High-precision workpiece calibration method and robot

Abstract

The present application relates to a high-precision workpiece calibration method and workpiece calibration system, and relates to the field of robot processing measurement. The method includes: obtaining approximate coordinates corresponding to the target workpiece; determining the hole features, body features, and surface features corresponding to the target workpiece based on the approximate coordinates; determining the hole coordinate system, body coordinate system, and surface coordinate system corresponding to the target workpiece based on the hole features; generating a combined coordinate system according to a combined calibration strategy; and measuring and calibrating the target workpiece based on the combined coordinate system. In the process of calibrating the target workpiece, the combined coordinate system is generated after referring to the multi-dimensional features and calibration is performed based on the combined coordinate system, thereby reducing the cost of the calibration process while ensuring calibration accuracy.

Description

Technical Field

[0001] The present application relates to the field of robot machining measurement, and in particular to a high-precision workpiece calibration method and robot. Background Art

[0002] Robotic machining technology holds broad application prospects in the manufacturing of large, complex components in fields such as aviation, aerospace, high-speed rail, and wind power. Compared to traditional manufacturing, large, complex components are characterized by large size, high precision, small batch sizes, a wide variety of products, complex structures, and demanding operating conditions. Robotic machining of large, complex parts is typically performed offline using a workpiece coordinate system. The calibration accuracy of the workpiece coordinate system directly determines the final machining accuracy. Therefore, obtaining the workpiece coordinate system for the workpiece being machined is crucial during robotic machining.

[0003] In the related art, traditional robot workpiece positioning methods primarily rely on manual instruction to obtain the coordinate values ​​of the features to be machined in the workpiece coordinate system. Based on this, and incorporating computer technology and other equipment, some new workpiece positioning methods have emerged in the related art. For example, patent CN 109848989 A discloses a method for automatic calibration and detection of the robot end-point using a ruby ​​probe. By using a fixed ruby ​​probe to perform touch-probe calibration on the workpiece surface contour, the workpiece's surface profile before and after machining is calculated and transmitted to the robot controller, enabling the robot end-point to calculate and display the workpiece surface profile. This method enables automatic calibration of the robot end-point and automatically completes surface profile detection before and after machining. Patent CN 110625600 A discloses a method for calibrating the workpiece coordinate system of the robot end-point. This method provides a method for manually teaching the robot to perform rough calibration of the workpiece end-point, and then fine calibration of the workpiece end-point using an algorithm. This method significantly improves the calibration accuracy of the robot end-point workpiece and reduces environmental and human error.

[0004] However, the workpiece calibration methods in related technologies all have defects. The manual teaching method is time-consuming and labor-intensive, inefficient, and the accuracy of the teaching points is also low. In actual situations, it is often necessary to obtain a large number of feature points, and manual teaching of these feature points is unrealistic. Although the method in the above patent document has high calibration accuracy, the computational workload is large and requires cyclic measurement iterations. At the same time, programming the host computer increases the difficulty of robot communication and host computer programming, and the implementation cost is high. Summary of the Invention

[0005] This application relates to a high-precision workpiece calibration method and workpiece calibration system, which can reduce the cost of the calibration process while ensuring calibration accuracy. The technical solution is as follows:

[0006] In one aspect, a high-precision workpiece calibration method is provided, which is applied to a robot controller and comprises:

[0007] Obtaining approximate coordinates corresponding to the target workpiece, where the approximate coordinates are used to indicate the placement position of the target workpiece;

[0008] Determine hole features, body features, and surface features corresponding to the target workpiece based on the approximate coordinates;

[0009] Determine a hole coordinate system corresponding to the target workpiece based on the hole characteristics;

[0010] Determine a body coordinate system corresponding to the target workpiece based on the body features;

[0011] Determine the surface coordinate system corresponding to the target workpiece based on the surface features;

[0012] According to the combined calibration strategy, a combined coordinate system corresponding to the target workpiece is generated based on the hole coordinate system, the body coordinate system and the surface coordinate system;

[0013] The target workpiece is measured and calibrated based on the combined coordinate system.

