Method and device for measuring the wear of the discs of an aircraft brake and associated computer program

Abstract

The invention relates to a method for measuring the wear of the discs of an aircraft brake provided with a wear indicator (6) movably mounted on a fixed part of the aircraft brake and moving as the discs wear, the method comprising the steps of: - acquiring an image of a portion of the discs of the aircraft brake, - identifying the wear indicator (6) in the acquired image, - identifying at least three reference points (A1, B1, C2) on the wear indicator (6), and - determining at least one measurement of the wear of the discs of the aircraft brake by determining at least one dimension (L, W) associated with the wear indicator (6) from the three identified reference points (A1, B1, C2).

Description

DESCRIPTION Method and device for measuring wear on aircraft brake discs and associated computer program TECHNICAL FIELD OF THE INVENTION

[0001] The technical field of the invention is that of the control of parts of an aircraft, and in particular the control of the discs of an aircraft brake.

[0002] The present invention relates to a method and a device for measuring wear on the discs of an aircraft brake. It also relates to an associated computer program.

[0003] The present invention finds advantageous application for the control of aircraft, such as airplanes or helicopters. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0004] Aircraft brakes typically consist of a stack of discs (also called "heat sinks") that are pressed against each other by pistons to generate a braking moment to slow down the wheel to which the brake is attached. Discs are subject to wear with each braking application. It is therefore important to be able to monitor their wear in order to plan their replacement (particularly so that aircraft braking is not affected).

[0005] In this regard, aircraft brakes are generally equipped with a wear indicator which is slidably mounted relative to a fixed part of the brake. This wear indicator is arranged so as to remain in contact with one of the faces of the stack of discs in such a way that the wear indicator moves as the discs wear. The position of the wear indicator is therefore indicative of the state of wear of the stack of discs.

[0006] Maintenance operators therefore regularly check the position of the wear indicator (typically weekly) to verify the state of wear of the discs, and replace them with new discs if the wear indicator reaches a maximum wear position. This manual check is not optimal, particularly because it requires the operator to approach the disc stack, which is very hot (several hundred degrees Celsius) following a braking operation. In addition, the accuracy i the measurement of the wear indicator remains quite limited, with an error of the order of a millimeter.

[0007] Document FR3068098 discloses a method for measuring wear on aircraft brake discs based on acquiring a photograph of the wear indicator. This photograph is combined with known information about the aircraft, and in particular the number of flights made by the aircraft, to determine an estimate of the position of the wear indicator.

[0008] However, this method does not allow the length of the wear indicator to be obtained explicitly and precisely, which would then make it possible to concretely characterize the state of wear of the aircraft brake discs. SUMMARY OF THE INVENTION

[0009] The present invention proposes to improve the determination of wear of the discs of an aircraft brake by explicitly quantifying this wear by means of an optical measurement of the wear indicator.

[0010] More particularly, the invention proposes a method for measuring the wear of the discs of an aircraft brake provided with a wear indicator mounted movably on a fixed part of the aircraft brake and moving as the discs wear, the method comprising steps of: - acquisition of an image of part of the aircraft brake discs, - identification of the wear indicator in the acquired image, - identification of at least three reference points on the wear indicator, and - determination of at least one measurement of wear of the aircraft brake discs by determining at least one dimension associated with the wear indicator from the three identified reference points.

[0011] Thus, advantageously according to the invention, the wear measurement method makes it possible to evaluate the state of wear of the aircraft brake discs remotely on the basis of an image acquired from the wear indicator. The analysis of this image then makes it possible to quantify the state of wear of the aircraft brake discs by measuring at least one dimension associated with this wear indicator. This measurement is carried out on the basis of at least three reference points, which makes it possible to obtain a reliable and precise measurement of the characteristics of the wear indicator.

[0012] Furthermore, no material modification needs to be made to the aircraft brake to enable the wear condition of the aircraft brake discs to be assessed. No additional material costs are therefore incurred and the method according to the invention can be implemented on any aircraft.

[0013] Finally, thanks to the present invention, the state of wear of the aircraft brake discs can be determined without risk (i.e. without getting too close to the heat sink whose temperature is very high), in an automated and precise manner thanks to the marks identified on the wear indicator.

