INSPECTION METHOD OF A JOINT TAPE OF AN INDUSTRIAL WORKPIECE, AND SYSTEM FOR IMPLEMENTING THIS METHOD

Description

Technical field

[0001] The present invention relates to the general technical field of the manufacture and / or assembly of industrial parts.

[0002] The invention relates more particularly to the control of the deposition of a material joint in the context of a manufacturing process for industrial assemblies. Such a deposition of material, for example in the form of a bead, makes it possible to create a seal and / or a mechanical connection between said parts at the joint of two parts. It is therefore imperative to place these beads of material at precise locations on a part and to do so repeatedly. It is indeed important to obtain the same reliability in the seal or in the assembly for a set of parts manufactured in series.

[0003] The invention therefore relates more particularly to the control of material beads once deposited on the part. In this case, these are deposits of smoothed or unsmoothed material joints.

[0004] The invention therefore finds its application in particular in the field of the automobile industry and more precisely in the assembly of body parts of a vehicle. Other applications in other technical fields such as aeronautics, the naval industry or others are also concerned by the present invention.

[0005] The term "part" should be understood in the broad sense, i.e. encompassing a single part, an assembly of parts or, for example, a vehicle body or a body part.

[0006] For example, document FR 2741438 discloses a device and method for dimensional control of a bead of material deposited on a support. The method described in this document is based on the use of a camera and suitable software to detect dimensional defects in the bead. The method and device described make it possible both to deposit the bead and to visually control its dimensions during the same operation. The implementation of such a method is relatively complex and has a number of drawbacks. Document FR 2817618 discloses another device and method for controlling physical parameters relating to a bead of material deposited on an industrial part.

[0007] Indeed, the simultaneous deposition of the bead and its dimensional control substantially reduces the performance of the control device. The camera must follow the movement of the device for depositing the bead, which, in a certain number of cases, does not put it in an ideal position to visually check the quality of the bead. The speed of movement of the camera is also limited by the speed of movement of the device for depositing the bead. In addition, the tool used to carry out these manipulations becomes very complex to produce.

[0008] The object of the present invention therefore aims to propose a new control method overcoming the drawbacks of the prior art and consequently freeing itself from all the constraints linked to the operations of laying a cord on a support.

[0009] Another object of the present invention is to provide a new control system making it possible to implement the control method and whose reliability is improved.

[0010] The objects assigned to the present invention are achieved using a method for controlling physical parameters relating to at least one bead of material deposited on an industrial part according to claim 1.

[0011] Within the scope of the invention, the bead of material deposited on the part may be smoothed or not smoothed.

[0012] According to an example of implementation, the control method consists of initiating corrective action instructions concerning the laying of the bead and / or concerning the control of the relative movement between the part and the vision machine.

[0013] According to an exemplary implementation, the control method consists of holding the part comprising the bead in a fixed position and placing the vision machine on the head of a robotic arm whose movement is automatically controlled to cause said bead to pass in front of the vision machine.

[0014] According to another example of implementation, the method consists of placing the part comprising the cord on a mobile support of the swing type, the movement of which is automatically controlled to move said cord past the fixed vision machine.

[0015] According to an exemplary implementation, the method comprises using the configuration computer to define for each image of the cord, an image relating to an ideal cord and generating suitable corrective parameters.

[0016] According to the invention, the method consists of realigning the image taken dynamically with respect to a reference image in order to be able to analyze the joint hidden by the cord and detect possible positioning defects of said cord with respect to said joint.

[0017] This reference image is stored in a reference database, which is built using a learning method.

[0018] Furthermore, the control process also allows, thanks to continuous learning, for example for a series of theoretically identical parts, to compensate for dimensional drifts of the parts and drifts in the relative movement between the parts and the vision machine.

[0019] At least one fixed reference mark should be used for each area to be inspected. For example, an assembly or fitting of two parts will have two areas and will require the use of at least two fixed marks, one for each area. A larger number of fixed marks will improve inspection accuracy.

