Field of Iventition

Nhis specification relates to devices which can Interact with an abutting surface so that the device can retain adhesion with the surface, whether that surface be horizontal, angied to the horizontal or overhead. The devices may have their own motive power or be placed in a particular position.

Baekgroynd to the Invention

When an item of equipment or a vehicle is placed on a flat, level surface, it will remain in that place or be able to move if provided with its own motive power. Similarly, this also applies on a gently sloping surface. However as the angle of the slope increases, the coefficient of friction becomes critical and, over a certain angle, the item or vehicle will slide downwards as the acceleration due to gravity acting on the item or vehicle exceeds the frictional force resisting motion, At this, and greater angles, the item may be secured to the surface by an adhesive, by mechanical means or, if the surface was ferro-rnetaSlic, by magnetic means. While this is effective for Items which are intended to remain static, it is not usually viable for items which have to be moved, or are mobile under their own motive power and certainty not for oon-ferro-magnef!c surfaces.

Suction cups can be used on smooth, flat surfaces, such as glass, and experienced climbers can scale vertical walls of ice using a pair of ice axes and boots with toe spikes but these principles do no! have general industrial application and may damage the: surface of the wall or ceiling,

There are many instances where access is required, say, to wails, ceilings, etc, where detailed Inspection of the surfaces, monitoring the environment or to undertake a piece of work, is required and access is not readily available, e,g. because the wail / ceiling is part of a confined space where noxious gases might be present Also, when relatively simple tasks have to be performed in relatively inaccessible Ideations, It would often be much easier and cheaper to be ab!e to use a simple robotic device than to have to erect scaffolding or get in a cherry picker. Other Instances of difficult access are the underwater Inspection of ships' huiis, offshore oil / gas rigs and related equipment, e.g. inside tanks, etc.

Modern robotic: techniques are now so advanced that unmanned groand, hill climbing and aerial vehicles are practical realities and some of the applications that modern robotic devices can undertake, either on these vehicles or in space, would have been unthinkable Only a few years ago:. Vertical waii-cilmbing vehicles woiiid add ^: 1p these capabilities,

Rebdlic means able to adhere to, or to move over, steep slopes, vertical walls or inverted surfaces are known EP 0 787 646 A2, EP 1 87© 613 A and G8 2 295 799 A) but all employ partial vacuum means whereby air is drawn from near the adjacent surface or extracted from a chamber, the open side of which is adjacent to the surface. To create a partial vacuum, particyiarly a high vacuum, requires a great deal of energy as a high speed fan is necessary to generate and maintain the pressure difference across the fan blades. This level of power can be provided via an umbilical cable for an extended period of time but to supply it: Willi a battery greatly limits the robot's operational time. Furthermore, whirring blades are noisy, which limits theiapplicability of such means, e.g. for covert, surveillance activities. The use of a vehicle: which can attract: Itself to & surface will Increase the tractive effort available: to move the vehicle or help it remain in a given place.: in recent years there: has been a steady increase in l!ia usage Of unmanned aerial vehicles, unmanned ground vehicles, unmanned wall climbing vehicles and unmanned underwater vehicles to perform inspection and / or maintenance missions in order to keep their human operators at a safe distance from harsh or dangerous environments. Means to attract, and hold, the vehicle against the surface would be highly beneficial, e.g. to hold, say; an aerial vehicle firmly onto the deck of a heaving ship. Similarly, such means would allow an aerial vehicle to land on a roof and rest until needed again.

Thus, there is an urgent need for devices able to adhere to or to climb steep slopes and vertical surfaces and be able to undertake Industrial operations, with minimal power requirements, in these inaccessible locations, Ideally, the devices wlli also be operable on inverted surfaces, e.g. ceilings.

Summary of -the invention

The present invention is defined ih the attached independent claims, to which reference should now be made. Further preferred features may be found in the sub-cialms appended thereto,.

A first aspect of the inventson relates to a vortex generator comprising;- a cylindrical housing with a closed first end face and an open second end face;

an impeller with a plurality of blades rotatably mounted within the cylindrical housing;

drive means for driving the impeller about a central axis of the cylindrical bousing; whereby, in use, the rotating impeller generates a vortex with a low pressure core between each pair of adjacent blades so as to form a vortical attraction force thai attracts the vortex generator towards a horizontal, sloping:, vertical and/or inverted surface arranged adjacent to the open second end face,

A leading edge of each blade may lie along a radius of the impeller axis. A trailing edge of each blade may lie along a chord of the circle swept fey the blades. The leading and trailing faces of each blade may be fiat surfaces lying in a plane normal to the plane of rotation of file impeller,

Preferably, the tip of each blade is arranged a predetermined clearance distance from the cylindrical housing:. The tip of each blade may he arranged a predetermined clearance distance from the cylindrical housing so that in use, the rotating impeller further generates a liypdcycioida! fluid flow with mini-vortices, The predetermined clearance distance may fee selected from the range of 0,05 _^ 0.150, where 0 is the internal diameter of the cylindrical housing.

