Method and system for automatically generating welding plans for (quasi-) one-off workpieces

Abstract

A method for automatically generating a welding plan for a workpiece, in particular a (quasi-) one-off workpiece, comprising the steps of: moving a sensor equipped with a camera and a laser light source over the workpiece while the laser light source emits a laser beam that is projected onto the workpiece; using the camera to acquire laser line height data representing the local height of the laser line projected on the workpiece; generating a 3D representation of the workpiece based on the local height data acquired by the sensor in step b); defining a weld seam at the contact line between a structural member and a base plate based on the 3D representation of the workpiece; and generating a welding plan based on the set of weld seams.

Description

[Technical Field]

[0001] The present invention relates to a method and system for automatically generating a welding plan for a workpiece, in particular a (quasi-) one-off workpiece, and a method for automatically welding the workpiece. [Background technology]

[0002] Automated welding of mass-produced parts has developed rapidly over the past decade. Fully automated factories are now in operation, welding parts an unlimited number of times at very high speed and precision. The requirements for such an automated process are that the parts used are precisely positioned, tolerances are small, and the welding movements are predefined and always the same. Such automated welding robots can be used to assemble cars, for example, in stages.

[0003] In contrast, the present invention relates to welding workpieces that are typically (quasi) one-off, include parts with larger tolerances, and where the welding plan is not also defined. For example, the methods disclosed herein can be used to construct large, one-off metal structures (or portions thereof) such as cruise ships, other watercraft, offshore structures, and other industrial equipment by welding.

[0004] WO2018 / 215592A1 discloses a method for automatic seam welding of workpieces comprising a base plate having a pattern of upstanding structural members, said workpieces being placed on a support base, said apparatus comprising: - an overhead support equipped with at least one robotic device, at least one overhead scanner (e.g. a laser scanner, preferably a LIDAR scanner), the robotic device includes an articulated arm and is configured such that a head of the articulated arm assumes an active position adjacent to the support base; ---The head includes a distance sensor, the robotic device carries a welding tool having a welding gun with a welding torch; the sensor is positionable at different positions within a localized area of ​​the workpiece in the active position, the distance sensor is configured to generate local information about the position of seam lines within a local area, such as information about the positions of the edges of profiles or intersections of profiles that are present within or bound the local area, - a computer device storing: data representing an established overall 3D topographical image of said workpiece; data representative of the generated local information; --information representing the geometric data of each profile, and - weld seam information regarding the weld seam applied to weld each profile to the base plate; The method comprises the steps of: - commencing relative movement of at least one overhead scanner over the workpiece with respect to the support stage; - establishing the overall 3D topographical image of the workpiece by moving the at least one overhead scanner relative to the workpiece; - positioning the sensors at different positions within each local region of the workpiece to generate the local information regarding seam line position; - storing data representative of the established overall 3D topographical image of the workpiece; - storing data representative of said generated local information; - providing information representative of geometric data for each profile, - providing weld seam information regarding the weld seam applied to weld each profile to the base plate, the weld seam information comprising or consisting of information regarding the weld leg dimensions, - identifying each profile by comparing the stored data representative of the overall 3D terrain image with the stored information representative of the geometric data of each profile, - initiating welding within the localized region and using the stored weld seam information to move the welding gun along the seam line to perform a seam weld.

[0005] The LIDAR scanner used in WO2018 / 215592 A1 transmits and receives a laser beam. The time difference between transmitting and receiving the laser beam can be used to determine the distance between the laser source and the target object using the speed of light. A disadvantage of this method is that the images obtained by the LIDAR scanner are coarse and inaccurate for the dimensions of typical workpieces of interest, and overhead scanners can only obtain the general position of a part or element. In particular, it is difficult to achieve a positional accuracy of less than 2 mm with a LIDAR scanner. While this is sufficient for measuring the distance between car runs, it is not sufficient for generating welding plans for workpieces. As a result, according to WO2018 / 215592 A1, a detailed scan is required in addition to the overhead scan to obtain an accurate "image" of the workpiece. This results in a time-consuming and relatively slow method.

[0006] A further disadvantage of this method is that it requires a database that stores geometric data and weld seam information for each structural element used, which on the one hand makes it impossible to implement the method without purchasing a dedicated software package, and on the other hand makes it impossible to successfully complete the method if a unique structural element that is not stored in the database is used for a particular workpiece.

