BACKGROUND

The invention relates to a method, a system and a computer program product for detecting irregularities in one or more tire components on a tire building drum.

Tire components , in particular tire layers of uncured rubber, are wound around a tire building drum to a form a green or unvulcanized tire . The trailing end of each ply is spliced to the leading end of the same ply . The quality of each splice, the centering of the layers and the uniformity of the material may be of considerable influence on the overall quality of the tire . It is known to have a human operator visually inspect the splices of each green tire for defects or irregularities , such an open splice . Based on the visual inspection - and experience - the human operator decides to approve or rej ect the green tire .

SUMMARY OF THE INVENTION

A disadvantage of the known visual inspection is that the human operator has to inspect each splice in its entirety . The detection and/or assessment of irregularities in the one or more tire plies is therefore limited to what can be seen with the naked eye, subj ective and prone to human error .

It is an obj ect of the present invention to provide a method, system and computer program product for detecting irregularities in one or more tire components on a tire building drum, wherein the detection and/or assessment of the irregularities can be improved .

According to a first aspect , the invention provides a method for detecting irregularities in one or more tire components on a tire building drum, wherein the method comprises the steps of : obtaining scans of the one or more tire components on the tire building drum at a plurality of angular positions of said tire building drum about a drum axis ; creating a virtual representation of the one or more components based on the scans ; and reorienting one of the virtual representation and the tire building drum in response to a change in orientation of the other of the virtual representation and the tire building drum .

The reorientation ensures that the human operator can easily relate a virtual positions of any areas of interest in the virtual representation to the corresponding real world positions at the tire building drum. In other words : a human operator can use the virtual representation to analyze and determine any irregularities in the virtual representation and to locate said irregularities in the real world on the tire building drum. The human operator can therefore focus the attention to specific areas of the one or more tire components on the tire building drum based on areas of interest in the virtual representation, instead of focusing on the one or more tire components as a whole . In this manner, the detection and/or assessment of the irregularities can be improved and the chance of human error can be reduced considerably .

In one embodiment the creation of the virtual representation based on the scans is completed prior to the reorienting . In another embodiment the obtaining of scans is completed prior to the reorienting . In other words , the scanning and creation of the virtual representation can be part of a preparation mode in which the information for the virtual representation is collected and the virtual representation is created . The preparation mode can be carried out automatically . When said preparation mode has been completed, a switch can be made to an operational mode or a manual mode in which the orientations of the virtual representation and the tire building drum can be adj usted in response to each other 'as is ' , i . e . based on the state of the tire building drum, the one or more tire components and the virtual representation thereof without requiring new or further scans and/or without recreation of the virtual representation from said scan . In particular, actions of the human operator to correct irregularities in the one or more tire components are not reflected in real-time in the virtual representation, but can be scanned again in a subsequent cycle of the method . Hence, the human operator can assess the irregularities in the virtual representation based on the state of one or more tire components on the tire building drum at the end of the preparation mode .

In one embodiment the virtual representation is three dimensional . The virtual representation is three- dimensional in the sense that represents the one or more components in three dimensions : width, height and depth . The virtual representation is still to be considered three dimensional even when it is shown on a two dimensional visual user interface , such as a display .

In another embodiment the virtual representation extends about a virtual axis representing the drum axis . Hence, the human operator can visually relate the virtual axis to the drum axis in the real world, and vice versa .

Preferably, the step of reorienting involves rotating one of the virtual representation and the tire building drum about the virtual axis and the drum axis , respectively, in response to a change in angular position of the other of the virtual representation and the tire building drum about the virtual axis and the drum axis , respectively . The human operator can visually relate the virtual rotation to the rotation of the tire building drum in the real world, and/or vice versa .

More preferably, the method further comprises the steps of : linking a plurality of virtual angular positions of the virtual representation about the virtual axis to a plurality of real world angular positions of the tire building drum about the drum axis ; and rotating the virtual representation and the tire building drum to a linked pair of the virtual angular positions and the real world angular positions . The linked pairs can ensure that the virtual representation is in the same virtual angular position for each real world angular position of the tire building drum. In particular, the linked pairs may be chosen such that , from the viewpoint of the human operator, the side of the virtual representation that faces the human operator at any moment in time corresponds to the side of the tire building drum facing the human operator at the same moment in time .

In a further embodiment the virtual representation and the tire building drum are rotated in the same direction and/or at the same speed . Hence, the human operator can relate the motion of the virtual representation to the motion of the tire building drum in the real world, and vice versa .