[0020] According to an example of implementation, the control method consists of using three fixed markers.

[0021] According to an exemplary implementation, the control method consists of determining the fixed reference mark(s), determining an offset of the part relative to a previous reference image by estimating the displacement of the fixed reference marks relative to the fixed reference marks on the previous reference image and repositioning the optimal path of the joint to be covered on the part to be controlled.

[0022] According to an exemplary implementation, the control method consists of estimating the offset of the part by calculation, using a triangulation registration algorithm or an optimal calculation registration algorithm.

[0023] According to an exemplary implementation, the method consists of defining, for the bead, control segments, each of which is delimited according to its longitudinal extension by two end points, said end points being located relative to at least one fixed reference mark of the part, said segments being controlled one after the other with the vision machine or simultaneously with several vision machines.

[0024] According to an exemplary implementation, the method consists of choosing from among the parameters to be controlled, specific control parameters for each cord segment.

[0025] According to an example of implementation, the control method consists of viewing on the display tool the images of the bead deposited on the part as well as a materialization of the ideal position of said bead on each image.

[0026] According to an exemplary implementation, the control method comprises using a program for exchanging information between the vision head and the robotic arm and / or between the vision head and the configuration computer.

[0027] According to an example of implementation, the control method is implemented for parts intended for the automotive industry.

[0028] The objects assigned to the present invention are also achieved using a control system comprising a system for controlling a bead of material deposited on a part according to claim 14.

[0029] According to an exemplary embodiment, the control system comprises an additional database, such as a remote server, for example, to generate and provide corrective data or instructions.

[0030] According to an exemplary embodiment of the control system, the vision head comprises a digital camera, a ring light located around the camera and two projectors arranged at the periphery of the ring light with an angular separation of 90°.

[0031] According to an exemplary embodiment, the handling system comprises a robotic arm carrying the vision head.

[0032] According to another exemplary embodiment, the handling system comprises a mobile cradle on which the part carrying the cord is fixed.

[0033] The objects assigned to the present invention are also achieved by means of a computer program comprising program code instructions recorded on a computer-readable medium for implementing the steps of the control method presented above, when said program operates on a computer.

[0034] The control method according to the invention has the enormous advantage of being able to implement continuous learning in order to define an ideal cord in its shape, its aesthetics, its dimensions and its positioning.

[0035] Such learning also makes it possible to refine the necessary parameters based on the images read by the vision machine to get as close as possible to such an ideal bead. The nature and amplitude of the defects detected by the vision machine and the processing and analysis algorithms can thus make it possible to generate corrective instructions as the number of parts inspected increases.

[0036] Another advantage of the method according to the invention lies in its ability to anticipate a certain number of drifts, for example in the positioning of the bead linked to a drift in the positioning of the part relative to the tool for removing said bead. It is thus possible to know in advance or more precisely to quantify a dimensional or positional deviation after a given number of parts have been checked.

[0037] The high level of precision achieved, thanks to the algorithms and image processing software, therefore allows for a substantial improvement in the quality of the inspection and its reliability. In addition, any correction instructions generated and transmitted to the bead laying device allow for an improvement in the precision of its positioning on the one hand, as well as the shape and aesthetics of the bead, which significantly reduces the number of defective parts that the operator cannot validate and which must therefore be reconditioned.

[0038] Another advantage of the inspection method according to the invention lies in its flexibility of implementation. Indeed, the inspection method can be implemented either with a vision machine constituting the head of a robotic arm, or with a fixed vision machine in front of which a part mounted on a mobile swing passes.

[0039] Another remarkable advantage of the inspection method according to the invention lies in the dynamic recalibration of the image relative to the vehicle or the part, which makes it possible to precisely and repeatedly determine the location of the joint between two sheets covered by the bead. Indeed, the joint of the part to be inspected is normally covered by the joint deposited with material. This joint cannot therefore be read or identified by the vision head and since its positioning can vary from one part to another, it is thanks to the inspection method according to the invention that the position of said joint is precisely determined, even if it is not visible on the image read by a camera. The joint is then materialized by a line on the image and the position of the bead of material relative to this line can then be evaluated.

