GB2473191A

GB2473191A - Wall Mounted Robotic Arm and Position Sensing System

Info

Publication number: GB2473191A
Application number: GB0915219A
Authority: GB
Inventors: Keith Ridgway
Original assignee: University of Sheffield
Current assignee: University of Sheffield
Priority date: 2009-09-02
Filing date: 2009-09-02
Publication date: 2011-03-09
Anticipated expiration: 2029-09-02
Also published as: GB2473191B; GB0915219D0

Abstract

A manufacturing structure 10 comprises a building having floors 16, walls 12 and roof 14, one of the walls constituting a base 32 for a machine tool comprising an arm 30 attached to the base, the other end 34 mounting a tool bit 36 e.g. a drill or gripping means, incorporating a first receiver 20a, a second receiver 20b being mounted on the workpiece 40, a space positioning system using the receivers to allow automatic positioning of the tool bit by a computer system 24. The space positioning system may use GPS or radio signals and may have at least three transmitters 18 and may be augmented by a laser positioning system. The arm may be a flexible robot arm. There may be other machine tools also automatically controlled and fixed to tracks or to the floor. A platform may be provided for factory personnel. The structure may be used for any manufacturing process such as drilling, milling, applying carbon fibre etc and may provide a concept factory, manufacturing one-off large items or components e.g. wings for the energy, nuclear, aerospace, marine, transport or defense sectors.

Description

MANUFACTURING STRUCTURE

[0001] This invention relates to a structure for the manufacture of large components, such as wing sections of airplanes or blades of wind turbines. Such components may be tens of metres in dimension. When large components require machining or other operations performed on them, despite their large size, extreme accuracy is often required.

BACKGROUND

[0002] In machining of any object (workpiece) it is normal practice to position the workpiece precisely on a table. The table generally has a pillar rigidly fixed to it with an arm adjustably fixed on the pillar. The arm has a machining point, being the point of application of the task in hand. The task is typically something as simple as drilling a 6 mm hole, but it may equally be something more involved such as milling a particular shape, or applying carbon fibre. The machining point is generally at a precisely known position at all times with respect to a datum point on the table. When the workpiece is accurately located on the table, the control system knows precisely how to manoeuvre the arm to effect the requisite machining operation. With small workpieces, this is a perfectly satisfactory arrangement, and the machine comprising the table, pillar and arm is of manageable proportions. However, the system depends on the rigidity of the pillar and arm. Again with a small machine, it is not a significant problem to achieve high accuracy (eg � 0.001 mm). When the system is scaled up for larger and larger workpieces, it is found that the pillar and arm need to become more and more massive in order to exhibit the requisite degree of rigidity and so that the machining point is precise over the entire working envelope of the table. Indeed, external parameters such as temperature and humidity become even a more significant and must be closely controlled. It is found that, for large work pieces, equipment weighing many tons and costing many thousands of GB pounds is needed, even for something as basic as drilling 6 mm holes.

[0003] It is known to augment machining equipment by attaching lasers to the machining point. The laser light beam is reflected off the workpiece and detected so that adjustments to the position of the arm can be made to direct the machining point to a specific location on the work piece. Nevertheless, the arm itself must be rigid to maintain location during machining and resist any reaction of the workpiece. Again, it is emphasised that throughout this specification, the term "machining" is to be construed in its broadest sense as meaning any action performed on a workpiece by a machine, whether, drilling, milling broaching or other material removal, or any other action not involving removal of material from the workpiece but even mere modification of material (eg peening) or addition of material (eg welding or coating, for example with carbon fibre).

[0004] Wide space positioning arrangements are also known using radio signals and triangulation. Global Positioning System (GPS) is the name for the system of positioning employing satellites that transmit signals from space to the ground and, provided a receiver can receive signals from three or more satellites, a triangulation of the position of the receiver permits relatively precise identification of the position and orientation in space of the receiver.

However, more localised arrangements are also known, for example in WO-A-such a system is employed in a container handling system at a quayside and so as to track the position of containers between sea vessels, land vehicles and a temporary container storage location by tracking movement of their handling equipment using GPS.

[0005] It is an object of the present invention to provide a manufacturing structure that does not depend on large machine tools to permit accurate working on relatively large objects.

BRIEF SUMMARY OF THE DISCLOSURE

[0006] In accordance with the present invention there is provided a building having floors, walls and roof, in which at least one of the walls constitutes a base of a machine tool arranged to machine a workpiece in the building, the machine tool comprising an elongate arm connected to said base and its other end mounting a tool bit incorporating a first receiver, a second receiver mounted on the workpiece, and a space positioning system within the building, wherein a computer system controls the position of the tool bit with respect to the workpiece by means of said position sensing system identifying the position and orientation of the tool bit and workpiece with respect on one another.

