GB2586955A

GB2586955A - Drone apparatus

Info

Publication number: GB2586955A
Application number: GB1910451.2A
Authority: GB
Inventors: Cary Selby; Mcdonald Michael; Gault Craig
Original assignee: Casta Spes Tech Ltd
Current assignee: Casta Spes Tech Ltd
Priority date: 2019-07-22
Filing date: 2019-07-22
Publication date: 2021-03-17
Also published as: GB201910451D0

Abstract

A ground-based drone 1 has two wheels 2, a support arrangement 3 to support the wheels and a drive arrangement 4. The drive arrangement is disposed within at least one of the wheels and engages the respective inner rim of the wheel to rotate of the wheel. The drive mechanism may include a geared toothed arrangement (27 fig.10) and may be a direct or indirect drive arrangement possibly including a transmission. The drone has a centre of mass (CoM) offset from an axis of rotation A of the wheels, the CoM providing a counterbalance acting to maintain the drone in an upright configuration. The CoM may be below the axis of rotation A and the drone may carry a load such as a sensor or imaging device. The drone may incorporate a passive roll recovery arrangement that incorporates dome shaped members 8 which may help to self-right the drone following a roll, figs 12-14.

Description

DRONE APPARATUS

FIELD

This relates to a ground-based drone apparatus. In particular, this relates to a two-wheeled robotic device.

BACKGROUND

Autonomous or semi-autonomous robotic vehicles, commonly known as drones, have undergone significant advances in recent years. However, despite the advances, there remain a number of significant barriers to the use of drones in a variety of applications.

Control of conventional aerial drones is highly complex and there have been a number of reported incidents involving collisions or near misses between drones and aircraft or other vehicles and structures, which has resulted in proposals for increased restrictions on the use of aerial drones in certain areas.

The use of aerial drones is also greatly affected by weather conditions, with aerial drones typically unable to operate effectively in high winds or other inclement weather conditions.

The operational use of drones is also limited by the onboard power supply. This is particularly prevalent in aerial drones where performance of the drone is often compromised by the weight of onboard batteries. Similarly, the ability of an aerial drone to carry a payload is affected by the power to weight ratio of the device, thereby reducing flight time with increased weight.

One common application for drones is to provide a mount for a camera, since drones provide a cost effective and flexible alternative to other means of aerial photography. However, conventional aerial drones are often unable to fly safely near to ground level, such as under covered areas, and/or navigate obstacles, such as tree branches. Such obstacles make conventional aerial drones unsuitable for ground-based or near ground-based applications.

SUMMARY

According to a first aspect there is provided a ground-based drone apparatus, comprising: two wheels a support arrangement interposed between and configured to support the wheels thereon, a drive arrangement disposed within at least one of the wheels, the drive arrangement configured to engage a rim of the wheel to drive rotation of the wheel; and wherein the apparatus has a centre of mass offset from an axis of rotation of the at least two wheels, the centre of mass providing a counterbalance acting to maintain the apparatus in an upright configuration, thereby providing a passive balancing arrangement of the apparatus.

The apparatus may take the form of a robotic wheeled apparatus, and in particular but not exclusively, a self-stabilising robotic wheeled apparatus.

Embodiments of the apparatus provide a number of benefits over conventional drones. For example, the provision of a ground-based drone apparatus permits use of the apparatus under covered areas and/or in terrain where conventional aerial drones are unable to operate. The provision of a ground-based drone apparatus also obviates the requirement for the apparatus to lift its own power pack as in conventional aerial drones, permitting greater operational life to be achieved. Moreover, embodiments of the apparatus provide increased performance without restricting the range or functionality of the apparatus. It will be recognised that the apparatus may be utilised in a wide variety of applications. For example, the apparatus may be utilised for the transportation of goods or equipment; may be utilised in military operations for investigative missions; and/or may be used as a recreational apparatus or toy.

Embodiments of the apparatus find particular utility in security applications, such as perimeter security, where the use of conventional aerial drones is restricted due to safety concerns, weather and/or climate issues, for example, during storms.

As described above, the apparatus has a centre of mass offset from an axis of rotation of the at least two wheels, the centre of mass providing a counterbalance acting to maintain the apparatus in an upright configuration.

The apparatus may be configured with the centre of mass below the axis of rotation of the at least two wheels.

The apparatus may utilise the centre of mass of the apparatus as a counterbalance to the load carried by the apparatus, which may be located above the axis of rotation of the wheels.

