Patent Description:
Work of the presently named inventors, to the extent it is described in the background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.

Unmanned aerial vehicles (UAVs) are becoming popular in a number of applications, including aerial photography, parcel delivery and the like. UAVs are vehicles which travel through the air and are unmanned (that is, they are not controlled by a human user travelling on-board the UAV). UAVs may be electrically propelled (e.g. by a propeller powered by an electric motor) or propelled by other means (e.g. by burning a combustible fuel such as kerosene). Even non-electrically propelled UAVs, however, often require electrical power for on-board electrical systems (e.g. navigation systems, communication systems and the like). UAVs often incorporate a battery to power the UAV's propulsion and/or on-board systems.

A problem is that a battery contains a finite amount of electrical power and must therefore be regularly recharged. This requires the UAV's operation to be regularly interrupted to enable the UAV to return to a predetermined location at which its battery can be recharged. The UAV must then wait until the battery is sufficiently recharged before it can return to its operation. This results in significant UAV down time in which the UAV cannot be used.

One proposal is to replace a UAV's depleted battery with a newly charged battery instead of charging a depleted battery when it remains installed in the UAV. This can reduce the UAV down time because the UAV no longer has to wait until its battery has been recharged. Rather, it must only wait for the battery replacement operation to be completed. A problem, however, is how to undertake UAV battery replacement efficiently.

Prior art includes: <CIT>, <CIT> and <CIT>.

The present disclosure is defined by the claims.

<FIG> show example types of UAVs. <FIG> shows a fixed-wing type UAV 100A and <FIG> shows a rotary type UAV 100B. The present disclosure relates to allowing UAVs such as these to quickly change their battery whilst in flight. In particular, the present disclosure allows a first battery to be replaced by a second battery by way of the second battery contacting the first battery, pushing it out and taking its place in a battery bay of the UAV. This occurs under the momentum of the UAV as it flies.

A battery bay may be considered to be a compartment, not necessarily wholly enclosed, for holding a battery which powers (at least in part) the UAV. It may retract into the main body whilst in flight for example using a stepper motor or hydraulic mechanism. It may be fixed to the structure of the UAV, for example under the main body or a wing. The exterior of the battery bay may be shaped such as to have aerodynamic properties to reduce drag. The exterior of the battery bay may be configured such as to increase drag and slow the UAV as it lands for a battery exchange. There may be more than one battery bay in a UAV.

<FIG> shows such an example battery exchange system <NUM> for the fixed-wing type UAV 100A. The UAV 100A has a battery bay <NUM> which is shown as exposed in <FIG> and which comprises a first battery 202A. The battery bay <NUM> is shown in a cut-away view so that the battery 202A within the battery bay can be seen in <FIG>. In reality, the battery 202A will not be seen in the battery bay when the UAV 100A is viewed from the perspective shown in <FIG>. The battery bay comprises a shell <NUM> and a column <NUM>, to be described later. The UAV 100A is approaching a battery station <NUM>. The battery station <NUM> comprises a second battery 202B releasably attached to a stand <NUM>. The stand <NUM> comprises a battery holding portion <NUM> and a support shaft <NUM>. The stand <NUM> is mounted on a support portion <NUM>. The support portion <NUM> is rotatable in the direction of the arrows <NUM> and slidable along a rail <NUM> in the direction of the arrows <NUM>. The support shaft <NUM> is mounted to the support portion <NUM> by way of a pivot <NUM>, which allows the stand <NUM> (and therefore the battery 202B) to move about the pivot in the direction indicated by the arrows <NUM>. This allows the position of the battery 202B to be adjusted so as to optimise the position of the battery 202B in preparation for making contact with the battery 202A held in the battery bay <NUM> of UAV 100A as it flies, pushing the battery 202A out of the battery bay <NUM> and positioning itself in the battery bay <NUM> in place of the battery 202A. Upon being correctly positioned in the battery bay <NUM>, the battery <NUM> is released from the battery holding portion <NUM> of the stand and the UAV 100A is thus able to fly off, its battery replaced. Note that this is done at least with a contribution from the force of impact between the batteries 202A and 202B as the UAV 100A flies past the battery station <NUM>. The batteries 202A and 202B each comprise a tapered protrusion <NUM> and a tapered cavity <NUM> with a shape which complements the shape of the tapered protrusion <NUM>. Upon contact of the batteries 202A and 202B, the protrusion <NUM> of the battery 202A enters the cavity <NUM> of the battery 202B. This aligns the batteries 202A and 202B as they come into contact, thereby allowing the battery exchange to occur smoothly.

In embodiments, the protrusion <NUM> may be shaped at least in part as pyramidal, conical or frustroconical with a respectively complementary cavity <NUM>. The shape of protrusion <NUM> may be geometrically irregular. The battery as mentioned herein may comprise a plurality of cells in a package. Such cells may be for example Li-ion or Li-polymer cells. Embodiments of the disclosure therefore provide that the entrance or approach of the UAV into the battery station <NUM> does not require total precision; the alignment of the batteries may compensate for an inaccurate entry or approach for example caused by calibration error or other factors such as wind or weather conditions. The engagement of the protrusion <NUM> into the cavity <NUM> may provide a final guide for the UAV into battery station <NUM>.

