GB2502250A - Unmanned vehicle variable surface pressure device - Google Patents

Abstract

The unmanned vehicle variable surface pressure device 1 includes a rotating four-blade, fixed pitch rotor 12 which is powered by a motor. The motor itself is fixed to a top plate 2 that has a side wall 8 and a flexible skirt 9. The device uses an electric motor or internal combustion engine or gas turbine to rotate the rotor 12. The rotor 12 has four fixed pitch tapered blades at ninety degrees to each other, each with a flat leading face 17 and trailing face 19. The device may house batteries to power the motor or a fuel tank for the internal combustion engine or gas turbine. Alternatively, the electric motor may be fitted to an external power supply. The device is fitted to unmanned vehicles and is used to increase the slopes and gradients that vertical take­off and landing unmanned aerial vehicles can land and take-off from, to enable unmanned wall climbing vehicles to operate on more slippery and inverted surfaces, to increase the stability and mobility of unmanned ground vehicles and permit surface crawling operation of unmanned underwater vehicles.

Description

Detailed Description

This invention relates to a device for varying the surface pressure of an unmanned vehicle.

More specifically, but not by way of limitation, the invention is directed to a uni-modal surface pressure device that creates variable surface pressure for the unmanned vehicle it is attached to by the creation of four low pressure vortices that create a pressure differential between the underside of the device, lower pressure region, and the higher ambient air or water pressure acting on the top of the device. The pressure differential results in a surface pressure increase for the unmanned vehicle that the device is attached to.

The variable surface pressure operation of this technology has been used to increase the surface pressure and traction of unmanned wall climbing vehicles on slippery, vertical and inverted surfaces.

In recent years there has been a steady increase in the usage of unmanned aerial vehicles, unmanned ground vehicles, unmanned wall climbing vehicles and unmanned underwater vehicles to perform reconnaissance and inspection missions globally in order to keep their human operators at a safe stand-off distance in harsh environments and war zones on land, at sea, underwater and in the air.

When an unmanned ground vehicle attempts to move over surfaces above a certain angle, the surface pressure and traction between its wheels or tracks and the surface will be insufficient for it to move over the surface and it will start slipping, this reduces its surface mobility and reduces its overall mission capabilities. Alternatively, an unmanned ground vehicle that attempts to lift a heavy load using an on-board manipulator arm will rely on its own weight and surface pressure to ensure it remains secure to the ground and prevent it from toppling over When an unmanned wall-climbing vehicle fitted with magnetic tracks or wheels attempts to climb a non-magnetic surface its magnetic tracks or wheels will not apply any surface pressure to enable it to climb the non-magnetic structure, so preventing it from performing its mission.

An unmanned wall climbing vehicle fitted with pneumatic suction cups that attempts to operate on a dirty or porous surface will not be able to perform its missions as it will suck up dirt, and porous surfaces will prevent an air tight seal so the unmanned wall climbing vehicle will slip as it cannot generate enough surface pressure to hold it against a surface.

An unmanned wall climbing vehicle that uses claws to grip onto surfaces that attempts to climb a smooth surface such as glass will not be able to perform its mission and will instead scratch and damage the surface it tries to climb.

An unmanned wall climbing vehicle that use a multi-bladed forced vortex device with blades mounted directly onto a disk that rotates rapidly, requires great amounts of energy to operate/rotate for a given amount of generated surface pressure.

An unmanned wall climbing vehicle that use a multi-bladed forced vortex device with blades dis-mounted from a disk that rotates rapidly, requires great amounts of energy to operate/rotate for a given amount of generated surface pressure.

An unmanned wall climbing vehicle that use a multi-modal forced vortex device with blades that have variable angle-of-attack and a variable aperture back-plate are mechanically complex, heavy and require great amounts of energy to operate for a given amount of generated surface pressure.