[0007] Preferably, a laser position system augments the space positioning system, whereby a laser beam is directed from a source on the arm to the workpiece on which a mark is disposed at a position fixed with respect to a desired work location on the workpiece, and a detector on the arm to detect reflection from the workpiece, the laser position system being able to recognise a reflection from said mark.

[0008] Preferably, reaction means are disposed on the arm to enable the arm to fix to said workpiece. Preferably, said reaction means comprise the arrangements claimed in our co-pending United Kingdom application number 09 the entire contents of which are hereby incorporated by reference.

[0009] Preferably, said space positioning system is a radio signal positioning system with at least three radio transmitters spaced from one another covering the working space within the building and said receivers being radio receivers capable of identifying the direction from which the radio signals emanate and transmitting such information to the computer system.

[0010] The working space is that volume of the building in which machining operations may be conducted on the workpiece by the machine tool.

[0011] Preferably, there is a plurality of machine tools disposed in the building also under the control of the computer system. Some of said machine tools may have a base comprising the floor of the building. Some of said machine tools may have a base comprising a track disposed on the floor and/or walls of the building. Some of said machine tools may comprise conveying means.

[0012] It is suggested that there is an increasing need for large-scale pilot manufacturing facilities that will enable both large companies and SMEs to develop and manufacture products up to first production prove out stage, that is, beyond the prototype stage and up to the point where the full process can be taken and completely transferred into a commercial manufacturing facility.

[0013] Thus, the present invention may be considered a "Concept Factory", which is capable of manufacturing and assembling large components and structures used in the aerospace, nuclear, energy, marine, defence and transport sectors up to the first part prove out stage.

[0014] When manufacturing large components, one of the large cost factors is the depreciation of machine tools and equipment. This is, of course, factored over the life of the product, but it is still a considerable cost, which is ultimately absorbed into the component selling price. Manufacturing large components in traditional factories requires large expensive machine tools, but often these machine tools are only carrying out trivial machining operations and it is the component size and positional accuracy, rather than machining difficulty, which governs the size of the machine tool. However, technology has moved on considerably in recent years and laser projection, laser and optical guidance, laser scanning and indoor global positioning systems have all become mature technologies. Positional accuracy can now be determined over extremely large components using these technologies. Instead of building large, heavy and rigid machine structures, the present invention suggests the use of much lighter machine tools and robots, and integrate the machine structure into the fabric of the building. Instead of machining a 20m long component on a 20m long machine tool, it is possible to position the component on the factory floor and accurately measure and position robotic arms to machine or drill the component.

[0015] Given the flexibility of robotics it is also possible to provide a highly flexible and adaptive facility, which can use robotics and new positional accuracy and damping technologies to change from a metal cutting machine tool to an assembly drilling and fixing tool to a composite layup or trimming tool. The robots can be attached to the floor, ceiling or walls of the factory and their accuracy and performance can be controlled by feedback from the GPS or laser guidance systems.

[0016] Thus the vision of the "Concept Factory' is to build a large building with an integrated structure which has the capability to machine large nuclear power station components, build wind turbines and assembly small aircraft and wings. This will enable companies to enter new markets and develop new methods of manufacturing and assembling large structures and components, possibly with a reduction in total manufacturing costs by in excess of 25%.

[0017] The concept factory will have several unique features, which will: * Focus on low energy manufacturing technologies * Integrate the machine tool, assembly and building structure * Enable highly flexible and adaptable systems to be used, which are capable of manufacturing AND assembling components such as an aircraft wing, a wind turbine blade, a defence vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the invention will now be described, byway of example only, with reference to the accompanying drawings, in which: Fig. 1 is a schematic view of a manufacturing structure in accordance with the invention; Fig. 2 is an internal end perspective view of a structure in accordance with the invention; Fig. 3 is an external view of a potential building in accordance with the invention; and Figs 4 to 7 are part of the Appendix hereto and are described therein.

DETAILED DESCRIPTION

[0019] Referring now to Fig. 1, a manufacturing structure in accordance with the invention is exemplified by structure 10 having walls 12, ceiling 14, and floor 16. GPS beacons 18 are disposed in various locations of the building to emanate radio waves so that they overlap in most areas of the building, a working volume of the building. In different locations, receivers 20 may be disposed which receive signals from the beacons 18 and which are arranged so that the direction of the strongest signal from each beacon 18 can be determined, and whereby both the position and orientation of the receivers 20(a,b) within the structure 10 can be precisely determined. The receivers are themselves in communication with a central computer system 24 which is capable of mapping the structure 10 and determining the inter relation between the different receivers 20 within the structure.

