllable actuator may be configured such that changing the setting of the controllable actuator tilts the spreader disc and spreader disc drive unit. The setting of the controllable actuator may be set from a user or from a predetermination system. The predetermination system may get input from a mapping service providing information about the field borders and irregularities. The controllable actuator may be attached to the spreader disc drive unit at one end and to a spreader unit frame at another end.

[0102] The tilt mechanism may comprise a coupling allowing an angular offset between the spreader disc rotation axis and a spreader disc drive unit drive axle.

[0103] The coupling may be configured to transfer a rotational motion from the spreader disc drive unit to the spreader disc while maintaining an angular offset between the spreader disc drive unit and the spreader disc.

[0104] The coupling may enable a fix position of the spreader disc drive unit relative to the product supply during tilting of the rotation axis of the spreader disc. The spreader disc may be configured to be in continuous rotation during the tilt.

[0105] The controllable actuator may be configured such that changing the setting of the controllable actuator allows an angular offset between the spreader disc and spreader disc drive unit.

[0106] The spreader disc may comprise one or more radial guides extending along a surface of the spreader disc which faces the product supply, wherein the radial guides are configured to hurl the agricultural product during rotation of the spreader disc.

[0107] The radial guide(s) may improve the spreading distance and spreading accuracy of the spreader unit.

[0108] The radial guide(s) may be provided as plates or beams mounted on the spreader disc surface or as ridges or grooves formed on / in the spreader disc surface.

[0109] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise a product tank, mounted on a frame of the unmanned aerial vehicle and wherein the product supply is configured to control a supply of the product from the product tank to the spreader disc.

[0110] In some embodiments, the product supply may be an integrated part of the product tank. The product tank may comprise an opening and a lid which may be configured to be opened and closed. The opening may be configured for manual or autonomous filling of the product tank.

[0111] The control of supply of product from the product tank to the spreader disc may be through an adjustable valve, such as a damper valve or slidable lid. The opening of the damper valve or slidable lid may correspond to a predetermined rate of product. The control of supply may also be done via a rotating actuator which rotates a cylinder with cavities for dispensing product at a predetermined rate.

[0112] The product tank may be rigidly mounted on the UAV and configured to not be removed. The product tank may also be removably mounted to the UAV and configured to be removed for filling or exchanged. The spreader section may comprise at least one sprayer beam for spreading of a liquid product.

[0113] The sprayer beam may, when in an operating position, present a width which is greater than a width of the UAV frame, preferably greater than a total UAV width including rotors.

[0114] The sprayer beam may have a lateral extension relative to the UAV. The lateral extension may correspond to a working width of the sprayer beam. The sprayer beam may be supported such that it is outside of a downwash area.

[0115] By sprayer beam is hereby meant a laterally extending structure that supports a plurality of nozzles and a distribution system. Liquid product is supplied to the distribution system and distributed out of the nozzles as fine mists. The distribution may be aided by an overpressure created by a pump system.

[0116] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise a pivot connection, connecting a pair of laterally juxtaposed parts of the sprayer beam, such that at least a portion of the sprayer beam is upwardly and / or rearwardly foldable.

[0117] The pivotability may allow a part of the sprayer beam to deflect if hit by an obstacle. The hinge pivotability may also enable the sprayer beam to be held in a horizontal spraying mode independently of the orientation of the spreader unit support. The sprayer beam may be rigidly connected to the spreader unit support and the pivot point may be comprised in the sprayer beam.

[0118] The pivotability may also be used to convert the sprayer beam into a transport position with a reduced width.

[0119] Moreover, the pivotability may be used to provide a sprayer beam which is able to more closely follow the profile of the crop or ground over which the UAV passes.

[0120] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise at least one actuator, which is configured to control the pivot connection, and such that a relative pivot position of the parts of the sprayer beam is controllable.

[0121] Hence, the sprayer beam may be controllable to follow the profile of the crop or ground over which it passes.

[0122] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise at least one sprayer screen extending laterally along and downwardly from the sprayer beam.

[0123] The sprayer screen may extend forwardly of the sprayer beam and / or rearwardly of the sprayer beam.

[0124] The sprayer screen may have a lateral extension corresponding to a lateral extension of the sprayer beam.

[0125] The screening device may be configured to provide a region of air which is less affected by downwash or forward working direction. The screening device may have a vertically downwards extension. The vertically downwards extension may have a length corresponding to a desired height between the sprayer beam and crops during field work.

[0126] The screening device may block any air stream from downwash to reach a mist from the sprayer beam. The screening device may also decrease the affection of air stream on a mist from the sprayer beam created by a forward motion of the UAV. The resulting calm region facilitates a correct dispensing of liquid product from the sprayer beam to the crops. By calm region is hereby meant a region free from noticeable wind.

[0127] The sprayer beam may comprise at least one low dosage product supply system.

[0128] The low dosage product supply system may comprise at least one low dosage product tank configured for storing a low dosage product for target spreading, and at least one low dosage product supply controller configured for controlling a flow of the low dosage product to a product pump or to a nozzle.

[0129] The low dosage product may be a liquid product.

[0130] A low dosage product supply may be a pump or a valve.

[0131] A controller may comprise a processing unit or control circuit.

[0132] The product pump may be a pump configured for distributing a broadcast product.

[0133] The nozzle may be a specific, dedicated nozzle for the low dosage product.

[0134] The nozzle may alternatively, or additionally, be a shared nozzle through which also a broadcast product may be distributed.

[0135] The unmanned aerial vehicle, and in particular the spreader unit, may further comprise at least one navigation sensor, which is arranged at the distal end of the spreader unit support.

[0136] Hence, the navigation sensor(s) may be positioned on or close to the spreader unit, so as to compensate for any offset provided by the spreader unit support relative to the navigation sensor(s) forming part of the UAV.

[0137] The spreader unit support may be hollow and present a cross sectional area which expands towards the distal end. Hence, spreader support may be used as a channel for guiding product, in particular solid product, from the product tank to the spreader section.

[0138] To this end, the spreader unit support may comprise at least one elongate member having a length exceeding at least / z of a maximum footprint diameter of the UAV.

[0139] According to a third aspect, there is provided a spreader unit configured for being carried by an unmanned aerial vehicle for spreading an agricultural product to a field, the unmanned aerial vehicle comprising a frame, one or more rotationally driveable rotors connected to the frame, and a spreader unit for spreading agricultural product. The spreader unit comprises at least one sprayer beam for spreading of a liquid product. A pivot connection connecting a pair of laterally juxtaposed parts of the sprayer beam, such that at least a portion of the sprayer beam is upwardly and / or rearwardly foldable.

[0140] By spreader unit may hereby be meant a sprayer beam. The spreader unit is connected to the frame such that a lateral middle point of the spreader unit is comprised in a vertical plane comprising a working direction and a lateral middle point of the frame. The vertical pivot joints may comprise a spring configured to reposition a spreader unit frame after deflection. The vertical pivot joint may comprise a breaker bolt or screw, configured to break at a predetermined deflection force.

[0141] In particular, the vertical pivot joints may be configured to cause a portion of the spreader unit support to fold rearwardly.

[0142] According to a fourth aspect, there is provided a spreader unit configured for being carried by an unmanned aerial vehicle for spreading an agricultural product to a field, the unmanned aerial vehicle comprising a frame and one or more rotationally driveable rotors connected to the frame, the spreader unit comprising a product tank, a spreader unit support and a spreader section, supported by the spreader unit support. The spreader unit support is configured as an elongate part, having a length sufficient to position the spreader section outside a downwash area of the unmanned aerial vehicle when the spreader unit is mounted to the unmanned aerial vehicle.

[0143] The spreader unit support may be hollow and presents a cross sectional area which expands towards a distal end of the spreader unit support.

[0144] According to a fifth aspect, there is provided an unmanned aerial vehicle comprising a spreader unit for spreading an agricultural product, the spreader unit comprising a product supply configured to feed product to a rotatably driveable spreader disc, wherein the spreader disc is configured to spread the product in a direction outwardly from the spreader disc. A tilt mechanism connected to the spreader disc and comprising a controllable actuator. The controllable actuator is configured to control a tilt angle of a rotation axis of the spreader disc relative to the product supply, such that a spreading pattern from the spreader unit is controllable to be asymmetric relative to a vertical plane comprising a working direction.

[0145] According to a sixth aspect, there is provided a method for spreading an agricultural product over a field, the method comprising causing an unmanned aerial vehicle to fly over the field, causing the unmanned aerial vehicle to spread at least one agricultural product from the unmanned aerial vehicle via a rotating spreader disc, and causing a tilting of a rotation axis of the spreader disc relative to a frame of the unmanned aerial vehicle to cause an asymmetric spreading pattern relative to a vertical plane comprising a working direction.

[0146] The method defined above facilitates accurate spreading of product close to field borders or irregularities.

[0147] According to the method, a longer throw will be provided in one lateral direction relative to the working direction and a shorter, and steeper throw will be provided in the other lateral direction relative to the working direction.

