GB2538827A

GB2538827A - Aerial vehicle with fender cage rotatable about two perpendicular axis

Info

Publication number: GB2538827A
Application number: GB1601265.0A
Authority: GB
Inventors: Norman Macdonald Andrew
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-05-26
Filing date: 2016-01-25
Publication date: 2016-11-30
Also published as: GB201601265D0; GB201508995D0

Abstract

An aerial vehicle has a lift assembly and a fender cage that can rotate about two mutually perpendicular axes. The fender cage is supported by an endless annular track 14 in which a rotary bearing is engaged that connects the lift assembly to the track. This permits rotation of the lift assembly about axis L. The fender cage has opposing hubs 15. Within these are rotary bearings that allow the fender cage to rotate about a second axis H, perpendicular to the first. If the aerial vehicle is involved in a collision it should not be cause to tumble in an uncontrolled manner. The present invention is relatively less complex to assemble, has fewer components and may be fabricated with an improved strength to weight ratio than prior art.

Description

Aerial Vehicle With Fender Cage Rotatable About Two Perpendicular Axes

Technical Field

[001J The invention concerns an aerial vehicle which will generate lift thrust directly from motors which will usually be provided by one or more vertical axis rotors (eg., propellers or ducted fans), but may include other moving wing thrusters such as an ornithopter or non-wing thrusters such as jets or rockets. The aerial vehicle may be either unpiloted (UAV) or remotely piloted (RAV) and for the sake of brevity will be referred to herein as an aerial aerial vehicle. The aerial aerial vehicle of the invention is intended primarily as a toy, but may have a range of other applications including search and inspection, particularly in confined environments.

Prior Art

10021 Moving wing aerial drones consist of a chassis supporting one or more motors, an onboard controller and a power supply which may be referred to collectively in this specification as the lift assembly. The motors will be configurable to generate lift directly by exhausting downwardly. Most commonly a motor is arranged to generate lift by spinning a propeller (rotor) about a substantially vertical axis. In some aerial drones a single vertical axis rotor may be employed and the rotary axis tilted from the vertical to generate thrust in a horizontal direction. To counter the effect of rotor torque a horizontal axis rotor may be used. However, it is now common for drones to employ multiple counter rotating rotors, for example two or four to counter the effect of torque. Rotors may be mounted on concentric axis or on multiple spaced axes. Any or all of: the sense of rotation (clockwise or counter clockwise), relative speed and attitude of each rotor may be controlled to control the aerial vehicle pitch, roll, yaw, airspeed and altitude.

[3] Controllers are commonly responsive to wireless control signals generated from a remote, manually operable control console. To minimise the skill required of an operator an onboard controller runs a control algorithm to manage the individual motor rotation speed and attitude in response to gross control instructions defining direction, airspeed, altitude (up or down) and horizontal direction (forward, back, left or right) and feedback from an onboard sensor array. Although toy drones tend to be light weight and rarely carry more payload than a small camera, deliberate or accidental misuse can result in collision causing damage to the aerial vehicle and injury to ambient structures or persons. The larger an aerial vehicle gets, the greater is the potential for injury. Operation of the aerial vehicle in confined spaces or where unexpected changes of air current occur can provoke collisions with nearby fixed structures. Such collisions may damage the aerial vehicle or the structure and/or cause the aerial vehicle to fall or recoil in an uncontrolled hazardous manner.

[4] In an effort to alleviate the risk of injury designers have begun enclosing drones in a drum shaped fender cage as disclosed in perspective view in figure 1.1 and in section in figure 1.2. Further details of this type of aerial vehicle are disclosed in US2014/0131507 Al. The aerial vehicle in figures 1.1 and 1.2 comprises a chassis with a ring 1, a pair of spokes 2 each extending radially in towards the centre of the ring 1, and a pair of spokes 3 extending radially out from the ring 1. The inwardly extending spokes support a housing 4. The housing 4 may incorporate a controller, power cells and wireless communication system (not shown). The ring also supports four equiangularly spaced rotors 5, each comprising a vertical axis rotor blade 6 and, a motor and housing 7.

[005] The outer spokes 3 support a barrel shaped cage 8 formed from a number of elongate rigid members connected at nodes. The spokes all lie on a longitudinal axis (L). Each of spokes 3 engages the elongate cylindrical cage 8 at a cage hub 9 which accommodates a bearing 10 to enable the cage to rotate around the longitudinal axis corresponding to the long axis of the outer spokes 3. The aerial vehicle also has a vertical axis (V) and a lateral axis (H). The cage consists of a framework so that the blades 6 cannot collide with a substantial external object. The cage 8 comprises endless ring members centered on the hubs to which they are connected via arcuate spoke members. The endless ring members mounted to longitudinally opposite hubs are connected via longitudinal members. The aerial vehicle can be flown to roll up a surface such as a wall or along a ceiling or floor so long as the long axis (L) is parallel to the surface and movement is perpendicular to the long axis. However, if the aerial vehicle collides with an object while moving in any direction not sufficiently perpendicular to the long axis it may be caused to tumble in an uncontrolled manner. Figures Sand 6 of US2014/0131507 Al disclose an aerial vehicle similar to that described above but having a spherical cage. If the aerial vehicle is induced to tumble the aerial vehicle can only recover by the control driving the motors to rectify the tumbling motion. Because of the inertia of the cage this puts increased demands on the controller and rotors.