[0020] Within the structure 10 are fixed various robot arms 30 (only one of which is shown) that are connected to walls 12, or floor 16, or ceiling 14 as the case may be. Indeed, the location of the base 32 of the robot arm may be moveable on its support. The robot arm is flexible and has a working end 34 carrying a tool bit 36. The tool bit may be a drill. However, within the context of the present invention, the tool bit 36 may be any tool, for example a gripping means by which to grasp and manipulate a work piece.

[0021] A work piece 40 is shown in Fig. 1, which here comprises a wing section of an airplane or a blade for a wind turbine. The arm 20 has one of the receivers 20 (here 20a) fixed on it, precisely located with respect to the tool bit 36. Thus, knowing the precise location and orientation of the receiver 20a is the same as knowing the precise location and orientation of the tool bit 36.

[0022] Likewise, the work piece 40 has a receiver 20b fixed to it so that the position and orientation of all points of the work piece are also known. Thus, if it is required to drill a hole at a point 50 on the work piece and the location of the point 50 in relation to receiver 20b on the work piece 40 is known, then the computer 24 can direct movements of the robot arm 30 SO that the tool bit can precisely be positioned adjacent the point 50 with the direction of the tool bit 36 appropriately aligned.

[0023] Indeed, it may be desirable, when more than millimetric precision is required in the position of the tool bit 36 with respect to a target point 50, that a mark 52 is disposed on the work piece at a precise position with respect to the target point 50. A laser guidance arrangement 54 may be disposed on the robot arm 30. The laser guidance arrangement 54 comprises a laser beam source and reflection detection system, wherein the beam is directed towards the target 52 and the reflection is detected, whereby the precise location of the laser system 54, and thereby the tool bit 36, can be accurately determined.

[0024] The flexibility of the robot arm 30 is not problematic with regard to accurate positioning of the tool bit 36 within reasonably long time frames. However, in machining a work piece, such as the wing section 40, there are two issues that need to be addressed. The first is the reaction of the work piece to the machining operation being effected, and secondly the possibility of vibration occurring at high frequency.

[0025] The former changes in a relatively short time frame, but even then, the position changing arrangements comprising position detection, determination of new position desired and instructions to move the arm to the desired position, may be sufficiently responsive to accommodate tool reaction forces. However, vibration happens in too short a time frame for the system of the present invention do anything to resist. Normally, the stiffness of the robot arm is increased, so that both these issues can be accommodated by the increased stiffness of the arm.

[0026] However, in our co-pending UK application no. 0913830.6 filed on 7 August 2009 under the title of "Confined Space Drill" there is discloses an arrangement whereby a compact arrangement of a drill is provided, as well as a reaction mechanism for connecting the robot arm 30 to a work piece around a target area 50 so that the effects of work piece reaction and vibration can be handled without losing positional accuracy. Selected extracts from the above mentioned application are attached as an appendix hereto and figures a to b from that specification are attached as the corresponding figure numbers hereto.

[0027] Turning to Figures 2 and 3, manufacturing structure 10' is illustrated wherein the floor, walls and ceiling are oval shaped in cross section, with a platform floor 16a provided for personnel 100 operating the factory. Throughout the length of the manufacturing structure, tracks 60 are provided extending from floor 16 around wall 12 and into ceiling 14 and on which robot arms 30 are moveably disposed. The tracks 60 enable the position of the robot arms to be varied within the space of the structure 10'. In figure 2, two robot arms 30a,b are shown handling a turbine blade 40'. Indeed, in the case of turbine blades, the construction thereof involves the application of carbon fiber strips, cemented to the skeleton of the blade and the basic requirement of such an arrangement is flexible positioning and manipulation of the blade skeleton with reasonably precise application of the strips. The present structure facilitates such a process.

[0028] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. 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.

[0029] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0030] The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Appendix Remote Confined-Space Machining, and Positioning and Securing Arrangement [0031] This invention relates to a system for positioning and holding a machine for working in a confined space at a distance from a support base. It relates to means rendering the machine compact, but also secure in a correct position. In another aspect, it relates to mounting structure being an arrangement of a mechanism for permitting adjustment of the position of any device laterally with respect to a substrate to which the device is connected.