The apparatus may comprise a mass disposed below the axis of rotation of the wheels.

In particular embodiments, the mass may comprise or take the form of an onboard power supply of the apparatus, such as a battery pack or the like.

The mass may be disposed on, or supported by the support arrangement of the apparatus.

The centre of mass of the apparatus may be disposed offset from the axis of rotation of the apparatus. By such provision, the orientation of the apparatus will naturally and passively be biased towards a position in which the centre of mass is directly vertically below the axis of rotation of the apparatus, when in use, without active input from an operator, or control system.

Beneficially, the apparatus may be inherently stable and may be configured to return to an equilibrium from any angle, the apparatus employing a passive balancing and/or self-righting system in which the stability of the apparatus is maintained without proactive and/or reactive control. This in turn obviates the requirement for complex control systems, and associated equipment which reduce performance.

The apparatus may comprise a roll recovery arrangement.

The roll recovery arrangement may comprise a passive roll recovery arrangement.

The roll recovery arrangement may comprise one or more dome-shaped members.

The dome-shaped members may comprise or take the form of elliptical dome-shaped members.

The roll recovery arrangement may be configured to prevent the apparatus from being displaced into a position that may otherwise be unrecoverable, for example with the wheels substantially parallel to the ground. The roll recovery arrangement may provide a further advantage of protecting the internal components, for example the drive arrangement, batteries, and drive wheels. Alternatively or additionally, the roll recovery arrangement can also reduce or prevent in the ingress of water or debris, e.g. sand, dust, small rocks or the like.

The roll recovery arrangement, e.g. dome-shaped members, may be disposed on, attached to or formed as part of the wheels.

The dome-shaped members may comprise an arcuate, hemi-spherical or substantially hemi-spherical shape or profile. The dome-shaped members may comprise a compressed hemi-spherical or hemi-ellipsoid shape or profile.

The roll recovery arrangement may comprise a central axis which may be coincident with the axis of rotation of the at least two wheels.

The central axis of the roll recovery arrangement may be offset from the centre of mass of the apparatus.

The roll recovery arrangement may be configured to assist the stability and/or maintenance of the apparatus in an upright orientation, the roll recovery arrangement.

passively biasing the apparatus to an unstable position wherein the location of the centre of mass is offset from the axis of rotation of the wheels and thus applies a moment force onto the apparatus, causing the apparatus to reposition into a stable orientation with all of the at least two wheels engaged with the ground surface. Such a stabilisation action may act in a passive manner, with no proactive or reactive control required from a control system and/or an operator. By such provision, the apparatus is

inherently stable.

The dome-shaped members may be formed of a suitable high strength, high rigidity material, such as metal, alloy, composite, plastic materials or the like.

As described above, the apparatus comprises two wheels.

In particular embodiments, the apparatus comprises two wheels only.

However, the apparatus may alternatively comprise more than two wheels, for example three, four, five or more wheels.

At least one of the wheels may comprise an inflatable tyre.

Alternatively or additionally, at least one of the wheels comprises a solid tyre and/or at least one of the wheels takes the form of a solid wheel. By such provision, the likelihood of puncture is reduced.

The tyre may be disposed on the rim, that is on an outer surface of the rim which may be profiled to receive the tyre.

In particular embodiments, the wheels comprise one or more bicycle wheels.

Alternatively or additionally, one or more of the wheels may be of solid construction.

As described above, the drive arrangement is disposed within at least one of the wheels, the drive arrangement configured to engage an inner surface of the rim ("inner rim") of the wheel to drive rotation of the wheel.

The drive arrangement may comprise a rotary drive.

The rotary drive may comprise a motor.

The motor may comprise an electric motor.

The motor may comprise a DC electric motor, such as a brushless DC electric motor.

The drive arrangement may comprise one or more drive wheel configured to engage the wheel, in particular the rim.

The drive wheel may be configured to engage the wheel via a friction fit. Alternatively or additionally, the drive wheel may comprise a profile configured to engage the wheel.

The inner rim of the wheel may comprise a profile.

The drive wheel profile may be configured to engage with the profile disposed or formed on the inner rim of the wheel.

The profile of the drive wheel may comprise or take the form of a female profile. The profile of the drive wheel may comprise, or take the form of a V-shape, U-shape, rectangular shape or other suitable profile.