[0148] The method may be applied along a field border or an irregularity of the field, such that a shorter throw is provided in a direction from the unmanned aerial vehicle towards the field border or irregularity.

[0149] The method may be typically beneficial at field borders and edges of irregularities where it is typically hard to spread agricultural product to an even product density with traditional spreading techniques. The method may further comprise, in connection with said tilting, adjusting an rpm with which the spreader disc is caused to rotate.

[0150] The method may further comprise, in connection with said tilting, adjusting an rate with which the agricultural product is fed towards the spreader disc.

[0151] According to a seventh aspect, there is provided a spreader unit for spreading an agricultural product to a field, the spreader unit comprising a rotatably driveable spreader disc, and a product supply, configured to supply the product to an axially exposed face of the spreader disc. At least two force sensors are each configured to measure a radial force vector exerted by the spreader disc, wherein the force sensors are configured to detect force vectors along two different directions in a plane perpendicular to a rotation axis of the spreader disc.

[0152] The product supply may be adjustable along at least one of a radial direction of the spreader disc and a rotation direction of the spreader disc.

[0153] The force sensors may be mounted in parallel with an elastic member.

[0154] The force sensors may be provided between a bearing, which rotationally supports the spreader disc and a subframe, which supports the spreader disc and a drive unit.

[0155] The force sensors may be configured to measure forces along respective directions making an angle of about 45-135 degs relative to each other, preferably 80-120 degs relative to each other.

[0156] According to a eighth aspect, there is provided a method of adjusting a spread pattern of a spreader unit for spreading an agricultural product to a field, wherein the spreader unit comprises a rotatably driveable spreader disc, and a product supply, configured to supply the product to an axially exposed face of the spreader disc, wherein the method comprises: causing the product supply to feed product to the spreader disc while the spreader disc is caused to rotate, measuring at least two radial force vectors exerted by the spreader disc during said feeding and rotation, said radial force vectors being measured along different directions in a plane perpendicular to a rotation axis of the spreader disc, and adjusting the product supply relative to the spreader disc based on said force vectors.

[0157] According to a nineth aspect, there is provided a use of an unmanned aerial vehicle as mentioned above, comprising: flying the unmanned aerial vehicle in a first straight path over a predefined area while distributing agricultural product to the area, turning the unmanned aerial vehicle about 180 degrees, flying the unmanned aerial vehicle in a second straight path, wherein the second straight path is parallel to, and laterally spaced from, the first straight path.

[0158] The use may further comprise alternately flying the unmanned aerial vehicle in multiple straight paths and alternately turning the unmanned aerial vehicle about 180 degrees, to effectively cover the area.

[0159] Each straight path may be parallel with, and laterally spaced from, the previously flown straight path.

[0160] The multiple paths may be non-overlapping. According to a tenth aspect, there is provided a use of an unmanned aerial vehicle as mentioned above, comprising: flying the unmanned aerial vehicle over a predefined area, distributing a first agricultural product configured for broadcasting through a primary product supply system, distributing a low dosage agricultural product configured for target spreading through a low dosage product supply system.

[0161] According to an eleventh aspect, there is provided a method of operating an unmanned aerial vehicle, the unmanned aerial vehicle comprising a frame, one or more rotationally driveable rotors connected to the frame, and a spreader unit for spreading agricultural product, the spreader unit comprising a spreader unit support and a spreader section, wherein a proximal end of the spreader unit support is connected at the frame and a distal end of the spreader unit support extends away from the frame, wherein the spreader section is connected at the distal end of the spreader unit support, and wherein the distal end is located outside, as seen in a horizontal direction, a downwash area caused by the rotors, in particular during flight in a working direction. The method comprises when a field operation is finished, or paused for replenishment of the UAV, raising the spreader unit support from an orientation where it is downwardly inclined from the proximal end towards the distal end to an orientation where it is horizontal or upwardly inclined, prior to a landing operation, and in particular prior to a landing operation on a mobile airbase.

[0162] This is particularly advantageous where the spreader unit support is rigid and long enough to extend outside the downwash area, as it allows for a combination of a low connection point to a product tank while the UAV is still able to land without damaging the spreader section.

[0163] Fig. 1 is a schematic perspective view of an unmanned aerial vehicle, which comprises a spreader unit, flying over a field with crops.

[0164] Fig. 2 is a schematic side view of the unmanned aerial vehicle of fig. 1.

[0165] Fig. 3 is a schematic top view of the unmanned aerial vehicle of fig. 1.

[0166] Fig. 4 is a side view of the distal portion of the spreader unit support of the spreader unit in fig. 1.

[0167] Fig. 5 is a schematic front view of the unmanned aerial vehicle of fig. 1.

[0168] Fig. 6 is a schematic side view of the unmanned aerial vehicle of fig. 1.

[0169] Figs 7a-7b are schematic side views of the unmanned aerial vehicle of fig. 1 in different states.

[0170] Fig. 8 is a side view of the distal portion of the spreader unit support of the spreader unit in fig. 1 with additional functionality illustrated.

[0171] Fig. 9 is a schematic perspective view of an unmanned aerial vehicle, which comprises a different type of spreader unit, flying over a field with crops.

[0172] Fig. 10 is a schematic side view of the unmanned aerial vehicle of fig. 9.

[0173] Fig. 11 is a schematic top view of the unmanned aerial vehicle of fig. 9. Figs 12a-12b are schematic and simplified side views of the distal portion of the spreader unit support of the spreader unit in fig. 9 with additional functionality illustrated.

[0174] Fig. 13 is a front view of the spreader unit in fig. 9 with additional functionality illustrated.

[0175] Fig. 14 is a front view of the spreader unit in fig. 9 with additional functionality illustrated.

[0176] Fig. 15a schematically illustrate a UAV comprising a low dosage product supply system.

[0177] Fig. 15b schematically illustrate an enlarged portion of the supply system in Fig 15a.

[0178] Figs 16a-16b schematically illustrate a spreader disk assembly.

[0179] Fig. 17 schematically illustrates an operation principle of the UAV 1.

[0180] Detailed description

[0181] 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.

[0182] 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.

[0183] 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.

[0184] The disclosure will be directed to an unmanned aerial vehicle 1, hereinafter referred to as a "UAV", with two main embodiments of a spreader unit 10, 20; one for solid product and one for liquid product.

[0185] Fig 1. Schematically illustrates, in a perspective view, a UAV 1, which is fitted with a spreader unit 10, 20 according to various embodiments of the present disclosure.

[0186] A 3D coordinate system is defined with the X direction corresponding to a horizontal working direction Dw, the Y direction corresponding to a horizontal direction perpendicular to the X direction and the Z direction corresponding to the vertical direction.

[0187] The UAV 1 comprises a frame 11, one or more rotors 12 and a landing gear 15. Furthermore, the UAV may comprise a controller 16, which may be configured to control the rotors 12 so as to cause the UAV 1 to perform flight operations in accordance with user instructions, which may be provided continuously, e.g. by remote control, or by a predetermined flight plan.

[0188] The controller 16 may also be configured to provide certain flight operations more or less autonomously, such as handling obstacles, collisions, errors or interference. The controller 16 may also be configured to control various functions of the spreader unit 10, 20. For this purpose, the controller 16 may be configured to store and execute software for controlling the spreader unit. This may be advantageous as a common user interface may be used for both flight control and control of the spreader unit 10, 20.

[0189] Alternatively, the spreader unit 10, 20 may comprise its own controller 16, for controlling the functions of the spreader unit 10, 20, optionally including a separate communication device for communicating with an operator.

[0190] The controller 16 may form part of a collision detection system, including one or more collision detection sensors.

[0191] As most UAV platforms can be expected to include one or more collision detection sensors 10214, 20214, no further description is necessary of the parts of the collision detection system that is provided by the UAV platform as such.

[0192] The spreader unit 10, 20 may include one or more collision detection sensors 10214, 20214. In particular, such collision detection sensors 10214, 20214 may be positioned on the parts of the spreader unit 10, 20 which are most likely to collide with obstacles.

[0193] The collision detection system may be configured to respond to the detection of collisions by the collision detection sensors 10214, 20214 in various ways depending, e.g. on the situation in which the detection occurs and / or depending on a direction of a collision force.

[0194] It is contemplated that the collision detection system may respond to some collisions by a manoeuvring the UAV 1. For example, the flight of the UAV 1 may be stopped; the UAV 1 may be caused to tilt backward, to rise or even to return to base.

[0195] However, the collision detection system may respond to some collisions by releasing (e.g. shedding) all or part(s) of the spreader unit 10, 20, as will be described below.

[0196] The collision detection system may also respond to some collisions by allowing a controlled deflection of all or part(s) of the spreader unit 10, 20.

[0197] The collision detection system may be supplemented by mechanical features allowing for deflection (bending, pivoting, release) of all or parts of the spreader unit 10, 20 in response to a collision.