In another embodiment the method further comprises the steps of : using an inspection reference , in particular a proj ection, more in particular a laser proj ection, to indicate a real world reference position relative to the one or more tire components ; and adding a virtual reference to the virtual representation in a virtual reference position corresponding to the real world reference position indicated by the inspection reference . The human operator can relate the inspection reference to the virtual reference, and vice versa, for more easily locating any areas of interest with respect to said references .

Preferably, the real world reference position is fixed . Hence , the human operator can trust the real world reference position to always be in the same place .

In another embodiment the method further comprises the steps of : analyzing the scans and recognizing one or more irregularities in said scans ; and indicating the one or more irregularities in the virtual representation . By indicating the one or more irregularities in the virtual representation, the human operator can relate the virtual positions of those one or more irregularities to corresponding real world positions on the tire building drum. The human operator can focus on these real world positions instead of inspecting the one or more tire components as a whole .

In another embodiment the change in orientation of the other of the virtual representation and the tire building drum is controlled by a human operator . Hence, the operator himsel f or herself can change the orientation of the virtual representation or the tire building drum such that a side that has an area of interest faces the human operator .

Alternatively, the change in orientation of the other of the virtual representation and the tire building drum is controlled automatically to show one or more irregularities . In this way, the virtual representation or the tire building drum can be brought into the best orientation for inspecting an identi fied irregularity . When there are more than one irregularities , the orientation may be changed in steps , allowing some time for inspection between each step, or awaiting user confirmation before continuing with the next step .

In another embodiment the virtual representation is displayed to a human operator on an electronic visual display . The electronic visual display can be place in a position near the tire building drum in which the human operator, from a dedicated viewpoint, can easily observe both the virtual representation and the tire building drum and relate information and/or positions between them . Alternatively, the virtual representation is displayed to a human operator at a real world position of the tire building drum as part of an augmented reality or mixed reality . The virtual representation can thus be presented to the human operator as an overlay in a direct relationship with the real world, thus making it easier for the human operator to relate the information and/or positions shown in the virtual representation to the real world .

In another embodiment the method further comprises the step of : correcting the virtual representation taking into account a parameter indicative of a viewing angle of a human operator to the drum axis . For example, when a human operator has a downward view angle to the drum axis , the orientation of the virtual representation can be corrected or offset to take into account said downward view angle, such that the virtual representation better matches the view that the human operator has of the tire building drum .

Preferably, the parameter is entered by the human operator . The human operator may therefore enter, adj ust or override a previously entered parameter to check by trial and error if the corrected orientation of the virtual representation corresponds to the view of the human operator on the tire building drum.

In a further embodiment the parameter is one of the group comprising : eye level , human height and viewing angle . This kind of parameter can be used to predict or calculate how or by which amount the virtual representation should be corrected to take into account the speci fic parameter .

In another embodiment the scans comprise height profile information of the one or more tire components on the tire building drum . The height profile information can be used to create an accurate virtual representation of the outer surface of the one or more tire components on the tire building drum.

In another embodiment a virtual model of the tire building drum is added to the virtual representation . Hence, the one or more tire components do not appear to be floating in the air . Instead, they can be displayed as if they are supported on the virtual model of the tire building drum to make the virtual representation more realistic and/or more relatable to the real world .

In another embodiment the scans are obtained by rotating the tire building drum about the drum axis relative to one or more scanners . The tire building drum is already rotated as part of the tire building operation . Hence, to obtain the scans , the tire building drum can simply be rotated over at least one revolution . The scanning equipment, for example one or more cameras , can be arranged in a reliable manner in a fixed position relative to the fixed world . Alternatively, in a less reliable solution, the tire building drum may be kept stationary and the scanning equipment may be moved around the tire building drum .

Preferably, the tire building drum is rotated over a full revolution during the obtaining of the scans . Hence, the scans of the one or more tire components can be obtained along the entire circumference of the tire building drum, thus facilitating the creation of a virtual representation that spans the entire circumference .

According to a second aspect , the invention provides a system for detecting irregularities in one or more tire components on a tire building drum, wherein the system comprises one or more scanners for scanning the one or more tire components on the tire building drum, a visual user interface and a control unit that is operationally connected to the one or more scanners and the visual user interface, wherein the control unit is configured for : obtaining scans of the one or more tire components on the tire building drum at a plurality of angular positions of said tire building drum about a drum axis ; creating a virtual representation of the one or more tire components based on the scans and displaying said virtual representation to a human operator via the visual user interface ; and reorienting one of the virtual representation and the tire building drum in response to a change in orientation of the other of the virtual representation and the tire building drum .