[0014] In an optional embodiment, according to a combined calibration strategy, a combined coordinate system corresponding to the target workpiece is generated based on a hole coordinate system, a body coordinate system, and a surface coordinate system, including:

[0015] Determine the characteristic dimensions corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system;

[0016] Combined with the characteristic size, determine the coordinate system priority corresponding to the hole coordinate system, body coordinate system and surface coordinate system;

[0017] Based on the coordinate system priorities, a combined coordinate system corresponding to the target workpiece is generated.

[0018] In an optional embodiment, the method further includes:

[0019] Determine the number of feature points to be measured corresponding to the hole coordinate system, the body coordinate system, and the surface coordinate system;

[0020] Based on the number of feature points to be measured and combined with the feature size, the coordinate system priority corresponding to the hole coordinate system, the body coordinate system and the surface coordinate system is determined.

[0021] In an optional embodiment, the number of hole-type features is at least two;

[0022] Determine the hole coordinate system corresponding to the target workpiece based on the hole features, including:

[0023] receiving at least three coordinate data corresponding to each hole feature, the coordinate data being used to indicate a point position on a sidewall of the hole feature;

[0024] Determining the coordinates of the center of a circle corresponding to the hole feature based on at least three coordinate data;

[0025] Determine the z-axis parameters corresponding to the target workpiece;

[0026] A hole coordinate system is established based on at least two circle center coordinates.

[0027] In an optional embodiment, determining a volume-type coordinate system corresponding to the target workpiece based on the volume-type feature includes:

[0028] Receive plane data corresponding to a volume-like feature, the plane data including at least three sets of coordinate data, each set of coordinate data including at least three coordinate data, the coordinate data being used to indicate a point position on a surface of the volume-like feature, and one set of coordinate data being used to indicate a surface of the volume-like feature;

[0029] determining plane equations corresponding to the three planes based on the plane data, and determining normal vectors corresponding to at least two of the planes;

[0030] Determine plane intersection points based on plane equations;

[0031] A volume-like coordinate system is established based on plane intersections and at least two normal vectors.

[0032] In an optional embodiment, determining a surface coordinate system corresponding to a target workpiece based on surface features includes:

[0033] Receive at least three coordinate data corresponding to the face feature, the coordinate data being used to indicate a point position on the surface of the face feature;

[0034] Determine the plane point normal equation corresponding to the surface feature based on the coordinate data;

[0035] Establish at least two projected coordinate systems corresponding to the surface features;

[0036] Determine at least two groups of reference point coordinates on the face feature, each group of reference point coordinates including at least two reference point coordinates, and determine the projection coordinates of the reference point coordinates on the projection plane;

[0037] Determine at least two plane lines based on at least two sets of reference point coordinates, and determine the coordinates of the intersection points corresponding to the plane lines;

[0038] A surface coordinate system is established based on the focal coordinates and the normal vector corresponding to the projected coordinate system.

[0039] In an optional embodiment, it is characterized in that the coordinate data is three-dimensional coordinate data.

[0040] In another aspect, a robot for performing a high-precision workpiece calibration method is provided;

[0041] The robot includes a robot body and a robot controller;

[0042] The robot body is communicatively connected with the robot controller;

[0043] The robot body has a tool holding portion, which is used to hold a measuring tool. When the measuring tool is in a working state, the measuring tool is in communication connection with the robot controller;

[0044] The robot controller is used to execute any of the above high-precision workpiece calibration methods.

[0045] The beneficial effects of the technical solution provided by this application include at least:

[0046] After determining the approximate placement of the target workpiece, different types of features are captured for the workpiece to generate multiple types of calibration sub-coordinate systems for each feature. Based on the calibration strategy, a combined coordinate system is ultimately generated. During the calibration process, the combined coordinate system is generated based on the multi-dimensional features, taking into account the feature types and the actual situation of the workpiece. This reduces the cost of the calibration process while ensuring accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0048] Figure 1 A schematic diagram of a robot for performing a high-precision workpiece calibration method provided by an exemplary embodiment of the present application is shown.

