FR3028615A1 - METHOD FOR INSPECTING A PRODUCT SUCH AS A COMPONENT OF A TURBOJET NACELLE - Google Patents

Abstract

The present invention relates to a method of inspecting a product (25) such as a component of a turbojet engine nacelle or such as a turbojet nacelle. The method according to the invention is remarkable in that it comprises the following steps aimed at: defining an inspection zone (21); installing in said zone a robot (1) equipped with an image acquisition device (5) and connected to a computer programmed to process said images; - bringing the product (25) to inspect in said inspection zone (21); - acquire at least one image of the inspection area and check that it does not include any obstacle to the robot's movement; - Set, without contact between the robot and the product to be inspected, a mark of the robot according to the location of the product to inspect as positioned in the inspection area; - acquire at least one image of the product to be inspected; - transmit the acquired images to the computer; comparing at least one parameter specific to the product to be inspected to a corresponding parameter entered in a database; - establish a status of the inspected product.

Description

The present invention relates to a method of inspecting a product such as a component of a turbojet engine nacelle or such as a turbojet engine nacelle. An aircraft is moved by several propulsion units consisting of turbojets each housed in a nacelle. A nacelle generally has a tubular structure comprising an air inlet upstream of the turbojet engine, a median section intended to surround a fan of the turbojet engine, a downstream section capable of housing a thrust reverser device and intended to surround the combustion chamber of the engine. turbojet, and is generally terminated by an ejection nozzle whose output is located downstream of the turbojet engine. This nacelle is for example intended to house a turbofan engine capable of generating through the blades of the rotating fan a flow of hot air (also called primary flow), from the combustion chamber of the turbojet, and a cold air flow (secondary flow) flowing outside the turbojet through an annular channel, also called vein, formed between a shroud of the turbojet engine and an inner wall of the nacelle. The two air flows are ejected from the turbojet engine from the rear of the nacelle. The thrust reversal device is, during landing of the aircraft, intended to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine.

Generally, the nacelle manufacturers assemble each nacelle then send it to a motorist, who integrates the turbojet engine to the nacelle to form the propulsion unit. After assembly of the elements constituting the nacelle and before sending to the engine manufacturer, operators perform quality control of the assembled nacelle. This phase of control before sending, also called "final inspection phase" ("buy-off" in English terminology), is very important for the manufacturers of nacelles, for which the regulation is very strict in that it requires that each manufacturing defect be included in a nacelle tracking book. When the nacelle has a number of faults that exceed a certain value, defined by an aeronautical standard, the nacelle is not authorized to be installed on an aircraft, and the engine manufacturer rejects in this case the nacelle reception. In order to minimize the risk of such a situation occurring, the nacelle manufacturers have developed a method of inspection of the nacelle, prior to sending it to the engine manufacturer. This inspection process includes checking the following characteristics: presence / absence of parts, conformity of welds, length of fasteners, dimensional measurements of parts, etc. This process is performed manually by several operators who carry out the above-mentioned verifications. This manual control is not satisfactory. Indeed, this control has a very low rate of repeatability and a strong subjectivity. In addition, besides the ergonomic issues raised by this inspection phase, this operation is very expensive because of the presence of several operators. Finally, the risk of not detecting defects or detecting false defects is important, thus affecting the reliability of the prior art control method. The present invention aims at overcoming the disadvantages of the aforementioned prior art, and relates for this purpose to a method of inspecting a product such as a component of a turbojet engine nacelle or such as a turbojet engine nacelle. , 10 remarkable in that it includes the following steps to: - define an inspection area; - Install in said zone at least one mobile robot, equipped with a two-dimensional image acquisition device and / or three-dimensional and connected to a computer programmed to process said images; Bringing the product to be inspected into said inspection zone; acquiring at least one image of the inspection zone and verifying that said zone does not include any obstacle to moving the robot; setting, without contact between the robot and the product to be inspected, a mark of the robot according to the location of the product to be inspected as positioned in the inspection zone; acquiring at least one two-dimensional and / or three-dimensional image of the product to be inspected; - transmit the acquired images to the computer; comparing at least one parameter specific to the product to be inspected to a corresponding parameter entered in a database; - establish a status of the inspected product. Thus, thanks to the method according to the invention, the inspection of a product such as a turbojet engine nacelle component or such as a turbojet engine nacelle is, unlike the prior art, automated at least in part.