The vortical attraction force may maintain the vortex generator a! a predetermined clearance distance from the adjacent surface.

In an embodiment the vortex generator may be an apparatus for generating a vortex having a reduced pressure at its core comprising

a chassis er a means to secure the apparatus to a supporting structure;

a source of power;

a driving motor;

a cylindrical housing having a falt closed first end face and an open second end face;

an irhpejisr rotatabie on the axis of the cylindrical housing with a drive shaft passing through said fiat Pldsfed first end face via a seal so that a fluid may not pass from one side of the flat closed first face to the other,

characterised In that the cylindrical housing Is mounted on the chassis/supporting structure so that Its open second end face is essentially parallel and close to, but not touching, an essentially planar surface and that when the ©Vive motor is activated, the impeller is caused to rotate generating a vortex within the cylindrical housing so that a force is generated attracting the vortex generator towards : the surface,

In this embodiment the impeller has a plurality of blades. A vortex may he created In the space ©@¾«een each pair of adjacent blades of the impeller. in this embodiment, the leading edge of each of the blades may lie along a radius of theim peter axis. The trailing edge of each of the ©fades may lie along a chord of the circle swept by the blades. The leading arid trailing faces of each of the blades may be flat surfaces lying in a plane normal to the plane of rotation of the impeller. The clearance between the; tips of the blades and the cylindrical bousing may lie between 0.05-0.15D, where 0 Is the internal diameter of the: cylindrical housing,

A second aspect of the invention: relates to a vehicle for accessing a horizontal, sloping, vertical: and/or inverted surface: comprising;

a supporting structure;

a vortex generator according to the first aspect of the invention for attracting the vehicle to the surface;

means of motive power for moving trie vehicle across the surface,

The means for motive power preferably provides sufficient motive power to move the vehicle oyer the surface, whilst the vehicle is attracted to the surface by the vortex generator; The means of motive power may include wheels, tracjied members and/or steerabie means.

The vehicle may comprise an electrical, hydrocarbon or pneumatic source of power for powering the means of motive power and/or the driving motor of the vortex generator,

The supporting structure may be constructed from one or more strong, light materials. The material may include metallic alloys, glass and/or carbon fibre reinforced plastics.

The vehicle may further comprise means for undertaking an operation when the vehicle is located on the surface. The means for undertaking an operation may include apparatus for monitoring the surface and/or the environment at the position, means for performing work, means for maintaining, installing or replacing an stem. The means for monitoring the environment may include apparatus for generating visual images of the surface and/or environment and sending the visual images for viewing at a remote ideation and/or means for detecting gas and/or radiation. The means for undertaking an operation may ineiode drilling means. The means for undertaking an operation may comprise anti-vibration means for timiting the transfer of drilling vibration from the drilling means to other components of the -vehicle. The means lor undertaking an operation, .may comprise -a debris collector. The means for undertaking an operation may include a handling means such as an articulated arm. The vehicle may comprise control means for controlling the operation of the vehicle in response to receiving remote instructions. The control means may control the operation of the means for motive power, the vortex generator and/or the means for undertaking an Operation In response to receiving remote instructions. in an embodiment, the vehicle may be an apparatus for accessing horizontal, sloping, veriicai and/or Inverted surfaces and capable of undertaking operations when positioned at the surface, comprislng:- a supporting structure having a means of motive power;

a source of power;

a driving motor; and

a vortex generator comprising

a eyiindhca! housing having a flat closed first end face and an open second end face, and

an impeller fotatabie on the axis of the cylindrical housing with a drive shaft passing through said flat closed first end face via a seal so thai a fluid may not pass from one side of the flat closed face to the other;

characterised in that

the cylindrical housing Is mounted on the supporting struciure so that its open second end face is essentially parallel and close to, but not touching, an essentially planar horizontal, sloping, vertical and/or Inverted surface;

when the drive motor is activated^ the Impeller is caused to rotate generating a vortex, having a reduced pressure at its core, within the cylindrical housing so that a force is generated attracting the vortex generator towards the surface, and

when the means for motive power is activated, the apparatus is able to move over the horizontal, sloping, vertical or inverted surface on which the apparatus; is: located anrj is capable of undertaking operatioiis;

In this embodiment, the means of providing motive power may include wheels, includes tracked members andfer includes steerable means, The sieerabfe means may allow the apparatus to be turned through angles. in this embodiment, the source of power may be either electrical, hydrocarbon or pneumatic. The electrical power may be supplied by an .on-board battery or supplied by a power cable from an external source. in this embodiment, the motive power may be sufficient to move the apparatus of the invention over the surface, despite the vortical attraction ^' force towards that surface. in this embodiment the supporting structure and other components of the apparatus may be constructed of strong, light materials. The strong, light materials may include metallic alloys, glass and/or carbon fibre reinforced plastics, in this embodiment, the apparatus may comprise means to ^' undertake operations from a position on the sloping _t vertical or inverted surface may include apparatus for monitoring of the environment, The apparatus for monitoring of the environment may include apparatus for generating and sending visual images for viewing at a remote location and/br apparatus to detect particular gases or radiations.