An unmanned wall climbing vehicle fitted with electro-adhesion devices that attempts to operate on wet surfaces will not be able to generate any surface pressure as the water on the surface its is climbing against will prevent a static charge from being imparted on the surface.

When an unmanned underwater vehicle attempts to inspect or carry out work on a moving object such as a ship or submarine underwater or attempts to carry out work on an underwater structure where the water current/flow is great, the unmanned underwater vehicle will have difficulty in maintaining its position so preventing it from performing work consistently.

Unmanned underwater vehicles have been fitted with magnetic tracks to enable them to inspect metallic ship hulls but they are unable to operate on non-magnetic ships or submarine hulls.

Unmanned underwater vehicles that use a multi-bladed forced vortex device with blades mounted directly onto a disk that rotates rapidly requires great amounts of energy to operate/rotate for a given amount of generated surface pressure.

Vertical take-off and landing (VTOL) unmanned aerial vehicles have great difficulty in landing or taking off from non-horizontal surfaces, such as roofs in urban environments or rolling flight-decks on ships operating in adverse weather conditions. The unmanned aerial vehicles lack the surface pressure to remain fixed and stable to non-horizontal surfaces. Unmanned aerial vehicles have been fitted with undercarriage tyres but their high centre of gravity means that they will topple over and crash if they attempt to land on non-horizontal, uneven surfaces or moving surfaces such as a rolling ship flight-deck.

Thus, it would be beneficial to provide a variable surface pressure device that consumes as little power as possible that could be fitted to unmanned aerial vehicles, unmanned ground vehicles, unmanned wall climbing vehicles and unmanned underwater vehicles so that their surface pressure could be varied to enable them to operate against non- horizontal surfaces, so enabling them to perform diverse missions in previously hard-to-reach locations.

To overcome these problems, the present invention proposes an unmanned vehicle variable surface pressure device with attachment means for attaching the unit to an unmanned wall climbing vehicle, an unmanned ground vehicle, an unmanned aerial vehicle or an unmanned underwater vehicle, that includes a rotating fixed pitch four-blade rotor, which is powered by a motor which is fixed to a top plate that has a side wall and a skirt attached to the side wall. The device uses an electric motor or internal combustion engine or gas turbine to rotate the rotor. The device may house batteries to power the motor or a fuel tank for the internal combustion engine or gas turbine, alternatively the electric motor may be fitted to an external power supply.

The variable surface pressure device may be retractable so that the device may be retracted into the side of an unmanned aerial vehicle, an unmanned ground vehicle, an unmanned wall-climbing vehicle or an unmanned underwater vehicle to reduce their footprint, aerodynamic drag and hydrodynamic drag, respectively when they are operating away from a surface.

The invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a variable surface pressure device fitted to a tracked unmanned wall climbing vehicle; Figure 2 shows the variable pressure device; Figure 3 shows the underside view of the variable surface pressure device; Figure 4 shows the air/fluid flow patterns of the variable pressure device in operation; Figure 5 shows the underside of the variable surface pressure device fitted with a mesh; Figure 6 shows the variable pressure device fitted to a tracked unmanned wall climbing vehicle climbing a vertical surface; Figure 7 shows the variable pressure device fitted to a tracked unmanned ground vehicle that is lifting an object with its on-board manipulator arm; Figure 8 shows the variable pressure device fitted to a tracked unmanned underwater vehicle that is perching against an underwater surface; Figure 9 shows two variable pressure devices fitted to a pair of tracked unmanned wall climbing vehicles that can be retracted into a vertical take-off and landing unmanned aerial vehicle that is perching on a non-horizontal sloped surface.

In figure 1, a variable surface pressure device 1 includes a top plate 2 which is attached to the chassis of an unmanned tracked vehicle 3 by mounting bolts 4, 5, 6, 7. A circular side wall 8 extends from the underside of the top plate 2 that jointly create a partially enclosed volume. A flexible skid 9 is attached to the side wall 8 and extends below the base of the side wall 8. A power-plant 10 attached to the centre of the top surface of the top plate 2 provides the energy to rotate the drive-shaft 11 which rotates the fixed pitch four-blade rotor 12.

