Camera polishing system for automotive vehicle structure

Abstract

The invention relates to a polishing system (10) for protruding asperities on a mechanical part (12), such as a motor vehicle structure. The polishing system comprises a receiving space (15) for the mechanical part, a first articulated arm (22) equipped with a polishing tool (24), and a control unit (16). The polishing system further comprises a second articulated arm (28) configured to be controlled by the control unit. The second articulated arm (28) includes vision means (30) capable of detecting a protruding asperity on the mechanical part. The control unit (16) is configured to control the first articulated arm (22) to polish the mechanical part (12) with the polishing tool (24) so ​​as to remove said asperity detected by said vision means. The invention also relates to a polishing method and a computer program. Figure to be published with the abstract: Figure 1

Description

Title of the invention: Camera-based polishing system for automotive vehicle structures

[0001] The invention relates to the surface control of parts, for example in the automotive field. More specifically, the invention relates to a system and a method for polishing a part. The invention also relates to a computer program.

[0002] A motor vehicle has a complex structure, or body. This structure comprises a plurality of stamped and welded sheet metal panels. Following the assembly of the body, the raw structure undergoes various finishing operations that contribute to the perceived quality of the motor vehicle. In order to guarantee this quality according to pre-established standards, the structure undergoes polishing operations to eliminate certain imperfections.

[0003] Polishing and sanding operations in automotive manufacturing have evolved from a manual process performed by an operator using polishing tools to automation using robots and rotary tools. This technique allows for the automatic removal of weld defects by polishing the surface along a predetermined path that covers all areas of the body. This improves the appearance and final finish of the vehicle while avoiding the arduous conditions of manual work.

[0004] During the automated welding process on a production line, material spatter is a common and random type of defect. This spatter occurs when the molten metal does not completely fuse with the base metal and is ejected outwards from the weld, leaving an accumulation of material near the weld point. The excess molten material and the resulting marks are then removed by polishing or sanding the metal surface with an automatic polishing tool attached to a robot. The polishing tool follows a path connecting the weld points.

[0005] Robot-assisted automated weld defect polishing systems are precise and uniform, thus improving the quality of the final finish. Furthermore, robots can operate in hazardous or difficult conditions, particularly in environments containing metallic dust. These robots therefore reduce safety costs. However, excessive polishing and grinding of weld defects can present several risks, such as excessive material removal. An excessive amount of material is removed, weakening the weld and / or the plates. This increases the risk of failure since the mechanical properties and characteristics of the weld can be altered.

[0006] Furthermore, excessive sanding and polishing can generate heat that may affect the metal structure and cause residual stresses. It can also create new defects such as scratches or imperfections on the weld surface.

[0007] However, the precision of retouching is limited. Indeed, the structure commonly has a coating whose thickness is on the order of a tenth of a millimeter. This coating is susceptible to being removed locally when polishing is too pronounced. Consequently, the structure is no longer effectively protected from asperities at the point of retouching.

[0008] There is a need to provide a solution minimizing at least one of these risks.

[0009] Document CN114310962A describes an intelligent robot communication control system for grinding and an associated method. The system includes a top-level computer, an IRB6700-200 type grinding robot, a control demonstrator, a floor-type belt sander, a clamping jaw, an air compressor, a three-dimensional laser scanner, and other visual image acquisition modules. The top-level computer serves as the master station, the demonstrator as the slave station, the top-level computer sends an instruction to the control demonstrator, and the demonstrator receives and sends the instruction to the grinding robot and the belt sander to grind a workpiece.The visual image acquisition module is used to perform feature recognition on the external surface of the polished part; determine a posture track and send the posture track to a higher-level computer. The actual position of the part to be polished is obtained from the position of a camera located at the rear end of the polishing robot.

