Unmanned flying vehicle

Abstract

There is provided a drone comprising, a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in relation to each other, so that the propeller provides thrust in the direction of the shaft, where the main body rotates around its longitudinal axis, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other, the drone comprising a control device arranged to control the speed of rotation of the driving means to control the thrust and further arranged to control the flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main body in relation to an external frame of reference, the second rotation speed being referred to as roll speed, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, said longitudinal axis rotating around the flight direction of the drone, the flight direction being in relation to the external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis (roll speed), where the control device is arranged to determine the orientation of the longitudinal axis of the main body in relation to the external frame of reference with a frequency that is higher than the roll speed and adjust the thrust during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of attack, thereby adjusting the flight direction of the drone.

Description

[0001] Unmanned flying vehicle

[0002] Field of the invention

[0003] This invention relates to an unmanned flying vehicle (UAV), such as a drone.

[0004] Background

[0005] Unmanned aircraft, sometimes referred to as drones, are increasingly used for recreation and also for surveillance and other tasks. There is a need for a drone that can fly at high speed which would provide an increased challenge to the user when flying for recreation.

[0006] It would also be useful to have a drone that has low weight, is easy to manufacture, can be manufactured at low cost and that has few moving parts.

[0007] It would also be useful to have a drone that could be used to defend against hostile drones.

[0008] This disclosure solves this and other problems.

[0009] Summary of the invention

[0010] In a first aspect of the invention there is provided a drone comprising, a main body which is elongated and having a longitudinal axis, the main body being rotatably attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in relation to each other, so that the propeller provides thrust in the direction of the shaft, where the main body rotates around its longitudinal axis, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other, the drone comprising a control device arranged to control the speed of rotation of the driving means to control the thrust and further arranged to control a flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main body in relation to an external frame of reference, the second rotation speed being referred to as roll speed, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, said longitudinal axis rotating around the flight direction of the drone, the flight direction being in relation to the external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis (roll speed), where the control device is arranged to determine the orientation of the longitudinal axis of the main body in relation to the external frame of reference with a frequency that is higher than the roll speed and adjust the thrust during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of attack, thereby adjusting the flight direction of the drone.

[0011] The drone provides a simple and low-cost construction that provides a drone that is capable of flying at high speed.

[0012] In various embodiments, the drone has a center of mass and the direction of thrust provided by the propeller body is not directed trough the center of mass of the drone. In various embodiments, the center of mass is in the main body, and the control device is configured to adjust the thrust when the center of mass is in a position relative to the direction of thrust, such that adjusting the thrust adjusts the orientation of the longitudinal axis of the main body towards a desired flight direction, in relation to the external frame of refence.

[0013] In various embodiments, the control device is configured to determine a plane that goes through a desired flight direction and the current flight direction and where the determination of the orientation of the longitudinal axis of the main body involves determining at which point during revolution of the longitudinal axis the direction of thrust is in the plane, and the point is used to adjust the thrust.

[0014] In various embodiments, the shaft is arranged at a fixed angle to the longitudinal axis of the main body. In various embodiments, the direction of thrust is parallel to the longitudinal axis of the main body, but does not go through the center of mass of the drone.

[0015] In various embodiments, the angle of the longitudinal axis to the flight direction (angle of attack) is caused by an air flow modification surface. In various embodiments, the air flow modification surface is arranged to interact with the air flow over the drone during flight, thereby providing a force in a direction perpendicular to the longitudinal axis of the main body. The air flow modification surface may be a fin or a canard, for example a canard which is placed in front of the center of mass of the drone. Preferably there is a pair of fins or a pair of canards.

[0016] In various embodiments, the angle of the longitudinal axis to the flight direction (angle of attack) is at least partly caused by an air flow modification surface and in addition the drone has a center of mass and the direction of thrust provided by the propeller body is not directed trough the center of mass of the drone.

[0017] In various embodiments, the driving means comprises, or is, a brushless electrical motor. This provides a cost-efficient manner to provide fast control during a subsection of a revolution of the main body.

[0018] The control device may be configured to use a waiting time, said waiting time defining when, during a complete revolution of the longitudinal axis in relation to an external reference, a thrust control signal should be initiated by the control device. This makes it possible to handle lag times in the drone. The waiting time may be determined based on one or more of: current thrust settings, current drone speed, ambient air temperature and air pressure. In various embodiments, the waiting time is determined based one or more of ambient air temperature and air pressure, and the control device is arranged to, before flight, receive and store data regarding ambient air temperature or ambient air pressure, and to use the data during flight to determine the waiting time. The waiting time may be determined as the time from a time point when the orientation of the longitudinal axis, or the position of the drone, in relation to an external frame of reference is determined, until the change in thrust should be provided by the propeller body in order to adjust the flight direction of the drone, minus a predetermined lag time.

[0019] The waiting time may be determined as a predetermined lag time period plus a roll-speed dependent time period.

[0020] In some embodiments, the control device is arranged to adjust the thrust during a subsection of a first complete revolution of the main body and again adjust the thrust during a subsection of a second complete revolution of the main body, the second revolution being the revolution after the first revolution.

[0021] In various embodiments, where the control device comprises roll speed determination means arranged to determine the roll speed and where the control device is configured to use the roll speed to determine the waiting time.

[0022] In various embodiments, the control device is further configured to: determine the orientation of the longitudinal axis of the main body in relation to a target direction in the external frame of reference using a guidance sensor, and where the target direction is provided by an external source of electromagnetic waves, the control device being configured to determine the orientation of the longitudinal axis of the main body of the drone in relation to the target direction. In various embodiments, the electromagnetic waves is a laser beam and the guidance sensor is a laser sensor.

[0023] In various embodiments, the drone is configured to have a kinetic energy of from 1000 J to

[0024] 10000 J during flight. In a second aspect of the invention there is provided a method in an unmanned aerial vehicle (drone) the drone comprising a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in relation to each other, where the main body rotates around its longitudinal axis, so that the propeller provides thrust in the direction of the shaft, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other the drone comprising a control device arranged to control the speed of rotation of the driving means to control the thrust and further arranged to control the flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main in relation to an external frame of reference, the second rotation speed being referred to as roll speed, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, said longitudinal axis rotating around the flight direction of the drone, the flight direction being in relation to an external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis, the method comprising, determining the orientation of the longitudinal axis of the main body in relation to an external frame of reference with a frequency that is higher than the roll speed , and adjusting the thrust during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of attack, thereby adjusting the flight direction of the drone. In various embodiments, the control device uses a waiting time, said waiting time defining when, during a complete revolution of the longitudinal axis in relation to the external reference, a thrust control signal should be initiated.

[0025] In one embodiment there is provided an unmanned aerial vehicle (drone) comprising, a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in relation to each other, where the main body rotates around its longitudinal axis, so that the propeller provides thrust in the direction of the shaft, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other, the drone comprising a control device arranged to control the speed of rotation of the driving means and control the flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main body in relation to an external frame of reference, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, said longitudinal axis rotating around the flight direction of the drone, the flight direction being in relation to an external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis, where the control device is arranged to determine the angle of the longitudinal axis of the main body in relation to a external frame of reference with a frequency that is higher than the frequency of rotation of the main body in relation to an external frame of reference and adjust the rotation speed of the driving means during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of the longitudinal axis of the main body, thereby adjusting the flight direction of the drone.

[0026] In various embodiments, the control device is arranged to decrease the rotation speed when the longitudinal axis of the main body points in a desired flight direction or arranged to increase the rotation speed when the longitudinal axis of the main body points away from the desired flight direction. The angle of the longitudinal axis to the flight direction may be caused by an air flow modification surface. The air flow modification surface may be arranged to interact with the air flow over the drone during flight, thereby providing a force in a direction perpendicular to the longitudinal axis of the main body. The air flow modification surface may be a fin or a canard. A canard may be placed in front of the center of mass of the drone.

