An Error Compensation Method for a Large-Span Laser Horizontal Ranging System

Abstract

This invention belongs to the field of plastic processing technology and discloses a method for compensating system errors in a large-span laser horizontal ranging system. The method involves measuring a long-axis component by mounting a laser ranging sensor on the component, allowing the sensor to move axially along the component. The long-axis component is then rotated axially to 0°. A reflector is installed on the laser ranging sensor, aligning the laser beam path downwards. A water tank is installed at the laser projection position, containing a liquid or thin film that reflects the laser beam. The laser ranging sensor is used to measure the liquid or thin film. Finally, the long-axis component is rotated axially to 90°, the reflector is removed from the laser ranging sensor, and the gravity direction error is measured. Measurements are then taken on the liquid or thin film, and the difference is calculated to obtain the system error Δa in the gravity direction when the long-axis component is at 90°. 90n Rotate the beam 180° to align the laser beam with gravity downwards, measure the liquid or liquid film, and calculate the systematic error Δa of gravity downwards when the long axis component is at 180°. 180n Finally, data processing is performed to calculate the error of the ranging system. This invention, by using a horizontal ranging method to detect the straightness of a product, can further reduce the error in the measured data caused by the bending deformation of the measured parts and the measuring system due to their own weight. Assembly is simpler, parts do not require high-precision machining, and the assembly process does not require high-precision adjustment, significantly reducing the manufacturing cost and cycle time of the measuring system.

Description

Technical Field

[0001] This invention belongs to the field of plastic processing technology, and relates to a plastic processing method through extrusion deformation, specifically to an error compensation method for a large-span laser horizontal ranging system. Background Technology

[0002] Straightness measurement of shaft parts generally employs a contact measurement method. This involves placing both ends or other parts of the object to be measured on a V-block, pressing the probe of a dial indicator onto the object, rotating the part along its axis, and recording the range of pointer movement on the scale. After repeating the dial indicator measurements at multiple locations and conducting a comprehensive evaluation, the straightness can be obtained. However, the accuracy of this method is affected by the density of measurement points. Traditional measurement techniques struggle to accurately evaluate the true straightness of the measured part and cannot measure the straightness of non-rotating bodies. In recent years, with the rapid development of advanced measurement technologies, laser ranging technology has been widely applied in aerospace, metallurgical forging, geological exploration, and other fields. Laser ranging can perform measurement tasks in harsh environments such as extreme temperatures and pressures, and is easily used for high-density, digital, and automated measurement tasks, making it one of the irreplaceable measurement technologies currently available.

[0003] Because weakly rigid shaft parts undergo bending deformation in the direction of gravity during measurement, and contact measurement methods introduce disturbance to the measured part, easily affecting the measurement results. However, using laser horizontal ranging to measure the highest point of the side of such parts eliminates the influence of the part's own bending deformation on measurement accuracy. This non-contact measurement technology avoids disturbance to the measured part, allowing the measurement data to more accurately reflect the surface fluctuations. Rotating the measured part along the axial direction enables three-dimensional surface measurement, resulting in a larger data sample and more reliable measurement results.

[0004] Especially when the part being measured is a non-rotating body, it can no longer be measured using traditional rotary measurement methods. The measurement process must be carried out along the axial direction. Traditional contact measurement cannot form a complete straightness measurement, and coordinate measuring machine (CMM) must be used. Using CMM is not only cumbersome and not suitable for large-scale rapid measurement, but also expensive because it is charged based on the number of measurement points.

[0005] The main reason why it is difficult to achieve high-precision calibration of large-span laser horizontal ranging systems is that the structural rigidity of large-span systems is reduced, the assembly difficulty of large-size components is increased, and large-size standard measuring tools are difficult to process and use. The error compensation technology of horizontal measurement systems is much more difficult than that of vertical systems, as detailed below.

[0006] First, there's the impact of large-span distance measurement on structural rigidity. As the distance measurement span increases, to ensure the linear guide rail supporting the laser distance sensor has excellent straightness, the rigidity of the beam structure must be strengthened. This can be achieved by using higher-performance materials for the beam, increasing the beam's cross-sectional dimensions, or optimizing the beam's structure. All these methods increase the material or manufacturing costs of the beam.

[0007] Secondly, there is the impact of large-span ranging on system assembly errors. As the size of system components increases, machining accuracy decreases, making it difficult to adjust the overall accuracy during assembly. This results in a decline in the overall system accuracy. To maintain good measurement accuracy, high-precision machine tools must be used, or the accuracy must be downgraded, both of which affect the widespread application of laser horizontal ranging.

[0008] Thirdly, the impact of large-span distance measurement on standard measuring instruments. A common and frequently used method is to use high-hardness materials to make standard measuring instruments. These instruments possess straightness or flatness far exceeding that of the measurement system and are essentially non-plastic, making them resistant to deformation over long-term storage. These standard instruments are typically made of materials such as marble and high-hardness steel. Their disadvantages include high manufacturing costs, heavy weight, difficulty in storage and transportation, and cumbersome calibration processes.

