Method for acquiring the position and orientation of at least one user reference marker in a universal installation reference system

Abstract

The invention relates to a method for acquiring the position and orientation of at least one user reference marker in a universal installation reference system, the universal installation reference system being connected to a device for moving a support for receiving a working tool, a reference tool marker being associated with the receiving support, the movement device making it possible to move the receiving support relative to a workstation, the method comprising: - mounting a camera on the receiving support, a camera reference marker being associated with this camera, - affixing a materialisation element of a user reference marker to the workstation, - pre-positioning the camera with respect to the workstation such that the materialisation element is located in the field of view of the camera, - moving the camera into multiple distinct positions relative to the materialisation element so as to allow the camera to capture multiple images of the materialisation element from multiple different positions, these different images allowing the camera to determine the position and orientation of the user reference marker in the camera reference system, and - determining the position and orientation of the user reference marker in the universal installation reference system on the basis of the information transmitted by the camera.

Description

Method for acquiring the position and orientation of at least one user reference frame in a universal installation reference frame.

[0001] The present invention relates to learning and controlling the position of a work tool moved relative to a workstation.

[0002] In many industrial facilities, a work tool must be moved precisely in relation to one or more workstations.

[0003] For example, in tire manufacturing, a gripping tool mounted at the end of a robotic arm is used to transport a finished or semi-finished product from one workstation to another. These different workstations may be part of the same manufacturing facility.

[0004] To avoid production hazards, it is necessary that the movements of the gripping tool be precise and that they remain precise from one production cycle to another.

[0005] In order to control the movements of the work tool in relation to one or more workstations, it is known to associate local reference frames with the different devices of the manufacturing installation and to acquire, through physical measurements and different calculations, the matrices of change of reference frames between these different local reference frames and the universal installation reference frame linked to this manufacturing installation.

[0006] In the case of a gripping tool mounted at the end of a robotic arm, the universal installation marker is associated with the robotic arm, and more specifically with its fixed base, while local markers are associated with the gripping tool and each workstation. For example, a tool marker is associated with the gripping tool, and a user marker is associated with each workstation.

[0007] The present invention relates more specifically to the control of the position and orientation of the tool reference frame in the universal installation reference frame of the robotic arm, and therefore the acquisition of the reference frame change matrix between the universal installation reference frame and the tool reference frame.

[0008] Indeed, even if this coordinate system change matrix between the universal installation coordinate system and the tool coordinate system can be precisely determined during an initial commissioning step of the manufacturing installation, the robotic arm may be subjected to shocks or impacts that alter the position of the gripping tool relative to the robotic arm. This results in a non-conformity of the initially determined coordinate system change matrix with the current state of the installation, and more specifically, of the robotic arm. In such a case, it is therefore necessary to perform a new step to acquire the position and orientation of the tool coordinate system within the universal installation coordinate system of the robotic arm in order to correct the coordinate system change matrix.

[0009] A known method for acquiring the datum change matrix between the universal installation datum and the tool datum at a given workstation involves using a calibration jig positioned precisely on that workstation and representing a user datum on that workstation. This calibration jig typically includes three reference points marked by pins. The method plans to equip the gripping tool with a probing tool such as a point and to probe the different reference points of the calibration template with this probing tool.

[0010] In this well-known method, the probing tool's movements are performed manually by an operator, for example via a human-machine interface such as Teach Pendant®. Therefore, the accuracy achieved depends on the operator's attention and care during the probing operation.

[0011] Furthermore, measurement discrepancies were observed when two different operators performed this probing operation of the three reference points of the template, or when the same operator performed this probing operation twice in a row.

[0012] Therefore, this known method offers neither sufficient precision, for example down to the millimeter, nor the repeatability desired for an industrial application.

[0013] Finally, the calibration jig is often a bulky object that must be handled with care despite its significant weight. Therefore, this jig is impractical to use and requires time during the commissioning of the manufacturing installation, or later to verify or correct the datum change matrix between the universal installation datum and the tool datum.

[0014] The WO2022150800 document proposes a method for creating a 3-dimensional tool coordinate system including the identification of a reference point positioned on, or near, a reference component, the creation of a user coordinate system originating from the reference point, and the creation of a 3-dimensional tool coordinate system at a known position relative to the reference component.