[0007] Some of these disadvantages are partially overcome by the method proposed in WO2021 / 116299 A1, which discloses a method for controlling a welding motion provided by a welding machine controlled by an automatic motion generating mechanism, the method comprising the steps of: - acquiring a set of welding data during a welding operation; - calculating at least a first portion and at least a second portion of the welding data to provide calculated data, the calculated data being indicative of an anomaly; - transferring an abnormal output to a robot controller controlling the welding machine and the automatic motion generating mechanism.

[0008] In particular, compared to WO2018 / 215592 A1, in WO2021 / 116299 A1 less detailed information about the weld seam needs to be obtained before the welding process begins, since information is generated during the welding process (including information about anomalies during that process). However, a database is still required to generate a suitable welding plan. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to overcome the disadvantages associated with the method disclosed in WO2018 / 215592 A1 and adopts a fundamentally different approach to the method disclosed in WO2021 / 116299 A1.

[0010] In particular, it is an object of the present invention to enable the automatic generation of welding plans without requiring substantial prior knowledge of the workpiece / structural members to be used thereon. [Means for solving the problem]

[0011] Therefore, a first aspect of the present invention relates to a method for automatically generating a welding plan for a workpiece, in particular a (quasi-) one-off workpiece, comprising: the workpiece comprises a base plate and one or more structural members projecting upwardly from the base plate; a sensor is used that includes a laser source and a camera, the laser source and camera being fixedly positioned at an angle of 10° to 60° relative to each other, the laser source being configured to generate a laser beam, the camera being configured to record the laser beam, and the sensor being movable relative to the workpiece; The method comprises: a) moving a sensor over a workpiece while a laser source emits a laser beam that is projected onto the workpiece; b) using a camera to acquire laser line height data representing the local height of the laser line projected onto the workpiece; c) generating a 3D representation of the workpiece based on the local height data acquired by the sensor in step b); d) defining a weld seam at the contact line between the structural member and the base plate based on the 3D representation of the workpiece; e) generating a welding plan based on the set of weld seams; A method comprising:

[0012] To obtain laser line height data, the sensor measures the distance to the laser line projected by the laser source, for example, using a range camera. Positioning the laser source and camera at an angle in a fixed position provides a much more accurate view of the workpiece than using a LIDAR sensor. In some embodiments, submillimeter accuracy is achieved, eliminating the need for time-consuming detailed measurement steps along the entire length of the structural member. The specific sensor placement allows the sensor to measure the return angle of the reflected laser light using the principle of triangulation. By comparing the difference between the direction of the laser beam as it leaves the laser source and the direction of the same beam as it is reflected by the workpiece and enters the camera, combined with knowledge of the relative positions of the camera and the laser source, the distance to the workpiece can be measured with high accuracy. Another advantage of positioning the camera at an angle relative to the laser source is that it can directly detect rat holes, drain holes, and the edges of structural members, even if the structural member includes a horizontal section at its top, allowing these "anomalies" to be directly accounted for in the welding plan.

[0013] Thus, the time required to complete the scanning process may be reduced by up to 50% or more compared to conventional methods. Of course, the majority of the time is still spent actually welding the structural members to the base plate and / or to each other, and this portion of the process is saved little or nothing with the present method compared to conventional welding processes planned using applicant's proprietary RinasWeld program.

[0014] As a further advantage, it is not necessary to have a 2D or 3D computer drawing of the workpiece and still be able to weld it automatically. Nor is it necessary to have a database containing all the different structural members. The elimination of these requirements makes automated welding available to many more workshops around the world compared to traditional automated welding methods that required such databases and computer drawings.

[0015] It also makes it possible to automatically detect and plan for anomalies in structural components and specific to individual items.

[0016] Yet another advantage of the present method is that, as confirmed by testing, the configuration described herein is much better able to handle reflective surfaces, such as polished surfaces of workpieces, compared to methods using LIDAR technology, and the data sets obtained for such surfaces more accurately reflect real-world conditions.

[0017] A further advantage of this method is that the angle of the camera relative to the laser beam emitted by the laser source allows the sensor to "see under" T-shaped or other structural members with tops, so information about the weld seam can be obtained during the first scan regardless of the structural member used, which is not always possible when using LIDAR technology.