[0198] Also connected to the controller 16, there may be provided one or more navigation sensors 10215, 20215, such as sensors for determining the position of the spreader unit 10, 20 based on any known navigation system, including, but not limited to GNSS, GPS, GLONASS, Galileo, BeiDou, QZSS and / or IRNSS / NavIC. It is also possible to use local / regional navigation systems, e.g. making use of local beacons.

[0199] The frame 11 may be formed in any way deemed suitable. In the illustrated nonlimiting example, the frame 11 is formed according to a general "H configuration", with a web 111 and a pair of flanges 112a, 112b (fig. 3).

[0200] The web 111 may be configured for carrying a load, such as a product tank 14 and a spreader unit 10, 20. Also, the controller 16, and drive unit 17 may be positioned on or in the web. The drive unit 17 may comprise an internal combustion engine, which may drive the various rotors 12 through a transmission. Alternatively, the drive unit may comprise one or more electric motors, which may be centrally located, or located one at each rotor 12.

[0201] The number of rotors 12 may vary from 1 and up. For example, known UAVs are frequently equipped with an even number of rotors, such as, but not limited to, 4, 6, 8 or 10, which are arranged at the corners of a polygon.

[0202] In the illustrated example, the UAV 1 has four rotors 12 positioned at the distal portions of the flanges 112a, 112b.

[0203] As can best be seen in fig. 2, the rotation axes Rr of some or all of the rotors 12 may be slightly inclined, such that the downwash area diminishes in a downward direction from the UAV 1. In particular, rotors 12 positioned at what is the front of the UAV 1, as seen in the working direction Dw, may be thus inclined so as to reduce downwash effect in front of the UAV 1.

[0204] Expressed differently, at least one pair of rotor axes Rr may converge in the downward direction.

[0205] For example, at least one pair of rotors, comprising a front rotor and a rear rotor, may present mutually downwardly converging axes of Rr rotation.

[0206] In some embodiments, rotation axes of both the front and rear rotors of such pair will be inclined relative to the vertical direction.

[0207] In other embodiments, a rotation axis of a front rotor may be inclined relative to the vertical direction while a rotation axis of the rear rotor may be essentially vertical.

[0208] The rotor axes Rr may be inclined outwardly / upwardly by about 1-20 degs from a vertical axis, preferably about 5-20 degs or about 10-15 degs.

[0209] While the above orientations of the rotor axes Rr may be advantageous, the concepts disclosed herein may be used also with other rotor axis orientations.

[0210] When used in agriculture, the UAV 1 may be expected to move in a generally horizontal working direction Dw over a field 2 to which a product is to be distributed. The field 2 may be delimited by field edges 21a, 21b, which may be straight or curved.

[0211] The movement may be in accordance with a pre-programmed flight plan, requiring the UAV 1 to fly on a predetermined height above ground or above a crop 22 and along a preprogrammed path.

[0212] The illustrated UAV 1 further comprises a landing gear 15, which may comprise one or more landing feet, skids, wheels or other structure designed to support the UAV 1 when not airborne.

[0213] The landing gear 15 may be a fixed landing gear, which may have skids, as illustrated. Alternatively, the landing gear may be wholly or partially retractable, e.g. to reduce drag. The landing gear may be fitted with a suspension system for reducing impacts in connection with landing.

[0214] The UAV 1 further comprises a spreader unit 10, 20, which is supported by the UAV 1, and in particular by the frame 11 of the UAV 1. The spreader unit 10, 20 comprises a spreader section 102, 202, which is supported by a spreader unit support 101, 201. The spreader unit support 101, 201 may be formed as one or more elongate parts, which extend between a proximal part 1011, 2011, at which the spreader unit support 101 is mounted to the UAV 1 and a distal part 1012, 2012, which may extend laterally outwardly and / or vertically downwardly from the UAV 1.

[0215] The spreader unit support 101, 201 may be rigid between the proximal part 1011, 2011 and the distal part 1012, 2012.

[0216] The spreader unit support 101, 201 may be rigid between a pivot connection to the UAV 1 at the proximal part 1011, 2011 and a connection point to the spreader section 102 at the distal part 1012, 2012.

[0217] The spreader unit 10, 20 is configured for distributing a product from the product tank 14 to the field 2 as the UAV 1 travels over the field 2.

[0218] To this end, the spreader unit support 101, 201 may be configured as one or more elongate hollow members functioning as both a structural support and as a channel for conveying the product from the product tank 14 to the spreader section 102, 202.

[0219] Alternatively, the spreader unit support 101, 201 may be configured as a hollow or solid member which supports the spreader section 102, 202 and a channel, e.g. in the form of a pipe or tube, connecting the product tank 14 to the spreader section 102, 202.

[0220] Advantageously, an interior of such hollow member, or channel, may present a cross section which expands in the direction from the proximal portion 1011, 2011 towards the distal portion 1012, 2012.

[0221] Feeding of material through such material channel, either arranged inside the spreading unit support 101, 201 or connected thereto, may be aided by airflow.

[0222] Such airflow may be generated at the UAV 1 and may push, or feed, material in the material channel.

[0223] The airflow may be generated by an airflow supplier arranged on the UAV 1 or on a UAV implement. The airflow supplier may be controlled by a controller to be activated during dispense of the product.

[0224] The airflow supplier may be a fan or a pressurized tank, out from which air is controllably released to cause an airflow.

[0225] One or more collision detection sensors 10214, 20214 may be positioned at the distal portion 1012, 2012 of the spreader unit support 101, 201.

[0226] In particular, in some embodiments, one or more collision detection sensors 10214, 20214 may be positioned at laterally outermost portions of the spreader section 102, 202.

[0227] In some embodiments, one or more collision detection sensors 10214, 20214 may be positioned at various points along the width of the spreader section 102, 202.

[0228] One or more navigation sensors 10215, 20215 may be positioned at the distal portion 1012, 2012 of the spreader unit support 101, 201.

[0229] In particular, in some embodiments, one or more navigation sensors 10215, 20215 may be positioned at laterally outermost portions of the spreader section 102, 202.

[0230] In some embodiments, one or more navigation sensors 10215, 20215 may be positioned at various points along the width of the spreader section 102, 202. In some embodiments, the product tank 14 may be fixedly mounted on the UAV 1 and configured to not be removed.

[0231] In other embodiments, the product tank 14 may be removably mounted to the UAV and configured to be removed for filling or exchange.

[0232] A flow control 141, such as a product meter or a valve, as deemed suitable with respect to the type of product to be dispensed, may be arranged at the product tank 14, such as at a lower portion of the product tank 14, for controlling a flow of the product from the product tank to the spreader unit 10, 20.

[0233] The flow control 141 may be provided as an adjustable valve, e.g. a damper valve or a knife valve. The degree of opening of the flow control 141 may correspond to a predetermined rate of product. The control of supply may also be done via a rotating actuator which rotates a cylinder with cavities, or an auger, for dispensing product at a predetermined rate.

[0234] The product tank 14 may be provided with a filling opening 142, in particular at an upper portion of the product tank 14.

[0235] According to the embodiments illustrated with reference to figs 1-8, the product may be a solid product, in particular a granular or powdery product, such as fertilizer and / or pesticide and / or herbicide and / or minerals and / or chalk. It is also possible to distribute seeds.

[0236] According to the embodiments illustrated with reference to figs 9-14, the product may be a liquid product, such as fertilizer and / or pesticide and / or herbicide and / or minerals or chalk in liquid solution.

[0237] In the embodiments of figs 1-8, the spreader section 102 may comprise a product supply 1021 and a spreader disc 1022. With the product supply 1021 being configured to controllably supply the product from the product tank to the field 2.

[0238] Fig. 2 illustrates the UAV 1 during flight along a working direction, as seen in a plane Pw (see fig. 3) comprising the working direction Dw. Fig. 2 also illustrates a vertical plane Pt, which is perpendicular to the working direction.

[0239] Dashed lines 115 indicate an approximate extent of a downwash area provided when by the rotors 12 when the UAV 1 is flying in the working direction Dw.

[0240] Fig. 2 illustrates how the elongate spreader unit support 101 extends from its proximal end 1011 at the UAV 1, such that its distal end 1012 is outside the downwash area 115, such that the effect of the downwash on the product to be distributed to the field 2 is reduced.

[0241] The spreader unit support 101 may extend laterally outside a body of the UAV 1 by a distance corresponding to at least about 10 %, preferably, about 25 %, about 35 %, about 50 % or about 75 %, of a UAV 1 body length along a direction whose projection on a horizontal plane is parallel with the spreader unit support 101.

[0242] The spreader section 102 may be situated entirely outside the downwash area 115. The spreader unit support 101 may extend downwardly of a body of the UAV 1 by a distance corresponding to less than about 300 %, preferably less than about 200 % or less than about 100 %, of a UAV 1 body height along a vertical direction.

[0243] Fig. 3 illustrates the UAV 1 as seen from above. The dashed lines 115, 115' indicate the approximate area, or footprint, of the downwash immediately at the vertical level of the rotors 12 (line 115) and at a vertical level of the spreader unit 10 (line 115').