[0010] Document CN109955122A and document CN209811886U describe fully automatic grinding systems based on computer vision. A system comprises a workpiece clamping platform, a grinding device, a computer vision imaging system, a higher computer control system, and a robot control cabinet. The grinding device includes an industrial robot mounted on one side of the workpiece clamping platform, and a grinding execution device used to grind the workpieces is mounted on the industrial robot. The computer vision imaging system is used to collect image data of the faces to be ground on the workpieces. The higher computer control system establishes a three-dimensional model of the faces to be ground based on the image data collected by the computer vision imaging system.

[0011] However, these systems are limited in terms of speed. Furthermore, each imaging system is exposed to projections during the polishing phases. In addition, the presence of the grinding device limits the field of vision by forming a physical mask that obscures certain defects.

[0012] The invention aims to address at least one of the problems or inconsistencies The invention aims to increase the speed of polishing and inspection of mechanical parts. It also aims to optimize the speed, wear of polishing tools, safety, and precision of refinishing a coated mechanical part, particularly a motor vehicle structure.

[0013] According to a first aspect, the invention proposes a system for polishing protruding asperities on a mechanical part; the polishing system comprising a mechanical part receiving space, a first articulated arm equipped with a polishing tool; a control unit; remarkable in that the polishing system further comprises a second articulated arm configured to be controlled by the control unit, the second articulated arm comprising vision means capable of detecting a protruding asperity on the mechanical part; the control unit being configured to control the first articulated arm in order to polish the mechanical part with the polishing tool so as to remove said asperity detected via said vision means.

[0014] It will be understood that the invention proposes a system for polishing a protruding asperity on a mechanical part; the polishing system comprising a space for receiving the mechanical part, a control unit for a first articulated arm equipped with a polishing tool and a second articulated arm with vision means capable of detecting a protruding asperity on the mechanical part; the control unit being configured to control the first articulated arm in order to polish the mechanical part with the polishing tool so as to abrade the asperity detected via said vision means.

[0015] Document CN111496580A describes a multi-machine cooperative processing system and method for a large-caliber aspheric optical element. The multi-machine cooperative processing system comprises a robot body, a robot body controller, a polishing tool, a workbench, a polishing fluid supply system, and a programming simulation test system. Through a control instruction, several robots can guide the polishing tool to polish a part along a planned path. However, polishing along the planned path does not allow for adaptation to production variations.

[0016] Preferably, the vision means are configured to estimate a roughness thickness; the control unit being configured to control the first articulated arm and the polishing tool according to said roughness thickness.

[0017] Preferably, the vision means are configured to be sensitive to light in the visible and infrared ranges.

[0018] Preferably, the second articulated arm includes a light source associated with the vision means.

[0019] Preferably, the polishing tool includes an abrasive disc and / or an abrasive brush.

[0020] Preferably, the vision means include a camera.

[0021] Preferably, the polishing system further comprises a third articulated arm identical to the second articulated arm.

[0022] Preferably, the receiving area includes a support suitable for receiving the mechanical part.

[0023] Preferably, the receiving area includes means for retaining the mechanical part.

[0024] Preferably, the mechanical part is metallic.

[0025] Preferably, the vision means are suitable for inspecting the mechanical part.

[0026] Preferably, the first articulated arm and the second articulated arm are arms articulated along at least five axes of mobility.

[0027] Preferably, the polishing system includes a user interface.

[0028] Preferably, the polishing tool comprises a diameter of at most 10 cm, more preferably of at most 5 cm.

[0029] Preferably, the vision means include an asperity recognition module based on reference images.

[0030] Preferably, the recognition module is configured to recognize an asperity according to a machine learning process.

[0031] According to another aspect, the invention proposes a method for polishing a protruding asperity on a mechanical part using a polishing system; remarkable in that the polishing system is in accordance with the invention, and in that the polishing method comprises the following steps: a) inspection of a surface of the mechanical part with the vision means of the second articulated arm; b) detection of a protruding asperity on said surface; c) polishing of the asperity with the polishing tool of the first articulated arm; then preferably, d) checking the surface at the location of the polishing of the asperity polished during step c) polishing.