Alternatively, the profile of the drive wheel may comprise or take the form of a male profile.

The profile of the drive wheel may comprise, or take the form of a V-shape, U-shape, rectangular shape protrusion or other suitable profile.

The profile of the inner rim of the wheel may comprise or take the form of a male profile.

The profile of the inner rim of the wheel may comprise, or take the form of a V-shape, U-shape, rectangular shape protrusion or other suitable profile.

Alternatively, the profile of the inner rim of the wheel may comprise or take the form of a female profile.

The profile of the inner rim of the wheel may comprise, or take the form of a V-shape, U-shape, rectangular shape or other suitable profile.

Alternatively or additionally, the drive wheel may comprise a toothed and/or geared arrangement, which may be configured to engage with a toothed and/or geared arrangement disposed on the inner rim of the wheel.

The drive arrangement may comprise a plurality of drive wheels, each configured to engage the wheel.

The drive arrangement may directly drive the wheel.

Alternatively, the drive arrangement may indirectly drive the wheel.

The drive arrangement may comprise a transmission system coupled between the rotary drive and the one or more drive wheel.

The transmission system of the drive arrangement may comprise a pulley drive arrangement.

The pulley drive arrangement may comprise one or more active pulley assemblies, that is, one or more pulley assembly which is actively driven to drive rotation of the wheel. The pulley drive arrangement may comprise one or more passive pulley assemblies, that is, one or more pulley assembly which is not actively driven to drive rotation of the wheel, i.e. is free moving, free to rotate or free-wheel. The pulley drive arrangement may engage with the toothed and/or geared arrangement on the inner rim of one or more wheel. By such provision, the pulley drive arrangement may act, form or be a planetary and/or an epicyclic gear arrangement.

The wheels may be independently operable. For example, the drive arrangement may be configured to drive the wheels at equal speeds and/or the wheels may be driven and/or controlled independently. One of the wheels may be driven at a different speed to the other of the wheels.

One of the wheels may be driven in a different rotational direction to the other of the wheels.

By such provision the apparatus may be turned or steered by operating at a different velocity, or direction, thereby creating a yawing motion, referred to as differential steering.

Beneficially, the drive arrangement permits the apparatus to be propelled at speeds of up to for example, lOmph, or up to 15mph, or up to 20mph, or up to 30mph, or greater than 30mph.

The apparatus may comprise a braking system.

The braking system may comprise hydraulic, electromagnetic, servo or mechanical control. The braking system may comprise one or more brake. The brake or brakes may comprise disc brakes, drum brakes, rim brakes or the like.

One or more of the wheels may be fitted with One or more brake may be fitted to one or more wheel.

The drive arrangement may comprise an onboard power supply.

The power supply may supply power to at least one of the motor, onboard electrical components, electronic controller for controlling the speed and/or orientation of the apparatus, and/or for receiving control data from an operator. The power supply may be or may comprise at least one battery. The at least one power supply may be disposed on, or supported by the supporting frame of the drive arrangement. Alternatively or additionally, the power supply may comprise an internal combustion engine, hydrogen fuel cell or the like.

The power supply and/or batteries may form at least part of the passive balancing arrangement.

The device may comprise at least one cross beam, which may provide structural integrity and/or rigidity to the structure. The at least one cross beam may provide a central chassis for the device, onto which other components may be connected, attached or disposed. The cross beam may comprise a horizontally disposed strut, beam, bar or the like.

The cross beam may be located above the axis of rotation of the at least two wheels. The cross beam may form the component located closest to the centre of mass of the apparatus. For example, the cross beam may form the lowest point of the apparatus excluding the wheels. By such provision, the ground clearance of the device is defined by the position of the crossbeam relative to the axis of rotation of the apparatus and/or the position of the rims of the at least two wheels.

The apparatus may be configured to have a ground clearance of, for example, less than 50mm, or at least 50mm, or at least 100mm, or at least 200mm, or at least 300mm, or at least 400mm, or at least 500mm, or at least 1000mm.

The apparatus may comprise a vertical pole, pillar, beam or the like which may be connected to, or disposed on the device, for example, on the cross beam. The vertical pole, pillar, beam or the like may extend perpendicularly from the cross beam and/or may be configured to be in a vertical orientation when in use. The vertical pole, pillar, beam or the like may be telescopic, i.e. may be extendable and/or collapsible.