[0009] Fourthly, there is the impact of long-span distance measurement on the calibration direction. Since rigid standard gauges are unsuitable for calibration of long-span distance measuring equipment, liquids or liquid films are sometimes used as standard gauges. Due to gravity and their own fluidity, the surface of a liquid or liquid film can remain horizontal for a long time, which can be considered absolutely horizontal in engineering. Using liquids or liquid films allows for low-cost calibration of laser distance measurement in the gravity direction for long-span distance measurement. However, because laser distance measurement calibration requires the laser to be approximately perpendicular to the standard gauge, liquids or liquid films cannot directly meet the requirements for horizontal laser distance measurement calibration. Summary of the Invention

[0010] To address the aforementioned issues, this invention provides an error compensation method for a large-span laser horizontal ranging system. By optimizing the system error compensation algorithm, using a liquid or liquid film as a standard measuring instrument for measurement, and processing the measurement data, the compensation amount is incorporated into the system. This enables high-efficiency, low-cost, and high-precision horizontal straightness measurement of large-size, weakly rigid shaft-type parts containing non-rotating bodies.

[0011] The technical solution of the present invention is as follows:

[0012] An error compensation method for a large-span laser horizontal ranging system, used for measuring long-axis parts, includes the following steps:

[0013] S1, The laser rangefinder is mounted on the long shaft part, and the laser rangefinder can move axially on the long shaft part;

[0014] S2, rotate the long shaft part axially to 0°, install a reflector on the laser rangefinder, and turn the laser beam path of the laser rangefinder so that gravity is downward. Install a water tank at the laser projection position, and fill the water tank with a liquid or liquid film that can reflect laser light; use the laser rangefinder to measure the liquid or liquid film to obtain (a 0n 、b 0n ), where a is the laser path length, b is the axial position of the laser rangefinder, subscript 0 represents 0°, and subscript n represents the nth point of the laser rangefinder on the long axis part with the measurement pitch as the interval;

[0015] S3, rotate the long-axis part axially to 90°, remove the reflector from the laser rangefinder sensor, and measure the gravity direction error. After measuring the liquid or liquid film, obtain (a 90n 、b 90n ), the subscript 90 indicates 90°; use a 90n Each number in the sequence and a 90n The minimum value a in the sequence 90nmin By subtracting the values, when the long shaft part is 90°, b 90n System error Δa in the direction of gravity at the location 90n That is, Δa 90n =a 90n -a 90nmin ;

[0016] S4, rotate the beam 180°, install the reflector on the laser rangefinder sensor, and redirect the laser beam downwards to align with gravity, performing a horizontal reverse error measurement; after measuring the liquid or liquid film, obtain (a 180n 、b 180n The subscript 180 indicates 180°; use a 180n Each number in the sequence and a 180n The minimum value a in the sequence 180nmin By taking the difference, we obtain b when the beam is 180°. 180n The systematic error Δa of gravity downwards at the location 180n , that is, Δa 180n =a 180n -a 180nmin ;

[0017] S5, data processing, calculates the error of the ranging system.

[0018] Furthermore, the specific methods for data processing in S5 include:

[0019] When the beam is at 0°, b 0n In terms of position,

[0020] h 0垂 =h 0垂装 +h 弯 =Δa 0n =a 0n -a 0nmin (1)

[0021] When the beam is at 90°, b 90n In terms of position,

[0022] h 90水 =h 90水装 +h 弯 =Δa 90n =a 90n -a 90nmin (2)

[0023] When the beam is at 180°, b 180n In terms of position,

[0024] h 180垂 =h 180垂装 +h 弯 =-h 0垂装 +h 弯 =Δa 180n =a 180n -a 180nmin (3)

[0025] Add equation (3) to equation (1).

[0026] h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 )

[0027] Because h → 0垂装 =-h → 180垂装

[0028] Therefore h 弯 =1 / 2(h 0垂 +h 180垂 ) = 1 / 2 (Δa) 0n +Δa 180n (4)

[0029] Substitute equation (4) into equation (2).

[0030] h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa) 0n +Δa180n )

[0031] h represents error; the subscript h (water) represents horizontal error; the subscript h (vertical) represents vertical error; the subscript h (bend) represents bending error; the subscript h (water assembly) represents horizontal assembly error; the subscript h (vertical assembly) represents vertical assembly error; the superscript h (arrow) represents a vector.

[0032] Laser rangefinder in b n The system compensation value for horizontal distance measurement is h. 水装 =h 90水装 =Δa 90n -1 / 2(Δa) 0n +Δa 180n The horizontal ranging system is compensated point by point based on the measurement pitch.

[0033] Furthermore, the laser rangefinder is mounted on a slider, which is mounted on a linear guide rail. The slider is also mounted on an adapter, which is mounted on a lead screw nut. The lead screw nut is mounted on a lead screw parallel to the linear guide rail. The lead screw is connected to a servo motor. The position of the laser rangefinder on the linear guide rail is controlled by controlling the left and right rotation of the servo motor. The linear guide rail is mounted on a long shaft component.

[0034] Furthermore, the long shaft parts are mounted in bearings at both ends, and the bearings are mounted on the bed.

[0035] Furthermore, the method for obtaining the measurement pitch is as follows: With the long shaft part at 0°, the laser rangefinder emits a linear laser beam horizontally, forming a diffuse reflection on the long shaft part as a bright line segment. The high point of the part being measured is placed within the scanning range of this bright line segment. The distance values ​​from the laser rangefinder to several points within the bright line segment are detected, and the minimum value among these distance values ​​is obtained as the measurement pitch. This method is repeated to obtain (a n 、b n All measured pitches.

[0036] Furthermore, the water tank is first allowed to stand still to eliminate ripples on the reflective surface, and the water tank and the liquid or liquid film inside the water tank do not move during the entire measurement process.