[0244] Fig. 4 schematically illustrates a spreader section 102 of a spreader unit 10 configured for spreading a solid product towards ground and / or towards a crop 22.

[0245] The spreader section 102 comprises a product supply 1021, a spreader disc 1022, a drive motor 1023 and a drive axle 1024 connecting the drive motor 1023 to the spreader disc 1022.

[0246] The product supply 1021 may, in its most basic form, comprise a channel outlet through which the product is fed, directly, or indirectly, such as through a spreader unit support 101, from a product tank 14. In more advanced versions, the product supply 1021 may comprise a flow control, such as a valve (not shown) or a metering device (not shown), such as an auger or a metering wheel, the rate of which may be controlled to provide a desired product supply rate.

[0247] The product supply 1021 outlet towards the spreader disc 1022 may be adjustable, such that the radial position relative to the spreader disc 1022 of the feed of product can be modified.

[0248] The spreader disc 1022 comprises a generally horizontally oriented rotatably supported disc member 10221, having a generally upwardly oriented surface onto which the product is received from the product supply 1021.

[0249] The spreader disc 1022 may comprise one or more radially extending product guides 10222. Such product guides may be provided by generally radially extending ridges, valleys, paddles or vanes, which guide the product received on the upwardly oriented surface of the disc member 10221 radially outwardly, so as to provide the product with a radial velocity, which will cause the product to be thrown off the spreader disc 1022.

[0250] The drive motor 1023, which may be an electric motor, a pneumatic motor or a hydraulic motor, causes the spreader disc 1022 to rotate about a generally vertical spreader disc rotation axis Rd.

[0251] A tilt mechanism is provided for causing the spreader disc rotation axis Rd to tilt from its vertical orientation. The tilting may be on the order of 0-20 degs. In particular, the tilting may be about -10 - +20 degs.

[0252] The tilt mechanism 1026 may be configured for causing the spreader disc rotation axis Rd to tilt about a first tilt axis Al, which may be approximately horizontal and parallel with the working direction Dw.

[0253] The tilt mechanism may be further configured for causing the spreader disc rotation axis Rd to tilt also about a second tilt axis (not shown), which may be approximately horizontal and perpendicular to the working direction Dw. The tilting may be on the order of 0-20 degs. In particular, the tilting may be about -10 - +20 degs. In connection with the tilting, it may be desirable to also adjust an rpm with which the spreader disc 1022 is caused to rotate.

[0254] Also, in connection with the tilting, it may be desirable to also adjust a feed rate provided by the product supply 1021.

[0255] Consequently, for a given altitude and a given product, adjustment of the spread pattern by tilting the spreader disc may be associated with an adjustment of the rpm and / or of the feed rate.

[0256] It is contemplated that the spread pattern will also be dependent on altitude, product properties.

[0257] Hence, starting from a given altitude, a given product and a given distance to a field border, settings will need to be provided for the tilt angle, the rpm and the feed rate.

[0258] Such settings may be derived by empirical testing, aiming at providing a lookup table providing relations between the variables. Based on such a lookup table, some interpolation and / or extrapolation may be made to derive variables which match the current situation.

[0259] The spreader section 102 may comprise one, two or more spreader disc arrangements 1021, 1022, 1023, 1024 as described above, each of which may be configured to service a particular lateral portion of a working width of the spreader section 102.

[0260] Fig. 5 illustrates the UAV 1 during flight as seen in a vertical plane Pt (see fig. 2), which is perpendicular to the working direction Dw. Fig. 5 also illustrates the vertical plane Pw, which comprises the working direction.

[0261] In particular, fig. 5 illustrates the symmetric spreading pattern Ps provided with the spreader discs 1022a, 1022b in the neutral position (typically with the rotation axis of the spreader discs oriented vertically), as seen in the plane Pt.

[0262] Fig. 5 also illustrates the asymmetric spreading pattern Ps' provided with the spreader discs in a tilted position (i.e. with their rotation axes tilted relative to the vertical direction), as seen in the plane Pt.

[0263] Fig. 6 is a side view of the UAV 1 with the spreader unit 10 adapted for dispensing a solid product onto a crop 22.

[0264] The spreader unit support 101, and in particular its proximal portion 1011, may be connected to the UAV 1 by means of a pivot connection 104 which allows the spreader unit support 101 to pivot relative to the UAV 1 about an axis which is horizontal and perpendicular to the working direction Dw.

[0265] Optionally, the pivot connection 104 may also allow pivoting about an axis which is substantially parallel with the working direction Dw.

[0266] The pivot connection 104 may include a flexible connection for the product, connecting the product tank 14, or the flow control 141, to the spreader unit 10.

[0267] Such a pivot connection 104 may be used to allow for height adjustment of the spreader section 102 relative to the UAV 1.

[0268] Moreover, the pivot connection 104 may be used to allow for the spreader section to be retracted to a level above a lowermost portion of the landing gear 15, such that the UAV 1 may land without being impaired by, or damaging, the spreader unit 10. Referring to fig. 6, there is illustrated a height adjusting arrangement 103, which, in this example, comprises a reel 1031 or winch located on the UAV 1, forwardly of the proximal portion 1011 of the spreader unit support 101, and a wire 1032 or band connected to the spreader unit support 201 and configured to be wound onto the reel 1031. Hence, by controlling the rotation of the reel 1031, a free length of the wire 1032 can be controlled and thus a height position of the distal end 1012 of the spreader unit support 101.

[0269] The reel 16 may also be controlled by the controller 16.

[0270] Other types of height adjustment arrangements are conceivable. For example, a linear actuator (electric, hydraulic, pneumatic) may be configured to operate between the spreader unit support 101 and the UAV frame 111.

[0271] Referring to fig. 7b, the spreader unit 10 may be disconnectable from the UAV 1.

[0272] In particular, the spreader unit 10 may be disconnectable in response to an excessive force being exerted on the spreader unit 10, as may be the case where the spreader unit 10 collides with a non-yielding obstacle, as will be described with respect to fig. 8 below.

[0273] The spreader unit 10 may be disconnectable from the UAV 1 in response to the detection of certain events, such as a collision.

[0274] The disconnection may be achievable entirely mechanically, as a consequence of the force provided by the collision.

[0275] In the following, some non-limiting examples of how to provide such a coupling are outlined.

[0276] A separation assembly may comprise a first component; a second component; and a shear pin oriented transverse to a shear plane, the shear pin configured to fail at a predetermined load such that the first and second components disengage without exceeding a predefined stress in either component.

[0277] The shear pin may include a necked section that defines a failure threshold within ±10% tolerance.

[0278] A separable joint may comprising a frangible segment integrally formed with a bracket, the frangible segment having a stress concentrator aligned with a principal load direction to produce a controlled fracture surface upon impact loading.

[0279] A coupling system may comprise a magnet array disposed to transmit torque across a non-contact gap, the magnets sized to release when torque exceeds a calibrated limit, thereby limiting peak stress in the shafts.

[0280] A reversible fastener system may include a quick-release pin with a spring-loaded detent, the pin dimensioned to maintain engagement under normal operating vibration and to disengage upon manual actuation without tool damage.

[0281] A snap-fit latch may comprise a polymer cantilever tab configured for elastic deflection during assembly and disassembly, wherein maximum strain remains below the material's yield to enable repeated cycles of separation.

[0282] A torque-limiting coupling may include a ball-detent mechanism biased by a spring, the detent configured to disengage at a specified torque and to re-engage upon torque reduction, thereby providing non-destructive overload protection. As yet another option, a hook may be provided with a spring-loaded gate, where the spring is configured to open upon being subjected to a sufficiently high force, and / or where the hook, or a part thereof, is configured to flex upon being subjected to a sufficiently high force, such that the connection is opened and the spreader support 101, 201 is allowed to disconnect.

[0283] In any event, channel openings at the product tank and / or at the spreader support may be provided with a protective lid, which may snap closed to prevent product leakage and / or ingress of debris / soil.

[0284] Alternatively, the disconnection may be triggered based on data from a collision detection sensor, whereby one or more disconnect actuators may be operated to provide the disconnect.

[0285] The spreader section 102 may be provided with a collision detection sensor, such as an accelerometer and / or gyro sensor, which can be used to detect sudden impacts and / or unexpected differences in movement between the spreader section 102 and the UAV 1.

[0286] The controller 16 may be configured to react in various ways to the detection of a collision. For example, the UAV 1 may be caused to immediately halt its movement, to climb, to return to base, to immediately land in a controlled manner and / or to send certain data to an operator. Such data may include images or video sequences, position data or other status data of the UAV 1 within a predetermined period before, and / or after the detection of the collision.

[0287] Disconnection may be associated with an immediate cessation of any feed of material to the spreader unit 10.

[0288] Disconnection may be associated with an immediate halt of the operation of the spreader unit 10.