The vertical pole, pillar, beam or the like may be repositionable, i.e. the angle of the pole relative to the cross beam may be variable. The angle of the pole may be remotely controlled, and, for example, may be adjustable whilst in use.

The apparatus may comprise a sensing and/or imaging device.

The sensing and/or imaging device may be disposed on the pole, pillar, beam or the like, for example, on the top of the pole, pillar, beam or the like. By such provision, the sensing and/or imaging device may be disposed at an elevated position relative to the wheels of the device.

Alternatively or additionally, the sensing and/or imaging device may be disposed on or within one or more of the wheels.

The sensing and/or imaging device may comprise at least one camera. The at least one camera may be a video camera. The at least one camera may employ multi-spectral or enhanced spectral imagining such as infrared (thermal imaging), or ultraviolet-imaging, or night vision or image intensification.

Additionally or alternatively, the sensing and/or imaging device may comprise other sensing devices such as, temperature sensors, proximity sensors, radar, sonar, LiDAR or the like.

The apparatus may comprise at least one light source. The at least one light source may be disposed on the pole, pillar, beam or the like, and/or may be disposed on other components of the drive, for example, the cross beam, wheels, pole etc. The lights may comprise LED lights, halogen bulbs or the like.

The sensing and/or imaging device may be disposed offset from the axis of rotation of the at least two wheels; thereby aiding the balancing of the device and wherein the sensing and/or imaging device may act as a counterbalance for the device.

As such, the optimal equilibrium may be achieved with the batteries and/or counterweight disposed at a side of the wheels opposite the vertical pole, i.e. at the bottom of the wheels, and the camera in an upright position.

The sensing and/or imaging device may be disposed offset from the centre of mass of the device. The pivot point of the apparatus and/or sensing and/or imaging device may be interposed between the sensing and/or imaging device and the centre of mass of the apparatus. By such provision the sensing and/or imaging device may act as a counter balance, and/or may aid balancing and/or stabilisation of the device. Separating the sensing and/or imaging device from the centre of mass of the device in this manner mechanically isolates the sensing and/or imaging device and the movement of the device, thereby allowing for smooth movement of the sensing and/or imaging device, and thus, for example, minimises camera shake even when the apparatus moves over an uneven surface.

The apparatus may comprise an autonomous navigation and/or control system. Alternatively or additionally, the apparatus may comprise a semi-autonomous or a manual navigation and/or control system.

The apparatus may comprise an autonomous control system and may comprise a manual override which may be initiated at the request of an operator.

By such provision, the apparatus may operate in an autonomous manner for certain use, for example, routine surveillance, and an operator may initiate a manual override, allowing the operate to temporarily take full, or part control of the device for specific applications, for example, for highly complex manoeuvres, or to target a particular location. Autonomous control may be reinstated by the request of the operator. The autonomous system may allow the apparatus to operate without human control, for example using a sonar system, or other means of audio or visual detection and a feed-back control, or by simply performing a predefined path or raster scan approach whereby the apparatus methodically traverses an inspection area or perimeter boundary.

In another embodiment, a combination or user-control and autonomous control may be employed.

The apparatus may comprise a communication means, which may permit the transfer of signals and/or data between the apparatus and a centralised control system, an operator, a cloud based server or the like. The communication means may comprise a wireless communication means, such as radio frequency, Bluetooth®, WiFi, satellite navigation system or the like.

The apparatus may be controlled remotely via the communication arrangement.

The apparatus may comprise an aerial and/or antenna, which may permit and/or improve remote communication between the apparatus and an operator and/or control system.

The apparatus may be configured such that a surveillance patrol route may be modified continuously or continually during use, i.e. on the fly, to respond to real time events and/or conditions.

The apparatus may employ artificial intelligence, and/or machine learning.

It should be understood that the features defined above or described below may be utilised, either alone or in combination with any other defined feature, in any other aspect or embodiment or to form a further aspect or embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 shows a perspective view of a ground-based drone apparatus, according to a first embodiment; Figure 2 shows a front view of the apparatus shown in Figure 1; Figure 3 shows a perspective view of the apparatus shown in Figure 1, with elliptical dome shaped members removed; Figure 4 shows another perspective view of the apparatus of Figure 1, with hub caps removed; Figure 5 shows a front view of the apparatus as shown in Figures 3 and 4; Figures 6 and 7 show an active pulley wheel assembly of the apparatus shown in Figure 1; Figures 8 and 9 show passive pulley wheel assemblies of the apparatus shown in Figure 1; Figure 10 shows an alternative example of the ground-based drone apparatus of Figure 1 with the elliptical dome shaped members removed; Figures 11 to 14 are schematic views showing the passive balancing arrangement of the apparatus shown in Figure 1; Figure 15 shows a perspective view of a ground-based drone apparatus, according to a second embodiment.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring first to Figures 1 and 2 of the accompanying drawings, there is shown a ground-based drone apparatus 1.

