Transfer of fabric shapes from a nest to stacks of fabric shapes, and to moulds

TRANSFER OF FABRIC SHAPES FROM A NEST TO STACKS OF FABRIC

SHAPES, AND TO MOULDS

DESCRIPTION

0004The present invention relates to the transfer of fabric shapes from a nest of fabric shapes to stacks of fabric shapes, for example during manufacture of composite products. A composite product may be formed by arranging a plurality of fabric shapes into a mould, adding a resin if no resin is already impregnated in the fabric shapes, and baking at high temperature. The fabric shapes may for example be carbon fibre shapes. The fabric shapes are typically manufactured by cutting them from a sheet of fabric, the sheet of fabric being typically unwound from a roll of fabric. Once the sheet has been cut, the fabric shapes are arranged into various stacks. Each stack typically includes the fabric shapes that are required for a particular mould. The fabric shapes of each stack are often different shapes to one another, and are stacked in a specific order, so that they can be inserted one-by-one into the mould in the correct order. Those skilled in the art may refer to the stacks as kits, and the fabric shapes as plies.

0005The fabric shapes are typically cut by a cutting machine, which makes the required cuts through the fabric sheet to define the fabric shapes. Once the fabric sheet has been cut, it may be referred to as nest of fabric shapes, since the cut fabric shapes are all nested amongst one another within the fabric sheet. A technician is then required to pick up each fabric shape from the nest, and place it into the appropriate stack.

0006The sheets of fabric from which the fabric shapes are cut can be expensive, and so there is a desire to cram as many fabric shapes as possible into any given sheet, to minimise the area of the sheet that is wasted or required to be recycled. Almost inevitably, there will be some areas of the sheet which do not form part of a fabric shape, and will go to waste or recycling.

0007Various algorithms exist which aim to fit as many fabric shapes as possible into a given sheet area, however one of the problems with this is that the shapes required for each stack will be distributed over the whole sheet, or even over multiple sheets, rather than arranged together with one another. Therefore it becomes difficult to identify which fabric shapes should be added to which stacks, and in what order.

0008One option is to print identifiers onto each one of the fabric shapes to designate which fabric shapes belong with which stacks. However, this adds an extra manufacturing step, and requires technicians to spend time hunting for the correct identifier amongst the fabric shapes until the correct fabric shape is found, particularly since the fabric shapes of each stack must be added to the stack in a specific order.

0009A known approach is to cut the fabric sheet so that the fabric shapes destined for each stack are all adjacent to one another, to ease the process of transferring the fabric shapes from the nest to the stacks. However, this results less than optimum usage of the fabric sheets.

0010It is therefore an object of the invention to improve upon the known art. According to a first aspect of the invention, there is provided a headset configured to augment a wearer of the headset's view of fabric shapes when transferring the fabric shapes from a nest of fabric shapes to stacks of fabric shapes, the headset comprising a processor and an optical device configured to overlay graphics in the wearer's field of view according to instructions from the processor, wherein the processor is configured to instruct the optical device to highlight a next one of the fabric shapes to be picked up from the nest of fabric shapes, and to highlight the stack to which the next fabric shape should be added, in response to a notification that a previous fabric shape has been placed on a previously highlighted one of the stacks. According to a second aspect of the invention, there is provided a method of facilitating transfer of fabric shapes from a nest of fabric shapes to stacks of fabric shapes, comprising receiving a notification that a previous fabric shape has been placed on one of the stacks, and in response highlighting, using an optical device of a headset, a next one of the fabric shapes to be selected from the nest of fabric shapes, and the stack to which the next fabric shape is to be added.

0011The headset allows the correct fabric shape to be identified by the user, no matter where the fabric shape is located within the nest. Accordingly, the fabric shapes may be cut into the fabric sheet in the most area-efficient manner, without any problems being caused by the fabric shapes of each stack being widely distributed over the fabric sheet. Furthermore, since the headset indicates the correct stack to which the fabric shape should be added, the fabric shape may not require any identifying information to be printed upon it.

