CN107860309B - Method and device for improving measurement precision of laser tracker - Google Patents
Method and device for improving measurement precision of laser tracker Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B21/00—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
- G01B21/02—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
- G01B21/04—Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness by measuring coordinates of points
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Abstract
A method and a device for improving the measurement precision of a laser tracker comprise the following steps: calibrating the laser tracker based on the length standard device to obtain the observed quantity of the calibration point; establishing a function model and a random model of the observed quantity of the calibration point, and calculating and obtaining the correction of the observed quantity of the calibration point and the precision of the tolerance value of the observed quantity; and correcting the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the allowance value of the observed quantity, and obtaining the correction of the observed quantity of the target point and the observed quantity after the correction of the target point. And calibrating the laser tracker based on the length standard device, and correcting errors of observed quantity of the target point actually measured by the laser tracker by using the observed quantity of the calibrated point obtained by calibration, thereby improving the measurement accuracy of the laser tracker.
Description
Technical Field
The application relates to the technical field of laser measurement, in particular to a method and a device for improving the measurement precision of a laser tracker.
Background
The laser tracker is a high-precision large-size measuring instrument in an industrial measuring system, and has the characteristics of high precision, high efficiency, real-time measurement and the like. The measuring principle is that the coordinates of the sphere center of the reflecting sphere are calculated by obtaining the horizontal angle, the vertical angle and the side length from the instrument center to the sphere center of the reflecting sphere.
The factors influencing the measurement precision of the laser tracker are mainly angle measurement errors and ranging errors, and the errors are mainly caused by incorrect geometric positions of internal components of the laser tracker, and although the angle measurement errors and the ranging errors can be compensated by establishing an instrument geometric error model, the geometric error model has more parameters and relevance, so that the current precision level of the laser tracker is not high.
Along with the increasing requirements of precision in workpiece manufacturing and assembly in the fields of aerospace, shipbuilding, nuclear energy, rail transit, large scientific devices and the like in China, the higher requirements are correspondingly provided for the measuring precision of instruments.
Disclosure of Invention
The application provides a method and a device for improving the measurement precision of a laser tracker, so as to improve the measurement precision of the laser tracker.
A method for improving measurement accuracy of a laser tracker, comprising: calibrating the laser tracker based on the length standard device to obtain the observed quantity of the calibration point and calculating to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity tolerance value; interpolation correction is carried out on the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point, so that the correction of the observed quantity of the target point is obtained; and adding the observed quantity of the target point and the correction of the observed quantity of the target point to obtain the corrected observed quantity of the target point.
Preferably, the calculation method for the correction of the observed quantity of the calibration point and the precision of the observed quantity tolerance value is as follows: and establishing a function model and a random model of the observed quantity of the calibration point, combining the function model and the random model, obtaining a correction equation of the observed quantity and a variance array of the observed quantity allowance according to a least square principle, substituting the observed quantity of the calibration point into the correction equation of the observed quantity and the variance array of the observed quantity allowance to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity allowance of the calibration point respectively.
Preferably, the function model and the random model are combined, and the posterior square difference array of the observed quantity is obtained according to the least square principle.
Preferably, the function model for establishing the observed quantity of the calibration point comprises establishing a laser tracker instrument coordinate system, a global coordinate system and a laser interferometer coordinate system; and introducing an azimuth angle W to convert an instrument coordinate system of the laser tracker and a global coordinate system, and introducing a rotation angle R to convert the global coordinate system and the laser interferometer coordinate system.
Preferably, the interpolation correction calculation method of the target point observed quantity is as follows: constructing a sphere by taking the origin of a laser tracker instrument coordinate system as the sphere center, mapping a standard point and a target point on the surface of the sphere, interpolating the horizontal direction observed quantity of the target point, selecting the standard points which are adjacent around the standard point and have higher precision than the prior precision of the horizontal direction observed quantity of the target point, and performing interpolation calculation to obtain the correction of the horizontal direction observed quantity of the target point; and similarly, interpolating the observed quantity of the zenith distance of the target point to obtain the correction of the observed quantity of the zenith distance of the target point.