[0040] Image recalibration thus makes it possible to compensate for natural defects or wear and tear in the system and the robot.

[0041] The process and the implementation system thus remarkably make it possible to achieve excellent image registration precision of up to one micrometer. Brief description of the figures

[0042] Other characteristics and advantages of the invention will appear on reading the detailed description which follows, a description made with reference to the appended drawings, illustrative and non-limiting, in which: there figure 1 is a schematic representation illustrating an exemplary embodiment of a control system in accordance with the invention, the figure 2 is an illustration of an exemplary embodiment of a robot comprising a vision machine of a control system in accordance with the invention, the figure 3 is a schematic representation of an example of implementation of the method according to the invention, and the figures 4 to 6are examples of images generated by the control system according to the invention. Detailed description of the invention

[0043] In the following, elements shown in several figures, which are structurally and functionally identical, have the same numerical or alphanumeric references.

[0044] There figure 1 is a schematic representation illustrating an exemplary embodiment of a control system in accordance with the invention, which makes it possible to control a bead of material deposited on an industrial part, so as to verify the acceptability of dimensional parameters, shape or aesthetic parameters and / or positioning parameters.

[0045] The control system comprises at least one vision machine 1 comprising a vision head 2 in which software and analysis, processing and control algorithms are loaded, as well as a specific database 3 for storing the results, in particular images and values ​​of measured or calculated parameters.

[0046] The Vision Head 2, for example, runs on the Linux Ubuntu operating system on an NVIDIA Jetson TX1 card, which is ideally suited for image-based computing.

[0047] The specific database 3 is advantageously a Mysql bank.

[0048] The control system also comprises a handling system for enabling relative movement between the vision head 2 and the part. The control system also comprises a control unit 4 for controlling the handling system and generating data relating to the relative movement between the vision head 2 and the part carrying the bead of material.

[0049] The control system also comprises a configuration computer 5 for configuring the vision head 2 from data relating to the relative movement. These data relating to the relative movement are transmitted by the control unit 4 to the configuration computer 5.

[0050] The configuration computer 5 performs several functions, namely: configure the vision head 2, control a robot, control the vision head 2, save the configurations of the different vehicles or parts, view the results corresponding to each vehicle or part.

[0051] The control system advantageously comprises at least one display tool 6 of the touch tablet type, connected to the specific database 3. The display tool 6 makes it possible on the one hand to visualize the progress of the control operations and on the other hand to display the images of the bead of material taken by the vision head 2, in particular by identifying possible defects on said images.

[0052] The control system can be connected to a complementary database, such as a remote server or other data server. The latter can then retrieve the analysis data from each car to perform a preventive analysis of drifts and the corrections to be made.

[0053] There figure 2is an illustration of an exemplary embodiment of a handling system comprising the vision machine 1 of the control system. In this exemplary embodiment the handling system comprises a robotic arm 8 carrying the vision head 2. The robotic arm 8 is connected, by any known means, to the control unit 4.

[0054] According to another exemplary embodiment, the handling system comprises a mobile nacelle, on which the part carrying the cord of materials is fixed. In this case, the control unit 4 controls the movements of the nacelle so as to cause the cord of materials to pass in front of the vision head 2.

[0055] The vision head 2 comprises a digital camera 9 as well as an annular lighting 10 of the EFFI-RING type, located around said digital camera 9.

[0056] The vision head 2 also comprises two projectors 11 and 12 arranged at the periphery of the annular lighting 10 and having an angular separation of 90° from each other. The projectors 11 and 12 are advantageously EFFI-LASE structured LED projectors, making it possible to project lines and mounted at right angles to each other on the vision head 2. These projectors 11 and 12 are automatically oriented by means of specific algorithms. These projectors 11 and 12 thus make it possible to calculate the height of the deposited beads.