As shown in Figures 1 and 2, the apparatus 1 comprises two wheels 2, a support arrangement (generally denoted 3) and a drive arrangement (generally denoted 4). The drive arrangement 4 is disposed within the wheels 2 and is operable to engage the inner rim 5 of each wheel 2 to drive rotation of the wheels 2 and propel the apparatus 1 along the ground G. As shown most clearly in Figure 2, the support arrangement 3 is interposed between and configured to support the wheels 2 thereon, the support arrangement 3 configured to support the wheels 2 in a parallel or substantially parallel arrangement. The support arrangement 3 also supports a load to be carried by the apparatus 1, which in the illustrated apparatus 1 takes the form of a camera arrangement 6.

As will be described further below, the apparatus 1 is configured so as to have a centre of mass CoM offset from an axis of rotation A of the wheels 2, the centre of mass CoM providing a counterbalance to the load to be carried which acts to maintain the apparatus 1 in an upright orientation with respect to ground surface G. The apparatus 1 comprises a roll recovery arrangement (generally denoted 7).

In the illustrated apparatus 1, the roll recovery arrangement 7 comprises elliptical dome-shaped members 8 which are mounted on the wheels 2 and which extend outwards. The elliptical dome-shaped members 8 are configured to prevent the apparatus 1 from being displaced into a position that may otherwise be unrecoverable, for example with the wheels 2 substantially parallel to the ground G. The elliptical dome-shaped members 8 provide a further advantage of protecting the internal components, for example the drive arrangement, batteries, and drive wheels (not visible). Alternatively or additionally, the elliptical dome-shaped members 8 can also reduce or prevent in the ingress of water or debris, e.g. sand, dust, small rocks or the like.

Referring now also to Figures 3, 4 and 5 of the accompanying drawings, there is shown enlarged perspective views and a front view of the apparatus 1 shown in Figures 1 and 2. For ease of reference, the elliptical dome-shaped members 8 are not shown in Figures 3, 4 and 5 and part of the support arrangement 3 is not shown in Figure 3.

As shown, each of the wheels 2 comprises a tyre 9 disposed around rim 5, the rim 5 being profiled to receive the tyre 9. In the illustrated apparatus 1, the wheels 2 take the form of 26" (660.4mm) bicycle wheel, although it will be recognised that the wheels 2 may be of any suitable size and/or construction.

In the illustrated apparatus 1, the support arrangement 3 comprises a hub 10 and struts 11. The struts 11 are arranged in an x-shape, which provides a rigid structure, although the struts 11 may alternatively define any suitable configuration. The struts 11 are perpendicular or generally perpendicular to the wheels 2. The struts 11 are offset from the axis or rotation A of the wheels 2, being disposed above the axis or rotation A. The support arrangement 3 further comprises two chassis' 12, each chassis 12 coupled to distal ends of two of the struts 11. While in the illustrated apparatus 1, the hub 10, struts 11 and chassis' 12 are formed as separate components for ease of manufacture, it will be recognised that the hub 10, struts 11 and chassis' 12 may alternatively be formed as a single component or as sub-assemblies of two or more of the hub 10, struts 11 and chassis' 12.

The support arrangement 3 further comprises a pole 13, the pole 13 configured to be coupled to and/or support the load to be carried by the apparatus 1. Disposing the camera arrangement 6 on the top of the vertical pole 10 in this way positions the sensing unit 12 at an elevated position above the ground surface G, enhancing the field of view of the camera arrangement 6.

As shown in Figure 5, the pole 13 is perpendicular or generally perpendicular to the struts 11 (that is, the longitudinal axis of the pole 13 is perpendicular or generally perpendicular to the plane of the struts 11) and is also perpendicular or generally perpendicular to the axis of rotation A of the wheels 2 (that is, the longitudinal axis of the pole 13 is perpendicular or generally perpendicular to the plane of the wheels 2).