Preferably, the method for obtaining the observed quantity of the target point is as follows: the method comprises the steps that a laser interferometer of a length standard device is fixed on the length standard device, a laser tracker is firmly erected, a moving platform of the length standard device moves on a guide rail of the length standard device, a plurality of stay points are selected on a moving path to serve as standard points, the laser interferometer measures the standard points to obtain length observables, and the laser tracker measures the standard points to obtain horizontal observables, zenith distance observables and side length observables; changing the erection direction and/or position of the laser tracker, repeating the above measurement steps to ensure that the horizontal direction observation quantity of the laser tracker covers the range of 0-360 degrees, the zenith distance observation quantity covers the range of 0-180 degrees and the side length observation quantity covers the measurement radius of the laser tracker.
Preferably, the method for measuring the calibration point by the laser tracker comprises the following steps: the horizontal measurement calibration, the length standard device is horizontally placed, the laser tracker is at least 2m far away from the length standard device, the laser tracker is firmly erected at the middle position of the length standard device, and the laser tracker measures the calibration point to obtain the observed quantity of the calibration point; the vertical measurement calibration, the length standard device is vertically placed, the laser tracker is at least 2m far away from the length standard device, the laser tracker is firmly erected at the middle position of the length standard device, and the laser tracker measures the calibration point to obtain the observed quantity of the calibration point; and (3) longitudinal measurement calibration, wherein the length standard device is horizontally arranged, the laser tracker is firmly arranged at the end head of the length standard device, and the laser tracker measures the calibration point to obtain the observed quantity of the calibration point.
Preferably, the method for measuring the calibration point by the laser tracker further comprises the following steps of: the length standard device and the ground are obliquely placed at an included angle of 45 degrees, the laser tracker is at least 2m away from the length standard device, and the laser tracker is firmly erected at the middle position of the length standard device; the laser tracker measures the calibration point to obtain the observed quantity of the calibration point.
A device for improving the measurement precision of a laser tracker comprises a length standard device and the laser tracker; the laser interferometer of the length standard device is fixed on the length standard device, and the laser tracker is stably erected; the method comprises the steps that a moving platform moves on a guide rail of a length standard device, a plurality of stay points are selected on a moving path to serve as standard points, a laser interferometer measures the standard points to obtain length observables, and a laser tracker measures the standard points to obtain horizontal observables, zenith distance observables and side length observables; changing the erection direction and/or position of the laser tracker, repeating the measurement steps to ensure that the horizontal direction observed quantity of the laser tracker covers the range of 0-360 degrees, the zenith distance observed quantity covers the range of 0-180 degrees and the side length observed quantity covers the measurement radius of the laser tracker; correcting the observed quantity of the target point according to the observed quantity of the target point and the calculated correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point to obtain the correction of the observed quantity of the target point, and adding the observed quantity of the target point and the correction of the observed quantity of the target point to obtain the observed quantity after the correction of the target point.
Preferably, the calculation process for obtaining the observed quantity correction of the target point is as follows: establishing a function model and a random model of the observed quantity of the calibration point, combining the function model and the random model, obtaining a correction equation of the observed quantity and a variance array of the observed quantity allowance according to a least square principle, substituting the observed quantity of the calibration point into the correction equation of the observed quantity and the variance array of the observed quantity allowance to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity allowance of the calibration point respectively; and carrying out interpolation correction on the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point, and obtaining the correction of the observed quantity of the target point.
Preferably, the calculation process of interpolation correction of observed quantity of the target point is as follows: constructing a sphere by taking the origin of a laser tracker instrument coordinate system as the sphere center, mapping a standard point and a target point on the surface of the sphere, interpolating the horizontal direction observed quantity of the target point, selecting the standard points which are adjacent around the standard point and have higher precision than the prior precision of the horizontal direction observed quantity of the target point, and performing interpolation calculation to obtain the correction of the horizontal direction observed quantity of the target point; and similarly, interpolating the observed quantity of the zenith distance of the target point to obtain the correction of the observed quantity of the zenith distance of the target point.