[0015] The method described in this document WO2022150800 also provides that the 3-dimensional tool frame has coordinates substantially identical to the coordinates of the user frame in a universal installation frame, and it provides for positioning a robotic vision system so that the reference component is located in the field of vision of the robotic vision system, this reference component being a calibration grid, and for identifying the coordinates of the reference point in a universal installation frame with the robotic vision system.

[0016] The method described in this document WO2022150800 is more automated than the method using a calibration template. However, for certain industrial applications, there is a need for a method to acquire the position and orientation of at least one user datum in a universal installation datum that offers greater accuracy.

[0017] The present invention aims to overcome the drawbacks of prior art methods.

[0018] To this end, the invention relates to a method for acquiring the position and orientation of at least one user reference frame in a universal installation reference frame, the universal installation reference frame being linked to a device for moving a support for receiving a work tool, a tool reference frame being linked to the support for receiving a work tool, and the moving device allowing the support for receiving a work tool to be moved relative to a work station.

[0019] According to the invention, the acquisition method provides for: - to mount a camera on the receiving bracket of a work tool, with a camera marker linked to this camera, - to affix a physical element representing a user reference point to the workstation, - to pre-position the camera relative to the workstation so that the element representing a user reference point is located within the camera's field of vision, - to move the camera into several distinct positions relative to the materialization element of a user coordinate system so as to allow the camera to capture several images of the materialization element of a user coordinate system from several different positions, these different images allowing the camera to determine the position and orientation of the user coordinate system in the camera coordinate system, - to determine the position and orientation of the user reference frame in the universal installation reference frame from the information relating to the position and orientation of the user reference frame in the camera reference frame transmitted by said camera, the position and orientation of the camera reference frame in the universal installation reference frame having been determined prior to the implementation of the acquisition process, and the position and orientation of the tool reference frame in the universal installation reference frame being known by the displacement device.

[0020] Advantageously, but not necessarily, the invention may also provide that: - the camera is moved into at least three distinct positions relative to the materialization element of a user frame so as to allow the camera to capture at least three images of the materialization element of a user frame from at least three different positions, these different images allowing the camera to determine the position and orientation of the user frame in the camera frame, - The camera is moved by rotation between distinct positions in which the camera captures different images of the user-defined marker's materialization element from different positions. - the camera axis is always inclined relative to a vertical direction when this camera captures the different images of a material element used to determine the location and orientation of the user coordinate system in the camera coordinate system, - The element used to materialize a user reference takes the form of a patch comprising a plurality of patterns arranged in a matrix, - The patterns of the materialization element are circular and arranged on a background of a different color, the color of the patterns being lighter than the color of the background on which the patterns are arranged, - the patterns are white and arranged on a black background.

[0021] When the relocation device allows the receiving support of a work tool to be moved from one workstation to another, the acquisition process includes: - to apply a user marker to each workstation, each user marker affixed to each workstation being different from the user markers affixed to the other workstations, - to successively preposition the camera in relation to each workstation so that each element representing a user reference point is successively located within the camera's field of vision, - to move the camera into several distinct positions relative to each element of a user reference point so as to allow the camera to capture several images of each element of a user reference point from several different positions in order to determine the position and orientation of each user identifier within the camera identifier - to determine by calculations the position and orientation of each user reference frame in the universal installation reference frame from the information relating to the position and orientation of each user reference frame in the camera reference frame transmitted by said camera.

[0022] Advantageously, but not necessarily, the invention may also provide that: - The position and orientation of the camera reference frame within the universal installation reference frame are determined during a camera calibration step performed before the implementation of the acquisition process. - The camera calibration step is performed with a calibration target placed near the moving device and comprising a plurality of patterns arranged in a matrix, - The camera captures different images of said calibration target from different positions relative to this target to determine the position and orientation of the camera reference frame in the universal installation reference frame, - the acquisition process is implemented during the commissioning of the movement device in a manufacturing installation comprising at least one workstation on which a material element of a user reference point is affixed, - the acquisition process is implemented again during the use of the displacement device in the manufacturing installation in order to verify the position and orientation of the tool reference in the universal installation reference, for example following an impact suffered by the displacement device or after a certain period of use of the displacement device in the manufacturing installation, - the acquisition process is again implemented during the use of the displacement device in the manufacturing installation in order to check the position and orientation of the user reference of a workstation in the universal installation reference, for example following a shock suffered by the workstation.