0012The optical device may be configured to highlight the next fabric shape by overlaying an image on top of the next fabric shape in the wearer's field of view, for example the image may comprise an image of the next fabric shape. Then, the wearer can check that the shape of the image of the required fabric shape matches the shape of the actual fabric shape that the image is projected onto, as a cross-check that the correct fabric shape is being indicated. Alternatively, the image could be any arbitrary image indicating the next fabric shape that is to be picked up.

0013The image may comprise a line extending from a point in the wearer's field of view and pointing in the direction of the next fabric shape. Accordingly, the line may guide the wearer towards the location of the next fabric shape. The line may for example have an arrow pointing to the next fabric shape, or an arrowhead or other type of marker may be used. Other ways of leading the wearer to the next fabric shape may also be implemented, for example using Haptic feedback by utilizing a vibration device mounted to the headset and connected to the processor.

0014The processor may be configured to instruct the optical device to highlight at least a first subsequent one of the fabric shapes to be selected from the nest of fabric shapes, in addition to highlighting the next fabric shape, the highlighting indicating that the subsequent fabric shape is to be picked up after the next fabric shape is picked up. Then, the wearer may pick up more than one fabric shape, before walking over to the stacks and placing the fabric shapes on the stacks. The nest of fabric shapes may be supported on a cutting table where the fabric shapes were cut into the fabric sheet, and the cutting table may be many metres long, so allowing the wearer to pick up more than one fabric shape at a time may result in significant improvements in efficiency. The highlighting of the next fabric shape may be done at a same time as the highlighting of the first subsequent fabric shape, and the manner of highlighting the next and subsequent fabric shapes may be different to one another to indicate which order the fabric shapes should be picked up in. Preferably, the first fabric shape to be picked up, is the last fabric shape to be added to the stack, to ease the wearer's transfer of the fabric shapes from the nest to the stacks.

0015The headset may comprise a receiver connected to the processor for receiving information specifying positions of the fabric shapes within the nest of fabric shapes and an order in which the fabric shapes are to be picked up and placed in the stacks. Accordingly, the information may be transmitted to the headset from a server controlling the cutting of the fabric sheet, so that the information sent to the headset will correspond with the same nest of fabric shapes that a cutting device was instructed to cut. The headset highlights the stack to which each fabric shape should be added. This highlighting may be done at the same time as the highlighting of the fabric shape, or this highlighting may only be done after the fabric shape has been picked up by the wearer. The highlighting of the stack may comprise overlaying a line pointing to the stack in the wearer's field of view, and/or overlaying an image of the fabric shape on top of the stack where the fabric shape is to be placed. Alternatively, the image could be any arbitrary image indicating the stack that the fabric shape is to be added to. Once the fabric shape has been placed on the stack, a notification that the fabric shape has been placed on the stack may be issued, so that the processor knows that the following fabric shape to be picked up should be highlighted by the optical device. The headset may comprise a control interface having a button or slider, and the button or slider may be operated by the wearer to indicate that the fabric shape has been placed on the highlighted stack. The control interface issues the notification to the processor in response to the button or slider being operated. More preferably, so that the wearer does not have to locate a button or a slider on the control interface when a fabric shape is placed on a stack, the headset may be configured to detect a gesture of the wearer instead of awaiting operation of a button or slider.

0016For example, the headset may comprise accelerometers for detecting a particular head movement, or the headset may comprise a camera connected to the processor for detecting a particular hand gesture.

0017Alternatively, the processor may be configured to analyse video from the camera to automatically detect when the previous fabric shape has been placed on the highlighted stack, and to issue the notification when placement of the previous fabric shape on the highlighted stack has been detected. Then, the wearer does not need to think about making any particular gesture when the wearer has put the previous fabric shape onto the highlighted stack.