According to the technical scheme, the laser tracker is calibrated based on the length standard device, and then the observed quantity of the calibrated point obtained by calibration is used for carrying out error correction on the observed quantity of the target point actually measured by the laser tracker, so that the measurement precision of the laser tracker is improved. According to the invention, the conversion of the instrument coordinate system of the laser tracker and the global coordinate system is carried out by introducing the azimuth angle W, the conversion of the global coordinate system and the laser interferometer coordinate system is carried out by introducing the rotation angle R, and the mathematical relationship between the observed quantity of the laser tracker to the calibration point and the observed quantity of the laser interferometer to the calibration point is established, so that the influence of cosine errors caused by the non-parallelism of the motion axis of the reflecting mirror of the laser tracker and the laser beam direction of the laser interferometer is thoroughly eliminated, the requirements on the guide rail straightness of the length standard device and the light beam adjustment precision of the laser interferometer are reduced, the construction standard of the length standard device is reduced, the trend of the length standard device is civilian, and the instrument and the precision compensation can be carried out in a common unit.
Meanwhile, on the basis of providing an indication error for instrument calibration, the invention can intuitively calculate the measurement errors of the instrument in the horizontal direction, the zenith distance and the side length through the post-inspection square difference array of observed quantity, which has important significance for performance evaluation of the instrument.
Drawings
FIG. 1 is a schematic illustration of the placement of a length standard device and a laser tracker mirror of the present invention;
fig. 2 is a flowchart of a first embodiment of the present invention. Fig. 3 is a coordinate system of the laser tracker apparatus of the present invention.
Detailed Description
The invention will be described in further detail below with reference to the drawings by means of specific embodiments.
The basic idea of the invention is that aiming at the characteristic of high measurement repeatability of the laser tracker, the invention provides a length-based standard device for calibrating the observed quantity of the laser tracker, and then the observed quantity of the calibrated point obtained by calibration is used for carrying out error correction on the observed quantity of the target point actually measured by the laser tracker, thereby improving the measurement precision of the laser tracker.
In order to make the technical personnel better understand the scheme of the invention, the length standard device applied in the invention is firstly described below, and the length standard device mainly comprises four parts of a precise guide rail system, a length laser measuring system, an environment monitoring system and an automatic control system. The precise guide rail system is a linear guide rail; the length laser measurement system uses a laser interferometer as a measurement reference; the environment monitoring system is used for collecting parameters such as temperature and the like and compensating the parameters in real time. The working method of the length standard device comprises the following steps: the pyramid reflector of the laser interferometer is placed on a moving platform, the moving platform is driven by a motor to run along a linear guide rail, and the moving distance is measured by a laser interference system. The standard device with the length of 80m is provided in China measuring institute, and all standard devices with the length of 30m are researched in Beijing great wall measuring test technology in China aviation industry.
Embodiment one: referring to fig. 2, the method for improving the measurement accuracy of the laser tracker specifically includes the following steps:
and 101, calibrating a laser tracker based on a length standard device to obtain observed quantity (alpha, beta, S, L) of a calibration point P and calculating to obtain the correction of the observed quantity of the calibration point and the precision of an observed quantity tolerance value, wherein alpha is the horizontal direction observed quantity of the laser tracker to the calibration point, beta is the zenith distance observed quantity of the laser tracker to the calibration point, S is the side length observed quantity of the laser tracker to the calibration point, and L is the length observed quantity of the laser interferometer to the calibration point.
The method for obtaining the observed quantity of the standard point P comprises the following steps: fixing a reflecting mirror of a laser interferometer of the length standard device and a reflecting mirror of a laser tracker on a motion platform of the length standard device, fixing the laser interferometer of the length standard device on the length standard device, and then respectively performing horizontal measurement and calibration:
1) The length standard device is horizontally placed; the laser tracker is at least 2m away from the length standard device, and is firmly arranged at the middle position of the length standard device. 2) The motion platform of the length standard device moves on the guide rail of the length standard device, a standard point is taken every time the motion platform moves for a certain distance, the laser interferometer and the laser tracker respectively measure, and the observed quantity of the standard point is recorded. 3) After the measurement is completed, the laser tracker is horizontally rotated for a certain angle and then is firmly erected again, and the measurement is performed according to the step 2, so that the coverage of the measurement range of the horizontal direction observed quantity of the laser tracker by 0-360 degrees is ensured. 4) And (3) stably erecting the laser tracker again after ascending or descending by one height so as to ensure that the measuring range of the zenith distance observed quantity during the measurement of the laser tracker covers the range of 0-180 degrees, and repeating the steps 2-3 to finish the calibration of the horizontal direction observed quantity. The laser tracker is stably erected in the middle of the length standard device, namely the laser tracker is positioned on the middle plane of the length standard device and has the same height as the middle point of the guide rail, and the same lower height.
