GB2540052A

GB2540052A - Charging and re-provisioning station for electric and hybrid unmanned aerial vechicles

Info

Publication number: GB2540052A
Application number: GB1613113.8A
Authority: GB
Inventors: Brotherton-Ratcliffe David
Original assignee: Neva Aerospace Ltd
Current assignee: Neva Aerospace Ltd
Priority date: 2014-05-30
Filing date: 2015-06-01
Publication date: 2017-01-04
Anticipated expiration: 2035-06-01
Also published as: GB2551055A; GB201613113D0; GB2540052B; GB2529021B; GB2551055B; GB201509401D0; GB2529021A; GB201409654D0; DE202015102833U1; GB201709156D0

Abstract

A charging station for one of more electric VTOL aircraft 105,106 comprises a support pole 101 or frame and a landing pad 104 attached to the support pole or frame. The charging station further comprises a charging system connected to a power source for recharging and monitoring the batteries of the aircraft 105,106. A precision docking and anchoring system to guide the aircraft 105,106 into docking on the landing pad 104 and to hold the aircraft 105,106 in a stable position whilst charging is also included. An electrical connection system automatically provides an electrical connection between the aircraft 105,106 and the station after landing. A communication system provides a communication between the charging station and a central control station and between the drone and the charging station. A precision positioning system includes a differential GPS ground station. A re-provisioning station for VTOL UAVs may include unloading and loading systems for replacing one or more battery packs. Battery swapping may be carried out automatically.

Description

CHARGING AND RE-PROVISIONING STATION FOR ELECTRIC AND HYBRID

UNMANNED AERIAL VECHICLES

FIELD OF THE INVENTION

The present invention relates to electric and electric-hybrid aircraft with VTOL (vertical take-off and landing) capability and in particular to the design of charging and reprovisioning stations for the vehicles.

BACKGROUND TO THE INVENTION

Electric and hybrid unmanned vehicles or drones based on a multi-rotor concept can be made to exhibit extremely stable VTOL flight. This makes such drones potentially attractive for a variety of uses including the surveillance of oil and gas pipelines or the periodic inspection of railway lines and roads. In the case of all-electric vehicles current battery technology limits the useful range of the vehicle to usually around 10 km. Although hybrid aircraft can be made to serve rather greater distances, their complexity constitutes a disadvantage. Other methods of increasing range such as including an aerofoil into the design of a multi-rotor unmanned aerial vehicles (“UAVs”) also increase complexity. Ultimately, the restricted range of electric and hybrid UAVs constitutes a major impediment to the uptake of this technology in surveillance and other industries.

Charging stations are known as a potential solution to the restricted range problem of electric multi-rotor aircraft. Reference is made, for example, to “Automated Recharging For Persistence Missions With Multiple Micro Aerial Vehicles” by Yash Mulgaonkar, a thesis in robotics presented to the Faculties of the University of Pennsylvania in partial fulfilment of the requirements for the Degree of Master of Science in Engineering, 2012 (the contents of which are incorporated herein by reference). However, such discussions have to date concentrated on the development of essentially laboratory prototypes based on exposed charging conductors using contact charging. Whilst these devices have demonstrated integrated flight times of up to nearly ten hours, such simplistic systems remain fundamentally impractical for commercial exploitation in realistic external environments where the problems of rain, wind, snow and ice must be dealt with in addition to the problems of animal interference, human safety and asset protection.

It is therefore desired to provide an improved an improved charging station.

SUMMARY OF THE INVENTION

According to an aspect of the present invention there is provided a charging station for one of more electric VTOL aircraft comprising: a support pole or frame; a landing pad attached to the support pole or frame; a charging system connected to a power source for recharging and monitoring the batteries of the aircraft; a precision docking and anchoring system to guide the aircraft into docking on a ianding pad and to hoid the aircraft in a stabie position whiist charging; an eiectricai connection system; a communication system; and a precision positioning system; wherein: the electrical connection system automatically provides an electrical connection between the aircraft and the charging station after landing; the communication system provides a communication between the charging station and a central control station and between the aircraft or drone and the charging station; and the precision positioning system includes a differential GPS ground station.

The landing pad is preferably attached to the top of the pole or frame.

The power source preferably comprises solar panels and a regulation unit.

The power source may comprise a wind turbine and a regulation unit.

The power source may comprise a generator that uses fuel to create electricity. The power source preferably comprises mains electricity.