[0014] In addition to the characteristics which have just been mentioned in the preceding paragraph, the wear measurement method according to one aspect of the invention may have one or more additional characteristics among the following, considered individually or according to all technically possible combinations: - at the stage of determining the wear measurement of the aircraft brake discs, the determination of the width and length of the wear indicator from the three identified reference points is provided; - there is provided, before the step of identifying the at least three reference points, a step of delimiting a reduced part of the acquired image and comprising the wear indicator, the identification of the at least three reference points being implemented from this reduced part of the acquired image; - the identification of the wear indicator in the acquired image is implemented by means of an artificial neural network, the acquired image being provided as input to said artificial neural network so as to obtain, as output to said artificial neural network, an area of ​​the acquired image on which the wear indicator is identified; - the identification of at least three reference points is implemented by analyzing the area of ​​the acquired image obtained at the output of the artificial neural network; - the artificial neural network is a convolutional artificial neural network; - prior to the image acquisition stage, a stage of learning the artificial neural network from a set of basic images is planned; - the identification of the at least three reference points on the wear indicator is implemented by means of another artificial neural network, the acquired image in which the wear indicator has been identified being provided as input to said other network of artificial neurons so as to obtain, at the output of said other artificial neural network, coordinates of at least three reference points; - the other artificial neural network is a convolutional artificial neural network; - the reduced part of the acquired image is provided as input to the other artificial neural network so as to obtain, as output from said other artificial neural network, the coordinates of the at least three reference points; - prior to the image acquisition step, a step of learning the other artificial neural network from another set of basic images is planned; - before the step of determining the wear measurement of the aircraft brake discs, a step of identifying at least one other reference point is provided, the determination of the wear measurement of the aircraft brake discs being implemented taking into account this other reference point; and - the at least three reference points correspond to visible ends of the wear indicator.

[0015] The invention also relates to a device for measuring wear on the discs of an aircraft brake provided with a wear indicator mounted movably on a fixed part of the aircraft brake and moving as the discs wear, the device comprising: - a module for acquiring an image of part of the aircraft brake discs, - a module for identifying the wear indicator in the acquired image, - an identification module of at least three reference points on the wear indicator, and - a module for determining at least one measurement of wear of the aircraft brake discs by determining at least one dimension associated with the wear indicator from the three identified reference points.

[0016] The invention finally relates to a computer program comprising instructions executable by a processor and designed to implement a method as defined previously when these instructions are executed by the processor.

[0017] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0018] The figures are presented for information purposes only and in no way limit the invention.

[0019] Figure 1 schematically represents an aircraft brake as considered in the present invention,

[0020] Figure 2 is a partial schematic representation of the aircraft brake of Figure 1 emphasizing a wear indicator included in that aircraft brake,

[0021] Figure 3 represents, in functional form, an example of a device for measuring wear on the discs of an aircraft brake designed to implement a method for measuring wear on the discs of an aircraft brake according to the invention,

[0022] Figure 4 represents, in the form of a flowchart, an example of a method for measuring wear on aircraft brake discs in accordance with the invention,

[0023] Figure 5 illustrates step E2 of the wear measurement method shown in Figure 4,

[0024] Figure 6 illustrates step E4 of the wear measurement method shown in Figure 4,

[0025] Figure 7 illustrates step E6 of the wear measurement method shown in Figure 4, and

[0026] Figure 8 illustrates steps E8 and E10 of the wear measurement method shown in Figure 4. DETAILED DESCRIPTION

[0027] The present invention is placed in the context of monitoring the brakes of an aircraft. More particularly, the invention aims to enable the monitoring of the wear of the aircraft brake discs. In particular again, the invention aims to quantify, that is to say measure, the wear of the aircraft brake discs, in particular to be able to predict their replacement.

[0028] The aircraft is for example an airplane or a helicopter.

[0029] Figure 1 shows an aircraft brake 1. The aircraft brake 1 itself does not constitute the core of the present invention. It is therefore not described in detail here.

