Laser tracker temperature compensation calculation method and device for tool measurement

Abstract

The invention discloses a laser tracker temperature compensation calculation method and device for tool measurement, and the method comprises the steps: considering the difference of thermal expansion coefficients between a temperature compensation plate and a tool main body frame in a large assembly tool; and the anchor point position of the temperature compensation plate relative to the tool main body frame and the anchor point position of the tool main body frame relative to the foundation are considered, so that the temperature compensation calculation method of the calibration point on the temperature compensation plate of the assembly tool is obtained. An analogue simulation result shows that the calculation method provided by the invention can effectively eliminate temperature deformation.

Description

Technical Field

[0001] The present invention belongs to the technical field of digital measurement, and in particular relates to a temperature compensation calculation method and device of a laser tracker used for tooling measurement. Background Art

[0002] In aircraft manufacturing, assembly quality requirements are becoming increasingly stringent to ensure good interchangeability and assembly coordination of aircraft components, as well as higher overall performance. Assembly accuracy is often required to be sub-millimeter or even higher. However, thermal deformation is inevitable due to ambient temperature fluctuations, which directly impacts the assessment of product assembly status. For small and medium-sized components, thermal deformation is minimal, and the operating temperature is relatively easy to control, making the impact of temperature on assembly less significant. However, for large aircraft, the larger dimensions of parts and components lead to greater thermal deformation, and the temperature in the large spaces is difficult to control, making the impact of temperature significant. For example, a 20-meter-long aluminum alloy sheet will thermally deform approximately 2.4 mm with a 5°C temperature change. When using a laser tracker to measure calibration points on large tooling, directly using these measurements for assembly status inspection and assessment clearly fails to meet assembly requirements. Therefore, compensation for temperature-induced thermal deformation is often required before assessment.

[0003] While current laser measurement equipment possesses certain temperature compensation capabilities, its compensation method is primarily limited to a proportional factor correction based on the thermal expansion coefficient of a single material. This traditional compensation method fails to fully account for the differences in thermal expansion between different materials and the influence of anchor point location. For large assembly fixtures with temperature compensation plates, the anchor position of the fixture relative to the foundation, the anchor position of the temperature compensation plate relative to the fixture, and the different thermal expansion coefficients between the fixture frame and the temperature compensation plate all significantly impact the temperature compensation calculation. Therefore, using the current method of calculating a proportional factor based on the thermal expansion coefficient for temperature compensation calculations will clearly result in inaccurate temperature compensation for large-scale measured objects, which can significantly amplify measurement deviations. Therefore, when measuring large assembly fixtures, it is necessary to consider the effects of anchor point location and the different thermal expansion coefficients between different materials. Summary of the Invention

[0004] The present invention aims to address the problem of large measurement errors in large assembly tooling measurements, caused by the current laser tracker method for calculating the proportionality factor based on the thermal expansion coefficient, which fails to fully account for relevant influencing factors. The present invention provides a laser tracker temperature compensation calculation method and device for tooling measurement. This method accounts for the different thermal expansion coefficients between the anchor point location, the tooling main frame, and the temperature compensation plate.

[0005] A first aspect of the present invention provides a temperature compensation calculation method for a laser tracker used for tool measurement. The measured assembly tool includes: a main frame and a temperature compensation plate; the method includes:

[0006] Step 1: Use a laser tracker to measure the coordinates of the calibration points and anchor points on the assembly tooling, and record the ambient temperature of this measurement; the anchor points include: the anchor point of the main frame relative to the foundation and the anchor point of the temperature compensation plate relative to the main frame; the calibration points are set on the temperature compensation plate;

[0007] Step 2: When the ambient temperature changes, the laser tracker is used to measure the coordinates of the calibration point and the anchor point again, and the ambient temperature of this measurement is recorded;

[0008] Step 3: Correct the coordinates in step 2 using the following temperature compensation formula to eliminate thermal deformation caused by ambient temperature changes;

[0009] u′=β(u+γ);

[0010] Where u is the coordinate of the calibration point after temperature change, and the calibration point is any calibration point on the temperature compensation board; u′ is the coordinate value of u after correction; is the proportional factor; γ=α2ΔTu F2 +α1ΔT(u F1 -u F2 ) is the compensation coefficient; α1 and α2 are the thermal expansion coefficients of the main frame and the temperature compensation plate respectively; u F1 、u F2 are the coordinates of the main frame anchor point and the temperature compensation plate anchor point in step 1; ΔT is the temperature difference between the two measurements.