0018The processor may be configured to analyse the video from the camera to automatically detect when the next fabric shape has been picked up from the nest, and in response may highlight the first subsequent fabric shape to be picked up from the nest. Accordingly, the highlighting of the next fabric shape may be done at an earlier time to the highlighting of the first subsequent fabric shape. Once the next fabric shape, first subsequent fabric shape, and any further subsequent fabric shapes have been picked up, the processor may instruct the optical device to highlight a next one of the stacks to which the next fabric shape should be added, and then highlight a first subsequent one of the stacks to which the first

0019subsequent fabric shape should be added once placement of the next fabric shape on the first one of the stacks has been detected by the processor via analysis of the video from the camera. Once placement of the first subsequent fabric shape on the first subsequent stack has been detected, the notification may be issued, or if further subsequent fabric shapes were picked up, then the notification may be issued when the last one of the further subsequent fabric shapes has been placed on a corresponding one of the stacks. Then, the last one of the further subsequent fabric shapes may be considered to be a previous fabric shape relative to the next fabric shape(s) to be picked up. Advantageously, the processor may be configured to trigger an alarm if an incorrect fabric shape is picked up, or if a fabric shape is placed on an incorrect stack, to help assure that the transfer of the fabric shapes from the nest to the stacks is done correctly. In order for the highlighting to be displayed at the correct location within the wearer's field of view, the location of the headset may be determined using one or more sensors or transponders. For example, the nest of fabric shapes may be supported on a table in a room, wherein the room comprises a plurality of sensors for detecting a position of the headset within the room. The plurality of sensors are connected to a controller that is configured to send the detected position to the headset, so the headset can determine where the wearer is looking and therefore where the next fabric shape appears in the wearer's field of view.

0020Alternatively, the room may comprise a plurality of beacons mounted at different locations to one another within the room, and the headset may comprise a transponder connected to the processor for detecting signals from the plurality of beacons, the processor configured to detect a position of the headset within the room based on the signals from the beacons, to determine where the wearer is looking and therefore where the next fabric shape appears in the wearer's field of view. Then, there is no need for a controller to detect the position of the headset and send the position to the headset.

0021However, more preferably, the headset comprises a camera for recognising reference points within the wearer's field of view, the reference points being used to determine whereabouts the highlighting should be added in the wearer's field of view. Then, there is no requirement for electronic devices to be fitted in the room for the purpose of determining the headset's location. To help improve accuracy, it is possible that a combination of camera reference point recognition and at least one of sensors, beacons, and transponders may be used in combination.

0022The table or the room may comprise at least one registration mark, and the processor may be configured to detect the at least one registration mark in video from the camera, to determine where the wearer is looking and therefore where the next fabric shape appears in the wearer's field of view. The nest of fabric shapes may be placed in a known location on the table, and the table may be placed at a known location within the room, so that once the position of the headset is known relative to a registration mark on the table or in the room, the position of the headset relative to the nest of fabric shapes is also known.

0023It may be difficult for the camera to visually detect whereabouts the fabric has been cut, and so the provision of registration marks that are not part of the nest of fabric shapes enables the headset to determine whereabouts in the nest of fabric shapes the next fabric shape will be located. It would alternatively be possible to print registration marks onto the fabric shapes of the nest, which could be recognised by the camera, however this option is less preferred since the printing is an extra manufacturing step resulting in additional costs.

0024The registration marks allow an initial position of the headset to be determined, and the headset may comprise accelerometers so that the position of the headset can be determined based on the initial position plus any movements therefrom indicated by the accelerometers. According to a third aspect of the invention, there is provided a system comprising the room, table, and headset described above.

0025Once the fabric shapes have been transferred into the stacks, they may be subsequently transferred into moulds for forming composite products. The headset may also be used to assist in transferring the fabric shapes from the stacks into the moulds.

0026According to a fourth aspect of the invention, there is provided a headset configured to augment a wearer of the headset's view of fabric shapes when transferring the fabric shapes from a plurality of stacks of fabric shapes to a plurality of moulds, the headset comprising a processor and an optical device configured to overlay graphics in the wearer's field of view according to

0027instructions from the processor. The processor is configured to instruct the optical device to highlight a next one of the fabric shapes to be picked up from the stacks of fabric shapes, and to highlight one of the moulds to which the next fabric shape should be added, in response to a notification that a previous fabric shape has been placed into a previously highlighted one of the moulds. According to a fifth aspect of the invention, there is provided a method of facilitating transfer of fabric shapes from a plurality of stacks of fabric shapes to a plurality of moulds, comprising receiving a notification that a previous fabric shape has been placed into one of the moulds, and in response highlighting, using an optical device of a headset, a next one of the fabric shapes to be selected from the stacks of fabric shapes, and the mould to which the next fabric shape is to be added.