[0057] There figure 3 is a schematic representation of an example of implementation of the method according to the invention. The control unit 4 makes it possible to define the trajectory of the vision head 2. This trajectory corresponds to the trajectory for laying the bead of material and the corresponding instructions are therefore transmitted to the handling system.

[0058] The vision machine 1 thus makes it possible to acquire images of the bead of material deposited on the part and to store them after analysis using suitable algorithms in the specific database 3. The display tool 6 then makes it possible to read and display the results coming from the vision head 2 and stored in the specific database 3. The operator can also, via the display tool 6, modify the results stored in the specific database 3.

[0059] The control system thus makes it possible to implement the control method described in more detail below. The method for controlling physical parameters relating to at least one bead of material deposited on an industrial part comprises a certain number of steps listed below.

[0060] The cord is for example unsmoothed or smoothed using a manual, semi-automated or automated smoothing operation.

[0061] The method for controlling physical parameters relating to at least one bead of material deposited on an industrial part, said bead being intended to cover a joint, comprises a set of steps detailed below.

[0062] Step a) consists of defining the physical parameters to be controlled to detect defects in the cord, namely a cord sealing defect, a cord dimensional defect or a cord shape defect.

[0063] Step b) consists of choosing at least one fixed reference point, also called “top”, on the part to define the ideal location of the bead on the part in relation to the fixed reference point(s).

[0064] Step c) consists of using a movement device to generate a relative movement between, on the one hand, the part on which the bead is deposited and, on the other hand, at least one vision machine.

[0065] Step d) consists of using the vision machine to illuminate the cord, read and record a succession of images of the cord.

[0066] Step e) consists of using a configuration computer on which at least one configuration program is running to configure the vision machine and the motion device.

[0067] Step f) is to use a vision machine-specific database to record data from the vision head or supplied to the vision head.

[0068] Step g) consists of using a tablet-type display tool connected to the specific database via a communication system and allowing an operator to follow the progress of the control operations, almost in real time or delayed.

[0069] Step h) consists of comparing the read and recorded images of the cord with ideal images using algorithms loaded into the vision machine to detect defects in the cord.

[0070] Step i) consists of identifying and displaying the cord defects on the display tool and validating or not validating said defects.

[0071] Step j) consists of transmitting the detected, validated or non-validated defects to the specific database.

[0072] According to an example of implementation, the control method consists of initiating corrective action instructions concerning the laying of the bead and / or concerning the control of the relative movement between the part and the vision machine.

[0073] According to an example of implementation, the method consists of placing the part comprising the cord on a mobile support of the swing type, the movement of which is automatically controlled to move said cord past the fixed vision machine.

[0074] According to another example of implementation, the control method consists of maintaining the part comprising the bead in a fixed position and placing the vision machine on the head of a robotic arm 8 whose movement is automatically controlled to cause said bead to pass in front of the vision machine.

[0075] According to an exemplary implementation, the method consists of using the configuration computer 5 to define for each image of the cord, an image relating to an ideal cord and generating suitable corrective image registration parameters.

[0076] According to an exemplary implementation, the method consists of realigning the image taken dynamically with respect to a reference image in order to be able to analyze the joint hidden by the cord and detect possible positioning defects of said cord with respect to said joint.

[0077] This reference image is recorded in the specific database 3, in the form of reference data, said reference image being constructed from a learning mode.

[0078] Furthermore, the control process also allows, thanks to continuous learning, for example for a series of theoretically identical parts, to compensate for dimensional drifts of the parts and drifts in the relative movement between the parts and the vision machine.

[0079] According to an exemplary implementation, the method consists in defining control segments for the bead, each of which is delimited according to its longitudinal extension by two end points, said end points being located relative to at least one fixed reference mark of the part. The segments are controlled one after the other with the vision machine or simultaneously with several vision machines.

[0080] According to an exemplary implementation, the method consists of choosing from among the parameters to be controlled, specific control parameters for each cord segment.

[0081] According to an exemplary implementation, the control method consists of viewing on the display tool 6, the images of the bead deposited on the part as well as a materialization of the ideal position of said bead on each image.