Upon ejection of the battery 202A from the battery bay <NUM>, the battery 202A lands on a first conveyor belt 214A (an example of a transporter), which is moving in the direction of the arrow <NUM>. The battery 202A is then aligned lengthways by tapered channelling walls <NUM>. The tapered channelling walls <NUM> are walls which form a channel through which the battery 202A travels. The distance between the walls is gradually reduced along the direction of travel of the battery 202A along the conveyor belt 214A so that battery 202A is aligned lengthways along its direction of travel.

After being aligned and reaching the end of the first conveyor belt 214A, the battery arrives at an analysis device <NUM> and turntable <NUM>. The analysis device <NUM> comprises a support column <NUM> and an arm <NUM> slidably attached to the support column <NUM>. An electric motor (not shown) causes the arm <NUM> to move up and down relative to the support column <NUM> in the direction of the arrows <NUM>. The arm <NUM> comprises two electrodes <NUM> configured to contact positive and negative terminals of the battery 202A (the arm <NUM> is movable in a downwards direction until the electrodes <NUM> each contact a respective one of the positive / negative battery terminals). The contact between the electrodes <NUM> and the battery terminals allows a voltage output by the battery to be measured by appropriate circuitry (not shown) of the analysis device. This allows the remaining charge of the battery to be determined. Furthermore, depending on the polarity of the measured voltage (which will be either positive or negative, depending on which of the positive / negative terminals each of the electrodes <NUM> makes contact with and, thus, on the orientation of the battery), the turntable <NUM> is configured to rotate the battery 202A by <NUM> degrees in order to ensure that the battery is at a predetermined orientation. The voltage measuring circuitry controls an electric motor (not shown) to rotate the turntable depending on the measured voltage polarity. The battery should be orientated such that the end with the protrusion <NUM> is at the front in the direction of travel of the battery. The terminals on the battery are arranged such that the voltage polarity should be positive (or negative) when the battery is correctly orientated. Thus, if the measurement of the battery voltage by the electrodes <NUM> is positive (or negative), then the orientation of the battery is not changed (that is, the turntable <NUM> does not turn the battery). On the other hand, if the measurement of the battery voltage by the electrodes <NUM> is negative (or positive), then the orientation of the battery is changed (that is, the turntable <NUM> does turn the battery). Other sensors may be present such as an NFC sensor which reads a Near Field Communications, NFC, device in the battery. The NFC device may contain authenticity information pertaining to the battery which transfers to the sensor. The NFC device may contain information written to the NFC device by the UAV such as information pertaining to the journey undertaken by the UAV. Such information may be transferred to the sensor. In embodiments, with NFC read/write devices mounted in the protrusion <NUM> and cavity <NUM>, information could be transferred from battery to battery at the point of battery exchange. This may for example provide an audit trail, logging information or enable some statistical analysis when information from a battery is retrieved.

The battery 202A is then passed to a second conveyor belt 214B (an example of a transporter), which is moving in the direction of the arrow 215B. The battery 202A (now correctly orientated) travels along the second conveyor belt 214B until it reaches a charging carousel <NUM> (an example of a charger). The charging carousel <NUM> comprises a plurality of charging cavities, each shaped so as to receive and contain a battery. As the battery approaches the end of the second conveyor belt 214B, the charging carousel <NUM> is rotated such that an empty charging cavity <NUM> is positioned at the end of the second conveyor belt. When the battery 202A reaches the end of the second conveyor belt 214B, it will drop under gravity into the empty charging cavity. Due to the battery 202A having been previously orientated such that its protrusion <NUM> is positioned at the front in the direction of travel, the battery drops protrusion-first into the empty charging cavity <NUM>. The charging cavities other than empty charging cavity <NUM> each contain a battery in this example. Each charging cavity <NUM> comprises a pair of charging contacts 227A and 227B which are connected to a power supply (not shown) and which make electrical contact with the terminals of the battery positioned within that charging cavity so as to electrically charge the battery. Each battery comprises a pair of battery terminal portions 303A and 303B which respectively make electrical contact with the charging contacts 227A and 227B when battery is held in the charging cavity.

Each charging cavity comprises a notch <NUM> such that a surface of the battery held in the charging cavity is exposed. This allows the battery holding portion <NUM> of the stand <NUM> to engage with the exposed battery surface. In embodiments, the exposed battery surface is magnetically attracted to the battery holding portion <NUM>. The stand <NUM> (by rotation of the various battery station components in the directions of the arrows <NUM>, <NUM> and <NUM>) is thus able to pick up a battery from the charging carousel <NUM> and suitable position that battery so as to allow that battery to replace the battery of the next UAV 100A which flies in for a battery change.

<FIG> show perspective views of an example battery <NUM> (of which batteries 202A and 202B are examples). <FIG> shows a front perspective view (showing the tapered protrusion <NUM>) and <FIG> shows a rear perspective view (showing the tapered cavity <NUM>). The battery <NUM> is substantially cuboidal in shape. At one end, there is a flat face 300A on which the tapered protrusion <NUM> is formed. The cross-sectional area of the tapered protrusion <NUM> is less than that of the flat face 300A and the tapered protrusion <NUM> is positioned centrally on the flat face 300A, thereby resulting in a portion <NUM> of the flat face 300A bordering the tapered protrusion <NUM> remaining exposed. Similarly, at the other end, there is a flat face 300B within which the tapered cavity <NUM> is formed. The cross-sectional area of the tapered cavity <NUM> is less than that of the flat face 300B and the tapered cavity is positioned centrally on the flat face 300A, thereby resulting in a portion <NUM> of the flat face 300B bordering the tapered cavity <NUM> remaining exposed. The exposed portions <NUM> and <NUM> of the flat faces 300A and 300B allow the battery to engage with one or more retractable lugs for holding the battery in place in the battery bay <NUM> of the UAV.

