Method and device for inspecting a moving apparatus

Abstract

An inspection device (2) for an apparatus with one or more moving components includes an illumination module (10) with an LED array (11) comprising a plurality of LEDs (110) and a co-focus lens array (12) comprising a corresponding plurality of total internal reflection, TIR, lenses (120) each configured to receive light from one of the LEDs (110) and output collimated light directed at a fixed illumination point in a path of the moving components. An image capturing module (20) includes two or more cameras (21) arranged to capture images of the illumination point, and a processing module (30) is configured to determine a gap size between two adjacent components at the illumination point using the images captured by the cameras (21).There is also provided a method for inspecting an apparatus.

Description

[0001] METHOD AND DEVICE FOR INSPECTING A MOVING APPARATUS

[0002] FIELD OF THE DISCLOSURE

[0003] The present technology relates to the inspection of a mechanical apparatus and, in particular, to a device and method for inspecting an apparatus, such as an escalator, where one or more components of the apparatus are in motion.

[0004] BACKGROUND OF THE DISCLOSURE

[0005] When inspecting a mechanical apparatus having one or more moving components, it is important to inspect the gap between adjacent components, where one or both of the adjacent components are capable of moving.

[0006] Gap measurement can be done manually using a feeler gauge 1 , as shown in Fig. 1A. The feeler gauge 1 has a triangular wedge shape with markings to show the width of the wedge at regular increments. As shown in Fig. 1 B, the wedge can be inserted into a gap and the marking located at the opening of the gap can be read or marked e.g. with a user’s finger or otherwise. The reading indicates the width of the feeler gauge 1 at the opening of the gap and therefore provides the width of the gap.

[0007] Using a feeler gauge 1 in this way requires the moving mechanical apparatus to be stopped. Measuring a large apparatus is inefficient and time consuming because each gap must be measured in turn. In addition, accuracy can be low due to individual variations in the angle, force and extent of insertion.

[0008] Stereo machine vision technologies are suitable for many inspection tasks. However, generally the apparatus must be stopped or moving at a low speed to prevent motion blur. In addition, a large baseline between cameras may be required to provide the accuracy needed for inspecting small gaps, and a large baseline can cause problems when inspecting complex apparatuses such as escalators. Such problems may include difficulties in reaching certain inspection sites, and the occlusion of one or both cameras by other nearby components.

[0009] It is an object of the present disclosure to address or at least partially ameliorate some of the above problems of the current approaches.

[0010] SUMMARY OF THE DISCLOSURE Features and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or can be learned by practice of the herein disclosed principles. The features and advantages of the disclosure can be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims.

[0011] In accordance with a first aspect of the present disclosure, there is provided an inspection device for an apparatus with one or more moving components, including an illumination module comprising an LED array comprising a plurality of LEDs, and a co-focus lens array comprising a corresponding plurality of total internal reflection, TIR, lenses each configured to receive light from one of the LEDs and output collimated light directed at a fixed illumination point in a path of the moving components; an image capturing module comprising two or more cameras arranged to capture images of the illumination point; and a processing module configured to determine a gap size between two adjacent components at the illumination point using the images captured by the cameras.

[0012] The image capturing module may be configured to activate for a microsecond exposure time.

[0013] Each TIR lens may have a truncated conical form comprising a recess to receive the LED at the apex, wherein the sloped sides are angled to form total-internal-reflected light from the LED towards the base.

[0014] The base of at least one TIR lens may be angled to direct collimated light to a common point at a fixed working distance.

[0015] The processing module may be configured to identify at least one feature of interest on each component in the captured images, compare the images from each camera to determine a pixel shift for the features, calculate a relative position for the components based on the pixel shift and a known baseline for the image capturing module, and determine the gap size based on the relative position of the components.

[0016] The relative position for each component may be determined based on an average pixel shift for a plurality of features of interest.

[0017] The illumination module may further include a laser with a diffractive optical element configured to output an active light pattern.

[0018] The active light pattern may include a plurality of parallel lines. The processor module may be configured to use gamma calibration on the captured images to increase a contract between the components and the gap between them.

[0019] The image capturing module may include at least three cameras.

[0020] The cameras may be configured to capture colour images, and the processing module may be configured to use the colour images to identify one or more features based on colour.