[0030] Essentially, this aircraft brake 1 comprises a torque tube on which a stack 2 of discs is stacked. This stack 2 of discs is commonly called a "heat sink".

[0031] The stack 2 of discs comprises, in a conventional manner, an alternation of stator discs 2A and rotor discs 2B.

[0032] This stack 2 of discs is arranged so as to extend between a hydraulic crown 3 and a plate 5 fixed to the other end of the torque tube. The hydraulic crown 3 is provided with a plurality of pistons 4 positioned between this hydraulic crown 3 and the stack 2 of discs.

[0033] In practice, the aircraft brake 1 thus formed is positioned on an axle of an aircraft landing gear (not shown). This aircraft landing gear receives a wheel whose rim comprises bars for driving the rotor discs 2B into rotation.

[0034] In order to characterize the wear of the discs of the aircraft brake 1, this brake 1 is provided with a wear indicator 6. This wear indicator 6 is more particularly represented in FIG. 2. Preferably, at least two wear indicators 6 are present in the aircraft brake 1.

[0035] As shown more particularly in Figure 2, this wear indicator 6 is here in the form of a cylindrical metal rod. This metal rod is slidably mounted on the hydraulic crown 3. It is required to remain in contact with the stack 2 of discs, so that the wear indicator 6 is moved towards the stack 2 of discs as the discs wear.

[0036] For this, in practice, the wear indicator 6 is for example driven by a plate (not shown in the figures) positioned between the stack 2 of discs and the hydraulic crown 3. Alternatively, a spring system can be used so as to keep the wear indicator 6 in contact with the stack 2 of discs.

[0037] As indicated above, the present invention aims to quantify, that is to say measure, the wear of the aircraft brake discs. In practice, the state of wear of the aircraft brake discs 1 can be quantified by determining the dimensions of the wear indicator 6 protruding from the hydraulic crown 3. Indeed, the more the aircraft brake discs 1 are worn, the more the wear indicator 6 is moved towards the stack 2 of discs. The length L of the wear indicator 6, outside the crown hydraulic 3 (i.e. opposite the stack 2 of discs) therefore reduces as the discs of the aircraft brake 1 wear. The present invention therefore aims to determine these dimensions of the wear indicator 6 so as to quantify the state of wear of the discs of the aircraft brake 1.

[0038] In practice, this is implemented by means of a device 10 for measuring the wear of the aircraft brake discs 1.

[0039] Figure 3 represents, in functional form, the device 10 for measuring wear on the discs of the aircraft brake 1 (also referred to as device 10 in the following).

[0040] As shown in Figure 3, the device 10 includes a processor 20 and a storage device 24.

[0041] The storage device 24 is, for example, a hard disk or a memory. The storage device 24 is here designed to store reference values, such as, for example, a maximum wear length used when implementing a wear measurement method as described below.

[0042] The device 10 also comprises a set of functional modules. It comprises, for example, an image acquisition module 12, a first identification module 14, a second identification module 16 and a module 18 for determining a wear measurement.

[0043] Each of the different modules described is for example implemented by means of computer program instructions stored in the storage device 24 and designed to implement the module concerned when these instructions are executed by the processor 20 of the wear measuring device 10.

[0044] However, as a variant, at least one of the aforementioned modules may be produced by means of a dedicated electronic circuit, for example an application-specific integrated circuit.

[0045] In other words, the wear measurement method according to the invention and described in the remainder of the document is implemented here by computer. Preferably, the wear measurement device 10 is for example embedded in a smartphone (or “smartphone” according to the commonly used English term). This allows in particular a more practical implementation of the wear measurement method according to the invention (because the aircraft brake 1 is often in a restricted space with rather limited access).

[0046] The processor 20 is also designed to implement a first artificial neural network NN1 and a second artificial neural network NN2, involved in the method for measuring wear of the aircraft brake discs 1 described below. This first artificial neural network NN1 and this second artificial neural network NN2 are presented in more detail below.

[0047] The device 10 is designed to implement the method for measuring wear on aircraft brake discs according to the invention.

[0048] Figure 4 is a flowchart representing an example of a method for measuring wear on the discs of the aircraft brake 1 implemented in the context described above.