[006J Flyability SA have sought to alleviate the problem mentioned in the preceding paragraph by means of the "Gimbal! TM" aerial vehicle which can be found at http://www.flyabiiity.com/productl. The prior art Flyability aerial vehicle is reproduced at figures 2.1 and 2.2 which show a gimbal between the aerial vehicle chassis/motor/controller (CMC) assembly and a generally spherical cage such that the cage can rotate in any direction relative to the CMC assembly enabling the CMC assembly to remain substantially vertical. In figures 2.1 and 2.2 integers common to the prior art of figures 1.1 and 1.2 are similarly numbered. The prior art of figures 2 differs from that of figures 1 in that the single rotor 5' provides counter rotating coaxial blades 6' and 6" and is integrated with the CMC. The inner spokes 2 rigidly connect the housing to the ring 1. Unlike the prior art of figure 1 the ring 1 is freely rotatably connected to a gimbal ring 11 by rotary bearings 12 disposed on the longitudinal axis (L). The gimbal ring 11 is freely rotatably connected to a cage 8' via rotary bearings 13 which act on any axis perpendicular to the longitudinal axis, as shown this is the vertical axis V-V. The cage 8' is formed from a mesh of substantially rigid straight struts connected to each other at nodes, where the nodes are all sited on a notional sphere. The polyhedral shape thus created can therefore roll readily in any rotary direction around the housing 4 and rotors 6 and does not restrict airflow across the rotors. This "Gimbal!" aerial vehicle thus alleviates the technical problems explained with reference to figure 1 in that the cage can move in any direction against a surface without applying significant torque to the housing and lift assembly 4, 6 and minimises the risk of destabilising flight. However, the "Gimbal!" requires a cage which is complex to fabricate, requires the extra gimbal ring 11 and two additional rotary bearings 13. In addition to extra steps in fabrication this makes the "Gimball" heavy, reducing its payload and/or range and/or requiring fabrication from high strength to weight ratio and therefore expensive materials which are often difficult and therefor expensive to work with.

[007] It is an object of the present invention to provide an aerial vehicle with collision stability characteristics similar to those of the "Gimball" having a structure which may be relatively less complex to assemble, has fewer components and may be fabricated with an improved strength to weight ration.

Statement of Invention

[OM Accordingly the present invention provides a moving wing aerial aerial vehicle with a fender cage: a lift assembly, an endless annular track, a rotary bearing engaged with the endless annular track to slide around the track and support the fender cage whereby the fender cage can rotate about two mutually perpendicular axes extending through the lift assembly.

[0091 The track may form an integral part of the cage. In this case spokes may extend from the lift assembly to engage with the rotary bearing. The rotary bearing may engage directly with a slider received into a groove in the track.

/o/o/ Resilient means such as a compression coil spring may be arranged to urge the bearing into engagement with the track. The bearing may comprise one or more rolling elements.

[11] The track is provided by a cage member in the form of an endless ring. The cage member may provide the track by means of a channel. The channel may be provided by a member having a "U" shaped cross section.

[12] In a second embodiment of the aerial aerial vehicle the endless annular track is provided by a ring extending around the lift assembly. A slider engages in the track to be movable around the track. A spoke extends radially from the track to engage with a bearing mounted in the fender cage. This arrangement helps to reduce the weight of the annular track and the overall weight of the aerial vehicle without adversely affecting the stiffness or strength of the assembled aerial vehicle.

[13] In an alternative variant of the second embodiment the rotary bearing may be mounted in the slider so that the spoke and fender cage can rotate relative to the slider.

[0141 The cage is preferably formed from arcuate members which may all have a common radius of curvature corresponding to the radius of a notional sphere such that when assembled into the cage the cage members lie in, or on, the surface of the sphere.

[15] The lift assembly may include each rotor, power supply, onboard controller wireless communication system and a supporting chassis. The lift assembly may also provide a platform for any payload such as a camera.

[16] In the second embodiment the annular track is immovably oriented with respect to the axis of the or each rotor. For example the annular track may be oriented to have a central axis perpendicular to the rotor axis.