[0021] The cameras may be configured to generate RGB monochromatic images, and the processing module may be configured to select one of the monochromatic images in order to filter one or more substantially monochromatic sources of noise.

[0022] The processing module may be configured to assess wear-and-tear for one or more 3D features on a component of the apparatus.

[0023] The device may further comprise a mounting structure configured to support the inspection device in a fixed position with respect to the apparatus.

[0024] The mounting structure may include a fixing arrangement configured to attach the inspection device to a non-moving component of the apparatus.

[0025] The fixing arrangement may include a brace configured to support the mounting structure between two opposing surfaces of the apparatus.

[0026] In accordance with a second aspect of the present disclosure, there is provided a method of inspecting an apparatus with one or more moving components, including illuminating a fixed illumination point in a path of the moving components using an LED array comprising a plurality of LEDs and a co-focus lens array comprising a corresponding plurality of total internal reflection, TIR, lenses each configured to receive light from one of the LEDs and output collimated light directed at the fixed illumination point; capturing images of the illumination point from two or more cameras; and determining a gap size between two adjacent components at the illumination point using the images captured by the cameras.

[0027] Capturing the images may include activating the cameras for a microsecond exposure time.

[0028] Determining the gap size may include identifying at least one feature of interest on each component in the captured images, comparing the images from each camera to determine a pixel shift for the features, calculating a relative position for the components based on the pixel shift and a known baseline for the cameras, and determining the gap size based on the relative position of the components. The relative position for each component may be determined based on an average pixel shift for a plurality of features of interest.

[0029] Illuminating the fixed illumination point may include outputting an active light pattern using a laser with a diffractive optical element.

[0030] The active light pattern may include a plurality of parallel lines.

[0031] Determining the gap size may include using gamma calibration on the captured images to increase a contract between the components and the gap between them.

[0032] Capturing the images may include capturing images from at least three cameras.

[0033] The captured images may include colour images, and determining the gap size may include identifying one or more features based on colour using the colour images.

[0034] The captured images may include RGB monochromatic images, and the method may include filtering one or more substantially monochromatic sources of noise by selecting one of the monochromatic images.

[0035] The method may include assessing wear-and-tear for one or more 3D features on a component of the apparatus.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended Figures. Understanding that these Figures depict only exemplary embodiments of the disclosure and are not therefore to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail through the use of the accompanying Figures.

[0038] Preferred embodiments of the present disclosure will be explained in further detail below by way of examples and with reference to the accompanying Figures, in which:-

[0039] FIG 1 A illustrates an example of a feeler gauge according to the prior art.

[0040] FIG. 1 B illustrates an example of the prior art feeler gauge in use.

[0041] FIG. 2 illustrates an example of an inspection device according to an embodiment. FIGS. 3Ato 3C illustrate an example of an illumination module according to an embodiment.

[0042] FIGS. 4A and 4B illustrate an output of the illumination module according to an embodiment.

[0043] FIGS. 5A and 5B illustrate an operation of a processing module according to an embodiment.

[0044] FIG. 6 illustrates an example of an inspection device according to an embodiment.

[0045] FIGS. 7A and 7B illustrate an operation of the inspection device according to an embodiment.

[0046] FIG. 8 illustrates a method of inspecting an apparatus with one or more moving components, according to an embodiment.

[0047] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0048] Various embodiments of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without departing from the scope of the disclosure.

[0049] Referring to the drawings, there is shown in Fig. 2 an inspection device 2 for an apparatus with one or more moving components. The inspection device 2 comprises an illumination module 10, an image capturing module 20 and a processing module 30.

[0050] The illumination module 10 comprises an LED array 11 and a co-focus lens array 12. The LED array 11 comprises a plurality of LEDs 110. The co-focus lens array 12 is configured to direct light from the LEDs 110 to a fixed illumination point in a path of the moving components.

[0051] The image capturing module 20 comprises two or more cameras 21 arranged to capture images of the illumination point.

[0052] The processing module 30 is configured to determine a gap size between two adjacent components at the illumination point using the images captured by the cameras 21 .