[0032] Preferably, the polishing process includes a step e) estimating the wear of the polishing tool of the first articulated arm.

[0033] Preferably, the mechanical part comprises two metal elements fixed by a weld at the level of the asperity detected in step b) detection; preferably, the polishing process comprises a step f) emission of a weld anomaly signal when the detected asperity fulfills an anomaly criterion.

[0034] Preferably, the mechanical part is a motor vehicle structure.

[0035] Preferably, the structure comprises a coating forming said surface.

[0036] Preferably, the coating comprises zinc.

[0037] Preferably, the control method includes a step of determining rotation speed of the polishing tool and / or pressure applied by the polishing tool on the asperity detected in step b) detection.

[0038] According to another aspect, the invention proposes a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the polishing process according to the invention.

[0039] Preferably, the polishing process includes a step g) calculation of a trajectory of the polishing tool of the second articulated arm, said trajectory passing through the asperity detected in step b) detection.

[0040] Preferably, the computer is integrated into the control unit.

[0041] According to another aspect, the invention proposes a method for monitoring the wear of a polishing tool of a roughness polishing system; remarkable in that the polishing system is in accordance with the invention, and in that the method for monitoring the wear of the polishing tool comprises the steps: a) inspection of a surface of the mechanical part with the vision means of the second articulated arm; b) detection of a roughness protruding on said surface; c) polishing of the roughness with the polishing tool of the first articulated arm; e) estimation of the wear of the polishing tool of the first articulated arm.

[0042] According to another aspect, the invention proposes a computer program comprising instructions which, when the program is executed by a computer, lead the latter to implement the wear monitoring method according to the invention.

[0043] Each feature introduced by the expression "preferably" given in relation to one of the aspects of the invention applies to all other aspects of the invention.

[0044] The invention will be well understood and other aspects and advantages will become clear upon reading the following description, given with reference to the attached figures listed below.

[0045] Fig. 1 represents a polishing system according to the invention.

[0046] Figure 2 illustrates vision means and a polishing tool for analyzing and processing a rough surface of a mechanical part in a polishing system according to the invention.

[0047] Fig. 3 is a diagram of a polishing process according to the invention.

[0048] In the following description, the term "include" is synonymous with "include" and is not limiting in that it permits the presence of other elements in the polishing system or other steps in the polishing process to which it relates. It is understood that the term "include" includes the terms "consist of." The terms "external" and "internal" shall respectively refer to what is directed outward from the vehicle and inward from the vehicle.

[0049] In this description, the ranges of values ​​include the bounds that define them. limit.

[0050] In the present description, equality between values ​​is not to be understood in the strict sense insofar as each equality allows a variation of at most 10%, preferably at most 5%, more preferably at most 2%, between these values.

[0051] In this description, the technical characteristics are defined in the mounting configuration of the polishing system, unless otherwise explicitly stated.

[0052] Throughout the description, the different figures use the same reference signs to designate identical or similar entities.

[0053] Figure 1 represents a polishing system 10 for smoothing the roughness of a mechanical part 12. In this illustration, the mechanical part 12 is a structure 14 of a motor vehicle. The structure 14 defines the passenger compartment of the motor vehicle. It extends across the entire width of the motor vehicle. It can extend substantially along the entire length of the motor vehicle. The structure 14 has a length between 2 m and 5 m; preferably between 3 m and 4.5 m.

[0054] The polishing system 10 is intended for use in the automotive field. In particular, it meets constraints of speed and precision.

[0055] The polishing system 10 is suitable for polishing (non-visible) asperities protruding from the mechanical part 12. These asperities form raised areas. They form bumps. They create irregularities and defects on the surface of the mechanical part 12. They increase surface roughness and impair surface homogeneity, and therefore the perceived quality. The asperities have a length of at most 6 mm, preferably at most 2.0 mm, and more preferably at most 1.0 mm. The length is measured along the surface from which the asperity protrudes.

