A real-time measurement and adjustment method for spatial pose positioning of a support type workpiece

Abstract

The application provides a support workpiece space position positioning real-time measurement and adjustment method, which comprises the following steps: measured element simplification feature conversion, space position coordinate conversion, positioning deviation value calculation, and space position real-time measurement and adjustment, so as to realize support space position positioning. The method provided by the application provides a new technical approach for enterprises to solve the position positioning of such workpieces, the positioning process does not need to manufacture special measurement tools and skips processes such as line marking and table marking, optimizes the measurement process, and saves the manufacturing cost.

Description

Technical Field

[0001] This invention belongs to the field of precision geometric measurement technology, and specifically relates to a method for real-time measurement and adjustment of the spatial pose positioning of support-type workpieces. Background Technology

[0002] In the field of geometric precision measurement technology, laser trackers are the preferred choice for measuring and assembling large-size spatial components. They have powerful capabilities for precise spatial coordinate measurement. However, there are two difficult technical problems to solve in practical applications: First, the position of the measured element of the component is special, and other elements may block the laser tracker's reflective target ball from receiving the measurement laser beam, thus making measurement impossible. Second, the real-time pose of the component to be adjusted cannot be monitored during the spatial pose adjustment process, requiring multiple cycles of "measurement-adjustment" to meet the technical requirements.

[0003] In this regard, for example, refer to Figure 1 The diagram shows a schematic representation of an example three-dimensional frame structure. Figure 2 The figures shown are the top and front views of the assembly drawing of the frame. The frame is a cuboid structure (total length 4 meters). Reference A is the midpoint between the inner surfaces of the two lugs on the left end of the frame. The support at the groove on the right side of the figure is the workpiece whose spatial pose needs to be measured and positioned. Its spatial pose technical specifications are: the vertical dimension relative to the lugs of the frame needs to reach (505±0.15) mm, and the symmetry of the inner surface of the support relative to the left lugs needs to reach 0.2 mm. Among these, the horizontal distance between the support to be positioned and the two lugs on the left end of the frame exceeds 3 meters, which falls within the scope of precision measurement of large-scale spatial geometric quantities.

[0004] To obtain the required measurement results mentioned above, such as Figure 3As shown, laser trackers are generally used to measure the spatial pose of such workpieces. However, the laser beam is obstructed by the measured part of the frame, so the laser tracker's reflector cannot directly measure the data of the inner cylindrical surface of the support. Therefore, a T-Probe module must be used. Without an extended measuring rod, the maximum permissible error of the T-Probe module is 0.035mm. If an extended measuring rod is used, considering environmental and personnel factors, the maximum permissible error will exceed 0.08mm. Based on measurement principles, the ratio of the inherent maximum permissible error of the selected measuring instrument to the corresponding value of the product dimensional tolerance limit is 1 / 3 to 1 / 10, meaning the minimum dimensional tolerance of the measured workpiece is 0.24mm. It is evident that the T-Probe module of the laser tracker is insufficient in terms of accuracy for direct measurement of the support posture. Since the measured element of the support is a cylindrical surface, the measurement process requires collecting data from the inner surfaces of the two supports, and then measuring the cylindrical section using these two inner surfaces as projection planes to evaluate the theoretical posture deviation. In this case, the posture adjustment process relies on scribing and other measuring tools. This posture adjustment process involves measuring data once and then adjusting based on that data. The adjustment amount cannot be monitored in real time, and the adjusted dimensions may influence each other; that is, while the dimensions may meet the requirements, the symmetry may not. This results in a cyclical posture adjustment process with extremely low efficiency. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention proposes a real-time spatial pose positioning measurement and adjustment method based on "simplified feature transformation of the measured element" for support-type workpieces where the measured elements are obstructed. This method uses a laser tracker reflector ball for measurement, with a maximum permissible error of ±(0.015+6L / 1000) mm, where L is the measurement distance in meters. Before positioning the support, the dimensions of the support portion need to be measured using a digital height gauge, with a maximum permissible error of ±(3+3L / 1000) μm, where L is the measurement distance in millimeters. This enables real-time spatial pose positioning measurement and adjustment for this type of support workpiece.

[0006] Specifically, the present invention provides a method for real-time measurement and adjustment of the spatial pose positioning of a support-type workpiece, the method comprising the following steps:

[0007] (1) Simplified feature conversion of the measured element: Determine the near-obstructed end face of the support to be measured, and measure the vertical distance (a, b) from the point to be measured on the support to its near-obstructed end face and the horizontal distance (c) between the inner surfaces of the support. Then, convert the point to be measured on the support into a measurement point (A, B) on the near-obstructed end face, and convert the inner surface of the measured element of the support into any measurement point (C) on the inner surface.