[0027] In various embodiments, the angle of the longitudinal axis to the flight direction is obtained by a reaction engine which is arranged to provide a force that is perpendicular to the longitudinal axis of the main body.

[0028] In various embodiments there is provided a method in an unmanned aerial vehicle (drone) the drone comprising a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in relation to each other, where the main body rotates around its longitudinal axis, so that the propeller provides thrust in the direction of the shaft, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other, the method comprising: determining the angle of attack of the drone, adjusting the rotation speed of the driving means during a subsection of a complete revolution of the main body in order to adjust the angle of the longitudinal axis to the current flight orientation of the longitudinal axis of the main body, thereby adjusting the flight direction of the drone.

[0029] In a third aspect of the invention there is provided a system comprising a drone according to the first aspect of the invention, the system further comprising a launcher. The launcher may comprise a plurality of drones. In some embodiments, the system comprises an illumination means, the illumination means arranged to provide electromagnetic waves configured to be detected by a guidance sensor of the drone. The illumination means may be arranged to provide a beam that is configured to be reflected or scattered by a target to provide guidance of the drone to the target.

[0030] In a fourth aspect of the invention there is provided a method for neutralizing a hostile drone comprising: guiding a drone according the first aspect of the invention to collide with the hostile drone, or using a system according to the third aspect of the invention, where the system comprises an illumination system, to collide with the hostile drone, where the illumination means of the system is used to guide the drone to collide with the hostile drone, wherein the guided drone is flying and having a sufficient kinetic energy during flight to neutralize the hostile drone.

[0031] The accompanying drawings form a part of the specification and schematically illustrate preferred embodiments of the invention, and serve to illustrate the principles of the invention.

[0032] Fig. 1 is a schematic drawing of a cross section of a drone according to some embodiments. Fig. 2 is a schematic drawing of a drone seen from behind according to some embodiments. Fig. 3 is a schematic drawing of a flight path of a drone in straight flight, according to some embodiments.

[0033] Fig. 4 is a schematic drawing of a flight path of a drone according to some embodiments.

[0034] Fig. 5 is a schematic drawing of a drone according to some embodiments.

[0035] Fig.6 is a schematic drawing of a drone seen from behind according to some embodiments. Fig. 7 is a is a schematic drawing of a flight path of a drone according to some embodiments. Fig. 8 is a schematic drawing of a drone according to some embodiments.

[0036] Fig. 9 is a schematic drawing of a control device according to some embodiments. Fig. 10 is a flow chart showing certain steps of a method according to some embodiments. Fig. 11 is a schematic drawing of a cross section of a drone according to some embodiments. Fig. 12 is a schematic drawing of an example of a drone.

[0037] Fig. 13 is a schematic drawing of a drone at various time points during flight.

[0038] Fig. 14 is a schematic drawing of a cross section of a drone according to some embodiments. Fig. 15a is a schematic drawing of a drone at two different time points during flight.

[0039] Fig 15b is a schematic drawing of a drone at two different time points during flight.

[0040] Fig. 16 is a schematic drawing of a drone seen from behind during two different time points. Fig. 17 is a polar diagram.

[0041] Fig. 18 is a graph.

[0042] Fig. 19 is a flow chart that shows a method.

[0043] Fig. 20 is a schematic drawing of a system.

[0044] Fig. 21 is a schematic drawing of a drone and a guiding beam.

[0045] Fig. 22 is a schematic drawing of a drone seen from behind and a transverse section of a guidance beam, at two different time points.

[0046] Detailed description

[0047] With reference to Fig 1, unmanned aerial vehicle 1 (drone 1) comprises a main body 2 which is elongated and has a longitudinal axis 3. The main body 2 may have the approximate shape of elongated tube that comprises various other components described herein. The main body 2 may be a fuselage. The drone 1 may have a generally elongated shape. The drone may have a front end that has a shape that is aerodynamically suitable to provide low drag, such as a bullet shape or similar shape. The drone may have a nose cone 65 (see for example Fig 21). The drone 1 may have any suitable length, from centimetre scale to meter scale. The main body 2 or the drone 1 may have an axis of symmetry that goes through the longitudinal axis of the main body 2 of the drone 1. In some embodiments, the longitudinal axis 3 may go through the center of mass 16 of the drone 1. The elongated main body 2 is rotatable attached at one end of the elongated body 2 to a propeller body 4 with a shaft 5. The shaft 5 is rotationally fixed in relation to either the main body 2 or the propeller body 4. The main body 2 and the propeller body 4 are arranged to rotate in relation to each other around the axis of the shaft 5. The propeller body 4 has propeller blades 9 and is arranged to provide thrust in the direction of the shaft 5. The rotation of the propeller body 4 in relation to an external frame of reference provides the thrust. As used herein an "an external frame of reference" may be a cartesian three- dimensional coordinate system. The external frame of reference is external in relation to the drone. The drone may have six degrees of freedom of movement in relation to the coordinate system.

[0048] The propeller body 4 may have any suitable number of propeller blades 9 such as 2, 3, 4, 5, or more. In some embodiments the propeller body 4 is a ducted fan or ducted propeller. The drone 1 comprises driving means 6 that are arranged either in the main body 2 or the propeller body 4, but preferably in the main body 2, due to size constraints in the propeller body 4. The driving means 6 may be an electrical motor, preferably a brushless electrical motor, or a brushless DC electric motor (BLDC), also known as an electronically commutated motor. For example, the phases of the electromagnets of the motor are controlled by software which may comprise a mathematical model. The driving means 6 is powered by a power source 8 such as a battery or a fuel cell. In other embodiments, the driving means 6 may be a non-electric motor, such as a combustion engine. The propeller body 4 provides thrust that makes the drone 1 fly. The driving means 6 driving the propeller body 4 provides propulsion for the drone 1. It is preferred that the drone 1 has a single thrust axis. A power line provides voltage from the battery 8 to the driving means 6. The battery 8 may also power control device 7. The battery may for example be a lithium ion battery.

[0049] NewtDrive from Zubax, Estonia (htt s: / / zubax.com) is a useful kit comprising an electric motor, control chip and software that may be used for driving means 6 and control device 7. Examples of useful software to be used in control device 7 include InstaSPIN-BLDC from Texas Instruments. The driving means 6 is mechanically connected to the shaft 5 and drives rotation of the main body 2 and the propeller body 4 in relation to each other by rotating the shaft 5. Taking the view from an external frame of reference, when one body is brought into rotation the other body will counter rotate due to counter torque. If the rotation of the propeller body 4 is clockwise the rotation of the main body 2 will the counterclockwise and vice versa. Hence the main body 2 and the propeller body 4 will rotate in opposite directions in relation to an external frame of reference.