[0018] In accordance with the present invention, a welding plan for a workpiece can be automatically generated. The term "automatically" does not imply complete human intervention. For example, human intervention may still be required to temporarily position the workpiece, such as temporarily attaching structural members to a base plate with spot welds. In addition, certain embodiments may require a human to verify certain conditions / assumptions during the process and / or provide certain input values ​​in advance for the process to execute correctly.

[0019] As explained above, the present method is primarily intended for one-off or near-one-off workpieces, e.g., workpieces with relatively high margins of uncertainty regarding component positioning and dimensions. When mass production is required, it is likely more efficient to pre-program the welding operations of a welding robot rather than deriving a welding plan for each workpiece.

[0020] The workpiece for which the method is applied typically includes a base plate and one or more structural members projecting upward from the base plate. For example, the structural members may be temporarily attached to the base plate by spot welding. When performing the method, a weld seam is defined at the contact line between the structural members and the base plate. In embodiments, the structural members may contact each other. In such embodiments, a further weld seam may be defined at the contact line between the two structural members.

[0021] According to the present invention, the sensor includes a camera and a laser that are fixedly positioned relative to each other. Furthermore, the sensor itself may be positioned at an angle relative to a line perpendicular to the workpiece, such that the laser source projects a laser line at a first angle relative to the workpiece, and the camera observes the laser light at a second angle greater than the first angle. Fixing the relative orientation of the sensor and laser source has the advantage that the trigonometric calculations are always the same when calculating the height of the laser line projected on the workpiece relative to either the camera or the laser source, and measurement errors from one orientation to the other do not introduce uncertainty into the calculation. Preferably, some calibration is performed between the laser source and the camera during the initial movement step of the method defined above.

[0022] In principle, any laser source capable of generating a laser beam can be used according to the invention, however it is advantageous if it is capable of generating a laser beam of constant width, for example having an arc shape ranging from 20° to 180°.

[0023] In principle, any camera capable of recording the distance to the laser line projected by the laser source with the aid of a processor can be used according to the present invention. In the applicant's first prototype, a Wenglor MLWL275 sensor was used for this purpose. However, it is likely that other sensors will produce equally satisfactory results.

[0024] According to the invention, the sensor is positioned above the workpiece and faces it. In a practical embodiment, the workpiece rests on the floor or a support structure, while the sensor is located on the gantry beam. However, options other than the gantry beam are also possible.

[0025] According to the present invention, there is provided a laser light source and a laser sensor.

[0026] According to the present invention, in the first method step, the sensor is moved over the workpiece. Importantly, at this point, prior knowledge of the workpiece is not required in principle to carry out the methods described herein. In a practical embodiment, this may be achieved by holding the workpiece stationary and moving the sensor. However, it is not excluded to move the workpiece relative to these components while keeping the sensor stationary. This movement is preferably carried out until the entire surface of the workpiece is inspected using the laser light source and camera. For example, an operator may manually specify the dimensions of the workpiece, and processing software may identify the edge of the workpiece during the movement step.

[0027] According to the present invention, the camera may measure the angle at which the laser beam reflected from the workpiece is received. Since the angle between the laser source and the camera is constant, this angle can be converted into the distance between the camera and the object. Since the height between the substructure and the camera is constant, this distance can be converted into the local height of the workpiece / height of the laser line.

[0028] According to the present invention, the local height of the workpiece may be collected as a point cloud, the resolution of which may depend, for example, on the speed at which the sensor is moved relative to the workpiece and / or the processing power of the hardware components. Using dedicated software tools and programs, these data points, e.g., the point cloud, may be integrated into a 3D representation of the workpiece, in a format that is frequently used, for example, in computer-aided design programs and that may also be usable by other (computer) programs.

[0029] According to the present invention, once the 3D representation of the workpiece has been generated, in a subsequent step the contact lines between the structural member and the base plate are obtained. At these contact lines, a weld seam is defined for welding the structural member to the base plate to obtain the workpiece. The detection of the contact lines can be performed, for example, using the RinasWeld program provided by the applicant, although other software may also be used.

[0030] Thus, the final step is to generate a weld plan for performing the weld, a step that is preferably performed in an automated manner using computer software tools.

[0031] This step is preferably followed by automatically welding the structural member to the base plate according to the weld plan, for example using a robotic welding torch positioned above the workpiece.

[0032] Generally speaking, the direction of movement of the sensor relative to the workpiece does not significantly affect the results obtained, as long as the entire surface of the workpiece is scanned.

