CN107290734B - Point cloud error correction method based on self-made foundation laser radar perpendicularity error - Google Patents

Point cloud error correction method based on self-made foundation laser radar perpendicularity error Download PDF

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CN107290734B
CN107290734B CN201710724089.XA CN201710724089A CN107290734B CN 107290734 B CN107290734 B CN 107290734B CN 201710724089 A CN201710724089 A CN 201710724089A CN 107290734 B CN107290734 B CN 107290734B
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CN107290734A (en
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李小路
徐立军
李昀晔
谢鑫浩
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Beihang University
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Abstract

The invention discloses a point cloud error correction method based on self-made foundation laser radar perpendicularity errors, which mainly aims at a scanning mode that a self-made laser radar system 45-degree rotating mirror is matched with a holder to rotate, establishes a self-made laser radar system point cloud error correction model by calculating the influence of the perpendicularity errors of a pitch axis and an azimuth axis on angle measurement errors of the self-made system, and solves the perpendicularity errors by using a high-precision three-dimensional scanner to use scanning point cloud coordinates of a target as a true value, so that the error correction of the self-made laser radar system perpendicularity errors on target point clouds is realized. The method mainly comprises the following three steps: 1) establishing a self-made laser radar three-dimensional imaging system angle measurement error model caused by perpendicularity errors and simplifying the model; 2) obtaining a point cloud error model of a self-made laser radar three-dimensional imaging system; 3) and solving the perpendicularity error in the point cloud error model of the self-made laser radar three-dimensional imaging system, and correcting the target point cloud of the self-made laser radar system according to the model.

Description

Point cloud error correction method based on self-made foundation laser radar perpendicularity error
Technical Field
The invention relates to the technical field of laser radar measurement, in particular to a point cloud error correction method based on self-made foundation laser radar perpendicularity error
Background
The laser radar measurement technology is a new active remote sensing technology which is rapidly developed in recent years, generally adopts a non-contact measurement technology, and has wide application in the fields of remote sensing, military exploration, ocean mapping and atmospheric exploration. The three-dimensional scanning measurement technology in the laser radar can quickly acquire high-resolution point cloud data of the surface of a target object in a high-speed laser scanning mode on the basis of the traditional single-point measurement technology, and has the advantages of simplicity in data processing, rapidity, initiative, strong anti-interference capability, high measurement precision, large range and the like. However, the scanning accuracy of the laser radar is greatly affected by the accuracy of the laser radar, and in actual use, the accuracy of the laser radar does not completely meet the nominal accuracy of the laser radar, or the performance of the laser radar is unstable due to external force collision, external condition change, loss caused by long-time use and other unknown factors, and systematic errors may occur in a scanning result. Therefore, the method effectively eliminates the error of the laser radar instrument and is the key for improving the accuracy of the scanning point cloud.
According to the existing research results, laser radars are mainly divided into two categories, namely an airborne laser radar and a ground laser radar, point cloud error correction methods related to a laser radar three-dimensional imaging system are different, the first category of calibration method based on the airborne laser radar system is mainly based on flight self-calibration, and the basic idea is that laser is used for scanning known target points or relative target points and carrying out parameter estimation on fixed offset generated in the process, wherein the parameter estimation comprises an overlapped flight zone calibration technology, a least square balance method geometric calibration technology and the like. The overlapped flight band calibration technology has higher requirements on the flight band splicing technology; the assumption precondition in the adjustment method is generally difficult to be satisfied, and the problems of parameter estimation accuracy reduction and the like can be caused. The calibration method of the airborne laser radar system has no contrast with the method and reference.
The second type of calibration method based on the ground laser radar system is mostly completed in an indoor or baseline field, some verification experiments related to point location precision mainly adopt a common point conversion method, and most target matched with the system is adopted for testing, including a space length detection method, a self-checking method and the like. The space length detection method has higher requirements on a detection field, requires the field to have high precision, and depends on the precision of the layout of the scanning targets; the self-calibration method generally adopts instruments such as a total station instrument, a theodolite and the like to establish a calibration model for the laser radar system, the model generally comprises parameters such as a coordinate system rotation angle, a translation amount, an instrument internal error and the like, the parameters are used as unknown quantities and are solved uniformly, the method can continuously perfect the error model by increasing the parameters, the correction precision of the system error is improved, the range of the calibration laser radar system is wider, and the calibration laser radar system has no very high requirement on the arrangement precision of target objects. The invention belongs to a system self-checking method.
