Method for measuring geometric deviations between the curved surfaces of a plurality of materials to be assessed and a curved surface of a reference material

Description

[0001] The present invention relates to the field of control of the reliefs of curved surfaces of materials, in particular the curved surfaces of glazing adapted to means of transport, in particular for the automobile industry.

[0002] Its subject is a method and a system for measuring geometric deviations between the curved surfaces of a plurality of materials to be evaluated and a curved surface of a reference material.

[0003] The relief and general curvature of material surfaces, particularly curved surfaces, can constitute prohibitive quality criteria if they do not meet the constraints provided for their applications or uses.

[0004] For example, in the glass industry, the manufacture of glazing for applications in the field of means of transport such as motor vehicles often includes a step of shaping mineral glass sheets in order to give them a certain curvature. This curvature, the radii of curvature of which can vary along the entire surface of the glass sheet, is necessary so that the glazing formed by the glass sheets is suitable for being fixed or inserted on or into the vehicle frame. This contributes, among other things, to the general aesthetics sought by the vehicle manufacturer, the mechanical, thermal and acoustic performances of the areas where the glazing is fixed and inserted into the frame, as well as the optical performances of the glazing depending on whether it is used as a windshield or side glazing.

[0005] Customers, such as vehicle manufacturers, integrators and / or processors, thus define strict specifications on acceptable tolerances for the surface condition of glazing in terms of its relief and / or the geometry of its curvature. Generally, a model glazing, physical or digital, is established for the particular application on a vehicle, for example a windshield, and on which control points are defined. These control points can correspond to fixing areas on the vehicle frame or even vision areas for the driver and / or passengers.

[0006] Ideally, no relief or surface geometry defects should be present at these control points; at most, the characteristics of the defect should be within the tolerances acceptable to the customer(s). In all cases, a defect, if present, should not be likely to interfere with the fixing of the glazing to the vehicle, nor be likely to reduce the driver's visual comfort or interfere with driving the vehicle. Similarly, if the glazing is used in a digital display device such as a plasma screen or a liquid crystal display or includes such a device, no defect should disrupt the display.

[0007] Numerous methods for controlling the quality of glazing have been developed to isolate and eliminate those whose optical characteristics are unsuitable for their intended use. These methods are often implemented during or after manufacture. They are described in detail in the state of the art.

[0008] For example, patent applications EP1176388A2, US5426861, DE102006016677, WO2016052248, JP09257657 and EP453433A2 disclose general methods for measuring materials. Patents EP 0463940 B and EP 0342127 B describe automated methods for optically inspecting glazing in which the levels of optical deformation of the glazing are determined from a shadow image and then compared to previously defined threshold values. Patent applications WO 98 / 17993 and GB 2152210 as well as patent EP 1061357 B disclose methods for detecting optical anomalies in a transparent sheet by analyzing the image of a geometric pattern reflected or transmitted by the sheet.

[0009] However, these methods do not allow the insulation of glazing whose glass sheets have, on the surface, geometric differences in relief or curvature with the surface of a model glazing.

[0010] There are also contact devices or methods for determining whether the contours of an article, such as a glass sheet, match those of a template. For example, US 3733704 A describes a support whose periphery is provided with a plurality of feeler potentiometers, and on which an object is arranged so that the feeler potentiometers determine its contour. US 4221053 A describes a device having the desired shape for the glass sheet to be examined and whose periphery is provided with a plurality of feeler potentiometers. A glass sheet is arranged under the device so that the feeler potentiometers, upon contact with the surface of the glass sheet, determine its contour to verify that it matches that of the device. US 4679331 A discloses a device comprising an articulated arm on which a single feeler potentiometer is fixed.The articulated arm moves to certain points on the periphery of a glass sheet placed on a template and brings the feeler potentiometer into contact with the surface of the glass sheet. A difference in thickness between the surface of the glass and the surface of the template is calculated. This difference indicates whether the outline of the glass sheet matches that of the template.