0028The highlighting and notifications may be generated in just the same manner as described previously for when transferring the fabric shapes from the nest to the stacks. In some cases, the previously highlighted mould for the previous fabric shape may be the same mould as the mould which is highlighted for the next fabric shape. In some of those cases, the previous fabric shape and the next fabric shape may have been picked up from the same stack as one another. The processor may be configured to instruct the optical device to highlight the mould by overlaying an image of the fabric shape on top of the mould in the wearer's field of view, the image showing the wearer whereabouts to place the fabric shape within the mould. Accordingly, the headset may assist the wearer with placing the fabric shapes into the moulds. Preferably, the size, shape, and position of the overlaid image is the same as the size, shape, and position of the fabric shape when it is in its place within the mould. According to a sixth aspect of the invention, there is provided a headset configured to augment a wearer of the headset's view of fabric shapes when transferring the fabric shapes from one or more stacks of fabric shapes to a mould. The headset comprises a processor and an optical device configured to overlay graphics in the wearer's field of view according to instructions from the processor, wherein the processor is configured to instruct the optical device to overlay an image of a next one of the fabric shapes to be placed in the mould. The image is overlaid on top of the mould in the wearer's field of view, and shows the wearer whereabouts to place the next fabric shape within the mould, in response to a notification that a previous fabric shape has been placed into the mould.

0029According to a seventh aspect of the invention, there is provided a method of facilitating transfer of fabric shapes from one or more stacks of fabric shapes to a mould, comprising receiving a notification that a previous fabric shape has been placed into the mould, and in response overlaying, using an optical device of a headset, an image of the fabric shape on top of the mould in the wearer's field of view, the image showing the wearer whereabouts to place the next fabric shape within the mould.

0030These sixth and seventh aspects of the invention are similar to the fourth and fifth aspects of the invention, except for that the stack(s) themselves do not have to be highlighted, as the stack(s) from which the mould is to be filled may be known by the wearer of the headset prior to beginning to fill the mould with the stack(s). The notifications may be provided in just the same manner as disclosed in relation to the first and second aspects of the invention. Preferably, the size, shape, and position of the overlaid image is the same as the size, shape, and position of the fabric shape when it is in its place within the mould.

0031The headset of the first, fourth, and sixth aspects of the invention may be the same headset.

0032An eighth aspect of the invention provides a computer readable storage device comprising software for configuring a headset to perform as described i relation to any of the first and seventh aspects described above.

0033Embodiments of the invention will now be described with reference to the accompanying drawings, in which:

0034Fig. 1 shows a schematic block diagram of a system including a headset according to a first embodiment of the invention;

0035Fig. 2 shows a flow diagram according to the first embodiment of the invention;

0036Figs. 3a to 3d show schematic diagrams of a cutting table and a wearer of a headset according to the first embodiment of the invention;

0037Fig. 4 shows a schematic diagram of a stacking table that is adjacent to the cutting table, along with the wearer of the headset according to the first

0038embodiment of the invention;

0039Fig. 5 shows a schematic diagram of a moulding table that is adjacent to the stacking table, along with the wearer of the headset according to the first embodiment of the invention;

0040Fig. 6 shows a schematic diagram of another cutting table and wearer of a headset according to a second embodiment of the invention;

0041Fig. 7 shows a schematic diagram of yet another cutting table and a wearer of a headset according to a third embodiment of the invention; and

0042Fig. 8 shows a schematic diagram of a room with yet another cutting table and a wearer of a headset according to a fourth embodiment of the invention. The figures are not to scale, and same or similar reference signs denote same or similar features

0043A first embodiment of the invention will now be described with reference to Figs 1 to 5. The schematic block diagram of Fig. 1 shows a system including a headset 20 that has a receiver REC connected to a processor PRC. The receiver REC receives data on fabric shapes that have been cut by a cutting device CNC. The data is received from a server SRV, which controls the cutting device CNC. The cutting device CNC in this embodiment is a knife cutting device for cutting through carbon fabric sheets.