[017J The annular track may include features to facilitate movement of the slider such as low friction bearing surface, or the slider may include such features. For example the track may include rolling elements, or the slider may incorporate rolling elements. The slider may extend circumferentially around the annular track by a distance greater than the width of the track. Preferably the aspect ratio of the slider width to circumferential extent will be 1:6 or more.

Brief Description of Figures

[0181 Embodiments of a moving wing aerial aerial vehicle with a fender cage rotatable about two perpendicular axes constructed in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying illustrative figures; in which, Figure 3.1 is an isometric SE view of a first embodiment; Figure 3.1.1. is an enlarged perspective fragmental detail view of the bearing from figure 3.1; Figure 3.2 is a front sectional elevation of the first embodiment; Figure 3.2.1 is a sectional elevation in the view line 3.2.1 in figure 3.2; and Figure 3.2.2 is a sectional elevation on the view line 3.2.2 in figure 3.2; Figure 4A is an isometric SE view of a second embodiment; Figure 4B is a sectional front elevation of the second embodiment without the rotors; Figure 4C is a fragmentary detail sectional view from figure 4B; and Figure 4D is an exploded SE isometric of the aerial vehicle with the rotors and fender cage omitted.

S

Detailed Description of Figures

10191 The aerial aerial vehicle illustrated by the figures has a lift assembly comprising a chassis, a housing 4 and four rotors 5. The chassis comprises a substantially rigid ring 1, a pair of inner spokes 2 which extend towards the centre of the ring to support the housing 4, and a pair of outer spokes 3 which extend radially out from the ring 1. The housing 4 is conventional and houses a power supply, onboard controller and wireless communication system connected via communication lines to each rotor 5. The four rotors 5 are mounted equiangularly spaced around the ring 1 with the axis of each blade 6 parallel to the vertical axis V-V of the aerial vehicle.

[20] The cage 8 is formed from: a track ring 14, a pair of hubs 15; three major rings 16; and two minor rings 17. The axially opposed hub structures 15 are each attached to the track ring 14 and disposed in axially opposing positions. The track ring 16 may be formed from plastics by moulding, with the hubs 15 being an integrally moulded part of the track ring 14. To minimise the weight of the track ring 14 it may be formed with a outer web 18 supporting angularly spaced flanges 19. Each angularly spaced flange 19 extends radially inwardly from an edge of the outer web 18 to support an endless retaining rail 20 forming a guide channel providing the track to constrain the bearing 10. The web 18 may also include vacant regions to further minimise weight.

[21] Each of the three major rings 16 is attached to each of the hubs 15 at intervals to be angularly spaced from the track member 18 and each other.

[022J. Each of the major rings 16 is fed through a complementary sectioned hole formed in each minor ring 17 to secure the minor rings 17 to the major rings 16. Each of the major rings 16 is secured into corresponding holes formed in each hub 15. The track ring 14 is secured to each minor ring 17 by means of features moulded onto the track ring 14 which engage with the section of minor ring 17.

[023J Each outer spoke 3 comprises a tubular member 21 telescopically received into a corresponding tubular inner spoke 2. Each outer spoke is sleeved onto a connecting spring rod 22 which extends diametrically across the centre of the ring 1 and supports a coil spring 23 so that the coil spring bears against the outer spokes 3 and urges them radially outwards. The outer ends of each outer spoke support a cup shaped cylindrical bearing housing 24. A rolling element or ball bearing 25 is retained in the bearing housing 24. Thus when assembled the spring 23 presses the bearing housing 24 and ball bearing 25 into the track formed by the web 18 and rails 20.

[0247 In use the cage 8 can freely rotate in any direction around the lift assembly without transmitting significant torque to the lift assembly and disrupting the overall stability of aerial vehicle.

[025] Referring to figures 4A-4C the aerial vehicle comprises a lift assembly having a housing 104 housing and four rotors 105. The housing houses a power supply (usually electrochemical cells), an onboard controller and wireless communication system connected via communication lines to each of the four rotors 105. Each rotor 105 is supported on one of four cantilevers 106 extending from the housing 104. Each cantilever 106 extends radially from a vertical axis, equiangularly spaced and lying in a common, horizontal plane. Each rotary axis of each rotor is situated at a similar rotor radius from a central vertical axis 'V" of the aerial vehicle.

[026J The housing 104 supports a diametrically extending spoke 107 extending through a centre of the aerial vehicle. The spoke 107 supports an integrally formed annular track 108. The annular track 108 is concentric with the aerial vehicle centre through which the vertical axis and a lateral rotary axis L-L pass. Thus the annular track moves (rotates, pitches and yaws) with the housing 104.