Appendix -BACKGROUND

(00321 It is often required to machine a component somewhat remotely. This is becoming more common in advanced manufacturing, particularly in the aeronautic industries where the tendency is towards larger and larger monolithic components. Large monolithic components have fewer joints that can be a source of weakness. Nevertheless, while this may reduce the need for machining of components, it does not entirely remove it, and it may render what is needed somewhat more complex. Even multiple component parts often require machining in hard-to-reach places after their initial construction. Wing parts are a case in point.

(00331 However, robot arms are versatile and flexible and can carry machine tools into hard-to-reach places. Remote optics or other guidance can precisely position the end of a robot arm. There are several issues that need to be addressed. First of all, the tool at the end of a robot arm must be compact; first, to fit into any confined space, but secondly to be able to position a working tool bit of the tool in selected positions in the confined space. Next, although, ultimately, precise positioning is perfectly possible, it is difficult to move a remote arm, if it is long and flexible, without small movements being exaggerated at the tool head by the flexibility of the arm and the distance of the tool head from the stable base of the robot.

(00341 When machining components it is invariably necessary to provide a reaction member against which the tool performing the machining can react in response to loads imparted by the workpiece in reaction to the action of the machining tool. However, in hard-to-reach places, providing such reaction member is often problematic. One approach is to employ a rigid mounting for the machining tool, but in confined spaces, maneuvering such a member is a problem and may limit the position at which the tool can be located. However, employing a more slender mounting reduces the stiffness and reaction force that can be applied.

(00351 It is known to use the workpiece itself as a steady reaction base. By clamping the tool to the workpiece, it does not matter if the tool working bit moves uncontrolled with respect to the ground, provided it maintains a true relationship with the workpiece. However, such an arrangement requires a means of advancing the tool working bit into or against the workpiece, increasing the bulk and complexity of the tool head.

(00361 Furthermore, controlling the position of the tool working bit while any such clamp is activated is difficult. It involves predicting the position of the tool working bit once the clamp is effected; and that depends, to a large extent, on the nature of the workpiece, which inevitably varies from case to case. Connecting such a clamp to a workpiece in a confined space is another problem.

Appendix -BRIEF SUMMARY OF THE DISCLOSURE

(00371 In accordance with the present invention there is provided a machining tool comprising: a frame mounting an extendable yoke slidable with respect to the frame in a first direction through at least one mounting pillar, a tool motor mounted on the yoke and having a tool bit to machine a workpiece a chassis plate connected to the frame beyond the yoke and through which the tool bit can protrude a foot plate having attachment means for attaching to the workpiece, and locking means to lock the chassis and foot plates together in selectable position within a plane containing said plates and inclined to said first direction, whereby the tool can be fixed with respect to the workpiece for reaction against the workpiece during machining of the workpiece by the tool.

(00381 Preferably, said attachment means comprises a selectively actuable suction foot.

Preferably, said locking means comprises a selectively actuable electromagnet on one of said chassis and foot plates that, when actuated, attracts a keeper on the other of said chassis and foot plates, clamping said plates together. Said keeper may comprise a ferromagnetic washer around a leg connecting said chassis plate to the frame, the leg extending through an aperture of the foot plate that permits lateral movement of the foot plate with respect to the chassis plate when said electromagnet is not actuated. Said keeper may be spring biased against said foot plate to press said chassis and foot plates together so that they slide against one another when one is moved with respect to the other in a direction parallel said plane that contains them.

(00391 Preferably, said plates are non-ferromagnetic. Preferably, the tool is a drill. Indeed, preferably, the tool according to the second aspect of the present invention is also a tool having one or more features of a tool according the first aspect, and vice versa.

(00401 Preferably, in either aspect of the present invention, the frame has means enabling connection to a robot arm. Thus, in use, a robot arm mounting the tool is capable of being manipulated into numerous hard-to-reach locations, according to the flexibility of the robot arm and the compactness of the tool. According to the first aspect of the present invention, the tool is rendered comparatively compact so that smaller spaces can be accessed by the tool on the end of the robot arm. In the case of the second aspect, the arrangement permits a robot arm to position approximately the tool with respect to the workpiece using any positioning system as may be provided. For example, the workpiece may be transparent or not entirely enclosed, enabling direction observation of the position of the tool. Alternatively, a camera, and a light, may be mounted on the tool, enabling observation remotely. In any event, the tool is positioned approximately in the correct location for the machining operation to be effected.