[0037] Furthermore, unilateral measurement compensation is performed based on system error: the long axis part is rotated to 0°, and the laser rangefinder emits a linear laser in the horizontal direction; the laser forms diffuse reflection on the long axis part, appearing as a bright line segment; the high point of the part being measured is placed within the scanning range of the bright line segment, and the distance values ​​from several points within the bright line segment to the laser rangefinder are detected, thereby obtaining the minimum value among these distance values, denoted as a1; simultaneously, based on the rotation speed of the servo motor, the position b1 of the laser rangefinder is calculated; the position of the laser rangefinder on the long axis part of the crossbeam is adjusted, and the above ranging action is repeated to obtain (a2, b2) to (a max 、bmax );(a max 、b max (a) represents the measured data. n +Δa 90n -1 / 2 (Δ a0n +Δa 180n b n Calculate the straightness of the long shaft parts.

[0038] Furthermore, three-dimensional measurement compensation is performed based on the system error: rotate the long shaft part by a certain angle and repeat step S5 to obtain the straightness of the long shaft part at multiple angles.

[0039] The beneficial effects of the present invention are as follows:

[0040] 1. The error compensation method of the large-span laser horizontal ranging system described in this invention, by using horizontal ranging to detect the straightness of the product, can further reduce the error of the measured data caused by the bending deformation of the measured parts and the measuring system due to their own weight. The measurement principle is scientific, the measurement accuracy is higher, and the cost increase caused by increasing the rigidity of the beam structure is avoided.

[0041] 2. The error compensation method for a large-span laser horizontal ranging system described in this invention is simpler to assemble, requires no high-precision machining of parts, and does not require high-precision adjustment during the assembly process, which greatly reduces the manufacturing cost and manufacturing cycle of the measurement system.

[0042] 3. The error compensation method for a large-span laser horizontal ranging system described in this invention does not require a high-rigidity, overall standard measuring instrument. Instead, it uses a low-cost liquid or liquid film surface as the standard measuring instrument. The system itself is compensated through multi-angle measurements, which facilitates the formation of an automated compensation program. It has low application cost, high measurement accuracy, convenient use, and strong reliability. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this invention, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0044] Figure 1 A side view schematic diagram of the horizontal compensation of the crossbeam at 0° for the invention;

[0045] Figure 2 A side view schematic diagram of the invention's crossbeam located at 90° for vertical compensation;

[0046] Figure 3A side view of the crossbeam of the invention located at 180° with reverse horizontal compensation;

[0047] Figure 4 A side view schematic diagram of the laser level measurement principle of the invention;

[0048] 1. Laser rangefinder; 2. Adapter; 3. Slider; 4. Linear guide; 5. Lead screw nut; 6. Lead screw; 7. Crossbeam; 8. Bearing; 9. Laser; 10. Water tank; 11. Liquid or liquid film; 12. Measured part; 13. Drive wheel; 14. Driven wheel; 15. Reflector. Detailed Implementation

[0049] This section describes embodiments of the present invention, used to explain and illustrate the technical solutions of the present invention. Unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0050] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating directions or positional relationships, are given in the accompanying drawings and are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or device referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include more than one of those features. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0051] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integrated connection; they can refer to a mechanical connection or a point connection; they can refer to a direct connection or a connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] Example 1:

[0053] An error compensation method for a large-span laser horizontal ranging system, used for measuring long-axis parts, includes the following steps:

[0054] S1, The laser rangefinder is mounted on the long shaft part, and the laser rangefinder can move axially on the long shaft part;

[0055] S2, rotate the long shaft part axially to 0°, install a reflector on the laser rangefinder, and turn the laser beam path of the laser rangefinder so that gravity is downward. Install a water tank at the laser projection position, and fill the water tank with a liquid or liquid film that can reflect laser light; use the laser rangefinder to measure the liquid or liquid film to obtain (a 0n 、b 0n ), where a is the laser path length, b is the axial position of the laser rangefinder, subscript 0 represents 0°, and subscript n represents the nth point of the laser rangefinder on the long axis part with the measurement pitch as the interval;

[0056] S3, rotate the long-axis part axially to 90°, remove the reflector from the laser rangefinder sensor, and measure the gravity direction error. After measuring the liquid or liquid film, obtain (a 90n 、b 90n ), the subscript 90 indicates 90°; use a 90n Each number in the sequence and a 90n The minimum value a in the sequence 90nmin By subtracting the values, when the long shaft part is 90°, b 90n System error Δa in the direction of gravity at the location 90n That is, Δa 90n =a 90n -a 90nmin ;

[0057] S4, rotate the beam 180°, install the reflector on the laser rangefinder sensor, and redirect the laser beam downwards to align with gravity, performing a horizontal reverse error measurement; after measuring the liquid or liquid film, obtain (a 180n 、b 180n The subscript 180 indicates 180°; use a 180n Each number in the sequence and a 180n The minimum value a in the sequence 180nmin By taking the difference, we obtain b when the beam is 180°. 180n The systematic error Δa of gravity downwards at the location 180n , that is, Δa 180n =a 180n -a 180nmin ;

[0058] S5, data processing, calculates the error of the ranging system.