[0011] Optionally, the temperature compensation calculation method for the laser tracker used for tooling measurement also includes:

[0012] Step 4: Subtract the coordinates of the calibration point in step 1 from the coordinates corrected in step 3 to determine whether the measured data is within the allowable error range.

[0013] Optionally, the calibration points are arranged along the length direction of the temperature compensation plate.

[0014] Optionally, the length of the temperature compensation plate is not less than 10 meters.

[0015] A second aspect of the present invention also provides a temperature compensation calculation device for a laser tracker used for tooling measurement. The measured assembly tooling includes: a main frame and a temperature compensation plate; the device includes:

[0016] The first measurement module is used to measure the coordinates of the calibration points and anchor points on the assembly tool using a laser tracker, and record the ambient temperature of the measurement; the anchor points include: the anchor point of the main frame relative to the foundation and the anchor point of the temperature compensation plate relative to the main frame; the calibration points are set on the temperature compensation plate;

[0017] The second measurement module is used to measure the coordinates of the calibration point and the anchor point again using the laser tracker when the ambient temperature changes, and record the ambient temperature of this measurement;

[0018] A correction module, used to correct the coordinates in the second measurement module using the following temperature compensation formula, thereby eliminating thermal deformation caused by changes in ambient temperature;

[0019] u′=β(u+γ);

[0020] Where u is the coordinate of the calibration point after temperature change, and the calibration point is any calibration point on the temperature compensation board; u′ is the coordinate value of u after correction; is the proportional factor; γ=α2ΔTu F2 +α1ΔT(u F1 -u F2 ) is the compensation coefficient; α1 and α2 are the thermal expansion coefficients of the main frame and the temperature compensation plate respectively; u F1 、u F2 are the coordinates of the main frame anchor point and the temperature compensation plate anchor point in step 1; ΔT is the temperature difference between the two measurements.

[0021] Optionally, the device further includes:

[0022] The judgment module is used to calculate the difference between the coordinates of the calibration point after correction and the coordinates before deformation, and to judge whether the measurement data is within the allowable error range.

[0023] A third aspect of the present invention provides a computer-readable storage medium, comprising: a memory and a processor;

[0024] The memory is configured to store executable instructions;

[0025] The processor is configured to implement the method as described in any one of the first aspects when executing the executable instructions stored in the memory.

[0026] A fourth aspect of the present invention provides a computer program product, comprising instructions, which, when executed by a computer, implement the method as described in any one of the first aspects.

[0027] The beneficial effects of the present invention: To address the shortcomings of laser tracker temperature proportional compensation calculation methods in large-scale assembly tooling measurements, the present invention proposes a laser tracker temperature compensation calculation method and device for tooling measurement. This method fully considers the difference in thermal expansion coefficients between the temperature compensation plate and the tooling main frame in large-scale assembly tooling, the anchor point position of the temperature compensation plate relative to the tooling main frame, and the anchor point position of the tooling main frame relative to the foundation, resulting in an effective and accurate laser tracker temperature compensation calculation method. The calculation method proposed by the present invention can more accurately eliminate the impact of temperature changes on measurement data and is better suited for measuring large-scale assembly tooling with temperature compensation plates, thereby more accurately reflecting assembly quality and improving the assembly production efficiency of large aircraft components. Furthermore, compared with existing laser tracker measurement processes, the present invention only requires the addition of anchor point position measurement and the provision of thermal expansion coefficients of the temperature compensation plate and tooling main frame during the measurement process, with virtually no increase in operational complexity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a thermal deformation structure for deriving the calculation method provided by the present invention;

[0029] Figure 2 A schematic diagram of a large-scale frame assembly tool provided in an embodiment of the present invention;

[0030] Figure 3 1 is the coordinate comparison result of the calibration point before deformation, after deformation and correction in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0032] The features and illustrative embodiments of various aspects of the present invention will be described in detail below. In the detailed description below, many specific details are proposed in order to provide a comprehensive understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention. The present invention is in no way limited to any specific arrangement and method proposed below, but rather encompasses any improvements, replacements, and modifications to structures, methods, and devices without departing from the spirit of the present invention. In the accompanying drawings and the following description, well-known structures and techniques are not shown to avoid unnecessary ambiguity in the present invention.