[0053] By assessing visually at a defined illumination distance, the inspection device 2 can be fixed in position and used to measure a plurality of points on the apparatus e.g. the gap between steps on an escalator, as they move past the illumination point, or the gap between the moving steps and the comb plate at each end of the escalator. In this way, an apparatus with moving components can be checked without stopping the apparatus. By using at least two cameras 21 the gap can be accurately measured using stereo vision. In addition, stereo vision can be used to assess wear and tear of the moving components, as described in more detail below. Fig. 3A shows a plan view of the illumination module 10. The co-focus lens array 12 of the illumination module 10 comprises a plurality of total internal reflection, TIR, lenses 120. The number of TIR lenses 120 corresponds to the number of LEDs 110 in the LED array 11 .

[0054] In some examples, as shown, the number of LEDs 110 and TIR lenses 120 may be 11. Alternatively, the LED array 11 may comprise a greater or lesser number of LEDs 110, as required. In some examples, the illumination module 10 may include a plurality of LED arrays 11 and a corresponding plurality of co-focus lens arrays 12. For example, the illumination module 10 may include two symmetric LED arrays 11 , with a corresponding co-focus lens array 12 for each LED array 11.

[0055] As shown, each TIR lens 120 may be co-located with one of the LEDs 110. Each TIR lens 120 is configured to receive light from one of the LEDs 110 and output collimated light directed at a fixed illumination area which is in the path of the moving components.

[0056] In some examples, each LED 110 may have a correlated colour temperature between 4000k and 7000k. In this way, the colour of the output light can be optimised for colour image capturing.

[0057] Fig. 3B shows a cross section view of a TIR lens 120 with a corresponding LED 110. In some examples, each TIR lens 120 may have a truncated conical form. The TIR lens 120 may include a recess 121 to receive the LED 110 at the apex. The sloped sides 122 may be angled to form total-internal-reflected light from the LED 110 towards the base 123. In some examples, the sloped sides 122 may have a compound form, with a plurality of sections having different slope angles. For example, as shown in Fig. 3b, the sloped sides 122 may have two sections with different slope angles. In some examples, a greater number of sections may approximate a curved profile. In some examples, at least a portion of the sloped sides 122 may be curved.

[0058] As shown in Fig. 3B, rays of light from the LED 110 may be refracted on entry into the TIR lens 120. For example, the rays may be refracted towards the normal. Ray which are incident on the sloped side walls 122 may be totally internally reflected. In this way, the rays may be deflected towards the base 123 of the TIR lens 120. In this way, the light directed to the base 123 of the TIR lens 120 can be substantially collimated.

[0059] In this way, the TIR lenses 120 can increase the efficiency and intensity of the output illumination. The design of each TIR lens 120 can result in collimated light which does not disperse with distance. In this way, the lens design can improve the efficiency and intensity of illumination. This can have the effect of reducing the exposure time necessary to image a moving structure without blurring.

[0060] In some examples, the base 123 of the TIR lens 120 may be angled. The substantially collimated rays of light incident on the base 123 may be refracted upon leaving the TIR lens 120. For example, the rays may be refracted away from the normal. By selecting the angle of the base 123, the output light from the TIR lens 120 can be directed in a specified direction.

[0061] Fig. 3C shows a side elevation view of the co-focus lens array 12. As shown, the bases 123 of some or all of the TIR lenses 120 may be angled to direct collimated light to a common point at a fixed working distance.

[0062] Fig. 4A shows a perspective view of two illumination modules 10, substantially as described above. The two illumination modules 10 may be configured to direct collimated light to the same common point at the same working distance.

[0063] Fig. 4B shows a representation of the light received at the common point shown in Fig. 4A. As shown, the collimated light output by the TIR lenses 120 can provide a consistent light intensity level across the area of interest. In this way, the area of interest can be illuminated more efficiently.

[0064] Fig. 5A shows a pair of images captured by the image capturing module 20. For example, each of the images may be captured by one of the two or more cameras 21 . The images may show the same illumination point from two different angles, according to the relative positions of the cameras 21.

[0065] In some examples, the image capturing module 20 may be configured to activate for a microsecond exposure time. In this way, the image capturing module 20 can reduce blur and improve accuracy when the apparatus is moving. In some examples, the processing module 30 is configured to use gamma calibration on the captured images to increase a contract between the components and the gap between them. By fine tuning a gamma coefficient of the image, the processing module 30 can ensure that the gap is dark and highlight the groove edges.

