TECHNICAL FIELD

The present invention relates to a system and method for automatic launching and landing UAVs (Unmanned Aerial Vehicles), wherein a ground station is adapted for automatic UAV launching and landing.

BACKGROUND ART

There are known in the art systems for launching and/or capturing an unmanned aerial vehicle (UAV).

In US 2006/0249623 a launch/capture platform is described including a frame, a floor attached to the frame and capable of supporting the UAV, and means for acquiring and tracking the UAV in flight. The platform is controllable to perform a motion in response to position and attitude of an approaching UAV. Further, means are provided for launching the UAV from the platform and for capturing an in-flight UAV to the platform.

SUMMARY OF THE INVENTION

One object of the present invention is to provide an improved launching/landing platform.

This has in one example been achieved by means of a system for automatic launching and landing UAVs (Unmanned Aerial Vehicles) comprising a ground station adapted for automatic UAV launching and landing. The ground station is not necessarily placed on the ground. It can for example be placed at the deck of a ship. The important thing is that the ground station acts as a base for launching and landing UAVs. The ground station comprises means for communication with UAVs present within a range from the ground station, an arrangement adapted for launching UAVs and for capturing in-flight UAVs, said arrangement having at least one controllable arm, a computing unit arranged to compute a meeting point between the at least one controllable arm and one in-flight UAV based on data communicated between the UAV and the ground station by means of said means for communication, and a control unit arranged to control the at least one arm to capture an in-flight UAV at the meeting point or to launch one UAV, wherein the control unit is arranged to control the at least one arm to move a UAV between the meeting point and at least one storage position.

There are many advantages with the system above. Some of them are listed below.

For example, no or a minimum of personnel resources are required to operate the ground station. No manual steps are required to store away a captured UAV and to fetch a UAV for launch.

Further, the ground station can be made portable or movable, for example placed on a truck platform or at the deck of a ship. Thereby, the ground station can be transported to any suitable location and a UAV can be launched and landed at short notice.

No or a minimum of infrastructure is required in addition to the ground station. Thereby, the ground station can be positioned freely without the need to consider available infrastructure. Further, UAVs with low weight/force ratio can be launched and landed. This enables the use of UAVs which would be unfeasible to operate from regular runways due to low weight/force ratios.

Further, UAVs do not need landing gear, parachutes, air bags or other means for landing besides what is needed for this system resulting in savings in weight and drag. In one option, a storage comprises a plurality of storage positions. The control unit is then arranged to control the arm to put captured UAVs in empty storage positions and to fetch UAVs for launch from storage positions having UAVs. Thereby, a large number of UAVs can be operated at the same time by one or a plurality of ground stations.

In one option, one or a plurality of the storage positions comprise means for performing at least one of the following services on a stored UAV:

-transferring of data from the UAV to the ground station;

-transferring mission data from the ground station to the UAV;

-uploading software or other data to the UAV;

-system testing the UAV;

-filling of fuel to the UAV;

-charging batteries on the UAV;

-inspection of the UAV such as visual inspection.

In one option, the controllable arm is elastic, wherein a dampening and elastic connection to the captured UAV reduces risk of damage to both the controllable arm and the UAV.

In one option, the at least one controllable arm comprises means for detachably fixating the UAV to the arm.

On one option, the system comprises a widespread catching device adapted to catch an in-flight UAV missing the meeting point.

In one option, the system comprises at least one weather sensing unit located in a vicinity of the ground station. In accordance with this option, the weather sensing unit is arranged to transmit weather data to the computing unit, and the computing unit is arranged to determine an appropriate launching direction based on the weather data or to determine the meeting point based on the weather data. In one option, the ground station is at least partially enclosed in a weather protecting surrounding. In one option, the means for communicating with UAVs are arranged to communicate by radio or optically.

In one option, the ground station comprises a UAV launch mechanism separated from the arm.

In one option, the ground station comprises:

means for communication with other ground stations, and

means for communication with an air control system,

wherein a plurality of ground stations cooperates in a cluster.

In one option, the UAVs comprise at least one onboard system mounted onboard the UAVs and arranged to communicate with the ground station when present within the range from the ground station. In one option, the ground station comprises means for capturing an in-flight UAV performing a landing manoeuvre such as a perched landing manoeuvre. The perched landing manoeuvre is for example defined as a manoeuvre wherein the UAV firstly commands a pitch-up control sequence and the UAV thereafter enters in a vertical high angle of attack state, whereby the UAVs speed is reduced.