[0008] (2) Spatial pose coordinate transformation: Determine the fixed vertical distance (h) from the measuring instrument reflection point to the measuring point (A, B, C), and then calculate the spatial position relationship between the transformed measuring point (A, B, C) and the reference point.

[0009] (3) Calculation of positioning deviation: Data is collected on the object to be connected and the reference point. Based on this data, the object coordinate system (X, Y, Z) and the coordinate system zero point are established. The measurement point (A, B, C) information is measured with a measuring instrument. The deviation value of the measurement point (A, B, C) relative to the theoretical position is obtained by comparing the position relationship calculated in step (2).

[0010] (4) Real-time measurement and adjustment of spatial pose: Adjust the spatial pose of the support according to the deviation value obtained in step (3), and at the same time repeat the measurement of the deviation value in step (3) until the deviation values ​​of the measurement points (A, B, C) all enter the tolerance zone, then the spatial pose positioning of the support is completed.

[0011] The point to be measured on the support is the geometric center of the cylindrical hole inside the support.

[0012] Furthermore, in step (2), the spatial relationship between the measurement points (A, B) and the reference point is as follows: the theoretical vertical distance between the reference point and the reflection point of the measurement point (A, B) near the obstructed end face is Lha or Lhb, where L is the theoretical vertical distance between the support to be measured point and the reference point.

[0013] Furthermore, in step (2), the spatial relationship between the measurement point (C) and the reference point is as follows: the theoretical distance between the coordinate system zero point and the reflection point of the measurement point (C) on any inner side of the support is c / 2-h.

[0014] Furthermore, in step (4), the tolerance zone of the reflection point of the near-obstructed end face measurement point (A, B) is generally ±0.15mm; the tolerance zone of the reflection point of any inner side measurement point (C) of the support is generally ±0.1mm, and the symmetry is 0.2mm.

[0015] More specifically, taking the positioning of a support component in a large-sized spatial frame (large workpiece) as an example, this invention also provides a method for real-time measurement and adjustment of the spatial pose positioning of support-type workpieces. The specific steps of the method are as follows:

[0016] (1) Simplified feature conversion of the measured element: Measure the vertical distance (a, b) from the geometric center of the two inner cylindrical holes of the support to their near-obstructed end face, thereby determining the measurement points (A, B) on the near-obstructed end face of the support where the geometric centers of the two cylinders are aligned; measure the horizontal distance (c) between the two inner surfaces of the support; based on this, the cylindrical surface of the measured element of the support is converted into the measurement point (A, B) on the near-obstructed end face, and the inner surface of the measured element of the support is converted into any measurement point (C) on the inner surface.

[0017] (2) Spatial pose coordinate transformation: Solve the spatial positional relationship between the transformed measurement elements and the frame reference point; determine the vertical distance between the center of the laser tracker reflector ball and its base surface as h (generally 25mm, with a maximum allowable error of ±0.005mm), and calculate the theoretical vertical distances between the frame reference point and the measurement points (A, B) near the obstruction end face of the support as Lha or Lhb, where L is the theoretical vertical distance between the point to be measured on the support and the reference point, and the theoretical front-to-back distance between the inner mid-plane of the reference object and the measurement point (C) of any inner side of the support as c / 2-h;

[0018] (3) Calculation of positioning deviation: The laser tracker is used to measure the information of the measured elements of the frame, and the measurement results are calculated. The laser tracker is placed on the end of the frame close to the reference object, and a reflector ball is used to collect data on the upper surface of the frame and the inner cylindrical surfaces of the two reference objects. Based on this data, a coordinate system for the frame is established. The direction perpendicular to the upper surface of the frame and upward is the positive Z direction, the direction parallel to the line connecting the centers of the two reference objects is the X direction, the direction along the length of the frame is the Y direction, and the intersection of the line connecting the symmetrical mid-surfaces of the two reference objects and their centers is the zero point of the coordinate system. The reflector ball is then placed on the frame. Place the sphere at measurement points (A, B), and measure the vertical distance z between the center of the reflecting sphere and the reference point in the Z coordinate using a laser tracker. Calculate the difference between z and Lha or Lhb, which is the vertical deviation of the measurement point (A, B) relative to the theoretical position. Attach the reflecting sphere and the measuring base to any measurement point (C) on the inner side of the support, and measure the distance x from the center of the reflecting sphere to the midpoint of the reference object in the X coordinate using a laser tracker. Calculate the difference between x and c / 2-h, which is the symmetry deviation of the measurement point (C) relative to the theoretical position.