This advantageously makes it possible to substantially increase the repeatability rate of the inspection process and to reduce its subjectivity, a subjectivity due in the prior art to the intervention of an operator. Moreover, robotizing part of the inspection process considerably improves the ergonomics of the operator stations. The number of operators for carrying out the inspection method 35 according to the invention is furthermore substantially reduced compared to the prior art manual inspection methods, thereby reducing the cost of labor. associated with the inspection process, as well as the length of the inspection cycle of a product. Moreover, the inspection method according to the invention makes it possible to extract quality indicators of the product inspected, which makes it possible to monitor the manufacturing station or stations of said product.

Finally, the inspection method according to the invention is entirely made without contact between the product to be inspected and the robot, which makes it possible not to damage the product to be inspected. The step of the inspection method according to the invention for acquiring at least one image of the inspection zone and for verifying that said zone does not comprise any obstacle to the movement of the robot comprises the following steps intended to: robot at locations in the inspection area; - acquire at least one image of the inspection area; transmitting said at least one image to the computer; comparing said at least one transmitted image with an expected image stored in a database. Moreover, the step of setting, without contact between the robot and the product to be inspected, a robot mark according to the location of the product to be inspected as positioned in the inspection zone comprises the following steps aimed at: : 20 - move the robot to a calibration location; - acquire at least one two-dimensional or three-dimensional image of the product to be inspected; transmitting said at least one acquired image to the computer; identifying a known component or parameter of the product being inspected; extracting real coordinates of said component or parameter; comparing said real coordinates with theoretical coordinates of this component or parameter, entered in a database; define a reference specific to the robot so that it corresponds to that of the product to be inspected as it is positioned in the inspection zone. Other characteristics, objects and advantages of the present invention will appear on reading the following description and on examining the appended figures, all referring to the inspection method according to the invention and in which: FIG. 1 schematically illustrates a robot in the vicinity of a product to be inspected; FIG. 2 represents the path of a product to be inspected, alternately between its assembly line and the inspection zone; FIG. 3 is an explanatory view of the verification step of the inspection zone; FIG. 4 illustrates the parameterization step of the robot mark; - Figure 5 shows the movements of the robot to acquire images of the product to be inspected; Figure 6 is a flow chart of the inspection method of the invention. Throughout the figures, identical or similar references represent identical or similar organs or sets of members. The inspection method which is the subject of the present invention is preferably, but not exclusively, intended to be used in the aeronautical industry, more particularly during the assembly phase of the components constituting a turbojet nacelle, or when a final inspection of an already assembled nacelle. Of course, the inspection method according to the invention finds application in other industrial fields.

Referring to Figure 1 illustrating an example of mounting the control device for performing the control cycle of the method of the invention. This device comprises a robot 1, for example a six-axis robot well known to those skilled in the art. This robot 1 comprises an articulated arm 3. At one of the ends 3a of the arm 3 is mounted a device 5 for acquiring two-dimensional and / or three-dimensional images. The image acquisition device is further equipped with means for acquiring the topography of a part. This image acquisition device is removable in order to easily allow the mounting of a tool at the end of the arm, instead of the image acquisition device. A lighting device may also be installed on the robot 1, in order to optimize the quality of the images of the image acquisition device. The other end 3b of the arm 3 is for example mounted on a pivoting base 7 resting on a slide 9 which can move, for example in translation, along a rail 11. The robot 1 is connected to a computer executing scripts control unit, equipped with image processing software programmed to process the images transmitted by the image acquisition device. The computer also serves as an interface to the operator for visualizing the progress of a control cycle, displaying reports relating to this cycle, navigating through the selection menus and choosing the controls to be performed. According to the dimensions of the product to be inspected, the method according to the invention may require one or more robots 1. In the case where the product has significant dimensions, two robots 1 may be installed in such a way that they work together. At the same time, this increases accessibility and decreases cycle time. The product 13 to be inspected can also be mounted on a pivoting base 15 which can itself be mounted on a slideway 17 allowing it to move along a rail 19. Referring now to FIG. , the robot is in an inspection zone 21. This inspection zone 21 is defined by a protective immaterial enclosure. For this purpose, sensors are arranged around the inspection zone 21, and replace the protective grids usually used in the prior art. In case of unexpected introduction into the inspection zone 21 of a product other than the one to be inspected during a control cycle, these sensors allow the immediate termination of the control cycle.

