Workpiece measurement method and welding system

Abstract

To provide a workpiece measurement method capable of accurately measuring a configuration of a measurement object while shortening a measurement time of the measurement object compared with conventional methods.SOLUTION: A workpiece measurement method for measuring a workpiece comprising columnar members and diaphragms and held by a positioner, includes: an acquisition step of acquiring point group data of a surface of the workpiece held by the positioner; a detection step of specifying a part where distribution of the point group data is changed in a three-dimensional coordinate system of the positioner and detecting it as a boundary position between the columnar member and the diaphragm; and a derivation step of deriving the number of columnar members and the number of diaphragms constituting the workpiece based on the boundary position detected in the detection step.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a workpiece measurement method and a welding system. [Background technology]

[0002] Conventionally, members to be welded (hereinafter also referred to as "workpieces") are prepared at predetermined positions, and the workpieces are welded using a welding robot. In such cases, for the purpose of automatic welding of the workpieces, it is required to easily grasp the shape and installation state of the workpieces and to reduce labor. When grasping the position of the workpiece, for example, point cloud data acquired by a ToF (Time of Flight) sensor is used.

[0003] For example, as an example of measuring the dimensions of a workpiece in a welding system, Patent Document 1 discloses a configuration in which a measurement program is selected according to the shape of the measurement target, and measurement is performed by a sensor attached to a welding robot. Also, as an example of measuring a measurement target, Patent Document 2 discloses a configuration in which three-dimensional data of a measurement target placed on a glass table is measured by a laser measurement device, and the three-dimensional shape of the entire measurement target viewed from multiple viewpoints is obtained. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-162554 A [Patent Document 2] JP 2010-276485 A Summary of the Invention [Problem to be solved by the invention]

[0005] For example, in the method of Patent Document 1, it is assumed that a touch sensor or the like is used as a sensor. In this case, when the sensor is operated according to the measurement program, if the distance between the measurement start position by the sensor and the actual installation position of the measurement target is far, a wasteful measurement operation occurs, and the measurement takes time. In addition, in Patent Document 1, it is necessary to switch the measurement program according to the shape of the measurement target, and the measurement program selection must be done manually. In addition, if there is an installation error of the workpiece in the positioner, there is a possibility that an incorrect dimension will be measured. On the other hand, in the configuration of Patent Document 2, a large number of sensors are required, so the cost of the device becomes high, and there is a concern that the device will become large in size.

[0006] An object of the present invention is to enable accurate measurement of the configuration of a measurement target while shortening the measurement time of the measurement target compared to the conventional art. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration. That is, a workpiece measurement method for measuring a workpiece that is constituted by a columnar member and a diaphragm and is held by a positioner includes the following steps: an acquisition step of acquiring point cloud data of the surface of the workpiece held by the positioner, the point cloud data being photographed from a predetermined direction; a detection step of identifying a portion where the distribution of the point cloud data changes in a three-dimensional coordinate system of the positioner and detecting the portion as a boundary position between the columnar member and the diaphragm; a deriving step of deriving the number of the columnar members and the diaphragms constituting the workpiece based on the boundary position detected in the detecting step; has.

[0008] Another aspect of the present invention has the following configuration. That is, a welding system comprising: A welding robot having a welding torch; A welding control device that controls the welding robot; a positioner for holding a workpiece, the positioner being configured with a columnar member and a diaphragm; A sensor that captures an image of the workpiece from a predetermined direction to acquire point cloud data; Equipped with The welding control device includes: an acquisition means for acquiring point cloud data of the surface of the workpiece held by the positioner, the point cloud data being captured by the sensor from the predetermined direction; a detection means for identifying a portion where the distribution of the point cloud data changes in a three-dimensional coordinate system of the positioner and detecting the portion as a boundary position between the columnar member and the diaphragm; a calculation means for calculating a dimension and a position of the workpiece based on the boundary position detected by the detection means; has. Effect of the Invention

[0009] According to the present invention, it is possible to measure the configuration of a measurement target with high accuracy while shortening the measurement time of the measurement target compared to the conventional art. [Brief description of the drawings]