[0050] Arrow 17 in Fig 2 indicates rotation of the propeller body 4 and arrow 18 indicates rotation of the main body 2. Preferably, the propeller body 4 is arranged to rotate with a higher speed than the main body 2, in relation to an external frame of reference. This may be due to the main body 2 having a larger air resistance than the propeller body 4, in particular larger air resistance in the rolling direction. For example, the main body 2 may have fins 20 (Fig 5). This counteracts rolling. The main body 2 may have wings with a plane that goes through the perpendicular axis 3. The purpose of the wings may be to slow down the rotation of the main body 2 in relation to the propeller body 4. Hence, the wings may counteract rolling. The main body 2 may have a larger mass than the propeller body 4, and this may cause the main body 2 to rotate with a speed that is lower than the rotation speed of the propeller body 4 The speed of rotation for the propeller body 4 may for example be from three times to twenty times, or from five to fifteen times, faster than the speed of rotation of the main body 2. As an example, the propeller body 4 may have an rpm of 40 000 whereas the main body 2 may have an rpm of 4000. In a different example, the propeller body 4 has a rpm of 1000 and the main body 2 has a rpm of 100. In various embodiments, the propeller body 4 has an rpm of from 1000 rpm to 100 000 rpm, such as from 20 000 rpm to 60000 rpm, for example from 30 000 rpm to 50 000 rpm. In various embodiments the main body 2 has an rpm (roll speed) o from 50 rpm to 10000 rpm, such as from 1000 rpm to 5000 rpm. These are examples of rotation speeds at steady state during flight.

[0051] The drone 1 further comprises a control device 7 arranged to control the speed of rotation of the driving means 6, thereby controlling or adjusting the thrust, and control the flight direction of the drone 1. The control device 7 comprises any suitable combination of software and hardware. The control device 7 may comprise a flight controller. The control device 7 may for example control the voltage or the current provided from the power source 8 to the driving means 6 and thereby control the speed of rotation of the propeller body 4 and the main body 2. The control frequency may be predetermined. The control frequency should be so fast that the speed of rotation can be controlled or adjusted at least once, or at least twice, or at least three times or at least four times, or more, such as at least 10, 50 or 100 times per revolution of the main body 2 in relation to an external frame of reference.

[0052] The control device 7 is arranged to determine the orientation of the longitudinal axis 3 of the main body 2 in relation to an external frame of reference, as discussed in more detail below. In particular, the control device 7 may determine the angle 24 between the longitudinal axis 3 and the current flight direction 21, also referred to as the angle of attack 24. The rotation of the main body 2 along the longitudinal axis 3 coincides with the rotation of the angle of attack 24 as shown in Fig. 3. The drone 1 is configured to continuously roll as shown in Fig 3. This continuous roll is also carried out during straight flight. This rotation occurs with a roll speed (or roll frequency). Furthermore, the control device 7 may be arranged to determine the roll angle 26 of the of the main body 2 in relation to an external frame of reference. The roll angle 26 may be determined as an angle between the force vector 12 and the desired flight direction 22 as shown in Fig. 2. The control device 7 may be arranged to determine the roll speed of the main body 2, as described in more detail below. The desired flight direction 22 may be considered as a direction from the drone 1, for example towards a desired future waypoint 29 (see for example Fig 16). The direction control described herein may be used to keep the drone 1 flying straight, for example towards a desired waypoint or target in space.

[0053] With reference to Figs 3-4, the drone 1 may be configured to provide, during flight, a force 12 that is perpendicular to the longitudinal axis 3 of the main body 2. This perpendicular force 12 can be provided in various ways and is described further below. Perpendicular force 12 may be applied such that it provides torque on the drone 1. Hence the perpendicular force 12 may be applied forward or rear of the center of mass 16 of the drone 1. The center of mass 16 should preferably be in the main body 2.

[0054] Drone 1 is configured such that, during flight, longitudinal axis 3 of the main body 2 is oriented with angle of attack 24 which is greater than zero from the flight path of the drone 1. The longitudinal axis 3 of the main body 2 rotates around the flight direction 21 of the drone 2, where the flight direction 21 is determined in relation to an external frame of reference. The angle of attack 24 is present during straight flight of the drone 1. The perpendicular force 12 may cause the longitudinal axis 3 of the main body 2 to be oriented with angle of attack 24 which is greater than zero from the flight path of the drone 1, and cause the longitudinal axis 3 of the main body 2 to rotate around the flight direction 21 of the drone 2, where the flight direction 21 is determined in relation to an external frame of reference.

[0055] The angle of attack 24 may have any suitable value. During straight flight, the angle of attack 24 may be more or less constant, and be for example up to 30°, or up to 15° or up to 10° or up to 5°, or up to 3°. However, it may be necessary to adjust the angle of attack 24 to control the flight direction as described herein order to keep the drone 1 flying straight, for example to counteract intrinsic instability of the drone 1 to counteract influence from external factors such as wind or turbulence. In some embodiments, the angle of attack can vary with a delta of from 1° to 10° more preferably from 1° to 5° during flight, this delta of the angle of attack is controlled by the control device 6. The angle of attack 24 may be so small as to be difficult to detect for the naked eye during flight. The rotation of the longitudinal axis 3 of the main body 2 occurs with the same angular speed as the main body 2 rotates around the flight direction 21 as seen in Fig 3. Hence, the main body 2 will roll with respect to the flight direction 21 and the perpendicular force 12 will roll with the same speed. The roll is indicated with helical dashed line in Fig. 3.

[0056] Returning to Figs 1 and in particular Fig 2, the control device 7 is arranged to determine the orientation of the longitudinal axis 3 in relation to the external frame of reference, and adjust the rotation speed of (or provided by) the driving means 6 during a subsection 13 of a complete revolution of the main body 2 (in relation to an external frame of reference). As mentioned above, adjusting the rotation speed of the driving means 6 is also referred to as "adjusting the thrust" herein. Adjusting the thrust may refer to controlling the thrust such that the amounts of thrust departs from a baseline level of thrust. Adjusting the thrust by increasing the thrust may be referred to herein as pulsing the driving means 6, or pulsing the thrust.

[0057] Adjusting or pulsing the driving means is carried out in order to make the drone 1 assume a desired flight direction 22. Subsection 13 is indicated with dashed lines in Fig. 2, where it generally points in the desired flight direction 22. Subsection 13 may be less than 80% of a complete revolution, or less than 70 % of a complete rotation or less than 50 % of a complete revolution, or less than 25 % of a complete rotation or less than 15 % of a complete revolution, or less than 10% of a complete revolution or less than 5 % of a complete revolution.

[0058] Determining the orientation of the longitudinal axis 3 in relation to an external frame of reference may involve determining a plane that goes through the current direction of flight 21 and the desired flight direction 22 and determining when, during rotation, the longitudinal axis 3 (or the center of mass 16) is in the plane. The plane is indicated by arrows 21, 22 in Fig. 5. (The aforesaid method of determining the orientation of the longitudinal axis may also be used to determine the roll speed.) The driving means 6 may be adjusted depending on where, during rotation, the longitudinal axis 3 (and in some embodiments the center of mass 16) is in relation to the plane. For example, the driving means 6 may be pulsed when, during rotation, the longitudinal axis 3 is the plane.

[0059] The determination of the orientation of the longitudinal axis 3 and hence also the roll angle 26 in relation to an external frame of reference may be done with a frequency that is chosen so that it is higher than the highest frequency of rotation of the main body 2 in relation to an external frame of reference, preferably at least twice, or at least three times or at least fourtimes, or more, such as at least 10, 50 or 100 times per rotation of the main body, given the estimated maximum rotation speed of the main body 1. The frequency may be predetermined. The rotation speed of the main body 2 is typically between 50 rpm and 5000 rpm so the detection frequency is selected accordingly.

[0060] Determination of the orientation of the longitudinal axis 3 can be done in any suitable manner. In various embodiments, control device 7 comprises one or more sensors 54 for determining the orientation of the longitudinal axis in relation to an external frame of reference. The sensors 54 may for example be one or more gyroscopes.

[0061] Hence by "pulsing" the drive means 6 during subsection 13 of a revolution of the main body 2, a force that will control the flight direction 21 will be created, as described in more detail below. Pulsing the thrust may involve increasing or decreasing the thrust in relation to a baseline level of thrust during a subsection of a revolution of the main body 2, and then returning the thrust to the baseline level. An example is shown in Fig 17.