The four surfaces 305A-D (of which 305B and 305A are visible in <FIG> and of which 305B and 305C are visible in <FIG>) connecting the flat faces 300A and 300B are each identical and concave in shape such that the battery 202A has a constant cross section when viewed from either of the ends defined by the flat faces 300A and 300B. Each of the surfaces 305A-D comprises a pair of battery terminal portions 303A and 303B (which are positive and negative, respectively, or vice versa). In embodiments, the positive battery terminal portions of the surfaces 305A-D are electrical conductors all of which are connected to the same positive terminal of the battery <NUM>. Similarly, the negative battery terminal portions of the surfaces 305A-D are electrical conductors all of which are connected to the same positive terminal of the battery <NUM>. The battery <NUM> can therefore be charged or discharged by connecting charging or discharging electrodes, respectively, to the battery terminal portions 303A and 303B of any one of the surfaces 305A-D. The orientation of the battery surfaces 305A-D when the battery lands on the first carousel therefore does not matter because, whatever the orientation of the surfaces 305A-D, one set of battery terminal portions 303A and 303B will engage with the charging contacts 227A and 227B of the charging cavity (allowing the battery to be charged). Also, when the battery is placed within the battery bay <NUM>, one set of battery terminal portions 303A and 303B will engage, respectively, with electrodes 408A and 408B of the battery bay <NUM>, therefore allowing electrical power to be supplied to the UAV 100A by the battery. Each of the battery terminal portions 303A and 303B comprises a strip of electrically conductive material extending along the length of the battery from one end of the battery to the other (each end of the battery being defined by one of the flat faces 300A and 300B).

<FIG> show the battery bay <NUM> in more detail. The battery bay comprises a shell <NUM> and a column <NUM>. The column <NUM> attaches the shell <NUM> to the main body of the UAV 100A. The shell defines an internal space <NUM> for receiving the battery <NUM>. <FIG> shows a perspective view of the battery bay <NUM> as viewed from the front of the UAV 100A as it travels. <FIG> shows the same view of the battery bay <NUM> rotated by <NUM> degrees so that the internal space <NUM> defined by the shell <NUM> can be seen more clearly. In embodiments, column <NUM> and the bay <NUM> may retract at least in part into the body of the UAV.

The internal space <NUM> is dimensioned so that the battery enters the internal space via opening <NUM> and is secured in place within the internal space <NUM>. During a battery exchange operation, upon making contact with a replacement battery, the battery may then exit the internal space via exit <NUM>. Whilst the UAV 100A is flying, the battery is held in place in the internal space by way of ribs <NUM>, which each engage with a respective edge defined between two of the surfaces 305A-D, and by way of retractable lugs 403A and 403B. The ribs are separated along the length of the shell <NUM> by way of by a distance w<NUM>. The shell <NUM> comprises two planar side walls 407A and 407B and a convex top wall 407C. It is not necessary for the walls to be solid; they may comprise a frame with apertures to provide rigidity or stiffness whilst saving material and weight. The convex shape of the top wall 407C complements the concave shape of the surfaces 305A-D of the battery. The battery is thus secured in place in the internal space by way of the lugs 403A and 403B, ribs <NUM>, side walls 407A and 407B and top wall 407C such that relative movement between the battery and shell is prevented.

The top wall 407A comprises a pair of electrodes 408A and 408B. When the battery is held within the internal space <NUM>, the convex surface of the top wall 407A engages with the concave surface of one of the battery surfaces 305A-D (the one of the battery surfaces depending on the orientation of the battery when it enters the internal space). This causes the electrodes 408A and 408B to electrically contact, respectively, the battery terminals 303A and 303B on that battery surface. The electrodes 408A and 408B are electrically connected to the electrical components (not shown) of the UAV 100A, thereby allowing the electrical components of the UAV to be powered by the battery.

<FIG> show the stand <NUM> in more detail. As shown in <FIG>, the stand <NUM> comprises the support shaft <NUM> on which the battery holding portion <NUM> is mounted. The battery holding portion comprises a support layer <NUM> and in some embodiments a permanent magnet layer <NUM>. The support shaft <NUM> and support layer <NUM> may be formed from a single piece of rigid material. The permanent magnet layer <NUM> comprises a permanently magnetic material to which ferromagnetic materials such as iron, nickel and cobalt are attracted. The battery terminal portions 303A and 303B comprise a ferromagnetic material which is attracted to the magnetic layer <NUM>. Alternatively or in addition, a portion of each of the surfaces 305A-D of the battery other than the battery terminal portions 303A and 303B may comprise a ferromagnetic material which is attracted to the magnetic layer. The magnetic layer has a convex shape which complements with and engages with the concave shape of the battery surfaces 305A-D. Thus, a battery <NUM> located in a charging cavity <NUM> of the charging carousel <NUM> may be extracted from the charging cavity by way of the battery surface exposed by the notch <NUM> of the charging cavity being attracted to the permanent magnet layer <NUM> of the battery holding portion <NUM> and engaging with the magnetic layer. When the support shaft <NUM> is then rotated about the pivot <NUM>, the battery is extracted from the charging cavity and is releasably mounted on the battery holding portion <NUM> via the magnetic attraction between the battery surface (battery surface 305D in this case) and permanent magnet layer <NUM>. This is shown in <FIG>. The battery can then be positioned as exemplified in <FIG> so as to be ready to replace a battery in the battery bay <NUM> of the UAV 100A when it flies towards the battery station <NUM>. The complementary concave shape of the battery surface and convex shape of the magnetic layer <NUM> helps alleviate rotational movement of the battery relative to the battery holding portion <NUM>, thereby helping to ensure that the battery is correctly positioned for UAV battery replacement. In embodiments, instead of or in addition to the use of magnetic layer <NUM>, the battery may be releasably secured in a top layer of the stand, the top layer forming a slot, ratchet or geared mechanism providing sufficient resistance for battery exchange to take place under the force of landing.