[0010] [Figure 1] 1 is an external perspective view showing an overall outline of a welding system according to an embodiment of the present invention; [Diagram 2] 1 is an external perspective view showing an example of the configuration of a workpiece to be measured according to an embodiment of the present invention; [Diagram 3] 1 is a block diagram showing an example of the configuration of a welding control device according to an embodiment of the present invention; [Figure 4] FIG. 2 is a block diagram showing an example of a functional configuration of a welding control device according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram for explaining a configuration example of a workpiece according to an embodiment of the present invention. [Figure 6] FIG. 2 is a schematic diagram for explaining measurement of a workpiece according to an embodiment of the present invention. [Figure 7A] FIG. 4 is a graph showing an example of a measurement result of a workpiece according to an embodiment of the present invention. [Figure 7B]FIG. 4 is a graph showing an example of a measurement result of a workpiece according to an embodiment of the present invention. [Figure 8A] 5 is a schematic diagram for explaining correction of a workpiece placement error according to an embodiment of the present invention. FIG. [Figure 8B] 5 is a schematic diagram for explaining correction of a workpiece placement error according to an embodiment of the present invention. FIG. [Figure 9] 3 is a flow chart of a welding process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiment for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention, and is not intended to be interpreted as limiting the present invention, and all configurations described in each embodiment are not necessarily essential configurations for solving the problems of the present invention. Also, in each drawing, the same components are given the same reference numbers to indicate their correspondence. Note that in this embodiment, the expressions "first" and "second" are merely used to distinguish from other elements, and are not intended to be interpreted as specific elements in a limiting manner. Therefore, these expressions should be interpreted appropriately depending on the combination and number of components.

[0012] <First embodiment> Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0013] [Welding system configuration] 1 is an external perspective view showing an overview of a welding system 100 to which a workpiece measurement method according to this embodiment can be applied. The welding system 100 includes a welding device 1, a positioner 2, a welding robot 3, a welding control device 8, a controller 9, and a camera 10 (first sensor).

[0014] Welding device 1 is configured to weld workpiece W held by positioner 2 using welding robot 3. Welding control device 8 controls welding robot 3 via controller 9. At this time, welding control device 8 may further control moving means 11, 12 to control the relative position of welding robot 3 and workpiece W. Welding control device 8 also controls the rotational operation of positioner 2 and the shooting operation of camera 10. Note that, although this embodiment will be described as welding control device 8 comprehensively performing control related to welding, a configuration in which separate control devices are provided for each device and these control devices perform welding in cooperation with each other may also be used.

[0015] As shown in Fig. 2, the workpiece W according to this embodiment is composed of a column 21 and a diaphragm 22. The workpiece W is held by a positioner 2 and is installed so as to be rotatable around a predetermined axis. The positioner 2 is a face plate that holds the workpiece W and fixes it in the axial direction. The positioner 2 also includes a rotation drive unit that rotates the workpiece W in the circumferential direction. Note that while Fig. 1 shows a cantilever positioner 2 that holds one end of the workpiece W, a double-support positioner that holds both ends of the workpiece W may also be used.

[0016] The welding robot 3 is configured to have various functions for welding various weld joints of the workpiece W held by the positioner 2. For example, an arc welding robot may be used as the welding robot 3. The welding robot 3 includes a multi-joint arm 4, a welding torch 5 supported by the arm 4, a welding wire 6 fed to the tip of the welding torch 5, and a sensor 7 (second sensor) capable of detecting the position of the tip of the welding torch 5.

[0017] The sensor 7 is provided around the tip of the welding robot 3, and measures the coordinates of a preset detection position on the workpiece W as measurement data by moving the welding robot 3. The sensor 7 may be any sensor capable of measuring the coordinates of the workpiece W as measurement data, and may be a non-contact position detection sensor such as a laser, or a contact position detection sensor such as a touch sensor. In this embodiment, the sensor 7 is described as providing a touch sensing function for grasping the position and shape of the workpiece W. The measurement data measured by the sensor 7 may include coordinate information at a position other than the detection position.

[0018] Controller 9 controls welding robot 3 according to a predefined measurement program and welding program. Specifically, welding robot 3 is moved based on the measurement program, and sensor 7 provided on welding robot 3 measures coordinates of a detection position on workpiece W as measurement data. Furthermore, welding robot 3 is moved based on the welding program, thereby welding workpiece W. The measurement program and welding program are provided by welding control device 8.

[0019] The camera 10 is used to photograph the workpiece W before welding and to identify the shape, dimensions, position, etc. of the workpiece W. The camera 10 is configured to be capable of acquiring point cloud data of the surface of the workpiece W as three-dimensional data. For example, a ToF (Time of Flight) camera, a stereo camera, or a LiDAR (Light Detection and Ranging) sensor can be used as the camera 10. Since each of the above sensors has different characteristics, they may be used according to the measurement environment and the workpiece W to be measured. In this embodiment, the camera 10 is installed above the workpiece W and the positioner 2 and is configured to be able to photograph the workpiece W located below. Note that the installation position and photographing direction of the camera 10 are not limited to this, and may be set arbitrarily in accordance with the rotation axis of the workpiece W by the positioner 2.

[0020] A ToF camera that can be used as the camera 10 irradiates a measurement target with laser light and measures the reflected laser light with an imaging element to calculate the distance for each pixel. The measurable distance of a ToF camera is about tens of centimeters to several meters. A stereo camera uses multiple images taken by multiple cameras (for example, two cameras) to calculate the distance from their parallax. The measurable distance of a stereo camera is about tens of centimeters to several meters. A LiDAR calculates the distance by irradiating a laser light to the surroundings and measuring the reflected laser light. The measurable distance of a LiDAR is about tens of centimeters to several meters.