[0049] This wear measurement method is for example implemented by the processor 20. Generally, this wear measurement method is implemented by computer. As indicated previously, the wear measurement method is for example implemented from an application embedded in a smart phone (or “smartphone”).

[0050] As shown in Figure 4, the wear measurement method begins at step E2 of acquiring an image Im of a portion of the aircraft brake discs. This image Im is for example acquired by an image acquisition device embedded for example on a smartphone. Figure 5 represents an example of an image Im acquired during this step E2.

[0051] In step E4, the processor 20 analyzes the image Im acquired (in step E2) and determines whether the wear indicator 6 is present on this image Im. In other words, step E4 aims to identify the presence of the wear indicator 6 on the image Im acquired. Figure 6 illustrates this step E4.

[0052] In practice, in the example of the wear measurement method described here, the identification of the wear indicator 6 in the image Im (acquired in step E2) is implemented by means of the first artificial neural network NN1.

[0053] The processor 20 then provides, as input to this first artificial neural network NN1, the image Im acquired (in step E2). This first neural network artificial NN1 is designed to provide as output a zone Z1 of the acquired Im image on which the wear indicator 6 is identified.

[0054] This first artificial neural network NN1 therefore presents an object detection function (here the wear indicator 6) in an image provided as input (here the acquired image Im).

[0055] The first artificial neural network NN1 is here a convolutional artificial neural network. For example, this is a YOLO type artificial neural network (for "You Only Look Once" according to the commonly used Anglo-Saxon term). As is known, this type of artificial neural network allows, from an image provided as input, to detect and classify objects present in this image provided as input. More details concerning this YOLO type of artificial neural network can be found in the article by Joseph Redmon et al., "You Only Look Once: Unified, Real-Time Object Detection", 779-788, 10.1109 / CVPR.2016.91, 2016.

[0056] In other words, the first artificial neural network NN1 is designed to detect an area Z1 of the acquired image Im which comprises the wear indicator 6. Figure 6 represents the area Z1 identified on the image Im acquired in step E2 by the implementation of the first artificial neural network NN1.

[0057] Prior to implementing the wear measurement method, a learning step (not shown in the figures) allows the training of this first artificial neural network NN1. For this, a set of basic images is used. For each basic image of this set on which the wear indicator 6 is present, an area which includes this wear indicator 6 is identified. Each basic image of this set which does not represent the wear indicator is associated with information of the absence of this wear indicator (no area is therefore associated with this corresponding basic image). The weights of the neurons are then adjusted as the learning step progresses.

[0058] If, in step E4, the first artificial neural network NN1 does not provide any area of ​​the acquired image Im, this means that the wear indicator 6 is not visible on this acquired image Im. The wear measurement method then resumes in step E2, with the acquisition of a new image.

[0059] If, on the contrary, in step E4, the first artificial neural network NN1 provides, as output, a zone Z1 of the acquired image Im comprising the wear indicator 6 (as is the case in FIG. 6), the wear measurement method continues in step E6. This therefore means that the wear indicator 6 is visible on the image Im and that it will be possible to analyze the dimensions of this wear indicator 6 to characterize the wear of the discs of the aircraft brake 1.

[0060] As shown in Figure 4, the wear measurement process continues to step E6. This step E6 is illustrated in Figure 7.

[0061] During this step, the processor 20 determines a part Im1 of the reduced image Im and comprising the identified wear indicator 6. In other words, during this step E6, the processor 20 restricts the image Im to a part Im1 comprising the wear indicator 6 and an environment close to it. This part Im1 is visible in FIG. 7.

[0062] In practice, the part Im1 comprises for example the wear indicator 6 and an additional margin (for example of the order of 25%, in pixels, in all directions) around this wear indicator 6. As a variant, the part Im1 may have a predetermined dimension smaller (while comprising the wear indicator 6) than the dimension of the image Im (acquired in step E2).

[0063] This step E6 is optional here but it is advantageous because it allows to obtain a reduced-sized image including the wear indicator. This then allows a faster implementation of the wear measurement (which is based on image analysis) and also less expensive in computing resources.