Then, the attachment means are actuated and the tool, or at least the foot plate, is firmly connected to the workpiece. The workpiece will itself be connected to ground, as is the base of the robot arm. Finally, any required fine adjustment of the position of the tool with respect to the work piece can be made without the flexibility of the arm accentuating any intended movement, given the attachment of the foot to the workpiece. Once the correct position is achieved, the locking means are also actuated and machining can begin.

(0041J Preferred features include: * the tool is one according to the first aspect of the present invention; * the locking means comprises at least one of the plates being ferromagnetic and disposing electromagnets on the remote side of the other plate, whereby the two plates are capable of being locked together when the magnets are energized; * the electromagnets are gradually energisable to provide resistance and damping of relevant movement between the plates; * another form of damping between the plates is provided; * the plates are planar, and slide over one another; * the plate plane is arranged to be parallel the substrate when the attachment means connect the tool to the substrate; * the attachment means comprise a vacuum system; * columns connect the frame to the chassis plate, the columns passing through windows of the foot plate which is disposed between the chassis plate and frame; * at least a tool bit of the machine tool extends through overlapping apertures in the chassis and foot plates.

(00421 Preferably, the machine tool defined above has some or all of: * a camera associated therewith, whereby a substrate to be machined may be viewed remotely; * the association being remote through the agency of an optic link terminating at the tool; * the optic link comprises an optic fibre; * lubrication dispensing means, to lubricate the tool in operation; * chip extraction means to collect chippings and swarf generated by the machining operation (00431 Once approximately positioned the attachment means can be activated to connect the tool to the workpiece. Fine control of the position of the tool bit can be effected by first releasing the locking means and then adjusting the position of the remaining components relative to the workpiece while the foot plate is connected to the workpiece. Especially if damping between the chassis and foot plates is provided, jerky movements, or what might become jerky movements of the tool at the end of a long robot arm, can be accommodated and the locking means energized to stop relative movement between the plates when the tool is positioned precisely. The camera assists in this task.

(00441 Potentially, there are a number of cables and conduits that need to be connected to the tool, and run down a robotic arm: * a cable to carry power and command signals to the tool and drive motors; * an optic fibre or cable for power and command of the camera if that is mounted on the machine tool; * a cable for powering illumination at the tool; * a conduit carrying lubrication and cooling fluid; and * a conduit for extraction of swarf and used lubrication.

(00451 In accordance with another aspect of the present invention there is provided a mounting structure comprising an annular plate having an aperture and a foot plate fixed and sealed together at their external peripheries, and a base plate received between them and sealed to each plate around its periphery, thereby to define an annular chamber between the annular and foot plates in which a rheological fluid is disposed, the base plate being connectible to a first device through the aperture of the annular plate and the foot plate being connectible to a second device, which first and second devices are to be positioned with respect to one another and adjustable in position with respect to one another in a surface parallel the surface of interaction between the annular, foot and base plates, wherein activation of said rheological fluid to render it solid serves to lock the devices with respect to one another, while deactivation of the rheological fluid to render it liquid serves to permit the position of the devices to be adjusted with respect to one another by sliding the base plate between the annular and foot plates in said surface of interaction.

(00461 Preferably, said surface of interaction is planar. However, it may be spherical.

Indeed, it may be cylindrical, or even conical, but this limits the adjustment possible to just one, or possibly two directions, that is, circumferential with respect to cylindrical or conical interaction surfaces, or axially also in the case of cylindrical surfaces. Preferably, when the rheological fluid is not activated, the base plate has an infinite number of degrees of freedom of movement within the interaction surface and with respect to the annular chamber.

(00471 Preferably the rheological fluid is magnetorheological, whereby generation of a magnetic field adjacent the annular chamber solidifies the fluid. Alternatively, the rheological fluid is electrorheological, whereby generation of an electric field adjacent the annular chamber solidifies the fluid.

Appendix -BRIEF DESCRIPTION OF THE DRA WINGS

(00481 Embodiments of the different aspects of the present invention are further described hereinafter with reference to the accompanying drawings, in which: Figure 4 shows a rear perspective view of a tool incorporating features of the present invention; Figure 5 is a front perspective view of the arrangement shown in Figure 4; Figure 6 is a rear perspective, partly sectional view of a mounting structure in accordance with another aspect of the present invention; and Figure 7 is a rear perspective view of the structure shown in Figure 6.