The width w<NUM> of the battery holding portion <NUM> is less than the width w<NUM> defined between the ribs <NUM> of the shell <NUM> of the battery bay <NUM>. This allows the battery to enter the internal space <NUM> of the shell whilst still attached to the battery holding portion <NUM>. The battery then pushes out the old battery to be replaced in the internal space and, once the battery is secured within the internal space <NUM> by way of the lugs 403A and 403B, the battery is pulled away from the magnetic layer <NUM> of the battery holding portion <NUM> by the momentum of the UAV 100A. The battery holding portion <NUM> is then free to pick up another battery to facilitate a future UAV battery change. The strength of the magnetic attraction between the battery surface and permanent magnet layer <NUM> is determined to be large enough to securely hold the battery 202B in position as the battery 202A of the UAV to be replaced initially makes contact with the battery 202B but small enough such that the battery 202B is released from the battery holding portion <NUM> once the battery 202B is secured in place within the shell <NUM>.

<FIG> show an example mechanism by which a first battery 202A held in the battery bay <NUM> of the UAV 100A is replaced by a second battery 202B. Each of <FIG> is a view of the battery bay <NUM> shown from an aerial perspective with the top wall 407C cut-away.

<FIG> shows the situation at a first time at which the first battery 202A is held in the battery bay <NUM> and the UAV 100A is approaching the second battery 202B held by the stand <NUM> (not seen in <FIG>). The second battery 202B is secured within the internal space <NUM> defined by the shell <NUM>. More specifically, the battery 202B is held between respective inner surfaces <NUM> of the walls 407A and 407B and between sets of retractable lugs 403A and 403B. The top two lugs of the sets of lugs at each end of the shell <NUM> are seen in <FIG>. Each lug 403A at one end of the shell is connected to a corresponding lug 403B at the other end of the shell via a rigid connecting portion <NUM>, which extends through a channel defined within a respective one of the walls 407A and 407B. For clarity, the connecting portion <NUM> is denoted for the top two lugs 403A and 403B for the wall 407B only. However, the other lugs (in particular, the bottom two lugs for the wall 407B and the top and bottom two lugs for the wall 407A) are connected by a connecting portion in the same way with the same configuration. The connecting portion <NUM> of the wall 407B is connected to an inner surface of the wall channel via a pivot <NUM> and a compression spring <NUM> (the spring is an example of a member which is resilient when compressed under a mechanical force).

Each of the lugs 403A comprises a pair of flat surfaces which taper in a direction from the inner surface <NUM> towards the internal space <NUM> defined within the shell <NUM>. A first one of the flat surfaces of each lug 403A is substantially flush with the exposed flat portion <NUM> of the battery 202A, thus holding the battery in place in the shell <NUM>. A second one of the flat surfaces of the lug 403A is exposed so as to make contact with the exposed flat portion <NUM> of the new battery 202B during the battery exchange. Each of the lugs 403B also comprises a pair of flat surfaces which taper in a direction from the inner surface <NUM> towards the internal space <NUM> defined within the shell <NUM>. A first one of the flat surfaces of each lug 403B is substantially flush with the exposed flat portion <NUM> of the battery 202A, thus holding the battery in place in the shell <NUM>. A second one of the flat surfaces of the lug 403B is exposed.

As shown in <FIG>, during the battery exchange, the exposed flat portion <NUM> of the new battery 202B pushes on the second flat surface of each lug 403A. This causes the lug 403A and connecting portion <NUM> to rotate about the pivot <NUM>, compressing the spring <NUM>. The rotation results in the lug 403A retracting into the cavity in the wall 407B and in the connecting portion <NUM> pulling the lug 403B so that the lug 403B is also retracted into the cavity in the wall 407B.

The retraction of the lugs 403A allows the new battery 202B to make flush contact with the old battery 202A (so that the protrusion <NUM> of the old battery 202A enters and sits flush within the cavity <NUM> of the new battery, the protrusion <NUM> and cavity <NUM> being complementary shapes). The retraction of the lugs 403B allows the old battery 202A to slide out of the internal space <NUM> and onto the first conveyor belt 214A. Under the momentum of the UAV, the new battery 202B is thus able to make contact with, push out and replace the old battery 202A in the internal space <NUM>.

As the old battery 202A is pushed out of the internal space by the new battery 202B, the boundary <NUM> between the batteries reaches the tapered ends of the lugs 403B and the old battery 202A falls out of the shell <NUM>. The lugs 403A and 403B are then urged back to their original position by the spring <NUM> such that the first one of the flat surfaces of each lug 403A becomes substantially flush with the exposed flat portion <NUM> of the new battery 202B and the first one of the flat surfaces of each lug 403B becomes substantially flush with the exposed flat portion <NUM> of the new battery 202B. The lugs 403A and 403B thus secure the new battery 202B in place within the shell <NUM>. This situation is shown in <FIG>.