[0062] Now, looking in particular Figs 5, 8 and 11-16 the perpendicular force 12 that may be used to generate the angle of attack 24 can be achieved in various manners. In the following, various ways of generating the perpendicular force 12 will be described. In various embodiments, the various ways may be combined.

[0063] In a first embodiment which is shown in Fig 5, the perpendicular force 12 that causes the angle of attack 24 is caused by air flow modifications means, such as at least one air flow modification surface (such as a pair of fins or a pair of canards 14 or a flight control surface) arranged on the main body 2, or as a part of the outer surface of the main body 2, where said air flow modification means is arranged to interact with the air flow during flight, thereby providing a force 12 in a direction perpendicular to the longitudinal axis 3 of the main body 2. A pair of canards 14 may for example be arranged in front of the center of mass 16. The air flow modification surface may be fixed in relation to the main body 2. The control device 7 is then arranged to decrease the speed of rotation when the longitudinal axis 3 of the main body 2 points in the desired flight direction 22. When the speed of rotation is slowed down, the main body 2 will spend more time in the desired direction 22. Hence, driving means 6 will slow down causing rotation of the main body 2 to slow down. This will give the air flow modification means, such as canards 14, more time in that direction and thereby increase angle of attack 24. Hence, the drone 1 will change its flight path accordingly. However, as an alternative, the speed of rotation may be increased when the longitudinal axis 3 is directed away from the desired flight direction 22. Two canards 14 may be arranged in a common plane. Two fins may be arranged in a common plane.

[0064] The change in speed of rotation of the propeller body 4, may cause a slight change in the air speed of the drone, but the change in air speed is such that the change in perpendicular force 12 may be negligible. Force 12 may be considered as constant.

[0065] Fig 6 is a schematic drawing of a drone 1 seen from behind, where the current flight direction 21 is into the plane of the figure. The main body 2 of the drone 1 has two canards 14. Canards 14 provide a force 12, causing the longitudinal axis 3 of the main body 2 to be offset from the current flight direction 21 (angle of attack). Note that the direction of force 12 is upwards in Fig. 6 but downwards in Fig 5. The desired flight direction 22 is slightly upwards in Fig 6. The speed of rotation of the main body 2 is decreased when the longitudinal axis 3 of the main body 2 points upwards (as shown in the figure) for example when the longitudinal axis 3 is in subsection 13. This will cause the force 12 to work for a longer period of time in subsection 13 of the revolution, causing the angle 24 of attack to increase. This will cause the drone 1 to turn in that direction.

[0066] Fig. 7 shows how the drone 1 carries out a change or correction of flight direction. Drone 1 has as a current flight direction 21 and a desired flight direction 22. The driving means 6 and the control device 7 will provide decreased thrust at time T2 when the main body 1 is pointed towards the desired direction 22. The drone 1 will therefore spend more time with the longitudinal axis 3 of the main body 2 in that direction, and will therefore turn in that direction.

[0067] In Fig 5, two parallel canards 14 arranged on the front of the main body 2 provide the perpendicular force 12. The main planes of the canards 14 of Fig 5 is at an angle to the longitudinal axis 3 of the main body 2. When the main body 2 is arranged rear of the propeller body 4, the air flow modification mean may be one or more fins. The canards 14 or fins may be fixed to the main body 2.

[0068] In a second embodiment, shown in Fig 8, the main body 2 has a reaction engine 15, for example a rocket engine, such as for example a hydrogen peroxide powered rocket engine, that provides constant thrust 25 in at least a direction which is perpendicular to the longitudinal axis 3 of the main body 2. For the avoidance of doubt the reaction engine 15 does not have to be directed perpendicularly to the longitudinal axis, but may also provide some thrust in a different direction for example forwards. Any suitable reaction engine 15 using any suitable fuel may be used. The reaction engine 15 is preferably placed such that its reaction vector does not go through the center of mass 16 of the drone 1. The reaction device 15 may be placed far from the center of mass 16, for example close to an end of the main body 2, such as close to the front of the drone 1, in order to provide leverage. Just as in the first embodiment, the control device 6 is arranged to decrease the speed of rotation when the longitudinal axis of the main body 2 points in the desired flight direction. The reaction device 15 may be started by a start signal from the control device 7, for example upon launch or take-off of the drone 1.

[0069] The angle of attack 24 may be caused in yet different manners. In various embodiments, of which examples are shown in Figs 11-16, the drone has a center of mass 16 and the angle between the longitudinal axis 3 of the main body and the flight direction may be caused by the direction of thrust 28 provided by the propeller body 4 not being directed trough the center of mass 16 of the drone 1. The direction of thrust 28 may be associated with a direction and a point of application. The control device 7 may then be arranged to increase the thrust when the longitudinal axis 3 of the main body 2 points in a desired flight direction 21 or arranged to decrease the thrust when the longitudinal axis 3 of the main body 2 points away from the desired flight direction 21. This provides torque that changes the angle of attack 24 and importantly changes the orientation of the longitudinal axis 3 and the flight direction 21 The direction of thrust 28 may however, go trough the longitudinal axis 3 of the main body 2. Hence the direction of thrust 28 will rotate with the longitudinal axis 3 of the main body 2. Center of mass 16 is preferably in the main body 2, and the control device 7 is then preferably configured to adjust the thrust when the center of mass 16 is in a position relative to the direction of thrust, such that adjusting the thrust adjusts the orientation of the longitudinal axis 3 of the main 2 body towards a desired flight direction 22, in relation to the external frame of refence.

[0070] The control device may be configured to determine a plane 11 that goes through a desired flight direction 22 and the current flight direction 21 and where the determination of the orientation of the longitudinal axis 3 of the main body 2 involves determining at which point during revolution of the longitudinal axis 3 the direction of thrust 28 is in the plane 11 , and the point is used to adjust the thrust.

[0071] Hence the thrust vector 28 is offset from the center of mass 16 of the drone 1. When the thrust is pulsed, torque is provided about the center of mass 16 of the drone 1, which turns the longitudinal axis 3 of the drone 1. The control device 7 may then be arranged or configured to adjust the thrust when the center of mass 16 of the drone 1, in particular when the center of mass 16 is in the main body 2, is in a position relative to the direction of thrust 28, such that adjusting the thrust adjusts the angle of the longitudinal axis 3 of the main body 2 (angle of attack) towards a desired flight direction 22.

[0072] This can be achieved in different ways. In the embodiment shown in Figs 11-13 and Fig 15a, the shaft 5 is arranged at an angle, 27, preferably a fixed angle 27, to the longitudinal axis 3 of the main body 2. This will cause the drone 1 to fly with a nutating motion as shown in Fig. 13. Fig 12 is an example of a drone according to the embodiment of Fig 11. It is to be noted that angle 27 is shown slightly exaggerated in Figs 15a and 15b in order to increase the understanding.

[0073] The control device 7 may then be arranged to increase the speed of rotation of the propeller body 4 when the longitudinal axis 3 of the main body 2 points in a desired flight direction 21 or arranged to decrease the speed of rotation when the longitudinal axis 3 of the main body 2 points away from the desired flight direction 21. This provides torque about the center of mass 16 that changes the angle of attack 24. The center of mass 16 is typically fixed in relation to the longitudinal axis 3 of the main body 2, and hence it can be determined where the center of mass 16 is in relation to the desired flight direction 22 by determining the orientation of the longitudinal axis 3.