Appendix -DETAILED DESCRIPTION

(00491 Turning to Figure 4, the tool 10' illustrated therein is supplemented by an attachment mechanism 100, according to the second aspect of the present invention. Here, columns 102 are fixed to the frame 12, passing through apertures 104 in the yoke 28. The other ends of the columns 102 are fixed to a base plate 106, passing through apertures (not visible in the drawings) in a foot plate 108. The foot plate 108 is provided with a number of suction pads 110, selectively supplied with a vacuum source (not shown) to ports 112 and by means of which the pads 110 may be applied to and held in contact with a substrate or workpiece (not shown).

(00501 The base plate 108 is provided with a recess 114 to allow passage of the drill bit 36 without interference thereof. The drill bit also passes through a small aperture 116 that is sized to accommodate the largest drill bit 36 that might be employed by the tool 10'. The base and foot plates 106, 108 are planar, disposed perpendicularly with respect to the axis 50 of the drill bit 36. Washer plates 118 are slidably disposed on the columns 102 and are pressed into engagement against the back of the foot plate 108 by springs 120 disposed on the columns 102 and held in place by grip rings 122. Thus, the plates 106,108 are urged together by the washers 118 but only so as to permit them to slide against one another in their plane, perpendicular to the axis 50.

(00511 The foot plate 108 is ferromagnetic, whereas the base plate 106 is not. The base plate 106 mounts on its under-surface a plurality of electromagnets 124. When these are energised, the base plate and foot plate are firmly clamped together by attraction of the base plate 108 by the magnets 124. Thus, in use, the tool 10' is offered up to the workpiece with the base and foot plates in a central juxtaposition with respect to one another, the magnets 124 being energised so that no relative movement between the two plates is possible. When the tool 110 is positioned against the substrate with the suction feet 110 resting against a planar surface of the workpiece and in the approximate position where it is desired to drill a hole, the suction feet 110 are activated. The foot plate 108, therefore, becomes fixed with respect to the workpiece. However, by virtue of the potential inaccuracies of the positioning system, the precise position of the drill bit 36 with respect to the workpiece may not be precise.

An optical system (not shown) might verify this. In this event, the electromagnets 123 are de-energised, but without releasing the foot plate 108 and suction pads 110. Now, within the confines of the recess 114 and the apertures (not visible) in the foot plate 108 through which the columns 102 pass, the position of the tool 10' can be adjusted laterally, that is to say radially, with respect to the axis 50. The foot plate may not be ferromagnetic, in which case, the washers 118 may be ferromagnetic, instead, and the magnets 124 be disposed opposite them to attract them to effect the requisite clamping.

(0052J Assuming that an accurate positioning system is available, the precise location of the drilling bit 36 can be assured, whereupon the electromagnets 124 are re-energised to fix the position. Thereafter, the motor 30 can be started to commence drilling, and the drive mechanism 40,56 invoked to advance the drill bit 36 into the workpiece. The mounting arrangement 100 provides reaction for the tool against the loads imposed by the drilling operation.

(00531 The positioning system and other support systems are not part of the present invention, but only subsidiary to it. If the tool is intended to be employed in enclosed spaces at the end of a robot arm, as presently proposed, then it is likely that a camera will be employed to enable accurate positioning of the tool with respect to the workpiece. The camera (not shown) may be mounted directly on the tool, but equally, it may be mounted remotely, with an optic fibre link or other transmission arrangement supplying an image of the workpiece to the camera. A camera also presupposes a source of light to illuminate the workpiece, and this likewise may be remote and the light transmitted by optic fibre or the like. Alternatively, a;light source may be mounted on the tool. Several electrical links to the tool are needed, to power the main drive motor 30, as well as the advancement motor 40, as well as any additional control arrangements. Various conduits may be provided, one to supply cooling and lubricating medium to the drill bit, and another to collect used medium, as well as cuttings swarf from the drilling operation. While drilling is described, other machining operations are feasible.