<FIG> shows the example battery exchange system <NUM> when the UAV is a rotary type UAV 100B instead of a fixed-wing type UAV 100A. The arrangement shown in <FIG> is the same as that shown in <FIG> except that the position of the new battery 202B has been adjusted in order to allow battery replacement for the UAV 100B, which approaches the battery station <NUM> vertically instead of horizontally. The position of the new battery has been adjusted by adjusting the position of the stand <NUM> so that the direction of the cavity <NUM> of the new battery 202B points upwards so as engage with the protrusion <NUM> of the old battery 202A and so that the old battery 202A is pushed out by the new battery 202B as the UAV approaches the new battery vertically. The position of the stand <NUM> has been adjusted by the support portion <NUM> moving along the rail <NUM> in the direction of the arrow <NUM>, the support portion <NUM> rotating by <NUM> degrees in the direction of the arrow <NUM> and the support shaft <NUM> rotating about the pivot <NUM> by <NUM> degrees in the direction of the arrow <NUM>. The movement of the support portion along the rail <NUM> helps ensure that the UAV 100B encounters the new battery 202B at substantially the same spatial position relative to the first conveyor belt 214A as described for the UAV 100A, thereby allowing the ejected old battery 202A to land on the first conveyor belt 214A.

The battery bay <NUM> of the UAV 100B is the same as the battery bay <NUM> of the UAV 100A, but comprises a number of additional features so as to enable ejection of the old battery 202A onto the first conveyor belt 214A, as shown in <FIG>. The battery bay <NUM> is the same as the battery bay <NUM> shown in <FIG>. It is, however, shown as rotated by <NUM> degrees (clockwise in a direction into the page), since this is the orientation of the battery <NUM> when fitted to a rotary type UAV 100B which travels vertically in order to conduct a battery change (rather than horizontally as with fixed-wing UAV 100A).

For the battery bay <NUM> of <FIG>, the column <NUM> supporting the shell <NUM> has been replaced with a support arm <NUM> comprising a number of bends. This enables the battery bay to be suspended from a main body of the UAV 100B at a central location relative to the main body of the UAV 100B, thereby helping to keep the centre of mass of the UAV 100B at a substantially central location. The shell <NUM> also comprises a deflector plate <NUM> and a ramp <NUM>. As the old battery 202A is ejected from the internal space <NUM> defined within the shell <NUM> via the exit <NUM>, the deflector plate <NUM> guides the battery in the direction of the ramp <NUM>. The battery then travels down the ramp under gravity, thereby landing on the first conveyor belt 214A. The deflector plate <NUM> and ramp <NUM> therefore help ensure that, even though the old battery exits the shell <NUM> in a vertical direction, it is guided and deposited under gravity on the conveyor belt 214A. Collection and recharging of the old battery is thus made easier.

The arrangement of <FIG> comprises a resilient member <NUM> supported between two supports 707A and 707B and positioned underneath the new battery 202B. The resilient member is, for example, a resilient web or sheet comprising a hole through which the tapered protrusion <NUM> of the new battery 202B extends so that the exposed portion <NUM> of the flat surface 300A of the new battery 202B is flush with the resilient web or sheet. During the battery exchange operation, the contact between the new battery 202B and the old battery 202A and, subsequently, between the battery bay <NUM> and the resilient member <NUM> causes an impulse to be imparted on the resilient member <NUM>. The impulse causes the resilient member to resiliently deform and, once the new battery 202B is in place in the battery bay <NUM>, to exert an elastic force in an upwards direction on the battery bay <NUM> as the resilient member returns to its original form. This upwards elastic force facilitates the UAV's vertical take-off following its vertical landing to conduct the battery exchange operation.

The battery bay <NUM> of the UAV 100A and 100B may be retractable so that, during normal flight, the battery bay <NUM> is contained within the main body but, as the UAV approaches the new battery 202B, the battery bay <NUM> moves outside of the main body to occupy a position like that shown in <FIG> and <FIG> (the battery bay <NUM> shown in <FIG> and <FIG> is not drawn to scale). This protects the battery and improves the aerodynamic characteristics of the UAV during normal flight. A suitable mechanism may be used be to realise the retractable battery bay. For example, the column <NUM> or support arm <NUM> may be attached to a wall of an internal cavity in the main body of UAV 100A or 100B via a pivot or track with respect to which the column <NUM> or support arm <NUM> is moved by an electric motor and suitable mechanism to retract and expose the battery bay <NUM> (the mechanism is not shown).

Ways of releasably holding the battery <NUM> within the battery bay <NUM> other than through the use of retractable lugs 403A and 403B exemplified in the <FIG> may be used.

In one example, the battery <NUM> is friction fitted within the battery bay <NUM> (that is, held by friction at the points of contact between the battery <NUM> and an internal surface of the shell <NUM>). The retractable lugs 403A and 403B are therefore not required, facilitating easier manufacture of the battery bay <NUM>.

In another example, an internal surface of the shell <NUM> comprises a permanent magnet (not shown) which engages with a ferromagnetic material (e.g. the battery terminal portions 303A and 303B) on a surface 305A-D of the battery <NUM>. The battery <NUM> is thus kept in place in the battery bay <NUM> by the magnetic attraction between the permanent magnet and the ferromagnetic material.