[0064] The wear measurement is implemented by means of an image analysis on which the wear indicator 6 is visible. It is carried out either directly from the image Im acquired (in step E2), or from the part Im1 obtained in step E6.

[0065] The wear measurement method then continues with step E8. During this step E8, the processor 20 identifies at least three reference points A1, B1, C2 on the wear indicator 6. These reference points A1, B1, C2 are marks identified on the wear indicator 6 which will make it possible to carry out the wear measurement of the discs of the aircraft brake 1. Step E8 therefore aims to identify marks, on the wear indicator 6, which will make it possible to characterize the wear indicator 6 so as to evaluate its state of wear. Step E8 is illustrated in Figure 8.

[0066] In practice, these reference points A1, B1, C2 correspond for example to specific points of the wear indicator 6 such as its free ends or its ends at the level of the hydraulic crown 3. These are in particular visible ends, on the image Im or the part Im1, of the wear indicator 6. Here, the two reference points A1, B1 are located at the end of the wear indicator 6 positioned at the level of the hydraulic crown 3. The third reference point C2 is located at the level of the free end 6A of the wear indicator 6.

[0067] In the example of the wear measurement method described here, the identification of the at least three reference points A1, B1, C2 (in the image Im or in the part Im1) is implemented via the second artificial neural network NN2.

[0068] The processor 20 then provides, as input to this second artificial neural network NN2, the image Im (acquired in step E2) or the part Im1 (determined in step E6) on which the wear indicator 6 is present. This second artificial neural network NN2 is designed to provide as output coordinates of the three reference points A1, B1, C2. These coordinates are for example here expressed in pixels of the image Im or of the part Im1.

[0069] This second artificial neural network NN2 therefore presents here a function of visual recognition of object markers (here the reference points A1, B1, C2 of the wear indicator 6) in an image provided as input (here the image Im acquired in step E2 or the part Im1 obtained in step E6).

[0070] The second artificial neural network NN2 is here a convolutional artificial neural network. It is for example an artificial neural network of the HR-Net type (for "High-Resolution Network" according to the commonly used Anglo-Saxon term). As is known, this type of artificial neural network allows, from an image provided as input, to detect objects, classify images or implement a semantic segmentation of the pixels of the image (i.e. to assign a category to each pixel of the image provided as input). More details concerning this HR-Net type of artificial neural network can be found in the article "Deep High-Resolution Representation Learning for Visual Recognition,” by Jingdong Wang et al., arXiv:1908.07919, August 20, 2019.

[0071] Alternatively, the second artificial neural network may be of the YOLO type (as described above). Alternatively, the second artificial neural network may be of the LiteNet type (for "Lightweight Neural Network" according to the commonly used English term). These variants require less computing power and are therefore more suitable, for example, for implementation in a smartphone.

[0072] Thus, the second artificial neural network NN2 is designed to identify at least three reference points A1, B1, C2 on the wear indicator 6 which will make it possible to characterize it. More particularly, these reference points A1, B1, C2 will make it possible to characterize the wear of the brake discs by determining dimensions associated with the wear indicator 6 (and derived from these three reference points A1, B1, C2).

[0073] Prior to implementing the wear measurement method, a learning step (not shown in the figures) allows the training of this second artificial neural network NN2. For this, another set of basic images is used. The wear indicator 6 is visible on each of the images of this other set. For each basic image of this other set, three reference points on this wear indicator 6 are identified. The weights of the neurons are then adjusted as the learning step progresses.

[0074] At the end of step E8, the processor 20 therefore has three reference points A1, B1, C2 associated with the wear indicator 6 visible on the image Im (or on the part Im1) and which will make it possible to characterize the wear of the aircraft brake discs.

[0075] As shown in Figure 4, the wear measurement method continues in step E10. During this step, the processor 20 identifies at least one other reference point C1, A2, B2, A3, B3, C3 on the wear indicator 6. This other reference point C1, A2, B2, A3, B3, C3 is distinct from the three reference points A1, B1, C2 identified in step E8.