(00541 In Figure 6 is illustrated a support structure 200 that can take the place of the support structure 100 described above with reference to Figures 3 and 4. Here, a base plate 106' has columns 102' fixed thereto. A composite foot plate 108' comprises an annular plate 202 having an aperture 204 through which the columns 102' pass, and a foot plate 206 which is also annular having a central aperture 208. The necessity for the aperture 208 depends upon the application. For a drilling base, as described above, it is necessary to allow passage of the drill bit. However, for other applications this aperture 208 might not be required. Foot attachment means 110' are fixed to the foot plate 206 by rods 210. The attachment means 110' may comprise a suction arrangement, provided with a suction port 112', similar to the embodiment described above with reference to Figures 3 and 4. The annular and foot plates 202,206 are fixed together by a rim element 212 that is provided with internal castellations 214 described further below. The base plate 106' is received between the annular plate 202 and foot plate 206 and is sized so that, when one edge 106a touches the castellations of the rim 212, the opposite edge 106b is still between the plates 202, 206. Around each internal periphery of the apertures 204, 208 the annular plate 202 and the foot plate 206 are each provided with an annular 0-ring seal 220. Thus, between the annular plates 202, 206, the rim 212 and the base plate 106' an annular chamber 222 is defined. The chamber 222 is filled with a rheological fluid, which may be magnetorheological or electrorheological. When the rheological fluid is liquid, the base plate 106' is a close sliding fit between the plates 202,206 and they can slide to any position with respect to one another within the confines permitted by the rim 214 and the columns 102'. However, when the rheological fluid is activated, either by a magnetic field or an electrical field, as the case may be, the fluid in the chamber 222 turns solid and locks the base plate 106' in position with respect to the composite foot plate 108'.

When activated, the rheological fluid turns solid and keys with the castellations 214.

Corresponding castellations may be provided on the external periphery 106b of the base plate 106'. However, ferrous elements or tongues 224 may be provided in the edge 106b to interact with the rheological fluid.

(00551 Indeed, while the arrangement has an evident application in the field of machining and drilling, as described above with reference to Figures 1 to 5, the mounting structure 200 may have broader application. In that event, the rheological fluid may not merely be employed for locking the base plate 106' with respect to the foot plate 108', but may also be employed to selectively damp relative movements between them in the plane that contains them. To this end, there is no limitation of the devices that can be attached to each plate. For drilling purposes, not only is the aperture 208 provided in the foot plate 206 to allow access of the drill bit 36, but also a hole 116' is required for the same purpose.

Appendix -Claims 21. A machining tool comprising: a frame mounting an extendable yoke slidable with respect to the frame in a first direction through at least one mounting pillar, a tool motor mounted on the yoke and having a tool bit to machine a workpiece a chassis plate connected to the frame beyond the yoke and through which the tool bit can protrude a foot plate having attachment means for attaching to a workpiece, and locking means to lock the chassis and foot plates together in selectable position within a plane containing said plates and inclined to said first direction, whereby the tool can be fixed with respect to the workpiece for reaction against the workpiece during machining of the workpiece by the tool.

22. A machining tool as claimed in claim 21, wherein said attachment means comprises a selectively actuable suction foot.

23. A machining tool as claimed in claim 21 or 22, wherein said locking means comprises a selectively actuable electromagnet on one of said chassis and foot plates that, when actuated, attracts a keeper on the other of said chassis and foot plates, clamping said plates together.

24. A machining tool as claimed in claim 23, wherein said keeper comprises a ferromagnetic washer around a leg connecting said chassis plate to the frame, the leg extending through an aperture of the foot plate that permits lateral movement of the foot plate with respect to the chassis plate when said electromagnet is not actuated.

25. A machining tool as claimed in claim 23 or 24, wherein said keeper is spring biased against said foot plate to press said chassis and foot plates together so that they slide against one another when one is moved with respect to the other in a direction parallel said plane that contains them.

26. A machining tool as claimed in any of claims 23 to 25, wherein said plates are non-ferromagnetic.

27. A machining tool as claimed in claim 21 or 22, wherein the locking means comprises at least one of the plates being ferromagnetic and disposing electromagnets on the remote side of the other plate, whereby the two plates are capable of being locked together when the magnets are energized.

28. A machining tool as claimed in any of claims 23 to 27, wherein the electromagnets are progressively energisable to provide resistance and damping of relevant movement between the plates.

29. A machining tool as claimed in claim 21 to 28, wherein the plates are planar, and slide over one another.

30. A machining tool as claimed in claim 29, wherein the plate plane is arranged to be parallel the substrate when the attachment means connect the tool to the workpiece.

31. A machining tool as claimed in any of claims 21 to 30, wherein columns connect the frame to the chassis plate, the columns passing through windows of the foot plate which is disposed between the chassis plate and frame.

32. A machining tool as claimed in any of claims 21 to 31, wherein at least a tool bit of the machine tool extends through overlapping apertures in the chassis and foot plates.

33. A machining tool as claimed in any of claims 21 to 32, comprising a tool as claimed in any of claims 1 to 20.

34. A machining tool as claimed in any preceding claim, wherein the frame has means enabling connection to a robot arm.

35. A machining tool as claimed in any preceding claim, wherein a camera is associated with the tool, whereby a substrate to be machined may be viewed remotely.

