Description:FORM 2

THE PATENTS ACT, 1970
[39 OF 1970]
&
THE PATENTS RULES, 2003

COMPLETE SPECIFICATION
[See Section 10, Rule 13]

SYSTEM FOR ESTIMATING DIMENSIONS OF SURFACE DEFECTS
BY

PLANYS TECHNOLOGIES PVT. LTD INCORPORATED AS A PRIVATE LIMITED COMPANY RECOGNIZED AS A STARTUP BY THE DEPARTMENT FOR PROMOTION OF INDUSTRY AND INTERNAL TRADE, WHOSE ADDRESS IS NO. 5 JAYA NAGAR EXTENSION, BALAJI NAGAR MAIN ROAD, G.K. AVENUE, PUZHUTHIVAKKAM, CHENNAI 600091, TAMIL NADU, INDIA

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

TECHNICAL FIELD
[001] The present invention relates to a system for estimating and extracting dimensions of surface-breaking defects using visual information only.

BACKGROUND
[002] It is vital to conduct inspections of structures to identify the location and severity of critical defects when analyzing the health of those structures. Knowing the severity of the critical defects is incumbent to plan for repairs and maintenance of the specimen structure. Public infrastructure assets like dams and bridges are too large to feasibly inspect manually. Conventionally, there are many systems and tools available for visual inspections of the structure. However, in such conventional systems, even if the defects are identified in the initial visual screening phase, accessing them for follow up inspections is not always possible. Visual inspections of the specimen structure are typically the initial screening procedures, before more specialized systems are commissioned. However, such conventional systems have significant limitations as they fail to provide any quantitative information about defect size during the initial visual screening phase.
[003] The systems that exist currently to provide quantitative information about defect size are inefficient, complex and expensive. For example, conventionally, measurement of size and depth of the defect is done manually by using gauges and other measurement tools such as micrometers, vernier calipers. The manual measurement of the critical defects on the surface of the structure has significant limitations. Direct access to the structure is required to take manual measurements which may not be possible in-situ as defects may be difficult or dangerous to reach for humans. Another conventional method of measuring the critical defects on the surface of the structure is by acoustic measurement. By sending ultrasonic signals that travel with known velocities through the structure the integrity of the specimen may be analyzed. Defects in the structure impede the acoustic signal and reduce its speed. By measuring the time of flight of the acoustic signal, an estimate of the position and size of the defect may be measured. However, acoustic measurement also has significant limitations as transducers are required to be located directly on the surface of the structure to conduct ultrasonic tests. Also, in some configurations access to both sides of the structure may be required, which may not be possible in all practical situations. Moreover, accuracy of acoustic measurement depends heavily on the surface condition of the structure. Yet another manner of analyzing critical defects includes radiography, in which the structure is scanned by x-rays to highlight internal features. The x-ray source and detector are placed on both sides of the structure and a scan is taken. Rebar, voids, and cracks absorb x-rays at different rates and defects may be identified from the scan. However, radiography has significant limitations as it may not be possible in all practical situations to locate the source and detector on opposite sides of the structure. Electromagnetic techniques are still further conventional ways for analyzing critical defects. For metal specimen structures, eddy current methods reveal information about defect locations and sizes. Coils carrying currents are placed near the specimen surface, inducing eddy currents. These eddy currents create a magnetic field that changes when interacting with defects. However, such conventional electromagnetic techniques have significant limitations as they are limited to metal specimens with surface breaking/subsurface defects. Also, the signals obtained from the electromagnetic techniques are complex and challenging to interpret.
[004] The aforementioned methodologies are also challenging to deploy on surfaces that are too hot or too cold, non-stationary or located in hazardous environments. Further, typically, quantitative information about defects obtained by such conventional methods and systems are required to be performed on pre-screened locations with specialized equipment which requires expertise that may not be readily deployable in all circumstances. Therefore, such methods and systems are ineffective in analysis of a target surface as they fail to provide quantitative information about surface defects in real-time.
[005] Therefore, there exists a need for a system that overcomes one or more of the aforementioned problems.