[0076] The other reference point C1, A2, B2, A3, B3, C3 has the same characteristics as the three reference points A1, B1, C2 identified in step E8: it also forms a mark identified on the wear indicator 6 and which will make it possible to characterize the wear of the aircraft brake discs 1.

[0077] The other reference point C1, A2, B2, A3, B3, C3 is also identified here through the implementation of the second artificial neural network NN2 described previously.

[0078] Here, as shown in Figure 8, six other reference points C1, A2, B2, A3, B3, C3 are for example identified. Among these six other reference points C1, A2, B2, A3, B3, C3, two of them A2, B2 correspond for example to reference points associated with the free end of the wear indicator 6.

[0079] Two other reference points A3, B3 correspond to other reference points located at the end of the wear indicator 6 positioned at the level of the hydraulic crown 3. These two other reference points A3, B3 (associated with the hydraulic crown 3) are particularly advantageous because they make it possible to compensate for any bias in the wear measurement which would be associated with the angle of the shot (for the acquired image Im).

[0080] This step E10 is optional but it is advantageous because it allows for a greater number of reference points to be available for measuring the wear of the aircraft brake discs. This then makes it possible to improve the accuracy of the wear measurement, in particular by limiting the perspective effects associated with the shooting angle (of the acquired Im image).

[0081] The wear measurement method then continues with a step E12 of determining at least one wear measurement of the discs of the aircraft brake 1. More particularly, this wear measurement is implemented by determining at least one dimension associated with the wear indicator 6.

[0082] The dimension associated with the wear indicator 6 is for example here the length L or the width W of the visible wear indicator 6 identified on the acquired image Im. Preferably, the length L and the width W of the wear indicator 6 are determined in step E12 so as to improve the characterization of the wear of the discs of the aircraft brake 1.

[0083] In practice, the dimension associated with the wear indicator 6 is here determined from the three reference points A1, B1, C2 identified in step E8. More particularly, the reference points A1, B1 make it possible to determine the width W of the wear indicator 6. The middle of the reference points A1, B1 and the reference point C2 allow, for their part, to determine the length L of the wear indicator 6.

[0084] In practice, these dimensions are determined in pixels on the acquired image Im or on the part Im1. The processor 20 then converts the dimensions in pixels obtained into dimensions in the metric system.

[0085] For this, the diameter of the wear indicator 6 is used as reference data. This diameter corresponds to the width W of the wear indicator 6 measured on the image Im (or on the part Im1). The diameter of the wear indicator 6 therefore serves here as calibration data to deduce therefrom (by a rule of proportionality) the other dimensions of the wear indicator 6 (and in particular the length L of the wear indicator 6). For example, the wear indicator 6 here has a diameter less than 8 millimeters (mm), for example of the order of 7.94 mm.

[0086] Finally, the width W of the determined wear indicator 6 makes it possible to deduce the length L of the wear indicator 6, which is the particularly relevant dimension for evaluating the wear of the aircraft brake discs 1.

[0087] Thus, in step E12, the processor 20 has a dimension (here the length) of the wear indicator 6 visible on the acquired image Im (or on the part Im1) from which the wear of the discs of the aircraft brake 1 will be evaluated.

[0088] Optionally, if step E10 described previously has been implemented, the processor 20 has the three reference points A1, B1, C2 as well as the other reference points C1, A2, B2, A3, B3, C3 to determine the wear measurement of the aircraft brake discs 1.

[0089] The two reference points A1, B1 allow a first width W1 to be determined. The other two reference points A2, B2 allow a second width W2 to be determined.

[0090] The width W of the wear indicator 6 is determined from the first determined width W1 and the second determined width W2. More particularly, the width W of the wear indicator 6 is determined as being the average of the first width W1 and the second width W2.

[0091] The use of the two width values ​​(of the first width W1 and of the second width W2), each determined at one end of the wear indicator 6, is particularly advantageous because it makes it possible to limit the perspective effects associated with the shooting angle (of the acquired image Im). This then makes it possible to improve the determination of the width W of the wear indicator 6 from the acquired image Im (or of the part Im1).