The system according to the second aspect of the invention is used to practically implement the method according to the first aspect of the invention and thus has the same technical advantages , which will not be repeated hereafter . Moreover, the system can be used to implement any one of the aforementioned embodiments of the method according to the first aspect of the invention, in particular, but not limited to :

A first embodiment in which the system further comprises an electronic visual display, wherein the visual user interface is configured to be displayed on the electronic visual display .

A second embodiment in which the system further comprises an augmented reality device, wherein the visual user interface is configured for displaying the virtual representation at a real world position of the tire building drum as part of an augmented reality or mixed reality via the augmented reality device .

According to the third aspect, the invention provides a computer program product comprising a non- transitory computer-readable medium holding instructions that, when executed by a processor, cause a system according to any one of the embodiments according to the second aspect of the invention to perform the steps of the method according to the first aspect of the invention .

The computer program product can be provided separately from the system to configure, upgrade and/or install the aforementioned functionality in said system, resulting in the previously discussed technical advantages .

According to a fourth aspect, the invention provides a method for detecting irregularities in one or more tire components on a tire building drum, wherein the method comprises the steps of : obtaining scans of the one or more tire components on the tire building drum at a plurality of angular positions of said tire building drum about a drum axis ; creating a virtual representation of the one or more components based on the scans ; overlaying one or more virtual boundaries on the virtual representation representative of one or more tolerance ranges for the one or more tire components ; and providing markings in the virtual representation where , based on the scans , the one or more tire components are out of a first tolerance range of the one or more tolerance ranges .

The method according to the fourth aspect of the invention may be applied in combination with any of the embodiments of the method according to the first aspect of the invention, or independently thereof .

Although it is known to provide markings indicating irregularities , the markings themselves do not provide useful information to accurately assess the reasons for the irregularity, for example an exceedance of a tolerance range, and the severity thereof . The marking also do not provide any information on how to fix the irregularity, for example in which direction the one or more tire components should be repositioned to be within the relevant tolerance range .

The method according to the fourth aspect of the invention has the technical advantage that, in addition to marking the virtual representation where the one or more tire components are out of tolerance, the same virtual representation also shows the reason why said one or more tire components are out of tolerance by visualizing the relevant tolerance range with the visual boundaries . Hence , the human operator can more accurately assess the reason for the marking, as well as the severity of the tolerance exceedance relative to the one or more virtual boundaries . The visualization of the tolerance ranges with the use of the visual boundaries may aid the human operator in determining the best way to fix the irregularity, e . g . by determining the direction in which the tire components should be repositioned to be within the relevant tolerance range . A human operator may also, based on experience, ignore a tolerance exceedance when it is only marginal and/or when the traj ectory of the contour is mainly within the relevant tolerance range and out of the virtual boundary only very locally .

In a preferred embodiment the one or more virtual boundaries comprise a first boundary line and a second boundary line parallel to and spaced apart from the first boundary line, representative of a lower limit and an upper limit, respectively, of the first tolerance range . By visualizing the lower limit and the upper limit of the first tolerance range , the human operator can understand why a part of the tire components extending outside of the area between the lower limit and the upper limit is marked as being out of tolerance .

In a further embodiment the one or more virtual boundaries comprise a third boundary line and a fourth boundary line extending perpendicular to the first boundary line and the second boundary line to form a boundary box . By providing a boundary box, the box-shaped area between the boundary lines can be visually ascertained more easily .

Preferably, the third boundary line and the second boundary line are representative of a lower limit and an upper limit, respectively, of a second tolerance range of the one or more tolerance ranges . Hence , the boundary box can visualize two tolerance ranges at once , i . e . two tolerance ranges in two orthogonal directions . For example, the boundary box may visualize a height tolerance range between the first boundary line and the second boundary line while visualizing a width tolerance range between the third boundary line and the fourth boundary line .

In another embodiment the one or more virtual boundaries define a box-shaped area, wherein said box-shaped area is provided with a pattern or a transparent fill . Hence , the box-shaped area can be visually ascertained more easily while also keeping the underlying features of the one or more tire components visible .