In this embodiment, the means to undertake operations from a position on the horizontal, sloping, vertical or inverted surface may include apparatus for the maintenance of items, and/ or replacement of items, in the environment, tools required for the work, visual means to be able to use those tools and means to control the use of the tools. The means to undertake operations from a position on the horizontal, sloping, vertical or inverted surface may include apparatus for performing work in the environment. The means to undertake operations from a position on the horizontal, sloping, vertical of inverted surface may include apparatus for installing items of equipment in the environment, in this embodiment, the apparatus may comprise an articulated arm provided with gripping means at the distal end for holding and using tools. The apparatus may comprise a location for holding topis and/or equipment for use by the articulated arm, The tools and equipment for use by the articulated arm may Include a powered drill a drill bit and the means to use them. The apparatus may comprise means for moving the power cable to stop. it getting entangled with the articuSated arm. in this embodiment, the apparatus may comprise a eahiera or viewing means for generating and transmitting images for viewing at a remote location. In this embodiment, the apparatus comprises means for receiving instructions sent from a remote location to components of the apparatus to cause them to drive and/or steer the apparatus and/or to undertake monitoring of the environment and/or maintenance or replacement of items in the environment and/or to perform work in the environment and/or to use such tools or other equipment available to the apparatus as may be required to complete any or ail of the above tasks or accomplish any other tasks within the capabilities of the apparatus, in this embodiment, the apparatus may comprise coupling means for coupling the apparatus to another apparatus nominally at right angles so that the combined apparatus" can move from a floor to a wall and/or from a wall to a ceiling and/or vice versa.

In this embodiment, the coupling means comprises a rotational element so that the combined apparatus' can access two planar surfaces which are not mutuaily aligned at right angles to each other. in this embodiment, the apparatus comprises coupling means for coupling the apparatus to one or more further apparatus end-to end, side-by-side or end-to-end and side-by-side to provide a larger operating platform, more securely attracted to the surface.

In this embodiment, the coupling means comprises means to lift one of the apparatus over, or around, a discontinuity In/on the surface being traversed or past a discontinuity between otherwise planar surfaces, In this embodiment, the area of the supporting structure may be increased sd that a plurality of vortex generators is mountable therein.

In this embodiment, the apparatus may be operated In conjunction with, or as part of, other robotic systems to forms composite units for specific operations.

A third aspect of the invention relates to a system for accessing horizontal, sloping, vertical and/or inverted surface: comprising a first vehicle according to a first aspect of the invention, a second vehicle according to the first aspect of the invention and coupling means for coupling the first vehicle, the second vehicle and/or a device together.

The coupling means may allow for the relative movement between the first vehicle, second vehicle and/or the device. For example, the coupling means may be rotational coupling means that allow lor relative rotation of the first vehicle, the second vehicle and/or the device. The .coupling means may be telescopic coupling means that allow for rotative extension and retraction cf the first vehicle reiative, second vehicle and/or the device. The coupling means may be elevating coupling means that allow for relative raising and lowering of the first vehicle relative, second vehicle end/or the device,

A foyrih aspect of the invention relates to a method of generatirtg an attractive force towards a surface comprising the steps of:

providing a vortex generator according to: the first aspect of the invention;

arranging the open second end face of the vortex generator adjacent the surface;

rotating the impeller of the vortex generator so as to generate a vortex with a reduced pressure core between each otade of the impellers such that a pressure differential is formed between amoient pressure and the reduced pressure cores of vortices which has the effect of generating a vortical attraction force attracting the vortex generator towards tie surface.

A fifth aspect of the invention relates to a method for accessing a horizontal, sloping, vertical and/dr inverted surface comprising the steps of;

providing a vehicle with a supporting structure,, s means of motive power and a vortex generator according to the first aspect of the invention ;

arranging the open second end face of the vortex generator adjacent the surface;

depending on the traction required, activating the vortex generator to attract the vehicle towards the surface;

activating the means for motive power to move the vehicle across the surface,

The method may further comprise the steps of:

providing the vehicle with means for undertaking an operation when located on the surface; and activating the said means.

The method may further comprise the steps of :

providing control means for controlling the operation of the vehicle in response to receiving remote Instructions; and

operating the vehicle in response to the receiving remote instructions.