[0021] The moving means 11, 12 move the welding robot 3 in at least one direction parallel to and perpendicular to the rotation axis direction of the workpiece W held by the positioner 2. Specifically, a cart may be used as the moving means 11, and a rail may be used as the moving means 12. The moving means 12 travels along the moving means 11 parallel to the rotation axis of the positioner 2, thereby moving the welding robot 3 placed on the moving means 12 parallel to the axial direction of the workpiece W. In addition, by configuring the moving means 12 to be movable in a direction perpendicular to the moving means 11, the welding robot 3 placed on the moving means 12 is moved in a direction perpendicular to the axial direction of the workpiece W.

[0022] In this embodiment, three three-dimensional coordinate systems are used: a robot coordinate system which is the coordinate system of the welding robot 3, a positioner coordinate system which is the coordinate system of the positioner 2, and a camera coordinate system which is the coordinate system of the camera 10. These coordinate systems are assumed to correspond to each other so that coordinate values ​​can be converted. Furthermore, each coordinate system may be defined relatively to one of them as a reference, or each may be defined in an absolute coordinate system. In the following description, when a specific coordinate system is referred to, a specific coordinate system will be shown.

[0023] (Work) FIG. 2 is an external perspective view showing an example of the configuration of the workpiece W, which is the measurement target according to this embodiment. A camera 10 is disposed above the workpiece W, making it possible to acquire point cloud data of the surface of the workpiece W. The workpiece W is composed of one column 21 and two diaphragms 22 disposed on both sides thereof. The column 21 may be a columnar member having a square tubular shape (e.g., a square steel pipe) or a cylindrical shape (e.g., a circular steel pipe). The outer periphery of the column 21 is configured to include a flat portion or a curved portion having a certain curvature, depending on the shape. The curvature of the curved portion is not particularly limited.

[0024] In FIG. 2, the length of the column 21 is indicated by L, and the diameter is indicated by H. The diaphragm 22 is, for example, rectangular. In addition, P0 to P6 shown in FIG. 2 indicate examples of position coordinates extracted from the measurement data. In the workpiece W, the extracted position coordinates are not particularly limited. In addition, the shape of the workpiece W is not limited to the one-stage core configuration as shown in FIG. 2. For example, it may be a two-stage core configuration consisting of two columns and three diaphragms installed between them and at both ends. Note that, when the workpiece W has a two-stage core configuration, the position of the camera 10 may be adjusted according to its shooting range, and point cloud data of the entire workpiece W may be obtained by shooting multiple times. In addition, a groove 23 of a predetermined shape is formed at the connection part between the column 21 and the diaphragm 22.

[0025] (Welding control device) 3 is a block diagram showing an example of the configuration of welding control device 8 according to this embodiment. Welding control device 8 may be formed from an information processing device such as a PC (Personal Computer). Welding control device 8 includes a control unit 301, a storage unit 302, an IF (Interface) unit 303, a communication unit 304, and a UI (User Interface) unit 305.

[0026] The control unit 301 may be configured using at least one of a central processing unit (CPU), a graphical processing unit (GPU), a micro processing unit (MPU), a digital signal processor (DSP), or a field programmable gate array (FPGA). The storage unit 302 is configured by a volatile or non-volatile storage device such as a hard disk drive (HDD), a read only memory (ROM), or a random access memory (RAM). The control unit 301 reads out and executes various programs stored in the storage unit 302 to realize various functions described below.

[0027] The IF unit 303 is an interface for connection to an external device and controls transmission and reception with the external device. The IF unit 303 is connected to, for example, the controller 9, the positioner 2, and the like.

[0028] The communication unit 304 is a unit for communicating with external devices and various sensors. The communication by the communication unit 304 may be wired or wireless, and the communication standard is not limited. The UI unit 305 receives operations from a user and displays measurement results. The UI unit 305 may include, for example, a mouse and a keyboard (not shown), or may be configured as a touch panel display in which a display unit and an operation unit are integrated. Each unit in the welding control device 8 is connected to each other so as to be able to communicate with each other via an internal bus (not shown) or the like.

[0029] [Function configuration] Fig. 4 shows an example of the functional configuration of welding control device 8 according to this embodiment. Each part shown in Fig. 4 may be realized by control unit 301 of welding control device 8 reading and executing a program stored in storage unit 302. Note that the configuration shown in Fig. 4 is an example, and one part may be configured as multiple parts, or multiple parts may be configured together as one part. Furthermore, when multiple control devices cooperate with each other to perform welding in welding system 100, each part shown in Fig. 4 may be arranged in a corresponding control device according to the configuration.