In another embodiment the one or more tolerance ranges apply to one or more contours of the one or more tire components , wherein the markings highlight where the one or more contours of the one or more tire components are out of the one or more tolerance ranges . Hence, it can be visually determined why some parts of the contours are marked as being out of the first tolerance range .

Preferably, the markings are traced parts of the contours of the one or more tire components . Hence , it can be accurately visualized which parts of the contours are out of the first tolerance range .

In another embodiment the virtual representation comprises a two-dimensional view, wherein the one or more virtual boundaries are overlayed on the virtual representation in said two-dimensional view . In the two- dimensional view, the relationship between the markings and the visual boundaries can be determined more easily .

Preferably, the virtual representation comprises a three-dimensional view related to the two-dimensional view, wherein the one or more virtual boundaries , the markings or both are provided simultaneously in the three-dimensional view and the two-dimensional view . The simultaneous visualization in both the two-dimensional view and the three- dimensional view allows the human operator to correlate the markings and/or virtual boundaries in one of the two views with the markings and/or virtual boundaries in the other of the two views .

The various aspects and features described and shown in the specification can be applied, individually, wherever possible . These individual aspects , in particular the aspects and features described in the attached dependent claims , can be made subj ect of divisional patent applications . BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be elucidated on the basis of an exemplary embodiment shown in the attached schematic drawings , in which : figure 1 shows a perspective view of a tire building drum with one or more tire components and system for detecting irregularities in said one or tire components , according to a first exemplary embodiment of the invention; figure 2 shows a perspective view of the tire building drum and the system according to figure 1 , after the tire building drum has been rotated to a di fferent angular position; figure 3 shows a flow chart of the steps of a method for detecting irregularities in the one or more tire components on the tire building drum, using the system according to figures 1 and 2 ; figure 4 shows a perspective view of the tire building drum of figure 1 and an alternative system according to a second exemplary embodiment of the invention; figure 5 shows a perspective view of the tire building drum of figure 1 and a further alternative system according to a third exemplary embodiment of the invention; and figure 6 shows a screen of an alternative visual user interface for identifying irregularities in one or more tire components on the tire building drum of figure 1 , according to a fourth exemplary embodiment of the invention .

DETAILED DESCRIPTION OF THE INVENTION

Figures 1 and 2 show a system 1 according to a first exemplary embodiment of the invention for detecting irregularities X in one or more tire components T on a tire building drum D . The tire building drum D may be any drum or wheel used in a tire manufacturing process to receive , build, shape and/or trans fer one or more tire components T . The one or more tire components T are used to build a green or unvulcanized tire . The one or more tire components T may comprise layers , plies , strips or the like , for example an inner-liner, a side wall , a breaker, a tread, a cap strip, a gum strip, or a combination thereof .

The tire building drum D comprises a cylindrical support surface that is rotatable about a drum axis Al . The system 1 comprises a drive 2 for driving the rotation of the tire building drum D about the drum axis Al . During the application of the one or more tire components T on the tire building drum D, the rotation of the tire building drum D about the drum axis Al is controlled automatically . The system 1 may however also comprise a manual control 3 for manual control of the rotation of the tire building drum D about the drum axis Al by a human operator H, for example for inspection purposes or maintenance .

The one or more tire components T are applied to said cylindrical support surface by winding pre-formed layers of said one or more tire components T onto the tire building drum D or by may be applied in the form of a continuous strip using an additive process like strip-winding . The one or more tire components T may form a so-called 'package ' or 'assembly' on the tire building drum D . In particular, the one or more tire components T may form a 'pre-assembly' of an inner- liner, a body ply and/or side walls or a 'package ' of a belt and a tread .

The one or more tire components T typically comprise one or more splices S where a leading end of one ply is j oined, stitched or spliced to a trailing end of the same or another ply . The splices S may be formed by overlapping ends of the one or more tire components T, a so-called 'overlapping splice' , or by butt-j oining the ends of the one or more tire components T, a so-called 'butt splice' . A common fault when splicing is that the ends of the one or more tire components T are not fully j oined along the splice S , a so- called 'open splice ' , or that the ends overlap when forming a 'butt splice' . It is known to manually inspect the splices S for such faults .