In another example, an internal surface of the shell <NUM> comprises an electromagnet (not shown) which engages with a ferromagnetic material (e.g. the battery terminal portions 303A and 303B) on a surface 305A-D of the battery <NUM>. During normal flight, the electromagnet is activated so that the battery <NUM> is kept in place in the battery bay <NUM> by the magnetic attraction between the electromagnet and the ferromagnetic material. During a battery exchange, the electromagnet is deactivated (or the magnetic strength of the electromagnet is reduced) so as to allow the old battery 202A to leave the battery bay <NUM> and the new battery 202B to enter the battery bay <NUM>. Once the new battery 202B is correctly positioned within the battery bay <NUM>, the electromagnet is reactivated (or the electromagnetic strength is restored) so as to keep the new battery 202B in place. Circuitry (not shown) of the UAV controls the operation of the electromagnet by determining a position of the UAV relative to the battery station <NUM> (e.g. using a Global Navigation Satellite System (GNSS) or beacon signaling between the battery station <NUM> and UAV). The circuitry deactivates the electromagnet (or reduces the electromagnetic strength) when the UAV is within a predetermined distance of the battery station <NUM> and reactivates the electromagnet (or restores the electromagnetic strength) when the UAV is outside a predetermine distance of the battery station <NUM>.

In embodiments, the battery station <NUM> may have a way to impart a relaunch or assistance impulse to the UAV directly after the battery exchange. For example this may be a catapult (for example elastic or mechanical, such as resilient member <NUM>) which is engaged with the structure of the UAV. The engagement of the catapult may take place just as the battery is being exchanged, and controlled in time to release just after battery exchange. In embodiments, this may be a trampoline. It may stretch a membrane as the battery exchange takes place and release directly after battery exchange.

In another example, the retractable lugs 403A and 403B are used but an electric motor (not shown), e.g. a stepper motor, causes the movement of the lugs. During normal flight, the lugs are in an exposed position to engage with the battery <NUM>, thereby keeping the battery <NUM> in place in the battery bay <NUM>. During a battery exchange, the electric motor causes the lugs to retract so as to allow the old battery 202A to leave the battery bay <NUM> and the new battery 202B to enter the battery bay <NUM>. Once the new battery 202B is correctly positioned within the battery bay <NUM>, the electric motor causes the lugs to return to their original position, thereby engaging with the new battery 202B and keeping the new battery 202B in place in the battery bay <NUM>. Circuitry (not shown) of the UAV controls the operation of the electric motor by determining a position of the UAV relative to the battery station <NUM> (e.g. using a Global Navigation Satellite System (GNSS) or beacon signaling between the battery station <NUM> and UAV). The circuitry controls the electric motor to retract the lugs when the UAV is within a predetermined distance of the battery station <NUM> and to restore the lugs to their non-retracted position when the UAV is outside a predetermine distance of the battery station <NUM>.

In another example, a combination of different arrangements is used. For example, retractable lugs which undergo movement with an electric motor are used in combination with a magnet (e.g. a permanent magnet or electromagnet) of an internal surface of the shell <NUM>. This combination works in the same way as the previous paragraph describes, except that a magnetic attraction between the magnet and a ferromagnetic material (e.g. the battery terminal portions 303A and 303B) on a surface 305A-D of the battery <NUM> is maintained throughout the battery exchange procedure to help hold the old battery 202A in place in the battery bay <NUM> until it is pushed out of the battery bay <NUM> by the new battery 202B. This helps ensure that the old battery 202A is ejected from the battery bay at the correct moment (so that it lands on the first conveyor belt 214A rather than in an undesirable place). If an electromagnet is used, this may be deactivated when the lugs are engaged with the battery <NUM>, thereby reducing UAV power consumption.

When an internal surface of the shell <NUM> comprises a magnet (permanent or electromagnet), the magnet may be positioned relative to the internal surface and a surface of the battery <NUM> may comprise a ferromagnetic material (other than the battery terminal portions 305A and 305B) positioned on the battery such that the magnetic attraction between the magnet of the shell <NUM> and the ferromagnetic surface of the battery <NUM> causes the battery to be positioned at a desired position within the shell <NUM>. This facilitates correct positioning of the battery <NUM> in the shell <NUM>. Correct positioning of the battery may be further facilitated by a surface of the battery <NUM> comprising a magnet with north and south poles positioned on the battery such that magnetic attraction between the north (south) pole of the battery magnet and south (north) pole of the shell magnet causes the battery <NUM> to occupy a desired position within the shell. In the previous paragraph's example, correct positioning of the new battery 202B in the battery bay <NUM> helps ensure that the lugs are able to easily engage with the new battery 202B.

Ways of releasably holding the battery on the battery holding portion <NUM> other than through the use of a permanent magnet layer <NUM> may also be used. For example, it will be appreciated that a suitable mechanism using one or more of magnets (permanent or electromagnets), friction or lugs (fixed or mechanically or electrically retractable) may be used in order to hold the new battery 202B in place on the battery holding portion <NUM> until it replaces the old battery 202A in the battery bay <NUM>.