[0066] In some embodiments, the processing module 30 may be configured to identify at least one feature of interest on each component in the captured images. For example, where the component is a moving step on an escalator, the processing module 30 may identify one or more groove or tooth features of the step edge. The identified features of interest may be adjacent to the gap between components. Alternatively, the identified features may have a known spatial relationship which the gap. The processing module 30 may be configured to compare the images from each camera 21 to determine a pixel shift for the features. As shown, the two images may be from different cameras 21 designated “L”, “M” and / or “R”. The images may be directed to the same common point, however, the angle may be different due to a baseline distance between the cameras 21. The differing angle may result in a pixel shift due to the parallax effect between the two cameras 21.

[0067] The processing module 30 may be configured to calculate a relative position for the components based on the pixel shift and a known baseline for the image capturing module 20.

[0068] In some examples, the cameras 21 may be configured to capture colour images, wherein the processing module 30 is configured to use the colour images to identified one or more features based on colour.

[0069] In some examples, the cameras 21 may be configured to generate RGB monochromatic images, and the processing module 30 is configured to select one of the monochromatic images in order to filter substantially monochromatic sources of noise. For example, typically green or red LEDs installed on the apparatus for safety or as status indicators can be filtered out so as not to interfere with the measurement.

[0070] In some examples, the relative position for each component may be determined based on an average pixel shift for a plurality of features of interest. For example, the pixel shift for features in a similar category e.g. all extruded edges of the teeth on an escalator step, may be averaged to provide a global pixel fitting. In this way, noise in the measurement can be reduced. Sources of noise may include a build-up of dust and / or debris.

[0071] In some embodiments, the processing module 30 is further configured to assess wear-and-tear for one or more 3D features on a component of the apparatus. In some examples, the processing module 30 may use rule-based image processing. For example, the processing module 30 may be configured to compare a pixel shift or calculated position of a feature of interest with a global pixel fitting as described above. Alternatively, in some examples, the processing module 30 may utilise machine learning to assess wear-and-tear, based on the captured images.

[0072] Fig. 5B shows one of the images captured by the image capturing module 20. As shown, the processing module 30 is configured to determine the gap size between the two adjacent components at the illumination point. The processing module 30 may be configured to determine the gap size based on the determined relative position of each component. Fig. 6 shows an exemplary embodiment of the inspection device 2. As described above, the inspection device 2 includes an illumination module 10, an image capturing module 20 and a processing module 30.

[0073] In some embodiments, the illumination module 10 may further include a laser 13 with a diffractive optical element configured to output an active light pattern. The active light pattern may also be known as structured light or a structured light pattern. In some examples, the active light pattern may include a plurality of parallel lines. For example, the active light pattern may include 6 or more parallel lines. Alternatively, in some examples, fewer than 6 lines may be required. In some examples, the illumination module 10 may include a plurality of lasers 13 projecting the same, or different active light patterns. The distance between parallel lines may be approximately 10mm or less at the working distance. In some examples, the distance may be more than 10mm, as required, or the lines may have a variable spacing. Other potential active light patterns may include a grid of lines, a grid or other arrangement of dots, a chequerboard, a pattern of circles, triangles, hexagons or any combination of these patterns. In some examples, the illumination module 10 may project a sequence of patterns.

[0074] In this way, pattern can be used as features of interest for stereo vision. In this way, feature matching between the two or more cameras 21 can be improved. Or feature matching can be performed when there are no significant features of interest on one or both of the components.

[0075] In some examples, the wavelength of the laser 13 may be 650±20nm. In this way, the laser 13 has a red colour compatible with most industrial cameras. Alternatively, the laser 13 may be any other appropriate colour of visible light or may be non-visible e.g. infra-red.

[0076] In some embodiments, the illumination module 10 comprises at least three cameras 21. In this way, occlusions by objects can be prevented, in particular when imaging complex moving structures. For example, if one camera’s view is obstructed by a moving part, images from the other two cameras 21 can be used.

[0077] Fig. 7A shows an exemplary embodiment of the inspection device 2 in use. Also shown is an exemplary mounting structure 3 for the inspection device 2. The mounting structure 3 may be configured to support the inspection device 2 in a fixed position with respect to the apparatus. In some examples, the mounting structure 3 may comprise a fixing arrangement 40, an extendable arm 50, and an angled mount 60.