[0023] Other features and advantages of the invention will become apparent in the following description. This description, given by way of example and not limitation, refers to the attached drawings in which: - Figure 1 represents a manufacturing installation in which the acquisition process according to the invention can be implemented, - Figure 2 represents a materialization element of a user reference frame used in the acquisition process according to the invention, and - Figure 3 represents the capture of different images of a materialization element of a user reference carried out in the acquisition process according to the invention.

[0024] The invention relates to a method for acquiring the position and orientation of at least one user reference frame in a universal installation reference frame of a manufacturing installation such as that schematically illustrated in Figure 1.

[0025] This manufacturing installation 10 includes a movement device 12 for a receiving support 14 of a work tool (not shown) relative to at least one workstation. For example, the movement device 12 is a robotic arm mounted on a base 16 fixed to the floor of the workshop in which the manufacturing installation is located. This robotic arm is, for example, of the 6-axis type, that is to say, comprising 6 joints and therefore 6 different axes of rotational mobility between its base 16 and the receiving support 14. The receiving support 14 takes, for example, the form of a flange on which various equipment and / or work tools can be mounted.

[0026] The manufacturing installation 10 comprises at least one workstation P1, and for example, several workstations P1, P2, P3. In the case where the installation comprises several workstations P1, P2, P3, the moving device 12 allows the receiving support of a work tool to be moved from one workstation to another. For example, the work tool mounted on the receiving support 14 is a gripping tool used to transport a finished or semi-finished product (not shown) from one workstation to another. For example, the manufacturing installation 10 is located in a tire manufacturing workshop, and the finished or semi-finished product transported by the moving device 12 is a tire blank or a rubber component intended for the assembly of a tire blank.

[0027] For its implementation, the acquisition method according to the invention provides that a camera 18 is mounted on the receiving support 14 of a work tool. The mounting of this camera 18 on the receiving support 14 may be temporary or permanent. The term "camera" refers to any type of device capable of capturing an image of an object within its field of vision. Preferably, the camera 18 is capable of capturing multiple images. Also preferably, the camera 18 includes means for processing and analyzing the images it has captured. For example, the camera 18 is a camera marketed by the company SENSOPART®.

[0028] For the implementation of the process according to the invention, different reference points are associated with the different components of the manufacturing installation 10. Thus, a universal installation reference point R iu is linked to the displacement device 12, a tool reference R ois linked to the receiving support 14 of a work tool, and a camera reference R c is linked to camera 18. By frame of reference, it is preferably designated as a three-dimensional Cartesian and orthonormal frame of reference. Such a frame of reference comprises an origin point and a basis of three unit vectors that are orthogonal in pairs. For example, the universal installation frame R iu , like each of the other reference frames used in the acquisition method according to the invention, comprises a specific origin point O and three orthogonal unit vectors ë^,

[0029] In order to associate a user reference point with a workstation, the acquisition method according to the invention involves affixing a materialization element 20 of a user reference point R uat a workstation. If the manufacturing installation comprises several workstations P1, P2, P3, the acquisition process involves applying a materialization element 20 of a user reference frame to each workstation. This allows a control unit UC, such as a PLC, to differentiate the user reference frame R from the movement device 12. U I,R U2,RU3 of each workstation P1, P2, P3, each user reference element 20 affixed to each workstation is different from the user reference elements 20 affixed to the other workstations. A user reference element 20 is permanently positioned on a workstation, for example, glued to a flat surface of the workstation. A user reference element 20 is present on a workstation when that workstation is in use. The user reference element 20 is positioned freely on a workstation, that is, without taking any reference or measurement.

[0030] According to the invention, and as illustrated in Figure 2, a materialization element 20 of a user reference takes the form of a patch comprising a plurality of motifs M, for example, one hundred or more, arranged in a matrix. Preferably, to facilitate the To precisely locate the user's reference point, the M patterns of the materialization element are circular and arranged on a background of a different color, the color of the M patterns being lighter than the color of the background on which the patterns are arranged. For example, the M patterns are white and arranged on a black background. For example, a materialization element 20 is a dark-colored square several centimeters on each side, and the M patterns are lighter-colored circles several millimeters on each side. Different materialization elements 20 affixed to different workstations are distinguished from one another by a different number of M patterns and / or by a different arrangement of these M patterns in the rows and / or columns of the pattern matrix. For example, the materialization elements 20 are target marks marketed by the company SENSOPART®.