According to patent review provided by the prior patent office, the self-calibration method of the ground laser radar system is mainly divided into the following two types: the first method adopts a common mark point to obtain the coordinate rotation and translation amount between the system to be calibrated and the high-precision scanner, and directly takes the difference between the measured value of the system to be calibrated and the standard measured value as the measurement error of the system space coordinate. The method aims at all space three-dimensional coordinate measuring systems to obtain space coordinate measuring relative errors, and has the defects that the errors are evaluated and corrected only on a three-dimensional point cloud layer, a system error model is not constructed, and accurate correction can be realized only by a large amount of sample data; the above patent includes "a calibration method of an electronic theodolite space coordinate measurement system" disclosed in chinese patent 200810147441.9. The second method adopts a statistical method to analyze the probability density distribution of the system ranging error and the angle measurement error to obtain an error correction sample in a three-dimensional coordinate system. The method aims at all three-dimensional coordinate measurement systems to obtain a system error correction model, and has the defects that system error model parameters have no physical significance, and theoretical analysis is not carried out from the angle of an error source according to the scanning mode of the system, so that accurate correction can be realized only by depending on large sample data; the above patent includes "a method for correcting a measurement error of a long-distance scanning laser radar" disclosed in chinese patent 201710014687.8.
The main difference between the invention and the prior system self-checking method is that: the method is suitable for all three-dimensional scanning systems adopting a 45-degree rotating mirror matched pan-tilt rotating scanning mode. The invention has wide application prospect in the technical field of laser radar measurement.
Disclosure of Invention
The invention discloses a point cloud error correction method based on self-made foundation laser radar perpendicularity error, which is characterized in that the method aims at a scanning mode that a 45-degree rotating mirror in a self-made laser radar three-dimensional imaging system is matched with a holder to rotate, wherein the self-made laser radar three-dimensional imaging system comprises an optical system, a scanning mechanism (a motor, the 45-degree rotating mirror) and the holder; incident light is emitted to the center (O point) of the 45-degree rotating mirror through the optical system, and the self-made laser radar three-dimensional laser radar is driven to rotate horizontally by the cradle head along with the vertical rotation of the scanning mechanismEmitting in an imaging system; the ideal coordinate system (O-XYZ) of the self-made laser radar three-dimensional imaging system comprises a pitch axis (X axis), an initial emergent ray direction (Y axis) and an azimuth axis (Z axis); on the basis of the ideal coordinate system (O-XYZ), an included angle gamma exists between an actual pitching axis (X 'axis) and an X axis, the Y axis is unchanged, and a Z' axis is established according to a right-hand coordinate rule; the perpendicularity error is defined as the angle γ between the actual pitch axis (X' axis) and the ideal pitch axis (X axis); a one-dimensional distance L of a point P on the target in the ideal coordinate system (O-XYZ) is defined as
Figure BDA0001385598950000021
Length, azimuth angle of
Figure BDA0001385598950000022
Is defined as
Figure BDA0001385598950000023
The included angle between the projection on the XOY plane and the X axis is positive in the anticlockwise direction from the positive half shaft of the X axis and ranges from 0 degree to 360 degrees, and the pitch angle is
Figure BDA0001385598950000024
Is defined as 90 DEG and
Figure BDA0001385598950000025
and the difference of the included angle between the Z axis and the Z axis, the one-dimensional distance L and the azimuth angle
Figure BDA0001385598950000026
And the pitch angle
Figure BDA0001385598950000027
The measurement errors are respectively a distance measurement error delta L and an azimuth angle error
Figure BDA0001385598950000028
And pitch angle error
Figure BDA0001385598950000029
The self-made laser radar three-dimensional imaging system angle measurement error (azimuth angle error) is analyzed through theory
Figure BDA00013855989500000210
Error in pitch angle
Figure BDA00013855989500000211