The landing pad is preferably at least 5 metres high, further preferably at least 10 metres high.

The precision anchoring system is preferably based on magnetic attraction between the aircrafts legs and slots cut into or provided in the landing pad.

The electrical connection system is preferably based on a servo operated connection plug which automatically inserts and de-inserts itself into one or both of the legs of the aircraft.

The communication system is preferably based on or comprises a microwave or RF link.

The communication system may be based on or comprises a satellite link.

The communication system may be based on or comprises a cabled link.

The charging station preferably further comprises a de-icing system to melt snow and ice accumulating on the landing pad.

According to another aspect of the present invention there is provided a charging station for a plurality of electric VTOL aircraft comprising: a support poles or frame; a plurality of landing pads attached to the support pole or frame or arms attached to the support pole or frame; a charging system connected to a power source for recharging and monitoring the batteries of the aircraft; a precision docking and anchoring system to guide each the aircraft into docking on the plurality of landing pads and to hold each the electric VTOL aircraft in a stable position whilst charging; an electrical connection system; a communication system; and a precision positioning system; wherein: the electrical connection system automatically provides an electrical connection between the aircraft and the charging station after landing; the communication system provides a communication between the charging station and a central control station and between the aircraft or drone and the charging station; and the precision positioning system includes a differential GPS ground station.

The power source preferably comprises solar panels and a regulation unit.

The power source may comprise a wind turbine and a regulation unit.

The power source may comprise a generator that uses fuel to create electricity. The power source may comprise mains electricity.

The charging station preferably further comprises a de-icing system to melt snow and ice accumulating on each landing pad.

The charging station preferably further comprises a retractable weather protection system consisting of three or more panels which can be automatically moved so as to provide an enclosure for an aircraft whilst docked.

The charging station preferably further comprises a plurality of retractable weather protection systems each consisting of three or more panels which can be automatically moved so as to provide an enclosure for all aircraft whilst docked.

According to another aspect there is provided a battery swapping station for one of more electric VTOL aircraft comprising: a support pole or frame; a landing pad attached to the support pole or frame; a charging system connected to a power source for recharging and monitoring offloaded aircraft battery packs; a precision docking and anchoring system to guide the aircraft into docking on the landing pad and to hold the aircraft in a stable position whilst docked; a loading and unloading system for battery packs; a communication system; and a precision positioning system; wherein: the communication system provides a communication between the charging station and a central control station and between the aircraft or drone and the charging station; the loading and unloading system provides a means to automatically unload a battery from an aircraft and to replace it by a newly charged battery; and the precision positioning system includes a differential GPS ground station. According to another aspect there is provided a battery swapping station for one of more electric VTOL aircraft comprising: a support pole or frame; a plurality of landing pads attached to the support pole or frame or to an arm attached to the support pole or frame; a charging system connected to a power source for recharging and monitoring offloaded aircraft battery packs; a precision docking and anchoring system to guide the aircraft into docking on the landing pad and to hold the aircraft in a stable position whilst docked; a plurality of loading and unloading systems for battery packs; a communication system; and a precision positioning system; wherein: the communication system provides a communication between the charging station and a central control station and between each aircraft or drone and the charging station; the loading and unloading system provides a means to automatically unload a battery from an aircraft and to replace it by a newly charged battery; and the precision positioning system includes a differential GPS ground station.

The source of power is preferably derived from any of: (i) solar power; (ii) wind power; (iii) mains; or (iv) a generator.

The charging station or battery swapping station preferably further comprises a series of sound baffles to attenuate the noise of landing and departing aircraft.

The charging station or battery swapping station preferably further comprising a system for refilling the fuel tanks of a hybrid aircraft.

The charging station or battery swapping station preferably further comprises a system for refilling one or more agricultural tanks, chemical tanks, water tanks, gas tanks or liquid tanks of an aircraft.

The charging station or battery swapping station preferably further comprises an automatic system for loading or unloading cargo from an aircraft.

The charging station or battery swapping station may be arranged such that the central pole or frame accommodates an access system allowing human access for loading and unloading cargo and/or passengers to and from docked aircraft.

The charging station or battery swapping station may be arranged such that the station is located in the sea and a wave or water current generator is used to generate power for the station.

The charging station or battery swapping station may be arranged such that the central support pole or frame is replaced by an airship and the landing pads are mounted directly on the top of the airship.