And (3) vertical measurement calibration: 1) The length standard device is vertically placed; the laser tracker is at least 2m away from the length standard device, and is firmly arranged at the middle position of the length standard device. 2) The motion platform of the length standard device moves on the guide rail of the length standard device, a standard point is taken every time the motion platform moves for a certain distance, the laser interferometer and the laser tracker respectively measure, and the observed quantity of the standard point is recorded. 3) After the measurement is completed, the laser tracker is stably erected again after being lifted or lowered by one height, and the measurement is performed according to the step 2, so that the measurement range of the zenith distance observed quantity during the measurement of the laser tracker is ensured to cover 0-180 degrees. 4) And (3) horizontally rotating the laser tracker by a certain angle, then stably erecting again to ensure that the measurement range of the horizontal direction observed quantity of the laser tracker covers 0-360 degrees, and repeating the step (2-3) to finish the calibration of the zenith distance observed quantity.
And (3) longitudinal measurement and calibration: 1) The length standard device is horizontally arranged, and the laser tracker is firmly arranged at the end head of the length standard device and is equal to the guide rail in height. 2) The motion platform of the length standard device moves on the guide rail of the length standard device, a standard point is taken every time the motion platform moves for a certain distance, the laser interferometer and the laser tracker respectively measure, and the observed quantity of the standard point is recorded. 3) After the measurement is completed, the laser tracker is stably erected again after moving forwards or backwards for a certain distance, and the measurement is performed according to the step 2, so that the measurement range of the side length observed quantity during the measurement of the laser tracker is ensured to cover the measurement radius of the laser tracker. 4) And (3) repeating the step (2-3) to finish the calibration of the side length observed quantity.
Diagonal measurement calibration: 1) The length standard device and the ground are obliquely placed at an included angle of 45 degrees, the laser tracker is at least 2m away from the length standard device, and the laser tracker is firmly erected at the middle position of the length standard device. The laser tracker performs left diagonal measurement calibration when placed on the left side of the length standard device, and performs right diagonal measurement calibration when placed on the right side of the length standard device. 2) The motion platform of the length standard device moves on the guide rail of the length standard device, a standard point is taken every time the motion platform moves for a certain distance, the laser interferometer and the laser tracker respectively measure, and the observed quantity of the standard point is recorded. 3) After the measurement is completed, the laser tracker is horizontally rotated for a certain angle and then is firmly erected again, and the measurement is performed according to the step 2, so that the coverage of the measurement range of the horizontal direction observed quantity of the laser tracker by 0-360 degrees is ensured. 4) And (3) stably erecting the laser tracker again after ascending or descending by one height so as to ensure that the measuring range of the zenith distance observed quantity during the measurement of the laser tracker covers the range of 0-180 degrees, repeating the steps (2-3), and supplementing the calibration of the horizontal direction observed quantity and the zenith distance observed quantity.
The precision method for obtaining the correction of the observed quantity of the standard point and the tolerance value of the observed quantity is as follows:
establishing a laser tracker instrument coordinate system, a global coordinate system and a laser interferometer coordinate system;
referring to fig. 3, the laser tracker instrument coordinate system: the central point of the laser tracker is taken as an original point, the vertical axis is taken as a first axis Z axis, the zero direction of the laser tracker is taken as a second axis X axis, the zero direction of the laser tracker refers to the direction of zero observed value in the horizontal direction, and the zero direction is generally and specifically pointed to the base point of the laser tracker. The three-dimensional coordinates of the object in the instrument coordinate system are (X T ,Y T ,Z T ) See formula (1);
global coordinate system: taking the instrument center point of the laser tracker as an origin, taking a vertical axis as a first axis Z axis, taking the laser beam direction of the laser interferometer as a second axis X axis, and taking the three-dimensional coordinates of a target under a global coordinate system as (X, Y, Z), as shown in a formula (2), wherein W is the azimuth angle of the zero direction of the laser tracker under the global coordinate system;