[0031] Once a materialization element 20 has been placed on a workstation, the acquisition process involves: - to pre-position the camera 18 relative to the workstation so that the materialization element 20 of a user reference point R u is located within the field of vision of camera 18, - to move the camera 18 into several distinct positions relative to the materialization element 20 of a user reference frame R u so as to allow camera 18 to capture several images of the materialization element 20 of a user reference R u from several different positions.

[0032] When the manufacturing installation 10 comprises different workstations P1, P2, P3, and a materialization element 20 of a user reference R U I, R U 2. RU3 has been affixed to each of these workstations; the work procedure includes: - to successively preposition camera 18 in relation to each workstation P1, P2, P3 so that each materialization element 20 of a user reference R U I, RU2, RU3 are successively located in the field of vision of camera 18, - to move the camera 18 into several distinct positions relative to each materialization element 20 of a user reference frame R U I, R U 2, RU3 so as to allow camera 18 to capture several images of each materialization element 20 of a user reference point R U I, R U 2,RU3 from several different positions in order to determine the position and orientation of each user reference frame R U I, R U 2, RU3 in camera frame R c .

[0033] Advantageously, since camera 18 has its own image processing and analysis capabilities and its own camera reference Rc The different images of the materialization element 20 captured by the camera allow it to determine the position and orientation of the user reference frame R u in the camera frame R c The plurality of patterns M arranged in a matrix on the materialization element 20 allows for a precise localization of the user reference frame R u in the camera frame R c via image processing performed by the camera. For example, camera 18 analyzes the deformations of the different patterns M to determine the position and orientation of the user coordinate system R u in the camera frame R c Advantageously, the different positions taken by the camera relative to the materialization element 20 and the different images of the materialization element 20 captured by the camera in these different positions improve the accuracy of the localization of the user reference frame R uin the camera frame R c obtained through image processing and to make this location more reliable and more representative of reality.

[0034] For example, pre-positioning camera 18 relative to the workstation allows the materialization element 20 of a user reference point R to be placed u The field of view of camera 18 is achieved through human intervention. For example, an operator directs the movements of the displacement device 12 via a human-machine interface until the materialization element 20 of a user reference point R u is located within the camera's field of vision.

[0035] Following this pre-positioning of the camera 18, the movements of the camera 18 in several distinct positions relative to the materialization element 20, allowing for the capture of several images of the materialization element 20, are carried out automatically by the movement device 12. For example, the control unit UC, like an automaton, of the movement device 12 operates these movements of the camera 18 in these different positions.

[0036] For example, the camera 18 is moved to two distinct positions relative to the materialization element 20 of a user frame so as to allow the camera 18 to capture two different images of the materialization element 20 of a user frame R u from two different positions. Thus, two different images of the materialization element 20 are used by the camera 18 to determine the position and orientation of the user frame R uin the camera frame R c As shown in Figure 3, the camera 18 is, for example, moved by rotation R1, R2 between two distinct positions in which the camera 18 captures different images of the materialization element 20 of a user frame R ufrom different positions. For example, two distinct camera positions 18 relative to the materialization element 20 are obtained from a central position of the camera 18 and two lateral positions obtained by rotating the camera. For example, one of these lateral camera positions is obtained by a clockwise rotation R2 from the central position, while the other lateral position is obtained by a counterclockwise rotation R1 from the central position. For example, these camera rotations R1, R2 have the same amplitude. For example, the amplitudes of these camera rotations R1, R2 are between 10 and 30 degrees. For example, these camera rotations R1, R2 are performed around different axes.

[0037] Preferably, to obtain optimal localization accuracy and reliability, the camera 18 is moved to at least three distinct positions relative to the user frame material 20 so as to allow the camera 18 to capture at least three images of the user frame material 20 from at least three different positions. Thus, at least three different images are used by the camera 18 to determine the position and orientation of the user frame R u in the camera frame R cFor example, three distinct camera positions 18 relative to the materialization element 20 are obtained from a central camera position 18 and three lateral positions obtained by rotating the camera. For example, one of these lateral camera positions is obtained by a clockwise rotation from the central position, while the other two lateral positions are obtained by two counterclockwise rotations of different amplitudes from the central position. For example, the amplitude of these three camera rotations is between 10 and 30 degrees.