[0289] Upon disconnection, product connectors may be caused to automatically and mechanically close, such that no, or only a minimum of, product will be unintentionally dispensed.

[0290] Fig. 8 schematically illustrates a spreader section 102 provided with a distance sensor 1025, configured to detect a distance to ground or to a crop 22.

[0291] Referring to fig. 8, at least the active part of the distance sensor 1025 may be supported by the spreader section 102, such that it detects the actual distance from the spreader section 102, preferably a lowermost portion of the spreader section 102, and the ground or the crops 22.

[0292] The distance sensor 1025 may be connected to the controller 16, such that the flight control and / or the control of the height of the distal portion 1012 can be performed with due regard to a signal from the distance sensor 1025.

[0293] For example, it may be desirable to maintain a height of about 30-50 cm above the crop 22.

[0294] The distance sensor 1025 may use any appropriate technology, including ultrasound, infrared, radar, laser, camera and / or LIDAR based technology. Mechanical sensing is also possible, e.g. by providing a device which touches the upper portion of the crop or the ground surface.

[0295] The disclosure of figs 6, 7a-7b and 8 is equally applicable to all embodiments of the present disclosure.

[0296] A second embodiment of the UAV 1 will be described with reference to figs 9-15b.

[0297] The UAV of the second embodiment corresponds to the UAV 1 of the first embodiment, except that its spreader unit 20 is adapted for dispensing a liquid to the field 2.

[0298] To this end, the spreader unit 20 comprises a spreader unit support 201 and a spreader section 202, which takes the form of a sprayer beam 2021 with a plurality of nozzles 2022.

[0299] The spreader unit support 201 is connected, at its proximal end 2011, to the UAV 1 in order to provide for a connection to the product tank 14. Optionally, a flow control 141, such as a valve may be provided for controlling the flow of product from the product tank 14 to the spreader unit 20.

[0300] The spreader unit support 201 is connected at its distal end 2012 to the spreader section 202.

[0301] The distal end 2012 may be located laterally outside the downwash area provided by the rotors 12. Preferably, the distal end 2012 is located laterally outside of the downwash area and forwardly of the UAV 1, as seen in the working direction Dw.

[0302] The distal end 2012 may also be located below a lowermost portion of the UAV 1. In particular, the distal end 2012 may be located below a lowermost portion of the landing gear 15.

[0303] Specifically, the distal end 2012 may be located at least about 0.5 m below the lowermost portion of the landing gear 15, preferably at least about 1, at least about 1.5 m or at least about 2 m.

[0304] The spreader unit support 201 may be formed as a hollow pipe, such that it may function both as a structural support and as a channel for conducting the liquid from the product tank 14 to the sprayer beam 2021.

[0305] Alternatively, the spreader unit support 201 may be formed as a beam (whether hollow or not) which may support one or more liquid channels. Such liquid channels may be provided in the form of tubes or hoses.

[0306] The spreader section 202 may be formed as a hollow pipe, such that may function both as a structural support and as a channel for conducting the liquid to the nozzles 2022.

[0307] The spreader section 202 may be slightly downwardly suspended from the distal portion 2012 of the spreader unit support 201, as illustrated in fig. 9. To this end, a vertical spacer element may be connected between the distal portion 2012 of the spreader unit support 201 and the spreader section 202.

[0308] The spreader section 202 may be pivotably connected to the spreader unit support 201, such that the spreader section 202 may pivot relative to the spreader unit support 201 about a pivot axis A2 that is horizontal and perpendicular to the working direction Dw. The spreader section 202 may be idly pivotable about the pivot axis A2, or it may be controllable by means of an actuator (not shown) connected to the controller 16.

[0309] One or more pitch sensors (not shown) may be provided for determining the orientation of the spreader section 202, such that the controller 16 may control the actuator to maintain a predetermined orientation about the axis A2.

[0310] It is also possible to provide one or more roll sensors (not shown) and a roll actuator (not shown), which may be configured to detect and control a roll position of the spreader section 202, so as to enable the spreader section 202 to maintain an optimum orientation relative to the crop 22.

[0311] Fig. 10 is a side view of the UAV 1 with the spreader unit 20 adapted for dispensing a liquid product onto a crop 22.

[0312] Referring to fig. 10, there is illustrated a height adjusting arrangement 203, which, in this example, comprises an actuator 2031, here in the form of a reel, or winch, located on the UAV 1, forwardly of the proximal portion 2011 of the spreader unit support 201, and a wire 2032, or band, connected to the spreader unit support 201 and configured to be wound onto the reel. Hence, by controlling the rotation of the reel, a free length of the wire 2032 can be controlled and thus a height position of the distal end 2012 of the spreader unit support 201.

[0313] The reel 2031 may also be controlled by the controller 16.

[0314] Fig. 10 also indicates a sprayer screen 2028, which may be mounted in front of, or behind, as illustrated, the sprayer beam 2021. The sprayer screen 2028 may be essentially vertically oriented, or angled up to about 40 degs relative to the vertical plane, preferably about 45 degs, about 50 degs or about 60 degs.

[0315] Fig. 11 is a top view of the UAV 1 and the field 2, corresponding to fig. 3.

[0316] Figs 12a-12b schematically illustrate the provision of a screening device 2027, 2028, which may be provided in front of and / or behind the spreader unit 202.

[0317] The screening device 2027, 2028 may be provided by a thin sheet of material, which may be partially air permeable. For example, the screening device 2027, 2028 may be about 30-70 % air permeable, preferably about 40-60 % or about 50 %.

[0318] For example, screening device 2027, 2028 may be formed from a frame holding a thin screening fabric, such as a woven or non-woven fabric, that only partially dampens an airflow.

[0319] Alternatively, the screening device 2027, 2028 may be formed from a thin, but rigid, partially permeable sheet of material.

[0320] The screening device 2027, 2028 may extend laterally across all or part of the width of the spreader unit 202.

[0321] The screening device 2027, 2028 may extend vertically at least downwardly from the nozzles 2022 and through a certain height. For example, the vertical extent of the screen may be about the desired height between the nozzles 2022 and the crop 22, such as about 20-60 cm. 1

[0322] Referring to fig. 13, the sprayer beam 2021 may be divided into two or more laterally juxtaposed parts 2021a, 2021b, 2021c, which may be pivotable relative to each other.

[0323] For example, joints 20211 may be provided to render such laterally juxtaposed parts pivotable about one or more axes that are parallel with the working direction Dw. The pivoting about such axes may be controlled by one or more pivot actuators 20212.

[0324] By providing one or more distance sensors 20213 on each part 2021a, 2021b, 2021c, it is possible to control the pivot actuators so as to cause the parts of the spreader section 202 to follow more closely the lateral contour of the crop 22.

[0325] Referring to fig. 14, it is also additionally, or alternatively, possible to provide for a pivoting about one or more pivot axes A3 which are vertical, so that parts of the spreader section 202 can be folded rearwardly. Such folding can be used to provide a reduced width for transport and / or to allow the spreader section 202 to partially yield if colliding with an obstacle.

[0326] In some embodiments, the spreader section 202 may be divided to provide two parts 2021a, 2021c, which can both be folded rearwardly as per fig. 14.

[0327] Fig. 15a illustrate a UAV 1 comprising a spreader unit support 201 and a spreader section 202 configured to spread liquid product.

[0328] Liquid product may be fed from a product tank 170 of the UAV 1, through product channels extending along the spreader unit support 201, to at least one nozzle 2022 of the spreader section 202.

[0329] The feed may be assisted by one or more pumps or valves. The one or more pumps may be arranged on the UAV 1. Alternatively, or additionally, the one or more pumps may be arranged on the spreader section 202.

[0330] The liquid product stored in, and dispensed from, the product tank 170 is usually high dosage product. High dosage product is often broadcasted over a field.

[0331] Broadcast may imply that the product is spread in equal concentration over the entire working width of the spreader section 202 continuously.

[0332] Fig. 15b illustrate an enlarged portion of the encircled section of Fig. 15a.

[0333] Fig. 15b illustrate a low dosage product system 2023, 2024, 2025 configured for distribution of a low dosage product.

[0334] A low dosage product may be a product which is configured to be spread about 5- 100 g / Ha, preferably 5-40 g / Ha or 10-20 g / Ha.

[0335] A low dosage product is preferably distributed via target spreading, which means that it is controllably spread at specific locations of a field. The specific locations may be determined via a prescription map, or via a camera system, identifying weeds, fungi, pests or other treatable plant disease. Target spreading commonly implies that the spreading of product is turned on and off repeatedly while the UAV 1 travels over a field, to not spread the product where not needed.

[0336] Fig. 15b illustrate a cross section in a vertical plane parallel to a working direction

[0337] Dw. Multiple low dosage product systems 2023, 2024, 2025 may be arranged laterally juxtaposed along a sprayer beam 2021 of the spreader section 202. The lateral distance between low dosage product systems 2023, 2024, 2025 may be such that a spreading mist from nozzles 2022 of each low dosage product system 2023, 2024, 2025 effectively covers the entire working width of a sprayer beam 2021.