[0033] In a practical embodiment of the present invention, the sensor movement may be in the longitudinal direction of the workpiece. This movement may be a continuous linear movement. Alternatively, depending on, for example, the processing power of the software, the movement may be intermittent, in which case the laser source and sensor are intermittently moved forward and backward relative to the workpiece, resulting in a higher resolution in the sense that a particular portion of the workpiece is scanned twice, resulting in a larger number of data points. In particular, at the beginning, end, or intersection of a structural member with another structural member, two (e.g., three) scans may be required to obtain a better data set and greater accuracy.

[0034] In an embodiment of the present invention, the sensor moves laterally across the workpiece. Movement in this direction may be continuous or intermittent, as described above. This movement may be combined with longitudinal movement, thereby scanning the entire workpiece twice in two directions, providing higher resolution. However, in some embodiments, scanning only longitudinally or only laterally may provide sufficient resolution, in which case movement in the other direction may be omitted. In this embodiment, the laser beam emitted from the laser source may have an arc shape, e.g., with a width between 20° and 180°. Preferably, as the laser source moves along the workpiece, the entire workpiece is illuminated with laser light at a specific cross-sectional area. To achieve this, the beam emitted from the laser source must be increased or decreased depending on the precise height between the workpiece and the laser source.

[0035] In an embodiment of the present invention, the color of the laser light emitted from the laser light source is blue, for example, having a wavelength of 450 to 500 nm. Without intending to be bound by any particular theory, the applicant has surprisingly discovered that scan results obtained using blue laser light are more accurate and have less noise than scan results obtained using red laser light.

[0036] In an embodiment of the present invention, the local height of the laser line is obtained in the form of a point cloud.

[0037] In such an embodiment, a plane can be fitted onto the point cloud to convert the local height data obtained as a point cloud into a 3D representation of the workpiece. An advantage of this method is that welding plans can be generated much faster when structural members have imperfections in real life, such as larger or smaller curvatures. In practice, it has been determined that a 3D representation based on plane fitting does not adversely affect the resulting welding results, because even when a 3D representation is available initially (and the scanning method described herein is not used), the 3D representation similarly assumes that the structural members are straight, which may not be the case in reality. In practice, welding robots may self-correct for such imperfections. Another advantage is that by converting point cloud data into a 3D representation using plane fitting, 3D representations can be generated with smaller data sets, significantly increasing the speed of data / file export / exchange.

[0038] In this embodiment, the step of generating a 3D representation of the workpiece includes a step of filtering out extraneous objects other than the structural members on the base plate and / or filtering out reflections and / or noise from the data acquired by the sensor, which can be achieved for example by dedicated pre-processing / post-processing software, with the advantage that welds are not planned in unwanted locations.

[0039] In embodiments of the present invention, the structural members disposed on the base plate include T-shaped structural members, angled structural members, I-shaped structural members, valve structural members, and / or bar structural members, which may include ratholes, tapered edges, and / or notches near or within the contact line. Advantageously, all of these shapes and anomalies are recognizable by the methods described herein.

[0040] In an embodiment of the present invention, a weld seam is further defined at the contact line of each of the two structural members. In addition to welding a structural member to a base plate, it may be desirable to weld two structural members together, for example, along a perpendicular line defined by the contact line between the two structural members. Such contact lines can also be advantageously detected by the present method.

[0041] A second aspect of the present invention relates to a method for automatically welding workpieces, comprising: The steps defined above, and welding the structural member to the base plate using a welding torch according to a welding plan to obtain a workpiece; A method comprising:

[0042] The advantages obtained by the method according to the first aspect are similarly obtained by the method according to the second aspect, and the embodiments described in relation to the first aspect above can be considered to be applicable to the method according to the second aspect as well.

[0043] In particular, in embodiments of the present invention, between the step of generating the welding plan and the step of performing the weld, detailed measurements can be performed to identify the exact start and / or end points of the weld seam, for example using distance sensors integrated into the welding torch and / or contact sensors integrated into the welding torch.

[0044] Alternatively, and additionally, detailed measurements can be taken during the welding step, for example to more precisely determine the desired end point of the weld seam, which can likewise be performed using distance sensors integrated into the welding gun and / or contact sensors integrated into the welding torch.