[0011] These contact methods and devices have several drawbacks. First of all, they require, for each glass sheet shape, a specially designed and adapted template. In an industrial context where a certain flexibility and responsiveness are required in view of the rapid evolutions of customers' technical needs, this generates additional delays and costs related in particular to the development of a template for each shape and for its maintenance. This also creates risks of degradation, such as scratches or scrapes, and / or pollution of the surfaces of the glass sheets, especially when the templates and the means of surface detection by contact deteriorate due to their natural wear. Secondly, the use of means of surface detection by contact, such as touch potentiometers, is unsuitable for certain articles.The particular case of glazing comprising thin mineral glass, generally between 0.4 mm and 1.5 mm thick, is particularly illustrative. Due to its low thickness, thin glass is sensitive to any mechanical surface stress. This can result in optical deformations that are prohibitive for certain applications. Contact-based surface detection methods should therefore be avoided. Finally, these contact devices and methods are unsuitable for measuring geometric deviations at any point on a surface in a time compatible with the pace of a production line. Measuring geometric deviations at any point using these contact devices and methods is slow. Exploring an entire surface takes too long for them to be effectively incorporated into a high-speed continuous production line.

[0012] The present invention solves these problems. It relates to an automated method for measuring geometric deviations in curvature between the curved surfaces of a plurality of materials to be evaluated and a curved surface of a reference material according to claim 1.

[0013] The invention also relates to a system making it possible to implement the method of the invention according to claim 11. [ Fig.1 ] is a schematic representation of an embodiment of a method and system according to the invention. [ Fig.2 ] is a graphical representation of an example of a trajectory defined for the measurement of optical deviations according to the method of the invention. [ Fig.3 ] is a schematic representation of a manufacturing line integrating a method and a system according to the invention. [ Fig.4 ] is a schematic representation of a second embodiment of a method according to the invention [ Fig.5 ] is a schematic representation of a third embodiment of a method according to the invention.

[0014] In the rest of the text, he refers to the elements of the figures in their different views.

[0015] There Figure 1 represents an embodiment of a method according to the invention.

[0016] The method according to the invention is an automated method 1000 for measuring geometric deviations in curvature between the curved surfaces 1001a of a plurality of materials 1001 to be evaluated and a curved surface 1001a of a reference material 1001 (not shown). For the purpose of simplifying the figures, the materials to be evaluated and the reference material are represented by the same element 1001 in the figures.

[0017] The process includes the following steps: (a) measuring, at selected measurement points along a defined trajectory 1001b, the curvature profile of the curved surface 1001a of the reference material 1001 using a non-contact detection means 1002, said non-contact detection means 1002 being arranged on an automatic movement means 1003 traveling along said trajectory 1001b synchronously with the measurement of the curvature by the non-contact detection means 1002; (b) measuring the curvature profile of the curved surface 1001a of each material 1001 to be evaluated, at the same measurement points selected along the same trajectory 1001b, under the same conditions of travel of said trajectory 1001b by the automatic displacement means 1003 and according to the same acquisition angle by the contactless detection means 1002 at the same measurement point as for the curved surface 1001a of the reference material during step (a);(c) calculating, implemented by computer (not shown), at the selected points, the difference between the curvature profiles of the curved surface 1001a of each evaluation material 1001 obtained in step (b) and the curvature profile of the curved surface 1001a of the reference material 1001 obtained in step (a).;

[0018] The angle of the acquisition axis of the contactless detection means 1002 may advantageously be between 0 and 40°, preferably between 0 and 20°, relative to the normal to said curved surface at the measurement point. Such an angle may make it possible, for example, to avoid measurement artifacts which may appear when too large an area of ​​the curved surfaces is measured by the contactless detection means 1002.

[0019] The automatic moving means may be arranged on a fixed support 1005 adapted and located so as to enable it to reach all or part of the points of the curved surfaces of the materials to be evaluated and of the reference material. The support may also be a mobile support. Similarly, the materials to be evaluated and the reference material may be arranged on a fixed support 1004. The support 1004 may also be mobile. This is the case, for example, of a conveyor which transports said materials and which is temporarily immobilized while carrying out a measurement of the geometric deviations according to the method of the invention.

[0020] In some applications, the required characteristics or acceptable tolerances for the curvature of the curved surface of the materials may vary. For example, in the case of glazing for transport vehicle applications, the acceptable tolerances for curvature in areas of the glazing intended to be fixed to the vehicle frame may be different from those in areas intended to serve as vision areas for the vehicle driver.