The system 1 as shown in figure 1 comprises one or more imaging devices or scanners 4 for obtaining height profile data, images , scans of the one or more tire components T on the tire building drum D . In this example , each scanner 4 comprise an optical camera with a field of view that is directed at or covers at least a part of the tire building drum D . The optical camera may cooperate with a laser to obtain height profile information of the one or more tire components T along a laser line . In this particular case, the system 1 comprises a plurality of scanners 4 arranged side- by-side, each with its own field of vision, together covering the entire width of the tire building drum D, or at least the width of the area covered by the one or more tire components T . Alternatively, a line-scan camera may be used to observe a single line of pixels at a time .

In this example, the one or more scanners 4 are in a stationary position relative to the fixed world . In other words , the tire building drum D is rotatable about the drum axis Al relative to the one or more scanners 4 . Alternatively, the tire building drum D may be held stationary relative to the fixed world and the one or more scanners 4 may be movable around said stationary tire building drum D .

The system 1 further comprises one or more proj ectors 5 for proj ecting one or more real world references R1 onto the tire building drum D and/or the one or more tire components T at a real world reference position . In this example, the real world reference position is in a fixed position relative to the fixed world and/or the drum axis Al . In other words , the tire building drum D is rotatable about the drum axis Al relative to the one or more real world references R1 which remains in a fixed angular position .

The system 1 is further provided with an electronic visual display 60 , e . g . a television screen, for displaying a visual user interface 6 to the human operator H .

The system 1 further comprises a control unit 7 that is electronically, functionally and/or operationally connected to the drum drive 2 , the manual control 3 , the one or more scanners 4 , the proj ectors 5 and the electronic visual display 60 . The control unit 7 comprises a processor and a memory, in particular a non-transitory computer-readable medium, for holding instructions that, when executed by the processor, cause the system 1 to operate in a manner as described in more detail hereafter .

As shown in figure 1 , the system 1 is further provided with an encoder 8 , in particular a rotary encoder, for detecting and generating a signal indicative of the angular position of the tire building drum D .

A method for detecting irregularities X in the one or more tire components T on the tire building drum D using the aforementioned system 1 will now be elucidated with reference to figures 1 , 2 and 3 .

As shown in the flow chart of figure 3 , the method starts with generating a relative rotation between the tire building drum D and the one or more scanners 4 about the drum axis Al , in particular by rotating the tire building drum D about said drum axis Al ( step S I ) , while the one or more scanners 4 obtain scans of the one or more components T on the tire building drum D at a plurality of angular positions Pl of said tire building drum D about said drum axis Al ( step S2 ) . The scans are preferably obtained during a full or complete revolution of the tire building drum D about the drum axis Al , e . g . over a rotation of at least three-hundred- and-sixty degrees . Alternatively, the scans may be limited to a speci fic range of the circumference of the tire building drum D, which may be less than a full revolution . Each scan is stored in the memory or a database and linked to the angular position Pl of the tire building drum D at which the respective scan was taken based on the signals received from the encoder 8 in figure 1 ( step S3 ) .

The control unit 7 is arranged, programmed and/or configured for processing the scans and creating a virtual representation V of the one or more components T based on said scans ( step S4 ) . The control unit 7 may further be arranged, programmed and/or configured to add a virtual model M of the tire building drum D to the virtual representation V at a position relative to the virtual representation of the one or more tire components T corresponding to the real world position of the tire building drum D relative to the one or more tire components T .

In this example, the virtual representation V is or appears to be three dimensional . In particular, the virtual representation V extends about a virtual axis A2 representing the drum axis Al . More in particular, the virtual representation V is virtually rotatable about the virtual axis A2 . Each virtual angular position P2 of the virtual representation V about the virtual axis A2 is linked to a respective real world angular positions Pl of the tire building drum D about the drum axis Al , as shown in the table L in figure 3 .

In this example, the virtual angular position P2 is of fset with respect to the real world angular position, as detected by the encoder 8 , with a parameter K, as shown schematically as a delta symbol in figure 3 , indicative of a viewing angle B of the human operator H, as shown in figure 1 . The parameter K can be used to correct the orientation of the virtual representation V such that the virtual representation V better matches the view that the human operator H has of the tire building drum D . Typically, the viewing angle B is somewhere between forty and sixty degrees , depending on the human height, and in particular the eye level , of the human operator H . Because the offset parameter H may be di fferent for each human operator H and may be subj ect to user preference , it can be entered or adj usted manually by the human operator H . In the table L of figure 3 , all values of the virtual angular positions P2 are offset by the parameter K with a value of forty- five degrees with respect to the real world angular positions Pl .