[0033] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "up," "down," "left," "right," "vertical," "horizontal," "inside," and "outside" are based on the directions or positional relationships described in the accompanying drawings and are intended only to facilitate and simplify the description of the present invention and should not be construed as limiting the present invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is intended to distinguish between objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0034] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly, and may refer to direct connection or indirect connection through an intermediary. Those skilled in the art will understand the specific meanings of these terms in the present invention.

[0035] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other, and the embodiments can refer to and quote each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0036] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0037] The present invention provides a laser tracker temperature compensation calculation method and device for tooling measurement. The tooling structure to be measured includes a main frame, a temperature compensation plate, and several calibration points. The main frame is sufficiently large in at least one dimension to not neglect the effects of temperature changes on its deformation. The temperature compensation calculation fully considers the effects of differences in thermal expansion coefficients between the temperature compensation plate and the tooling in large assembly tooling, as well as the anchor position of the temperature compensation plate relative to the tooling main frame and the anchor position of the tooling main frame relative to the foundation.

[0038] The main frame and the foundation of the present invention have an anchor point, the temperature compensation plate is also at the anchor point relative to the main structure, and the calibration point is attached to the temperature compensation plate.

[0039] The present invention provides a temperature compensation calculation method for a laser tracker for tooling measurement, the main steps of which include:

[0040] Step 1: Use a laser tracker to measure the coordinates of the calibration points and anchor points on the large equipment tooling, and record the ambient temperature of this measurement;

[0041] Step 2: When the ambient temperature changes, the laser tracker is used to measure the coordinates of the calibration point and the anchor point again, and the ambient temperature is recorded at the same time;

[0042] Step 3: Correct the coordinates in step 2 using the following temperature compensation formula to eliminate thermal deformation caused by ambient temperature changes;

[0043] u′=β(u+γ);

[0044] Where u is the coordinate of the calibration point after temperature change, and the calibration point is any calibration point on the temperature compensation board; u′ is the coordinate value of u after correction; is the proportional factor; γ=α2ΔTu F2 +α1ΔT(u F1 -u F2 ) is the compensation coefficient; α1 and α2 are the thermal expansion coefficients of the main frame and the temperature compensation plate respectively; u F1 、u F2 are the coordinates of the main frame anchor point and the temperature compensation plate anchor point in step 1; ΔT is the temperature difference between the two measurements.

[0045] Step 4: Subtract the coordinates before deformation from the corrected coordinates of the calibration point to determine whether the measured data is within the allowable error range.

[0046] In the present invention, the step three not only takes into account the influence of the thermal expansion coefficients of different materials, but also takes into account the influence of the anchor point position.

[0047] In the present invention, the influence of the anchor point position is reflected in the compensation coefficient γ = α2ΔTu F2 +α1ΔT(u F1 -u F2 )middle.

[0048] In the present invention, the proportional factor in step 3 is It is only related to the thermal expansion coefficient of the temperature compensation plate and the changing temperature.

[0049] The present invention provides a temperature compensation calculation method and device for a laser tracker used for tool measurement. The theoretical basis for its implementation is shown in Figure 1 .

[0050] Figure 1 The plate 1 and plate 2 have thermal expansion coefficients of α1 and α2 respectively. The plate 1 is anchored to the foundation, and the initial coordinates of the anchor point are u F1 ; Plate 2 and plate 1 are anchored, and the initial coordinates of the anchor points are u F2 The initial coordinate of the calibration point is u0. Assuming that the temperature change is ΔT and the coordinate of the calibration point after thermal deformation is u, we have:

[0051] u=u0+α1ΔT(u F2 -u F1 )+α2ΔT(u0-u F2 )

[0052] Right now:

[0053]

[0054] The above formula means that to eliminate the thermal deformation of the calibration point, the deformed coordinate u of the calibration point must first be compensated by γ and then multiplied by the proportionality factor β. In actual measurement, due to factors such as assembly stress and measurement error, the corrected u will usually not be completely consistent with u0. Therefore, the correction formula for u should be written as:

[0055]

[0056] On this basis, this embodiment takes a typical frame-type large assembly tool as the research object, such as Figure 2 As shown, the feasibility and accuracy of the calculation method of the present invention are verified by finite element simulation, which includes the following steps:

[0057] Step 1: Establish a geometric model of a large-scale frame assembly tool;

[0058] Step 2: Divide the grid, set boundary conditions, and set the overall temperature to change by 10°C;

[0059] Step 3: extract the coordinates of the calibration points before and after deformation;

[0060] Step 4: Correct the deformed coordinates of the calibration points using the correction method proposed in the present invention;

[0061] Step 5: Compare the corrected coordinates of the calibration points with the coordinates before and after deformation.