The present invention also relates to a method for automatic launch and/or landing of UAVs, at a ground station for automatic UAV launching and landing, wherein the method comprises the steps of:

- computing a meeting point adapted for a landing manoeuvre of an in-flight UAV approaching the ground station; - guiding the UAV approaching the ground station for landing based on the calculated meeting point;

- capturing the UAV at the calculated meeting point with a controllable arm located at the ground station,

- controlling the at least one arm to move the UAV between the meeting point and at least one storage position, and

- launching the UAV from said controllable arm or another controllable launch mechanism. In one option, at least one of the following steps is performed at the storage position:

-charging batteries carried by the UAV;

-filling fuel to the UAV;

-transferring data to the UAV;

-transferring software to the UAV;

-transferring data from the UAV to the ground station;

-bringing the UAV from a storage position of a nest;

-inspecting the UAV visually. In one option, preceding the landing manoeuvre of the UAV the method comprises the steps of:

-providing geographical navigational data to UAV's approaching the ground station;

-receiving weather data to the ground station from a weather sensing unit;

-calculating navigational instructions based on the weather data; -adapting navigational data according to geographical data and navigational instructions;

-guiding the UAV towards the ground station in interaction between the ground station and the UAV based on the adapted navigational data. In one option, the method comprises receiving at the ground station instructions from an operator, or an air control system, to launch at least one UAV

BRIEF DESCRIPTION OF THE DRAWINGS

Fig 1 shows an example of a system for handling a plurality of UAVs.

Fig 2 shows schematically an example of an arrangement at a ground station.

Fig 3 shows schematically an example of a storage position in the ground station. Fig 4 is a block scheme schematically illustrating a ground station system. Fig 5 shows schematically a UAV catching device. Fig 6 shows schematically an enclosing of the ground station.

Fig 7 is a flow chart illustrating an example of a method for automatic landing of a UAV at a ground station.

Fig 8 is a flow chart illustrating an example of a method for automatic launch of a UAV at a ground station.

DETAILED DESCRIPTION

In Fig 1 , a system 100 for handling a plurality of UAVs 1 10 comprises at least one ground station (in the illustrated example two ground stations) adapted for automatic UAV launching and landing. The system 100 also comprises an air control system 130. The air control system is arranged to communicate with the ground station(s) for example over a link 140. In one example, the ground stations are arranged to cooperate in clusters. For example, the air control system 130 may be arranged to coordinate activities of a plurality of ground stations 120 so that the plurality of ground stations operate in one cluster. In the illustrated example, the ground stations are arranged to communicate also with other ground stations so as to enable coordination of activities.

The ground stations 120 may be arranged to operate tenths or hundreds of UAVs operating in the air at the same time and parked at the ground station(s) between missions in the air. The ground stations are further arranged to communicate with UAVs operating in the air around the ground stations(s). The ground station comprises means for communication with UAVs present within a range from the ground station. The means for communicating with UAVs are in one example arranged to communicate by radio or optically. When the UAV comes within the given range a link 150 may be established between the ground station and the UAV. This link may be regarded as a short distance link. In one example, the UAV 1 10 is small, characteristically about 2-50 kilos in weight. In one example, at least some of the UAVs are fixed wing UAVs. The UAVs may have a weight/force relation smaller than one. The automatic launching and landing mechanism allows for a vehicle which may be optimised to an extent where ordinary take-off is not possible thus allowing for a lower weight/force relation. The UAVs may for example be formed out of polymer reinforced with glass fibre, carbon fibre, carbon nanotubes or some other material. The UAVs may be driven by a propulsion system that is electrical or by a combustion engine. The UAVs propulsion system may also be a hybrid system, combining for example a liquid energy storage and converter such as a fuel cell, an intermediate electrical storage such as a battery and an electrical propulsion device such as an electrical motor coupled to a propeller. In one example, the UAVs are operating autonomously in the air until landing is requested. Landing may be requested by the UAV sending a landing request to at least one of the ground stations 120. Alternatively, landing is requested by an operator of the air control system 130 sending the landing request to the UAV and/or to the ground station. Irrespectively, communication is performed such that both the UAV 1 10 and ground station 120 know that landing has been requested. In an example with multiple operating ground stations 120, the landing request may comprise an identification of a requested ground station. The request may then be evaluated by the requested ground station and be confirmed or denied. The confirmation/denial may be based on availability. In one example, navigation during flight outside a given range from the ground station is performed using GPS or other known navigation methods.

In Fig 2, a ground station 220 comprises an arrangement 221 for launching UAVs and for capturing in-flight UAVs. The arrangement 221 for launching UAVs and for capturing in-flight UAVs comprises in one example a unit with at least one controllable arm 222 adapted for launching UAVs and for capturing in-flight UAV. The at least one arm comprises in one example a robotic arm 222 provided with a grabbing device 224. The robotic arm is in one example mounted on a rotatable base 223. In one example one separate arm is used for capturing UAVs and another arm is used for launching UAVs. In another example the same arm can be used both for capturing in-flight UAVs and for launching UAVs. The ground station may be furnished with one or several arms for capturing in-flight UAVs and one or several arms for launching UAVs. In one example, at least the arm for launch is formed in another way than as an arm, for example as a pneumatic, electrical or in another way actuated catapult.