[0092] This width W also serves here as a calibration for determining the length L of the wear indicator 6 as described previously (given that the diameter of the wear indicator 6 is known).

[0093] The use of the other reference points C1, A2, B2, A3, B3, C3 makes it possible to refine the determination of the length L of the wear indicator 6. The reference point C2 serves as the first end for the determination of the length L of the wear indicator 6.

[0094] A second end for determining the length L of the wear indicator 6 is determined from the different reference points A1, B1, C1, A3, B3, C3.

[0095] A first intermediate point C1 is determined as the barycenter of the two reference points A1, B1. A second intermediate point C3 is determined as the barycenter of the other two reference points A3, B3.

[0096] The second end for determining the length L of the wear indicator 6 is for example here determined as the middle between the first intermediate point C1 and the second intermediate point C3. The definition of the second end for determining the length L of the wear indicator 6 is particularly advantageous because it makes it possible to limit the perspective effects associated with the viewing angle (of the acquired image Im). Indeed, by using only the first intermediate point C1, a bias could exist if the viewing angle is not exactly implemented at 90 degrees (this would then lead to an overestimation of the length of the wear indicator). This then makes it possible to improve the accuracy of the determined length L of the wear indicator 6.

[0097] The length L is then determined as the distance between, on the one hand, the barycenter of the first intermediate point C1 and the second intermediate point C3, and, on the other hand, the reference point C2. This length L is obtained here in pixels but converted into the metric system thanks to the calibration carried out from the known diameter of the wear indicator 6.

[0098] Thus, at the end of step E12, the processor 20 has a dimension (here the length) of the wear indicator 6 which will make it possible to conclude as to the wear of the discs of the aircraft brake 1.

[0099] More precisely, in step E14, the processor 20 determines the wear of the discs of the brake 1 of the aircraft by comparing the value of the dimension obtained in step E12 with a predefined value. This predefined value is associated with a maximum wear length of the wear indicator 6 (indicating wear of the discs of the aircraft brake 1 requiring the replacement of these discs of the aircraft brake 1). This maximum wear length is for example stored in the storage device 24 of the wear measuring device 10. This maximum wear length is for example here of the order of 1 millimeter (mm).

[0100] Thus, if the length L determined in step E12 is less than or equal to the stored maximum wear length, the processor 20 sends an alert signal indicating the wear of the discs of the brake concerned (step E16). This alert signal is presented for example in the form of a notification displaying a message recommending the replacement of the discs of the aircraft brake 1. For example here, a length L less than or equal to 1 mm leads to a flight ban for the aircraft, notified in the alert signal sent in step E12.

[0101] Otherwise, if the length L determined in step E12 is greater than the maximum wear length stored, the method resumes at step E2.

[0102] The method according to the invention is for example implemented periodically to check the wear of the aircraft brake discs 1.

[0103] Thus, thanks to the invention, the wear measurement method makes it possible to evaluate the state of wear of the aircraft brake discs remotely on the basis of an image acquired from the wear indicator. The analysis of this image then makes it possible to quantify the state of wear of the aircraft brake discs by measuring at least one dimension associated with this wear indicator. This measurement is carried out on the basis of at least three reference points, which makes it possible to obtain a reliable measurement of the characteristics of the wear indicator.

[0104] Advantageously, the present invention does not require any external equipment (such as a ruler for example) to evaluate the wear measurement of the aircraft brake discs 1.

[0105] In addition, no material modifications shall be made to the aircraft brake to enable the wear condition of the aircraft brake discs to be assessed. No additional material costs are therefore incurred and the invention can be implemented on any aircraft.

[0106] Finally, thanks to the present invention, the state of wear of the aircraft brake discs can be determined without risk (i.e. without getting too close to the heat sink whose temperature is very high), in an automated and precise manner thanks to the marks identified on the wear indicator.

[0107] The present invention finds a particularly advantageous application for monitoring the wear of aircraft brakes. This is particularly useful for transmitting information to the user concerning the next replacement of the brake discs.