[0338] The low dosage product system 2023, 2024, 2025 illustrated in 15b comprises a low dosage product tank 2023, a low dosage product pump 2024 and a product pump 2025.

[0339] The low dosage product tank 2023 may comprise an opening for filling low dosage product.

[0340] The low dosage product tank 2023 comprises an outlet, connected via fluid lines to the low dosage product pump 2024.

[0341] The low dosage product tank 2023 may be considerably smaller in volume than a product tank 170 arranged on the UAV 1. A volume of a low dosage product tank 2023 may be less than 10% of a product tank 170 volume, preferably less than 2% or less than 1%.

[0342] A volume of a low dosage product tank 2023 may be about 1 litre.

[0343] The low dosage product pump 2024 may be controllably activated and deactivated by a controller 16. The controller 16 may be an onboard controller of the UAV 1 or a dedicated controller of the spreader unit 20, or of the low dosage system 2023, 2024, 2025.

[0344] The low dosage product pump 2024 may be an electric pump.

[0345] The low dosage product pump 2024 may be activated upon a signal from the controller 16 in response to a camera signal or a position on a prescription map indicating spreading of low dosage product.

[0346] The low dosage product pump 2024 may feed the low dosage product into a second product pump 2025. Alternatively, the low dosage product pump 2024 may feed the low dosage product to a nozzle 2022 of the spreading section 202.

[0347] The low dosage product supply system 2023, 2024, 2025 may alternatively or additionally to the low dosage product pump 2024 comprise a low dosage product valve (not shown).

[0348] A low dosage product valve may control a flow of low dosage product from the low dosage product tank 2025 to the nozzle 2022.

[0349] It will be appreciated if the product lines between the low dosage product pump 2024 and the product tank 2025 are short, to keep the response time of low dosage product application short.

[0350] The low dosage product pump 2024 may feed, or inject, low dosage product into a flow of product created by the product pump 2025. Either by injecting the low dosage product into the product pump 2025, or by injecting the low dosage product into a flow of product generated by the product pump 2025.

[0351] The second product pump 2025 may be configured to feed product from the product tank 170 to the nozzle 2022. When the low dosage product pump 2024 is activated, the flow of low dosage product will merge with the flow of product from the product tank 170 and be dispensed via the nozzle 2022.

[0352] Alternatively, the low dosage product pump 2024 may feed low dosage product from the low dosage product tank 2023 to a dedicated low dosage product nozzle. Such dedicated low dosage product nozzle may be advantageous if mixing of the low dosage product and the product from the product tank 170 contaminates the mixture such that the effect of at least on the products decreases.

[0353] The low dosage product tank 2023 and the low dosage product pump 2024 may be arranged on the UAV 1. In such embodiments, the low dosage product may be injected into a flow of product from the product tank 170 at a more upstream position than what is illustrated in Fig. 15b.

[0354] In such embodiments, the low dosage product may be mixed with product from the product tank 170 at a proximal part 2011 of the spreader unit support 201, and be pumped as a mixture of products through product channels along the spreader unit support 201 and be distributed through the nozzle 2022.

[0355] In further embodiments, multiple low dosage product tanks 2023 and multiple low dosage product pumps 2024 may be arranged on the spreader section 202. The multiple low dosage product tanks 2024 may contain different low dosage product, configured to be spread to different parts of a field.

[0356] Figs 16a-16b schematically illustrate part of a spreader section 102 included in a concept for improving the spread pattern of a spreader unit for spreading solid product.

[0357] The concept disclosed in figs 16a-16b may be used in connection with any of the solid product spreaders disclosed with reference to figs 1-8.

[0358] Fig. 16a illustrates the spreader unit as seen in a cross sectional view taken along a rotation axis of the spreader disc 1022.

[0359] The spreader disc comprises the disc member 10221 and one or more product guides 10222, just like disclosed above. An axial surface of the spreader disc 10221 is exposed towards the product supply 1021. A drive motor 1023 is connected to the spreader disc 1022 by a drive axle 1024.

[0360] The product supply 1021 may be adjustable manually or by one or more actuators. For example, a product supply opening may be movable; a size of the product supply opening may be adjustable; and / or a shape of a product supply opening may be adjustable. Alternatively, or as a supplement, several individually adjustable product supply openings may be provided.

[0361] The spreader disc 1022 may be connected to a subframe 1029 by means of a bearing 1027. The bearing 1027 may be any type of bearing. In the illustrated example, the bearing is a ball bearing.

[0362] The subframe 1029 may be a frame which is configured to hold at least the drive motor 1027 and the spreader disc 1022. Hence, the subframe 1029 may form a unit which may be pivotably mounted relative to the spreader unit or the spreader unit support, to provide adjustability of the axis of rotation of the spreader disc 1022, as described above.

[0363] The bearing 1027 may be mounted relative the subframe 1029 by means of a resilient body 1028, such that the bearing 1027 can perform a limited radial movement relative to the subframe 1029, with the resilient body 1028 biasing the bearing 1027 towards its centered position relative to axis of rotation.

[0364] To this end, a slight radial offset may be provided for between the drive motor 1023 and the spreader disc 1022.

[0365] The resilient body 1028 may be provided from a resiliently flexible material, such as rubber, silicone or thermoplastic elastomer, which allows some movement between the bearing 1027 and the subframe 1029.

[0366] Referring to fig. 16b, a pair of force sensors 10291, 10292, such as piezo sensors, are arranged to measure radial forces exerted by the bearing 1027 towards the subframe 1029.

[0367] In particular, the force sensors 10291, 10292 may be configured to measure compressive forces.

[0368] To this end, the force sensors 10291, 10292 may be configured to measure at least forces along the radial direction of the bearing 1027. The force sensors may be operable between a radially outwardly facing face of the bearing 1027 and an inwardly facing surface of the subframe 1027.

[0369] With the bearing 1027 mounted in a resilient body 1028, a sufficient amount of the radial return force, which is generated onto the bearing as product is thrown off the spreader disc 1022, will be transferred to the force sensors 10291, 10292, such that the radial force generated can be measured.

[0370] By arranging the force sensors 10291, 10292 to measure radial forces along different directions in a plane perpendicular to the axis of rotation of the spreader disc 1022, it is possible to determine the force vector provided by the spreader disc 1022 onto the subframe 1029.

[0371] An angle between directions along which the force sensors 10291, 10292 measure forces may be greater than 0 degs and smaller than 180 degs, but in practice, angles of about 45-135 degs, preferably 80-120 degs may be preferable for a spreader disc 1022 designed to provide a spread pattern over about 120 degs.

[0372] It is possible to provide further sensors. For example, sensors may be provided in pairwise opposite positions, such that forces generated throughout the rotation can be measured. Hence, a particular embodiment would include four sensors mounted pairwise on diametrically opposite sides of the axis of rotation of the spreader disc 1022.

[0373] The force sensors 10291, 10292 may be any sensor capable of detecting a force without requiring much movement, such as piezo sensor.

[0374] The force sensors 10291, 10292 may be connected to a controller, such as e.g. the controller 16.

[0375] The force sensors 10291, 10292 may be combined with other sensors, such as a torque sensor, for determining the torque provided by the spreader disc 1022. The forces measured by the force sensors 10291, 10292 may be associated with the spread pattern, such that an optimal spread pattern may correspond to specific values or ratios of the measured forces. The values may be average or otherwise adjusted values. An average value may be an average value over a rotation or over a certain number of rotations.

[0376] The ratio of the measured forces may also indicate a center of gravity of the spread pattern, such that the ratio of the measured forces may be used to determined how to adjust the product supply 1021 to attain a desired spread pattern.

[0377] Hence, the controller may be configured to receive measurement data from the force sensors 10291, 10292, to analyze the measurement data and to control the adjustment of the product supply 1021 based on the measurement data.

[0378] Referring to fig. 17, there is schematically illustrated a design and an operation principle of the UAV 1, wherein the spreader unit support 101, 201, and thus consequently the spreader section 102, 202, is shifted between a first state, wherein the spreader unit support 101, 201 is in an operating orientation and alternatively in a landing orientation. This principle may be applied to any embodiment disclosed in this document.

[0379] In the operating position, the spreader unit support 101, 201 is oriented such that it inclines downwardly from the product tank 170 towards the spreader section 102, 202. Optionally, such incline may be continuous. Yet optionally, such incline may be constant.

[0380] In particular, the downward incline may be about 10-45 degs to a horizontal plane, preferably about 15-35 degs. In particular cases, the downward incline may be about 10-15 degs, about 15-20 degs, about 20-25 degs, about 25-30 degs, about 30-35 degs, about 35-40 degs or about 40-45 degs.

[0381] In the landing orientation, the spreader unit support 101', 201' is oriented such that it is oriented horizontally, or inclines upwardly from the product tank 170 towards the spreader section 102, 202. Optionally, such incline may be continuous. Yet optionally, such incline may be constant.