[0021] In this sense, in an embodiment of the method according to the invention, said method may further comprise, after step (c), a step (d) of comparing, at selected measurement points, the values ​​of the differences calculated during step (c) with tolerance values ​​previously defined at each of said points. The selected measurement points may be just a few points along the trajectory, all of the points forming the trajectory and include measurement points outside of said trajectory.

[0022] For example, the Figure 2 represents, a top view, a curved surface 1001a of a reference material 1001 or of a material to be evaluated. On this surface is represented an example of trajectory 2001 that the method according to the invention allows to configure and travel for the measurement of the curvature profile of the curved surface 1001a. Measurement points 2002, 2003 can be selected on the trajectory 2001 or outside. This figure illustrates the flexibility of the method of the invention in that it allows to adapt the trajectories 1001b and measurement points according to the type of material and its use and to compare the curvature values ​​with tolerance values ​​defined for each of these points.

[0023] Today, most automatic displacement means 1003 and contactless detection means 1002 are controlled and interfaced using computer systems comprising computing means capable of processing instructions to operate them. When such systems are used, the trajectory 1001b along which the curvature profile of the curved surfaces 1001a is measured can advantageously be defined using a digital model of the reference curved surface. Such a model can, for example, be produced using computer-aided design software.

[0024] The method according to the invention involves the use of the spatial coordinates of the points of the trajectory 1001b along which the measurement of the curvature is carried out. These coordinates can be defined according to a reference frame located in the space of the trajectory 1001b likely to be traveled along the curved surfaces 1001a of the materials or in the reference frame of the assembly formed by the automatic displacement means and the contactless detection means. The reference frame of the assembly formed by the automatic displacement means 1003 and the contactless detection means 1002 is generally the reference frame of the automatic displacement means 1003.

[0025] In general, the automatic movement means 1003 are controlled using one or more control devices to which instructions are communicated in order to move these automatic means along a defined trajectory 1001b. The spatial coordinates of this trajectory 1001b are then often defined in the reference frames specific to the automatic movement means 1003. However, in practice, and in particular in a production site, the spatial coordinates of the trajectory 1001b, along which the measurement of the curvature of the curved surfaces 1001a is carried out, are defined in another external reference frame, such as that of the production site or that of a manufacturing process or device.It is therefore, in these cases, advantageous to calibrate the movements of the assembly formed by the automatic movement means 1003 and the contactless detection means 1002 in the external reference frame in order to ensure that said assembly follows the correct trajectory 1001b and that this path is reproducible.

[0026] In this sense, it may be advantageous for the method of the invention to further comprise, before step (a), a step (a') of calibrating the reproducibility of the spatial positions of the assembly formed by the automatic displacement means 1003 and the means 1002 of contactless detection in the space of the trajectory likely to be traveled in step (a), said step (a') comprising the following sub-steps: (a'1) the definition of a plurality of calibration points of known spatial coordinates in a first reference frame in space comprising the trajectory 1001b likely to be traveled in step (a); (a'2) the acquisition by the assembly formed by the automatic displacement means 1003 and the contactless detection means 1002 of the spatial coordinates of said calibration points in the reference frame of said assembly formed by the automatic displacement means 1003 and the contactless detection means 1002; (a'3) the calculation, implemented by computer, of the statistical correlation function between the spatial coordinates obtained in step (a'1) and the spatial coordinates obtained in step (a'2); (a'4) the implementation of the statistical correlation function in a device for controlling the movements of said assembly formed by the automatic displacement means and the contactless detection means.

[0027] The statistical correlation function can be a linear or multilinear regression function. It can also be calculated using a statistical learning algorithm. In particular, the calculation of the statistical correlation function is performed using a least squares regression method.

[0028] The method according to the invention can be integrated into a continuous manufacturing process of materials. Steps (b) and (c) of the method can then be carried out successively and continuously on the curved surfaces of the materials. Figure 3 represents an example of a manufacturing line in which the method of the invention is integrated. The line 3000 comprises a conveyor 3001 on which glass sheets 3002 originating in the manufacturing process (not shown) are conveyed. The glass sheets 3002 having a curved surface are moved to a first automaton 3003 having gripping means so as to transport a glass sheet 3002a onto a fixed support 3004. A system 3005 comprising an automatic movement means on which a contactless detection means is fixed implements the method of the invention. The measurement, at selected measurement points along a defined trajectory, of the profile of the curvature of the curved surface of a reference glass sheet has been previously carried out.