[0030] The data acquisition unit 401 acquires point cloud data of the workpiece W, which is the measurement target, via the camera 10. The data acquisition unit 401 also acquires various data measured by a touch sensing function using the sensor 7 provided at the tip of the welding robot 3. The data mode control unit 402 controls the operation mode in the welding system 100. For example, mode and parameter control related to the measurement of the workpiece W performed before welding, mode and parameter control during welding, etc. may be performed.

[0031] The preprocessing unit 403 performs preprocessing on the acquired point cloud data. The preprocessing here may vary depending on the point cloud data to be used, and may include, for example, filtering, outlier removal, clustering, coordinate conversion, etc. The program generating unit 404 generates a program appropriate for the workpiece W to be welded by modifying a pre-stored welding program or sensing program with general-purpose content based on the measurement results.

[0032] The estimation processing unit 405 performs processing to estimate the shape of the workpiece W using the acquired point cloud data. Details of the estimation processing will be described later. The estimation result holding unit 406 holds the shape and position of the workpiece W estimated by the estimation processing of the estimation processing unit 405 as estimation results. The data management unit 407 holds predefined information on the workpiece W and data related to the welding operation.

[0033] The sensing program storage unit 408 stores a sensing program for sensing performed using the sensor 7 installed at the tip of the welding robot 3. The welding program storage unit 409 stores a welding program used when welding is performed using the welding robot 3.

[0034] The robot control unit 410 uses a welding program and a sensing program to control the welding robot 3 via the controller 9 and executes various operations. The robot control unit 410 may be configured to also control the moving means 11, 12. The positioner control unit 411 uses a welding program and a sensing program to control the positioner 2 holding the workpiece W and executes rotation operations and the like. The camera control unit 412 controls the measurement operation by the camera 10.

[0035] [Measurement example] An example of the measurement of the workpiece W according to this embodiment will be described with reference to Figs. 5 to 8B. Fig. 5 is an external view of the workpiece W. The coordinate axes shown in Fig. 5 have different origins, but their orientations correspond to the positioner coordinate system in the positioner 2. As described with reference to Fig. 2, the workpiece W is composed of a column 21 and a diaphragm 22. At this time, the region R in Fig. 5 is a curved surface, and depending on the shooting orientation of the camera 10, the shape may not be accurately acquired as point cloud data. Therefore, for example, as shown by the length 1, there is a concern that the dimension of the workpiece W may be detected as shorter than it actually is. In this embodiment, the workpiece W is configured to be capable of being measured in response to such a configuration of the workpiece W.

[0036] 6 shows the workpiece W as viewed from the side along the x-axis direction. The coordinate system shown superimposed on the workpiece W is the positioner coordinate system, and the positioner 2 holds the workpiece W in the horizontal direction as shown in FIG. 1. Here, it is assumed that the z-axis of the positioner coordinate system coincides with the rotation axis of the positioner 2. Also, it is assumed that the camera 10 captures the workpiece W along the y-axis direction.

[0037] In FIG. 6, the length L indicates the length of the column 21 in the z-axis direction, and the diameter H indicates the radius of the column 21. The point cloud data Pd indicates the point cloud data indicating the outer shape of the workpiece W acquired by the camera 10, projected onto the yz plane. P2 and P3 indicate the connection position between the diaphragm 22 and the column 21 shown in FIG. 2. As shown in P2 and P3, when viewed on the yz plane, the connection position between the diaphragm 22 and the column 21 can be captured as a change point of the point cloud data where the distribution of the point cloud data changes in a predetermined direction. Therefore, the diameter H of the column 21 can be derived based on the value of the y coordinate of the positioner coordinate system. Furthermore, the length L of the column 21 can be derived based on the values ​​of the y coordinate and z coordinate of the positioner coordinate system. Furthermore, the length of the diaphragm 22 in the z-axis direction, i.e., the plate thickness, can also be derived based on the values ​​of the y coordinate and z coordinate of the positioner coordinate system.

[0038] 7A shows an example of point cloud data when measuring the workpiece W. In Fig. 7A, the horizontal axis indicates the z coordinate value in the positioner coordinate system, and the vertical axis indicates the y coordinate value in the positioner coordinate system. The origin of the z coordinate corresponds to the holding position of the workpiece W by the positioner 2.

[0039] A solid line 700 is a position coordinate of the surface of the workpiece W estimated from the point cloud data. P2 and P3 of the workpiece W are actual connection positions of the column 21 and the diaphragm 22. As measured in FIG. 7A, a groove exists at the connection position of the column 21 and the diaphragm 22 before welding. The solid line 700 can be obtained by using, for example, a Fused Lasso change point detection method. In this solid line 700, for example, a point that is away from the minimum value of the Y coordinate by a predetermined threshold value can be set as a change point. In the example shown in FIG. 7A, points that are away from the minimum value of the Y coordinate by a predetermined threshold value are detected at the positions of P2 and P3.