[0056] The polishing system 10 includes a receiving space 15. The receiving space 15 preferably includes a fixed support (not shown) for holding the mechanical part 12, which allows it to be held firmly in a precise position. According to an alternative embodiment of the invention, the polishing system includes a conveyor that moves the mechanical part to the receiving space.

[0057] The polishing system 10 includes a control unit 16. The control unit 16 controls the moving parts in the mechanical part 12, and in particular the entry and exit of the mechanical part 12. It is coupled to the actuators and sensors. The control unit 16 includes, for example, a human-machine interface 18, for example with a display screen and means for an operator to enter instructions.

[0058] The polishing system 10 comprises a first robot 20 with a first articulated arm 22 equipped with a polishing tool 24. The first robot 20 is controlled by the control unit 16. The first articulated arm 22, thanks to its polishing tool 24, is capable of reaching all surfaces of the mechanical part 12. The first articulated arm 22 is in the receiving space 15, or adjacent to the receiving space 15.

[0059] The polishing system 10 also includes a second robot 26 with a second articulated arm 28. The second articulated arm 28 is equipped with vision means 30. The vision means 30 are computer vision means, also called digital vision means. They include photosensitive sensors and are capable of acquiring at least one digital image of the mechanical part 12. The digital images are transmitted to the control unit 16, which processes them.

[0060] The vision means 30 contribute to the computer detection of protruding asperities on the mechanical part 12. The control unit 16 is configured to control the first robot 20 in order to polish the mechanical part with the polishing tool of the first articulated arm 22 so as to remove said asperity detected by said vision means 30.

[0061] Each robot is fixed in the receiving space 15, or mobile thanks to a mobile base. Each mobile base is capable of moving around the mechanical part 12. Each articulated arm comprises at least one mobile segment, preferably several mobile segments; for example three segments mobile relative to each other and relative to the optional base.

[0062] The arms are rotationally mobile and are moved by motors controlled by the control unit 16. Thus, the polishing tool 24 and the vision means 30 can scan all surfaces of the mechanical part 12. In the context of the motor vehicle structure, the polishing tool 24 and the vision means 30 can reach all or part of the internal surface of the motor vehicle structure 14. Each articulated arm comprises at least two axes of rotation, preferably at least three axes of rotation, more preferably at least four axes of rotation, and even more preferably at least five axes of rotation.

[0063] According to one option of the invention, the first articulated arm and the second articulated arm are arranged on the same robot. They are linked to the same base. They are mobile relative to each other.

[0064] Figure 2 shows a polishing tool 24 and vision means for a system of polishing 10 facing a mechanical part 12. The polishing system 10 can correspond to that presented in relation to [Fig.1]; just like the mechanical part 12.

[0065] The polishing tool 24 is at one free end of the first articulated arm 22. The vision means 30 are at one free end of the second articulated arm 28, for example at the last segment. They face a surface 32 of the mechanical part 12.

[0066] The vision means 30 are capable of identifying and detecting an asperity (not re presented) protruding on the mechanical part 12. The vision means 30 allow the detected asperity to be positioned. The positioning can be according to a reference frame specific to the mechanical part 12 or to the receiving space 15. The control unit 16 is adapted to control the first robot, in particular the first articulated arm 22, in order to polish the mechanical part 12 with the polishing tool 24 so as to remove the said asperity detected by the said vision means.

[0067] An asperity generally forms a bump with a thickness between 0.01 mm and 3 mm, preferably between 0.03 mm and 1 mm; more preferably between 0.2 mm and 0.5 mm. The thickness is measured perpendicular to the surface 32.

[0068] The vision means 30 are configured to estimate the thickness of a surface asperity. The surface asperity thickness is estimated statistically based on its width, or by means of two images taken from different viewing angles. The control unit 16 is configured to control the first articulated arm 22 according to said surface asperity thickness. It modulates at least: the polishing time, the rotation speed, and the pressure of the polishing tool 24, according to the surface asperity thickness.