In an embodiment, the method is a method for accessing horizontal _. , sloping, vertical and/or inverted surfaces and having the capability of undertaking operations when at the surface, comprising the steps oft- providing an apparatus comprising:;

s supporting structure, having a means of motive power;

a sours© of power ^' ;

a driving motor;

a vortex generator haying

a cylindrical housing having a fiat closed first end face and an open second end face;

an impelier rotataole on the axis of the cylindrical housing with a drive shaft passing through said flat closed first end face via a seat so that a fluid may not pass from one side of the flat closed face to the other;

means of accessing the horizontal, sloping, vertical and/or inverted surfaces; and means of undertakiiig operations at the surface;

mounting the apparatus so that the open second end face is essentially parallel and close lo, but not touching, an essentially planar horizontal, sloping, vertical and/or inverted surface;

activating the drive motor to rotate the impeller so as to create a vortex, having a reduced pressure at its core, within the cylindrical housing so that a force is generated attracting the apparatus towards the horizontal, sloping, vertical or inverted surface on which the apparatus is located;

using the means of accessing to reach a particular location on the horizontal, sloping, vertical and/or inverted surface;

using means to undertake operations at the said location.

In this embodiment, the method may Include the step of climbing/descending surfaces to predetermined positions from where predetermined operations can be carried out and/or have been carried out.

In this embodiment, the method may include the step of using the means of accessing to steer the apparatus to the location at the surface. in this embodiment, the method may include the step of using the means to undertake operations to generate images of the location and items at the location and to transmit the images to a remote location from where operational instructions are sent to the apparatus.

In this embodiment, wherein the means to undertake operations may include articulated means and the method may include the step of using the articulated means at the said location to undertake the required operations. In the embodiment, the method may Include the step of coupling two apparatus together nominally at right angles to each other so that the combined apparatus' can be used to enter a chamber, move along the floor to a wall, transfer to and climb the wail and, if required, turn through 180° and climb to and transfer to the ceiling and move along the ceiling to its predetermined operational point, undertake an operation at that point and, when the operation is complete, return by the same, similar or a different routs to its starting point or to another required destination.

In this embodiment, the method may Include the step of providing a plurality of vortex generators, either end-to-end, side-by-slde or both end-tOsSnd and side-by-side on the supporting structure.

In this embodiment, the method may include the steps of providing means to move a power cable and using the means to stop the power cable from getting entangled with any articulated arm(s} or other components on the apparatus or combined apparatus turning/ turme through 1 ^' 80* or otherwise manoeuvred.

In this embodiraeot, the method may include the steps of providing means to move the power cable arid the: articulated arm and using the means to move the power cable and the articulated arm so as to avoid entangling the power cable or to disentangle the power cable should it have become entangled during the turning of the combined apparatus through 180'· or during other manoeuvres.

In this embodiment, the method may include the steps of providing a connection between two apparatus and using the connection to lift one of the apparatus over, or around, a discontinuity in/on the surface being traversed or past a discontinuity between otherwise planar surfaces.

In a preferred embodiment of the invention, the vortex chamber is a right cylinder, with the diameter many times greater than the depth, Qne face is closed by a flat plate, which extends beyond the limits .of the : cylinder to provide means to mount the vortex generator in other apparatus, The other face is open, A motor, mounted on the plate but outside the cylinder, drives an impeller mounted axially in the cylinder. The impeller has flat leading and iraliing edges so that its rotation does not generate any pumping action but merely spins the fluid around in the cylinder. This action generates a vortex between each pair of adjacent blades. Vortices, like natural tornados, have an annyius of rapidly spinning air and a core of reduced pressure. The effect of the plurality of low pressure cores is to draw a flat surface towards the open face of the vortex generator, or conversely, to hoid the vortex generator against a fiat surface, whether that surface is horizontal, angled to the horizontal, vertical or inverted, Vortices ear! be generated in any fluid, i.e. gas or liquid, In the present invention, a vortex generator may be mounted to a mobile vehicle, preferably a tracked vehicle, in use, the vortex generator is aligned parallel to and adjacent to _s but hot in contact with, the surface on which the vehicle is located and that surface may be horizontal, angled to the horizontal, vertical or inverted. As the vortex generator is close to, hut not in contact with, the surface, the vehicle can move over the syrface _t a-8, climb a wall, to undertake an operation high on the wall, out of reach of normal access. The vehicle is adaptable to a wide range of applications, including transferring from a vertlca! wail to a celling. Flower for the motor may be from an on-board source or provided externaSSy via an urnbil leal cable or tube, Brief PescrisstSon of the Drawings

For a clearer understanding of the invention and to show how it may be carried into effect, reference will now be made, by way of example only, to the accompanying /drawings in which:-

Figure 1 is a perspective view of an embodiment of a vortex generator according to the presenl: invention;