[0040] FIG. 7B shows an example of point cloud data when measuring a two-stage core workpiece. In FIG. 7B, the horizontal axis indicates the z-coordinate value in the positioner coordinate system, and the vertical axis indicates the y-coordinate value in the positioner coordinate system. The origin of the z-coordinate corresponds to the holding position of the workpiece W by the positioner 2. The solid line 800 is the position coordinate of the surface of the workpiece estimated from the point cloud data. P1' to P4' indicate the actual connection positions of the column and the diaphragm. As shown in FIG. 7A and FIG. 7B, the number of components of the workpiece W, that is, the number of columns and the number of diaphragms, can also be derived by capturing the change points of the point cloud data corresponding to the connection positions of the columns and the diaphragms, that is, the parts where the distribution of the point cloud data changes.

[0041] Here, a description will be given of how the positioner 2 according to this embodiment deals with an installation error of the workpiece W. Assume that the holding position of the workpiece W by the positioner 2 is deviated from the rotation axis of the positioner 2. In this case, as shown in FIG. 8A, the central axis C of the column 21 and the rotation axis (corresponding to the z-axis) of the positioner 2 are misaligned. As a result, a deviation occurs in the measurement value of the diameter of the column 21. In the example of FIG. 8A, the installation error h err In this case, the actual diameter of column 21 is (h+h err )

[0042] In this embodiment, taking into consideration such installation errors of the positioner 2, measurements are performed multiple times while rotating the positioner 2. Then, the installation errors are corrected based on the results of the multiple measurements.

[0043] FIG. 8B is a diagram for explaining the concept of correcting the installation error. Here, the central axis C of the column 21 and the rotation axis (corresponding to the z-axis) of the positioner 2 are misaligned. Pd1 is point cloud data obtained in the first measurement. Based on this point cloud data Pd1, h1 is obtained as the diameter of the column 21, and a value different from the actual value is obtained due to the installation error. In response to this, the positioner 2 rotates the workpiece W 180 degrees along the rotation axis (corresponding to the z-axis) and performs measurement again. As a result, Pd2 is obtained as the point cloud data. Based on this point cloud data Pd2, h2 is obtained as the diameter of the column 21.

[0044] In this embodiment, the values ​​obtained as a result of these multiple measurements are averaged to correct the installation error. Therefore, the diameter H of the column 21 from which the effects of the installation error have been removed can be calculated by H=(h1+h2) / 2. Note that other rotation angles may be used taking into account the direction of the installation error. For example, the rotation angle of the positioner 2 may be 90 degrees or 270 degrees. Also, the number of measurements is not limited to two, and more measurements may be performed taking into account the measurement accuracy, etc.

[0045] The point cloud data obtained by the camera 10 makes it possible to specify the approximate dimensions and installation positions of each part constituting the workpiece W. Based on this result, the welding robot 3 can be moved closer to the periphery of the workpiece W. During welding, it is advisable to perform position control of the tip of the welding torch 5 with higher accuracy. For this reason, more precise position detection is performed by touch sensing using the sensor 7 provided at the tip of the welding torch 5. In other words, the point cloud data obtained by the camera 10 makes it possible to estimate the dimensions and installation position of the workpiece W with a certain degree of accuracy, move the workpiece W to its vicinity, and adjust the start position of touch sensing. For this reason, the time required for the touch sensing operation by the sensor 7 can be reduced.

[0046] Then, after estimating the dimensions and installation position of the workpiece W with a certain degree of accuracy by the method using the point cloud data described above, it is possible to precisely measure the area R, the groove, and other parts by the touch sensing operation of the sensor 7, and correct the dimensions and installation position of the workpiece W. This makes it possible to accurately identify the welding position on the workpiece W, and to automate more precise welding.

[0047] [Processing flow] The flow of welding including the workpiece measurement process according to this embodiment will be described below. Fig. 9 is a flowchart showing the overall flow of welding including the workpiece measurement process according to this embodiment. Each process is realized by the welding control device 8 shown in Fig. 1 controlling each part of the welding system 100. Here, to simplify the description, the processing subject will be collectively described as the welding control device 8. Before this processing flow is started, the workpiece W is held by the positioner 2 and placed in a position where it can be photographed by the camera 10.

[0048] In step S901, welding control device 8 sets a measurement mode. The measurement mode here may be based on a mode designated by a user, or may be a mode defined in advance. In the measurement mode, for example, a mode in which measurement is performed multiple times by changing the rotation angle of positioner 2 as described above, and a mode in which measurement is performed only once may be designated.