laser interferometer coordinate system: taking a distance measurement zero point of the laser interferometer as an origin and a laser beam direction of the laser interferometer as a first axis X axis, the conversion relation between a laser interferometer coordinate system and a global coordinate system is shown in formula (3), wherein R is a rotation angle for converting the laser interferometer coordinate system and the global coordinate system, and a three-dimensional coordinate of a target under the laser interferometer coordinate system is (X I ,Y I ,Z I )；
For the horizontal direction observation quantity of the calibration point under the laser tracker, there is an observation equationThe adjustment equation is:wherein the method comprises the steps of
Order theThe error equation in the horizontal direction is:
for the zenith distance observed quantity of a calibration point under a laser tracker, an observation equation is providedThe adjustment equation is: />Wherein the method comprises the steps of
Order theThe error equation for the zenith distance is:
for the side length observation quantity of the calibration point under the laser tracker, the observation equation is thatThe adjustment equation is: />
Order theThe error equation for the side length is:
for the length observation quantity of the standard point under the laser interferometer, through the formula (3), the observation equation is thatThe adjustment equation is:
order theThe error equation for the length is:
assuming that the laser tracker measures n calibration points, a matrix form of error equations can be obtained according to equations (4) - (7):
wherein:
establishing a random model to obtain observed quantity and mutual statistical correlation property: observed quantity alpha in function model (8) i 、β i 、S i 、L i Is a random quantity, parameters in the modelNon-random quantity, obtaining a random model, namely a variance matrix of observed quantity:wherein Q is a observed quantity co-factor matrix, P is an observed quantity weight matrix,>is unit weight variance +.>Can be any constant selected, P and Q are inverse arrays, and observables are independent, so that the weight array P is a diagonal array and sigma αi 、σ βi 、σ Si 、σ Li Is the prior precision of the observed quantity.
The formula is shown as follows;
since the laser tracker measures n calibration points, there are a total of 4n observation equations with 3n+3 unknown parameters, the number of observation equations should be not less than the number of unknown parameters, i.e., n.gtoreq.3, according to the least squares principle, in the above formula (8)Must satisfy V T Pv=min, then get:
substituting equation (9) into equation (8) yields the correction equation:
V＝B(B T PB) -1 B T Pl-l (10)
unit weight varianceEstimate of +.>The method comprises the following steps:
post-inspection square difference matrix of observed quantity:
variance matrix of observed quantity variance values:
substituting the observed quantity of the calibration point P (alpha, beta, S, L) into formulas (10) and (12) to obtain the calibration point P i Correction v αi 、v βi 、v Si Accuracy of difference value between sum and observed quantity
And 102, carrying out interpolation correction on the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point to obtain the correction of the observed quantity of the target point.
The interpolation correction method is as follows:
because the laser tracker has high ranging precision, the precision is mainly limited by the precision of the measured angle, so the angle of the laser tracker is mainly corrected. Taking the origin of a laser tracker instrument coordinate system as a sphere center, constructing a sphere, mapping a standard point and a target point on the surface of the sphere, interpolating the horizontal direction observed quantity of the target point M, and selecting 4 adjacent standard points P with the precision of the tolerance value of the horizontal direction observed quantity higher than the prior precision around the standard point P i 、P j 、P k 、P l Interpolation calculation is carried out to obtain the observed quantity alpha of the horizontal direction of the target point M m The correction of (2):
(13) The method comprises the steps of carrying out a first treatment on the surface of the The prior precision refers to the standard precision of the instrument given by an instrument manufacturer.
Similarly, the zenith distance observed quantity beta of the target point M is obtained by interpolation of the zenith distance observed quantity of the target point M m The correction v of (2) βm 。
Also, in other embodiments of the present invention, it is not limited to selecting only 4 calibration points adjacent to the periphery of the target point, but 1, 2, 6, 8 or even 12 calibration points may be selected, and interpolation calculation is preferably performed on the calibration points in which the adjustment accuracy is 2 times higher than the prior accuracy, so as to obtain a more accurate correction.
And 103, adding the observed quantity of the target point and the correction of the observed quantity of the target point to obtain the observed quantity after the correction of the target point.