0044The processor PRC instructs an optical device OPD to augment a wearer of the headset's field of view with various graphics. The optical device OPD may for example present the graphics by displaying an image on a display embedded within a lens of the headset, or by shining light directly into the eye of the wearer, as will be apparent to those skilled in the art.

0045The headset 20 further comprises a control interface INT, including a power on/off button, a small speaker, and control buttons. The interface INT is connected to the processor PRC. The processor PCR is also connected to a camera CAM, which records what the wearer of the headset is seeing within their field of field. The processor PRC analyses the video from the camera to look for relevant visual patterns/events. The headset 20 further comprises a set of accelerometers ACC, which are connected to the processor PRC and used to detect displacement of the headset from a known starting position, to calculate a current position. This can be used to help the headset determine whereabouts the field of view of the wearer lies. Optionally, the headset 20 also comprises a transponder device TPD that is connected to the processor PRC, and which may be used to receive signals from beacons within the nearby vicinity to help the headset 20 determine whereabouts the field of view of the wearer lies. The system optionally comprises a position controller PCNT for controlling a plurality of sensors S1 , S2, and S3 which may be used to sense the position of the headset within the room. For example, each one of the sensors S1 to S3 may detect the distance of the headset 20 from it, and send the distance to the position controller PCNT. The position controller PCNT compares the distances to determine the position of the headset 20, and sends this position to the processor PRC via the receiver REC. Again, this can help the headset 20 determine whereabouts the field of view of the wearer lies. The flow diagram of Fig. 2 will now be described in conjunction with Figs.

00463a to 5, to illustrate the use of the headset 20. In a first step 101 , a designer designs a nest of fabric shapes, by determining the fabric shapes that are needed to make particular composite product(s), and then fitting the determined fabric shapes into the area of a fabric sheet so as to minimize wastage of the fabric sheet. The designed nest of fabric shapes includes data specifying which product (mould) each fabric shape is intended for, and whereabouts the fabric shape should be placed relative to the other fabric shapes for the same mould.

0047In a second step 102, the designed nest of fabric shapes is sent from the server SRV to the cutting device CNC and the receiver REC of the headset 20. Then, in a third step 103, the cutting device CNC cuts a fabric sheet 62 to form the nest 60 (refer to Fig. 3a).

0048The schematic diagram of Fig. 3a shows a cutting table 30 and a person (wearer) 10 of a headset 20. The cutting table 30 has the fabric sheet 62 resting on top of the cutting table, and a plurality of fabric shapes 65 that together form the nest 60 cut by the cutting device CNC. The fabric shapes 65 are together referred to as a nest as they are all nested amongst one another. For illustrative purposes, in this embodiment the fabric shapes 65 are all triangular, although in practice the fabric shapes 65 would typically be a wide variety of different shapes to one another.

0049The cutting table 30 is within a room, and a wall of the room has a plaque 50 affixed to it. The plaque 50 bears a registration mark 55, as best seen in the enlarged view of Fig. 3b. The wearer 10 of the headset is shown looking towards the plaque 50 in Fig. 3a, and a boundary 40 designates a field of view of the wearer 10 when looking through the headset 20. The cutting table 30 is at a fixed position relative to the registration mark 55, and so the registration mark 55 informs the headset of its position relative to the cutting table 30, and therefore relative to the nest 60. In a step 104, the processor PRC recognizes the registration mark 55 within the video from the camera CAM, and determines the headset's current position in the room based on the

0050registration mark. Specifically, the direction the headset is pointing in is known from whereabouts the registration mark 55 appears in the field of view 40, and the position of the headset is known from how the registration mark 55 appears in the video, for example it will appear smaller the further away the headset is from the camera, and will appear in perspective if the headset is positioned to the left or the right of the registration mark 55.

0051Once the headset 20 has determined its position, it augments the wearer's field of view with a line 45, as seen in Fig. 3b. It also emits a bleep sound via a speaker of the interface INT, to inform the wearer that the registration mark 55 has been successfully detected and used by the headset to determine its position.

0052The line 45 has its origin at the centre of the field of view 40, and points downwardly towards the nest 60. The line 45 indicates to the wearer of the headset that he/she should look in the direction of the line 45 to find the first fabric shape that is to be picked up and moved to a stack.