The pole 14 is coupled to the hub 10. In the illustrated apparatus 1, the pole 14 is of the same or similar construction to the struts 11. In the illustrated apparatus 1, the pole 14 is located centrally or generally centrally between the two wheels 2. While in the illustrated apparatus 1, the hub 10, struts 11, chassis' 12 and pole 13 are formed as separate components for ease of manufacture, it will be recognised that the hub 10, struts 11, chassis' 12 and pole 13 may alternatively be formed as a single component or as sub-assemblies of two or more of the hub 10, struts 11, chassis' 12 and pole 13.

As shown in Figures 3, 4 and 5, the pole 13 is coupled to, or forms, a camera mount 14 configured to support the camera arrangement 6.

As shown most clearly in Figure 5, in the illustrated apparatus 10 the support arrangement 3 further comprises a cross beam 15 disposed between the wheels 2. The cross beam 15 is perpendicular or generally perpendicular to the wheels 2 (that is, the longitudinal axis of the cross beam 15 is perpendicular or generally perpendicular to the plane of the wheels 2). The cross beam 15 is aligned or generally aligned with the axis of rotation A of the wheels 2 and so if offset from the struts 11. In the illustrated apparatus 1, the cross beam 15 is of the same or similar construction to the struts 11.

As described above, the drive arrangement 4 is disposed within the wheels 2, the drive arrangement 4 supported by the support arrangement 3.

In the illustrated apparatus 1, the drive arrangement 4 comprises two drive subassemblies 16, one drive subassembly 16 operatively associated with each wheel 2.

Referring now also to Figures 6, 7, 8 and 9 of the accompanying drawings, the drive arrangement 4 in the illustrated apparatus 1 takes the form of a pulley wheel drive system comprising an active pulley wheel assembly 17 and two passive pulley wheel assemblies 18, 19. The active pulley wheel assembly 17 comprises a motor 20 which is mounted within the chassis 12. In the illustrated apparatus 1, the motor 20 takes the form of a brushless DC electric motor. The active pulley wheel assembly 17 further comprises a first, drive, pulley 21 which engages and which is driven by the motor 20. The active pulley wheel assembly 17 further comprises a drive belt 22 which is disposed between the first, drive, pulley 21 and a v-grooved wheel 23. In use, the drive belt 22 transmits rotation of the motor 20 to the v-grooved wheel 23 which, in turn, drives rotation of the rim 5 of the wheel 2.

As shown in Figures 8 and 9, passive wheel assemblies 18, 19 each include a driven pulley 24, 25, respectively. The driven pulleys 24, 25 are rotatably mounted to chassis 12. The driven pulleys 24, 25 may be biased radially outwards by a biasing member such as a spring or the like, so as to maintain contact with the rim 5.

As described above, the apparatus 1 is configured so as to have a centre of mass CoM offset from an axis of rotation A of the wheels 2, the centre of mass CoM providing a counterbalance to the load to be carried which acts to maintain the apparatus 1 in an upright orientation with respect to ground surface G. In the illustrated apparatus 1, this is achieved by having an onboard power supply in the form of battery pack 26 (see Figure 3) disposed within the chassis 12 of each wheel 2, below the axis of rotation A of the wheels 2.

In the example shown in Figure 10, the apparatus 1 employs a direct drive arrangement in which the wheel 2 comprises a geared tooth arrangement 27 which engages directly with the drive subassembly 16 of the drive arrangement 4. In this example, the passive wheel assemblies 18, 19 are located at the top of the support arrangement 3 and are passively driven, i.e. free moving and caused to rotate as a planetary gear, i.e. by epicyclic gearing, by rotation of the drive arrangement 4. The inner rim of the wheel 2 comprises a generally V shaped profiled which is disposed between the tyre 9 and the geared tooth arrangement 27. The battery pack 26 is connected to the support arrangement 3. In this example, the roll recovery arrangement 7 and dome shaped members 8 have been omitted for clarity of the internal components of the apparatus 1. The camera arrangement 6 has also been omitted for clarity. In an example in which the camera arrangement 6 is implemented, the camera arrangement 6 may connect to the struts 11 in a similar manner as shown in Figures 1 to 5.

Referring now also to Figures 11 to 14 of the accompanying drawings, there is shown free body diagrams showing the apparatus 1 in various orientations, and demonstrating the passive balancing capabilities of the apparatus 1.