SUMMARY
[006] Accordingly, an exemplary aspect of the present invention discloses a system for estimating dimensions of surface defects, said system comprising: a laser unit configured to project laser projections onto said surface; an imaging unit configured for capturing a visual of the projected lasers on the surface intersecting the defect in the visual; and a control unit configured for processing and analyzing said captured visual in real-time by initializing measurement of deflections in a spacing indicative of a mapped surface unevenness estimation and quantification of the surface defect depth size.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
[007] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:
[008] Figure 1 illustrates an exemplary view of a system for estimating dimensions of a defect on a surface, according to an exemplary aspect of the present invention;
[009] Figure 2 illustrates an exemplary view from an imaging unit of the system, according to an exemplary embodiment of the present invention showing laser projections interacting with a surface defect;
[010] Figure 3 illustrates an exemplary block diagram of the system, according to the exemplary embodiment of the present invention;
[011] Figure 4 illustrates an exemplary method for estimating dimensions of a defect on a surface, according to another exemplary embodiment of the present invention;
[012] Figure 5 illustrates an exemplary view of flaw gauge with a laser unit and imaging unit, showing parallel laser projections on a surface, according to yet another exemplary embodiment of the present invention;
[013] Figure 6 illustrates an exemplary view of the system with images with defect generated from the imaging unit and calibration of the system with Figure 6A illustrating a deeper defect, and Figure 6B illustrating a shallower defect, according to the exemplary embodiment of the present invention;
[014] Figure 7 illustrates an exemplary relationship between laser spacing and defect depth, according to the exemplary embodiment of the present invention; and
[015] Figure 8 illustrates an exemplary view of the image generated by the image unit showing spacing between the projected laser interacting with defect depth, according to the exemplary embodiment of the present invention.
[016] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to the other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that reference signs are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION
[017] While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail, a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspects of the invention to the embodiment illustrated. Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention. Embodiments of the present disclosure will now be described with reference to the accompanying drawings. Embodiments are provided to convey the scope of the present disclosure thoroughly and fully to a person skilled in the art. Numerous details are set forth relating to specific components to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
[018] In general, the present invention discloses a vision-based, non-contact type for quantitative dimension estimation of a surface defect depth to aid in asset management and structural health monitoring. The present invention, according to an exemplary aspect provides a system for estimating dimensions of surface defects. The present invention further discloses a method and a flaw gauge for estimating dimensions of surface defects. The system comprises a laser unit configured to provide laser projections onto a target specimen surface. The surface has a defect region. The laser projections intersect the target specimen surface with the defect and deviations/deflection in spacing between the laser projections are captured by an imaging unit and processed by a control unit of the system indicate target specimen surface defect depth.
[019] According to an exemplary embodiment of the present invention, the system, flaw gauge and method of the present invention is simple, and low cost. The system of the present invention may be retroactively deployed along with an existing typical visual inspection with pre-existing payloads as an added value and thereby reduce the need for subsequent inspections of the same specimen surface. The quantitative dimension estimation depth in 3D i.e., length, width, and depth of the critical defect is observable on the surface of the specimen surface of interest. The quantitative estimation of the defect depth is obtained from just the visual screening of the specimen surface. The specimen surface may be a structural surface, and the defect may be a structural surface defect without any absorption or reflection from the surface.
[020] The terminology used in the present disclosure is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. As used in the present disclosure, the forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated elements, units and/or components, but do not forbid the presence or addition of one or more other elements, components, and/or groups thereof.
[021] The terms and words used in the following description and claims are not limited to the bibliographical meanings but are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents. Accordingly, it should be apparent to those skilled in the art that the following description of system, flaw gauge and method referred in the description for the purpose of the understanding and nowhere limit the invention. The skilled person will be able to devise various structures, types and shapes of the system, flaw gauge for estimating dimensions of surface defects that, although not explicitly described herein, embody the principles of the present invention. All the terms and expressions in the description are only for the purpose of understanding and nowhere limit the invention. Terms like plurality, first, second, axial, inner, outer, are used to differentiate between objects having the same terminology and are in no way intended to represent a chronological order, unless where explicitly stated otherwise. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof. Thus, while structure of the system, flaw gauge for estimating dimensions of surface defects with desired laser configuration, spacing, mounting shape, material, heights, lengths, widths, distances, angles, inclination, methods, have been disclosed, nowhere limit the invention, and are provided for understanding of the invention. It will be appreciated those of ordinary skill in the art that various changes and modifications of the embodiments manufactured with other design parameters and configurations as well and are not limited to those described herein above may be as per operational requirements by making necessary changes without departing from the scope of the invention.