Figure 2 is a plan view of the open face of the vortex generator shown in Figure 1 ;

Figure 3 is a plan view of the open face, of the vortex generator shown in Figure 1 indicating an air flow pattern within the vortex generator;

Figure 4 is a perspective view of an embodiment of a Vehicle according to the present invention thai has been fitted with the vortex generator shown in Figure 1 ;

Figure 5 is a plan view of the open face of the vortex generator shown in Figures 1 to 3 fitted with a protective mesh;

Figure ø is a side elevation of the vehicle shown in Figure 4 climbing a vertical surface; Figure 7 is a side elevation of the vehicle shown in Figure 4 carrying a load via an articulated arm;

Figure 8 is a side elevation of the vehicle shown in Figure 4 parching agalbst an underwater surface and connected to an underwater Remotely Operated Vehicle (RC3V); Figure 0 is a side elevation of two vehicles shown in Figure 4 deployed from a vertical takeoff and landing aerial vehicle perching on a sloping surface;

Figure 10 is a side elevation of vehicles shown in Figure 4 connected together and moving along a floor and up a wail and along a ceiling and down a wail; Figure 11 is a side elevation of the vehicle shown in Figure 4 perching against a vertical surface and drilling a hole therein;

Figure 12 is a side elevation of the vehicle shown in Figure 4 perching against a vertical wall and provided with a multifunctional handing and gripping means; and

Figure 13 is a side elevation of two vehicles shown in Figure 4 perching against a vertical surface and connected together by multifunctional member thal is able to lift one of the vehicles off the surface, relative to the other vehicle, and manoeuvre it as required so that the combined vehicles may move over, around or past an obstacle, Detailed Description of the invention

In the following description the same reference Humeral is used for identical components in different Figures or for different components fulfilling an identical function.

Referring to Figures 1, 2 and 3. a vertex generator 1 consists of impelier 2, provided with multiple blades 3, driven by motor 4, mounted on plate 7, and rotating within a generally right cylindrical housing 5, As shown in Figure 1, the upper face of vortex generator 1 is flat, fast with housing 5, closed and formed by part of plate 7, which is extended, as shown, and provided with holes 8 to allow it to be secured to other components. The lower face of vortex generator 1 depicted in Figure 1 is open and housing 5 may be extended downwards by means of a flexible skirt 6, or simply by extending housing § away from plate 7 beyond the plane swept by Impeller 2. The housing, closed upper face, open lower face and optional skirt define a vortex chamber 17. To minimise air resistance, housing should have as smooth a surface as possible, e.g. be made of an engineehng grade piastic. Figure 2 shows a plan view of impeller 2 in its housing 5 looking inwards through the open, lower face of housing. The impeller comprises a plurality of blades 3. The blades are preferably equally spaced, A four b!aded impeller 2 dividing the housing into quadrants is shown for illustrative purposes only. Drive shaft 2A passes through plate 7 via a seal (not shown) so thai fluid {eg. air, gas, water) cannot pass through from the inside of vortex chamber 17. The impeller s is designed to spin fluid in a plane that is parallel to the plane of rotation and around an axis that is parallel to axis of the housing. The impeller does not act as a pump moving fluid from one of its sides to the other. Each blade of the impeller extends radially from the drive shaft 2A towards the housing. Each blade consists of a leading edge (side) 9, which is a fiat face with Its plane normal to the plane of rotation 11 of impeller 2, Trailing edge 10 is another planar face normal to the plane of rotation 11 of impeller 2, or it may be faired symmetrically about the mid-fine of the piane of rotation of impeller 2, so that it does not generate any pumping action, As shown, the blades 3 taper and have rounded or flat lips 12> There Is a clearance 13 between tips 12 and housing §, There is a clearance between the .blades: 3 and the plate 7, Impeller 2 rotates 11 in cylindrical housing 5. As impeller 2 turns 11 , the fluid in each of the guadrants, between two adjacent blades will be subject to;-- i) a positive (increased) pressure from the leading edge 9;

it) a negative (reduced} pressure from the trailing edge 10; and

ili) drag near the eireumferenea of the cylindrical housing from contact with the boundary layer 15 adjacent to housing 5,

The combination of these forces generates a spinning vortex 14 in each quadrant as sliovvn in Figure 3, A reduced pressure Is generated in the central, core or axial zone of each vortex. As shown, there are as many vortices 14 as blades- on the Impeller so that an essentially balanced reduced pressure Is generated over the whole area of the vortex generator 1, Adjacent to the housing 5 may be a very thin boundary layer of fluid 15; this may be only a few molecules thick and may exhibit laminar ¹ flow but it wit! have a drag effect on the highly-turbulent mass of rotating fluid in vortex chamber 17, As the impeller 2 turns 11 , the vortices 14 orbit axis 2A end may continuously exchange fluid with the annular, circumferential zone, I.e. between boundary layer I S and vortices 14.