[0082] According to an exemplary implementation, the control method consists of using a program for exchanging information between the vision head 2 and the robotic arm 8 and / or between the vision head and the configuration computer 5.

[0083] At least one fixed reference mark should be used for each area to be inspected. Thus, an assembly or fitting of two parts will have two areas and will require the use of at least two fixed reference marks 1b, namely one for each area. A greater number of fixed reference marks will improve inspection accuracy.

[0084] According to the invention, the control method consists of determining the fixed reference mark(s), determining an offset of the part relative to a previous reference image by estimating the displacement of the fixed reference marks relative to the fixed reference marks on the previous reference image and repositioning the optimal path of the joint to be covered on the part to be controlled.

[0085] According to an exemplary implementation, the control method consists of estimating the offset of the part by calculation, using a triangulation registration algorithm or an optimal calculation registration algorithm.

[0086] The control process thus makes it possible to recalibrate, by calculation, the real position of the joint on an image of the deposited bead.

[0087] THE figures 4 to 6 are examples of images generated by the control system according to the invention,

[0088] The control method according to the invention thus makes it possible to view on the display tool 6 images of the bead of materials deposited on the part 1a. The vision machine 1, thanks to the vision head 2, makes it possible on the one hand to restore an image of the bead by viewing as shown for example in figure 4a portion A identifying the position of the joint where the bead should be placed. The image obtained through the control process also allows a portion B to be displayed which indicates a width that is too large. The bead should therefore be smoothed at this location.

[0089] The image also makes it possible to identify a portion C corresponding to an absence of cord, namely a clear defect that should be detected, analyzed and treated. Advantageously, portion C is a line of a different color extending along the joint. Part 1a illustrated in figure 4 also has holes 1b, used as fixed geometric markers 1b, for the control system.

[0090] There Figure 5 illustrates for example a cord presenting a thickness or diameter defect on a section D. The joint is identified for example by a color different from that relating to an absence of cord. (cf figure 4). The portion thus presenting a dimensional defect is identified by the reference D on the Figure 5 .

[0091] In the example shown in figure 6 the image illustrating the bead deposited on part 1a thus easily allows the operator to identify the position of the joint in an area A where said joint is correctly covered by the bead of material. The latter also has a portion D with an aesthetic defect, a portion E with an area that is too wide, as well as a portion C without a bead and resulting from a smoothing defect.

[0092] The invention also relates to a computer program product comprising program code instructions, recorded on a computer-readable medium for implementing the steps of the control method according to the invention, when said program operates on a computer.

[0093] For example, Vision Head 2 has several programs written in C++.

[0094] A first program allows the digital camera 9 and the lighting 10, 11, 12 to be controlled and recovers the images on precise tops corresponding to reference points on the vehicle or on the part 1a to provide the images of the cord segments.

[0095] Another program allows from the images: to calculate the registration of the images using a registration algorithm, to detect the presence of material (for example putty) using a material detection, centering and width algorithm, to measure the height of the bead using a relief algorithm.

[0096] Obviously, the invention is not limited to the preferred embodiment described above and shown in the various figures, and those skilled in the art can make numerous modifications and imagine other variants. Thus, a described technical characteristic can be replaced by an equivalent technical characteristic or an implementation step can be replaced by an equivalent step, without departing from the scope or framework of the invention defined by the claims.