[0382] In particular, the upward incline may be about 1-45 degs to a horizontal plane, preferably about, about 5-30 degs. In particular cases, the downward incline may be about 1-5 degs, about 5-10 degs, about 10-15 degs, 15-20 degs, about 20-25 degs, about 25-30 degs, about 30-35 degs, about 35-40 degs or about 40-45 degs.

[0383] An operating method of the UAV 1 may comprise, when a field operation is finished, or paused for replenishment, raising the spreader unit support 101', 201' from an orientation where it is downwardly inclined from the product tank towards the spreader section 102, 202 to an orientation where it is horizontal or upwardly inclined, prior to a landing operation, and in particular prior to a landing operation on a mobile airbase.

Claims

32CLAIMS1. An unmanned aerial vehicle (1) for spreading an agricultural product to a field (2), the unmanned aerial vehicle (1) comprising: a frame (11), one or more rotationally driveable rotors (12) connected to the frame (11), and a spreader unit (10, 20) for spreading agricultural product, the spreader unit (10, 20) comprising a spreader unit support (101, 201) and a spreader section (102, 202), characterised in that a proximal end (1011) of the spreader unit support (101, 201) is connected at the frame (11) and a distal end (1012) of the spreader unit support (101, 201) extends away from the frame (11), the spreader section (102, 202) is connected at the distal end (1012) of the spreader unit support (101, 201), and the distal end (1012) is located outside, as seen in a horizontal direction, a downwash area caused by the rotors (12), in particular during flight in a working direction (Dw).

2. The unmanned aerial vehicle according to claim 1, wherein the distal end (1012) of the spreader unit support (101, 201) is provided forwardly of the unmanned aerial vehicle (1), as seen relative to a working direction (Dw).

3. An unmanned aerial vehicle (1) for spreading an agricultural product to a field (2), the unmanned aerial vehicle (1) comprising: a frame (11) comprising a landing gear (15), one or more rotationally driveable rotors (12) connected to the frame (11), and a spreader unit (10, 20) for spreading agricultural product, the spreader unit (10, 20) comprising a spreader unit support (101, 201) and a spreader section (102, 202), characterised in that a proximal end (1011, 2011) of the spreader unit support (101, 201) is connected at the frame (11) and a distal end (1012) of the spreader unit support (101, 201) extends away from the frame (11), the spreader section (102, 202) is connected at the distal end (1012, 2012) of the spreader unit support (101, 201), and the distal end (1012) of the spreader unit support (101, 201), during flight, is configured to be located at a vertically lower level than the unmanned aerial vehicle (1), in particular at a vertically lower level relative to a lowermost portion of the landing gear (15).

334. The unmanned aerial vehicle (1) as claimed in claim 3, wherein the distal end (1012, 2012) is located outside, as seen in a horizontal direction, a downwash area caused by the rotors (12).

5. The unmanned aerial vehicle (1) as claimed in any one of claims 1 to 4, wherein the spreader unit support (101, 201) is rigid between, in particular from, the proximal end (1011, 2011) and, in particular to, the distal end (1012).

6. The unmanned aerial vehicle (1) as claimed in any one of claims 1 to 5, wherein the spreader unit support (101, 201) presents a continuous axial direction from the proximal end (1011, 2011) to the distal end (1012).

7. The unmanned aerial vehicle (1) according to any of claims 1 to 6, wherein the proximal end (1011, 2011) of the spreader unit support (101, 201) is pivotably connected to the UAV (1).

8. The unmanned aerial vehicle (1) according to claim 7, wherein the spreader unit support (101, 201; 101', 201') is pivotable between an operating orientation, wherein the spreader unit support (101, 201; 101', 201') provides a generally downward incline from its proximal end to its distal end, and a landing orientation, wherein the spreader unit support (101, 201; 101', 201') is horizontal, or provides a generally upward incline from its proximal end to its distal end.

9. The unmanned aerial vehicle (1) according to any one of claims 1 to 8, wherein the spreader unit (10, 20) comprises a distance sensor (1025) and a height adjusting actuator (1031), the distance sensor (1025) being configured to measure a height from the spreader unit to a crop (22) and / or ground, and the height adjusting actuator (1031) being configured to adjust the spreader unit support (101, 201) so as to keep the height of the spreader unit (10, 20) at a predetermined height above the crop (22) and / or ground.

10. The unmanned aerial vehicle (1) according to any of claims 1 to 9, wherein the spreader unit (10, 20) further comprises an anti-collision system comprising at least one collision detection sensor (10214, 20214), wherein the collision detection sensor (10214, 20214) is arranged at the distal end of the spreader unit support (101, 201), such that the collision detection sensor (10214, 20214) is located outside, as seen in a horizontal direction, a downwash area caused by the rotors (12) and / or located at a vertically lower level than the unmanned aerial vehicle (1).

11. The unmanned aerial vehicle (1) according to claim 10, wherein the anticollision system is configured to modify a flight path of the unmanned aerial vehicle (1) to avoid collision with an obstacle detected by the collision detection sensor (10214, 20214).

12. The unmanned aerial vehicle (1) according to any of the claims 1 to 11, wherein the spreader unit support (101, 201) further comprises a release mechanism, configured to release the spreader unit support (101, 201) from the unmanned aerial vehicle (1) when subjected to a predetermined external force.

13. The unmanned aerial vehicle (1) according to any of claims 1 to 12, wherein the spreader unit (10, 20) is connected to the spreader unit support (101, 201) via a parallelism mechanism, configured to control a pitch of the spreader unit (10, 20), in particular of the spreader section (102, 202).

14. The unmanned aerial vehicle (1) according to any of claims 1 to 13, wherein one or more of the rotors (12) is angled relative to the frame such that the downwash airstream created by the one or more of the rotors (12) is angled away from the spreader unit (10, 20), in particular as seen in the working direction (Dw).

15. The unmanned aerial vehicle (1) according to any of claims 1 to 14, wherein the spreader unit (10, 20) further comprises a roll mechanism, configured to control a roll of the spreader unit (10, 20), in particular of the spreader section (102, 202), around an axis parallel to the working direction (Dw).

16. The unmanned aerial vehicle (1) according to any one of the preceding claims, wherein the spreader section (102) comprises a rotatably drivable spreader disc (1022) and a product supply (1021), configured to feed product to the spreader disc (1022), whereby the spreader disc (1022) is configured to spread the product.

17. The unmanned aerial vehicle (1) according to claim 16, wherein the spreader unit (10, 20) further comprises: a tilt mechanism (1026) connected to the spreader disc (1022) and comprising a controllable actuator, wherein the controllable actuator is configured to control a tilt angle of a rotation axis (Rd) of the spreader disc (1022) relative to the product supply (1021), such that a spreading pattern from the spreader unit (10, 20) is controllable to be asymmetric relative to a vertical plane (Pw) comprising a working direction (Dw).

18. The unmanned aerial vehicle (1) according to claim 17, wherein the tilt mechanism (1026) further comprises a second controllable actuator configured to control asecond angle of the rotation axis (Rd) of the spreader disc (1022) relative to the product supply, such that the spreading pattern from the spreader unit (10, 20) is controllable to be asymmetric relative to a vertical plane (Pt) perpendicular to the working direction (Dw).

19. The unmanned aerial vehicle (1) according to claim 17 or 18, wherein the tilt mechanism comprises a pivot joint configured to allow the spreader disc (1022) and a spreader disc drive unit (1023) to tilt relative to the product supply (1021).

20. The unmanned aerial vehicle (1) according to any of claims 17-19, wherein the tilt mechanism (1026) comprises a coupling allowing an angular offset between the spreader disc rotation axis (Rd) and a spreader disc drive unit drive axle (1024).

21. The unmanned aerial vehicle (1) according to any of claims 16-20, wherein the spreader disc (1022) comprises one or more radial guides (10222) extending along a surface of the spreader disc (1022) which faces the product supply (1021), wherein the radial guides (10222) are configured to hurl the agricultural product during rotation of the spreader disc (1022).

22. The unmanned aerial vehicle (1) according to any one of claims 16-21, wherein the spreader unit (10, 20) further comprises a product tank (14), mounted on a frame (11) of the unmanned aerial vehicle (1) and wherein the product supply (1021) is configured to control a supply of the product from the product tank (14) to the spreader disc (1022).

23. The unmanned aerial vehicle (1) according to any one of claims 1 to 15, wherein the spreader section (202) comprises at least one sprayer beam (2021) for spreading of a liquid product.

24. The unmanned aerial vehicle (1) according to claim 23, wherein the sprayer beam, when in an operating position, presents a width which is greater than a width of the UAV frame, preferably greater than a total UAV width including rotors.

25. The unmanned aerial vehicle (1) according to claim 23 or 24, wherein the spreader unit (10, 20) further comprises a pivot connection (20211), connecting a pair of laterally juxtaposed parts (2021a, 2021b, 2021c) of the sprayer beam (2021), such that at least a portion of the sprayer beam (2021) is upwardly and / or rearwardly foldable.