According to an aspect of the present invention there is provided a method of recharging one of more electric VTOL aircraft comprising: guiding an electric VTOL aircraft into docking on a landing pad and holding the aircraft in a stable position whilst charging; automatically providing an electrical connection between the electric VTOL aircraft and a charging station after the electric VTOL aircraft lands on the landing pad; providing a communication between a charging station and a central control station; and providing a communication between the electric VTOL aircraft and the charging station.

According to an aspect there is provided a method of recharging a plurality of electric VTOL aircraft comprising: guiding the plurality of electric VTOL aircraft into docking on a plurality of landing pads and holding each the electric VTOL aircraft in a stable position whilst charging; automatically providing an electrical connection between each the electric VTOL aircraft and a charging station after the plurality of electric VTOL aircraft land on the landing pads; providing a communication between a charging station and a central control station; and providing a communication between the plurality of electric VTOL aircraft and the charging station.

According to an aspect there is provided a method of swapping a battery of one of more electric VTOL aircraft comprising: guiding an electric VTOL aircraft into docking on a landing pad and holding the electric VTOL aircraft in a stable position whilst docked; automatically unloading a battery from the electric VTOL aircraft and replacing the battery with a charged battery; providing a communication between a charging station and a central control station; and providing a communication between the electric VTOL aircraft and the charging station.

According to an aspect there is provided a method of swapping a battery of a plurality of electric VTOL aircraft comprising: guiding the plurality of electric VTOL aircraft into docking on a plurality of landing pads and holding each electric VTOL aircraft in a stable position whilst docked; automatically unloading a battery from each of the plurality of electric VTOL aircraft and replacing each battery with a charged battery; providing a communication between a charging station and a central control station; and providing a communication between the plurality of electric VTOL aircraft and the charging station.

According to an aspect there is provided a charging station for one or more electric VTOL aircraft comprising: one or more landing pads; a charging system for recharging one or more batteries of an electric VTOL aircraft; and an automatic electrical connection system arranged and adapted to automatically provide an electrical connection between one or more electric VTOL aircraft when landed, in use, on the one or more landing pads and the charging system.

The automatic electrical connection system preferably comprises one or more motors and wherein the automatic electrical connection system is preferably arranged and adapted to actuate the one or more motors so as to drive one or more connectors, sockets or plugs into electrical contact, in use, with one or more corresponding connectors, sockets or plugs of the electric VTOL aircraft.

According to an aspect there is provided a battery swapping station for one of more electric VTOL aircraft comprising: one or more landing pads; and an unloading and loading system for automatically replacing one or more battery packs of one or more electric VTOL aircraft when landed on the one or more landing pads with one or more at least partially charged or fully charged battery packs.

According to an aspect there is provided a method of recharging one or more electric VTOL aircraft comprising: automatically providing an electrical connection between one or more electric VTOL aircraft when landed on one or more landing pads and a charging system in order to recharge one or more batteries of the one or more electric VTOL aircraft.

The method preferably further comprises actuating one or more motors so as to drive one or more connectors, sockets or plugs into electrical contact with one or more corresponding connectors, sockets or plugs of the one or more electric VTOL aircraft.

According to an aspect there is provided a method of swapping a battery of one or more electric VTOL aircraft comprising: automatically replacing one or more battery packs from one or more electric VTOL aircraft when landed on one or more landing pads with one or more at least partially charged or fully charged battery packs.

The preferred embodiment relates to a network of charging and re-provisioning stations for small to medium-sized electric or hybrid aircraft having precision VTOL capability. In general each charging station consists of a tall pole or frame on top of which is placed a landing pad for one or more aircraft, one or more anchoring systems for clamping each aircraft to the pad, an electric charging system to recharge each aircraft’s batteries based on a secure plug and socket system, a re-provisioning system for refuelling or renewing liquid or gas payloads, a precision positioning system allowing the aircraft to land and take-off with the required precision and a communication system for communication with a central control station. Optionally solar panels or wind turbines may be included in the design to provide power autonomy of the station. In addition, when such stations are located in the sea, wave turbines may be included for the production of power. In colder climates an electromechanical opening roof and cover system may be used to protect the landing pad from ice and snow build-up. According to another embodiment a de-icing system may be used to keep the landing pad unencumbered.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings in which:

Fig. 1 shows a charging station according to a preferred embodiment; and

Fig. 2 shows detail of a docking, clamping and electrical connection system of the landing pad according to a preferred embodiment.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Fig. 1 shows a charging station for one or more electric VTOL aircraft according to a preferred embodiment of the present invention. A 8 m long steel pole 101 is preferably mounted securely in concrete in the ground 102. A barbed-wire fence 103 may be provided to stop vandals from climbing the pole. An aluminium and plastic landing pad 104 measuring 1.5 m x 3 m is preferably mounted on top of the pole 101. The platform is preferably designed to accommodate two small “Ceres-A” drones (Neva Aerospace Ltd) 105,106 which are preferably each equipped with 5 MJ Li-polymer battery packs and battery charging and communications ports at the ends of each of the skids.