As shown in Figure 3, the fluid in the annular sone near the housing S may be dragged round by Impeller 2 and may be rotated locally 16 by the interaction with a vortex 14, giving a hypopydaid-iype of flow pattern 16, As shown, the hypocycioldal flow may create a number of mini-vortices I SA, which advantageously provide a secondary vortical effect In addition to the primary vortical effect generated by the vortices 14 between the adjacent blades.

Thus, as impeller 2 turns 11. the plurality of vortices 14 between the adjacent blades, and optional additional mlni-vortlces 18A, form a fixed vortical pattern In a form of 'standing wave'. The vortices 14 (and optional vortices 16A) generate zones of a substantial negative pressure in chamber 17, The pressure difference (ΔΡ) between ambient fluid pressure acting on the top of surface 7 and over the exterior of the vortex chamber 17 and the reduced pressure generated by the vortices 14 (and optional mini-vortices 16A) inside vortex chamber 17 forms a force that has the effect of attracting (pushing) the vortex generator 1 towards any surface placed adjacent to the open face of chamber 17, Since the impeller is only required to spin fluid within the vortex chamber 17 less power is required to maintain the vortices anel achieve a vortical attraction force than is required hy prior art devices to pump fluid from one region to another. Hence, the vortex generator provides a superior attracting effect for a given amount of energy than prior art devices that generate a pressure .differential by pumping fluid. Accordingly, the vortex generator requires lower fnergy sources and can be operated for a longer period of time than prior art devices using vacuum pumps. For example, the vortex generator may operate for up to three hours with current battery technology, it has been found that the clearance 13 between the blade tips and housing 5 influences 8i®: formation, of the vortices _: and so is a key factor in We efficiency of the vortex generator. If the clearance is too small then the force attracting the vortex generator 1 to a surface 23 is restricted, If the clearance is too large, the force attracting the vortex generator to a surface is aiso compromised. Hence, the blade tips are preferably arranged a predetermined clearance distance from the housing so as to enhance the vortical attraction force. The clearance distance may be. regulated so as to optimise the low pressure cores of the vortices 14 formed between the adjacent blades. The clearance distance may be regulated so that the mini-vortices 18A are generated, thereby improving the net vortical attraction force of the vortex generator Tne predetermined clearance 13 is preferably selected from the range 0.05-0.150, where D is the interna! diameter of housing §\

The clearance between the blades and the plate 7 is preferably regulated so as to minimise turbulence. The clearance between the blades and the plate 7 is preferably selected from the range 0.01 -Q.Q4D, where P is the Internal diameter of housing 5.

When attracted to the adjacent surface, the vortex generator may form a mating contact with the surface. Alternatively, if the vortices 14 {and optional vortices 16a) generated by the rotating irnpelier extend beyond the vortex chamber 17 towards the adjacent surface then the vortical attraction force may be sufficient: to attract (arrange and maintain) the vortex generator In spaced relation from the adjacent surface. This gap space forms a clearance 25 (see Figure 6} between the attracted vortex generator and the adjacent surface. Depending on the vortical attraction force, the attracted vortex generator may be maintained a clearance distance of up to approximately 20mm from the adjacent surface, The spinning fluid flow of the vortices hinders fluid from flowing through the gap space between the adjacent surface and vortex generator.. Hence, contrary to prior art devices that pump fluid, the vortex generator does not require a seal between cylindrical housing and the adjacent surface to achieve an attracting effect and It is not disrupted by the clearance distance.

Figure 4 shows a vortex generator 1 incorporated into a tracked vehicle 18. Cross members 19 are bolted fast 20, via holes 8, with plate 7 to make a chassis to which wheels 22 and; tracks 21 are attached, Normally, each track 21 would have one driven wheel 22 and one idler 22 bu t two driven wheels 22 may be used if greater tractive effort is required. Vehicle 18 would have an appropriate power supply (e.g. an on-board battery or remotely via an umbilical 37 (see Figure 10)) and control systems, which are not shown to avoid confusing detail.

The vehicle I S can traverse a porous surface, which the prior art vehicles: might not be able to manage, if surface 23 has loose material on it, e,g. flaking palht, a protective: rhesb 24, as shown In Figure 5, may be provided to prevent ingestion into chamber 17.

Figure 6 shows vehicle 18 climbing a vertical . wail 23. M shown the dimensions of tracks 21 and wheels 22 and their location relative to chassis 7 gives a clearance 25 between housing S and surface 23. The clearance 25 advantageously allows vehicle I S to pass over irregularities on surface 23, e.g. boil or rivet heads, etc., without losing adhesion to the surface. When the vortex generator is activated, vortices 14 (and possib!y 16A too) extend beyond the volumetric cylindrical disc 17 swept by blades 3, away from plate 7 down to surface 23 and exert . the low pressure, suctionai attraction, which holds vehicle 18 against wall 23, As the partial vacuum in vortices 14 is maintained by a rapidly rotating tube of air, it is not disrupted by the clearance distance 25.