The battery terminal portions 303A and 303B and electrodes 408A and 408B which extend lengthways along the entire length of the battery <NUM> and battery bay <NUM>, respectively, ensure that electrical contact between the battery terminal portions 303A and 303B of at least one of the old and new batteries 202A and 202B and the electrodes 408A and 408B is maintained before, during and after the battery exchange operation. This facilitates continuous battery power supply to the UAV during the battery exchange operation. Alternatively or in addition, the UAV comprises a second battery (not shown) to power the UAV during the battery exchange operation. Circuitry (not shown) of the UAV controls the power supplied by the second battery by determining a position of the UAV relative to the battery station <NUM> (e.g. using a Global Navigation Satellite System (GNSS) or beacon signaling between the battery station <NUM> and UAV). The circuitry controls the second battery to supply power to the UAV instead of the battery held in the battery bay <NUM> when the UAV is within a predetermined distance of the battery station <NUM> and controls the battery held in the battery bay <NUM> to supply power to the UAV instead of the second battery when the UAV is outside a predetermined distance of the battery station <NUM>.

<FIG> exemplify further components of the UAV 100A and system <NUM>, respectively. The UAV 100B may also contain the exemplified components.

The UAV 100A comprises a communication interface <NUM> for performing wireless communication (e.g. radio communication) with the system <NUM> and a storage medium <NUM> for storing digital data (e.g. a hard disk drive, solid state drive, tape drive or the like). Each of these components is controlled by the controller <NUM>. The controller <NUM> comprises the circuitry which performs other operations of the UAV 100A mentioned above.

The system <NUM> comprises a communication interface <NUM> for performing wireless communication (e.g. radio communication) with the UAV 100A, an electric carousel motor <NUM> for rotating the carousel <NUM> (this being mechanically installed at the carousel), one or more electric battery station motors <NUM> for controlling the movement of the support portion <NUM> along the track <NUM>, the rotation of the support portion <NUM> and the rotation of the support shaft <NUM> about the pivot <NUM> (this being mechanically installed at the battery station <NUM>), a battery type detector <NUM> for detecting a type of battery travelling along the conveyor belts 215A and 215B and a storage medium <NUM> for storing digital data (e.g. a hard disk drive, solid state drive, tape drive or the like). Each of these components is controlled by the controller <NUM>. The controller <NUM> is implemented using appropriate circuitry. Although shown together in <FIG>, the components shown in <FIG> are at different spatial locations within the system <NUM> and are housed in appropriate housings (not shown), for example.

The communication interfaces <NUM> and <NUM> allow communication between the UAV 100A and system <NUM>. This communication may comprise the above-mentioned beacon signaling to facilitate the battery exchange operation.

In one example, different types of battery are available to UAVs which make use of the system <NUM>. For example, batteries of different capacity may be available. These are selectable based on scheduling data stored in the storage medium <NUM> of a UAV indicating how far the UAV must travel prior to the next battery change. UAVs travelling a further distance may desire a higher capacity (but heavier weight) battery whereas UAVs travelling a shorter distance may desire a lower capacity (but lighter weight) battery. In another example, different UAVs may require batteries with a different physical shape or different electrical characteristics. Different batteries may be required of provided for operating in different climatic conditions or operating altitudes. This may form part of the scheduling data.

As a UAV approaches the battery station <NUM> in order to conduct a battery exchange operation, the UAV transmits a signal to the system <NUM> indicating the type of battery required by the UAV The signal may carry an identifier for the UAV. Data indicative of the required battery type is stored in the storage medium <NUM> of the UAV. The storage medium <NUM> stores a database. Each charging cavity <NUM> in the carousel <NUM> is identified in the database with the type of battery it contains (or, if empty, a charging cavity <NUM> is identified as empty in the database). Based on the received UAV signal, the controller <NUM> looks up the battery type in the database in order to identify which of the charging cavities comprises the desired battery. The controller <NUM> then controls the carousel motor <NUM> to rotate until the identified charging cavity is positioned such that the battery is removable from the identified charging cavity by the battery station <NUM>. The controller then controls the one or more battery station motors <NUM> to cause the battery station <NUM> to remove the battery from the identified charging cavity and to position the battery ready for the battery exchange operation. The controller <NUM> therefore acts as a selector of the new battery. The signal transmitted by the UAV to the system <NUM> also includes the UAV type (e.g. fixed wing 100A or rotary 100B). Data indicative of the UAV type is stored in the storage medium <NUM> of the UAV. The controller <NUM> therefore controls the one or more battery station motors <NUM> to position the removed battery (which is a new battery 202B) appropriately based on the signal (e.g. if the signal indicates the UAV is fixed wing 100A then the new battery 202B is positioned as shown in <FIG> and if the signal indicates the UAV is rotary 100B then the new battery 202B is positioned as shown in <FIG>).

After the battery exchange operation, the type of the old battery 202A is detected by the battery type detector <NUM>. The battery type detector <NUM> is co-located with the analysis device <NUM>, for example (allowing the battery type detection and battery orientation correction to occur simultaneously). All batteries comprise an identifier which identifies its type. In one example, the battery type detector <NUM> comprises an image sensor and the battery identifier is a Quick Response (QR) code readable by the image sensor. In another example, the battery type detector <NUM> comprises a radio frequency identity device (RFID) detector and the battery identifier is an RFID tag. It is appreciated that other identification methods may be used. The controller <NUM> then identifies an empty charging cavity <NUM> using the database of the storage medium <NUM> and controls the carousel motor <NUM> to rotate until the empty charging cavity is positioned such that the old battery 202A drops into the empty charging cavity under gravity for charging when it reaches the end of the second conveyor belt 215B. A charging cavity becomes empty when the battery station <NUM> removes a battery from the charging cavity for the removed battery to be a new battery 202B in a battery exchange operation. Each charging cavity comprises a sensor (not shown) which sends a signal to the controller <NUM> when a battery is removed from the charging cavity, for example. The controller <NUM> then identifies the charging cavity as empty in the database of the storage medium <NUM> in response to this signal.