36. A machining tool as claimed in claim 35, wherein the association is remote through the agency of an optic link terminating at the tool, preferably an optic fibre.

37. A machining tool as claimed in any preceding claim, further comprising lubrication dispensing means, to lubricate the tool in operation.

38. A machining tool as claimed in any preceding claim, further comprising chip extraction means to collect chippings and swarf generated by the machining operation.

39. A mounting structure comprising an annular plate having an aperture and a foot plate fixed and sealed to the annular plate around an external periphery, and a base plate received between the annular and foot plates and sealed to each plate around an internal periphery, thereby to define an annular chamber between the annular and foot plates and said internal and external peripheries in which a rheological fluid is disposed, the base plate being connectible to a first device through the aperture of the annular plate and the foot plate being connectible to a second device, which first and second devices are to be positioned with respect to one another and adjustable in position with respect to one another in a surface parallel the surface of interaction between the annular, foot and base plates, wherein activation of said rheological fluid to render it solid serves to lock the devices with respect to one another, while deactivation of the rheological fluid to render it liquid serves to permit the position of the devices to be adjusted with respect to one another by sliding the base plate between the annular and foot plates in said surface of interaction.

40. A mounting structure as claimed in claim 39, wherein said surface of interaction is planar.

41. A mounting structure as claimed in claim 39, wherein said surface of interaction is spherical.

42. A mounting structure as claimed in claim 39, wherein the rheological fluid is magnetorheological, whereby generation of a magnetic field adjacent the annular chamber solidifies the fluid.

43. A mounting structure as claimed in claim 39, wherein the rheological fluid is electrorheological, whereby generation of an electric field adjacent the annular chamber solidifies the fluid.

44. A mounting structure as claimed in any of claims 39 to 43, wherein said foot plate is also annular.

45. A machining tool as claimed in claim 21 or 22, wherein said chassis plate comprises the base plate of a mounting structure as claimed in any of claims 39 to 44, said foot plate comprises the foot plate of said mounting structure, and said locking means comprises means to selectively activate and deactivate said rheological fluid of the mounting structure.

46. A machining tool as claimed in claim 45 and claim 31, wherein said windows comprise the aperture of the annular plate of said mounting structure.

47. A machining tool as claimed in claim 44 or 45 that is also a machine tool as claimed in any of claims 32 to 38, other than when dependent on any of claims 23 to 28.

48. A machining tool, substantially as hereinbe fore described with reference to the accompanying drawings.

49. A mounting structure, substantially as hereinbe fore described with reference to the accompanying drawings.

Claims

CLAIMS1. A manufacturing structure comprising a building having floors, walls and roof, in which at least one of the walls constitutes a base of a machine tool arranged to machine a workpiece in the building, the machine tool comprising an elongate arm connected to said base and its other end mounting a tool bit incorporating a first receiver, a second receiver mounted on the workpiece, and a space positioning system within the building, wherein a computer system controls the position of the tool bit with respect to the workpiece by means of said position sensing system identifying the position and orientation of the tool bit and workpiece with respect on one another.
2. A structure as claimed in claim 1, in which a laser position system augments the space positioning system, whereby a laser beam is directed from a source on the arm to the workpiece on which a mark may be disposed at a position fixed with respect to a desired work location on the workpiece, and a detector on the arm to detect reflection from the workpiece, the laser position system being able to recognise a reflection from said mark.
3. A structure as claimed in claim 1 or 2 in which reaction means are disposed on the arm to enable the arm to fix to said workpiece.
4. A structure as claimed in claim 3, in which said reaction means comprise the arrangements claimed in co-pending United Kingdom application number 0913830.6 and as set out in the Appendix hereto.
5. A structure as claimed in any preceding claim, in which said space positioning system is a radio signal positioning system with at least three radio transmitters spaced from one another covering the working space within the building and said receivers being radio receivers capable of identifying the direction from which the radio signals emanate and transmitting such information to the computer system.
6. A structure as claimed in any preceding claim, in which there is a plurality of machine tools disposed in the building also under the control of the computer system.
7. A structure as claimed in claim 6, in which at least one of said plurality of machine tools has a base comprising the floor of the building.
8. A structure as claimed in claim 6 or 7, in which at least one of said plurality machine tools has a base comprising a track disposed on the floor and/or walls of the building.
9. A structure as claimed in claim 6, 7 or 8, in which at least one of said plurality of machine tools comprises workpiece conveying means.
10. A manufacturing structure substantially as hereinbefore described with reference to the drawings.