) Establishing an angle measurement error model of the self-made laser radar three-dimensional imaging system; the point cloud of the target is defined as the rectangular coordinates (x, y, z) of a point on the targetTThe point cloud error of a target is defined as the deviation (Δ x, Δ y, Δ z) of the coordinate measurement from the true value of the target point cloudTError of point cloud (Δ x, Δ y, Δ z) according to the targetTError in angle measurement from the target (azimuth error)
Figure BDA00013855989500000212
Error in pitch angle
Figure BDA00013855989500000213
) According to the error transfer principle, a point cloud error model of the self-made laser radar three-dimensional imaging system is established as follows:
Figure BDA00013855989500000214
obtaining the target point cloud coordinate after the self-made laser radar three-dimensional imaging system corrects the perpendicularity error gamma as follows:
(x+Δx,y+Δy,z+Δz)T
thereby realizing point cloud error correction of the self-made laser radar three-dimensional imaging system perpendicularity error gamma;
the method mainly comprises the following seven steps:
1) establishing an ideal coordinate system (O-XYZ) of the self-made laser radar three-dimensional imaging system, wherein the perpendicularity error exists between the actual pitch axis (X ' axis) and the azimuth axis (Z axis), namely an included angle gamma exists between the actual pitch axis (X ' axis) and the ideal pitch axis (X axis), so that the actual pitch axis (X ' axis) and the ideal pitch axis (X axis) are actually formedChanging an inter-pitching axis into an X ' axis, keeping a Y axis unchanged, establishing a Z ' axis according to a right-hand coordinate rule, and setting the Z ' axis as an actual coordinate system (O-X ' YZ ') of the self-made laser radar three-dimensional imaging system; the measurement value of any point P on the target in the ideal coordinate system (O-XYZ) is an azimuth angle
Figure BDA00013855989500000215
Pitch angle
Figure BDA00013855989500000216
The true value of any point P on the target in the ideal coordinate system (O-XYZ) is an azimuth angle
Figure BDA0001385598950000031
Pitch angle
Figure BDA0001385598950000032
The above-mentioned
Figure BDA0001385598950000033
And
Figure BDA0001385598950000034
the difference being the azimuth error
Figure BDA0001385598950000035
The above-mentioned
Figure BDA0001385598950000036
And
Figure BDA0001385598950000037
the difference being pitch angle error
Figure BDA0001385598950000038
2) Establishing a self-made laser radar three-dimensional imaging system angle measurement error model caused by the perpendicularity error gamma; the model describes the angle measurement error (azimuth error) separately
Figure BDA0001385598950000039
Error in pitch angle
Figure BDA00013855989500000310
) And said perpendicularity error gamma and the azimuth of said target
Figure BDA00013855989500000311
Pitch angle
Figure BDA00013855989500000312
The mathematical relationship between them is as follows:
Figure BDA00013855989500000313
3) and carrying out approximate transformation on the trigonometric function value of the perpendicularity error gamma, and simplifying the angle measurement error model of the self-made laser radar three-dimensional imaging system as follows:
Figure BDA00013855989500000314
4) establishing point cloud errors (delta x, delta y, delta z) of the self-made laser radar three-dimensional imaging system according to an error transfer principleTWith said distance measurement error Δ L, said angle measurement error (azimuth error)
Figure BDA00013855989500000315
Error in pitch angle
Figure BDA00013855989500000316
) The mapping relationship between the two is as follows:
Figure BDA00013855989500000317
wherein, L is a one-dimensional distance of any point on the target in an ideal coordinate system (O-XYZ) of the self-made laser radar three-dimensional imaging system, and Delta L is a measurement error of the one-dimensional distance L of any point on the target;
5) converting the angle measurement error model of the self-made laser radar three-dimensional imaging system into a rectangular coordinate system to obtain a point cloud error model of the self-made laser radar three-dimensional imaging system as follows:
Figure BDA00013855989500000318
6) scanning N targets by using the self-made laser radar three-dimensional imaging system to obtain coordinates (x) of the targets in the self-made laser radar three-dimensional imaging systemi,yi,zi)T(i ═ 1,2, …, N) as measured values; performing secondary scanning on the target by using a high-precision three-dimensional scanner to obtain the coordinate (x ') of the target in the high-precision three-dimensional scanner'i,y′i,z′i)T(i-1, 2, …, N) which is converted into the self-made laser radar three-dimensional imaging system as a true value; the difference between the measured value and the actual value is the point cloud error (delta x) of the self-made laser radar three-dimensional imaging systemi,Δyi,Δzi)T(i ═ 1,2, …, N); obtaining the one-dimensional distance L of the target from the measured value according to the mapping relation between the spherical coordinate system and the rectangular coordinate systemiAzimuth angle