[0019] (4) Real-time measurement and adjustment of spatial pose: Adjust the spatial pose of the support according to the obtained deviation value. First, measure the points (A, B) in the Z coordinate system so that the vertical deviation of z relative to the theoretical position enters the tolerance zone of ±0.15mm. Then adjust the measurement point (C) in the X coordinate system so that the symmetry deviation of x relative to the theoretical position enters the tolerance zone of ±0.1mm and the symmetry is 0.2mm. After completing one cycle of adjusting the pose of the measurement points (A, B, C), verify whether the position of the measurement points (A, B) in the Z coordinate system has entered the tolerance zone. Then re-verify the measurement point (C) in the X coordinate system until all measurement points (A, B, C) have completely entered the tolerance zone. Then the spatial pose positioning of the support is completed.

[0020] The advantages of the real-time measurement and adjustment method for spatial pose positioning of support-type workpieces provided by this invention are as follows:

[0021] 1. Based on the method of "simplified feature transformation of the measured element", the complex multi-element measured element is transformed into a simple three-point element, realizing real-time measurement and real-time adjustment of spatial pose positioning. This solves the problem of high-precision positioning of measured elements in special positions of large workpieces such as supports, and greatly improves positioning efficiency.

[0022] 2. Through the combined application of measuring instruments and dimensional chain analysis, the measurement accuracy of this project is better than 0.05mm, which expands the measurement range of mainstream laser trackers and provides a brand-new application method for combined measuring instruments.

[0023] 3. It provides a brand-new technical approach for enterprises to solve the positioning of such workpieces. The positioning process does not require the manufacture of special measuring fixtures and skips processes such as scribing and dial indicator printing, thus optimizing the measurement process and saving manufacturing costs. Attached Figure Description

[0024] Figure 1 This is a three-dimensional schematic diagram of a large-sized frame as an example of a method for real-time measurement and adjustment of spatial pose positioning of a support-type workpiece according to the present invention.

[0025] Figure 2 for Figure 1 The top and front views of an exemplary frame are shown, with the design dimensions required for machining and installing the supports marked.

[0026] Figure 3 for Figure 1 A schematic diagram of the measurement method of an existing laser tracker for an exemplary frame.

[0027] Figure 4 for Figure 1 A schematic diagram illustrating the measurement point transition during the measurement and adjustment process of the right-side support in the exemplary frame.

[0028] Among them, 1 is the frame; 2 is the lug; 3 is the support; and 4 is the reflector ball. Detailed Implementation

[0029] The "Real-time Measurement and Adjustment Method for Spatial Pose Positioning of Support-type Workpieces" of the present invention will be further described with reference to the accompanying drawings.

[0030] In this example, with Figure 1 The rectangular, large-scale spatial frame 1 shown is used as an example to illustrate the specific steps of the real-time measurement and adjustment method for spatial pose positioning of a support-type workpiece provided by the present invention. Among them, Figure 1 The support 3 in the groove on the right side is the workpiece whose position is to be measured and positioned. Its spatial position technical indicators are: the vertical dimension relative to the frame support ear 2 needs to reach (505±0.15)mm, and the symmetry of the inner side of the support 3 with respect to the left end support ear 2 needs to reach 0.2mm.

[0031] It should be noted that the specific dimensions of the workpiece and components mentioned in this article (e.g., those mentioned above / ) are not specified. Figure 2 The 505mm, etc. shown are exemplary illustrations of the specific processing requirements of this particular workpiece, intended to more intuitively and clearly explain the real-time measurement and adjustment method provided by the present invention. These specific dimensions should not be construed as limiting the scope and spirit of the present invention.

[0032] Therefore, this invention provides a method for real-time measurement and adjustment of the spatial pose positioning of support-type workpieces, comprising:

[0033] 1. Simplified feature conversion of the measured element: Use a digital height gauge to measure the vertical distance from the two inner cylindrical holes of support 3 to their upper end faces, such as... Figure 4 The theoretical value shown is 120mm. The measurement point is located on the upper surface of support 3 and is aligned with the geometric centers of the two cylinders, i.e. Figure 4 Points A and B in the diagram are measured and recorded as [a, b] respectively; the horizontal distance between the two inner surfaces of support 3 is measured, as shown below. Figure 4 The theoretical value shown is 60mm, and the measurement result is recorded as [c]. The two inner surfaces are precision-machined surfaces, so the horizontal distance between any two points on their surfaces is almost the same, and the measurement error is no greater than 0.01mm. Based on this, the cylindrical surface of the measured element of support 3 is converted into measurement points A and B on the upper end face, and the inner surface of the measured element of support 3 is converted into any measurement point C on the inner surface. That is, the measured element is converted from four elements, two planes and two circles, into three measurement point elements, A, B and C.