[0049] In step S902, the welding control device 8 photographs the workpiece W using the camera 10 and acquires point cloud data. If the workpiece W is smaller than a predetermined dimension, the point cloud data may be acquired in one photographing operation. If the workpiece W is larger than a predetermined dimension, multiple point cloud data may be acquired by multiple photographing operations and integrated. In this process, when photographing, the welding control device 8 may be configured to adjust the photographing range and photographing angle depending on the position of the positioner 2, or may be specified depending on the measurement mode set in step S901.

[0050] In step S903, the welding control device 8 performs pre-processing on the point cloud data acquired in step S902. Examples of the pre-processing include filtering, outlier removal, clustering, coordinate conversion, etc. Note that the pre-processing in this step may be omitted as long as it is performed according to the configuration of the point cloud data acquired in step S902.

[0051] The filter process may be a process of making the point cloud density per a predetermined volume constant by resampling the point cloud included in the point cloud data at a certain interval using, for example, a known Voxel Grid filter. The outlier removal process may be a process of removing outliers that may reduce the measurement accuracy. The outlier may be identified, for example, from statistical information such as the average and variance of adjacent point clouds, or from the number of adjacent point clouds existing within a certain radius. The clustering process may be a process of removing point clouds other than the point cloud indicating the shape of the workpiece W by dividing the point clouds included in the point cloud data into multiple groups based on distance, etc., and deleting groups whose number of point clouds belonging to the group is equal to or less than a certain threshold. The coordinate conversion process converts from the camera coordinate system of the camera 10 to a predetermined coordinate system based on the shooting position and shooting angle of the camera 10. The predetermined coordinate system may be, for example, the positioner coordinate system of the positioner 2. Parameters required for the conversion of the coordinate system may be derived in advance by a calibration process or the like.

[0052] In step S904, the welding control device 8 uses the point cloud data processed in step S903 to perform an estimation process of the dimensions and shape of the workpiece W. The estimation process here may include estimation of the installation position of the workpiece W and the number of columns 21 and diaphragms 22 that constitute the workpiece W. In this embodiment, as shown in Fig. 6, the length L and diameter H of the column are estimated.

[0053] As shown in FIG. 5, the column 21 constituting the work W may have a region R having a certain curvature. When the column 21 is cylindrical (for example, a circular steel pipe), the region R becomes wider. Therefore, in the present embodiment, in the xz plane of the positioner coordinate system, point cloud data only in the vicinity of the center of the column 21 is extracted. In the present embodiment, the zy plane is a horizontal plane and is orthogonal to the shooting direction of the camera 10. As the vicinity of the center of the work W here, for example, when the positioner coordinate system is assumed as shown in FIG. 6, in the x-axis direction, it may be in the range of -50 mm < x < 50 mm. This range may be changed according to the size and shape of the work W to be measured, the setting of the positioner coordinate system (that is, the installation position of the work W in the positioner 2), and the like. As the point cloud data for that region, data as shown in FIG. 7A can be acquired.

[0054] In step S905, the welding control device 8 determines whether the measurement has been completed. For example, it may be determined based on whether the number of measurement times defined based on the mode set in step S901 has been executed. Alternatively, an operation from the user may be received, and it may be determined that the measurement is completed based on that operation. When the measurement is completed (YES in step S905), the process of the welding control device 8 proceeds to step S907. On the other hand, when the measurement is not completed (NO in step S905), the process of the welding control device 8 proceeds to step S906.

[0055] In step S906, the welding control device 8 causes the positioner 2 to perform rotation control at a preset rotation angle. The rotation angle here may be defined according to the mode set in step S901, for example. Specifically, when the first rotation angle is 0 degrees around the z-axis of the positioner coordinate system, 180 degrees, 90 degrees, 270 degrees, etc. may be appropriately used. After that, the process of the welding control device 8 returns to step S902 and the process is repeated.

[0056] In step S907, the welding control device 8 corrects the estimation result and calculates the installation error. Specifically, the correction and calculation are performed as described with reference to FIG. 8B. This step may be executed when the workpiece W is rotated by the positioner 2 and measurements are performed multiple times. Therefore, this step may be omitted when measurements are performed only once. Also, the processing to be executed may be switched depending on the measurement result.

[0057] In step S908, the welding control device 8 generates a touch-sensing program based on the estimation result. The touch-sensing program is predefined with general-purpose content. Then, the touch-sensing program is generated by adjusting parameters for the workpiece W based on the dimensions and installation position of the workpiece W according to the estimation result.

[0058] In step S909, the welding control device 8 operates the welding robot 3 and the like based on the touch sensing program generated in step S908, and measures the dimensions and position of the workpiece W more precisely using the sensor 7 installed at the tip of the welding robot 3.

[0059] In step S910, welding control device 8 generates a welding program based on the dimensions and position of workpiece W measured in step S909. The welding program is defined in advance with general content. Then, the welding program is generated by adjusting parameters for workpiece W based on the more precise dimensions and installation position of workpiece W obtained from the measurement results.