[0069] The vision means 30 include a camera. The camera is, for example, a hyperspectral camera. They may include an infrared camera. The vision means 30 are configured to be sensitive to light in the visible and infrared ranges. Generally, the vision means 30 include a camera. The vision means 30 are sensitive to light with wavelengths between 700 nm and 2000 nm.

[0070] According to one option, the second articulated arm 28 includes a light source 34 associated with the vision means 30. The light source 34 may be circular. It may surround an optical axis of the vision means 30. The light source 34 is integral with the vision means 30. In the present embodiment, the light source 34 forms a ring; however, it may describe any other shape.

[0071] The polishing tool 24 comprises a rotating tool. The rotating tool is circular. The polishing tool 24 includes an abrasive disc and / or an abrasive brush. It may be cylindrical. The polishing tool 24 has a diameter of less than 10 cm, more preferably less than 5 cm. A limited diameter reduces the polished area and allows access to hidden and confined surfaces. Combined with the vision means 30, the radius allows for a more streamlined polished area and access to it despite the presence of physical obstacles.

[0072] According to an alternative or option of the invention, the polishing tool includes sandpaper.

[0073] The mechanical part 12 is metallic. It may be made of steel or aluminum. The mechanical part 12 comprises at least two metallic elements fixed by welding at the level of the asperity. Preferably, the mechanical part 12 comprises at least dozens of metal elements welded together. They may be welded using electric spot welds. The metal elements may be sheet metal. The sheet metal has thicknesses between 0.5 mm and 1.5 mm, preferably between 0.65 mm and 0.85 mm.

[0074] The mechanical part 12 includes a coating forming said surface 32. The surface 32 is preferably a curved surface. Optionally, it forms a rebate. The coating may be zinc. It may correspond to a galvanic layer. For example, after welding, the metal elements are immersed in a bath of molten zinc.

[0075] According to one option of the invention, the polishing system further comprises a third articulated arm (not shown) identical to the second articulated arm. The third articulated arm allows for a visual inspection of the mechanical part after polishing. The third articulated arm is, for example, specific to a third robot. This multitude of articulated arms optimizes production rates, rectification, and inspection.

[0076] The invention makes it possible to physically decouple visual inspection from polishing and to perform these operations simultaneously. Furthermore, depending on the mechanical parts and their typical surface irregularities, visual inspection may be slower than polishing, or vice versa. Thus, the two-arm configuration limits the impact of differences in operating times between the vision system and the polishing tool.

[0077] The control unit 16 includes a processor 36 and a memory 38. The human-machine interface 18 is connected to the first robot and the second robot via the control unit 16.

[0078] The processor 36 may include one or more programmable electronic microprocessors or microcontrollers. Furthermore, the processor 36 may include a central processing unit (CPU), memory (in addition to or as separate memory as illustrated by reference number 38), and an input / output (I / O) interface through which the processor 36 can receive a plurality of input signals. Such an I / O interface is also configured to generate a plurality of output signals, including, but not limited to, those used to control and / or provide data to the display of the human-machine interface 18.

[0079] The memory 38 is intended for storing data and instructions or code (i.e., software) for and readable and / or writable by the processor 36. The memory 38 may include various forms of non-volatile (i.e., non-transient) memory. Non-volatile memory includes flash memory or read-only memory (ROM), any type of programmable read-only memory (e.g., PROM, EPROM, EEPROM). The memory 38 optionally includes volatile memory, including random access memory (RAM), static random access memory (SRAM), dynamic random access memory (DRAM), and synchronous dynamic random access memory (SDRAM). According to the invention, the memory may be internal to the processor 36; or alternatively, form a separate component.