[0049] Figure 2 A schematic flow chart of a high-precision workpiece calibration method provided by an exemplary embodiment of the present application is shown.

[0050] Figure 3 A flow chart of another high-precision workpiece calibration method provided by an exemplary embodiment of the present application is shown.

[0051] Figure 4 A schematic diagram showing the structure of a target workpiece provided by an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0053] Figure 1 A schematic diagram of a robot for performing a high-precision workpiece calibration method provided by an exemplary embodiment of the present application is shown. Figure 1 The robot includes a robot body 110 and a robot controller 120. Figure 1 The robot body 110 has a tool holding portion 111, which is used to hold a measuring tool 112. When the measuring tool is in a working state, the measuring tool 112 is communicatively connected to the robot controller 120, and the robot body 110 is communicatively connected to the robot controller 120.

[0054] In this embodiment of the present application, the robot body 110 is a device that measures a target workpiece and generates various measurement data. The tool gripping portion 111 of the robot body 110 is capable of holding a measuring tool. Optionally, the measuring tool can be implemented as a wireless measuring device with a ruby ​​stylus, or an infrared measuring device.

[0055] When the robot controller 120 is communicatively connected to the robot 110 , the robot controller 120 can send data to the robot body 110 and control the movement of the tool gripping portion 111 of the robot body 110 .

[0056] Combine Figure 1 The workpiece calibration system shown, Figure 2 The following is a flow chart of a high-precision workpiece calibration method provided by an exemplary embodiment of the present application. Figure 2 , the method comprises:

[0057] Step 201: Obtain the approximate coordinates corresponding to the target workpiece.

[0058] This process is a pre-step for generating a multi-feature type coordinate system, that is, the process of obtaining the approximate coordinates corresponding to the target workpiece. Optionally, the robot can determine the approximate coordinates of the target workpiece by holding a machine vision device.

[0059] Step 202: determining hole features, body features, and surface features corresponding to the target workpiece based on the approximate coordinates.

[0060] In an embodiment of the present application, the target workpiece should include the above three types of features: hole features, which indicate that the target workpiece has a perforation or a cylinder; body features, which indicate that the target workpiece is formed as a solid with four or more surfaces; and surface features, which indicate that there is at least one plane on the target workpiece.

[0061] Step 203: Determine a hole coordinate system corresponding to the target workpiece based on the hole features.

[0062] Step 204 : Determine a volume-type coordinate system corresponding to the target workpiece based on the volume-type features.

[0063] Step 205: Determine a surface coordinate system corresponding to the target workpiece based on the surface features.

[0064] In steps 203 to 205, the robot controller generates a coordinate system using the received measurement data related to the corresponding features. Optionally, in the process of generating a type of coordinate system, the robot controller only uses data related to the type of features as input.

[0065] Step 206 : According to the combined calibration strategy, a combined coordinate system corresponding to the target workpiece is generated based on the hole coordinate system, the body coordinate system, and the surface coordinate system.

[0066] In an embodiment of the present application, the combined calibration strategy is used to indicate that during the subsequent calibration process, there are differences in the coordinate system characteristics of the hole coordinate system, the body coordinate system, and the surface coordinate system. Therefore, the robot controller will set a combined calibration strategy to generate the coordinate system type under the optimal circumstances.

[0067] Step 207 : perform measurement and calibration on the target workpiece based on the combined coordinate system.

[0068] In the embodiment of the present application, the subsequent measurement and calibration process of the target workpiece is performed with reference to the combined coordinate system.

[0069] In summary, the method provided in the embodiments of the present application, after determining the approximate placement position of the target workpiece, performs feature acquisition on the target workpiece, generating multiple types of calibration sub-coordinate systems for different features, and ultimately generating a combined coordinate system based on the calibration strategy. During the calibration process of the target workpiece, the combined coordinate system is generated after referencing the multi-dimensional features based on the feature types and the actual situation of the workpiece, and calibration is performed based on the combined coordinate system. This reduces the cost of the calibration process while ensuring calibration accuracy.