[0074] The angle 27 is preferably in the range up to 4°, but may be up to 60° or at least less than 90°. A suitable value for angle 27 may be from 1° to 3°. Hence the shaft 5 may be arranged at an angle 27 to the longitudinal axis 3 of the main body 2. Hence, as shown in Figs 11 and 12 the direction of thrust 28, which is directed in the direction of the shaft 5, will not go through the center of mass 16 of the drone 1. Fig 13 shows an example of how one drone 1 according to this embodiment is oriented in relation to an external frame of reference when flying in a flight direction 21.

[0075] Alternatively, as shown in Fig 14 the direction of thrust 28 is parallel to the longitudinal axis 3 of the main body 2, but offset from the center of mass 16 of the drone 1. In Figure 14 the direction of thrust 28 indicated by dashed line 28 that shows extension of shaft 5 is parallel to longitudinal axis 3 but does not go through the center of mass 16. This drone will also fly with a nutating motion similar to what is shown in Fig. 13.

[0076] Fig 15a shows how the direction of flight 21 is adjusted by providing torque. A drone 1 has a current direction of flight 21 and the orientation of the longitudinal axis 3 changes from time Ti to time point T2 as the main body 2 rolls. At time Ti the center of mass 16 is between the desired direction of flight 22 and the direction of thrust 28. Hence by pulsing the driving means 6 at time Ti the drone 1 will pitch upwards it the figure and assume a flight direction that is closer to the desired flight direction 22. At time T2 the thrust should be lower than at time Ti, such as for example baseline thrust.

[0077] Fig 16 shows a similar scenario as in Fig 15a but where the main body 2 of drone 1 is seen from behind and the drone 1 is flying (direction of flight 21) in towards the plane of the figure, hence the direction of flight 21 is perpendicular to the plane of the figure. The propeller body 4 is not shown. The direction of thrust 28 is directed in towards the plane of the figure or generally into the plane of the figure, but will vary slightly depending on the nutation of the drone 1. The desired direction of flight 22 is towards waypoint 29 which is located behind the plane of the figure. The main body 2 of the drone 1 is rotating as indicated by the circular arrow 18. The plane 11 that goes through the desired direction of flight 22 (towards waypoint 29) and trough the center of mass 16 is determined. The orientation of subsection 13 is determined by plane 11. The plane 11 is rotating in relation to the external frame of reference. By pulsing the driving means 6 when the direction of thrust 28 is in subsection 13, as at time T1 (Fig 15a), torque provided on the drone 1 will tend to pitch the longitudinal axis 3 of the drone 1 as indicated by arrow 30, i.e. towards waypoint 29, thereby changing the direction of flight. The higher level of thrust may be provided as long as direction of thrust 28 is in subsection 13. Shortly thereafter, at time T2, the main body 2 has rotated about 60 degrees and the direction of thrust 28 is outside subsection 13. Hence at time T2, the thrust should have returned to baseline thrust. As an alternative to increasing the thrust in subsection 13, the thrust can be decreased in a subsector phase shifted 180° in relation to subsection 13.

[0078] In figures 15a and 16 the drone 1 is configured such that the center of mass 16 is between the direction of thrust 28 and the desired flight direction 22 when the main body 2 points towards the desired flight direction 22 (see figure 15a). This may be preferred in some embodiments. However, in some cases or embodiments the longitudinal axis 3 may point away from the desired flight direction 22 when the center of mass 16 is between the direction of thrust 28 and the desired flight direction 22. The pulse of thrust is then phase shifted 180°. An example of such an embodiment is shown in Fig 15b. Hence in figure 15b the thrust should be increased at timeT2 in order to make the drone fly toward the desired flight direction 22.

[0079] The various embodiments may be combined. In particular, an air flow modification means such as a canard 14 (Figs 5-6) may be combined with a direction of thrust 28 that is offset from the center of mass 16, for example with angled shaft 5 (Fig 11-13, 15a) or parallel but offset (Fig 14). Hence in various embodiments, the angle of the longitudinal axis 3 to the flight direction 21 is at least partly caused by an air flow modification surface and in addition the drone 1 has a center of mass 16 and the direction of thrust 28 provided by the propeller body 4 is not directed through the center of mass 16 of the drone 1. An example is shown in Fig 15b, where the canard 14 produces a perpendicular force 12 that counteracts the direction of thrust 28 of the propeller body 4. In Fig 15b the driving means is pulsed at T2 in order to change the direction of flight towards the desired direction 22 and not pulsed at Ti. The drone of Fig 15b has air flow modification means 14 that provides a perpendicular force 12 that provides attack angle 24 and pulsing the thrust, thereby speeding up rotation at time T2 to counteract the perpendicular force 12 by allowing the canards to work a shorter time while the drone is directed as at in T2. Hence pulsing the thrust at time T2 decreases the attack angle 24. The air flow modifications means is particularly well suited to provide a perpendicular force at high speed while the offset of the direction of thrust 28 may be more suitable at low speed, for example when drone 1 is hoovering.

[0080] In general, in various embodiments, control device 7 comprises means to detect the current flight direction 21 and may have stored information about a desired flight direction 22. The control device 7 is then configured to adjust the flight direction 21 to make the drone fly the desired flight direction 22. The current flight direction 21 and the desired flight direction 22 may be provided in various manners.

[0081] The current flight direction 21 and the desired flight direction 22 may be determined in relation to the center of mass 16 of the drone 1.

[0082] Looking at Fig. 9, in various embodiments, the flight direction of the drone 1 is controlled by remote control. Hence the drone 1 may be a remotely piloted vehicle (RPV). For this purpose, the control device 7 may comprise a receiver 57 for receiving a wireless control signal from a separate input device 58. Communication may for example be carried out using the ELRS protocol or the Crossfire protocol and compatible hardware. A user may use external input device 58 with a transmitter to provide a wireless control signal to the control device 7. For example, a user may keep the drone 1 in sight and a use handheld input device 58 to guide the drone 1. A control signal may comprise a desired change of flight path for the drone 1.

[0083] In some embodiments, the desired flight direction 22 is a direction to a predetermined waypoint 29 stored in a memory of the control device 7. The control device 7 may comprise means for determining a desired flight direction 22 to a predetermined waypoint 29. The control device 7 may comprise a navigation system which may comprise means for determining a position of the drone 1 for example GPS or the like. The control device 7 may comprise means for determining the position of the drone 1 using dead reckoning such as an inertial navigation system, comprising for example one or more of an accelerometer, gyroscopes, altimeters, and a speed sensor. The control device may comprise a IMU (Intertial measurement Unit). The inertial navigation system may be used for determining a current flight direction 21.

[0084] In various embodiments, the current flight direction 21 or desired flight direction 22 is determined by one or more sensors receiving a guiding signal. Various means of controlling the flight of drone 1 from a distance are described below with reference to Figs. 20-22.

[0085] The control device 7 compares the current flight direction 21 with the desired flight direction 22 and adjusts the rotation speed of the driving means 6 during a subsection of a complete revolution of the main body 2 in orderto adjust the orientation of the longitudinal axis 3 of the main body 2, thereby controlling the flight direction 21 of the drone. Because of the high speed of rotation of the propeller body 4, propeller body 4 will make several complete revolutions at an adjusted speed, providing a pulse of thrust.

[0086] The control device 7 is configured to determine the orientation of the longitudinal axis 3 of the main body 2 in relation to an external frame of reference. Determination of the orientation of the longitudinal axis 3 may be done in various manners. In one embodiment an inertial navigation system is used to determine the orientation of the longitudinal axis 3. For example, one or more gyroscopes is used. The control device 7 may be able to detect the speed of rotation of the driving means 6. This may be done in any suitable manner, for example using a rotation speed sensor. For example, a hall effect sensor or an optical encoder may be used to detect the rotation speed of the driving means 6 or the shaft 5. In various embodiments, rotation speed is detected by detecting the back EMF (counter-electromotive force) from the driving means 6 or the shaft 5. The information may be used to control the speed of rotation to a desired rotation speed.