[0080] Figure 3 shows a diagram of a roughness polishing process with a polishing system. The polishing system and / or the mechanical part may correspond to the one, one, or ones shown in relation to one of Figures 1 to 2.

[0081] The polishing process comprises the following steps:

[0082] a) inspection 100 of a surface of the mechanical part with the vision means of the second articulated arm;

[0083] b) detection 102 of a protruding asperity on the surface;

[0084] c) polishing 104 of the asperity with the polishing tool of the first articulated arm; and preferably,

[0085] d) control 106 of the polished surface at the point of polishing the asperity detected during step b) detection 102;

[0086] e) wear estimate 108 of the polishing tool of the first articulated arm;

[0087] f) emission 110 of a weld anomaly signal when the detected asperity fulfills an anomaly criterion;

[0088] g) calculation 112 of a trajectory of the polishing tool of the first articulated arm, said trajectory passing through the asperity detected in step b) detection 102;

[0089] h) determination 114 of rotation speed and / or pressure of the polishing tool.

[0090] The mechanical part comprises at least two metal elements joined by a weld. During the welding operation, their attachment area is likely to be splattered with droplets of molten metal. These droplets then form raised asperities. When the weld is an electric spot weld, the weld area can become dented and form a raised asperity. Such asperities are detected during step b) detection 102.

[0091] The mechanical part preferably comprises a coating forming said surface. During step c) polishing 104, the asperity is removed by stopping before reaching the coating on the surface. Thus, the polishing operation is limited in thickness, in addition to being limited in the extent of the mechanical part. It does not thin the coating around the asperity. This preserves the coating and the physical integrity of the mechanical part so as not to weaken it. This is relevant in the automotive field since the thickness of sheet metal is optimized according to strength and mass. Excessive polishing can weaken the structure. Where necessary, limiting polishing preserves the mechanical strength of the welds.

[0092] According to an alternative embodiment of the invention, the asperity comprises a burr or a drip, or a bubble. Each of these imperfections creates a defect that remains visible, especially after the application of one or more coats of paint and varnish, as is generally the case on a car body. A burr can result from a sheet metal cutting step. A run can be a zinc drip, for example, during treatment in a bath. These detract from the perceived quality.

[0093] Step b) detection 102 is performed using an artificial intelligence algorithm, specifically a deep learning algorithm. Such an algorithm is generally referred to by the English term "Deep Learning". The deep learning algorithm detects weld defects, bumps, peaks, and other artifacts specific to the surface of the mechanical part. The deep learning algorithm detects these features in the images from the vision systems and predicts the defects, their size, type, and severity. It implements a convolutional neural network, generally referred to by the acronym "CNN".

[0094] The input data for the convolutional neural network consists of images captured by vision systems. The images can be resized, filtered, reoriented, and cropped. The output data is a series of regions of interest found in these images, each with metadata corresponding to the size, type, and thickness of the asperity. The algorithm is trained using a supervised or unsupervised method. It is trained with defect-free images and images with defects labeled according to the type of defect. The deep learning algorithm is trained until a deep learning model is achieved with a reliability of at least 95%, preferably at least 99%.

[0095] Step e) estimation 108 is performed by comparing the images obtained during step a) inspection 100 and step d) control 106. When the roughness persists despite a predefined polishing time, tool wear is identified. According to an alternative of the invention, step e) estimation 108 is performed by calculating the usage time of the polishing tool.

[0096] In step f) emission 110, if the asperity has a thickness and / or length exceeding a predefined threshold, the anomaly signal is emitted. The signal can be emitted if the asperity has a certain shape or a given color.

[0097] For step f) emission 110, a machine learning algorithm is implemented. Such a solution is generally designated by the acronym "ML," which corresponds to the Anglo-Saxon expression "Machine Learning." The purpose of this machine learning algorithm is to correlate the results of the robotic polishing tool with upstream manufacturing processes, such as a welding assembly process. The objective is to find the causes of the occurrence of defects. For example, if the defects are caused by a misalignment of the robots welding, this machine learning algorithm highlights a correlation of data that could indicate such causality.