[0070] Figure 3 A flow chart showing another high-precision workpiece calibration method provided by an exemplary embodiment of the present application is shown. Figure 3 , the method comprising:

[0071] Step 301: Obtain the approximate coordinates corresponding to the target workpiece.

[0072] In the embodiments of the present application, before obtaining the approximate coordinates corresponding to the target workpiece, if the robot is capable of holding a visual device, it can perform a rough visual positioning of the target workpiece by photographing the work position. After this, the approximate coordinates are obtained, i.e., the placement position of the target workpiece is preliminarily determined. After determining the placement position of the target workpiece, the robot controller can then determine the approximate coordinates.

[0073] Step 302: determining hole features, body features, and surface features corresponding to the target workpiece based on the approximate coordinates.

[0074] This process corresponds to step 202, that is, the feature acquisition process for the target workpiece. In one example, the shape reference of the target workpiece Figure 4 , which includes hole features 401, body features 402 and surface features 403.

[0075] Next, this application will provide a detailed, step-by-step explanation of how to generate a hole coordinate system, a body coordinate system, and a surface coordinate system. Steps 303 to 306 describe the generation process for a hole coordinate system, steps 307 to 310 describe the generation process for a body coordinate system, and steps 311 to 316 describe the generation process for a surface coordinate system.

[0076] Step 303: Receive at least three coordinate data corresponding to each hole feature.

[0077] In this example, the coordinate data is used to indicate the location of a point on the sidewall of a hole feature.

[0078] In one example of the present application, the number of hole features is at least two. When determining the positions of at least two hole features, the robot controller can determine the coordinate system based on the Z axis corresponding to the target workpiece and the line connecting the centers of the two holes.

[0079] In an embodiment of the present application, corresponding to a hole feature, three point positions on its side wall will be measured. Optionally, the measuring tool is a wireless measuring device with a ruby ​​probe. At this time, points near the position corresponding to the point feature will be measured. In one example, the three points corresponding to a hole feature are (x1, y1, z1) (x2, y2, z2) and (x3, y3, z3). When the z-axis coordinates are straight, the coordinates of the three points can be determined to be (x1, y1) (x2, y2) and (x3, y3).

[0080] It should be noted that the coordinate data in the embodiments of the present application are all three-dimensional coordinate data, that is, in one example, the coordinates are (x, y, z). In some cases in the subsequent application, as described above, the coordinates will be simplified to (x, y).

[0081] Step 304: Determine the coordinates of the center of a circle corresponding to the hole feature based on at least three coordinate data.

[0082] In the embodiment of the present application, the three-point method described in the following formula 1 is used to determine the exact coordinates of the center of the circle (x0, y0):

[0083] Formula 1:

[0084] In the embodiment of the present application, if the number of hole features is at least two, then two center coordinates can be obtained.

[0085] Step 305: Determine the z-axis parameters corresponding to the target workpiece.

[0086] This process is the process of determining the z-axis parameters of the workpiece. Optionally, the z-axis parameters can be determined by considering the two hole features as being in the same plane.

[0087] Step 306: Establish a hole coordinate system based on at least two circle center coordinates.

[0088] Optionally, based on what has been described above, after determining the relevant parameters, a hole coordinate system can be established.

[0089] Step 307: Receive plane data corresponding to the volume type feature.

[0090] In an embodiment of the present application, the body feature corresponds to at least three planes. Therefore, the plane data corresponding to the body feature includes at least three sets of coordinate data, each set of coordinate data includes at least three coordinate data, and the coordinate data is used to indicate the point position on the surface of the body feature. One set of coordinate data is used to indicate a surface of the body feature.

[0091] Step 308 : determining plane equations corresponding to the three planes based on the plane data, and determining normal vectors corresponding to at least two planes.