[0045] Instead of taking detailed measurements along the entire length of all structural members, only the start and / or end points of all or some structural members may be inspected more carefully, especially in locations where a resolution / accuracy of ±1 mm has not previously been achieved.

[0046] A third aspect of the present invention relates to a system for automatically generating a welding plan for a workpiece, particularly a (quasi-) one-off workpiece, including a base plate and one or more structural members protruding upward from the base plate, a laser source configured to generate a laser beam; a camera positioned at a fixed position relative to the laser light source at an angle of 10° to 60° relative to a center line of the laser beam emitted from the laser light source, and configured to record the laser beam; Equipped with the laser light source and the camera form a sensor disposed above the workpiece and configured to be movable relative to the workpiece; a processor; The processor calculating laser line height data representing a local height of the laser line projected onto the workpiece based on the recording provided by the camera; generating a 3D representation (100') of the workpiece (100) based on the local height data; defining a weld seam at a contact line between the structural member and the base plate based on a 3D representation of the workpiece; generating a welding plan based on the set of weld seams; configured to perform method.

[0047] In other words, the third aspect of the present invention relates to a system for carrying out the method according to the first aspect. The advantages obtained by the method according to the first aspect are also obtained by the system according to the third aspect. The embodiments described above with respect to the third aspect can also be considered for the system according to the second aspect.

[0048] Details of the present invention are further described below with reference to the accompanying drawings, in which similar or identical components are designated with the same reference numerals. [Brief explanation of the drawings]

[0049] [Figure 1] FIG. 1 shows a schematic of a workpiece that is one example of many different possible examples for which a welding plan needs to be generated. [Figure 2A] FIG. 2A shows a schematic representation of some of the many different possible details on a structural member of a workpiece. [Figure 2B] FIG. 2B shows a schematic representation of some of the many different possible details on the structural members of the workpiece. [Figure 2C] FIG. 2C shows a schematic representation of some of the many different possible details on the structural members of the workpiece. [Figure 3] FIG. 3 shows a schematic of one possible embodiment of a sensor and laser source positioned above the working area. [Figure 4] FIG. 4 shows a schematic representation of one possible alternative embodiment of a sensor and laser source positioned above the working area. [Figure 5A] FIG. 5A shows a schematic representation of the field of view for two different camera arrangements. [Figure 5B] FIG. 5B shows a schematic representation of the field of view for two different camera arrangements. [Figure 6A] FIG. 6A shows a schematic diagram of a point cloud of the workpiece of FIG. 1 acquired using a sensor and without prior knowledge of the workpiece. [Figure 6B] FIG. 6B shows a schematic representation of the workpiece of FIG. 6A after the point cloud has been converted into a 3D representation. DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 shows a schematic representation of a workpiece 100. The methods described herein are typically applied to a one-off or quasi-one-off workpiece 100, such as a portion of a large metal structure, such as an offshore installation, a cruise ship, a naval vessel, or other similar structure. These structures are typically "one-off" designs designed to customer specifications. While several identical structures may be manufactured, mass production of these structures is uncommon. Therefore, constructing such structures requires the assembly of multiple workpieces 100. The workpiece 100 may have dimensions ranging from several meters to tens of meters in width and several meters to tens of meters, or even hundreds of meters or more in length. The workpiece 100 includes a base plate 110 and structural members 120 and 130. As shown, the base plate 110 may have various cutouts, and the structural members 120 and 130 may be positioned at essentially any location and in any orientation on the base plate 110. The structural members may have heights ranging from 5 cm to 50 cm and protrude upward from the base plate 110. The structural members 120, 130 are welded to the base plate 110 to form the workpiece 100. Traditionally, welding of such one-off structures has been performed manually, but robotic welding of these structures is desirable to reduce costs and / or increase production capacity. Welding occurs at a horizontal contact line 200 between the structural member 120 and the base plate 110 and / or a vertical contact line 300 between the two structural members 120, 130.

[0051] When robotic operations are desired to assemble workpiece 100, structural members 120, 130 are typically first tack-attached, e.g., by hand, typically by spot welding or tack welding, to base plate 110. It should be understood that in this type of structure, the size and placement variations of structural members 120, 130 can be relatively large, and therefore, a welding plan is not derived until structural members 120, 130 are tack-attached to base plate 110.