[0060] In step S911, welding control device 8 operates welding robot 3 and the like based on the welding program generated in step S910 to perform welding on workpiece W. Then, after welding is completed, this process flow ends.

[0061] As described above, according to the present embodiment, it is possible to accurately measure the configuration of the measurement target while shortening the measurement time of the measurement target compared to the conventional method. In particular, the number and positions of columns and diaphragms that constitute the workpiece can be easily estimated with a certain degree of accuracy, and the time required to operate the welding robot for measurement can be shortened.

[0062] <Other embodiments> This embodiment can also be realized by supplying a program or application for realizing the functions of one or more of the above-mentioned embodiments to a system or device via a network or a storage medium, and having one or more processors in a computer of the system or device read and execute the program.

[0063] The present embodiment may be realized by a circuit that realizes one or more functions, such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[0064] As described above, the present specification discloses the following: (1) A method for measuring a workpiece (e.g., workpiece W) that is comprised of a columnar member (e.g., column 21) and a diaphragm (e.g., diaphragm 22) and is held by a positioner (e.g., positioner 2), comprising: An acquisition step of acquiring point cloud data of the surface of the workpiece held by the positioner, the point cloud data being captured along a predetermined direction (e.g., the y-axis direction of the positioner coordinate system); a detection step of identifying a portion where the distribution of the point cloud data changes in a three-dimensional coordinate system of the positioner and detecting the portion as a boundary position (e.g., P2, P3) between the columnar member and the diaphragm; a deriving step of deriving the number of the columnar members and the diaphragms constituting the workpiece based on the boundary position detected in the detecting step; A workpiece measuring method comprising the steps of: According to this configuration, it is possible to measure the configuration of the measurement target with high accuracy while shortening the measurement time of the measurement target compared to the conventional method. In particular, the number and positions of columns and diaphragms that constitute the workpiece can be easily estimated with a certain degree of accuracy, and the time required to operate the welding robot for measurement can be shortened.

[0065] (2) A work measurement method as described in (1), characterized in that in the detection process, the point cloud data is projected onto a plane (yz plane) represented by a first axis corresponding to the specified direction (e.g., the y axis of a positioner coordinate system) and a second axis perpendicular to the first axis (e.g., the z axis of a positioner coordinate system) and is parallel to the specified direction, and a change point of the point cloud data is detected as a boundary position between the columnar member and the diaphragm. According to this configuration, it is possible to measure the configuration of the measurement target with high accuracy while shortening the measurement time of the measurement target compared to the conventional method. In particular, it is possible to measure the workpiece based on the holding position of the workpiece by the positioner.

[0066] (3) A work measurement method as described in (2), further comprising a calculation step of calculating the dimensions and position of the work based on the boundary position detected in the detection step. According to this configuration, the size and position of the workpiece can be determined with a certain degree of accuracy before the welding robot is operated to perform measurement, and the start position of the measurement using the welding robot can be adjusted based on the result, which makes it possible to shorten the measurement time using the sensor installed in the welding robot.

[0067] (4) A work measurement method as described in (3), characterized in that in the calculation process, at least one of the diameter and length of a columnar member constituting the work and the plate thickness of the diaphragm is calculated. According to this configuration, it is possible to measure the dimensions of the column and diaphragm that constitute the workpiece before operating the welding robot to perform measurements.

[0068] (5) In the acquiring step, a plurality of point cloud data are acquired by rotating the workpiece around the second axis by a predetermined rotation angle using the positioner; The workpiece measuring method according to (3), wherein in the calculation step, dimensions and position of the workpiece are calculated based on the plurality of point cloud data. According to this configuration, it is possible to perform more accurate measurements by taking into account the installation error of the workpiece relative to the positioner.

[0069] (6) A workpiece measurement method as described in (2), wherein in the detection process, the boundary position is detected using point cloud data within a predetermined range from the center in the third axis direction among point cloud data represented by the second axis and a third axis (e.g., the x-axis of a positioner coordinate system) perpendicular to the first axis and the second axis and projected onto a plane (e.g., an xz plane) perpendicular to the predetermined direction. With this configuration, it is possible to remove point cloud data from areas where measurement accuracy would decrease depending on the sensor configuration, and to more accurately derive the workpiece configuration.

[0070] (7) A work measurement method according to (3), further comprising a correction step of correcting at least one of the dimensions or position of the work calculated in the calculation step by sensing. According to this configuration, in the welding system, it becomes possible to perform correction by more accurate sensing based on roughly obtained measurement results.