[0087] The control device 7 may be configured to initiate or provide a thrust control signal to the drive means 6 in order to adjust the thrust by adjusting the rotation speed of the driving means 6. In particular the driving means 6 may be pulsed during a part of a full rotation of the main body 2._Reaction times (lag time) of the components of the drone 1 are to be taken into account, for example circuit processing time in control device 7, reaction time of drive means 6 and inertia of the propeller blades 9, when increasing and decreasing the speed of rotation. Hence the actual thrust force may be provided with a lag time. The lag time may be more or less constant in one particular drone 1. Moreover, the time from when the position or orientation of the drone 1 is known to when the thrust should be delivered needs is taken into account. However, the roll speed of the main body may depend on air pressure, air temperature, air density, drone speed and speed of rotation of the propeller body 3. Hence the timing of the thrust control signal is important.

[0088] Fig 17 is a polar diagram showing the level of thrust (in a simplified manner because the thrust may not actually be a square wave as shown in the figure as it needs ramp-up) as a function of the orientation of the direction of thrust for the situation at time Ti in Fig 16, for the drone of Fig. 15a, as the main body 2 rolls. Hence, the phase will correspond to a certain time point. Hence the direction of thrust 28 depends on the orientation of the longitudinal axis 3 of the main body 2. This is an example only and the waiting time is relevant for all configurations of the drone 1 described herein, and the skilled person understands to adapt this embodiment to various possible configurations of drone 1. The direction of waypoint 29 in relation to the direction of the longitudinal axis 3 is indicated in Fig 17. The location of the waypoint 29 is determined in relation to an external point of reference determined at a previous time point 31. The external point of reference may for example be the position of the drone as determined by GPS at time point 31. In some embodiments, the orientation of the longitudinal axis 3 of the main body 2 in relation to an external point of reference, such as beam 60 (see below), is determined at time point 31. Looking at Fig 16 (Ti), the longitudinal axis 3 will be pointing towards the waypoint 29 at time Tl. Hence the driving means 6 should be pulsed (increased) at this time point in order to change the direction of flight 21. The control device 7 provides thrust as a pulse when the direction of thrust 28 is as indicated within subsector 13 in Fig 16 time Ti.

[0089] The control device 7 may use a waiting time which defines when, during a complete revolution of the longitudinal axis 3 in relation to an external reference, a thrust control signal should be initiated. The waiting time is preferably selected based on the roll speed, that is the rate of roll of the main body 2. The roll speed may depend on for example the thrust setting and the air pressure.

[0090] In various embodiments, the waiting time for a certain thrust adjustment is selected based on one or more of the current thrust settings, drone speed, air temperature, air density or the air pressure. Air pressure and air temperature may be used to determine an air density. For example, thrust setting or drone speed may be determined using data from the control device 7 and air pressure or ambient air temperature may be preloaded into memory 50, for example using input device 58, launcher 64 or hand held device 67, for example using a wireless communication protocol, before launch of the drone 1 and then used during flight. The drone 1 may comprise an air pressure sensor for determining the air pressure and the control device 7 may be configured to receive data from the air pressure sensor. The drone 1 may comprise a temperature sensor arranged for determining the ambient air temperature and control device 7 may be arranged to receive data from the temperature sensor. Memory 50 may store waiting times, for example as a lookup table, for various thrust settings, drone speeds, air temperatures, air pressures, or air densities, which enables control device 7 to select the appropriate waiting time, taking the roll speed and the lag time into account. In some embodiments, roll speed is determined and used to determine a waiting time. The control device 7 may comprise roll speed determination means arranged to determine the roll speed and where the control device 7 is configured to use the roll speed to determine the waiting time.

[0091] With reference to Fig 17 the waiting time may be determined as the time (total delay) from a time point 31 when the orientation of the longitudinal axis 3, or the position of the drone 1, in relation to an external frame of reference is determined, until the change in thrust should be provided by the propeller body 4 in order to adjust the flight direction of the drone 1, minus a predetermined lag time. The thrust control signal is provided by the control device 6 after the waiting time, and the lagtime makes the change in thrust provided by propeller body 4 at the correct time point in order to obtain a desired flight path. The lag time period may be constant for a particular drone 1 and may be stored in the memory 50 of the control device 7 before use.

[0092] The roll speed determination means may comprise a sensor, such an accelerometer, orientation sensor, or a gyroscope for collecting data that can be used to determine the roll speed. Fig 18 is an example of a read out from a gyroscope that shows orientation during a plurality of rolls. Looking at Fig 18, if an accelerometer is used the read out would be acceleration instead of angular velocity. The roll speed determination means is arranged to determine a roll period of the main body 2 in relation to an external frame of reference. The roll speed determination means may apply any suitable method on data from the sensor. It is preferred that data from a plurality of revolutions, preferably a plurality of consecutive revolutions, of the main body 2 is used to determine the roll speed. For example from 4 to 10 revolutions may be used, but any suitable number of revolutions may be used. Any suitable method including fast Fouriertransform, peak finding or zero crossing, may be used for determining the roll speed using the data from the sensor.

[0093] Hence roll periodsfor a plurality of revolutions of the main body 2 may be used to determine the roll speed. The roll speed determination means may be arranged to determine roll speed is using fast Fourier transform, peak finding or zero crossing, using the plurality of roll periods.

[0094] The roll speed determination means may comprise a sensor arranged to determine a roll period of the main body in relation to an external frame of reference. The sensor may be, for example, an accelerometer or a gyroscope.

[0095] With reference to Fig 19, a method may comprise the steps of 200, determine the roll speed and using the roll speed to determine a the total delay for a desired course change. In step 201 a predetermined lag time period (as data) is received from the memory 50. In step 202, the waiting time is determined by subtracting the predetermined lag time period from the total delay. In step 203, the control device 7 uses the waiting time to initiate a thrust control signal.

[0096] With reference to Fig. 9, The control device 7 comprises a memory 50, processor 51 and a bus 52. The control device 7 may comprise control circuitry. The control device 7 comprises one or more sensors 54, arranged to determine the orientation of the longitudinal axis 3 of the main body 2 in relation to an external frame of reference. Sensor 54 may for example be a gyroscope such as for example a triaxial gyroscope.

[0097] The control device 7 may be configured to carry out the method described in Fig. 10 comprising the steps of 100 determining the orientation of the longitudinal axis 3 of the main body 2 in relation to an external frame of reference and step 101, adjust the rotation speed of the driving means 6 (thrust) in order to adjust the orientation of the longitudinal axis 3.

[0098] In general, although the main body 2 travels first in the figures, the propeller body 4 may also travel first (with respect to the flight direction 21). The driving means 6 may be arranged in the main body 2 or in the propeller body 4. The control device 7 may be arranged in the main body 2 or in the propeller body 4 or distributed between these. In one embodiment, the drive means 6, the control device 7 and the battery 8 are comprised in the main body 2.

[0099] The main body 2 of the drone 1 may have fins 20 that provide flight stability. Fins 20 may also be provided to decrease the speed of rotation of the main body 2. The plane of the fins 20 is generally parallel to the longitudinal axis 3 of the main body 2.

[0100] The flight direction may be any desirable flight direction, such as vertical or horizontal. The drone 1 may be arranged for continuous translation through the air, hence in some embodiments the drone 1 is not arranged to be able to carry out hovering flight.