[0078] The fixing arrangement 40 may be configured to mount onto a fixed part of the apparatus, or a fixed structure nearby. The fixing arrangement 40 configured to attach the inspection device 2 to a non-moving component of the apparatus. In this case, the fixing arrangement 40 is shown as being mounted onto the fixed rail of an escalator.

[0079] The extendable arm 50 is configured to adjust the distance between the fixing arrangement 40 and the inspection device 2. In turn, this can adjust the distance between the inspection device 2 and the apparatus. In this way, the extendable arm 50 allows positioning of the moving components at the inspection point.

[0080] The angled mount 60 is configured to connect the inspection device 2 to the extendable arm 50. In some examples, the angled mount 60 may be configured to slide in a direction perpendicular to the extendable arm 50. In some examples, the angled mount 60 may be configured to pivot. In this way, the angled mount 60 allows positioning of the moving components at the inspection point.

[0081] Also shown is an exemplary control box 4 for the inspection device 2. In some examples, the control box 4 may comprise a battery and a computer terminal. In some examples, the computer terminal may be configured to provide output from the inspection device 2. In some examples, the computer terminal may be configured to receive user input with respect to the inspection device 2 e.g. calibration input. In some examples, the processing module 30 may be implemented as part of the computer terminal.

[0082] Fig. 7B shows a further example of the inspection device 2 in use. Whereas the inspection device 2 in Fig. 7A is mounted so as to image a gap between adjacent steps when in a “stepped” configuration, the inspection device 2 in Fig. 7B is mounted to as to image a gap between adjacent steps when in a “flat” configuration, e.g. at the top or bottom of the escalation.

[0083] Also shown is the exemplary mounting structure 3 in more detail. The fixing arrangement 40 may include a brace configured to support the mounting structure 2 between two opposing surfaces of the apparatus. For example, the fixing arrangement 40 may comprise a spring press rod 41 configured to support the mounting structure 3 between two fixed surfaces e.g. the fixed rails of the escalator.

[0084] Fig. 8 shows method of inspecting an apparatus with one or more moving components, according to an embodiment.

[0085] The method starts at step S01 .

[0086] At step S02 a fixed illumination point in a path of the moving components is illuminated. The illumination point is illuminated using an LED array comprising a plurality of LEDs, and a co- focus lens array comprising a corresponding plurality of total internal reflection, TIR, lenses each configured to receive light from one of the LEDs and output collimated light directed at the fixed illumination point.

[0087] At step S03, images of the illumination point are captured from two or more cameras.

[0088] At step S04, a gap size between two adjacent components at the illumination point is determined using the images captured by the cameras

[0089] The method ends at step S05.

[0090] The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the disclosure as defined in the appended claims.

[0091] For clarity of explanation, in some instances the present technology may be presented as including individual functional blocks including functional blocks comprising devices, device components, steps or routines in a method embodied in software, or combinations of hardware and software.

[0092] Methods according to the above-described examples can be implemented using computerexecutable instructions that are stored or otherwise available from computer readable media. Such instructions can comprise, for example, instructions and data which cause or otherwise configure a general purpose computer, special purpose computer, or special purpose processing device to perform a certain function or group of functions. Portions of computer resources used can be accessible over a network. The computer executable instructions may be, for example, binaries, intermediate format instructions such as assembly language, firmware, or source code. Examples of computer-readable media that may be used to store instructions, information used, and / or information created during methods according to described examples include magnetic or optical disks, flash memory, Universal Serial Bus (USB) devices provided with non-volatile memory, networked storage devices, and so on.

[0093] Devices implementing methods according to these disclosures can comprise hardware, firmware and / or software, and can take any of a variety of form factors. Typical examples of such form factors include laptops, smart phones, small form factor personal computers, personal digital assistants, and so on. Functionality described herein also can be embodied in peripherals or add-in cards. Such functionality can also be implemented on a circuit board among different chips or different processes executing in a single device, by way of further example. The instructions, media for conveying such instructions, computing resources for executing them, and other structures for supporting such computing resources are means for providing the functions described in these disclosures.

[0094] Although a variety of examples and other information was used to explain aspects within the scope of the appended claims, no limitation of the claims should be implied based on particular features or arrangements in such examples, as one of ordinary skill would be able to use these examples to derive a wide variety of implementations. Further and although some subject matter may have been described in language specific to examples of structural features and / or method steps, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to these described features or acts. For example, such functionality can be distributed differently or performed in components other than those identified herein. Rather, the described features and steps are disclosed as examples of components of systems and methods within the scope of the appended claims.