Alternatively, the coordinate system of the virtual representation V can be offset with respect to the coordinate system of the tire building drum D with the same parameter K, in which case the values of the real world angular positions Pl and the virtual angular positions P2 can be kept the same .

The control unit 7 is further arranged, programmed and/or configured for analyzing the scans and recognizing one or more irregularities X in said scans ( step S5 ) . Virtual pointers , markers or indicators are added to the virtual representation V at virtual locations , as shown schematically with a square marker in figure 2 , corresponding to the real world locations of the respective irregularities X in the one or more tire components T . The marker may generally indicate an area of interest, or it may speci fically highlight or trace the contour of an irregularity X or even precisely pinpoint the location of the irregularity X .

In this example, steps S I to S5 can be part of a preparation mode which is to be completed prior to continuing to the next step of the method . Steps S I to S5 may be performed automatically . The control unit 7 is configured for switching between the preparation mode and a manual mode or operational mode . In the operational mode , the human operator H has manual control over the virtual representation V and/or the tire building drum D .

In the operational mode , the virtual representation V, including the marked irregularities X, is sent to the electronic visual display 60 to be displayed via a visual user interface 6 to the human operator H ( step S 6 ) . The virtual representation V is shown such that, from the viewpoint of the human operator H, the side of the virtual representation V that faces the human operator H corresponds to the side of the tire building drum D currently facing the human operator H .

While the virtual representation V is being displayed to the human operator H, the control unit 7 is further arranged, configured and/or programmed to monitor the angular orientation of one of the tire building drum D and the virtual representation V ( step S7 ) . The control unit 7 continuously monitors if the angular orientation has changed ( step S8 ) . The "N" loop is active when no change in orientation is detected .

When a change in orientation is detected the control unit 7 continues to the next step, as shown with arrow "Y" . In this next step the control unit 7 is arranged, configured and/or programmed to obtain the angular position Pl , P2 linked to the new angular position Pl , P2 of said one of the tire building drum D and the virtual representation V in the table L ( step S 9 ) .

In the final step ( step S10 ) the control unit 7 is arranged, programmed and/or configured for reorienting one of the virtual representation V and the tire building drum D in response to the change in orientation of the other of the virtual representation V and the tire building drum D to the linked angular position Pl , P2 . The virtual representation V and the tire building drum D are rotated in the same direction and/or at the same speed . Consequently, the human operator H can relate the motion of the virtual representation V to the motion of the tire building drum D in the real world, and vice versa . More in particular, steps S7 , S 8 , S9 and S10 are performed so quickly that the movements of the virtual representation V and the tire building drum D appear to be simultaneous or synced .

In this example, the rotation of the tire building drum D is controlled by the human operator H via the manual control 3 and the virtual representation V is configured to passively follow changes in the angular orientation of the tire building drum D . The updated virtual representation V is send to and displayed via the visual user interface 60 . Alternatively or alternatively, the human operator H may be able to change the angular orientation of the virtual representation V, for example via controls in the visual user interface 6 , in which case the tire building drum D may be controlled to passively follow changes in the angular orientation of the virtual representation V .

Alternatively, the control unit 7 is arranged, programmed and/or configured to control the orientation of the virtual representation V and/or the tire building drum D automatically to show one or more irregularities X . In this way, the virtual representation V and/or the tire building drum D can be brought into the best orientation for inspecting an identified irregularity X . When there are more than one irregularities X, the orientation may be changed in steps , allowing some time for inspection between each step, or awaiting user confirmation before continuing with the next step .

During the aforementioned steps of the method, the one or more proj ectors 5 are controlled to proj ect the one or more real world references R1 onto the tire building drum D and/or the one or more tire components T at the real world reference position, as shown in figures 1 and 2 . The control unit 7 is further arranged, programmed and/or configured for adding one or more virtual references R2 to the virtual representation V in a virtual reference position corresponding to the real world reference position indicated by the one or more inspection references R1 . In this example , the one or more real world references R1 are formed by two triangular pointers which are proj ected onto the tire building drum D in the same angular position on opposite sides of the one or more tire components T . The virtual references R2 have a similar shape to the real world references R1 and can thus be easily related to said real world references R1 .

The one or more real world references R1 indicate a line or an area on the tire building drum D that corresponds to the line or the area indicated by the one or more virtual references R2 in the virtual representation V, and vi ce versa . In particular, the angular positions Pl , P2 of the one or more real world references R1 and the one or more virtual references R2 are linked in the table K in figure 3 .