[0059] The specific methods for data processing in S5 include:

[0060] When the beam is at 0°, b 0n In terms of position,

[0061] h 0垂 =h 0垂装 +h弯 =Δa 0n =a 0n -a 0nmin (1)

[0062] When the beam is at 90°, b 90n In terms of position,

[0063] h 90水 =h 90水装 +h 弯 =Δa 90n =a 90n -a 90nmin (2)

[0064] When the beam is at 180°, b 180n In terms of position,

[0065] h 180垂 =h 180垂装 +h 弯 =-h 0垂装 +h 弯 =Δa 180n =a 180n -a 180nmin (3)

[0066] Use formula (1) plus formula (3).

[0067] h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 )

[0068] Because h → 0垂装 =-h → 180垂装

[0069] Therefore h 弯 =1 / 2(h 0垂 +h 180垂 ) = 1 / 2 (Δa) 0n +Δa 180n (4)

[0070] Substitute formula (4) into formula (2).

[0071] h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa) 0n +Δa 180n )

[0072] h represents error; the subscript h (water) represents horizontal error; the subscript h (vertical) represents vertical error; the subscript h (bend) represents bending error; the subscript h (water assembly) represents horizontal assembly error; the subscript h (vertical assembly) represents vertical assembly error; the superscript h (arrow) represents a vector.

[0073] Laser rangefinder in b n The system compensation value for horizontal distance measurement is h. 水装 =h 90水装 =Δa 90n -1 / 2(Δa) 0n +Δa 180n The horizontal ranging system is compensated point by point based on the measurement pitch.

[0074] The laser rangefinder is mounted on a slider, which is mounted on a linear guide rail. The slider is also mounted on an adapter, which is mounted on a lead screw nut. The lead screw nut is mounted on a lead screw parallel to the linear guide rail. The lead screw is connected to a servo motor. The position of the laser rangefinder on the linear guide rail is controlled by controlling the left and right rotation of the servo motor. The linear guide rail is mounted on a long shaft component.

[0075] The long shaft part is mounted in bearings at both ends, and the bearings are mounted on the bed.

[0076] The method for obtaining the measurement pitch is as follows: With the long shaft part at 0°, the laser rangefinder emits a linear laser beam horizontally, creating a diffuse reflection on the long shaft part as a bright line segment. The highest point of the part being measured is placed within the scanning range of this bright line segment. The distance values ​​from the laser rangefinder to several points within the bright line segment are detected, and the minimum value among these distance values ​​is obtained as the measurement pitch. This method is repeated to obtain (a... n 、b n All measured pitches.

[0077] The water tank is first allowed to stand still to eliminate ripples on the reflective surface, and the water tank and the liquid or liquid film inside the water tank do not move during the entire measurement process.

[0078] Single-sided measurement compensation is performed based on system error: The long axis part is rotated to 0°, and the laser rangefinder emits a linear laser in the horizontal direction; the laser forms diffuse reflection on the long axis part, appearing as a bright line segment; the high point of the part being measured is placed within the scanning range of the bright line segment, and the distance values ​​from several points within the bright line segment to the laser rangefinder are detected, thus obtaining the minimum value among these distance values, denoted as a1; simultaneously, based on the rotation speed of the servo motor, the position b1 of the laser rangefinder is calculated; the position of the laser rangefinder on the long axis part of the crossbeam is adjusted, and the above ranging action is repeated to obtain (a2, b2) to (a max 、b max );(a max 、b max (a) represents the measured data.n +Δa 90n -1 / 2 (Δ a0n +Δa 180n b n Calculate the straightness of the long shaft parts.

[0079] Three-dimensional measurement compensation based on system error: Rotate the long shaft part by a certain angle and repeat step S5 to obtain the straightness of the long shaft part at multiple angles.

[0080] Example 2:

[0081] An error compensation method for a large-span laser horizontal ranging system.

[0082] The laser rangefinder sensor is mounted on a slider, which is mounted on a linear guide rail. The slider is also mounted on an adapter, which is mounted on a lead screw nut. The lead screw nut is mounted on a lead screw parallel to the linear guide rail. The lead screw is connected to a servo motor. By controlling the left and right rotation of the servo motor and precisely controlling its position characteristics, the position of the laser rangefinder sensor on the linear guide rail can be accurately controlled. The linear guide rail is mounted on a rotatable crossbeam. Both ends of the crossbeam are mounted in bearings, which are mounted on the machine bed. The crossbeam can be rotated manually or by motor drive, and can be fixed at positions of 0°, 90°, and 180° relative to the initial position.

[0083] The main errors in the ranging system include: measurement errors of the laser ranging sensor itself, mechanical assembly errors of all components, and beam bending errors. It is important to note that the error compensation range involved in this invention does not include the measurement error of the laser ranging sensor itself. Furthermore, the horizontal ranging scheme has eliminated the influence of gravity on the measurement system; that is, the gravity component of the mechanical assembly errors of all components and the beam bending error are excluded. The system error referred to in this invention only includes the horizontal component of the mechanical assembly errors of the components.

[0084] Utilizing the influence of gravity and the fluidity of liquids or thin films, their surfaces can remain horizontal for extended periods, which can be considered absolutely horizontal in engineering. Furthermore, the reflective properties of optical elements such as internal reflecting prisms or front-surface coated mirrors can alter the optical path without causing optical path decomposition. This facilitates the conversion of horizontal laser light into vertical laser light and avoids interference with measurement data caused by optical path decomposition. The crossbeam is made of uniform metal and is equipped with numerous components. By adjusting the counterweight, the center of gravity of each section of the measurement system is positioned on the central axis of the crossbeam's rotation, ensuring that the crossbeam's bending state is consistent at 0°, 90°, and 180°.