[0098] The machine learning algorithm comprises a neural network with several hidden layers. The neural network can be fully connected or partially connected. The mathematical formulas for connecting the neurons include sigmoid-type activation functions. Other activation functions are considered. The network architecture is, for example, a forward-propagating neural network.

[0099] The input data includes all process data from previous manufacturing steps, such as cycle times, welding parameters, references, and temperatures. Other data are possible. Welding parameters include current, electrical quantities, and pressure.

[0100] The output data includes a series of correlation rules linking the input data and the defective parts. The machine learning algorithm is trained by creating a dataset with previous occurrences in which the data are labeled. The training data includes measured data and optionally simulation data.

[0101] Step d) inspection 106 can be carried out by the second articulated arm or by the optional third articulated arm. If the result does not meet the quality criteria, the process repeats step c) polishing 104.

[0102] The invention comprises the combination of all the embodiments illustrated by all the figures.

Claims

Demands

1. Polishing system (10) for protruding asperities on a mechanical part (12); the polishing system (10) comprising a receiving space (15) for the mechanical part (12), a first articulated arm (22) equipped with a polishing tool (24); a control unit (16); characterized in that the polishing system (10) further comprises a second articulated arm (28) configured to be controlled by the control unit (16), the second articulated arm (28) comprising vision means (30) capable of detecting a protruding asperity on the mechanical part (12); the control unit (16) being configured to control the first articulated arm (22) in order to polish the mechanical part (12) with the polishing tool (24) so ​​as to remove said asperity detected via said vision means (30).

2. Polishing system (10) according to claim 1, characterized in that the vision means (30) are configured to estimate a roughness thickness; the control unit (16) being configured to control the first articulated arm (22) and the polishing tool (24) as a function of said roughness thickness.

3. Polishing system (10) according to any one of claims 1 to 2, characterized in that the vision means (30) are configured to be sensitive to light in the visible and infrared ranges; preferably, the second articulated arm (28) comprises a light source (34) associated with the vision means (30).

4. Polishing system (10) according to any one of claims 1 to 3, characterized in that the polishing tool (24) comprises an abrasive disc and / or an abrasive brush; preferably, the vision means (30) comprise a camera.

5. Polishing system (10) according to any one of claims 1 to 4, characterized in that the polishing system (10) further comprises a third articulated arm identical to the second articulated arm (28).

6. A method for polishing a protruding asperity on a mechanical part (12) using a polishing system (10); characterized in that the polishing system (10) conforms to any one of claims 1 to 5, and in that the polishing method comprises the following steps: • a) inspection (100) of a surface (32) of the mechanical part (12) with the vision means (30) of the second articulated arm (28); • b) detection (102) of a protruding asperity on said surface (32); • c) polishing (104) of the asperity with the polishing tool (24) of the first articulated arm (22); then preferably, • d) inspection (106) of the surface (32) at the location of the polishing of the asperity polished during step c) polishing (104).

7. Polishing method according to claim 6, characterized in that the polishing method includes a step e) estimation (108) of wear of the polishing tool (24) of the first articulated arm (22).

8. A polishing method according to any one of claims 6 to 7, characterized in that the mechanical part (12) comprises two metal elements fixed by a weld at the level of the asperity detected in step b) detection (102); preferably, the polishing method comprises a step f) emission (110) of a weld anomaly signal when the detected asperity fulfills an anomaly criterion.

9. A polishing method according to any one of claims 6 to 8, characterized in that the mechanical part (12) is a motor vehicle structure (14); preferably, the structure (14) comprises a coating forming said surface (32).

10. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the polishing process according to any one of claims 6 to 9; preferably, the polishing process comprises a step g) calculation (112) of a trajectory of the polishing tool (24) of the second articulated arm (28), said trajectory passing through the asperity detected in step b) detection (102).

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