0053As shown in Fig. 3c, the wearer 10 follows the line 45 by moving their head downwardly to bring the nest 60 of fabric shapes within their field of view 40. The headset 20 senses the movement of the headset using the accelerometers ACC embedded within the headset, and determines whereabouts the next fabric shape that is required to be selected will appear within the field of view 40, based on the movement detected by the accelerometers. Fig. 3d shows an enlarged view of the field of view 40 of Fig. 3c. It can be seen that the nest 60 has fabric shapes 65a to 65h that have been cut into the fabric sheet 62. Based on the designed nest of fabric shapes that was sent to the receiver REC, the processor PRC determines that the first fabric shape to be picked up and added to a stack is the fabric shape 65e.

0054In a step 105, the processor PRC instructs the optical device OPD to augment the wearer's field of view 40 by overlaying a graphic image 46 of the first fabric shape 65e, over the first fabric shape 65e. The graphic image 46 comprises hatched lines which appear on top of the first fabric shape 65e, although other types of image could alternatively be used. The line 45 points from the centre of the wearer's field of view 40 to the first fabric shape 65e.

0055The wearer then picks up the first fabric shape 65e from the next 60, and turns towards a stacking table that is positioned behind them. The headset 20 is programmed with the relative positions of the cutting table and the stacking table, and so is aware of when the wearer moves their field of view 40 over the stacking table, based on the accelerometers ACC. Fig. 4 shows a schematic view of the stacking table 34, and the wearer 10 looking at the top of the stacking table 34 within their field of view 40. The wearer 10 is shown holding the fabric shape 65e that has just been picked up from the cutting table 30. There are two stacks currently placed on stacking table 34, these are stacks 70 and 72. The stacks 70 and 72 each have a few fabric shapes in a stack, formed by fabric shapes cut from a previous fabric sheet.

0056The headset 20 is aware of which stack the fabric shape 65e should be added to, based on the designed nest of fabric shapes that was sent to it previously in step 102. In a step 106, the headset 20 augments the wearer's field of view 40 by overlaying the line 45 pointing from the centre of the field of view towards the stack 70 that the fabric shape 65e is to be added to. The image 46 of the fabric shape is also overlaid over the stack 70, to indicate where the fabric shape 65e should be added. The wearer 10 adds the fabric shape 65e to the stack 70, and then turns back to the cutting table 30 to pick up the second fabric shape, which is fabric shape 65h, as defined by the designed nest of fabric shapes that was sent to the headset in step 102.

0057The movement of the wearer 10 from the stacking table 34 to the cutting table 30 is detected by the accelerometers ACC, and this detection is interpreted as a notification that the wearer 10 has finished placed the fabric shape 65e onto the stack 70. Alternatively, it would be possible to define a specific head movement which the wearer could be trained to make once the fabric shape was placed on the stack, and which the accelerometers/processor could be configured to detect. Or, the processor could be configured to detect a specific hand gesture within the video recorded by the camera CAM, or could analyse the video to determine when the stack 70 had a new fabric shape added to it. Optionally, a button of the control interface INT could be pressed by the wearer to indicate to the headset that the wearer has placed the fabric shape 65e on the stack 70.

0058In the case where the processor analyses the video to determine when the stack 70 has a fabric shape added to it, the processor may sound an alarm via a speaker in the interface INT if the processor detects that the fabric shape has mistakenly been added to a stack other than the stack 70.

0059Once the wearer has turned back to the cutting table 30, the headset 20 highlights the second fabric shape 65h, in just the same manner as previously described for the first fabric shape 65e. Optionally, the wearer may be required to look at the registration mark 55 again to help re-calibrate the headset's

0060determination of its position within the room, and prevent small errors in position determination based on the accelerometers from compounding over time. The wearer picks up the second fabric shape, and transfers it to the stack

006172 of the stacking table 34 whilst being guided by the headset 20, in the same manner as described for the first fabric shape 65e. The wearer repeats the process again for fabric shapes 65a, 65b, 65g, 65d, 65c, 65f, so that all fabric shapes of the fabric sheet 62 have been transferred to the stacks 70 and 72. Accordingly, the stack 70 has fabric shapes 65e, 65a, 65g, 65c stacked in that order upon one another, and the stack 72 has fabric shapes 65h, 65b, 65d, 65f stacked in that order upon one another.