[0085] Rotate the crossbeam to 0°; this is the working position. The laser rangefinder emits a line laser in the horizontal direction. The line laser causes diffuse reflection on the part being measured, appearing as a bright line segment. During measurement, place the highest point of the part being measured within the scanning range of the bright line segment. This allows the detection of the distance values ​​from several points within the line segment to the laser rangefinder, thus obtaining the minimum value among these distances, denoted as a1. Simultaneously, based on the servo motor's rotation speed, convert this to the laser rangefinder's position b1. Adjust the laser rangefinder's position on the crossbeam and repeat the above ranging action to obtain (a2, b2), ..., (a... n 、b n ). with (a n 、b n The coordinates () represent the coordinates, which can be used to calculate or describe the straightness of the measured part. However, the straightness at this point has not yet been compensated for errors. To accurately compensate the measured data, the following steps are required:

[0086] When performing horizontal error compensation measurements at the 0° position of the measurement system, a reflector is mounted on the laser rangefinder to redirect the laser beam path to the vertical direction. A water tank is installed at the online laser projection position, and a liquid or liquid film that can reflect the laser beam is placed inside the tank, ensuring that the laser beam is projected completely onto the liquid or liquid film. The tank is then allowed to settle to eliminate ripples on the reflective surface. The water tank should be large enough that it and the liquid or liquid film within it do not move during subsequent measurements. After measuring the liquid or liquid film, the obtained (a) 0n 、b 0n That is, when the beam is at 0°, the laser rangefinder is at position b. 0n At that time, the laser path length a 0n Use a 0n With a 0n Minimum value a in the sequence 0nmin By taking the difference, we can obtain the beam at the 0° position, b 0n System error Δa in the direction of gravity at the location 0n , that is, Δa 0n =a 0n -a 0nmin 'n' represents the installation distance of the laser rangefinder sensor along the axial direction of the beam, therefore 'a'... 0n With b 0n It is a sequence of numbers whose values ​​of n vary.

[0087] Rotate the beam to 90°, which is the vertical error compensation position. Remove the reflector from the laser rangefinder sensor and measure the gravity direction error of the measurement system. After measuring the liquid or liquid film, obtain (a 90n 、b 90n That is, when the laser rangefinder is in position b 90n At that time, the laser path length a 90n Use a90n With a 90n The minimum value a in the sequence 90nmin By taking the difference, we can obtain b when the beam is at 90°. 90n System error Δa in the direction of gravity at the location 90n , that is, Δa 90n =a 90n -a 90nmin .

[0088] Rotate the crossbeam 180° to the reverse horizontal error compensation position. Install the reflector on the laser rangefinder sensor to align the laser beam path with the direction of gravity, and perform a horizontal reverse error measurement on the measurement system. After measuring a liquid or liquid film, obtain (a 180n 、b 180n That is, when the laser rangefinder is in position b 180n At that time, the laser path length a 180n Use a 180n With a 180n The minimum value a in the sequence 180nmin By taking the difference, we can obtain b when the beam is 180°. 180n System error Δa in the direction of gravity at the location 180n , that is, Δa 180n =a 180n -a 180nmin .

[0089] Because the cosine function COS1° = 0.999847, meaning that when the laser is irradiated horizontally or vertically, the measured laser path is very close to the absolute horizontal and the direction of gravity. In this invention, "horizontal" and "absolute horizontal," and "vertical" and "direction of gravity" have the same meaning in mathematical calculations. Assuming that the assembly gap between each moving component is 0 during assembly, meaning there is no system play when the beam is at 0°, 90°, and 180°. The error h in the horizontal direction... 水 It consists of mechanical assembly errors in the horizontal direction, while the error h in the vertical direction... 垂 It consists of mechanical assembly errors in the vertical direction and bending errors in the crossbeam. Therefore, h... 水 =h 水装 h 垂 =h 垂装 +h 垂弯 If the beam's bending deformation is consistent at 0°, 90°, and 180°, then h → 0垂弯 =-h → 180垂弯 h 弯 =h 垂弯 =h 水弯 .

[0090] When the beam is at 0°, b 0n In terms of position,

[0091] h 0垂 =h 0垂装 +h 弯 =Δa 0n =a 0n -a 0nmin (1)

[0092] When the beam is at 90°, b 90n In terms of position,

[0093] h 90水 =h 90水装 +h 弯 =Δa 90n =a 90n -a 90nmin (2)

[0094] When the beam is at 180°, b 180n In terms of position,

[0095] h 180垂 =h 180垂装 +h 弯 =-h 0垂装 +h 弯 =Δa 180n =a 180n -a 180nmin (3)

[0096] Use formula (1) plus formula (3).

[0097] h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 )

[0098] Because h → 0垂装 =-h → 180垂装

[0099] Therefore h 弯 =1 / 2(h 0垂 +h 180垂 ) = 1 / 2 (Δa) 0n +Δa 180n (4)

[0100] Substitute formula (4) into formula (2).

[0101] h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa) 0n +Δa180n )

[0102] Since the assembly error does not change with the rotation angle of the crossbeam, the laser rangefinder sensor can operate at b... n The system compensation value for horizontal distance measurement should be h. 水装 =h 90水装 =Δa 90n -1 / 2(Δa) 0n +Δa 180n The horizontal ranging system can be compensated point by point based on the measurement pitch.