Claims

CLAIMS

1. Method for measuring the wear of the discs of an aircraft brake (1) provided with a wear indicator (6) mounted movably on a fixed part of the aircraft brake (1) and moving as the discs wear, the method comprising steps of: - acquisition of an image (Im) of a part of the aircraft brake discs (1), - identification of the wear indicator (6) in the acquired image (Im), - identification of at least three reference points (A1, B1, C2) on the wear indicator (6), and - determination of at least one measurement of wear of the aircraft brake discs (1) by determining at least one dimension (L, W) associated with the wear indicator (6) from the three reference points (A1, B1, C2) identified.

2. Method according to claim 1, in which, in the step of determining the wear measurement of the aircraft brake discs (1), provision is made to determine the width (W) and the length (L) of the wear indicator (6) from the three identified reference points (A1, B1, C2).

3. Method according to claim 1 or 2, in which there is provided, before the step of identifying the at least three reference points (A1, B1, C2), a step of delimiting a reduced part (Im1) of the acquired image (Im) and comprising the wear indicator (6), the identification of the at least three reference points (A1, B1, C2) being implemented from this reduced part (Im1) of the acquired image (Im).

4. Method according to any one of claims 1 to 3, in which the identification of the wear indicator (6) in the acquired image (Im) is implemented by means of an artificial neural network (NN1), the acquired image (Im) being provided as input to said artificial neural network (NN1) so as to obtain, as output from said artificial neural network (NN1), an area (Z1) of the acquired image (Im) on which the wear indicator (6) is identified.

5. Method according to claim 4, in which the identification of the at least three reference points (A1, B1, C2) is implemented by analyzing the area (Z1) of the acquired image (Im) obtained at the output of the artificial neural network (NN1).

6. The method of claim 4 or 5, wherein the artificial neural network (NN1) is a convolutional artificial neural network.

7. Method according to any one of claims 4 to 6, in which there is provided, prior to the step of acquiring the image, a step of training the artificial neural network (NN1) from a set of basic images.

8. Method according to any one of claims 1 to 7, wherein the identification of the at least three reference points (A1, B1, C2) on the wear indicator (6) is implemented by means of another artificial neural network (NN2), the acquired image (Im) in which the wear indicator (6) has been identified being provided as input to said other artificial neural network (NN2) so as to obtain, as output from said other artificial neural network (NN2), coordinates of the at least three reference points (A1, B1, C2).

9. The method of claim 8, wherein the other artificial neural network (NN2) is a convolutional artificial neural network.

10. Method according to claim 8 or 9 taken in dependence on claim 3, in which the reduced part (Im1) of the acquired image (Im) is provided as input to the other artificial neural network (NN2) so as to obtain, as output from said other artificial neural network (NN2), the coordinates of the at least three reference points (A1, B1, C2).

11. Method according to any one of claims 8 to 10, in which there is provided, prior to the step of acquiring the image (Im), a step of training the other artificial neural network (NN2) from another set of basic images.

12. Method according to any one of claims 1 to 11, in which, before the step of determining the wear measurement of the aircraft brake discs (1), a step of identifying at least one other reference point (C1, A2, B2, A3, B3, C3) is provided, the determination of the wear measurement of the aircraft brake discs (1) being implemented taking into account this other reference point (C1, A2, B2, A3, B3, C3).

13. Method according to any one of claims 1 to 12, wherein the at least three reference points (A1, B1, C2) correspond to visible ends of the wear indicator (6).

14. Device (10) for measuring the wear of the discs of an aircraft brake (1) provided with a wear indicator (6) mounted movably on a fixed part of the aircraft brake (1) and moving as the discs wear, the device (10) comprising: - an acquisition module (12) of an image (Im) of a part of the aircraft brake discs (1), - an identification module (14) of the wear indicator (6) in the acquired image (Im), - an identification module (16) of at least three reference points (A1, B1, C2) on the wear indicator (6), and - a module (18) for determining at least one measurement of wear of the aircraft brake discs (1) by determining at least one dimension associated with the wear indicator (6) from the three reference points (A1, B1, C2) identified.

15. A computer program comprising instructions executable by a processor (20) and designed to implement a method according to any one of claims 1 to 13 when these instructions are executed by the processor (20).

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