[0029] If the geometric deviations in curvature between the curved surfaces of the glass sheet 3002a and the curved surface of the reference glass sheet do not meet the desired criteria, the latter is downgraded or discarded on a support 3006 provided for this purpose. If they are satisfactory, the glass sheet 3002a is preserved and stacked on a support (not shown) provided for this purpose, in preparation, for example, for its shipment to the customer. Each glass sheet 3002 brought by the conveyor 3001 is successively treated in this way.

[0030] In the method according to the invention, the materials to be evaluated and the reference material, and consequently their respective curved surfaces, are arranged horizontally or with a certain inclination. Figure 4 is a schematic representation of the method of the invention in which the glazing 1001 is inclined.

[0031] In particular, the curved surfaces 1001b of the evaluation materials 1001 and the reference material 1001 may be spatially oriented at angles of inclination corresponding to those likely to be expected during their use. Such an arrangement may, for example, make it possible to take into account mechanical deformations of the material and its curved surface which may potentially form under the conditions of its use.

[0032] For example, a laminated glazing made of mineral glass, such as a windshield for a transport vehicle, is generally not arranged horizontally on the vehicle but has a certain inclination relative to the vertical. Furthermore, this glazing is generally fixed to the vehicle frame by its periphery. Such a configuration is likely to cause a deformation of the curvature of its surface, especially if it is large and fairly thin. The method of the invention can make it possible, to the extent of geometric deviations, to take into account this deformation of the curvature by arranging the glazing in a spatial orientation according to the angle of inclination corresponding to its use. It is also possible to arrange it on a support simulating these conditions of fixing to the vehicle frame.

[0033] The contactless detection means 1002 may be a chromatic confocal sensor. The operation of chromatic confocal sensors is based on a division of an electromagnetic beam into different wavelengths depending on the distance from the output objective of said beam. They make it possible to measure the height of the reliefs of a surface with a high lateral resolution. The use of a chromatic confocal sensor, in particular a digital chromatic confocal sensor, may be advantageous in that this type of sensor allows contactless measurement with an acquisition frequency and a resolution compatible with an automatic movement means capable of high movement speeds.This type of sensor is also particularly suitable for transparent materials, such as mineral glass sheets, for which optical sensors requiring reflective or opaque surfaces to operate are unsatisfactory.

[0034] The automatic movement means 1003 may be an articulated automated arm with six degrees of freedom. The use of such an arm has the advantage of ensuring the reproducibility of the path of a trajectory along curved surfaces, and of limiting variations in the height of the detection means relative to the curved surface, particularly in areas of high curvature.

[0035] The method of the invention is particularly suitable for measuring the curvature deviations between the curved surfaces 1001a of a plurality of transparent materials 1001 to be evaluated and a curved surface 1001a of a transparent reference material 1001. More specifically, it is suitable for quality control of the curved surfaces of the glass sheets at the end of production or after their shaping, for example by bending. In this sense, the reference materials and the evaluation material are respectively a reference glass sheet and evaluation glass sheets. Also, the reference glass sheet and the evaluation glass sheets may be capable of constituting the glass sheets of a reference glazing for a means of transport and evaluation glazings for the same means of transport respectively.

[0036] In one embodiment, illustrated in the figure 5, the method of the invention comprises a second assembly comprising a second automatic displacement means 5001 on which is fixed a second non-contact detection means (not shown). This second assembly can operate simultaneously with the first assembly comprising the first automatic displacement means 1003 and the first non-contact detection means 1002 in the execution of steps (a) and (b) of the method of the invention. A first advantage is a faster execution of the method of the invention. A second advantage is that it is possible to measure geometric deviations of curvature on curved surfaces 1001a of large dimensions for which a single automatic displacement means may be unsuitable. A third advantage is that the first and second assemblies can have a reduced spatial footprint and, thus, be suitable for sites where there is little space.