Figure BDA00013855989500000319
And a pitch angle
Figure BDA00013855989500000320
Range error Δ L of the targetiAt the one-dimensional distance LiA known constant when within a certain range;
7) solving model parameters in the self-made laser radar three-dimensional imaging system point cloud error model, namely the perpendicularity error gamma, and correcting the point cloud error of the self-made laser radar three-dimensional imaging system perpendicularity error gamma; point cloud error (delta x) of the self-made laser radar three-dimensional imaging systemi,Δyi,Δzi)T(i ═ 1,2, …, N), one-dimensional distance L of the targetiAzimuth angle
Figure BDA0001385598950000041
Pitch angle
Figure BDA0001385598950000042
And a range error Δ LiSubstituting the equation into the formula (4) to obtain 3 × N nonlinear equations, and determining the perpendicularity error gamma in the self-made laser radar three-dimensional imaging system point cloud error model by solving the nonlinear equations; substituting the perpendicularity error gamma into a formula (4) to obtain the target point cloud coordinate (x, y, z) of the self-made laser radar three-dimensional imaging systemTOn the basis, the target point cloud coordinate (x + delta x, y + delta y, z + delta z) corrected by the self-made laser radar three-dimensional imaging system is obtainedT。
Establishing an ideal coordinate system (O-XYZ) of the homemade laser radar three-dimensional imaging system; the pitching axis of the self-made laser radar three-dimensional imaging system is defined as the motor rotating shaft of the 45-degree rotating mirror, and the azimuth axis is defined as the rotating shaft of the holder; ideally, the pitch axis and the azimuth axis are perpendicular to each other, and the perpendicularity error γ is 0; the center of the reflecting surface of the 45-degree rotating mirror, namely the intersection point of the incident light on the reflecting surface is a coordinate origin O; a coordinate axis which is coincident with the pitch axis and has the same positive direction as the direction of the laser incident on the 45-degree rotating mirror is defined as an X axis; defining a coordinate axis which is the same as the initial emitting direction of the laser under an ideal condition as a Y axis; and the coordinate axis is coincident with the azimuth axis, and the coordinate axis vertically upward in the positive direction is defined as a Z axis.
Establishing a self-made laser radar three-dimensional imaging system angle measurement error model caused by the perpendicularity error gamma, and simplifying the model; because the perpendicularity error gamma exists between the actual pitch axis (X 'axis) and the azimuth axis (Z axis), namely an included angle gamma exists between the actual pitch axis (X' axis) and the ideal pitch axis (X axis), the actual coordinate system O-X 'YZ' is established, and the establishing process of the angle measurement error model of the homemade laser radar three-dimensional imaging system is as follows:
the unit vector of the normal of the 45 ° rotating mirror (in the O-X 'YZ' coordinate system) is initially:
Figure BDA0001385598950000043
ideally, the outgoing ray passes through a point P on the target, where the normal vector of the 45 ° turning mirror (in the O-XYZ coordinate system) is:
Figure BDA0001385598950000044
in the formula (6)
Figure BDA0001385598950000045
The pitch angle measurement for a point P on the target,
Figure BDA0001385598950000046
the azimuthal measurement for a point P on the target,
Figure BDA0001385598950000047
RY(γ)、
Figure BDA0001385598950000048
respectively for counter-clockwise rotation about the X' axis
Figure BDA0001385598950000049
Angle, counterclockwise rotation of the gamma angle about the Y axis, counterclockwise rotation of the Z axis
Figure BDA00013855989500000410
A rotation matrix of angles, the rotation matrix being as follows:
Figure BDA00013855989500000411
by substituting the formula (5) and the formula (7) into the formula (6), the normal vector of the 45 ° rotating mirror in the O-XYZ coordinate system can be obtained as follows:
Figure BDA00013855989500000412
the incident light vector is initially
Figure BDA0001385598950000051
Is changed into after the cradle head rotates
Figure BDA0001385598950000052
From the vector form of the law of light reflection
Figure BDA0001385598950000053
Calculating an emergent light vector of
Figure BDA0001385598950000054
According to the conversion relation between the spherical coordinates and the rectangular coordinates, the true values of the azimuth angle and the pitch angle can be obtained according to the following formula (9)
Figure BDA0001385598950000055
Figure BDA0001385598950000056
The azimuth error is based on the trigonometric function approximation principle
Figure BDA0001385598950000057
Error from said pitch angle