0062The stacks may be transferred to a moulding table, or may be stored away for use at the moulding table at a later time. The stack 70 provides one kit of fabric shapes in the order required to produce one composite product, and the stack 72 provide another kit of fabric shapes required to produce another composite product. Due to the headset 20, it was possible for the fabric shapes 65a - 65h to be all nested amongst one another in the nest 60, in the most area-efficient manner, without needing to position the fabric shapes destined for the stack 70 in a different part of the fabric sheet 62 from the fabric shapes destined for the stack 72.

0063The wearer 10 then moves a stack of fabric shapes 75 to a moulding table 36, shown in Fig. 5. The stack of fabric shapes 75 was created previously, and constitute a kit for use with the mould 80 placed on top the table 36. The stack of fabric shapes 75 is a different stack to the stacks 70 and 72, although in an alternate embodiment the stacks 70 or 72 are immediately used with an

0064associated mould, rather than the stack 75 and mould 80.

0065The stack 75 comprises multiple fabric shapes, which are to be placed one- by-one into various positions within the mould 80 to form a composite product. The headset 20 is informed by the server SRV that the stack 75 is to be added to the mould 80, by sending data on the stack 75 to the receiver REC of the headset 20. The data on the stack 75 that is sent to the headset 20 includes data on each fabric shape within the stack 75, and whereabouts each fabric shape needs to be added to the mould 80 to form the composite product. The fabric shapes are added to the mould 80 in reverse order to the order that they were originally added to the stack 75. For example, the fabric shape 67 at the top of the stack was the last fabric shape to be added to the stack 75, but will be the first fabric shape to be added to the mould 80. The headset 20 recognises that the stack 75 and the mould 80 are within its field of view 40, by the processor PRC analyzing video from the camera CAM. Alternatively, a registration mark may be used so that the headset can determine its position, in the same manner as described previously for the registration mark 55.

0066In a step 1 1 1 , the processor PRC instructs the optical device OPD to overlay an image 49 of the fabric shape 67 that is on top of the stack 75. The image 49 is overlaid over the mould 80, and the image has the same size, shape, and position as how the fabric shape 67 will appear once it has been correctly added to the mould 80.

0067In this embodiment, the headset also overlays two fold lines 47 and 48 onto the stack 75 within the wearer's field of view 40, the fold lines indicting to the wearer of the headset two folds that need to be made to the fabric shape 67 for the fabric shape 67 to be correctly fitted into the mould 80.

0068The wearer picks up the fabric shape 67, and places it into the mould 80, in the position indicated by the image 49. In a step 1 12, the wearer 10 notifies the headset 20 that the fabric shape 67 has been placed into the mould, by making a specific hand gesture in front of the camera CAM of the headset. The processor PRC recognises the hand gesture within the video, and in response in a step 1 13 overlays an image of the next to last fabric shape of the stack 75, at a position within the mould 80 showing how the next to last fabric shape should be fitted into the mould 80.

0069As an alternative to using a hand gesture, the headset may detect from the video recorded by the camera CAM that the last fabric shape 67 has been placed into the mould 80, and in response overlay the image of the next to last fabric shape in the mould 80. In that case, the speaker of the interface INT may sound a warning if the processor PRC detects that the fabric shape has been placed in an incorrect position within the mould. Once the next to last fabric shape has been placed in the mould 80, and this has been notified to the processor PRC in a step 1 14, an image of the next fabric shape at the top of the stack 75 is overlaid on the mould 80, and the fabric shape is placed therein, and so on until all the fabric shapes of the stack 75 have been placed into the mould 80. The fabric shapes are then baked at high temperature to form the composite product, along with a resin if the fabric shapes were not pre-impregnated with resin.

0070Clearly, if more than one stack and more than one mould are present on the moulding table 36, then the headset may be used to highlight which stack the next fabric shape to be picked up is at the top of, and which mould the next fabric shape is to be placed in. The stack that the next fabric shape is to be picked up from may be highlighted in response to the notification that the previous fabric shape has been placed in the corresponding mould.