[0103] The technical solution of this invention: an error compensation method for a large-span laser horizontal ranging system, comprising the following specific steps:

[0104] 1. Rotate the crossbeam to 0° (axial rotation angle), install a reflector on the laser rangefinder sensor, and steer the laser beam path to the vertical direction. Install a water tank at the online laser projection position, and fill the tank with a liquid or liquid film that can reflect the laser beam, ensuring the laser line is completely projected onto the liquid or liquid film. Allow it to stand still to eliminate ripples on the reflective surface. The water tank should be large enough that the tank and the liquid or liquid film within it will not move during subsequent measurements. After measuring the liquid or liquid film, obtain (a 0n 、b 0n That is, when the beam is at 0°, the laser rangefinder is at position b. 0n At that time, the laser path length a 0n Use a 0n With a 0n Minimum value a in the sequence 0nmin By taking the difference, we can obtain the beam at the 0° position, b 0n System error Δa in the direction of gravity at the location 0n , that is, Δa 0n =a 0n -a 0nmin .

[0105] 2. Rotate the beam 90°, remove the reflector from the laser rangefinder sensor, and measure the gravity direction error of the measurement system. After measuring the liquid or liquid film, obtain (a 90n 、b 90n That is, when the laser rangefinder is in position b 90n At that time, the laser path length a 90n Use a 90n With a 90n The minimum value a in the sequence 90nmin By taking the difference, we can obtain b when the beam is at 90°. 90n System error Δa in the direction of gravity at the location 90n , that is, Δa 90n =a 90n -a90nmin .

[0106] 3. Rotate the crossbeam 180°, install the reflector on the laser rangefinder sensor, and align the laser beam path with the direction of gravity. Perform a horizontal reverse error measurement on the measurement system. After measuring a liquid or liquid film, obtain (a 180n 、b 180n That is, when the laser rangefinder is in position b 180n At that time, the laser path length a 180n Use a 180n With a 180n The minimum value a in the sequence 180nmin By taking the difference, we can obtain b when the beam is 180°. 180n System error Δa in the direction of gravity at the location 180n , that is, Δa 180n =a 180n -a 180nmin .

[0107] 4. Data processing. Horizontal error h 水 It consists of mechanical assembly errors in the horizontal direction, while the error h in the vertical direction... 垂 It consists of mechanical assembly errors in the vertical direction and bending errors in the crossbeam. Therefore, h... 水 =h 水装 h 垂 =h 垂装 +h 垂弯 The bending deformation of the beam at 0° and 180° is the same but in opposite directions, so h → 0垂弯 =-h → 180垂弯 .

[0108] When the beam is at 0°, b 0n In terms of position,

[0109] h 0垂 =h 0垂装 +h 弯 =Δa 0n =a 0n -a 0nmin (1)

[0110] When the beam is at 90°, b 90n In terms of position,

[0111] h 90水 =h 90水装 +h 弯 =Δa 90n =a 90n -a 90nmin (2)

[0112] When the beam is at 180°, b 180n In terms of position,

[0113] h 180垂 =h 180垂装 +h 弯 =-h 0垂装 +h 弯 =Δa 180n =a 180n -a 180nmin (3)

[0114] Use formula (1) plus formula (3).

[0115] h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 )

[0116] Because h → 0垂装 =-h → 180垂装

[0117] Therefore h 弯 =1 / 2(h 0垂 +h 180垂 ) = 1 / 2 (Δa) 0n +Δa 180n (4)

[0118] Substitute formula (4) into formula (2).

[0119] h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa) 0n +Δa 180n )

[0120] Since the assembly error does not change with the rotation angle of the crossbeam, the laser rangefinder sensor can operate at b... n The system compensation value for horizontal distance measurement should be h. 水装 =h 90水装 =Δa 90n -1 / 2(Δa) 0n +Δa 180n The horizontal ranging system can be compensated point by point based on the measurement pitch.

[0121] Example 3:

[0122] 1. System Composition. The laser rangefinder 1 is mounted on the adapter 2, the adapter 2 is mounted on the slider 3, the slider 3 is mounted on the linear guide rail 4, and the adapter 2 is mounted on the lead screw nut 5. The lead screw nut 5 is mounted on the lead screw 6 parallel to the linear guide rail 4. The lead screw 6 is directly driven by a servo motor. By controlling the left and right rotation of the servo motor and precisely controlling the position of the laser rangefinder 1 in the system, the linear guide rail 4 is mounted on a rotatable crossbeam 7. The two ends of the crossbeam 7 are mounted in bearings 8. The crossbeam 7 can rotate and can be fixed at positions of 0°, 90°, and 180° relative to the initial position.

[0123] 2. Rotate the crossbeam 7 to 0°, and install a reflector 15 on the laser rangefinder 1 to steer the light path of the laser 9 to the vertical direction. Install a water tank 10 at the laser projection position of the laser rangefinder 1, and fill the water tank 10 with a liquid or liquid film 11 that can reflect the laser, so that the laser 9 line segment is completely projected onto the liquid or liquid film 11. Let it stand to eliminate ripples on the reflective surface. The water tank 10 should be large enough so that the water tank 10 and the liquid or liquid film 11 inside the water tank do not move during subsequent measurements. After measuring the liquid or liquid film 11, the obtained (a 0n 、b 0n That is, when the crossbeam 7 is at the 0° position, the laser rangefinder 1 is at position b. 0n At that time, the laser path length a 0n Use a 0n With a 0n Minimum value a in the sequence 0nmin By taking the difference, we can obtain that beam 7 is at the 0° position, b 0n System error Δa in the direction of gravity at the location 0n , that is, Δa 0n =a 0n -a 0nmin .