[0037] The invention also relates to a system for implementing the method according to the invention. The system is an automatic system for measuring the geometric deviations of curvature between the curved surfaces 1001a of a plurality of materials 1001 to be evaluated and a curved surface 1001a of a reference material 1001, the reference material and the materials to be measured being respectively a reference glass sheet and evaluation glass sheets, said system comprising an assembly formed by at least one automatic displacement means 1003 adapted for traveling at least one trajectory 1001b defined along the curved surfaces 1001a, and at least one contactless detection means 1002 adapted for measuring the curvature of curved surfaces 1001a, arranged on the automatic displacement means 1003 and synchronized with the movements of said automatic displacement means 1003; said system being configured to: measuring, at selected measuring points along a defined trajectory 1001b, the curvature profile of the curved surface 1001a of the reference material 1001, and measuring the curvature profile of the curved surface 1001a of each material 1001 to be evaluated, at the same selected measuring points along the same trajectory 1001b, under the same conditions of travel of said trajectory 1001b by the automatic displacement means 1003 and according to the same acquisition angle by the contactless detection means 1002 at the same measuring point as for the curved surface 1001a of the reference material 1001.

[0038] The system according to the invention further comprises a calculation unit configured to calculate, at selected points, the difference between the curvature profiles of the curved surfaces 1001a of each evaluation material 1001 and the curvature profile of the curved surface 1001a of the reference material 1001.

[0039] The contactless detection means 1002 is fixed to the automatic displacement means 2003 using a fixing means. Any suitable fixing means can be used. Preferably, the fixing means can have a thermal conductivity allowing the heat linked to heating of the contactless sensor to be evacuated. Such heating is in fact likely to disrupt its operation, in particular, when it is an electronic detection means, by the appearance of electronic noise disturbing its signal. Such heating can, for example, be caused by prolonged use of the contactless detection means. The fixing means can advantageously have a thermal conductivity greater than 100 WK -1< .m -1< , preferably greater than 200 WK 1< .m -1< . An example of a suitable material for the fixing means is aluminum.

[0040] The automatic displacement means 1003 may be an articulated automated arm with six degrees of freedom. The use of such an articulated arm is advantageous in that it is sufficiently flexible to adapt to any type and degree of curvature of the curved surfaces. Positioning of the non-contact detection means with respect to the curved surfaces is facilitated.

[0041] The contactless detection means of the system according to the invention is a chromatic confocal sensor.

[0042] In order to allow spatial orientation of the curved surfaces according to angles of inclination corresponding to those likely to be expected during their use, the system may advantageously comprise, in addition to a support for the evaluation materials and the reference material, such that the curved surfaces of the evaluation materials and the reference material are spatially oriented according to angles of inclination corresponding to those likely to be expected during their use.

[0043] The method and system according to the invention provide the following advantages: they can be used for the quality control of the curvature of curved surfaces of materials sensitive to any mechanical surface stress; they can be integrated into continuous manufacturing, design or assembly lines; the quality control of the curvature of the curved surfaces of a plurality of materials to be evaluated is automated and can be carried out along any trajectory or at certain defined points of this trajectory; the trajectory along which the quality of the curvature is controlled can be adapted according to the type of materials and their use; no template, such as those described in the prior art, is required to carry out the quality control of the curvature of the curved surfaces; the risks of degradation and / or pollution of the curved surfaces are eliminated.

Claims

1. An automated method (1000) for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface of a reference material (1001), the reference materials (1001) and the assessment material (1001) being, respectively, a reference sheet of glass and assessment sheets of glass, said method comprising the following steps: (a) the measurement, at selected measurement points along a defined trajectory (1001b), of the curvature profile of the dished surface (1001a) of the reference material (1001) using a contactless detection means (1002), said contactless detection means (1002) being disposed on an automatic displacement means (1003) travelling along said trajectory synchronously with the measurement of the curvature profile by the contactless detection means (1002); (b) the measurement of the curvature profile of the dished surface (1001a) of each material (1001) to be assessed, at the same selected measurement points along the same trajectory (1001b), in the same conditions of travel along the said trajectory (1001b) by the automatic displacement means (1003) and according to the same angle of acquisition by the contactless detection means (1002) at the same measurement point as for the dished surface (1001a) of the reference material (1001) during the step (a); (c) the calculation, implemented by computer, at the selected points, of the difference between the curvature profiles of the dished surface (1001a) of each material (1001) to be assessed obtained in the step (b) and the curvature profile of the dished surface (1001a) of the reference material (1001) obtained in the step (a).

2. The automated method for measuring geometric deviations of curvature between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in claim 1, such that it further comprises, after the step (c), a step (d) of comparison, at selected measurement points, of the values of the differences calculated during the step (c) with tolerance values previously defined at each of said points.

3. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 and 2, such that it further comprises, before the step (a), a step (a') of calibration of the reproducibility of the spatial positionings of the assembly formed by the automatic displacement means (1003) and the contactless detection means (1002) in the space of the trajectory (1001a) likely to be travelled along in the step (a), said step (a') comprising the following substeps: (a'1) the definition of a plurality of points of calibration of known spatial coordinates in a first reference frame of reference in the space of the trajectory (1001a) likely to be travelled along in the step (a); (a'2) the acquisition by the assembly formed by the automatic displacement means (1003) and the contactless detection means (1002) of the spatial coordinates of said calibration points in the reference frame of reference of said assembly formed by the automatic displacement means (1003) and the contactless detection means (1002); (a'3) the calculation, implemented by computer, of the statistical correlation function between the spatial coordinates obtained in the step (a'1) and the spatial coordinates obtained in the step (a'2); (a'4) the implementation of the statistical correlation function in a device for controlling the movements of said assembly formed by the automatic displacement means (1003) and the contactless detection means (1002).

4. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in claim 3, such that the calculation of statistical correlation function is performed using a least squares regression method.

5. Automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 to 4, such that the steps (b) and (c) are executed successively and continually on the dished surfaces of the materials.

6. Automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 to 5, such that the trajectory (1001b) is defined using a digital model of the reference dished surface.

7. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 to 6, such that the dished surfaces (1001a) of the assessment materials (1001) and of the reference material (1001) are spatially oriented according to angles of inclination corresponding to those likely to be provided during their use.

8. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 to 7, such that the contactless detection means (1002) is a chromatic confocal sensor.

9. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in one of claims 1 to 8, such that the automatic displacement means (1003) is an articulated automaton arm provided with six degrees of freedom.

10. The automated method for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in claim 1, such that the reference sheet of glass and the assessment sheets of glass are likely to form glass sheets of a reference glazing for a transportation means and assessment glazings for the same transportation means respectively.

11. An automatic system for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001), the reference materials (1001) and the assessment material (1001) being, respectively, a reference sheet of glass and assessment sheets of glass, said system comprising an assembly formed by - at least one automatic displacement means (1003) adapted to travel along at least one trajectory (1001b) defined along dished surfaces (1001a), and - at least one contactless detection means (1002) adapted to measure the curvature of dished surfaces (1001a), disposed on the automatic displacement means (1003) and synchronized with the movements of said automatic displacement means (1003), the contactless detection means (1002) being a chromatic confocal sensor ; said system being configured to: - measure, at selected measurement points along a defined trajectory (1001b), the curvature profile of the dished surface (1001) of the reference material, and - measure the curvature profile of the dished surface (1001a) of each material (1001) to be assessed, at the same selected measurement points along the same trajectory (1001b), in the same conditions of travel along said trajectory (1001b) by the automatic displacement means (1003) and according to the same angle of acquisition by the contactless detection means (1002) at the same measurement point as for the dished surface (1001a) of the reference material (1001), the system further comprising a computation unit configured to calculate, at the selected points, the difference between the relief height or curvature profiles of the dished surfaces (1001a) of each assessment material (1001) and the relief height or curvature profile of the dished surface (1001a) of the reference material.

12. The automatic system for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material as claimed in claim 11, such that the contactless detection means (1002) is disposed on the automatic displacement means (1003) using a fixing means having a thermal conductivity greater than 100 W.K-1.m-1, preferably greater than 200 W.K-1.m-1.

13. The automatic system for measuring geometric curvature deviations between the dished surfaces (1001a) of a plurality of materials (1002) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in any one of claims 11 to 12, such that the automatic displacement means (1003) is an articulated automaton arm provided with six degrees of freedom.

14. The automatic system for measuring geometric relief or curvature deviations between the dished surfaces (1001a) of a plurality of materials (1001) to be assessed and a dished surface (1001a) of a reference material (1001) as claimed in any one of claims 11 to 13, such that it further comprises a support for the assessment materials (1001) and for the reference material (1001) such that the dished surfaces (1001a) of the assessment materials (1001) and of the reference material (1001) are spatially oriented according to angles of inclination corresponding to those likely to be provided during their use.