0071The schematic diagram of Fig. 6 illustrates a second embodiment of the invention, which is the same as the first embodiment, except for that the cutting table 30a has a registration mark 55a embedded in the cutting table. Then, there is no need for the headset to be aware of a positional relationship between the plaque 50 (see Fig. 3a) and the cutting table. In this embodiment, the line 45a is overlaid within the wearer's field of view 40 to extend from the wearer towards the registration mark 55a, so the wearer is informed that the headset 20 has

0072recognised the registration mark 55a. The schematic diagram of Fig. 7 shows a third embodiment of the invention, which is the same as the first embodiment, except for that instead of registration mark 55 being used to determine the position of the headset relative to the nest 60, the nest, now referred to as nest 60a, is provided with registration marks 68 around its periphery. The registration marks are not evenly distributed, so that the camera CAM and processor PRC of the headset 20 can determine the position of the headset relative to the nest 60a. Then, there is no need for the headset to be aware of a positional relationship between the cutting table and the nest 60a. In this embodiment, the line 45a is overlaid within the wearer's field of view 40 to extend from the wearer towards the next fabric shape 65ea to be picked up from the cutting table. An image 46 of the fabric shape is overlaid over the fabric shape 65ea by the registration mark 55a, so the wearer is informed that the headset 20 has recognised the registration mark 55a.

0073The registration marks 68 are printed onto the fabric sheet 62, and may for example be white coloured circles. The registration marks 68 can be printed in the same place on every fabric sheet 62, regardless of the fabric shapes to be cut into the fabric sheet.

0074The schematic diagram of Fig. 8 shows a fourth embodiment of the invention, which is the same as the first embodiment, except for that instead of registration mark 55 being used to determine the position of the headset relative to the nest 60, beacons B1 - B3 are placed around the room in which the cutting table is present. The beacons B1 to B3 are radio frequency transmitters which each transmit with a fixed signal strength. The headset 20a comprises the optional transponder TPD (also see Fig. 2) connected to the processor PRC, and receives the signals from the beacons B1 - B3. Based on the received signal strengths, and the known locations of the beacons B1 - B3, the processor PRC determines the location of the headset relative to the cutting table and the net 60.

0075The transponder TPD comprises three separate antennas spaced apart from one another, each of whose locations are determined, so that the direction in which the headset is facing can also be determined.

0076Based on the detected position and direction, the headset 20 augments the wearer's field of view 40 with an image 46 of the first fabric shape 65e, over the first fabric shape. A line 45a pointing from the headset to the first fabric shape is also overlaid by the headset into the wearer's field of view 40.

0077In a fifth embodiment of the invention, the position of the wearer's field of view 40 is determined by implementing the positional controller PCNT and sensors S1 - S3, as described earlier with reference to Fig. 2. The sensors S1 - S3 may be located in similar positions to the beacons B1 - B3 of Fig. 8.

0078Various combinations of the methods for detecting where the field of view 40 of the headset lies may be combined to increase the accuracy of the position determination, for example the beacons B1 - B3 and transponder may be used to determine the rough position and direction of the headset, and registration mark(s) and/or analysis of the video from the camera CAM may be used to refine the rough position and direction detected by the transponder.

0079In a further embodiment, the processor PRC instructs the optical device OPD to overlay images over more than one of the fabric shapes on the cutting table at a time, the images indicating a sequence in which the fabric shapes are to be picked up. For example, with reference to Fig. 3a, the fabric shape 65h may have an image of itself overlaid over it by the optical device OPD, the image having a different cross-hatching style to that of the image 46, the different cross- hatching style indicating to the wearer that the fabric shape 65h is to be picked up after the fabric shape 65e is picked up. Then, when the wearer moves to the stacking table 34, the wearer will place the fabric shape 65h on the stack 72 indicated first by the headset, and the fabric shape 65e on the stack 70 indicated second by the headset. The wearer may perform a hand gesture once the fabric shape 65e has been placed on the stack 70, to notify the headset that the next fabric shapes 65a and 65b are to be picked up. Further alternate embodiments falling within the scope of the appended claims will also be apparent to the skilled person.