[0038] For example, after its pre-positioning relative to the materialization element 20 and before being moved into the different image capture positions of the materialization element 20, the movement device 12 operates a The camera 18 is realigned with respect to the materialization element 20. This realignment preferably aims to position the camera 18 vertically above the materialization element 20. During this realignment, the movement device 12 also readjusts the distance between the camera 18 and the materialization element 20. For example, the camera 18 is positioned at a distance of between 45 and 80 cm from the materialization element 20. Advantageously, since the camera 18 is connected to the control unit UC of the movement device 12, this realignment and readjustment of the camera's distance from the materialization element 20 are achieved thanks to an initial image of the materialization element 20 captured and analyzed by the camera 18 from its pre-positioning position relative to the materialization element 20.For example, when two or three distinct camera positions 18 relative to the materialization element 20 are obtained from a central position of the camera 18 and two or three lateral positions obtained by rotating the camera, the central position of the camera 18 corresponds to the position obtained after this realignment and readjustment of the distance of the camera relative to the materialization element 20.

[0039] Preferably, in the acquisition method according to the invention, the axis of the camera 18 is always inclined with respect to a vertical direction when this camera captures the different images of a materialization element 20 used to determine the location and orientation of the user reference frame R u in the camera frame R c .

[0040] When the camera 18 uses different images of a materialization element 20 to determine the position and orientation of a user frame R u in the camera frame R c , each coordinate of the user coordinate system R u in the camera frame R c The value captured by the camera and transmitted to the control unit (CU) of the movement device is, for example, an average of the different values ​​of this same coordinate in the user frame R u in the camera frame R c determined by the camera for each of these different images.

[0041] Once the position and orientation of a user coordinate system R are known u in the camera frame R c determined by camera 18, the acquisition process involves determining, notably through various calculations and coordinate system transformation matrices, the position and orientation of this user coordinate system R u in the universal installation reference Riu of the displacement device 12 based on information relating to the position and orientation of the user reference frame R u in the camera frame R c transmitted by said camera.

[0042] When the manufacturing installation 10 comprises different workstations P1, P2, P3 and the position and orientation of each user reference R U I,R U 2, RU3 in camera frame R c were determined by camera 18; the acquisition process involves determining, notably through various calculations and coordinate system transformation matrices, the position and orientation of each user coordinate system R U I, R U 2, RU3 in the universal installation reference R iu based on information relating to the position and orientation of each user reference point R U I, R U 2,RU3 in camera frame R c transmitted by said camera.

[0043] For example, with camera 18 connected to the control unit UC of the displacement device 12, the position and orientation of one or more user reference frames in the universal installation reference frame R can be determined, notably using various calculations and coordinate system transformation matrices. iu the movement device 12 is carried out by this control unit UC, based on information transmitted by this camera 18.

[0044] In order to determine the position and orientation of one or more user reference points in the universal installation reference frame R iu From the information transmitted by the camera 18, it is necessary, for example for the control unit UC, to know the position and orientation of the camera reference frame R. c in the universal installation reference R iu and the position and orientation of the tool reference frame R oin the universal installation reference R iu Indeed, the different coordinate system change matrices of a manufacturing installation 10 according to the invention are related by the following relationship: Mr. Riu-Ro = M Riu-Ru x (M Ru-Rc x M Rc-Ro) with: M = Matrix of change of reference frame between the universal installation reference frame R iu of the displacement device 12 and the tool reference R o of the receiving support 14, M Riu-Ru = Matrix of coordinate system change between the universal installation coordinate system R iu of the displacement device 12 and the user reference R u of a material element 20 affixed to a workstation, MR U -Rc = Matrix of change of coordinate system between the user coordinate system R u of a materialization element 20 affixed to a workstation and camera marker R c of camera 18, and M = Change of coordinate matrix between the camera coordinate system R cof camera 18 and tool marker R o of the receiving support 14.

[0045] As an alternative or complement to coordinate transformation calculations performed using matrices, the acquisition process may also require the control unit (CU) to perform some of these coordinate transformation calculations using vectors. For example, these calculations can be performed with Cartesian and / or spherical coordinates.