In Figure 11, the apparatus 1 is shown in a normal orientation in which both wheels 2 are generally level, and both are engaged with the ground surface G. In this orientation, the centre of mass CoM is disposed centrally between the two wheels 2 and the normal reaction forces R are equal and opposite to mass of the apparatus 1 exerted through the wheels 12. Consequently, the apparatus 1 is balanced and in a

stable orientation.

In Figures 12, 13 and 14, the apparatus 1 is tilted as an angle of 45 degrees and 90 degrees, and 135 degrees respectively. In each case, it can be seen that the moment forces exerted by the passive balancing arrangement relative to the reaction force R acts to self-right the apparatus 1.

It will be understood that various modifications may be made to the apparatus without departing from the scope of the invention as defined in the claims.

For example, Figure 15 shows an alternative ground-based drone apparatus 101. Apparatus 101 is identical to the apparatus 1, but with cross beam 15 removed.

The apparatus 101 provides greater clearance between than the hub 10 and the ground G, and permits the apparatus 101 to navigate over larger obstacles in use than the apparatus 1.

Claims

CLAIMS1. A ground-based drone apparatus, comprising: two wheels; a support arrangement interposed between and configured to support the wheels thereon; and a drive arrangement disposed within at least one of the wheels, the drive arrangement configured to engage an inner rim of the wheel to drive rotation of the wheel, wherein the apparatus has a centre of mass offset from an axis of rotation of the at least two wheels, the centre of mass providing a counterbalance acting to maintain the apparatus in an upright configuration, thereby providing a passive balancing arrangement of the apparatus.
2. The apparatus of claim 1, wherein the centre of mass of the apparatus is disposed below the axis of rotation of the wheels when the apparatus defines an upright configuration.
3. The apparatus of claim 1 or 2, wherein the apparatus is configured to carry a load above the axis of rotation of the wheels, the centre of mass of the apparatus counterbalancing the load.
4. The apparatus of claim 1, 2 or 3, comprising a roll recovery arrangement disposed on, attached to or forming part of the wheels.
5. The apparatus of claim 4, wherein the roll recovery arrangement takes the form of a passive roll recovery arrangement.
6. The apparatus of claim 4 or 5, wherein the roll recovery arrangement comprises one or more dome-shaped members.
7. The apparatus of any preceding claim, wherein at least one of the wheels comprises an inflatable tyre.
8. The apparatus of any preceding claim, wherein at least one of the wheels comprises a solid tyre and/or takes the form of a solid wheel.
9. The apparatus of any preceding claim, wherein the drive arrangement comprises a rotary drive, such as an electric motor.
10. The apparatus of any preceding claim, wherein the drive arrangement comprises one or more drive wheel configured to engage the wheel.
11. The apparatus of claim 10, wherein the drive wheel is configured to engage the internal rim of the wheel via a friction fit.
12. The apparatus of claim 10 or 11, wherein the drive wheel comprises a profile configured to engage the internal rim of the wheel.
13. The apparatus of any preceding claim, wherein the inner rim of the wheel comprises a profile.
14. The apparatus of claim 13 when dependent on claim 12, wherein the profile of the drive wheel is configured to engage with the profile of the inner rim of the wheel.
15. The apparatus of any preceding claim, wherein the drive wheel comprises a toothed and/or geared arrangement, which is configured to engage with a toothed and/or geared arrangement disposed on the inner rim of the wheel.
16. The apparatus of any one of claims 10 to 15, comprising a plurality of the drive wheels.
17. The apparatus of any preceding claim, wherein the drive arrangement directly drives the wheel.
18. The apparatus of any preceding claim, wherein the drive arrangement indirectly drives the wheel.
19. The apparatus of claim 18, comprising a transmission arrangement.
20. The apparatus of any preceding claim, wherein the drive arrangement is configured to drive the wheels at equal speeds, and/or driven and/or controlled independently.
21. The apparatus of any preceding claim, wherein the apparatus comprises a braking system.
22. The apparatus of any preceding claim, comprising an on-board power supply, such as a battery.
23. The apparatus of claim 22, wherein the power supply forms at least part of the passive balance arrangement.
24. The apparatus of any preceding claim, comprising a sensing and/or imaging device.
25. The apparatus of claim 24, wherein the sensing and/or imaging device comprises at least one of: a camera; a light source; a temperature sensor; a proximity sensor; a radar device; a sonar device; a LiDAR device.