[022] Figure 1 to 8 illustrate a system (100), a surface (102), a defect (105), a laser unit (110), a visual image (115), a plurality of laser diodes (120), a mount (122), parallel laser projections (125), an imaging unit (130), projected laser lines (140), a control unit (150), a visual unit (160), linear interdependent spacing (S-s), the laser spacing (in pixels) on the surface (ΔP1), the laser spacing (in pixels) on the defect (ΔP2), a method (200) and a flaw gauge (300).
[023] According to an exemplary aspect, the present invention discloses a system (100) for estimating dimensions of a surface (102) defect (105). The surface (102) may be a structural surface, and the defect may be a structural surface defect. The system comprises a laser unit (110) having at least a plurality of laser diodes (120) located within a mount (122). The laser unit is configured for projecting laser projections (125) onto said surface (102) with defect (105). The laser configuration depends on the specific embodiment. The laser projections (125) may be straight laser line projections (140) or a grid laser projection on the surface (102). The system (100) also comprises an imaging unit (130) having at least a sensor coupled to the mount (122) proximate to the laser unit (130). The imaging unit (130) is configured for capturing a visual (115) of the projected lasers (140) on the surface (102) intersecting the defect (105) in the visual (115). The laser projections emitted from the laser unit (130) may be parallel to an optical axis of the imaging unit (130) without orientation and a predefined spacing between the parallel projected lasers is maintained uniform throughout the structural surface defect image. Also, the laser projections emitted from the laser unit (130) may be normal to the surface (102) without orientation or the laser projections emitted from the laser unit (130) may be non-parallel to an optical axis of the imaging unit (130) forming an orientation to the surface (102). The system (100) further comprises a control unit (150) for processing and analyzing generated captured visual image (115) for identification of the structural surface defect (105) and dimension estimation of the structural surface defect (105) with parameters like depth, and size of the defect, thereby quantifying the structural surface defect. The projected lasers (140) on the structural surface (102) defect (105) from the captured visual (115) is processed and analyzed in real-time by the control unit by initializing measurement of any deflection or any deviations in linearity of the projected laser projections spacing (S-s) indicative of a mapped surface unevenness estimation and quantification of the surface defect (105) depth size. The control unit (150) is in communication with a visual unit (160) by a wire, or wirelessly for post-processing and screening of the captured visual (115).
[024] According to the exemplary embodiment, in the system, a predefined wavelength emitted by the lasers from the laser unit is constant with the imaging unit’s sensors’ wavelength sensitivity. The imaging unit utilizes processing, machine or deep learning techniques to (i) calibrate for flaws / defects in the laser unit and the mount, (ii) detect the laser projections, (iii) estimate and quantify the structural surface defect dimensions. The imaging unit captures images that are focused and clear for ensuring accuracy in depth estimation. The size of the defect measurable is interdependent on the spacing between the laser projections and the laser array pattern that intersects with the target defect surface for estimating the surface defect depth. The spacing (S-s) is a uniform or a varying linear interdependent laser pixel spacing including a difference obtained between a laser pixel spacing (ΔP1) formed on the surface (102) minus a laser pixel spacing (ΔP2) formed on the defect (105). The laser unit (150) is mounted proximate to the imaging unit (130) to ensure that orientation of the laser (125) emitted from the laser unit (110) is constant and parallel with predefined spacing. The laser projections according to one embodiment may be normal to the target surface without any significant orientation to the target surface such that the performance of the system and the quality of the captured and extracted image from the imaging unit is not affected, and efficient depth and dimension estimation of the target defect surface is made possible.
[025] According to the exemplary embodiment, in the system, the imaging unit (130) generated visual (115) may be a real-time still image (115) or a real-time video (115) of the surface (102) with the defect (105). Depending on the application, the imaging unit (130) generates and captures visual (115) in different spectra that include but are not limited to infrared, thermal among others. The generated and captured visuals (115) are analyzed by the control unit (150) in communication with the visual unit (160). The acquired visuals may need to undergo pre-processing before being used for defect size estimation. The design of the mount (122) for the laser unit (110) depends on the specific setup for the imaging unit (130). For example, the laser unit (110) may be integral to the imaging unit (130) and part of the system (100, 300). However, if the laser unit (110) is retroactively coupled to existing imaging unit (130) with pre-existing payloads, the mount (122) design takes into consideration aspects of the existing imaging unit (130). Furthermore, the laser unit (110) as per requirement may project lights of different wavelengths, based on the type of imaging device used, conversely, the choice of laser may inform the choice of imaging unit (130).