To further aid the human operator H in understanding the relationship between angular positions Pl , P2 of the virtual representation V and the tire building drum D, the control unit 7 may be further arranged, programmed and/or configured to add an orientation view C to the visual user interface 6 , as shown in figures 1 and 2 . The orientation view C may acts as a compass showing the angular position Pl , P2 of the virtual representation V and/or the tire building drum D that is currently facing the human operator H . The orientation view C may further show the aforementioned virtual reference R2 at said current angular position Pl , P2 .

Figure 4 shows an alternative system 101 according to a second exemplary embodiment of the invention, which dif fers from the aforementioned system 1 in that the virtual representation V is shown to the human operator H via a mixed reality device or an augmented reality device 160 that is capable of displaying the virtual representation V at the real world position of the tire building drum D as part of a mixed reality or augmented reality AR . In this particular example, the augmented reality device 160 is a wearable device comprising augmented reality glasses 161 through which the human operator H can observe the real world tire building drum D at any viewing angle . The augmented reality device 160 is electronically, functionally and/or operationally connected to the control unit 7 , preferably via a wireless connection W, to receive the virtual representation V, which is constantly updated by the control unit 7 and/or the augmented reality device 160 to match the current viewing angle of the human operator H relative to the tire building drum D . The virtual representation V is shown to the human operator H via the augmented reality glasses 161 , as part of a visual user interface 106 overlaying the tire building drum D .

Figure 5 shows a further alternative system 201 according to a third exemplary embodiment of the invention, which dif fers from the alternative system 101 of figure 4 in that the mixed reality device or the augmented reality device 260 is a handheld device, for example a tablet or a smartphone, with a screen 261 and a camera 262 for filming the tire building drum D from any viewing angle . The tire building drum D as filmed by the camera 262 is shown in real- time via a visual user interface 206 on the screen 261 . Like the aforementioned augmented reality device 160 , the augmented reality device 260 of figure 5 is connected to the control unit 7 to receive the virtual representation V, which is constantly updated by the control unit 7 and/or the augmented reality device 260 to match the current viewing angle of camera 262 relative to the tire building drum D . The virtual representation V is added to the visual user interface 206 on the screen 261 .

Figure 6 shows an alternative visual user interface 306 for identifying irregularities X in the one or more tire components T on the tire building drum D of figure 1 . The alternative visual user interface 306 di ffers from the aforementioned visual user interfaces 6, 106 , 206 in that it has several views , including a three-dimensional view V0 and five two-dimensional views V1-V5 .

Each view V0-V5 shows a virtual representation V of the one or more tire components T based on the scans obtained in the manner as described before . In the three- dimensional view V0 , irregularities X are identified, using appropriate pointer, indicators or markers Zl , Z2 . The markers Zl , Z2 may generally indicate an area of interest, or they may speci fically highlight or trace the contour of an irregularity X or even precisely pinpoint the location of the irregularity X . In this example , the irregularity X is detected on a part of the splice S and said part is provided with a first marking Z l , for example a trace of the relevant contour that is the cause of the irregularity X . Another irregularity is detected in the lateral position of one of the beads , as highlighted with a second marker Z2 . Note that in figure 6, the first marking Zl is shown as a thicker line portion of the splice S . Alternatively, the first marking Zl may have the same line thickness as the splice S , while having a different color .

The five two-dimensional views V1-V5 comprise a first two-dimensional view VI showing a first contour G1 of the splice S in more detail . In particular, the first two- dimensional view VI is taken along the width of the splice S and shows a height profile of said splice S in a direction perpendicular to the axis of the tire building drum D . From said first contour Gl , a shape , height and/or width of the splice S can be derived .

In the first two-dimensional view VI , the same first marker Z1 is provided as in the three-dimensional view VO to highlight the irregularity X in a position corresponding to the position of the marker Z in the three-dimensional view VO . In addition, the first two-dimensional view VI includes one or more virtual boundaries R1-R5 , shown in dashed lines , which are added to , superimposed over or overlayed on the virtual representation V . The virtual boundaries R1-R5 are representative of one or more tolerance ranges for the one or more tire components T . In this example , the tolerance ranges are speci fically related to the design specifications of the splice S . More specifically, in this example, the splice S is divided into several areas , each having its own tolerance range, as reflected by the dif ferent virtual boundaries R1-R5 . The areas may be shown as distinct areas , or they may be alternatively combined into a single area .