Figure 2 shows a variable surface pressure device 1, detached from an unmanned tracked vehicle, includes a top plate 2 which has mounting holes 13, 14, 15, 16. A circular side wall 8 extends from the underside of the top plate 2 that jointly create a partially enclosed volume. A flexible skirt 9 is attached to the side wall 8 and extends below the base of the side wall 8. A power-plant 10 attached to the centre of the top surface of the top plate 2 provides the energy to rotate the drive-shaft llwhich rotates the fixed pitch four-blade rotor 12.

In Figure 3, the underside view of the variable surface pressure device 1 is shown, detached from an unmanned tracked vehicle, includes a top plate 2 which has mounting holes 13, 14, 15, 16. A circular side wall 8 extends from the underside of the top plate 2 that jointly create a partially enclosed volume. Aflexible skirt 9 is attached to the side wall 8 and extends below the base of the side wall 8. A power-plant 10 attached to the centre of the top surface of the top plate 2 provides the energy to rotate the drive-shaft 11 which rotates the fixed pitch four-blade rotor 12. The rotor 12 is a fixed pitch four-blade rotor whose four blades are equi-distantly spaced at ninety degrees to each other and have a flat leading face 17 that is offset and perpendicular to the central drive-shaft 11 and the rotor 12 has tour blades whose trailing taces 19 are flat and taper from the four blade tips 18 to the base of the following rotor flat tace 20. The rotor 12 is adapted to rotate within the partially enclosed volume created by the top plate 2 and the side wall 8 and the flexible skirt 9.Agap exists between the four blade tips 18 and the inside face of the flexible skirt 9.

Figure 4 shows the air/fluid tlow patterns of the variable pressure device 1 in operation.

Air molecules, that the variable surface pressure device 1 is surrounded by, moves in random directions when the four-bladed rotor 12 is stationary. When the power to the power-plant 10, that is connected via a drive-shaft 11 to the tour-bladed rotor 12, is increased, the rotational speed of the rotor 12 increases. In Figure 4, the rotation of the rotor 12 is anti-clockwise and the rotor 12 should be rotated in the correct direction with the shorter front leading edge 17 moving first in the direction of rotation, if the internal diameter of the skirt is less than 300mm. The fiat leading face 17 oteach of the four blades pushes air molecules in front of it and compresses the air, increasing the localized air pressure. Air molecules close to the blade tips 18 are accelerated and compressed through the gaps G1, G2, G3 and G4 between the rotating blade tips 18 and the skirt 9, which results in the air pressure to increase between the blade tips 18 and the skirt 9. A radial air velocity protile is created in which the velocity ot the air at the skirt 9 is zero and at the blade tip 18 the air velocity is a large fraction of the blade tip 18 speed. The air molecules close to the tapered back face 19 of each of the four blades ot the rotor 12 are dragged towards the tapered back faces 19 as the air pressure behind each of the four blades ot the rotor 12 is lower than the compressed air in tront of the leading edge 17 of each of the four blades. The air molecules that are accelerated in the gaps, Gi, G2, G3, G4 between the rotor tips 18 and the skirt 9 are therefore drawn towards the four rotor blade connection points 20 as the air pressure is lower there, this results in a rotation of the air behind each ot the four tapered back faces 19, resulting in the creation ot four vortices Vi, V2, V3, V4, between each of the blade trailing edges 19 and the following blade leading edge 17, as shown in Figure 4. The four vortices Vi, V2, V3, V4 move in real-time between the rotating four blades of the rotor 12 and the rotational vortex of air in the tour vortices Vi, V2, V3 and V4 results in the air pressure within each of the tour vortices Vi, V2, V3 and V4 to decrease, that causes the overall air pressure within the partially enclosed volume of air created by the circular side wall 8, skirt 9 and the top plate 2 to be reduced compared to the higher ambient air pressure acting on the top surface ot the top plate 2. The resulting pressure differential results in a directed force being generated that presses the device 1 and the unmanned tracked vehicle 3 it is attached to, to the surface that it is in closest proximity to, thereby producing the variable surface pressure against the surface that it is in closest proximity to.