Ceres-A drones utilise four 17” (42.5 cm) ducted fans each incorporating two counter-rotating propellers arranged in a quad-configuration. The drones have a size of approximately 1 metre in diameter and a weight with payload of approximately 20 kg. The empty weight is 14 kg. Flight endurance is just over 25 mins with a maximum range of 15 km.

An electronics bay 107 is preferably located just under the landing pad 104. The electronics bay 107 preferably comprises charging circuits for the two battery charging and monitoring systems of the landing pad, telecommunications electronics, a differential GPS ground station system, regulation and power supply electronics for conversion of power from solar cells and a lithium-ion battery energy storage system capable of storing 25 MJ of electrical energy.

Two solar panels 108,109 are preferably installed on the charging station, each 2 m X 2 m. The solar panels continuously charge the lithium-ion storage batteries of the station. Under good solar conditions, the station’s batteries can be charged several times per day allowing up to 5-10 recharges of the Ceres-A battery packs. A telecommunications dish 110 is preferably provided and preferably ensures communication with a central control station. A microwave antennae (not shown) for communication between the drone and the station may also be provided.

Fig. 2(a) shows a detailed plan view of a preferred landing pad 104,201 and Figs. 2(b) and (c) show corresponding side views. Four rectangular slots 202-205 having dimensions of 110 cm x 6 cm x 6 cm are preferably cut into an aluminium plate 201. Pairs of these slots are designed to receive the twin landing skids 209,210 of a Ceres-A drone 208 (having four ducted fans 211-214). Drainage holes 219 may be provided to evacuate water during precipitation. The skids of the Ceres-A are 80 cm long thereby leaving 30 cm of longitudinal leeway on landing.

Four triangular plastic guides 206,207 may be provided around each slot to guide the landing skids 209,210 into the slots 202-205 both longitudinally and laterally. A differential GPS ground station is preferably incorporated into the station in conjunction with the GPS system on-board the Ceres-A drone so as to allow a position determination accuracy of around 1 cm on landing. This is aided by sonar sensing aboard the Ceres-A which produces millimetre accurate height readings. An auto-landing program in the flight controller of the Ceres-A is able to land the drone to an accuracy of usually +/-3 cm depending on wind conditions. The guides 206,207 act to locate the skids 209,210 properly in the slots 202-205. Electromagnets at the base of each slot 202-205 are preferably activated on landing and clamp the drone’s skids in a fixed position within the slots. Connectors 216,218 are then preferably driven into corresponding electrical sockets in the Ceres’ skids 209,210 by servo-motors 215,217 each driving a threaded rod. Two electrical connections are required for charging and a further RS485 connection and CAN BUS connection are provided for communications between the drone and the station. A series of embedded heating coils within the landing pad may be used to ensure di-icing and the melting of snow. The resultant water may be evacuated through drainage holes 219.

The station is preferably controlled by a Raspberry Pi microcomputer which provides all the interfaces required for automatic charging, communications between the docked or approaching/departing drones and between a remote central control station. In general the station broadcasts to the central control station its status every 10 seconds by satellite or microwave link. This status may comprise of: (a) the serial number of the drone in docking station A (if no drone is present then a serial number 000-000 may be utilised); (b) the serial number of the drone in docking station B (if no drone is present then a serial number 000-000 may be utilised); (c) the energy in the batteries of the drone in docking station A in kJ; (d) the energy in the batteries of the drone in docking station B in kJ; (e) the energy remaining in the energy storage system of the charging station in kJ; (f) the wind speed in knots and direction in bearing from North in degrees at landing pad; (g) the scheduled take-off time for the drone in docking station A; (h) the scheduled take-off time for the drone in docking station B; (i) the scheduled landing time for a drone into docking station A; and 0 the scheduled landing time for a drone into docking station B.