[0092] In the embodiment of the present application, corresponding to the three coordinate data (x0, y0, z0) (x1, y1, z1) and (x2, y2, z2) in each plane, the robot controller can determine its plane point normal equation as shown in the following formula 2:

[0093] Formula 2: A(x-x0)+B(y-y0)+C(z-z0)=0

[0094] In this case, the point normal equation shown in Equation 3 and the plane general equation shown in Equation 4 can be determined:

[0095] Formula 3:

[0096] Formula 4:

[0097] Step 309: Determine the plane intersection point based on the plane equation.

[0098] In the embodiment of the present application, after obtaining Formula 3 and Formula 4, the coordinates of the intersection point O of the three planes can be determined as (XO, YO, ZO)

[0099] Step 310: Establish a volume-like coordinate system based on the plane intersection point and at least two normal vectors.

[0100] In the embodiment of the present application, after the intersection of the planes is determined, the body coordinate system can be determined by taking the normal vectors of the two planes as vectors and the intersection as the origin.

[0101] Step 311: Receive at least three coordinate data corresponding to the face feature.

[0102] For surface features, at least three coordinate data will be obtained in the embodiment of the present application, and the acquisition process is shown in the acquisition method of each surface for body features.

[0103] Step 312: Determine the plane point normal equation corresponding to the face feature based on the coordinate data.

[0104] In this case, the point normal equation can be directly determined as shown in the following formula 5:

[0105] Formula 5: A(x-x0)+B(y-y0)+C(z-z0)=0

[0106] Step 313: Establish at least two projection coordinate systems corresponding to the face features.

[0107] Step 314: Determine at least two sets of reference point coordinates on the face feature.

[0108] Step 315 : determining at least two plane lines based on at least two sets of reference point coordinates, and determining the coordinates of the intersection points corresponding to the plane lines.

[0109] Step 316: Establish a surface coordinate system based on the focus coordinates and the normal vector corresponding to the projected coordinate system.

[0110] In the embodiment of the present application, the plane normal vector can be determined by taking the plane corresponding to the face feature as the base plane. Two projection coordinate axes are established. For a point on a surface feature, its position on the two projection coordinate axes can be determined as a(x1, y1, z1) and b(x2, y2, z2). Since the calculation is performed on a plane projection, the coordinates can be simplified to a(x1, y1) and b(x2, y2). The vector shown in the following formula 6 is established through AB:

[0111] Formula 6:

[0112] Correspondingly, another vector can be established And the corresponding simplification is a plane straight line.

[0113] After solving the equations of the plane lines, the coordinates of the intersection point (x0, y0) can be determined, and based on the supplementary values, the origin of the coordinate system (x0, y0, z0) corresponding to the surface coordinate system can be determined, and a reference coordinate system can be established based on any vector.

[0114] Step 317: Determine the characteristic dimensions corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system.

[0115] Step 318: Determine the number of feature points to be measured corresponding to the hole coordinate system, the body coordinate system, and the surface coordinate system.

[0116] In the embodiment of the present application, the unit length of the characteristic dimension is different corresponding to different coordinate systems. In this case, the characteristic dimension with a larger unit length should be selected for calibration measurement.

[0117] Step 319 : Based on the number of feature points to be measured and in combination with the feature size, the coordinate system priorities corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system are determined.

[0118] Optionally, during the measurement process, the number of feature points that need to be additionally measured corresponding to different coordinate systems is different. At this time, the robot controller will determine the specific number of feature points and determine the priority corresponding to the three types of coordinate systems based on meeting the characteristic size principle.

[0119] Step 320 : Generate a combined coordinate system corresponding to the target workpiece based on the coordinate system priorities.

[0120] Step 321 : calibrate the target workpiece based on the combined coordinate system.

[0121] In summary, the method provided in the embodiments of the present application, after determining the approximate placement position of the target workpiece, performs feature acquisition on the target workpiece, generating multiple types of calibration sub-coordinate systems for different features, and ultimately generating a combined coordinate system based on the calibration strategy. During the calibration process of the target workpiece, the combined coordinate system is generated after referencing the multi-dimensional features based on the feature types and the actual situation of the workpiece, and calibration is performed based on the combined coordinate system. This reduces the cost of the calibration process while ensuring calibration accuracy.