The controllable arm 222 for capturing in-flight UAVs is in one example adapted to capture a UAV with low stress and low physical wear and tear. For example, the arm may be elastic. Alternatively it may comprise a damper. In yet another example the arm is controlled to follow the UAV in its motion so as to avoid impact. Conversely, a part of the UAV caught by the arm may be provided with a damper. The controllable arm for capturing in-flight UAVs and/or launching UAVs comprises in one example means for fixating the UAV to the arm such as but not limited to: electromagnetic attachment, mechanical grasping mechanism or a rope-and-hook attachment.

Further, the ground station comprises or is associated to a storage 225, for storage of UAVs. In the illustratated example, the storage is formed as a conveyor belt 226 having a plurality of storage positions 227. In the illustrated example, two storage positions are shown, one empty and one storing a UAV. In Fig 3, a storage for storage of UAVs may comprise means for performing at least one of the following services when the UAV is stored:

-transferring of data from the UAV to the ground station,

-transferring mission data from the ground station to the UAV;

-uploading software or other data to the UAV;

-system testing the UAV;

-filling of fuel to the UAV;

-charging batteries on the UAV;

-visual inspection of the UAV. In the illustrated example, an UAV 410 having a first contact part such as a female contact 431 is arranged to be stored in a storage position 237 having a corresponding second contact part such as a male contact 432. The contact part of the storage position is in one example provided with self centering means 333. The self centering means 333 are for example formed as a truncated cone having an open end at the larger diameter for receiving the first contact part and the second contact part formed in the other end. In one example, the contact is electrical and/or optical. Altenatively, or in addition thereto, the contact comprises at least one tap for example for filling fuel to the UAV.

In Fig 4, a ground station system 450 comprises a UAV measurement system 451 arranged to measure data associated to a UAV; a launch and landing control system; a communication unit 453 and optionally a device for measuring environmental conditions 454. In one example, all components of the ground station system are installed at the ground station. Alternatively, some parts of the ground station system are arranged in the vicinity of the ground station. Those parts are then in communication with the ground station for example wirelessly.

The UAV measurement system 451 is as indicated above arranged to provide measurements of the UAV. In one example, the UAV measurement system 451 is arranged to measure the position, angle and velocity of the UAV. Accordingly, the measured information comprises for example position information, angle information and velocity information. For example, the following data may be measured: position, yaw, pitch, roll and/or speed of the UAV. In one example, the UAV measurement system is installed partly at the ground station and partly at the UAV. The measurement system comprises for example cameras, laser IR, radar, ultrasonic equipment, etc.

In the illustrated example, the device for measuring environmental conditions 454 comprises at least one wind sensor. The at least one wind sensor is in one example arranged to measure wind direction and wind strength. The wind sensor(s) is located at the ground station or in the vicinity thereof. By using a plurality of wind sensors, the accuracy of the measurements may be approved. The wind direction may be measured both in horizontal and vertical direction.

When the UAV is measured in by the UAV measurement system, the control of the UAV is in one example taken over by the launch and landing control system 452 from the UAV control system. The launch and landing system comprises a control unit 455 and a computing unit 456. The control unit 455 is arranged to control the arrangement for launch and capture of UAVs. The computing unit 456 is in one example arranged to calculate a landing manoeuvre for the UAV based on the data measured by the UAV

measurement system. In one example, the landing manoeuvre is a stall manoeuvre. The communication unit 453 is arranged to transmit and to receive information over the link described above so as to coordinate the landing manoeuvre.

The computing unit 455 is further arranged to compute a meeting point between the arm and one in-flight UAV. The control unit is then arranged to control the at least one arm to receive the UAV at the meeting point. The meeting point is in one example determined based on data from the UAV measurement, the wind sensor(s) and from the constraints of a volume around the ground station within which the capture arm or capture arms are capable of catching the UAVs. The communication between the UAV and ground station is used so as so secure that the velocity of the UAV and inflight direction are within acceptable limits.

The launch and landing control system 452 is further arranged to control the at least one arm to launch a UAV. In one example, the computing unit is arranged to determine a meeting point, or launch point, for the launching arm so as to launch the UAV in a desired direction. For example wind measurements can be used in determining the launch point. The launch arm may operate like a catapult.

The launch and landing control system 452 is further arranged to control the at least one arm to move between the meeting point for the landing vehicle and at least one storage for UAVs. The storage comprises in one example a plurality of storage positions. The launch and landing control system is then arranged to control the arm to put landed UAVs in empty storage positions and to capture UAVs for launch in storage positions having UAVs.