Communication is preferably effected by RS485 from the Raspberry Pi to the transmitter unit. Communication between the Raspberry Pi and the charging unit controllers, the magnetic clamping and motorised connection system controller, the wind vector measurer and the de-icing controller is preferably via serial peripheral interface (“SPI”).

The Raspberry Pi also preferably communicates directly with each docked drone via RS485 every two seconds to confirm the status of docking (docked = 1, undocking or docking = 2, undocked = 3) and the status of charging (charging = 1, not charging = 0).

The flight controller of the Ceres-A is preferably programmed only to take-off when it is undocked.

The Raspberry Pi listens to the central control station for commands. The commands may include: (A) drone in docking station A, take-off at time XX hrs XX mins XX seconds; (B) drone in docking station B, take-off at time XX hrs XX mins XX seconds; (C) upload flight plan to drone in docking station A; (D) upload flight plan to drone in docking station drone B; (E) download data from drone in docking station A; (F) download data from drone in docking station B; (G) prepare to receive drone serial number XXX-XXX for landing at time XX hrs XX mins XX seconds into docking station X; (H) abort command associated with drone in docking Station A; and (I) abort command associated with drone in docking station B.

On receipt of one of these commands the Raspberry Pi will preferably check validity. For example, if the microprocessor receives a command for the drone at docking station A to take-off at a certain time, the microprocessor will check first whether in fact there is actually a drone in docking station A. If this test is passed then the microprocessor will then preferably communicate to the drone in this docking station to see whether a viable flight-plan exists in the drone’s navigation system. If again this test is passed, then the Raspberry Pi will preferably confirm to the central control station that it has accepted the command for take-off and the take-off time will then figure in the regular status messages broadcast by the Raspberry Pi.

When a type G command is received the Raspberry Pi will preferably accept it if the time of landing is more than three minutes in the future, if the docking station is free, if the drone’s serial number matches one of a list of authorised drones stored in its memory and if the wind speed is not past a critical set-point. At three minutes to landing the Raspberry Pi will attempt to initiate microwave communications with the drone in question using the communications protocol stored in its memory corresponding to the drone’s serial number. If no communication can be made successfully after a further one minute, the Raspberry Pi will send a message to the central station informing it that it cannot reach the drone. At the same time the request for landing will be aborted. On the other hand if communication is established with the drone, the Raspberry Pi will preferably send a command recognised by the on-board flight controller to land. On confirmation the microprocessor will then send GPS ground station signals to the on-board flight controller of the drone 10 times per second, enabling the drone to calculate the landing target position to within 1 cm. The station will also preferably send atmospheric pressure measurement to the drone as measured by its barometer immediately after the land command. This enables the Ceres-A drone 208 to get an accurate relative height fix to the landing pad using its on-board MS5611-01BA altimeter. A program in the flight controller of the drone then preferably lands the drone automatically. At 2 m height to the landing pad the Ceres’ sonar system is preferably used to improve the height fix accuracy. In general different auto-land programs can be uploaded into the Ceres flight controller depending on the type of landing required. These can be used to produce slow or fast landings, to optimise landing in high wind or gusting conditions, to optimise energy consumption on landing or to minimise noise pollution.

It will be clear to someone skilled in the art that various different types of mechanical docking and connection systems may be envisioned in a station. For example, a robotic arm system may be used which identifies the drone, holds it after landing and then moves it to an exact location after which a connector is inserted to charge the drone.

Communications between the drone and the station can also be via wireless internet, RF or cabled connection. Battery charging may also be via electromagnetic induction. In this case a drone are arranged to land on the pad and are then preferably clamped by electromagnetic attraction or air (vacuum) pressure. The drone may then be charged inductively. According to this embodiment the landing pad may be made from an insulating material so as to reduce induced ohmic losses and the induction coils may be moved (two-dimensionally) to maximise the inductive coupling. This allows a smaller landing precision for the drone. The drone may be positioned to maximise the inductive coupling.

Battery swapping station

According to another embodiment the charging station may comprise a battery pack swapping station. According to this embodiment a similar station to that described above may be used with the exception that when a drone lands on the pad, its battery pack is preferably automatically swapped for a fully charged battery pack from the station. This allows a drone to land and quickly take-off again without having to wait for its batteries to be recharged by the station. A number of battery packs (for example 10-20) may be kept in a cartridge system under the landing pad permitting many drones to land and pick-up new batteries from the station. The old batteries may then be inserted into the end of the cartridge and recharged in a similar manner according to the preferred embodiment as described above. According to this embodiment battery systems from the drone are dismounted automatically and the dismounted battery is automatically inserted into a cartridge system. A charged battery from the other end of the cartridge system is then automatically mounted.