[026] According to another exemplary embodiment, the present invention discloses a flaw gauge (300) comprising an imaging unit (130) and a laser unit (110) coupled on a mount (122) and interconnected with a control unit (150). The control unit (150) may be configured to toggle the laser unit (110) and the imaging unit (130) externally may be to conserve power, or to give better visibility from the imaging unit (130). The imaging unit (130) is configured to screen a specimen surface of interest, and the laser unit (110) is configured to project laser projections onto the specimen surface such that the projected lasers intersect the specimen surface. The imaging unit (130) has at least a sensor and is configured to capture a visual (115) of the defect (105) along with laser (140) projected on the surface (102) and intersecting the defect (105). The control unit (150) may be in communication with said laser unit (110) and said imaging unit (130) and is configured for processing and analyzing said captured visual (115) in real-time by initializing measurement of deflections in a spacing (S-s) indicative of a mapped surface unevenness estimation and quantification of the surface defect (105) depth size. The control unit (150) may be in communication with a visual unit (160) for aiding in post processing of the data to size defects.
[027] According to the exemplary embodiment, the post-processing of the captured visual (115) includes extracting the pixel separation of the projected lasers (140) and calculating the linear interdependent spacing (S-s) formed between said laser projected on the surface (102) and the defect (105) and surface defect depth size obtained by regression.
[028] According to another exemplary embodiment, the present invention discloses a method (200) for estimating dimensions of surface (102) defects (105). The method (200) comprising the steps of: (210) projecting laser projections (125) by a laser unit (110) onto the surface (102) to interact with the defect (105); (220) capturing by the imaging unit (130) a visual (115) of the defect (105) along with laser (140) projected on the surface (102) and intersecting the defect (105); and (230) measuring by a control unit (150) in communication with said laser unit (110) and said imaging unit (130) for processing and analyzing said captured visual image (115) in real-time by initializing measurement of deflections in a spacing (S-s) indicative of a mapped surface unevenness estimation and quantification of the surface defect (105) depth size. The image may be captured by the imaging unit for laser deflection analysis and defect size estimation. The control unit (150) may be configured for image post processing, data communication and visualization by a visual unit (160).
[029] According to the exemplary embodiment, in the system (100), the laser unit (110) has a configuration of a pair of parallel line lasers (125) and the post processing of the captured image (115) involves obtaining the pixel separation between the laser lines. The control unit (150) measures the measures the laser deflection defect size based on the space difference between the parallel laser lines. The imaging unit (130) efficiency depends upon parameters that include but not limited to a field of view and resolution of a camera of the imaging unit and laser unit configuration.
[030] According to the exemplary embodiment, in the system (100), the exemplary parameters of the relationship between laser spacing and defect depth are obtained by regression. The control unit (150) is configured to measure the extraction of pixel information on an image generated by the imaging unit. From the captured image/visual, the pixel spacing between the line lasers on the specimen and inside the defect are extracted and processed using the relationship obtained from calibration to return the defect depth. The system first undergoes a calibration process to determine the mapping between laser deflection and defect depth. This calibration is required to account for manufacturing imperfections in the laser and its mount. The calibration is performed by placing the imaging unit with the camera and laser setup in front of a specimen with a defect of variable depth. The imaging unit with the camera is placed at a measured distance from the specimen and images are captured from the imaging unit. The spacing between the lasers in the defect region is correlated with the depth of the defect using regression. The setup is then tested on a different defect and the regression is verified.
[031] According to the exemplary embodiment, in the system, the laser unit comprises of two laser diodes having the capacity of 20 mW 650 nm line lasers with a 90-degree fan angle. The line laser diodes are kept as close together as physically possible to minimize the size of defects that may be processed. The laser diode mount is also machined to a high tolerance in order to ensure the projected lasers are parallel.
[032] There have been described and illustrated herein several embodiments of exemplary indicative implementation of system, flaw gauge and method for estimating dimensions of surface defects. It will also be apparent to a skilled person that the embodiments described above are specific examples of a single broader invention, which may have greater scope than any of the singular descriptions taught. There may be many alterations made in the description without departing from the scope of the invention. While embodiments of the invention have been described, it is not intended that the invention be limited to said configuration disclosed thereto, as it is intended that the invention be as broad in scope as the art will allow and that the specification be read likewise not restrictive to the terminology described herein above. Any discussion of embodiments included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
, Claims:
1. A system (100) for estimating dimensions of surface (102) defects (105), said system (100) comprising:
a laser unit (110) configured to project laser projections (125) onto said surface (102);
an imaging unit (130) configured for capturing a visual (115) of the projected lasers (140) on the surface (102) intersecting the defect (105) in the visual (115); and
a control unit (150) configured for processing and analyzing said captured visual (115) in real-time by initializing measurement of deflections in a spacing (S-s) indicative of a mapped surface unevenness estimation and quantification of the surface defect (105) depth size.