Vehicle 18 and vortex generator 1 may be powered by ^M on-board" means, e.g. a battery or an internal combustion engine or by external means, e.g. via an umbilical connection using electrical or pneumatic power. Clearly for wall climbing activities and the need to be able to undertake operations on the Wail, overall weight will be a key factor. Thus, the weight of vehicle 18 must be minimised, dictating the use of strong. Sight materials of construction, such as high strength alloys, engineering plastics and glass or carbon fibre composites.

In a preferred embodiment of the vehicle where the cylindrical housing of the vortex generator has an interna! diameter D the dimensions of>

I) impeller diameter may range from 0.85 to 0.8SD,

ii) blade tip clearance may range from 0.15 to Q.05D,

tit} blade face depth may range from 0,06 to 0,100, lv) clearance between blades 3 and plate 7 may range from 0.01 -0,04D, and

V) clearance distance 2S between housing 5 and surface 23 may range from 0,03- 0<Q9D< In the preferred embodiment, the design of impeller 2 has the leading edges 9 of blades 3 lying along radii of impeller 2 and the trailing edges 10 lying along chords of the circle swept by blades 3, impellers 2 with three, four or five blades performed best. In the Figures, anticlockwise rotation 1 1 of impeller 2 is shown; the direction of rotation Is not critical and clockwise rotation is equally viable provided impeller 2 is fitted with the leading and trailing edges and clearances, as taught Rotational speeds of up to 40k r.p.m. in air have been used and vertical suctions of up to βΟ ^' ΟΟΝ/m ² have been generated. For use in water, slower rotational speeds would be used and the other dimensions may have to be adjusted aocordi hgiy.

Figure 7 shows a vehicle 18 according to the present invention carrying a heavy load 2? via articulated arm 28. The vortex generator with housing § provides an additional downward force (not shown) preventing vehicle 18 from overturning about point A.

Figure 8 shows an underwater vehicle 18 perching against the vertical side of a ship's hull or oil rig leg 28, Here, the vortices (not shown) are created in water. Item 30 represents an unmanned, underwater Remotely Operated Vehicle, commonly termed a RGV, and vehicle 18 Is 'parking' the ROV between operations, in this case, both vehicle 18 and ROV 30 could be powered by the same umbilical power cable (not shown). Figure. 9 shows an Unmanned Aerial Vehicle (UAV}; 31 , _: perching on a roof 33 and coupled between two vehicles 18 according to the invention. As with Figure. 8, this is a 'parking' application. UAV 31 would hover over roof 33, deploy vehicles 18 using deploy means 32, start the vortex generators of the vehicles and gradually lower itself until vehicles 18 contacted roof 33 and established a grip thereon. Then UAV 31 would stop its engine and wait, When UAV 31 was instructed to; go into; action again, It would start its engine: and, when it was running normally, stop the vprte* generators and take off after retracting vehicles 18 into its fuselage. The principle of this application may be applied to landing on the heaving decks of ships in rough seas.

Figure 10 shows how two vehicles ISA, 18B connected together 35 using rotational coupling means 30 can be used io gain access to multiple surfaces at different angles, For example, the two vehicles 18 A, Ί8Β can gain access from a floor 34A to a wall 348 or from a beillhg 34C to a wail 348. In this case, the rotational coupling means 36 is provided to allow for movement between the vehicles over corner angles. When moving from the floor 34A to. the wall 34B, the combined vehicle 18A and 18B is placed on floor 34A and vehicle 18A drives 21A towards wall 34B, vortex generator IB (not shown) Is activated after vehicle 18B has turned through 90° and is located on the wall 34B (vortex generator 1A need not be started on floor 34Ά unless the encash loading of vehicle 1 B (Figure 7) would otherwise overbalance vehicle 1SA.) When vortex generator I B is established, vehicle 18B starts climbing up 216 wall 348. Vortex generator 1A is activated when vehicle ISA has turned through 9G° and is located on the wall 34B. The combined vehicles can then traverse along wall 34B. When moving from the ceiling 34C to the wall 348, vehicle 18A drives 21A vehicle 138 towards the wall, vortex generator IB is deactivated as vehicle 1 SB turns through a 90* bend from the ceiling 34G onto the wall 348. Vortex generator IB is then reactivated to attract vehicle 188 towards the wail 34B and vortex generator i-A is deactivated to allow vehicle 18A to turn 80* onto the wali 34B. in practical operations, vehicles 18A and 1:88 may be provided with a camera(s) on articulated means (not shown) to relay moving pictures to a remote viewing station (not shown) from where instructions would fee sent to the articulated arms to collect tools, or equipment from storage points (riot shown) on vehicles ISA or 188 and use it/fhem to undertake predeiarmined operations. Remotely controlled robotic operations are commonplace end the skied person will be familiar with approphate ones for particular applications.