Claims

CLAIMS1 . An inspection device for an apparatus with one or more moving components, comprising: an illumination module comprising: an LED array comprising a plurality of LEDs, and a co-focus lens array comprising a corresponding plurality of total internal reflection, TIR, lenses each configured to receive light from one of the LEDs and output collimated light directed at a fixed illumination point in a path of the moving components; an image capturing module comprising two or more cameras arranged to capture images of the illumination point; and a processing module configured to determine a gap size between two adjacent components at the illumination point using the images captured by the cameras.

2. The inspection device of claim 1 , wherein the image capturing module is configured to activate for a microsecond exposure time.

3. The inspection device of claim 1 , wherein each TIR lens has a truncated conical form comprising a recess to receive the LED at the apex, wherein the sloped sides are angled to form total-internal-reflected light from the LED towards the base.

4. The inspection device of claim 3, wherein the base of at least one TIR lens is angled to direct collimated light to a common point at a fixed working distance.

5. The inspection device of claim 1 , wherein the processing module is configured to identify at least one feature of interest on each component in the captured images, compare the images from each camera to determine a pixel shift for the features, calculate a relative position for the components based on the pixel shift and a known baseline for the image capturing module, and determine the gap size based on the relative position of the components.

6. The inspection device of claim 5, wherein the relative position for each component is determined based on an average pixel shift for a plurality of features of interest.

7. The inspection device of claim 1 , wherein the illumination module further comprises a laser with a diffractive optical element configured to output an active light pattern.

8. The inspection device of claim 7, wherein the active light pattern comprises a plurality of parallel lines.

9. The inspection device of claim 1 , wherein the processor module is configured to use gamma calibration on the captured images to increase a contract between the components and the gap between them.

10. The inspection device of claim 1 , wherein the image capturing module comprises at least three cameras.11 . The inspection device of claim 1 , wherein the cameras are configured to capture colour images, and wherein the processing module is configured to use the colour images to identify one or more features based on colour.

12. The inspection device of claim 1 , wherein the cameras are configured to generate RGB monochromatic images, and wherein the processing module is configured to select one of the monochromatic images in order to filter one or more substantially monochromatic sources of noise.

13. The inspection device of claim 1 , wherein the processing module is further configured to assess wear-and-tear for one or more 3D features on a component of the apparatus.

14. A method of inspecting an apparatus with one or more moving components, comprising: illuminating a fixed illumination point in a path of the moving components using: an LED array comprising a plurality of LEDs, and a co-focus lens array comprising a corresponding plurality of total internal reflection, TIR, lenses each configured to receive light from one of the LEDs and output collimated light directed at the fixed illumination point; capturing images of the illumination point from two or more cameras; and determining a gap size between two adjacent components at the illumination point using the images captured by the cameras.

15. The method of claim 14, wherein capturing the images comprises activating the cameras for a microsecond exposure time.

16. The method of claim 14, wherein determining the gap size comprises identifying at least one feature of interest on each component in the captured images, comparing the images from each camera to determine a pixel shift for the features, calculating a relative position for the components based on the pixel shift and a known baseline for the cameras, and determining the gap size based on the relative position of the components.

17. The method of claim 16, wherein the relative position for each component is determined based on an average pixel shift for a plurality of features of interest.

18. The method of claim 14, wherein illuminating the fixed illumination point further comprises outputting an active light pattern using a laser with a diffractive optical element.

19. The method of claim 18, wherein the active light pattern comprises a plurality of parallel lines.

20. The method of claim 14, wherein determining the gap size comprises using gamma calibration on the captured images to increase a contract between the components and the gap between them.

21. The method of claim 14, wherein capturing the images comprises capturing images from at least three cameras.

22. The method of claim 14, wherein the captured images include colour images, and wherein determining the gap size comprises identifying one or more features based on colour using the colour images.

23. The method of claim 14, wherein the captured images include RGB monochromatic images, and wherein the method further comprises filtering one or more substantially monochromatic sources of noise by selecting one of the monochromatic images.

24. The method of claim 14, further comprising assessing wear-and-tear for one or more 3D features on a component of the apparatus.

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