The product to be inspected is initially on an assembly line 23 which can be arranged around the inspection zone 21. The product is, for example, moved into the assembly zone by a conveyor belt. In the example shown in Figure 2, it is desired to inspect the product in four different states A, B, C and D. When the product reaches the state Al of the assembly line 20, it is moved to the zone d inspection 21, for example by means of a conveyor belt. When it arrives in the inspection zone 21, the robot is at a standstill and in the retracted position, the starting position of a control cycle. This makes it possible to cross the light curtains safely and without triggering an emergency stop. When the product to be inspected is introduced into the inspection zone 21, the inspection cycle can start. Once the inspection cycle is completed, the inspected product is extracted from the inspection zone 21 and is moved to the zone A2 of the assembly line 23, via a conveyor belt. This procedure is repeated for each of steps B, C and D. Referring now to FIGS. 3 to 5, which schematically illustrate the steps of the control cycle according to the invention. According to a first variant, the control cycle can be started by the operator, who selects on a man-machine interface the type of product to be inspected (nacelle, nacelle subassembly, nacelle component, etc.). status of the product and the cycle it wants to launch. The man-machine interface, throughout the control cycle and in real time, makes it possible to visualize the progress of the inspection, to display the controls in progress and their processing or the controls already carried out and their control. result. Alternatively, the product to be inspected may carry a reference contained in an RFID chip or in a barcode. The reference may associate a product type, and the assembly step at which the product is located. According to this second variant, the starting parameters of the cycle are therefore pre-filled, unlike the first variant, and the operator only has to validate the start of the cycle. Regardless of the chosen launching mode of the control cycle, the control cycle comprises the following steps aimed at: checking that the control zone does not include any obstacle to the robot's movement; setting, without contact between the robot and the product to be inspected, a mark of the robot according to the location of the product to be inspected as positioned in the inspection zone; acquiring at least one two-dimensional and / or three-dimensional image of the product to be inspected; transmit the acquired images to the computer; comparing at least one parameter specific to the product to be inspected to a corresponding parameter entered in a database; - establish a status of the inspected product. The step of verifying that the inspection zone does not include any obstacle to moving the robot firstly consists in acquiring at least one image of the inspection zone by means of the two-dimensional image acquisition device and / or or three-dimensional. This device takes one or more photographs of the inspection area in which the product to be inspected 25 is positioned, without approaching it. These photographs are for example taken from the locations P1 and P2 of the inspection zone, shown in FIG. 3, locations located outside the product to be inspected but for example distinct from the original position Po of the robot. Of course, advantages of these locations may be provided depending on the dimensions of the product to be inspected. These photographs are transmitted to the computer, which verifies, through the image processing program, that the transmitted photographs are in accordance with the expected photographs recorded in a database. For this, the program performs a colorimetric comparison of the pixels between a transmitted photograph and an expected photograph. In case of detection of a color divergence between those transmitted and those of the expected photograph, the control cycle is automatically stopped, until an operator comes to notice the presence of a non-moving object. waited in the inspection area and relaunch the control cycle once the unexpected object has been removed from the inspection area. This advantageously makes it possible to prevent a foreign body from being positioned in the trajectories of the robot. Alternatively, in case of detection of a divergence of colors between those of the transmitted photograph and those of the expected photograph, the control cycle is automatically stopped, until an operator defines one or more parcels of the image area. inspection prohibited to the robot. The control cycle then comprises a step of setting, without contact between the robot and the product to be inspected, a marker of the robot according to the location of the product to be inspected as positioned in the inspection zone.