Another method of swapping batteries is by swapping the electrolyte of certain battery systems. This constitutes a simpler version of the battery swapping station as fluid may more easily be pumped from the drone to the station and vice-versa. The discharged electrolyte is then preferably charged in one of a plurality of electro-chemical charging cells in the station.

Battery charging and refuelling station

For hybrid drones fuel can be pumped aboard from one or more reservoirs in the station in addition to the charging or swapping of batteries.

Battery charging and re-provisioning station

Drones may require chemical products for their missions in addition to resupply of fuel and electrical recharging. For example, agricultural drones may require pesticides and fertilisers. The chemical products may be in the form of gas, powder or liquid. These products may be conveniently stored in a station and pumped aboard the drone when docked.

Mounting locations

Recharging, refuelling and re-provisioning stations may be located virtually anyway. The most common location is on land. However, mounting on the sea bed in shallower waters is also possible. In addition installation on a boat or airship is also possible. In the case of an airship the shape of the airship may be topologically annular and the landing pad may be placed in the bottom centre of the annulus without a pole. This allows wind protection during landing and affords good stability of the airship as long as the landing pad is sufficiently low.

Power supply

The power supply for a station may, as in the preferred embodiment, come from solar radiation. However, wind turbines may also be used. In addition generators burning any type of fuel are also possible sources of power. Mains power may also be utilised.

Communications

Communication to the central control station can be via land-line, microwave link, satellite link, telecoms link, laser link or general RF link. Communication between the station and the drone may be via microwave, general RF or laser.

Camera monitoring of stations

For security and other reasons one or more cameras may be attached to the station for monitoring the drones, the station and the surrounding land. Pictures may be broadcast to the central control station.

Combination of charging stations with telecoms and mobile telephone stations

Charging stations may also be built to include telecoms and mobile telephone transceiving equipment. Alternatively, existing telecoms towers may be modified to host a charging station for drones.

Weather protection

In colder and more hostile climates snow and precipitation can cause major problems. In particular snow and ice can accumulate on the drones themselves while docked and it may become difficult or impossible for the station’s de-icing system to cope. As a result drones may become stranded and the station rendered inoperational. To counter this problem, servo or hydraulically operated doors may be included in the design of a station. For example, large triangular shaped panels may be included in the preferred embodiment which hinge along the edges of the landing pad. These panels may be controlled by hydraulic pistons which act to open and close them. In the fully open state the panels may resemble the petals of a flower with the landing pad being in the centre. In the fully closed position the petals are closed forming a large triangular enclosure around the two docking stations. This system not only protects the drones whilst docked but also acts to make landings easier in high wind conditions by acting as a wind block. The design also helps to mitigate noise pollution.

Other precision landing systems

According to the preferred embodiment differential GPS, in combination with accurate barometric altimeters and sonar, is preferably used to define a landing target with a precision of around 1 cm in all directions. It will be understood by someone skilled in the art that other forms of precision positioning systems can be used for this purpose. For example, a visual target on the pad may indicate the landing spot and a camera on the drone may then use an image processor to identify the target. Alternatively, radiofrequency or laser beacons may be used. In addition laser, sonar or RF radar mounted on the station may be used to identify the drone’s position and this position may then be communicated to the drone.

Station unserviceable or compromised

It may happen that a station becomes unserviceable immediately prior to landing. This situation could arise due to a natural accident, vandalism or other cause. In the case that an approaching drone has insufficient battery power on board, the drone can be programmed to make a safe landing on the ground in a location transmitted to it by the station as constituting a safe landing spot or alternatively this location can be carried in the memory of the drone’s flight controller.