The controller <NUM> may receive a signal from the electrodes <NUM> of the analysis device <NUM> indicating the measured voltage of an ejected battery 202A. The voltage of the ejected battery is related to the remaining battery power. The controller <NUM> compares the measured voltage of the battery to data stored in the storage medium <NUM> indicating the relationship between the measured voltage and remaining battery power for the battery type (known from the battery type detector <NUM>). If the measured voltage is below a predetermined threshold, it is confirmed that the remaining battery power is sufficiently low that it was appropriate for the UAV to conduct the battery exchange operation. If the measured voltage is above the predetermined threshold, it is confirmed that the remaining battery power is not sufficiently low that it was appropriate for the UAV to conduct the battery exchange operation. Here, there may be a fault with the UAV because it conducted a battery exchange operation due to having a low battery even though this wasn't the case. The system <NUM> therefore transmits a signal to the UAV informing the UAV of a potential fault. The UAV may therefore visit a maintenance station (not shown) to be checked and serviced / repaired if necessary.

The UAV may exchange a battery for reasons other than a low battery. For example, whilst flying, the UAV may receive a scheduling signal from a base station (not shown) commanding the UAV to undertake a longer distance journey than is possible with the UAV's current battery (e.g. if the UAV is carrying a standard capacity battery for journeys of a standard distance instead of a high capacity battery for journeys of an extended distance). When approaching the battery station <NUM> for a battery exchange, the UAV may transmit a signal to the battery station <NUM> indicating the reason for the battery change (e.g. low power, higher capacity battery needed or the like). The signal identifies the UAV and the battery (each battery having an identifier unique to the battery as well as having a battery type identifier - the unique battery identifier may be provided with the battery type identifier for detection by the battery type detector <NUM>, for example). The information indicated by the signal is stored in a database in the storage medium <NUM> (e.g. in the form UAV ID: X, battery ID: Y, reason: Z). When the analysis device <NUM> measures the voltage of battery Y, the controller <NUM> looks up "battery ID: Y" in the database and determines the UAV ("X") and reason ("Z"). If the reason Z is that the battery power was low but the measured voltage of the analysis device <NUM> indicates that the battery power is not low, then the controller <NUM> determines that there is a fault with the UAV and controls the communication interface <NUM> to transmit a signal to the UAV indicating the fault. On the other hand, if the reason Z is that a higher capacity battery is required, then even if the measured voltage of the analysis device is not low, the controller <NUM> knows that this is not the reason for the battery exchange and that there is no fault with the UAV.

The UAV may transmit a signal indicating any type of measurable data about a battery to be replaced as it approaches the battery station <NUM> for a battery exchange. The controller <NUM> may then measure the same data using analysis device <NUM> and compared it to the received data. This helps to ensure the battery monitoring systems of the UAV are working correctly and allows the UAV to be alerted if a problem is detected.

The battery <NUM> can have a different number of sets of terminals 303A and 303B than the four sets (one set on each surface 305A-D) shown in <FIG>. For example, only one set of terminals may be used. In order to facilitate electrical contact between the one set of terminals 303A and 303B and the charging contacts 227A and 227B during charging and between the terminals 303A and 303B and electrodes 408A and 408B when the battery is installed in the UAV, the system <NUM> comprises a further battery orientation device (not shown) for orientating the battery so that the terminals 303A and 303B are on the top surface of the battery when it is placed on the second conveyor belt 215B. This facilitates correct orientation of the one set of battery terminals 303A and 303B when the battery enters the charging cavity and when it is removed from the charging cavity by the battery holding portion for placement in the battery bay <NUM> of the UAV.

The described embodiments are examples of how the present disclosure may be implemented.

The disclosure may be used in conjunction with a subscription charge system for battery exchange. A fixed charge may be levied for example for a number of exchanges. The controller <NUM> may verify the authenticity of batteries that are exchanged. If an unauthorised battery is exchanged, penalties may be levied. There may be a fixed subscription charge (standing charge) and a charge per battery exchange. The subscriber may be identified by the UAV which has an electronic or visual identifier or by the battery that is exchanged or both. The electronic identifier may be transmitted wirelessly. The controller <NUM> at the battery exchange system (for example system <NUM>) may communicate with a subscription server over a computer network (using communication interface <NUM>). The subscription server contains information on each subscription held and controls billing for battery exchanges and can control whether an exchange is permitted or occurs.

Claim 1:
A system comprising an unmanned aerial vehicle (100A), UAV, comprising a battery holding portion (<NUM>) configured to releasably hold a first battery (202A) to provide electrical power to the UAV, the first battery and a second battery (202B),
wherein the battery holding portion is configured to hold the first battery such that, upon the UAV encountering the second battery (202B) positioned in the path of flight travel of the UAV, the first battery receives a mechanical impulse from the second battery and is released from the battery holding portion due to the mechanical impulse, and such that the second battery replaces the first battery to become held by the battery holding portion to provide electrical power to the UAV.