[0046] For example, the position and orientation of the camera reference frame R c in the universal installation reference R iu are determined prior to the implementation of the acquisition method according to the invention, and the position and orientation of the tool reference frame R o in the universal installation reference R iu are known by the displacement device 12, and more specifically by its control unit UC. For example, the position and orientation of the tool reference frame R oin the universal installation reference R iu are determined at the factory by the manufacturer of the displacement device 12 and stored in the control unit UC of this displacement device 12.

[0047] Since the displacement device 12 is not equipped with the camera 18 by its manufacturer, this camera 18 is subsequently mounted on the receiving support 14, for example, for the implementation of the acquisition method. Also, the acquisition method according to the invention provides that the position and orientation of the camera reference frame R c in the universal installation reference R iu are determined during a camera calibration step carried out before the implementation of the acquisition process.

[0048] For example, the calibration step of camera 18 is performed with a calibration target (not shown) positioned near the movement device 12 and comprising a plurality of patterns, for example, more than one hundred, arranged in a matrix. For example, a calibration target might consist of light-colored circular patterns arranged in a matrix on a dark background. For example, the patterns on the calibration target might be white circles arranged in a matrix on a black background. This calibration target is, for example, positioned near the movement device 12 and the workstation(s) P1, P2, P3 by an operator.

[0049] In order to determine the position and orientation of the camera reference frame R c in the universal installation reference R iuThe camera captures different images of the calibration target from various positions relative to it. For example, the camera captures ten images of the calibration target from ten different positions. The displacement device 12 moves the camera 18 between these different calibration positions. Even if the calibration target is positioned arbitrarily relative to the displacement device 12, since the position of this calibration target remains constant throughout the calibration process, it constitutes a fixed reference point that allows the control unit CU to deduce the position and location of the camera 18 relative to the displacement device 12, and therefore the position and location of the camera reference frame R. c in the universal installation reference R iu .

[0050] As previously mentioned, the position and orientation of the tool reference frame Ro of the receiving support 14 in the universal installation reference R iu The values ​​of the displacement device 12 are determined by the manufacturer of the displacement device 12 and stored in the control unit UC of this displacement device 12. Therefore, the acquisition method according to the invention provides for an initial implementation during the commissioning of the displacement device 12 in a manufacturing installation 10 comprising at least one workstation on which a user reference marker 20 is affixed. Advantageously, during this initial implementation of the acquisition method, the displacement device 12 and the receiving support 14 of a work tool have not yet been used in manufacturing and have therefore not yet been subjected to shocks likely to alter the position and orientation of the tool reference marker R o in the universal installation reference R iudetermined by the manufacturer of the displacement device 12 and entered in its control unit UC.

[0051] Once the displacement device 12 has been commissioned and the initial implementation of the acquisition method according to the invention has been completed, the displacement device is used to perform various tasks within the manufacturing installation. During the execution of these tasks, the displacement device, and more specifically one of its articulated arms, may be subjected to one or more impacts. These impacts are likely to alter the position and orientation of the receiving support, and therefore of the tool reference R. o , the universal installation reference R iu and to make the movements of the moving device 12 imprecise and therefore those of the work tool mounted on the receiving support 14, which can lead to failures in carrying out certain tasks or to dangerous situations.

[0052] Furthermore, over time, and simply due to wear and tear on certain mechanical parts of the displacement device 12 and the large number of repeated movements by the displacement device, the position and orientation of the receiving support, and therefore of the tool reference R, may become misaligned. o , in the universal installation reference R iu be modified little by little.

[0053] Also, the acquisition method according to the invention provides for other implementations during the use of the displacement device 12 in the manufacturing installation 10 in order to verify the position and orientation of the tool reference R o , in the universal installation reference R iu , for example as a result of an impact suffered by the displacement device 12 or after a certain period of use of the displacement device 12 in the manufacturing installation 10.

[0054] Like the displacement device 12, a workstation P1, P2, P3 can be subjected to shocks during its use in the manufacturing installation. Therefore, the acquisition method according to the invention can be implemented during the use of the displacement device 12 in the manufacturing installation 10 in order to verify the position and orientation of the user reference frame R u of a workstation in the universal installation reference R iu , for example, following an impact to the workstation.