[0052] 2A-2C show some non-limiting close-up views of a structural member 120 tacked to a base plate 110. In FIG. 2A, the line of contact 200 between the base plate 110 and the structural member 120 and the interrupted edge of the structural member 120 are relatively clear, with the line of contact 200 terminating at point E. Therefore, it is important that the weld plan generated ensures that the weld at the line of contact 200 terminates at point E and does not continue to the edge 111 of the base plate 110. In the embodiment shown in FIG. 2B, a so-called rathole is located in the structural member 120. Such a rathole also interrupts the line of contact 200, preventing the weld seam from continuing along the entire length of the structural member 120. Here, the starting point S of the line of contact 200 coincides with the edge 111 of the base plate 110, and the line of contact 200 terminates at point E on one side of the rathole. The line of contact 200 then continues again from a second point S on the other side of the second rathole. In the embodiment of FIG. 2C, the structural member 120 has a tapered end, also referred to in the art as a "snipe." For such structural members, the origin S of the contact line 200 between the structural member 120 and the base plate 110 must still be clearly recognized. While all of the structural members shown in FIGS. 2A-2C are simple, straight structural members 120, it should be noted that instead of such straight structural members, other structural member shapes, including T-shaped structural members, angled structural members, I-shaped structural members, bulb structural members, and / or bar structural members, can also be recognized by the methods disclosed herein, as will be made clearer below.

[0053] 3 and 4, an overhead gantry 3 is shown above a base plate 110. Referring to the embodiment shown in FIG. 3, a sensor 2 including a laser source 21 and a camera 22 is mounted below the gantry 3, above and directed toward the base plate 110. The laser source 21 is configured to generate a laser beam that moves across the workpiece, e.g., blue, having a wavelength between 450 nm and 500 nm. The camera 22 is configured to record the laser beam as it moves across the workpiece, e.g., to determine the distance (i.e., height) between the laser beam and the camera 22. In the embodiment of FIG. 3, a single camera 22 and a single laser source 21 are provided. For example, the laser beam emitted from the laser source 21 has an arc-shaped shape with a beam angle between 20° and 180°. If the beam angle is in the lower part of that range, e.g., between 20° and 60°, the camera 22 may only be able to see a portion of the width of the base plate 110. Therefore, in such an embodiment, to enable inspection of the entire base plate, the sensor 2 may be movable in a movement direction M1, i.e., the width or lateral direction of the base plate 110. For example, the sensor 2 may move along the length of the base plate 110 once or as many times as necessary, move laterally across the base plate 110, and then move again along the base plate 110. Because the sensor 2 may inspect only one cross-sectional area of ​​the base plate 110 at a time, the sensor 2 may also move in the longitudinal direction M2 of the base plate 110. The movement along the base plate 110 may be, for example, linear and continuous. In other embodiments, it may be advantageous to back off the sensor 2 somewhat at a specific point where more detailed information than the average is needed, and perform a second scan, possibly at a slower speed. Alternatively or additionally, the second scan may be obtained by rotating the sensor 2 180° about an axis perpendicular to the workpiece 100 and returning the gantry to its original position after the first scan of the workpiece 100 is completed.In the embodiment of FIG. 3, a single sensor 2 is provided, including a single laser source 21 and a single camera, positioned in fixed positions relative to each other. As an alternative to FIG. 3, FIG. 4 shows a side cross-sectional view of how the sensor 2, including the laser source 21 and camera 22, is positioned in front of the gantry 3. In particular, the sensor 2 is extended forward relative to the gantry 3 by an extension member 5. As a result of being positioned in front of the gantry, the laser source 21 projects a laser line onto the structural member 120 at an angle of, for example, between 10° and 25° relative to a line perpendicular to the base plate. As will be appreciated by those skilled in the art, the greater the angle between the orientation of the laser source 21 and the line perpendicular to the base plate, the deeper the laser source can see, for example, below the top bar of a T-shaped structural member. However, the greater the angle between the projection of the laser source 21 and the line perpendicular to the base plate, the longer the extension member 5 must be, and the more susceptible to vibrations due to movement that can introduce noise into the measurement results. Applicant has found that an angle between 10° and 25° is optimal in this regard, although this allows for the system not to fit some structural members 120 with very wide upper flanges. Additionally, camera 22 is shown, rigidly attached to laser light source 21 so that the distance between camera 22 and laser light source 21 is fixed. Camera 22 is also positioned at an angle relative to laser light source 21 so that camera 22 captures the light projected by laser light source 21 as shown. It will be appreciated that the exact angle between laser light source 21 and camera 22 depends on the height between gantry 3 and base plate 110. Based on this parameter and the fixed orientation of camera 22 relative to laser light source 21, camera 22, particularly if it is a "range camera," can view the structural member and determine the distance to that structural member. Moving sensor 2 along the base plate as described above can generate a mapping of the base plate.