[027.1 The annular track 108 consists of a ring 109 into which are formed four circumferentially extending equiangularly spaced slots 110. The side walls of each slot are perforated by a plurality of spaced holes 111 extending in the circumferential direction of the slot and spaced to receive an axle of a rolling element 112. The annular track is captured in a track rotor 113. Track rotor 113 comprises a first ring 114 and a second ring 115. The first and second rings have inner and outer radii such that they span the annular track 108. A plurality of axially extending tongues 116 extend from the outer periphery of the first ring 114. Each tongue 116 is circumferentially extending and circumferentially spaced from the other tongues. Each tongue terminates in a barb formation 117. The tongue 116 extends axially to an extent sufficient that when the first ring is brought up to one side of the annular track 108, and the second ring is brought up to the opposite side of the annular track 108, each tongue engages in a corresponding circular slot 118 formed in the periphery of the second ring 115 and is trapped by the barb 17. Thus the annular track 108 is caged by the track rotor 113. The tongues 116 have internal surfaces which bear on the rolling elements 112 and the span of the tongues is such that the track rotor 113 can rotate freely around the annular track 108.

[0217J Two of the tongues 116A provide mounting points for each of two outer spokes 118 which extend radially away from the aerial vehicle axis and each terminate in a rotary bearing 119. Each rotary bearing 119 is adapted to be received into a bearing housing 120 formed in the cage hub 15 so that each outer spoke 118 can rotate around its long axis.

[029.1 In addition to the cage hub 15 the fender cage has four longitudinally extending minor rings 121 spaced along the lateral axis "L" each of which is joined by four major rings 122 which radiate from each hub and are joined to each minor ring 121 at a node.

[030J The assembly of the aerial vehicle thus comprises assembling the annular track 108 with the track rotor 113. Installing the control components and battery into the housing 104 and attaching the housing to the inner spoke 107. Attaching the rotors 105 to the cantilevers 106. Sleeving each hub 15 onto the ends of the outer spokes 118 and retaining the outer spokes 118 in each hub 15 by means of the bearings 119 engaged into the bearing housings 120. The six major rings 122 are formed by sleeving the resilient elongate members through nodes having a sleeve 123 and a saddle 124 to engage with each hub 15. Then the minor rings 121 are snapped into the node saddles124 to form a rigid fender cage.

[031] The resulting aerial vehicle of the second embodiment is relatively lighter than the first embodiment.

Claims

Claims 1. A moving wing aerial aerial vehicle with a fender cage: a lift assembly, an endless annular track, a rotary bearing engaged with the endless annular track to slide around the track and support the fender cage whereby the fender cage can rotate about two mutually perpendicular axes extending through the lift assembly.
2. An aerial vehicle according to claim 1 wherein the lift assembly is connected to the cage via a bearing, wherein the track is an integral part of the cage, and said bearing is urged to engage in and constrained to travel around the endless annular track.
3. An aerial vehicle according to claim 2 wherein the annular track is formed in a channel section member having the open end of the member facing the lift assembly.
4. An aerial vehicle according to claim 3 wherein the bearing is supported on an end of a spoke urged outwardly away from the lift assembly to be pressed into the track.
5. An aerial vehicle according to claim 4 wherein the spoke is urged outwardly by a coil spring.
6. An aerial vehicle according to claim 4 or 5 wherein the bearing is a rolling element bearing arranged to roll circumferentially along the track to allow the cage to rotate around a first axis and to allow the cage to spin around a second axis extending through the centre of the rolling element and perpendicular to the first axis.
7. An aerial vehicle according to any one of the preceding claims wherein the annular track forms an integral part of the cage.
8. An aerial vehicle according to claim 7 wherein the cage is formed from three major ring members and each major ring member is connected to a pair of hubs, and each minor ring member is connected to each major ring member.
9. An aerial vehicle according to any one of the preceding claims wherein the lift assembly provides at least one vertical axis rotor operable to generate lift thrust.
10. An aerial vehicle according to claim 1 and as herein described with reference to figures 3.
11. An aerial vehicle according to claim 1 wherein the endless annular track is formed from a track ring and a rotor ring.
12. An aerial vehicle according to claim 11 wherein the track ring is rigidly engaged with the lift assembly.
13. An aerial vehicle according to claim 11 or claim 12 wherein the rotor ring envelopes the track ring to be freely rotatable around the track ring.
14. An aerial vehicle according to claim 13 wherein rolling elements act between the track ring and rotor ring.
15. An aerial vehicle according to any one of claims 11 to 14 wherein an outer spoke extends from the rotor ring to a hub of the fender cage.
16. An aerial vehicle according to claim 15 wherein the outer spoke engages the hub of the fender cage by means of a rotary bearing.
17. An aerial vehicle according to any one of claims 11 to 16 wherein lift assembly comprises four rotors each disposed on a cantilever extending radially from the vertical axis of the aerial vehicle in a plane perpendicular to the vertical axis.
18. An aerial vehicle according to claim 17 wherein the annular track is supported in a plane intersecting the vertical axis.
19. An aerial vehicle according to any one of claims 11 to 18 and as herein described with reference to figures 4.