The other two-dimensional views V2-V5 are cylinder proj ections of the one or more tire components T taken in the circumferential direction about the tire building drum D, as reflected by the values 0 , +180 and -180 on the vertical axes . Consequently, the other two-dimensional views V2-V5 may show dif ferent tire-related features of the one or more tire components T , for example further contours G2-G5 of a liner, a body ply, a breaker ply, a bead, a side wall , a preassembly, a chafer, a cap strip or a tread . Specifically, these contours G2-G5 can be used to determine lateral positioning and/or alignment of side edges , splices , j oints or the like . Further virtual boundaries R6-R9 are provided in the other two-dimensional views V2-V5, representative of one or more tolerance ranges relevant to the contours G2-G5 as shown . The outer limits of said further virtual boundaries R6-R9 are shown in dashed lines . A first virtual boundary R1 of the virtual boundaries R1-R5 will be discussed below in more detail . It will however be appreciated that the same applies , mutatis mutandis, to the other virtual boundaries R2-R5 as well .

As shown in figure 6, the first virtual boundary R1 comprises a first boundary line El and a second boundary line E2 parallel to and spaced apart from the first boundary line El , representative of a lower limit and an upper limit, respectively, of a first tolerance range . In this example, the first virtual boundary R1 further comprises a third boundary line E3 and a fourth boundary line E4 extending perpendicular to the first boundary line El and the second boundary line E2 to form a boundary box E . The boundary box E defines a rectangular, square or box-shaped area . Preferably, the box-shaped area is provided with a pattern, for example a hatch pattern, or a transparent fill to visually distinguish said box-shaped area from the rest of the respective view VI .

The third boundary line E3 and the second boundary line E4 may be solely used to close the box-shaped area . However, the additional boundary lines E3 , E4 may also be representative of a lower limit and an upper limit , respectively, of a second tolerance range of the one or more tolerance ranges . For example , the first boundary line El and the second boundary line E2 may define a first tolerance range in a first direction, for example a height direction, whereas the third boundary line E3 and the fourth boundary line E4 may be representative of a second tolerance range in a second direction, perpendicular to the first direction, for example in a width direction .

It will be appreciated that the virtual boundaries R1-R9 do not necessarily have to be closed . They also do not necessarily need to have to be linear or rectangular . In some cases , a tolerance range may be applied to an angle, a curvature or another parameter, requiring a di fferent kind of visuali zation which also falls within the scope of the present invention . Note that the first marking Z 1 is provided in the first two-dimensional view VI where, based on the scans , the one or more tire components T are out of a first tolerance range represented by said first virtual boundary R1 . In particular, the aforementioned control unit 7 is used to determine or calculate which part of the detected contour G1 of the splice S is out of the tolerance range . This information is subsequently used to determine which part of the contour G1 should be marked with the first marking Z l .

Based on the information provided by both the first marking Zl and the first virtual boundary Rl , the human operator can more accurately assess the reason for the marking, as well as the severity of the tolerance exceedance relative to the first virtual boundary Rl . It is to be understood that the above description is included to illustrate the operation of the preferred embodiments and is not meant to limit the scope of the invention . From the above discussion, many variations will be apparent to one skilled in the art that would yet be encompassed by the scope of the present invention .

LIST OF REFERENCE NUMERALS

1 system

2 drive

3 manual control

4 scanner

5 pro j ector

6 visual user interface

60 electronic visual display

7 control unit

8 encoder

101 alternative system

106 visual user interface

160 augmented reality device

161 glasses 201 further alternative system

206 visual user interface

260 augmented reality device

261 screen

262 camera

306 visual user interface

Al drum axis

A2 virtual axis

AR augmented reality

B viewing angle

C orientation view

D tire building drum

El first boundary line

E2 second boundary line

G1 first contour

G2 second contour

G3 third contourG4 fourth contour

G5 fifth contour

I scan

K offset

L table

M virtual model

Pl real world angular position

P2 virtual angular position

R1 first virtual boundary

R2 second virtual boundary

R3 third virtual boundary

R4 fourth virtual boundary

R5 fifth virtual boundary

R6 sixth virtual boundary

R7 seventh virtual boundary

R8 eighth virtual boundary

R9 ninth virtual boundary

S splice

T tire ply

V virtual representation

VO three dimensional view VI first two dimensional view

V2 second two dimensional view

V3 third two dimensional view

W wireless connection X irregularity

Z1 first marking

Z2 second marking