To do this, the robot 1 detects known points of the product, whose position is repeatable vis-à-vis the different control points. The robot, initially in position Po, moves to a calibration location Pr1, where it triggers a two-dimensional or three-dimensional image acquisition of the product to be inspected. The photograph is transmitted to the computer, which identifies via the image processing program a known component of the product being inspected, or a parameter associated with a known component of the product to be inspected. By way of example, a known component may consist of a ring, a rivet head, a thread, etc., and a parameter associated with a known component may be constituted by an angle, a bore depth, etc. The image processing program then extracts the actual coordinates of this known component or parameter and then compares them with the theoretical coordinates of that component or parameter entered in a database. The robot 1 then moves to the calibration locations Pr2 and Pr3 and performs the same acquisition and comparison as those performed for the calibration location Pr1. In the case where a component or parameter is not detected at one of the calibration locations, the computer controls the temporary stop of the control cycle in order to protect the product to be inspected against a possible collision related to a poor calibration. The operator can intervene at the man-machine interface to define the component or parameter not detected at the calibration location.

Once the acquisition and comparison steps thus carried out for the three calibration locations Pr1, Pr2 and Pr3, the robot returns to its original position 3028615 8 Po, and the robot specific reference is defined to correspond to to that of the product to be inspected as it is positioned in the inspection zone 21. It is of course possible to provide more calibration locations. By defining the mark according to the calibration locations Pr ', Pr2 and Pr3, the computer defines the actual positions of control points of the product to be inspected 25. In FIG. 4, the product to be inspected 25 comprises, by way of example, eight control points A1, A2, A3, B1, B2, C1, C2 and C3. This step makes it possible to clear the robot of the dispersions accumulated between the theoretical position of the product to be inspected and its actual position, but also to approximately position the product to be inspected in the inspection zone, contrary to the methods of the prior art. according to which an operator positions it accurately in the inspection area. By approximately positioning the product to be inspected in the inspection area, the duration of the control cycle is reduced. In addition, the fact of providing a setting of the mark of the robot according to that of the location of the product to be inspected, without contact between the robot and the product to be inspected, makes it possible not to damage the product being inspected. . This avoids, for example, that the paints of a product being inspected do not show chips. This arrangement of the inspection method according to the invention is very advantageous because this method can be applied to a product at the end of the assembly line just before sending it to the customer. Once the step of setting the robot mark according to the location of the product to be inspected as positioned in the inspection zone has been performed, the next step of the inspection cycle is to acquire at least one image two-dimensional and / or three-dimensional product to inspect, step illustrated in Figure 5 to which reference is now made. The robot 1 moves successively to the eight control points A1 to C3. The robot acquires one or more two-dimensional or three-dimensional images depending on the type of effector control, the product to be inspected at the control points considered. The acquired images are then transmitted to the computer.

Alternatively, the robot acquires a topography of the product to be inspected at the control points considered. More precisely, the robot is initially positioned at the point Po. The robot moves to the control point A1 according to the arrow 27, initiates the acquisition and, at the end of the acquisition, transmits the acquired image to the computer. While the computer is processing the received image, the robot then moves to the control point A2 according to the arrow 29. When the robot is at the control point A2, it checks that the computer has completed the process. process the acquisition made at checkpoint A1. When the computer tells the robot that the acquisition at point Al is complete, the robot acquires an image at checkpoint A2. This operation is repeated for all the control points, and the robot moves from one point to another of the control points A2 to C3 respectively according to the arrows 31 to 41. The movements of the robot are thus advantageously minimized, and the image acquisition cycle time of the product to be inspected is relatively short. In case of necessary retouching of an acquired image, for example that in point B2, the operator triggers a partial control on the group formed by the 10 points B1, B2. By activating the control of B2, the robot will move from Po to B1 according to the arrow 43, then move to the point B2, without acquiring an image of the product in point B1.After acquiring one or more images at the level of Control point B2, the robot returns to the original position Po according to the arrow 45. At the end of each acquisition, the computer receives the image or the topography that has been acquired. The computer's image processing program extracts requested parameters, such as dimensions, a color reading, and so on. each control point, and then compare them to expected parameters populated in a database. Depending on the result of the comparison, a product status at the checkpoint in question is established.