[0054] As shown in FIG. 5A, when the camera 22 is facing straight down—i.e., the tilt angle β between the vertical and the centerline of the camera 22's field of view is 0°—the camera 22 sees only a very small lower portion 121 of the structural member 120 and does not see the large upper portion 122 of the structural member. This lower portion is too small to reliably detect the contact line between the base plate 110 and the structural member 120. In contrast, as shown in FIG. 5B, when the camera 22 is tilted so that the tilt angle β is in the range of, for example, 10° to 60°, the visible lower portion 121 of the structural member 120 becomes significantly larger. This larger portion 121 allows the position of the contact line, and therefore the weld seam, to be accurately identified. When the camera 22 is positioned at an angle to the laser beam emitted from the laser source 21, the distance between the camera 22 and the laser line can be obtained using a technique called "triangulation."

[0055] 3 and 4, as the laser source 21 and camera 22 move along the workpiece, the sensor 2 measures, for example, the distance between the camera and the laser line projected onto the workpiece. From this distance, the height of the laser line is obtained, which corresponds to the height of the workpiece at that location. For example, once the entire surface of the workpiece has been scanned, these measurements may be stored as data points each identifying a position and height.

[0056] All of the data points can then be mapped as a point cloud using a software program. The result of this mapped point cloud 100'' is shown in FIG. 6A. In this mapping, the base plate 110'' and structural members 120'', 130'' are clearly identifiable. It should be explicitly noted that this image can be acquired without prior computer-rendered information about the workpiece of interest.

[0057] From this collection of data points, representing the local heights of the structural members above the base plate, a 3D representation 100' of the workpiece can be generated. In a particularly advantageous embodiment, this is achieved by fitting planes to the point cloud 100'', the collection of planes defining the 3D representation 100'. A 3D representation obtained by this method from the point cloud 100'' shown in FIG. 6A is shown in FIG. 6B. Advantageously, by fitting planes to the point cloud 100'', the exact location of points for which information is missing can be estimated based on the locations of neighboring points using the plane fitting method. Further advantageously, the individual planes can be described with a relatively small data set, allowing for rapid sharing and export of information about the workpiece while it is being scanned. Again, the 3D representation 100' is obtained without any prior computer-rendered information about it.

[0058] The step of generating the 3D representation 100' of the workpiece may include filtering out irrelevant objects on the base plate, i.e., objects other than the structural members. The step of generating the 3D representation 100' of the workpiece may further include a filtering step to remove reflections and / or noise from the data acquired by the sensor 2. It should be noted that this filtering may be performed solely for the purpose of generating the welding plan. Advantageously, when the movement path of the welding gun is planned, objects that are irrelevant for welding purposes may be crucial to avoid collisions between the welding gun and these objects.

[0059] Once the 3D representation is generated, the weld seams can be relatively easily obtained by identifying the contact lines between the structural member and the base plate, and a welding plan for welding the structural member to the base plate can be derived based on the set of identified weld seams. Thus, a welding plan for a one-piece workpiece can be automatically generated.

[0060] Of course, the above steps may be followed by a step of welding the structural member to the base plate according to a welding plan using a welding torch to obtain a workpiece, preferably performed by a robot or automated welding torch.

[0061] Before starting welding, it may be desirable to closely inspect a particular area of ​​the workpiece, for example to identify the exact start point of the weld seam. For example, this can be done using a distance sensor integrated into the welding torch and / or a touch sensor integrated into the welding torch.

[0062] Measurements may also be taken during the welding process using a distance sensor integrated into the welding torch, for example, in order to determine the end point of the weld seam with greater precision than is possible with a sensor.