Claims

Demands 1. Method for acquiring the position and orientation of at least one user reference frame in a universal installation reference frame, the universal installation reference frame being linked to a device for moving a support for receiving a work tool, a tool reference frame being linked to the support for receiving a work tool, the moving device allowing the support for receiving a work tool to be moved relative to a workstation, the acquisition method being characterized in that it provides for: - to mount a camera on the receiving bracket of a work tool, with a camera marker linked to this camera, - to affix a physical element representing a user reference point to the workstation, - to pre-position the camera relative to the workstation so that the element representing a user reference point is located within the camera's field of vision, - to move the camera into several distinct positions relative to the materialization element of a user coordinate system so as to allow the camera to capture several images of the materialization element of a user coordinate system from several different positions, these different images allowing the camera to determine the position and orientation of the user coordinate system in the camera coordinate system, and - to determine the position and orientation of the user reference frame in the universal installation reference frame from the information relating to the position and orientation of the user reference frame in the camera reference frame transmitted by said camera, the position and orientation of the camera reference frame in the universal installation reference frame having been determined prior to the implementation of the acquisition process, and the position and orientation of the tool reference frame in the universal installation reference frame being known by the displacement device.

2. Acquisition method according to claim 1, wherein the camera is moved into at least three distinct positions relative to the materialization element of a user frame so as to enable the camera to capture at least three images of the materialization element of a user frame from at least three different positions, these different images enabling the camera to determine the position and orientation of the user frame in the camera frame.

3. Acquisition method according to claim 1 or 2, wherein the camera is moved by rotation between distinct positions in which the camera captures different images of the materialization element of a user reference point from different positions.

4. An acquisition method according to any one of the preceding claims, wherein the camera axis is always inclined with respect to a vertical direction when this The camera captures the different images of a materialization element used to determine the location and orientation of the user coordinate system in the camera coordinate system.

5. Acquisition method according to any one of the preceding claims, wherein the materialization element of a user marker takes the form of a patch comprising a plurality of patterns arranged in a matrix.

6. Acquisition method according to claim 5, wherein the patterns of the materialization element are circular and arranged on a background of different color, the color of the patterns being lighter than the color of the background on which the patterns are arranged.

7. Acquisition method according to claim 6, wherein the patterns are white and arranged on a black background.

8. A method of acquisition according to any one of the preceding claims, wherein, - the relocation device enabling the receptacle of a work tool to be moved from one workstation to another; the acquisition process includes: - to apply a user marker to each workstation, each user marker affixed to each workstation being different from the user markers affixed to the other workstations, - to successively preposition the camera in relation to each workstation so that each element representing a user reference point is successively located within the camera's field of vision, - to move the camera into several distinct positions relative to each element of a user reference frame so as to allow the camera to capture several images of each element of a user reference frame from several different positions in order to determine the position and orientation of each user reference frame in the camera frame, - to determine by calculations the position and orientation of each user reference frame in the universal installation reference frame from the information relating to the position and orientation of each user reference frame in the camera reference frame transmitted by said camera.

9. Acquisition method according to any one of the preceding claims, wherein the position and orientation of the camera reference frame in the universal installation reference frame are determined during a camera calibration step carried out before the implementation of the acquisition method.

10. Acquisition method according to claim 9, wherein the camera calibration step is carried out with a calibration target disposed near the displacement device and comprising a plurality of patterns arranged in a matrix.

11. An acquisition method according to claim 9 or 10, wherein the camera captures different images of said calibration target from different positions relative to that target to determine the position and orientation of the reference mark camera in the universal installation location.

12. Acquisition method according to any one of the preceding claims, the acquisition method being implemented during the commissioning of the displacement device in a manufacturing installation comprising at least one workstation on which is affixed a materialization element of a user reference.

13. Acquisition method according to claim 12, the acquisition method being implemented again during the use of the displacement device in the manufacturing installation in order to verify the position and orientation of the tool reference in the universal installation reference frame, for example following an impact to the displacement device or after a certain period of use of the displacement device in the manufacturing installation.

14. Acquisition method according to claim 12 or 13, the acquisition method being implemented again during the use of the displacement device in the manufacturing installation in order to verify the position and orientation of the user reference frame of a workstation in the universal installation reference frame, for example following an impact to the workstation.

Images