Figure BDA0001385598950000058
Can be approximated as follows:
Figure BDA0001385598950000059
the obtained angle measurement error model of the self-made laser radar three-dimensional imaging system comprises the azimuth error
Figure BDA00013855989500000510
Error from pitch angle
Figure BDA00013855989500000511
Describing the angle measurement error (azimuth error)
Figure BDA00013855989500000512
Error in pitch angle
Figure BDA00013855989500000513
) And said perpendicularity error γ and said azimuth angle
Figure BDA00013855989500000514
The pitch angle
Figure BDA00013855989500000515
A mathematical relationship therebetween;
according to the trigonometric function approximation principle that sin gamma is gamma, cos gamma is 1, and high-order terms of part gamma are reasonably omitted, the simplified angle measurement error model of the homemade laser radar three-dimensional imaging system is obtained as follows:
Figure BDA00013855989500000516
converting an angle measurement error model in the homemade laser radar three-dimensional imaging system spherical coordinate system into a point cloud error model in the homemade laser radar three-dimensional imaging system rectangular coordinate system; the one-dimensional distance L and the azimuth angle of a point P on the target can be directly obtained after the self-made laser radar three-dimensional imaging system scans
Figure BDA00013855989500000517
And the pitch angle
Figure BDA00013855989500000518
According to the formula (9), converting the measured value into a rectangular coordinate system of the self-made laser radar three-dimensional imaging system to obtain a space three-dimensional coordinate (x, y, z) of a point P on the targetT；
Due to the presence of the distance measurement error Δ L and the angle measurement errorDifference (azimuth error)
Figure BDA00013855989500000519
Error in pitch angle
Figure BDA00013855989500000520
) A coordinate measurement of a point P on the target is P' (x + Δ x, y + Δ y, z + Δ z), where (Δ x, Δ y, Δ z)TAnd obtaining the self-made laser radar three-dimensional imaging system point cloud error model as follows according to an error transfer formula for the point cloud error of the target:
Figure BDA00013855989500000521
converting the coordinates of the target in the high-precision three-dimensional scanner into the homemade laser radar three-dimensional imaging system; the perpendicularity error gamma in the self-made laser radar three-dimensional imaging system point cloud error model is unknown and is not easy to measure, so that the perpendicularity error gamma is solved by utilizing the self-made laser radar three-dimensional imaging system and the point cloud coordinate data in the high-precision three-dimensional scanner to realize point cloud error correction; scanning N targets by using the self-made laser radar three-dimensional imaging system to obtain the coordinates (x) of one point on all the targets under the self-made laser radar three-dimensional imaging system coordinate systemi,yi,zi)T(i ═ 1,2, …, N) as measured values; substituting the measured values into an equation (9) to obtain one-dimensional distances L of all the targetsiAnd a pitch angle
Figure BDA0001385598950000061
And azimuth angle
Figure BDA0001385598950000062
Scanning the same target by using the high-precision three-dimensional scanner to obtain the coordinate (x ') of one point on the target under the high-precision three-dimensional scanner coordinate system'i,y′i,z′i)T(i ═ 1,2, …, N); due to the (x)i,yi,zi)TAnd (x'i,y′i,z′i)TUnder different coordinate systems, so the (x'i,y′i,z′i)TConverting the real value into a coordinate system of the self-made laser radar three-dimensional imaging system to be used as a real value; the rotation matrix R and the translation vector T from the high-precision three-dimensional scanner to the self-made laser radar three-dimensional imaging system are expressed as follows:
Figure BDA0001385598950000063
Figure BDA0001385598950000064
in the formulas (13) and (14), a, b and c are respectively angles of anticlockwise rotation around each axis of the high-precision three-dimensional scanner coordinate system, and x0、y0、z0Are displacements in three directions of said X, Y, Z, respectively, said (x'i,y′i,z′i)TThe coordinates in the homemade laser radar three-dimensional imaging system are as follows:
Figure BDA0001385598950000065
solving model parameters in the point cloud error model of the self-made laser radar three-dimensional imaging system, namely the perpendicularity error gamma; the point cloud error model of the self-made laser radar three-dimensional imaging system can be written as follows:
Figure BDA0001385598950000066
the distance measurement error Δ LiMainly influenced by a ranging circuit in the self-made laser radar three-dimensional imaging system, and the one-dimensional distance LiA known constant within a certain range; will be (x)i,yi,zi) T, the (x'i,y′i,z′i)TThe one-dimensional distance LiThe azimuth angle