[0034] 2. Spatial pose coordinate transformation: Solve the spatial positional relationship between the transformed measurement elements and the left end lug 2 of the frame 1. The laser tracker reflector sphere 4 and the measuring base are high-precision standard parts. The vertical distance between the center of the reflector sphere 4 and the base surface of the measuring base is 25mm, with a maximum permissible error of ±0.005mm. For example... Figure 2 As shown, the theoretical vertical distances between the left end lug 2 of the frame 1 and the measuring point of the reflector 4 on the upper surface of the support 3 can be calculated as [505-25-a, 505-25-b] mm, and the front-to-back distance between the inner mid-plane of the lug 2 and the measuring point of the reflector 4 on any inner side of the support 3 is [c / 2-25] mm.

[0035] 3. Positioning Deviation Calculation: The measurement results are calculated by measuring the measured elements of frame 1 using a laser tracker. For example... Figure 3 As shown, the laser tracker is placed on the frame 1 near the two lugs 2. The reflector 4 is used to collect data on the upper surface of the frame 1 and the inner cylindrical surfaces of the two lugs 2. Based on this data, the coordinate system of the frame 1 is established. The positive Z direction is perpendicular to the upper surface of the frame 1 and upward. The X direction is parallel to the line connecting the centers of the two lugs 2. The Y direction is along the length of the frame 1. The intersection of the line connecting the symmetrical mid-surface of the two lugs 2 and its center is the zero point of the coordinate system. Place the reflector 4 at measurement points A and B on the upper surface of the support 3 to be measured. Open the monitoring window of the laser tracker. The displayed Z coordinate [z] is the vertical distance between the center of the reflector 4 and the left end lug 2. Calculate the difference between [z] and [505-25-a], which is the vertical deviation of point A relative to the theoretical position. Similarly, the vertical deviation of point B can be obtained. Attach the reflector 4 and the measuring base to any point on the inner side of the support 3. The X coordinate [x] displayed in the monitoring window of the laser tracker is the distance from the center of the reflector 4 to the midpoint of the lug 2. Calculate the difference between [x] and [c / 2-25], which is the symmetry deviation of point C relative to the theoretical position.

[0036] 4. Real-time Spatial Pose Measurement and Adjustment: Adjust the spatial pose of support 3 according to the values ​​displayed in the monitoring window. First, adjust points A and B by gently tapping vertically to change the Z-coordinate [z] so that its vertical deviation from the theoretical position is within the tolerance zone of ±0.15mm. Then, adjust point C by gently tapping horizontally to change the X-coordinate [x] so that its symmetry deviation from the theoretical position is within the tolerance zone of ±0.1mm (symmetry 0.2mm). Repeat this operation to complete one cycle of adjusting the poses of points A, B, and C. Then verify whether the positions of points A and B are within the tolerance zone, and then recheck point C. Continue until the monitoring window shows that the values ​​of points A, B, and C are all completely within the tolerance zone. At this point, the spatial pose positioning of support 3 is complete.

[0037] In the existing technology, the general solution for solving the spatial pose positioning of such workpieces is as follows: use a laser tracker T-Probe module and an extended measuring rod to measure the occlusion elements, adjust their size and position according to the deviation of the measurement data, and use auxiliary means such as scribing and dial indicator during the adjustment process. After the adjustment is completed, the measurement is carried out again. After multiple cycles of "measurement-adjustment", the spatial pose positioning work is finally completed.

[0038] However, it is obvious that when using the T-Probe module of the laser tracker and the extended measuring rod to measure the obstructed elements, the measurement positioning is difficult to achieve when the positioning accuracy of the measured element is high due to the superposition of measurement errors caused by the T-Probe module itself, the extended measuring rod, the measurement personnel and environmental factors.