Stations for different numbers of drones

Various further embodiments are contemplated comprises many types of charging or swapping stations. According to the preferred embodiment two docking stations enable two drones to be charged at a time. However, stations comprising only a single docking station may also be constructed. For some applications such stations may be best placed close to the ground for access. However, the landing pad should preferably be located relatively high so as to maximise safety and reduce noise pollution. In some cases many landing pads may be required in a single station and in this case arms may be constructed off the main frame or pole, each carrying one or more landing pads. In addition an automatic system may be used to move and stack small drones once they have landed on a given pad. According to an embodiment pads may be moved automatically so that takeoff and landing only happens when a pad is at the top, but pads can be stored with their drones under this top position. Stations may be relatively small or relatively large. In general they may accommodate a single drone or a plurality of drones. The drones may also be relatively small or relatively large. In the larger limit the stations may accommodate manned vehicles or drones carrying passengers. In this case the interior of the main support pole or frame may contain stairs, ladders or an elevator system. This is also true for large drone stations taking heavy supplies from station to station. The interior of the pole or frame may then be used as access for loading and unloading drones. In some sense the large drone station may functionally resemble a small cable car station.

Noise abatement

One of the problems of larger drones is the noise pollution created on the ground. By using stations built on tall poles or frames this noise pollution can be considerably reduced. However, further measures may be taken to reduce noise. These consist of the installation of noise reflecting and absorbing baffles just under the landing pad. In addition the use of ducted fans rather than free fans in multi-rotor aircraft can significantly reduce noise.

Applications and rationale

Electric and hybrid multi-rotor drones provide highly stable and versatile flight platforms capable of precision VTOL manoeuvres. However, they are limited today to a flight endurance of usually less than 30 minutes due to the limitations of current battery technology. This limitation drastically curtails the usefulness of the multi-rotor drone. The use of a network of robust commercial charging stations however changes this equation and opens up many applications. For example, charging stations may be placed every 10 km next to a railway line permitting real-time constant surveillance of the line by small drones. Likewise the technology may be used with oil and gas pipelines.

In mountainous and remote regions a 2-dimensional network of stations may provide a permanent monitoring facility enabling instant remote monitoring of people, wildlife, fires, earthquakes or volcanoes over many thousands of square kilometres. On coastlines a linear network of stations could provide a constant monitoring service for national coastline protection. On beaches the technology may be used for spotting sharks and other dangers. By careful positioning of the stations, either off-shore or inland, small drones may be essentially inaudible to people on the ground and by maintaining sufficient altitude during flight they could also be hard to spot visually.

Charging stations may also be incorporated into electric pylons or poles used for the supply of electricity or telecoms. A possible application of drones would be for the maintenance, monitoring and repair of these networks.

Precision agriculture also requires charging stations for a proper automation of this process. Transport of critical supplies by drones in mountains and remote areas would also be targets. Larger drones may be used in search and rescue missions or for the transport of critical items or even wounded people.

Many applications which could benefit from the use of such charging stations are situated in hot countries and have abundant access to solar power. This makes the entire process energy-free and clean if solar panels are used. By installing the landing pads high up, there is no human access to dangerous rotor blades and noise pollution is reduced significantly. Since all of the assets are essentially mounted at the top of a tall pole or frame, there is also a much smaller risk of human or animal interference.

Although the present invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the scope of the invention as set forth in the accompanying claims.

Claims

1. A charging station for one or more electric VTOL aircraft comprising: one or more landing pads; a charging system for recharging one or more batteries of an electric VTOL aircraft; and an automatic electrical connection system arranged and adapted to automatically provide an electrical connection between one or more electric VTOL aircraft when landed, in use, on said one or more landing pads and said charging system.

2. A charging station as claimed in claim 1, wherein said automatic electrical connection system comprises one or more motors and wherein said automatic electrical connection system is arranged and adapted to actuate said one or more motors so as to drive one or more connectors, sockets or plugs into electrical contact, in use, with one or more corresponding connectors, sockets or plugs of an electric VTOL aircraft.

3. A battery swapping station for one of more electric VTOL aircraft comprising: one or more landing pads; and an unloading and loading system for automatically replacing one or more battery packs of one or more electric VTOL aircraft when landed on said one or more landing pads with one or more at least partially charged or fully charged battery packs.

4. A method of recharging one or more electric VTOL aircraft comprising: automatically providing an electrical connection between one or more electric VTOL aircraft when landed on one or more landing pads and a charging system in order to recharge one or more batteries of said one or more electric VTOL aircraft.

5. A method as claimed in claim 4, further comprising actuating one or more motors so as to drive one or more connectors, sockets or plugs into electrical contact with one or more corresponding connectors, sockets or plugs of said one or more electric VTOL aircraft.

6. A method of swapping a battery of one or more electric VTOL aircraft comprising: automatically replacing one or more battery packs from one or more electric VTOL aircraft when landed on one or more landing pads with one or more at least partially charged or fully charged battery packs.