Figure BDA0001385598950000067
And the pitch angle
Figure BDA0001385598950000068
The rotation matrix R and the translation vector T (a, b, c, x) may be determined by solving 3 × N nonlinear equations based on the least square method, instead of equations (15) and (16)0,y0,z0) And 7 unknowns are included in the perpendicularity error gamma.
The solved perpendicularity error gamma is used for perfecting a point cloud error model of the self-made laser radar three-dimensional imaging system, and point cloud error correction of the perpendicularity error of the self-made laser radar three-dimensional imaging system is achieved; substituting the perpendicularity error gamma into a formula (11) and a formula (12) to obtain a point cloud error (delta x, delta y, delta z) of the self-made laser radar three-dimensional imaging systemTThe target point cloud coordinates (x, y, z) of the self-made laser radar three-dimensional imaging systemTOn the basis, the target point cloud coordinate (x + delta x, y + delta y, z + delta z) of the self-made laser radar three-dimensional imaging system after the verticality error gamma is corrected is obtainedT。
The target used for correcting the self-made laser radar three-dimensional imaging system perpendicularity error point cloud error comprises but is not limited to target balls, plane reflective targets and other objects capable of obtaining a point space coordinate on the target.
Drawings
FIG. 1 is a schematic spatial view of a homemade lidar three-dimensional imaging system scanning a target;
FIG. 2 is a schematic diagram of a point cloud error correction process of a self-made foundation laser radar perpendicularity error;
FIG. 3 is a schematic diagram of the perpendicularity error between the pitch axis and the azimuth axis in the coordinate system of the self-control system;
FIG. 4 is a simulation result of the change of angle measurement error during the full-scale scanning process of the self-made system;
FIG. 5 is a comparison of the angle measurement error simulation before and after simplification of the angle measurement error model of the self-made system;
FIG. 6 is a schematic flow chart of parameter establishment in a point cloud error model of a self-made system;
FIG. 7 is a schematic diagram of a scanning scheme for parameter establishment in a point cloud error model of a self-made system;
Detailed Description
The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings. A flow schematic diagram of a point cloud error correction method based on the self-made foundation laser radar perpendicularity error is shown in figure 2, a coordinate system O-XYZ of a self-made laser radar three-dimensional imaging system (713) under an ideal condition is established, because the perpendicularity error gamma (301) exists between a pitching axis X' axis (204) and an azimuth axis Z axis (203) of the self-made system under an actual condition, the influence of the perpendicularity error gamma (301) on the angle measurement error of the self-made laser radar three-dimensional imaging system (713) is theoretically deduced under the coordinate system of the self-made laser radar three-dimensional imaging system (713), and an angle measurement error model of the self-made laser radar three-dimensional. And simplifying the angle measurement error model of the self-made laser radar three-dimensional imaging system (713) according to a trigonometric function approximation principle. And according to an error transfer principle, converting the angle measurement error model of the self-made laser radar three-dimensional imaging system (713) into a rectangular coordinate system to obtain a point cloud error model of the self-made laser radar three-dimensional imaging system (713). The same target ball (701-plus 712) is scanned by using a self-made laser radar three-dimensional imaging system (713) and a high-precision three-dimensional scanner (714), two groups of target point cloud data are respectively obtained, after the coordinate system unification is realized, the data are substituted into point cloud errors (specification expressions (15) and (16)) of the self-made laser radar three-dimensional imaging system (713), model parameters, namely perpendicularity error gamma (301), are solved, and the result is used for realizing the error correction of the point cloud of the self-made laser radar three-dimensional imaging system (713). Therefore, the specific implementation scheme can be divided into four steps: the method comprises the steps of establishing a self-made laser radar three-dimensional imaging system angle measurement error model, simplifying the self-made laser radar three-dimensional imaging system angle measurement error model, establishing the self-made laser radar three-dimensional imaging system point cloud error model and solving and correcting parameters of the model.