For example, when it is desired to establish whether the space between two pieces is satisfactory, the image processing program looks for the spacing extrema between the pieces, the average value and the standard deviation, and then verifies that these measured parameters do not exceed a predetermined acceptance threshold. If the thresholds are met at each control point of the product, the product receives an "OK" status. If one or more acceptance thresholds are exceeded, the product receives a "KO" status, and the image processing program highlights the value (s) concerned by this threshold exceeding, and informs the 'operator. An end of cycle report is then established by the computer. This report lists the checks performed and the status received by the inspected product.

When a control has been given "KO" status, it can be classified into two different categories. The first category corresponds to nonconformities that are noted, but which remain acceptable to the customer. For example, this type of non-compliance may be a deviation value of a part that causes aerodynamic loss. The second category corresponds to the controls for which the operator must define a procedure for correcting the detected fault. When a second category "KO" status is detected, the operator is required to repair the 3028615 10 or detected defects of the inspected product. For this purpose, the list of detected faults is for example transmitted to connected glasses, interactive. The operator who wears these glasses hands-free and can browse the defective product to decide on the procedure to follow for defects detected. When the second category defects are corrected, a control cycle such as that which is the object of the method according to the invention can be started again in order to inspect the repaired product. For a better understanding of the method according to the invention, FIG. 6 presents a logic diagram directly resulting from the steps of said method, detailed in FIGS. 1 to 5.

It goes without saying that the invention is not limited to the embodiments of the inspection method, described above merely as illustrative examples, but embraces all variants involving technical equivalents. described means as well as their combinations if they fall within the scope of the invention.

Claims (3)

REVENDICATIONS1. A method of inspecting a product (25) such as a component of a turbojet engine nacelle or a turbojet engine nacelle, characterized in that it comprises the following steps: inspection (21); - Install in said zone at least one mobile robot (1), equipped with a device (5) for acquiring two-dimensional images and / or three-dimensional and connected to a computer programmed to process said images; Bringing the product (25) to be inspected into said inspection zone (21); acquiring at least one image of the inspection zone (21) and verifying that said zone does not include any obstacle to the movement of the robot (1); setting, without contact between the robot (1) and the product (25) to be inspected, a mark of the robot according to the location of the product (25) to be inspected as positioned in the inspection zone (21) ; acquiring at least one two-dimensional and / or three-dimensional image of the product to be inspected; - transmit the acquired images to the computer; comparing at least one parameter specific to the product (25) to be inspected to a corresponding parameter entered in a database; - establish a status of the inspected product. 2. An inspection method according to claim 1, characterized in that the step of acquiring at least one image of the inspection zone and verifying that said zone comprises no obstacle to the movement of the robot comprises the following steps aiming to: - move the robot (1) to locations (P1, P2) of the inspection area (21); acquiring at least one image of the inspection zone (21); Transmitting said at least one image to the computer; comparing said at least one transmitted image with an expected image stored in a database. 3. Method according to one of claims 1 or 2, characterized in that the step to set, without contact between the robot and the product to be inspected, a robot locator 3028615 12 depending on the location of the product to inspect as positioned in the inspection area comprises the following steps to: - move the robot to a calibration location (Pr ', Pr2, Pr3); acquiring at least one two-dimensional or three-dimensional image of the product (25) to be inspected; transmitting said at least one acquired image to the computer; identifying a known component or parameter of the product being inspected; extracting real coordinates of said component or parameter; comparing said real coordinates with theoretical coordinates of this component or parameter, entered in a database; - Set a robot specific landmark so that it corresponds to that of the product (25) to inspect as positioned in the inspection area (21).