In Fig 5, a widespread catching device 534 is arranged in association with a ground station 520. In one example, the widespread catching device is provided adapted to catch an in-flight UAV missing the meeting point. When the UAV comes in for landing something can happen, which forces the UAV out of its course. If this happens before a point-of -no-return, the landing manoeuvre is aborted and the UAV can make another try. If it happens after the point of no-return, the performance of the UAV will not allow the UAV to abort the landing. In this situation, the widespread catching device catches the UAV in a controlled manner. The UAV can then be manually removed from the widespread catching device. In one example, the widespread catching device is a net. The catching device can be mounted in relation to the arm such that the net is placed behind the arm irrespectively from which direction the UAV comes in for landing. Alternatively the widespread catching device is released only at an emergency so as to catch the UAV out of course. In Fig 6, the ground station 620 is at least partially enclosed in a weather protecting surrounding 635. The ground station is for example arranged in a container.

In Fig 7, a method 700 for automatic launch and/or landing of UAVs comprises a number of steps as described below. Generally, the UAV is flying autonomously. However, when instructed to land, a landing procedure is initiated. In a first phase for landing, the UAV is guided 771 towards a ground station. In one example, the instruction to land comprises an identity of that ground station at which the UAV is instructed to land. Alternatively, the UAV is arranged to decide at which ground station landing is to be performed. The decision is for example based on flight conditions of the UAV and/or distances to neighbouring ground stations. The guiding of the UAV towards the ground station in this first phase is in one example based on GPS navigation. In one example, information is sent to the UAV indicating from which direction in-flight is to be carried out. The information indicating from which direction in-flight is to be carried out is based on the wind direction and wind strength measured at the ground station at which the UAV is intended to land.

In detail, the first phase of guiding the UAV to the ground station comprises in one example the steps of providing geographical navigational data to UAV's approaching the ground station; receiving weather data to the ground station from a weather sensing unit; calculating navigational instructions based on the weather data; adapting navigational data according to geographical data and navigational instructions; and guiding the UAV towards the ground station in interaction between the ground station and the UAV based on the adapted navigational data.

When the UAV is within a predetermined range from the ground station selected for landing, a second phase for landing is initiated. In the second phase, the UAV is performing a landing manoeuvre. In one example, the predetermined range is that range at which the above described measurement system at the ground station has first provided measurements of the UAV. Communication is performed continuously between the UAV and the landing control system during the landing manoeuvre. If the landing manoeuvre fails, the landing can either be aborted or the UAV can be steered into the catching mechanism, as discussed above. The landing manoeuvre comprises the steps of computing 772 a meeting point between the UAV and a controllable arm on the ground station and guiding 773 the UAV conducting the landing manoeuvre towards the meeting point. The landing manoeuvre is in one example a perched landing manoeuvre, wherein a fixed-wing UAV does a stall-manoeuvre reducing the speed of the UAV before reaching the meeting point. The controllable arm then captures 774 the UAV at the meeting point. Thereafter, the arm is controlled to move 775 the UAV to a storage position. At the storage position, maintenance is performed 776 at the UAV and/or data collected by the UAV during flight is downloaded from the UAV. The maintenance and/or data download is performed automatically at the storage position without the need for manual operation. The maintenance and/or data download is performed either with the UAV fixated at the controllable arm or released from the arm.

In detail, performing maintenance comprises at least one of the following measures: charging batteries carried by the UAV; filling fuel to the UAV; and inspecting the UAV visually. In detail, data collected by the UAV during flight downloaded at the storage position comprises sensor data collected by onboard sensors and/or rout data related to the route performed by UAV.

In Fig 8, a method 800 of launching UAVs from a ground station is illustrated. In a first step, an instruction to launch a UAV is received 881 in the ground station. In one example the instruction comprises information related to which UAV is intended for launch. The instruction is for example received from an operator, or an air control system. Based on this instruction the UAV is prepared 882 for launch in its storage position. If no UAV is placed in a storage position or if the requested UAV is not placed in a storage position, wherein maintenance and/or upload/download of data can be performed, the controllable arm can then be arranged to move a UAV to one storage position. The UAV may in one example be brought from a storage position in an nest. The preparation may comprise transferring mission data from the ground station to the UAV; uploading software or other data to the UAV; system testing the UAV; filling of fuel to the UAV; charging batteries on the UAV; and/or visually inspecting the UAV. The preparations are performed either with the UAV fixated at the controllable arm or released from the arm. Further, a launch manoeuvre is calculated 883. In one example, the launch manoeuvre is calculated based on a wind direction, wind strength and characteristics of the UAV such as weight. Thereafter control unit is arranged to control the arm to fetch 884 the UAV prepared for launch and, if applicable, place 885 the UAV in a launch mechanism, and to perform 886 the calculated launch manoeuvre.