Claims

1. Method for checking physical parameters relating to at least one bead of material deposited on an industrial part (1a) and intended to cover a joint (1c), said method comprising the following steps: a) defining the physical parameters to be checked to detect one or more defects of the bead of material, i.e., a sealing defect, a dimensional defect or a shape defect, b) selecting one or more fixed reference points (1b) on the part (1a) to define an ideal position of the bead of material with respect to these fixed reference points (1b), c) using a handling system to generate a relative movement of the part (1a) and of at least one vision machine comprising a vision head (2), d) using the vision machine to illuminate the bead of material and reading and recording a sequence of images of the bead of material, e) using a computer (5) on which at least one configuration program runs to configure the vision machine and the handling system, f) using a specific database (3) of the vision machine to store therein data from the vision head (2) or provided to this vision head (2), g) using a display tool of the tablet type, connected to the specific database (3) via a communication system, to allow an operator to follow the progress of checking operations, almost in real time or in delayed mode, h) comparing the acquired images of the bead of material with ideal images using algorithms of the vision machine to detect defects of the bead of material therein, i) identifying and displaying these faults on the tablet and validating them or not, j) transmitting these defects, validated or not validated, to the specific database (3), the method further comprising determining the fixed reference point(s), determining a shift of the part (1a) relative to a previous reference image by estimating a movement of the fixed reference points (1b) relative to the fixed reference points on the previous reference image and repositioning an optimal trace of the joint (1c) to be covered on the part (1a) to be checked.

2. Method according to claim 1, wherein instructions are initiated with a view to one or more corrective actions concerning the depositing of the bead of material and / or the relative movement of the part (1a) and the vision machine.

3. Method according to claim 1 or 2, wherein the part (1a) including the bead of material is disposed on a movable support of the cradle type and a movement of this cradle is automatically controlled so as to run said bead in front of the vision head (2) of the vision machine.

4. Method according to claim 1 or 2, wherein the part (1a) including the bead of material is held in a fixed position, the vision machine is arranged on a robotic arm and a movement of this arm is automatically controlled so as to run the bead of material in front of the vision head (2) of the vision machine.

5. Method according to one of claims 1 to 4, wherein the computer is used to define, for each acquired image of the bead of material, an image relating to an ideal bead and to generate corrective parameters.

6. Method according to claim 5, wherein, in step b), continuous learning is performed, making it possible to compensate for dimensional drifts in the parts and drifts in the movement between the parts and the vision machine.

7. Method according to claim 5 or 6, wherein three fixed reference points (1b) are used.

8. Method according to claim 7, wherein the offset of the part (1a) is estimated by calculation, using a triangulation or optimal calculation registration algorithm.

9. Method according to one of claims 1 to 8, wherein segments of the bead of material are defined, each delimited according to its longitudinal extension by two end points located with respect to at least one fixed reference point of the part, and the segments of the bead of material are checked one after the other with the vision machine or simultaneously with several vision machines.

10. Checking method according to claim 9, wherein, in step a), one or more specific physical parameters are defined for each segment of the bead of material.

11. Method according to one of the preceding claims, wherein images of the bead of material deposited on the part (1a) are visualised on the tablet as well as a representation of the ideal position of this bead, are viewed on each image.

12. Method according to one of the preceding claims, implemented for parts intended for the automotive industry.

13. Method according to one of the preceding claims, wherein a program is used to exchange information between the vision head (2) of the vision machine and a robotic arm (8) and / or between this vision head (2) and the computer (5).

14. Checking system for implementing the method according to any one of the preceding claims, the system comprising: at least one vision machine comprising a vision head (2) and a specific database (3), a handling system for generating a relative movement of the vision head and an industrial part, a control unit for controlling the handling system and generating data relating to the relative movement, a computer (5) for configuring the vision head (2) of the vision machine based on the movement-related data transmitted by the control unit, at least one display tool of the tablet type, connected to the specific database, to view a sequence of checking operations, and one or more programs arranged to implement the method.

15. System according to claim 14, further comprising a complementary database, of the remote server type.

16. System according to claim 14 or 15, wherein the vision head (2) of the vision machine comprises a digital camera, annular illumination located around this camera and two projectors (11, 12) arranged at the periphery of the annular illumination at an angular distance of 90°.

17. System according to any one of claims 14 to 16, wherein the handling system comprises a robotic arm (8) carrying the vision head (2) of the vision machine.

18. System according to any one of claims 14 to 17, wherein the handling system comprises a movable nacelle on which the part (1a) carrying the bead of material can be secured.

19. Computer program product comprising program code instructions recorded on a computer-readable medium for implementing the steps of the checking method according to any one of claims 1 to 14, when said program is executed by a computer.