[0101] The drone 1 may be able to fly with a high speed, such as for example a maximum speed of from 200 km / h to 800m / h such as 100 m / s (360 km / h).

[0102] The weight of the drone 1 may be for example from 100 g to 10 kg, where from 200 g to 1000 g may be preferred or from 200 g to 500 g may be even more preferred. The drone 1 is self-propelled. However, in some embodiments, the drone 1 is launched from a launcher 64 at take-off. The purpose of the launcher 64 may be to achieve a sufficient air speed such that perpendicular force 12 is generated, for example by air flow modification means, or for the drone 1 to achieve stable flight. The launcher 64 may have the shape of a tube from which the drone 1 is launched. The launcher 64 may be powered by for example a catapult, a compressed gas or a chemical propellant. The launcher 64 may be arranged to provide a predetermined kinetic energy to the drone. The launcher 64 may for example be arranged to be hand-held or be arranged to stand on the ground.

[0103] The drone 1 may be able to carry a payload 19. Payload 19 may for example be a chemical sensor. In some embodiments, the drone 1 may be able to hover.

[0104] Drone 1 may be built from standard materials used in the aerospace industry. The fuselage for the main body 2 and the propeller body 4 may for example be built from a polymer material, glass fibre, carbon fiber or metal, such as aluminium. Drone 1 herein may be arranged to attack and destroy a hostile drone with the use of kinetic energy, provided at collision with the hostile drone. The drone 1 may be for single use. The speed (in particular the speed at impact) and weight of the drone 1 may be selected to provide sufficient energy to neutralize the hostile drone at impact, which energy depends on the size or weight of the target. The kinetic energy of the drone 1 during flight may be at least 300 J, preferably at least 1000 J and even more preferably at least 2000 J. In some embodiments the kinetic energy may be from 300 J to 300000 J, more preferably from 1000 J to 10000 J and even more preferably from 1500 J to 5000 J.

[0105] With reference to Figs 20-22 the drone 1 may be provided as a part of system 100 comprising an illumination station 62. Electromagnetic waves are provided as a beam 60 from illumination station 62. The electromagnetic beam 60 may serve as an external frame of reference. A user may use illumination station 62 to provide guidance for the drone 1 towards the target 63, which preferably is a hostile drone. Drone 1 has a guidance sensor 54. The guidance sensor 54 may be provided in the main body 2 of the drone 1. The electromagnetic waves are sensed by the guidance sensor 54 of drone 1, possibly after reflection or scattering by target 63. The beam 60 is preferably provided from outside the drone 1. However, in some embodiments a beam that is reflected or scattered from target 63 may be provided from the drone 1 itself.

[0106] The skilled person knows that there is a plurality of different guidance solutions, including various types of electromagnetic beams 60 and sensors 54 to choose from. The electromagnetic beam 60 may be any type of useful electromagnetic beam such as a laser beam, a radar beam, IR beam or UV beam. The electromagnetic beam 60 may be an optical beam. The beam 60 may comprise a transverse gradient 61 of a property of the electromagnetic waves, such as for example intensity or wavelength.

[0107] The guidance sensor 54 may be arranged to detect a transverse gradient 61 of the electromagnetic beam 60. The sensor 54 may be provided with a lens to focus incoming electromagnetic waves. Dashed lines 61 indicates a transverse gradient 61 of the beam 60. In various embodiments, the electromagnetic waves are reflected or scattered by target 63 and the sensor 54 is arranged to detect the direction to the point with the most intensive electromagnetic waves which are scattered or reflected. In various embodiments the electromatic waves are optical. In various embodiments the electromagnetic beams are laser light. One type of useful guidance solution for system 100 is the laser guidance solution used in the Hellfire missile guidance system.

[0108] With reference to Fig. 21, the guidance sensor 54 may be arranged to be looking generally forward in the longitudinal direction 3 of the main body 2 of the drone 1, and the guidance sensor 54 is then preferably arranged to detect a reflected or scattered beam as seen in Fig. 20. Hence, the sensor 54 may be arranged to detect at least light incoming parallel to the longitudinal axis of the main body 2. Alternatively, the guidance sensor 54 may be backwards looking, looking generally backwards in the longitudinal direction 3 of the main body 2 of the drone 1, and the guidance sensor 54 is then preferably arranged to detect a beam for beam riding (not shown).

[0109] In various embodiments, an illumination station 62 provides illumination on target 63, such that beam 60 is reflected or scattered from the target 63. As an example, the beam 60 may be a laser beam reflected or scattered on the target 63. The guidance sensor 54 may be a forward-looking four-quadrant detector, for example arranged as in Fig. 21. Nose cone 65 is penetrable to the electromagnetic waves of the beam 60.

[0110] Guidance sensor 54 may be specific for the electromagnetic wave provided by illumination station 62. Specificity may be achieved by using for example predefined particular wavelengths and filters, or encryption. Hence the guidance 54 sensor may be arranged to not detect other electromagnetic waves than the electromagnetic waves provided from illumination station 62.

[0111] Launcher 64 may preferably comprise a plurality of drones 1. Launcher 64 may comprise a plurality of essentially upwards directed cylinders that each contain one drone 1. The launcher 64 may have an input means, such as for example a button or a lever, or a wire less device 67 in communication with launcher 64, whereby a user can provide a launch instruction to the launcher 64. The plurality of drones may be automatically launched simultaneously or with a predetermined time interval. Any suitable time interval may be used. The launcher 64 may comprise suitable control circuitry.

[0112] Fig 22 are schematic drawings showing the rotating main body 2 of drone 1 seen from behind, with a guidance beam 60 that optionally has a gradient 61 which enables the drone 1 to find the center of the beam 60, for example with the use of a quad detector as sensor 54 The direction to the target 63 (target direction) is a desired flight direction 22. . The drone 1 is flying towards the target 63.The orientation of the center of mass 16 in relation to the direction of thrust 28 and direction to the target 63 is shown at two timepoints T1 and T2. This drone 1 is, in this example, of the type shown in Figs ll-15a hence the direction of thrust 28 is offset from the center of mass 16 such that pulsing the thrust at time T1 will alter the flight direction of the drone 1 towards the center of the beam 60 indicated by arrow 66. The thrust may be pulsed as long as the center of mass 16 is in subsector 13. At time T2, the longitudinal axis 3 of the drone 1 has moved in relation to the center of the beam 60 and also rotated slightly and the driving means 6 is not pulsed anymore (because pulsing the driving means 6 at this time would move the drone 1 away from the center of beam 60). Instead, control device 7 will have to wait until the drone 1 has rotated so that the driving means 6 may be pulsed again.

[0113] In various embodiments and with reference to Fig. 17, detecting the beam may serve as time point 31 for determining a waiting time. Hence, the orientation may be determined during a first revolution of the main body 2, and the thrust is adjusted during the subsequent revolution of the main body 2. EXAMPLE 1

[0114] To investigate the flight dynamics of a drone, a model of a drone was built.

[0115] The drone had a length of 40 cm. The propeller body was in the rear. The main body had two canards angled at 20°. The main body also had rear stabilizing fins. The configuration of the drone was hence generally similar to the embodiment shown in Fig. 5. The main body comprised a 300 W engine that provided constant thrust. The motor was started, and the model drone was launched by hand to obtain a projectile motion, which subsequently was propelled by the motor. The drone then flew in a stable flight path. It was observed that the main body rotated slower than the propeller body and that that the longitudinal axis of the main body rotated around the direction of flight. The drone was aerodynamically stable.

[0116] EXAMPLE 2

[0117] A bench test was carried out with the drone of example 1 further comprising a control device. The lag time for the control device was estimated to be 4 ms. The roll speed for the main body was 60 Hz, hence the time for one revolution was 1 / 60=16 ms. This enables control of the drive means 4 four times per revolution, providing a sufficient control.