[0039] However, the method provided by this invention has considerable novelty and uniqueness in the real-time measurement and adjustment method of spatial pose positioning based on "simplified feature conversion of measured elements" for the occlusion of the measured elements of support-type workpieces: (1) "Simplified feature conversion of measured elements" brings out the hidden points, uses a digital display height meter to measure the basic size data of the workpiece to be positioned, and then uses a laser tracker reflector ball to achieve high-precision spatial pose positioning, eliminating the need for special tooling manufacturing and greatly saving measurement costs; (2) It breaks away from the fixed thinking that spatial pose positioning measurement of occluded parts requires customized special measuring tooling, and provides a new application case of instrument combination measurement with a new measurement method of precise dimension chain transmission and analysis; (3) By converting the complex multi-element measured elements into three simple point elements, the real-time measurement of the spatial pose information of the measured elements can be realized, providing a way for real-time adjustment of the workpiece pose and greatly improving the positioning efficiency.

[0040] Under the same level of difficulty, there is currently no other more economical technology that can achieve real-time measurement and adjustment of the spatial pose of this type of workpiece.

[0041] It should be understood that the directional indicators such as "left," "right," "up," "down," and "inside / outside" mentioned herein are based on the orientation of the device as shown in the example diagram. It should also be understood that the positions of "up," "down," "left," "right," "inside," and "outside" in the present invention are interchangeable and do not constitute a substantial limitation on the present invention.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for real-time measurement and adjustment of the spatial pose positioning of a support-type workpiece, characterized in that, The spatial pose technical specifications are: the vertical dimensions of the support relative to the lug, and the symmetry of the inner surface of the support relative to the left lug; the reference point is the geometric center of the cylindrical hole of the two lugs; the method includes the following steps: (1) Simplified feature conversion of the measured element: Measure the vertical distances a and b from the geometric center of the two inner cylindrical holes of the support to their near-obstructed end faces, and thus determine the measurement points A and B on the near-obstructed end faces of the support that are aligned with the geometric centers of the two cylinders; measure the horizontal distance c between the two inner surfaces of the support; based on this, the cylindrical surface of the measured element of the support is converted into measurement points A and B on the near-obstructed end faces, and the inner surface of the measured element of the support is converted into any measurement point C on the inner surface. (2) Spatial pose coordinate transformation: Solve the spatial positional relationship between the transformed measurement elements and the reference point of the large workpiece; determine the vertical distance h between the center of the laser tracker's reflector ball and its base surface; calculate the theoretical vertical distance Lha or Lhb between the reference point of the large workpiece and the measurement points A and B of the support near the obstruction end face, where L is the theoretical vertical distance between the support's measurement point and the reference point; the theoretical front-to-back distance between the inner mid-plane of the two ears of the reference object and the measurement point C of the support's arbitrary inner side surface is (c / 2)-h. (3) Calculation of positioning deviation: The laser tracker measures the measured element information of the large workpiece and calculates the measurement result; the laser tracker is placed near the reference end of the large workpiece, and the reflector ball is used to collect data on the upper surface of the large workpiece and the inner cylindrical surface of the two ears. Based on this data, the coordinate system of the large workpiece is established. The direction perpendicular to the upper surface of the large workpiece is upward, the direction parallel to the line connecting the centers of the two ears is the X direction, the direction along the length of the large workpiece is the Y direction, and the intersection of the line connecting the symmetrical mid-surface of the two ears and its center is the zero point of the coordinate system; the reflector ball is placed at measurement points A and B respectively, and the vertical distance z between the center of the reflector ball and the reference point in the Z coordinate is measured by the laser tracker. The difference between z and Lha or Lhb is the vertical deviation value of measurement points A and B relative to the theoretical position; the reflector ball and the measuring seat are attached to any measurement point C on the inner side of the support, and the distance x from the center of the reflector ball to the mid-section of the ear in the X coordinate is measured by the laser tracker. The difference between x and (c / 2)-h is the symmetry deviation value of measurement point C relative to the theoretical position. (4) Real-time measurement and adjustment of spatial pose: Adjust the spatial pose of the support according to the obtained deviation value. First, adjust the measurement points A and B in the Z coordinate system so that the vertical deviation value of z relative to the theoretical position enters the tolerance zone of ±0.15mm. Then adjust the measurement point C in the X coordinate so that the symmetry deviation value of x relative to the theoretical position enters the tolerance zone of ±0.1mm and the symmetry is 0.2mm. After completing one cycle of adjusting the pose of measurement points A, B, and C, verify whether the positions of measurement points A and B in the Z coordinate system have entered the tolerance zone. Then re-verify the measurement point C in the X coordinate until all measurement points A, B, and C have completely entered the tolerance zone. Then the spatial pose positioning of the support is completed.

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