By way of example only, one embodiment ot the variable surface pressure device 1 uses a top plate 2 that has a circular side wall 8 ot approximately 300mm internal diameter and 30mm deep and 10mm thick, a skirt 9 attached to the inside face ot the side wall 8 ot approximately 40mm depth and 2mm thick, a 15mm deep rotor 12 that consists of tour equi-distantly spaced blades each of which have a flat leading tace 17 that is offset and perpendicular to the central drive-shaft 11 and have a flat back face 19 that tapers from the blade tip 18 to the rotor blade connection point 20, the blade tip 18 and the skirt 9 are separated by approximately 50mm, and the gap between the rotor 12 and the top plate 2 is approximately 5mm, a 0.5kW electric motor power-plant 10 capable of rotating the rotor 12 at a maximum of 30,000 revolutions per minute (in air). Rotors with fewer than four equi-distantly spaced blades produced a smaller variable surface pressure in tests and rotors with more than four equi-distantly spaced blades produced a smaller variable surface pressure. Rotors with less than or more than four blades were less efficient and created a smaller variable surface pressure than the device 1 we are describing here.

The four blade rotor 12 described here and shown in Figure 1, Figure 2, Figure 3 and Figure 4 was found to be the most efficient rotor 12 design that created the greatest variable surface pressure for a given amount of power supplied to the power-plant 10.

The four blade rotor 12 shown in Figurel, Figure 2, Figure 3 and Figure 4 had the lowest but most efficient power consumption to surface pressure ratio of approximately 33Watts Newtons per square metre. In this embodiment, the top plate 2, side wall 8 and rotor 12 are constructed of a plastic composite and the skirt 9 is a neoprene rubber In this configuration the variable surface pressure device 1 has a mass of approximately 1kg, but can generate a variable surface pressure of approximately 15 Newtons per square metre. For a given rotor 12 diameter, the magnitude of the generated variable surface pressure is related to the rotational speed of the rotor 12 and the separation distance of the blade tips 18 to the skirt 9 and to the diameter of the rotor 12 and the size of the top plate 2 and the skirt 9 inner diameter and the depth of the rotor 12 itself and the stand-off distance between the top plate 2 and the rotor 12. If the gap Gi, G2, G3 and G4 distance is too small or too great then the rotor 12 will merely cut through the air and increased turbulence will be produced in the partially enclosed volume of air, created by the circular side wall 8 and the top plate 2, resulting in less powerful vortices Vi, V2, V3 and V4 being produced. Also, the direction of rotor 12 has a big effect on the surface pressure generated by the device 1. As an example, a small diameter device 1, say less than 300mm skirt 9 inner diameter, the rotor 12 should be rotated so that the leading edge 17 of the blades moves in the direction of rotation of the rotor 1 2,that is anti-clockwise on Figure 4. When a larger sized device 1, for example, more than 300mm skirt 9 inner diameter is used, the rotor 12 should be rotated so that the trailing edge 19 of the blades moves in the direction of rotation,that is clockwise on Figure 4.

If the gaps Gi, G2, G3 and G4, shown in Figure 4, between the blade tip 18 and the skirt 9 are too small, then insufficient air will be accelerated between the blade tip 18 and the skirt 9, which will result in the rotational speed and thus strength of the four vortices Vi, V2, V3 and V4 being reduced, so reducing the overall variable surface pressure that the device 1 exerts on a surface that it is in closest proximity to. If the gaps Gi, G2, G3 and G4 are too great, then turbulence from blade tip 18 eddies and the reduced air acceleration passing through the gaps Gi, G2, G3 and G4 will produce rotationally slower vortices Vi, V2, V3 and V4, which results in a lower overall variable surface pressure that the device 1 exerts on a surface that it is in closest proximity to. Maximum efficiency is achieved when the flow of air through the gaps Gi, G2, G3 and G4 is laminar, which is assisted when the side wall 8 and the skirt 9 have smooth surfaces.