[0071] (8) a welding robot (e.g., welding robot 3) having a welding torch (e.g., welding torch 5); A welding control device (e.g., welding control device 8) that controls the welding robot; A positioner (e.g., positioner 2) that holds a workpiece (e.g., workpiece W) composed of a columnar member (e.g., column 21) and a diaphragm (e.g., diaphragm 22); A sensor (e.g., a camera 10) that photographs the workpiece from a predetermined direction to acquire point cloud data; A welding system (e.g., welding system 100) comprising: The welding control device includes: An acquisition unit (e.g., a control unit 301, an IF unit 303, a data acquisition unit 401) that acquires point cloud data of the surface of the work held by the positioner, the point cloud data being captured by the sensor from the predetermined direction; A detection means (e.g., the control unit 301, the estimation processing unit 405) that identifies a portion where the distribution of the point cloud data changes in the three-dimensional coordinate system of the positioner and detects it as a boundary position between the columnar member and the diaphragm; A calculation means (e.g., a control unit 301, an estimation processing unit 405) that calculates the dimensions and position of the workpiece based on the boundary position detected by the detection means; A welding system comprising: According to this configuration, it is possible to measure the configuration of the measurement target with high accuracy while shortening the measurement time of the measurement target compared to the conventional method.

[0072] (9) The welding system described in (8) is characterized in that the welding torch has a second sensor (e.g., sensor 7), and the welding control device has a correction means (e.g., control unit 301, program generation unit 404) that corrects at least one of the dimensions or position of the workpiece calculated by the calculation means by sensing with the second sensor. According to this configuration, the size and position of the workpiece can be determined with a certain degree of accuracy before the welding robot is operated to perform measurement, and the start position of the measurement using the welding robot can be adjusted based on the result, which makes it possible to shorten the measurement time using the sensor installed in the welding robot. [Explanation of symbols]

[0073] 1...Welding equipment 2. Positioner 3…Welding robot 4. Arm 5. Welding torch 6…Welding wire 7…Sensor 8…Welding control device 9. Controller 10. Camera 11, 12...Transportation 21…Column 22…Diaphragm 23…Bevel 100…Welding system W…Work

Claims

1. A workpiece measurement method for measuring a workpiece held by a positioner, the workpiece being constituted by a columnar member and a diaphragm, comprising: an acquisition step of acquiring point cloud data of the surface of the workpiece held by the positioner, the point cloud data being photographed from a predetermined direction; a detection step of identifying a portion where the distribution of the point cloud data changes in a three-dimensional coordinate system of the positioner and detecting the portion as a boundary position between the columnar member and the diaphragm; a deriving step of deriving the number of the columnar members and the diaphragms constituting the workpiece based on the boundary position detected in the detecting step; A workpiece measuring method comprising the steps of:

2. The workpiece measurement method according to claim 1, characterized in that in the detection process, the point cloud data is projected onto a plane represented by a first axis corresponding to the specified direction and a second axis perpendicular to the first axis and parallel to the specified direction, and a change point of the point cloud data is detected as a boundary position between the columnar member and the diaphragm.

3. 3. The workpiece measuring method according to claim 2, further comprising a calculation step of calculating dimensions and a position of the workpiece based on the boundary position detected in the detection step.

4. 4. The workpiece measuring method according to claim 3, wherein in the calculation step, at least one of a diameter and a length of a columnar member constituting the workpiece and a plate thickness of the diaphragm is calculated.

5. In the acquiring step, a plurality of point cloud data are acquired by rotating the workpiece around the second axis by a predetermined rotation angle using the positioner; The workpiece measuring method according to claim 3 , wherein in the calculating step, dimensions and a position of the workpiece are calculated based on the plurality of point cloud data.

6. 3. The workpiece measuring method according to claim 2, wherein in the detection step, the boundary position is detected using point cloud data within a predetermined range from a center in the third axial direction among point cloud data represented by the second axis and a third axis perpendicular to the first axis and the second axis and projected onto a plane perpendicular to the predetermined direction.

7. 4. The workpiece measuring method according to claim 3, further comprising a correction step of correcting at least one of the dimensions and the position of the workpiece calculated in the calculation step by sensing.

8. A welding robot having a welding torch; A welding control device that controls the welding robot; a positioner for holding a workpiece, the positioner being configured with a columnar member and a diaphragm; A sensor that captures an image of the workpiece from a predetermined direction to acquire point cloud data; A welding system comprising: The welding control device includes: an acquisition means for acquiring point cloud data of the surface of the workpiece held by the positioner, the point cloud data being captured by the sensor from the predetermined direction; a detection means for identifying a portion where the distribution of the point cloud data changes in a three-dimensional coordinate system of the positioner and detecting the portion as a boundary position between the columnar member and the diaphragm; a calculation means for calculating a dimension and a position of the workpiece based on the boundary position detected by the detection means; A welding system comprising:

9. the welding torch having a second sensor; 9. The welding system according to claim 8, wherein the welding control device further comprises a correcting means for correcting at least one of the size and the position of the workpiece calculated by the calculating means through sensing by the second sensor.

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