26. The unmanned aerial vehicle (1) according to claim 25, wherein the spreader unit (10, 20) further comprises at least one actuator (20212), which is configured to control36 the pivot connection (20211), and such that a relative pivot position of the parts (2021a, 2021b, 2021c) of the sprayer beam (2021) is controllable.

1. The unmanned aerial vehicle (1) according to any of claims 23 to 26, wherein the spreader unit (10, 20) further comprises at least one sprayer screen (2027, 2028) extending laterally along and downwardly from the sprayer beam (2021).

28. The unmanned aerial vehicle (1) according to any of claims 23 to 27, wherein the sprayer beam (2021) comprises at least one low dosage product supply system (2023, 2024, 2025).

29. The unmanned aerial vehicle (1) according to claim 28, wherein the low dosage product supply system (2023, 2024, 2025) comprises: at least one low dosage product tank (2023), configured for storing a low dosage product for target spreading, and at least one low dosage product supply controller (2024), configured for controlling a flow of the low dosage product to a product pump (2025) or to a nozzle (2022).

30. The unmanned aerial vehicle (1) according to any of the preceding claims, wherein the spreader unit (10, 20) further comprises at least one navigation sensor 10215, 20215, which is arranged at the distal end (1012, 2012) of the spreader unit support (101, 201).

31. The unmanned aerial vehicle (1) according to any of the preceding claims, wherein the spreader unit support (101, 201) is hollow and presents a cross sectional area which expands towards the distal end (1012, 2012).

32. A spreader unit configured for being carried by an unmanned aerial vehicle (1) for spreading an agricultural product to a field, the unmanned aerial vehicle (1) comprising a frame (11) and one or more rotationally driveable rotors (12) connected to the frame (11), the spreader unit (10, 20) for spreading agricultural product comprising at least one sprayer beam (2021) for spreading of a liquid product, characterized by a pivot connection (20211) connecting a pair of laterally juxtaposed parts (2021a, 2021b, 2021c) of the sprayer beam (2021), such that at least a portion of the sprayer beam (2021) is upwardly and / or rearwardly foldable.

33. A spreader unit configured for being carried by an unmanned aerial vehicle (1) for spreading an agricultural product to a field, the unmanned aerial vehicle (1)37 comprising a frame (11) and one or more rotationally driveable rotors (12) connected to the frame (11), the spreader unit (10, 20) comprising a product tank (14), a spreader unit support (101, 201) and a spreader section (102, 202), supported by the spreader unit support (101, 201), characterized in that the spreader unit support (101, 201) is configured as an elongate part, having a length sufficient to position the spreader section (102, 202) outside a downwash area of the unmanned aerial vehicle (1) when the spreader unit is mounted to the unmanned aerial vehicle (1).

34. The unmanned aerial vehicle (1) according to claim 33, wherein the spreader unit support (101, 201) is hollow and presents a cross sectional area which expands towards a distal end (1012, 2012) of the spreader unit support (101, 201).

35. An unmanned aerial vehicle (1) comprising a spreader unit (10, 20) for spreading an agricultural product, the spreader unit (10, 20) comprising: a product supply (1021) configured to feed product to a rotatably driveable spreader disc (1022), wherein the spreader disc (1022) is configured to spread the product outwardly from the spreader disc (1022), characterized by a tilt mechanism (1026) connected to the spreader disc (1022) and comprising a controllable actuator, wherein the controllable actuator is configured to control a tilt angle of a rotation axis (Rd) of the spreader disc (1022) relative to the product supply (1021), such that a spreading pattern from the spreader unit (10, 20) is controllable to be asymmetric relative to a vertical plane (Pt) comprising a working direction (Dw).

36. A method for spreading an agricultural product over a field (2), the method comprising: causing an unmanned aerial vehicle (1) to fly over the field (2), causing the unmanned aerial vehicle (1) to spread at least one agricultural product from the unmanned aerial vehicle (1) via a rotating spreader disc (1022), and causing a tilting of a rotation axis (Rd) of the spreader disc relative to a frame (11) of the unmanned aerial vehicle (1) to cause an asymmetric spreading pattern relative to a vertical plane (Pw) comprising a working direction (Dw).

37. The method according to claim 36, wherein the method is applied along a field border (21a, 21b) or an irregularity of the field (2), such that a shorter throw is provided38 in a direction from the unmanned aerial vehicle (1) towards the field border (21a, 21b) or irregularity.

38. The method according to claim 36 or 37, further comprising, in connection with said tilting, adjusting an rpm with which the spreader disc (1022) is caused to rotate.

39. The method according to any one of claims 36-38, further comprising, in connection with said tilting, adjusting a rate with which the agricultural product is fed towards the spreader disc (1022).

40. A spreader unit (10, 20), in particular for being carried by an unmanned aerial vehicle (1), for spreading an agricultural product to a field, the spreader unit (10, 20) comprising: a rotatably driveable spreader disc (1022), and a product supply (1021), configured to supply the product to an axially exposed face of the spreader disc (1022), characterized by at least two force sensors (10291, 10292), each configured to measure a radial force vector exerted by the spreader disc (1022), wherein the force sensors (10291, 10292) are configured to detect force vectors along two different directions in a plane perpendicular to a rotation axis (Rd)of the spreader disc (1022).

41. The spreader unit (10, 20) as claimed in claim 40, wherein the product supply is adjustable along at least one of a radial direction of the spreader disc (1022) and a rotation direction of the spreader disc (1022).

42. The spreader unit (10, 20) as claimed in claim 40 or 41, wherein the force sensors (10291, 10292) are mounted in parallel with an elastic member (1028).

43. The spreader unit (10, 20) as claimed in any one of claims 40-42, wherein the force sensors (10291, 10292) are provided between a bearing, which rotationally supports the spreader disc (1022) and a subframe (1029), which supports the spreader disc (1022) and a drive unit (1023).

44. The spreader unit (10, 20) as claimed in any one of claims 40-43, wherein the force sensors (10291, 10292) are configured to measure forces along respective directions making an angle of about 45-135 degs relative to each other, preferably 80-120 degs relative to each other.3945. A method of adjusting a spread pattern of a spreader unit (10, 20) for spreading an agricultural product to a field, wherein the spreader unit (10, 20) comprises a rotatably driveable spreader disc (1022), and a product supply (1021), configured to supply the product to an axially exposed face of the spreader disc (1022), wherein the method comprises: causing the product supply (1021) to feed product to the spreader disc (1022) while the spreader disc (1022) is caused to rotate, measuring at least two radial force vectors exerted by the spreader disc (1022) during said feeding and rotation, said radial force vectors being measured along different directions in a plane perpendicular to a rotation axis (Rd) of the spreader disc (1022), and adjusting the product supply (1021) relative to the spreader disc (1022) based on said force vectors.

46. Use of an unmanned aerial vehicle (1) as claimed in any one of claims 1 to 31, comprising: flying the unmanned aerial vehicle (1) in a first straight path over a predefined area while distributing agricultural product to the area, turning the unmanned aerial vehicle (1) about 180 degrees, flying the unmanned aerial vehicle (1) in a second straight path, wherein the second straight path is parallel to, and laterally spaced from, the first straight path.

47. The use according to claim 46, further comprising alternately flying the unmanned aerial vehicle (1) in multiple straight paths and alternately turning the unmanned aerial vehicle about 180 degrees, to effectively cover the area.

48. The use according to claim 47, wherein each straight path is parallel with, and laterally spaced from, the previously flown straight path.

49. The use according to claim 47 or 48, wherein the multiple paths are nonoverlapping.

50. Use of an unmanned aerial vehicle (1) as claimed in any one of claims 28 to 29, comprising: flying the unmanned aerial vehicle (1) over a predefined area, distributing a first agricultural product configured for broadcasting through a primary product supply system, distributing a low dosage agricultural product configured for target spreading through a low dosage product supply system.4051. A method of operating an unmanned aerial vehicle (1), the unmanned aerial vehicle comprising: a frame (11), one or more rotationally driveable rotors (12) connected to the frame (11), and a spreader unit (10, 20) for spreading agricultural product, the spreader unit (10, 20) comprising a spreader unit support (101, 201) and a spreader section (102, 202), wherein a proximal end (1011) of the spreader unit support (101, 201) is connected at the frame (11) and a distal end (1012) of the spreader unit support (101, 201) extends away from the frame (11), wherein the spreader section (102, 202) is connected at the distal end (1012) of the spreader unit support (101, 201), and wherein the distal end (1012) is located outside, as seen in a horizontal direction, a downwash area caused by the rotors (12), in particular during flight in a working direction (Dw), the method comprising when a field operation is finished, or paused for replenishment, raising the spreader unit support (101', 201') from an orientation where it is downwardly inclined from the proximal end (1011) towards the distal end (1012) to an orientation where it is horizontal or upwardly inclined, prior to a landing operation, and in particular prior to a landing operation on a mobile airbase.

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