For clarity, articulated arm(s) 26 are not shown but, when vehicle 188 executes its turn, there will be a risk of umbilical power cable 37 becoming entangled with an arm 26, Umbilical handling device 38 is provided to manoeuvre cable 3:7 to avoid entanglement, or to untahgie the cable, should entanglement have occurred, Arm(s) 26 may be moved in conjunction with handler 33, if required, Handler 38 may be provided with lateral rotational and telescopic freedom of movement, as required.

A vehicie may comprise a drill for drilling the surface on which the vehicle is located of an alternative item. Trie drill, may be held by an articulated arm 26 or other suitable mounting: apparatus. The vehicle may comprise anti-vibration means for limiting or minimising the transfer of drilling vibration to other parts of the vehicie. The vehicle may comprise debris collecting means arranged to collect debris generated during the drilling process. Figure 11 depicts a practical example of the capabilities of the apparatus of the invention where a vehicle 18 could climb a wail 23 to a predetermined point, use its articulated arm 28 tc retrieve a drill 39 from its storage location (not shown), fit an appropriate size of bit and drill ¾a hole in wall 23. A vehicie 18 might be used for drilling in a nuclear decommissioning application to assess radioactive contamination in concrete containment walls 23. This could Involve -drilling 39, say, 1 _. 0mm Into the wall, using a drill such as a linear actuator 40, and collecting the debris from the: hole in a container (not shown); this could be stored for subsequent analysis or an on-board detector could measure the radiation directly and report the reading In real time, if the reading was too high, it would drill 39 in, say, another 5mm 40 and repeat the sampling. In this way, the Decommissioning Personnel would know how deep the contamination had penetrated and what thickness of concrete had to be removed. (Debns collection pots and radiation detection means are not shewn in Figure 11 to avoid confusing detail. It will be noted that drill 39 is operated below vehicle 18 so that debris from the hole is not ingested into vortex generator 1 (not shown). Debris collection pot (not shown) could be mounted on and below drill 39, )

On completion of this task, vehicle 18 eooid undertake further tasks or remain perched on wail 23 monitoring the environment and awaiting .further instructions. Figure 12 shows vehicle is, provided with a universal handling means 41, Arrows 42 indicate lateral, translational and rotational movement capabilities and a universal mounting (not shown} on chassis 7 gives the further degrees of freedom required to held tools, etc. and so to perform a wide range of operations.

One problera when vehicles climb waits 23 in industrial facilities Is that pipes 4®, etc often run across, or dlose to, walls. Figure 13 shows . how two vehicles 18G and 18D may be connected by 3 coupling means 43. The coupling means 43 is rotatable 44 about pivots 4S;A and 45B and is telescdoie 44, When vehicle ISC reaches pipe 48, doth vehicles i«C and 18P would stop. Vortex generator 10 (not shown) in vehicle ISC is switched off allowing vehicle 18Ό to move vehicle ISO, using coupling means 43, off wall 23 to a distance to clear pipe 48. Coupling means 43 is extended 44 and lowered to allow vehicle 1SC to be replaced against wall 23 and vortex generator 1G restarted, When this has restored vehicle 18C's grip on wall 23, vehicle 18D then moves up to pipe 46, vortex generator 10 (not shown ) in vehicle 18D is switched oft allowing; vehicle ISC to lift vehicie LSQ, using coupling means 43, clear of wail 23, move upwards and replace it on wall 23.

Coupling means 43, with Its multiple decrees of freedom 44 and 4SA and 45B allow a pair of vehicles 18C and 18D to negotiate a wide range of obstacles, e,g. climb the outside of a cupboard and move onto Its top surface, Coupling means 43 can be designed to; suit a variety of specialised duties, e.g. elimbincs a house wall, reaching around the _: guttering and transferring onto the roof.

Whilst endeavouring in the foregolng specification to draw attention Id those features of the invention believed to he of particular importance, it should be understood that the applicant claims; protection in respect of any patentable feature or combination of features referred to herein arid/or shown in the drawings, whether or not particular emphasis has been placed on them.

Throughout the description and claims of this specification, the words "comprise" and "contain", and any variations of the words, means "including hut not limited to" and is not intended to (and does not} exclude other features, elements, components, integers or steps.

Throughout the description and claims Of this specification, the singular encompasses the pSurai unless the context requires otherwise. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise,

Features, integers or characteristics described in conjunction with a particular aspect, embodiment or example of the invention are to be understood io be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.