The variable surface pressure created by the device 1 will enable an unmanned wall climbing vehicle, shown in Figure 1 and in Figure 6, to vary its surface pressure so enabling the unmanned wall climbing vehicle to climb vertical or inverted surfaces, that could be made from non-magnetic material or porous surfaces, without damaging the surface it is climbing on, as only the unmanned wall climbing vehicles tracks or wheels will be in contact with the surface. The varying surface pressure created by device 1 will also enable the unmanned wall climbing vehicle to carry payloads of varying mass or move over surfaces of varying surface roughness, from rough surfaces with bolts and cracks in them to very smooth, glass-like surfaces.

In Figure 5 a porous mesh may be attached to the underside of the device 1 to prevent the ingestion of foreign objects such as tiles into the rapidly rotating rotor 12. The mesh must be made from suitably strong material, such as metal or composites, but must present the minimal air resistance to the four vortices Vi, V2, V3 and V4 so that the mesh has minimal detrimental effect on the variable surface pressure that the device 1 generates. The mesh could be constructed from concentric rings of metal wire, 21 that could be welded together by inter-connector metal wires 22, the ends of which would be attached to the side wall 8 by bolts, 23, 24, 25 and 26.

In one embodiment, the top plate 2 and the side wall 8 may be constructed of metal that are welded together, clamped or bolted together. In another embodiment, the top plate 2 and side wall 8 may be constructed of a composite or plastic material that are glued together. In yet another embodiment, the top plate 2 may be constructed from a first material and the side wall 8 from a different material.

The medium in which the variable surface pressure device 1 operates will also influence the material used in its construction. If the device 1 is to operate in water, the rotor 12 rotational speed and the outer diameter of the rotor 12 required to produce a certain amount of surface pressure should be less than that used in air due to the higher viscosity of water compared to air. Consequently, the material used and the method of coupling different components together, such as the top plate 2 and the side wall 8, may be different dependent on whether the device is to be used in air or underwater.

Coupled to the side wall 8 and extending downward from it is the skirt 9 that extends the depth of the enclosed volume created by the top plate 2 and the side wall 8 and allows for deeper, lower pressure vortices Vi, V2, V3 and V4 to be generated, thereby creating a greater maximum surface pressure for the device 1. The skirt 9 also permits the device 1 to move over obstacles, when attached to unmanned vehicles such as that shown in Figure 1, such as bolt heads that may be present on the surface it is travelling over, without adversely affecting the pressure differential created by the four vortices Vi, V2, V3 and V4 created by the rapidly rotating four bladed rotor 12. The skirt 9 itself may be made from any suitable flexible but durable material such as rubber or plastic. The skirt 9 may also be attached to the side wall 8 using any suitable method such as rivets, glue or a circular clip. In order to minimize turbulence between the skirt 9 and the rapidly rotating rotor 12 the skirt 9 should be smooth and the interface between the skirt 9 and the side wall 8 should be as smooth as possible. Contact between the surface that the device 1 is in closest proximity to and the skirt 9, is not required for the device 1 to produce a variable surface pressure for the unmanned vehicle 3 that it is attached to, the device 1 is therefore airtight seal independent of the surface it is in closest proximity to, only the tracks or wheels of the unmanned vehicle 3 that the device 1 is attached to are in contact with the surface.

As illustrated in Figure 1, the power-plant 10 is attached to the top plate 2, using screws or adhesive, and a drive-shaft 11 passes through a hole in the centre of the top plate 2 into the partially enclosed volume created by the top plate 2, the side wall 8 and the skirt 9. The power-plant 10 rotates the drive-shaft 11 which in turn rotates the four-blade rotor 12 which results in the creation of the four vortices Vi, V2, V3 and V4 shown in Figure 4.