[0124] 3. Rotate the crossbeam 7 to 90°, remove the reflector 15 from the laser rangefinder 1, and measure the gravity direction error of the measurement system. After measuring the liquid or liquid film 11, the obtained (a 90n 、b 90n That is, when laser rangefinder 1 is in position b 90n At that time, the laser path length a 90n Use a 90n With a 90n The minimum value a in the sequence 90nmin By taking the difference, we can obtain the value of b when the beam 7 is at 90°. 90n System error Δa in the direction of gravity at the location 90n , that is, Δa 90n =a 90n -a 90nmin .

[0125] 4. Rotate the crossbeam 7 180°, install the reflector 15 on the laser rangefinder 1, and redirect the light path of the laser 9 to the direction of gravity. Perform a horizontal reverse error measurement on the measurement system. After measuring the liquid or liquid film 11, obtain (a 180n 、b 180n That is, when laser rangefinder 1 is in position b 180n At that time, the laser path length a 180n Use a 180n With a 180n The minimum value a in the sequence 180nmin By taking the difference, we can obtain b when the beam is 180°. 180n System error Δa in the direction of gravity at the location 180n , that is, Δa 180n =a 180n -a 180nmin .

[0126] 5. Data processing. Horizontal error h 水 It consists of mechanical assembly errors in the horizontal direction, while the error h in the vertical direction... 垂 It consists of mechanical assembly errors in the vertical direction and bending errors of the crossbeam 7. Therefore, h... 水 =h 水装 h 垂 =h 垂装 +h 垂弯 The bending deformation of beam 7 at 0° and 180° is the same but in opposite directions. Therefore, h... → 0垂弯 =-h → 180垂弯 .

[0127] When beam 7 is at 0°, b 0n In terms of position,

[0128] h 0垂 =h 0垂装 +h 弯 =Δa 0n =a 0n -a 0nmin (1)

[0129] When beam 7 is at 90°, b 90n In terms of position,

[0130] h 90水 =h 90水装 +h 弯 =Δa 90n =a 90n -a 90nmin (2)

[0131] When beam 7 is at 180°, b180n In terms of position,

[0132] h 180垂 =h 180垂装 +h 弯 =-h 0垂装 +h 弯 =Δa 180n =a 180n -a 180nmin (3)

[0133] Use formula (1) plus formula (3).

[0134] h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 )

[0135] Because h → 0垂装 =-h → 180垂装

[0136] Therefore h 弯 =1 / 2(h 0垂 +h 180垂 ) = 1 / 2 (Δa) 0n +Δa 180n (4)

[0137] Substitute formula (4) into formula (2).

[0138] h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa) 0n +Δa 180n )

[0139] Since the assembly error does not change with the rotation angle of the crossbeam 7, the laser rangefinder 1 is in b n The system compensation value for horizontal distance measurement should be h. 水装 =h 90 Water content = Δa 90n -1 / 2(Δa) 0n +Δa 180n Based on the measured pitch, point-by-point compensation is performed on the horizontal ranging system, then a 0n +Δa 90n -1 / 2(Δa) 0n +Δa 180n That is, the actual measured value, which is in b. n The measured value at point a should be a n+Δa 90n -1 / 2 (Δ a0n +Δa 180n ).

[0140] 6. Single-sided actual measurement compensation. When using the system for laser horizontal measurement, the crossbeam 7 is rotated to 0°, and the laser rangefinder 1 emits a linear laser 9 in the horizontal direction. The laser 9 forms diffuse reflection on the measured part 12, appearing as a bright line segment. During measurement, the high point of the measured part 12 is placed within the scanning range of the bright line segment, and the distance values ​​of several points within the line segment from the laser rangefinder 1 can be detected, thus obtaining the minimum value among these distance values, denoted as a1. At the same time, based on the rotation speed of the servo motor, the position b1 of the laser rangefinder 1 is calculated. The position of the laser rangefinder 1 on the crossbeam 7 is adjusted, and the above ranging action is repeated to obtain (a2, b2), ..., (a... n 、b n ). (a n 、b n (a) represents measured data, which, after compensation, n +Δa 90n -1 / 2 (Δ a0n +Δa 180n b n This allows for the accurate calculation or description of the straightness of the measured part 12.

[0141] 7. Overall Measurement and Compensation. Under the rotational force of the drive wheel 12 and the supporting force of the driven wheel 13, the part to be measured is rotated by a certain angle. By repeating step 5, the straightness of the part to be measured at multiple angles can be obtained, and the overall straightness of the part to be measured can be judged.