[0118] EXAMPLE 3

[0119] The drone of Example 2 was launched by hand and the drone flew. The propeller body rotated with an rpm of 40 000. The main body rotated 60 times / second.

[0120] It is understood that the present methods and system is partly computer-implemented, using digital computer equipment. The various embodiments and components described herein and communication between these components uses digital computer technology for storing and handling digital information and signals as well as suitable hardware and software, including for example suitable digital processors, digital memories, input means, output means, buses and communications interfaces.

[0121] The methods herein can be implemented with any suitable combination of software and hardware and some suitable combinations of software and hardware are mentioned above.

[0122] Any suitable programming language may be used for the software units and methods described. Data communication may be wireless, or wire bound.

[0123] It is realized that everything which has been described in connection to one embodiment is fully applicable to other embodiments, as compatible. Hence, the invention is not limited to the described embodiments, but can be varied within the scope of the enclosed claims. While the invention has been described with reference to specific exemplary embodiments, the description is in general only intended to illustrate the inventive concept and should not be taken as limiting the scope of the invention. The invention is generally defined by the claims.

Claims

CLAIMS1. An unmanned aerial vehicle, herein referred to as a drone, the drone comprising a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in opposite directions in relation to each other, so that the propeller body provides thrust in the direction of the shaft, where the main body rotates around its longitudinal axis, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other, the drone comprising a control device arranged to control the speed of rotation of the driving means to control the thrust and further arranged to control the flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main body in relation to an external frame of reference, the second rotation speed being referred to as roll speed, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, the drone further configured such that said longitudinal axis continuously rotates around the flight direction of the drone, the flight direction being in relation to the external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis (referred to herein as roll speed), where the control device is arranged to determine the orientation of the longitudinal axis of the main body in relation to the external frame of reference with a frequency that is higher than the roll speed and adjust the thrust during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of attack, thereby adjusting the flight direction of the drone.

2. The drone of claim 1 where the drone has a center of mass and the direction of thrust provided by the propeller body is not directed trough the center of mass of the drone.

3. The drone of claim 2 where the center of mass is in the main body, and where the control device is configured to adjust the thrust when the center of mass is in a position relative to the direction of thrust, such that adjusting the thrust adjusts the orientation of the longitudinal axis of the main body towards a desired flight direction, in relation to the external frame of refence.

4. The drone of claim 2 or 3 where the control device is configured to determine a plane that goes through a desired flight direction and the current flight direction and where the determination of the orientation of the longitudinal axis of the main body involves determining at which point during revolution of the longitudinal axis the direction of thrust is in the plane, and the point during revolution is used to adjust the thrust.

5. The drone of any one of claim 2 to 4 where the shaft is arranged at a fixed angle to the longitudinal axis of the main body.

6. The drone of claim of any one of claims 2 to 5 where the direction of thrust is parallel to the longitudinal axis of the main body.

7. The drone of claim 1 where the angle of the longitudinal axis to the flight direction is caused by an air flow modification surface.

8. The drone of claim 7 where said air flow modification surface is arranged to interact with the air flow over the drone during flight, thereby providing a force in a direction perpendicular to the longitudinal axis of the main body.

9. The drone of claim 8 where the air flow modification surface is a fin or a canard.

10. The drone of claim 9 where the air modification means is a canard which is placed in front of the center of mass of the drone.

11. The drone of claim 1 where the angle of the longitudinal axis to the flight direction is at least partly caused by an air flow modification surface and in addition the drone has a center of mass and the direction of thrust provided by the propeller body is not directed trough the center of mass of the drone.

12. The drone of any one of claims 1 to 11 where the driving means comprises a brushless electrical motor.

13. The drone of any one of claims 1 to 12 to where the control device is configured to use a waiting time, said waiting time defining when, during a complete revolution of the longitudinal axis in relation to an external reference, a thrust control signal should be initiated by the control device.

14. The drone according to claim 13 where the waiting time is determined based on one or more of: current thrust settings, current drone speed, ambient air temperature and air pressure.

15. The drone according to claim 14 where the waiting time is determined based one or more of ambient air temperature and air pressure, and the control device is arranged to, before flight, receive and store data regarding ambient air temperature or ambient air pressure, and to use the data during flight to determine the waiting time.

16. The drone of any one of claims 13 to 15 where the control device comprises roll speed determination means arranged to determine the roll speed and where the control device is configured to use the roll speed to determine the waiting time.

17. The drone of any one of claims 13 to 16 where the waiting time is determined as the time from a time point when the orientation of the longitudinal axis, or the position of the drone, in relation to an external frame of reference is determined, until the change in thrust should be provided by the propeller body in order to adjust the flight direction of the drone, minus a predetermined lag time.

18. The drone of any one of claims 1 to 17 where the control device is arranged to adjust the thrust during a subsection of a first complete revolution of the main body and again adjust the thrust during a subsection of a second complete revolution of the main body, the second revolution being the revolution after the first revolution.

19. The drone according to claim 1 to 18 wherein the control device is further configured to: determine the orientation of the longitudinal axis of the main body in relation to a target direction in the external frame of reference using a guidance sensor, and where the target direction is provided by an external source of electromagnetic waves, the control device being configured to determine the orientation of the longitudinal axis of the main body of the drone in relation to the target direction.

20. The drone according to claim 19 wherein the electromagnetic waves is a laser beam and the guidance sensor is a laser sensor.

21. The drone according to any one of claims 1 to 20 being configured to have a kinetic energy of from 1000 J to 10000 J during flight.

2. A method in an unmanned aerial vehicle herein referred to as a drone the drone comprising a main body which is elongated and having a longitudinal axis, the main body being rotatable attached at one end of the elongated body to a propeller body with a shaft so that the main body and the propeller body are arranged to rotate in opposite directions in relation to each other, where the main body rotates around its longitudinal axis, so that the propeller body provides thrust in the direction of the shaft, the drone comprising driving means mechanically connected to the shaft, the driving means driving rotation of the bodies in relation to each other the drone comprising a control device arranged to control the speed of rotation of the driving means to control the thrust and further arranged to control the flight direction of the drone, where the drone is configured to rotate the propeller body at a first rotation speed that is greater than a second rotation speed of the main in relation to an external frame of reference, the second rotation speed being referred to as roll speed, where the drone is configured such that the longitudinal axis of the main body has, during flight, an angle of attack greater than zero to the flight direction of the drone, the drone further configured such that said longitudinal axis continuously rotating around the flight direction of the drone, the flight direction being in relation to an external frame of reference, where the rotation around the flight direction occurs with the same angular speed as the main body rolls around the longitudinal axis, the method comprising, determining the orientation of the longitudinal axis of the main body in relation to an external frame of reference with a frequency that is higher than the roll speed , andadjusting the thrust during a subsection of a complete revolution of the main body in relation to the external frame of reference in order to adjust the angle of attack, thereby adjusting the flight direction of the drone.

23. The method of claim 22 where the control device uses a waiting time, said waiting time defining when, during a complete revolution of the longitudinal axis in relation to the external reference, a thrust control signal should be initiated.

24. A system comprising a drone according to any one of claims 1 to 21, the system further comprising a launcher.

25. The system of claim 24 where the launcher comprises a plurality of drones.

26. The system according to claim 24 or 25 further comprising an illumination means, the illumination means arranged to provide electromagnetic waves configured to be detected by a guidance sensor of the drone.

27. The system of claim 26 where the illumination means is arranged to provide a beam that is configured to be reflected or scattered by a target to provide guidance of the drone to the target.

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