Referring to fig. 1, the device for improving the measurement precision of a laser tracker of the present invention comprises a length standard device 1 and the laser tracker; the method comprises the steps that a laser interferometer reflector 11 of a length standard device and a laser tracker reflector 2 of the laser tracker are fixed on a moving platform 12 of the length standard device, a laser interferometer 13 of the length standard device is fixed at one end of a guide rail 14 of the length standard device, the laser tracker is firmly erected, the moving platform 12 of the length standard device moves on the guide rail 14 of the length standard device, a plurality of stay points are selected on a moving path to serve as standard points, the laser interferometer 13 measures the standard points to obtain a length observed quantity L, and the laser tracker measures the standard points to obtain a horizontal direction observed quantity alpha, a zenith distance observed quantity beta and a side length observed quantity S; after the laser tracker finishes measuring all the current calibration points on one measuring station, changing the erection direction and/or position of the laser tracker to enable the moving platform 12 to move on the guide rail 14 of the length standard device, selecting a plurality of stay points on a moving path as calibration points, and measuring the calibration points on a new measuring station; repeating the measuring steps to ensure that the observed quantity alpha in the horizontal direction of the laser tracker covers the range of 0-360 degrees, the observed quantity beta in the zenith distance covers the range of 0-180 degrees, and the observed quantity S in the side length covers the measuring radius of the laser tracker, so as to obtain the observed quantity of the standard point.
After obtaining the observed quantity of the target point, the observed quantity after the correction of the target point is obtained according to the calculation method in the first embodiment.
The foregoing description of the invention has been presented for purposes of illustration and description, and is not intended to be limiting. Several simple deductions, modifications or substitutions may also be made by a person skilled in the art to which the invention pertains, based on the idea of the invention.
Claims (9)
1. A method for improving the measurement accuracy of a laser tracker, comprising the steps of:
calibrating the laser tracker based on the length standard device to obtain the observed quantity of the calibration point and calculating to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity tolerance value;
interpolation correction is carried out on the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point, so that the correction of the observed quantity of the target point is obtained;
adding the observed quantity of the target point and the correction of the observed quantity of the target point to obtain the corrected observed quantity of the target point so as to improve the measurement precision of the laser tracker;
the interpolation correction calculation method of the target point observed quantity comprises the following steps: taking the origin of a laser tracker instrument coordinate system as a sphere center, constructing a sphere, mapping a standard point and a target point on the surface of the sphere, interpolating the horizontal direction observed quantity of the target point, and selecting 4 adjacent standard points P with higher precision than the prior precision of the tolerance value of the horizontal direction observed quantity around the standard point P i 、P j 、P k 、P l Interpolation calculation is carried out to obtain the observed quantity alpha of the horizontal direction of the target point m The correction of (2):
wherein the v αi 、v αj 、v αk And v αl Respectively, marked point P i 、P j 、P k 、P l The correction of (a), theAnd->The precision of the difference value of the corresponding observed quantity, the alpha i 、α j 、α k And alpha l Respectively the laser tracker pair calibration points P i 、P j 、P k 、P l Is a horizontal direction observation amount of (2);
and similarly, interpolating the observed quantity of the zenith distance of the target point to obtain the correction of the observed quantity of the zenith distance of the target point.
2. The method for improving the measurement accuracy of a laser tracker according to claim 1, wherein the calculation method for the correction of the observed quantity of the calibration point and the accuracy of the observed quantity tolerance value is as follows:
and establishing a function model and a random model of the observed quantity of the calibration point, combining the function model and the random model, obtaining a correction equation of the observed quantity and a variance array of the observed quantity allowance according to a least square principle, substituting the observed quantity of the calibration point into the correction equation of the observed quantity and the variance array of the observed quantity allowance to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity allowance of the calibration point respectively.
3. The method for improving the measurement accuracy of the laser tracker according to claim 2, wherein the function model and the random model are combined, and the posterior square difference array of the observed quantity is obtained according to the least square principle.
4. The method for improving the measurement accuracy of the laser tracker according to claim 2, wherein the establishing a function model of the observed quantity of the calibration points comprises establishing a laser tracker instrument coordinate system, a global coordinate system and a laser interferometer coordinate system; and introducing an azimuth angle W to convert an instrument coordinate system of the laser tracker and a global coordinate system, and introducing a rotation angle R to convert the global coordinate system and the laser interferometer coordinate system.