Claims

1. An error compensation method for a large-span laser horizontal ranging system, used for measuring long-axis parts, characterized in that... Includes the following steps: S1, The laser rangefinder is mounted on the long shaft part, and the laser rangefinder can move axially on the long shaft part; S2, rotate the long shaft part axially to 0°, install a reflector on the laser rangefinder, and turn the laser beam path of the laser rangefinder so that gravity is downward. Install a water tank at the laser projection position, and fill the water tank with a liquid or liquid film that can reflect laser light; use the laser rangefinder to measure the liquid or liquid film to obtain (a 0n b 0n ), where a is the laser path length, b is the axial position of the laser rangefinder, subscript 0 represents 0°, and subscript n represents the nth point of the laser rangefinder on the long axis part with the measurement pitch as the interval; S3, rotate the long-axis part axially to 90°, remove the reflector from the laser rangefinder sensor, and measure the gravity direction error. After measuring the liquid or liquid film, obtain (a 90n b 90n ), the subscript 90 indicates 90°; use a 90n Each number in the sequence and a 90n The minimum value a in the sequence 90nmin By subtracting the values, when the long shaft part is 90°, b 90n System error Δa in the direction of gravity at the location 90n That is, Δa 90n =a 90n -a 90nmin ; S4, rotate the beam 180°, install the reflector on the laser rangefinder sensor, and redirect the laser beam downwards to align with gravity, performing a horizontal reverse error measurement; after measuring the liquid or liquid film, obtain (a 180n b 180n The subscript 180 indicates 180°; use a 180n Each number in the sequence and a 180n The minimum value a in the sequence 180nmin By taking the difference, we obtain b when the beam is 180°. 180n The systematic error Δa of gravity downwards at the location 180n That is, Δa 180n =a 180n -a 180nmin ; S5, data processing, calculates the error of the ranging system.

2. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, The specific methods for data processing in S5 include: When the beam is at 0°, b 0n In terms of position, h 0垂 =h 0垂装 + h 弯 =Δa 0n =a 0n -a 0nmin (1) When the beam is at 90°, b 90n In terms of position, h 90水 =h 90水装 + h 弯 =Δa 90n =a 90n -a 90nmin (2) When the beam is at 180°, b 180n In terms of position, h 180垂 =h 180垂装 + h 弯 =-h 0垂装 + h 弯 =Δa 180n =a 180n -a 180nmin (3) Use formula (1) plus formula (3). h 0垂 +h 180垂 =(h 0垂装 +h 弯 )+(h 180垂装 +h 弯 ) Because h → 0垂装 =-h → 180垂装 So h 弯 = 1 / 2(h 0垂 + h 180垂 ) = 1 / 2(Δa 0n + Δa 180n ) (4) Substitute formula (4) into formula (2). h 90水装 =Δa 90n -h 弯 =Δa 90n -1 / 2(Δa 0n +Δa 180n ) h represents error; the subscript h (water) indicates horizontal error, the subscript h (vertical) indicates vertical error, the subscript h (bend) indicates bending error, the subscript h (water assembly) indicates horizontal assembly error, and the subscript h (vertical assembly) indicates vertical assembly error; the superscript h (arrow) indicates a vector. 0nmin It is a 0n The minimum value within a sequence; Laser rangefinder in b n The system compensation value for horizontal distance measurement is h. 水装 =h 90水装 =Δa 90n -1 / 2 (Δa) 0n +Δa 180n The horizontal ranging system is compensated point by point based on the measurement pitch.

3. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, The laser rangefinder is mounted on a slider, which is mounted on a linear guide rail. The slider is also mounted on an adapter, which is mounted on a lead screw nut. The lead screw nut is mounted on a lead screw parallel to the linear guide rail. The lead screw is connected to a servo motor. The position of the laser rangefinder on the linear guide rail is controlled by controlling the left and right rotation of the servo motor. The linear guide rail is mounted on a long shaft component.

4. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, The long shaft part is mounted in bearings at both ends, and the bearings are mounted on the bed.

5. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, The method for obtaining the measurement pitch is as follows: With the long shaft part at 0°, the laser rangefinder emits a linear laser beam horizontally, creating a diffuse reflection on the long shaft part as a bright line segment. The highest point of the part being measured is placed within the scanning range of this bright line segment. The distance values ​​from the laser rangefinder to several points within the bright line segment are detected, and the minimum value among these distance values ​​is obtained as the measurement pitch. This method is repeated to obtain (a... n b n All measured pitches.

6. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, The water tank is first allowed to stand still to eliminate ripples on the reflective surface, and the water tank and the liquid or liquid film inside the water tank do not move during the entire measurement process.

7. The error compensation method for a large-span laser horizontal ranging system according to claim 1, characterized in that, Single-sided measurement compensation is performed based on system error: The long axis part is rotated to 0°, and the laser rangefinder emits a linear laser in the horizontal direction; the laser forms diffuse reflection on the long axis part, appearing as a bright line segment; the high point of the part being measured is placed within the scanning range of the bright line segment, and the distance values ​​from several points within the bright line segment to the laser rangefinder are detected, thus obtaining the minimum value among these distance values, denoted as a1; simultaneously, based on the rotation speed of the servo motor, the position b1 of the laser rangefinder is calculated; the position of the laser rangefinder on the long axis part of the crossbeam is adjusted, and the above ranging action is repeated to obtain (a2, b2) to (a max b max );(a max b max (a) represents the measured data. n +Δa 90n -1 / 2 (Δa) 0n +Δa 180n b) n Calculate the straightness of the long shaft part; where Δa 0n It is b 0n The systematic error in the direction of gravity at that location.

8. The error compensation method for a large-span laser horizontal ranging system according to claim 7, characterized in that, Three-dimensional measurement compensation based on system error: Rotate the long shaft part by a certain angle and repeat step S5 to obtain the straightness of the long shaft part at multiple angles.

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