The power-plant 10 may be the power-plant that the device 1 is connected to, for example, or the main propulsor of an unmanned underwater vehicle 32 via an universal joint. Alternatively, the power-plant 10 may be a gas turbine, electric motor or an internal combustion engine, the electric motor may be connected to on-board batteries or may be connected to an external power source via an umbilical power line.

The side wall 8 is coupled at an approximately ninety degree angle relative to the top surface of the top plate 2. The partially enclosed volume comprises a substantially circular cross-section. At least one of the top plate 2 and the side wall 8 may comprise a plastic. At least one of the top plate 2 and the side wall 8 may comprise a metal. At least one of the top plate 2 and the side wall 8 may comprise a composite. The device 1 may be coupled to an unmanned ground vehicle 29. The device 1 may be coupled to an unmanned wall climbing vehicle 27. The device 1 may be coupled to an unmanned underwater vehicle 32. The device 1 may be coupled to an unmanned aerial vehicle 36.

Various changes in the materials and structure of the illustrated embodiments are possible without departing from the scope of the claims. The diameter of the rotor 12 can vary from millimetres to several metres and the depth of the rotor can vary from a fraction of a millimetre to several centimetres. The depth of the side wall 8 and skirt 9 can vary from millimetres to several centimetres. Numerous device l's may also be connected together in any number of configurations, separated by varying vertical and horizontal distances from one another.

Figure 6 shows the variable surface pressure device 1 fitted to a tracked unmanned wall climbing vehicle 27 climbing a vertical surface 28. The tracked unmanned wall climbing vehicle 27 could be fitted with wheels or tracks and two or more tracked unmanned wall climbing vehicles 27 could be interconnected to permit the tracked unmanned wall climbing vehicles 27 to traverse right angled corners or inverted surfaces such as ceilings of structures.

Figure 7 shows the variable surface pressure device 1 fitted to a tracked unmanned ground vehicle 29 that is lifting an object 30 with its on-board manipulator arm 31. The variable surface pressure created by the device I would increase the stability of a tracked unmanned ground vehicle 29 so enabling it to lift heavier objects without toppling over, so enhancing its overall mission effectiveness. The mobility of the tracked unmanned ground vehicle 29 would also be increased by fitting it with a variable surface pressure device 1 as the slope gradient it could operate on would be increased compared to relying on its tracks alone, which normally have only sufficient traction to take a tracked unmanned ground vehicle 29 up slopes of less than 50 degrees before slipping occurs.

Figure 8 shows the variable surface pressure device 1 fitted to a tracked unmanned underwater tracked vehicle 32 that is perching against a vertical underwater object 33, that could be a moving ship, submarine or a stationary dam or pipeline. The tracked unmanned underwater vehicle 32 fitted with a device 1 will be able to inspect or carry out work on an underwater object 33 even if the water current/flow is great, so increasing the mission capabilities of the tracked unmanned underwater vehicle 32.

Figure 9 shows two variable pressure devices 1 fitted to a pair of tracked unmanned wall climbing vehicles 34, 35 that can be retracted into a vertical take-off and landing unmanned aerial vehicle 36, that is perching on a non-horizontal sloped surface 37. The vertical take-off and landing unmanned aerial vehicle 36 fitted with one or more devices 1 will be able to land and take-off from non-horizontal sloped surfaces 37, including roofs and rolling ship flight-decks, so enhancing the mission capabilities of the vertical take-off and landing unmanned aerial vehicle 36.

Thus, while the invention has been disclosed with respect to a limited number of embodiments, numerous modifications and variations will be appreciated by those skilled a in the art. It is intended, therefore, that the following claims cover all such modifications and variations that may fall within the true spirit and scope of the invention.