Claims

1. A method for automatically generating a welding plan for a workpiece (100), in particular a (quasi-) one-off workpiece (100), comprising: The workpiece (100) comprises a base plate (110) and one or more structural members (120, 130) projecting upwardly from the base plate; A sensor (2) is used, which comprises a laser light source (21) and a camera (22) arranged in fixed positions at an angle of 10° to 60° relative to each other, the laser light source (21) being configured to generate a laser beam, the camera (22) being configured to record the laser beam, and the sensor (2) being movable relative to the workpiece (100), The method comprises: a) moving the sensor (2) over the workpiece (100) while the laser light source (21) emits a laser beam that is projected onto the workpiece (100); b) using said camera (22) to acquire laser line height data representing the local height of a laser line projected onto said workpiece (100); c) generating a 3D representation (100') of the workpiece (100) based on the local height data acquired by the sensor (2) in step b); d) defining a weld seam at a contact line (200) between the structural member (120, 130) and the base plate (110) based on the 3D representation (100') of the workpiece (100); e) generating a welding plan based on the series of weld seams; A method comprising:

2. In step a), the movement of the sensor (2) is in the longitudinal direction of the workpiece (100), The method of claim 1.

3. In step a), the movement of the sensor (2) is in the lateral direction of the workpiece (100); 3. The method according to claim 1 or 2.

4. In step a), the movement is intermittent, and the sensor (2) is configured to move along the forward movement direction and against the forward movement direction while the laser light source (21) is emitting a laser beam to the workpiece (100). The method according to any one of claims 1 to 3.

5. In step a), the movement is a continuous linear movement. The method according to any one of claims 1 to 3.

6. The laser beam emitted from the laser light source (21) has an arc shape with a width between 20° and 180°.

7. The color of the laser light emitted from the laser light source (21) is blue and has a wavelength of, for example, 450 to 500 nm.

7. The method according to any one of claims 1 to 6.

8. In step b), the local height of the laser line is acquired as a point cloud (100'') by the sensor (2), in particular by means of triangulation; 8. The method according to any one of claims 1 to 7.

9. In step c), the point cloud (100'') obtained in step b) is transformed into a 3D representation (100') of the workpiece (100). The method of claim 8.

10. said 3D representation (100') being obtained by fitting a plane, preferably with straight edges, to said point cloud (100''); 10. The method of claim 9.

11. generating the 3D representation (100') of the workpiece (100) includes a filtering step to remove irrelevant objects on the base plate (110), i.e. objects other than the structural members (120, 130), and / or a filtering step to remove reflections and / or noise from the data acquired by the sensor (2); 11. The method according to any one of claims 1 to 10.

12. The structural members (120, 130) disposed on the base plate (110) may include T-structural members, angled structural members, I-structural members, valve structural members, and / or bar structural members, and the structural members may include ratholes (121), tapered edges (122), and / or notches (123) near or within the contact line (200); 12. The method according to any one of claims 1 to 11.

13. A weld seam is further defined at each contact line (300) of the two structural members (120, 130).

13. The method of any one of claims 1 to 12.

14. A method for automatically welding a workpiece (100), comprising: The steps of any one of claims 1 to 13; welding the structural members (120, 130) to the base plate (110) using a welding torch according to a welding plan to obtain the workpiece (100); A method comprising:

15. Between the step of generating the welding plan and the step of welding, detailed measurements are taken to identify the exact start point of the weld seam, for example using a distance sensor integrated into the welding torch.

15. The method of claim 14.

16. During the welding step, detailed measurements are taken, for example using a distance sensor integrated into the welding torch, in order to identify the exact end point of the weld seam.

16. The method of claim 14 or 15.

17. 1. A system for automatically generating a welding plan for a workpiece (100), in particular a (quasi-) one-off workpiece (100), comprising a base plate (110) and one or more profiles (120, 130) projecting upward from said base plate (110), comprising: a laser light source (21) configured to generate a laser beam; a camera (22) arranged at a fixed position relative to the laser light source (21) at an angle of 10° to 60° with respect to the center line of the laser beam emitted from the laser light source (21), and configured to record the laser beam; Equipped with The laser light source (21) and the camera (22) form a sensor (2) arranged above the workpiece (100) and configured to be movable relative to the workpiece (100); further comprising a processor; The processor: calculating laser line height data representing a local height of the laser line projected onto the workpiece based on the recordings provided by the camera; generating a 3D representation (100') of the workpiece (100) based on the local height data; defining a weld seam at a contact line (200) between the structural member (120, 130) and the base plate (110) based on a 3D representation (100') of the workpiece (100); generating a welding plan based on the set of weld seams; configured to perform method.

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