5. The method for improving the measurement accuracy of a laser tracker according to any one of claims 1 to 4, wherein the method for obtaining the observed quantity of the calibration point is as follows:
the method comprises the steps that a laser interferometer of a length standard device is fixed on the length standard device, a laser tracker is firmly erected, a laser interferometer reflector of the length standard device and a laser tracker reflector are fixed on a moving platform of the length standard device, the moving platform of the length standard device moves on a guide rail of the length standard device, a plurality of stay points are selected on a moving path to serve as standard points, the laser interferometer measures the standard points to obtain length observables, and the laser tracker measures the standard points to obtain horizontal direction observables, zenith distance observables and side length observables; changing the erection direction and/or position of the laser tracker, repeating the above measurement steps to ensure that the horizontal direction observation quantity of the laser tracker covers the range of 0-360 degrees, the zenith distance observation quantity covers the range of 0-180 degrees and the side length observation quantity covers the measurement radius of the laser tracker.
6. The method for improving the measurement accuracy of a laser tracker according to claim 5, wherein the method for measuring the calibration point by the laser tracker is as follows:
and (3) horizontal measurement and calibration: the length standard device is horizontally arranged, the laser tracker is at least 2m away from the length standard device, and the laser tracker is firmly erected at the middle position of the length standard device; the laser tracker measures the calibration point to obtain the observed quantity of the calibration point;
and (3) vertical measurement calibration: the length standard device is vertically arranged, the laser tracker is at least 2m away from the length standard device, and the laser tracker is firmly erected at the middle position of the length standard device; the laser tracker measures the calibration point to obtain the observed quantity of the calibration point;
and (3) longitudinal measurement and calibration: the length standard device is horizontally arranged, and the laser tracker is firmly erected at the end of the length standard device; the laser tracker measures the calibration point to obtain the observed quantity of the calibration point;
diagonal measurement calibration: the length standard device and the ground are obliquely placed at an included angle of 45 degrees, the laser tracker is at least 2m away from the length standard device, and the laser tracker is firmly erected at the middle position of the length standard device; the laser tracker measures the calibration point to obtain the observed quantity of the calibration point.
7. The device for improving the measurement precision of the laser tracker is characterized by comprising a length standard device and the laser tracker; the laser interferometer of the length standard device is fixed on the length standard device, and the laser tracker is stably erected; the method comprises the steps that a moving platform moves on a guide rail of a length standard device, a plurality of stay points are selected on a moving path to serve as standard points, a laser interferometer measures the standard points to obtain length observables, and a laser tracker measures the standard points to obtain horizontal observables, zenith distance observables and side length observables; changing the erection direction and/or position of the laser tracker, repeating the measurement steps to ensure that the horizontal direction observed quantity of the laser tracker covers the range of 0-360 degrees, the zenith distance observed quantity covers the range of 0-180 degrees and the side length observed quantity covers the measurement radius of the laser tracker; correcting the observed quantity of the target point according to the observed quantity of the target point and the calculated correction of the observed quantity of the target point and the calculated precision of the deviation value of the observed quantity of the target point to obtain the correction of the observed quantity of the target point, and adding the observed quantity of the target point and the correction of the observed quantity of the target point to obtain the observed quantity after the correction of the target point.
8. The apparatus for improving the measurement accuracy of a laser tracker according to claim 7, wherein the calculation process for obtaining the observed quantity correction of the target point is:
establishing a function model and a random model of the observed quantity of the calibration point, combining the function model and the random model, obtaining a correction equation of the observed quantity and a variance array of the observed quantity allowance according to a least square principle, substituting the observed quantity of the calibration point into the correction equation of the observed quantity and the variance array of the observed quantity allowance to obtain the correction of the observed quantity of the calibration point and the precision of the observed quantity allowance of the calibration point respectively; and carrying out interpolation correction on the observed quantity of the target point according to the observed quantity of the target point, the correction of the observed quantity of the target point and the precision of the deviation value of the observed quantity of the target point, and obtaining the correction of the observed quantity of the target point.
9. The apparatus for improving the measurement accuracy of a laser tracker according to claim 8, wherein the calculation process of interpolation correction of observed quantity of the target point is:
constructing a sphere by taking the origin of a laser tracker instrument coordinate system as the sphere center, mapping a standard point and a target point on the surface of the sphere, interpolating the horizontal direction observed quantity of the target point, selecting the standard points which are adjacent around the standard point and have higher precision than the prior precision of the horizontal direction observed quantity of the target point, and performing interpolation calculation to obtain the correction of the horizontal direction observed quantity of the target point;
and similarly, interpolating the observed quantity of the zenith distance of the target point to obtain the correction of the observed quantity of the zenith distance of the target point.
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