[0122] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A high-precision workpiece calibration method, characterized in that: The method is applied to a robot controller, and the method includes: Acquire approximate coordinates corresponding to a target workpiece, wherein the approximate coordinates are used to indicate a placement position of the target workpiece; Determining hole features, body features, and surface features corresponding to the target workpiece based on the approximate coordinates; Determining a hole coordinate system corresponding to the target workpiece based on the hole features; Determining a volume coordinate system corresponding to the target workpiece based on the volume feature; Determining a surface coordinate system corresponding to the target workpiece based on the surface features; According to the combined calibration strategy, based on the hole coordinate system, the body coordinate system and the surface coordinate system, a combined coordinate system corresponding to the target workpiece is generated; Performing measurement and calibration on the target workpiece based on the combined coordinate system; Wherein, the number of the pore characteristics is at least two; The determining of a hole coordinate system corresponding to the target workpiece based on the hole feature includes: Receive at least three coordinate data corresponding to each hole feature, the coordinate data being used to indicate a point position on a sidewall of the hole feature; Determining the coordinates of the center of a circle corresponding to the hole feature based on the at least three coordinate data; Determining z-axis parameters corresponding to the target workpiece; Establishing the hole coordinate system based on at least two of the circle center coordinates; The determining of a volume coordinate system corresponding to the target workpiece based on the volume feature includes: Receive plane data corresponding to the volume-like feature, the plane data including at least three sets of coordinate data, each set of coordinate data including at least three coordinate data, the coordinate data being used to indicate a point position on the surface of the volume-like feature, and one set of coordinate data being used to indicate a surface of the volume-like feature; determining plane equations corresponding to the three planes based on the plane data, and determining normal vectors corresponding to at least two planes; determining a plane intersection point based on the plane equation; Establishing the body-like coordinate system based on the plane intersection and at least two normal vectors; The determining of a surface coordinate system corresponding to the target workpiece based on the surface features includes: receiving at least three coordinate data corresponding to the face feature, wherein the coordinate data is used to indicate a point position on the surface of the face feature; Determining a plane point normal equation corresponding to the face feature based on the coordinate data; Establishing at least two projection coordinate systems corresponding to the face features; Determine at least two groups of reference point coordinates on the face feature, each group of reference point coordinates including at least two reference point coordinates, and determine projection coordinates of the reference point coordinates on a projection plane; Determine at least two plane lines based on at least two sets of reference point coordinates, and determine the coordinates of the intersection points corresponding to the plane lines; The surface coordinate system is established based on the intersection coordinates and the normal vector corresponding to the projected coordinate system.

2. The method according to claim 1, characterized in that The generating of a combined coordinate system corresponding to the target workpiece based on the hole coordinate system, the body coordinate system, and the surface coordinate system according to the combined calibration strategy includes: Determining characteristic dimensions corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system; Determining the coordinate system priorities corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system in combination with the characteristic size; Based on the coordinate system priorities, a combined coordinate system corresponding to the target workpiece is generated.

3. The method according to claim 2, characterized in that The method further comprises: Determine the number of feature points to be measured corresponding to the hole coordinate system, the body coordinate system, and the surface coordinate system; Based on the number of feature points to be measured and in combination with the feature size, the coordinate system priorities corresponding to the hole-type coordinate system, the body-type coordinate system, and the surface-type coordinate system are determined.

4. The method according to claim 1, wherein The coordinate data is three-dimensional coordinate data.

5. A robot for performing a high-precision workpiece calibration method, characterized in that: The robot includes a robot body and a robot controller; The robot body is communicatively connected to the robot controller; The robot body has a tool holding portion, the tool holding portion is used to hold a measuring tool, and when the measuring tool is in a working state, the measuring tool is communicatively connected with the robot controller; The robot controller is used to execute the high-precision workpiece calibration method according to any one of claims 1 to 4.

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