[0062] Figure 3The coordinates of the calibration points before, after, and after deformation are displayed. The results demonstrate that the temperature compensation calculation method proposed in this invention effectively eliminates thermal deformation caused by temperature changes. The coordinates after eliminating temperature effects are essentially consistent with the initial coordinates, demonstrating the feasibility and effectiveness of this invention.

[0063] The above specific implementation methods are detailed descriptions of the present invention. It cannot be considered that the specific implementation methods of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, they can make several simple deductions and substitutions without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A temperature compensation calculation method for a laser tracker used for tooling measurement, characterized in that: The assembly tool to be tested includes: a main frame and a temperature compensation plate; the method includes: Step 1: Use a laser tracker to measure the coordinates of the calibration points and anchor points on the assembly tooling, and record the ambient temperature of this measurement; the anchor points include: the anchor point of the main frame relative to the foundation and the anchor point of the temperature compensation plate relative to the main frame; the calibration points are set on the temperature compensation plate; Step 2: When the ambient temperature changes, the laser tracker is used to measure the coordinates of the calibration point and the anchor point again, and the ambient temperature of this measurement is recorded; Step 3: Correct the coordinates in step 2 using the following temperature compensation formula to eliminate thermal deformation caused by ambient temperature changes; u′=β(u+γ); Where u is the coordinate of the calibration point after temperature change, and the calibration point is any calibration point on the temperature compensation board; u′ is the coordinate value of u after correction; is the proportional factor; γ=α2ΔTu F2 +α1ΔT(u F1 -u F2 ) is the compensation coefficient; α1 and α2 are the thermal expansion coefficients of the main frame and the temperature compensation plate respectively; u F1 、u F2 are the coordinates of the main frame anchor point and the temperature compensation plate anchor point in step 1; ΔT is the temperature difference between the two measurements.

2. The temperature compensation calculation method for a laser tracker for tooling measurement according to claim 1, characterized in that: Also includes: Step 4: Subtract the coordinates of the calibration point in step 1 from the coordinates corrected in step 3, and the difference is used to determine whether the measured data is within the allowable error range.

3. The temperature compensation calculation method for a laser tracker used for tooling measurement according to claim 1, characterized in that: The calibration points are arranged along the length of the temperature compensation plate.

4. The temperature compensation calculation method for a laser tracker used for tooling measurement according to claim 1, characterized in that: The length of the temperature compensation plate shall not be less than 10 meters.

5. A temperature compensation calculation device for a laser tracker used for tooling measurement, characterized in that: The tooling under test includes: a main frame and a temperature compensation plate; the device includes: The first measurement module is used to measure the coordinates of the calibration points and anchor points on the assembly tool using a laser tracker, and record the ambient temperature of the measurement; the anchor points include: the anchor point of the main frame relative to the foundation and the anchor point of the temperature compensation plate relative to the main frame; the calibration points are set on the temperature compensation plate; The second measurement module is used to measure the coordinates of the calibration point and the anchor point again using the laser tracker when the ambient temperature changes, and record the ambient temperature of this measurement; A correction module, used to correct the coordinates in the second measurement module using the following temperature compensation formula, thereby eliminating thermal deformation caused by changes in ambient temperature; u′=β(u+γ); Where u is the coordinate of the calibration point after temperature change, and the calibration point is any calibration point on the temperature compensation board; u′ is the coordinate value of u after correction; is the proportional factor; γ=α2ΔTu F2 +α1ΔT(u F1 -u F2 ) is the compensation coefficient; α1 and α2 are the thermal expansion coefficients of the main frame and the temperature compensation plate respectively; u F1 、u F2 are the coordinates of the main frame anchor point and the temperature compensation plate anchor point in step 1; ΔT is the temperature difference between the two measurements.

6. The device according to claim 5, characterized in that Also includes: The judgment module is used to calculate the difference between the coordinates of the calibration point after correction and the coordinates before deformation, and to judge whether the measurement data is within the allowable error range.

7. A computer-readable storage medium, characterized in that include: memory and processor; The memory is configured to store executable instructions; The processor is configured to implement the method according to any one of claims 1 to 4 when executing the executable instructions stored in the memory.

8. A computer program product, characterized in that The computer program product comprises instructions, and when the instructions are executed by a computer, the method according to any one of claims 1 to 4 is implemented.

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