2. The system (100) as claimed in claim 1, wherein said laser projections (125) are straight laser line projections (140) or a grid laser projection on the surface (102).

3. The system (100) as claimed in claim 1 or 2, wherein said laser projections (125) are parallel to an optical axis of the imaging unit (130) and normal to the surface (102) without orientation or at least said two laser projections (125) are non-parallel to the optical axis of the imaging unit (130) forming an orientation to the surface (102).
4. The system (100) as claimed in anyone of the preceding claims 1-3, wherein said laser unit (110) is proximate to said imaging unit (130) and includes two laser diodes (120) located within a mount (122).

5. The system (100) as claimed in anyone of the preceding claims 1-4, wherein said spacing (S-s) is a uniform or a varying linear interdependent laser pixel spacing including a difference obtained between a laser pixel spacing (ΔP1) formed on the surface (102) and a laser pixel spacing (ΔP2) formed on the defect (105).

6. The system (100) as claimed in anyone of the preceding claims 1-5, wherein said control unit (150) is in communication with a visual unit (160) by a wire, or wirelessly for post-processing and screening of the captured visual (115).

7. The system (100) as claimed in anyone of the preceding claims 1-6, wherein said visual (115) is a real-time still image or a real-time video of the surface (102) with the defect (105).

8. The system (100) as claimed in anyone of the preceding claims 1-7, wherein said visual (115) is an infrared or a thermal visual.

9. The system (100) as claimed in anyone of the preceding claims 1-8, wherein said laser unit (110) is integral to the imaging unit (130) or is retroactively coupled to existing imaging unit (130) with pre-existing payloads.
10. The system (100) as claimed in anyone of the preceding claims 1-9, wherein said control unit (150) is configured to toggle the laser unit (110) and the imaging unit (130) externally.