(1) Establishment of angle measurement error model of self-made laser radar three-dimensional imaging system
The space schematic diagram of the homemade laser radar three-dimensional imaging system (713) for scanning the target (106) is shown in fig. 1, when the homemade laser radar three-dimensional imaging system (713) scans, laser (105) enters a point O at the center of the 45-degree rotating mirror (103) after passing through the optical system (101), and the point is used as a coordinate origin. The motor (102) controls the 45-degree rotating mirror (103) to rotate vertically, the rotating shaft of the motor (102) is ideally a pitch shaft and is overlapped with the X axis (201), and the positive direction of the X axis (201) is the same as the incidence direction of the laser (105). Meanwhile, the holder (104) horizontally rotates around the vertical axis, the Z axis (203) is superposed with the vertical axis, and the positive direction is vertical upwards. And establishing a right-hand coordinate system, and considering that the initial laser emitting direction is the positive direction of the Y axis (202), thereby realizing the scanning of the three-dimensional space.
A schematic diagram of the perpendicularity error (301) of the pitch axis and the azimuth axis in the coordinate system of the homemade laser radar three-dimensional imaging system (713) is shown in fig. 1 and 3, the pitch axis is an X ' axis (204) in an actual situation, and an error angle gamma (301) exists between the pitch axis and an X axis (201) of an ideal situation, so that another O-X ' YZ ' coordinate system is established. The target object (106) is a target ball, any point on the target ball is a P point (107), the emergent ray is considered to pass through the P point (107) in the space, and the azimuth angle (302) and the pitch angle (303) of the emergent laser are respectively measured as
Figure BDA0001385598950000081
And
Figure BDA0001385598950000082
the normal vector of the 45 DEG rotating mirror (103) in the O-XYZ coordinate system is as follows:
Figure BDA0001385598950000083
the vector of the incident light (105) is known, and the vector of the emergent light can be obtained from the vector form of the reflection law
Figure BDA0001385598950000084
According to the conversion relationship between the spherical coordinates and the rectangular coordinates, as shown in formula (9), the method can obtainTrue values of azimuth angle (302) and pitch angle (303)
Figure BDA0001385598950000085
Error of azimuth angle according to trigonometric function approximation principle
Figure BDA0001385598950000086
Error from pitch angle
Figure BDA0001385598950000087
Can be approximated as follows:
Figure BDA0001385598950000088
the finally established angle measurement error model of the self-made laser radar three-dimensional imaging system (713) comprises azimuth angle errors
Figure BDA0001385598950000089
Error from pitch angle
Figure BDA00013855989500000810
The error model results are as follows:
Figure BDA00013855989500000811
Figure BDA00013855989500000812
therefore, the angle measurement error (azimuth angle error) of the self-made laser radar three-dimensional imaging system (713)
Figure BDA00013855989500000813
Error in pitch angle
Figure BDA00013855989500000814
) Affected by the perpendicularity error gamma (301) and the azimuth angle (302) and the pitch angle (303). Supposing that the verticality error (301) parameter of the self-made laser radar three-dimensional imaging system (713) is gamma-5', and the vertical scanning range is
Figure BDA00013855989500000815
The horizontal scanning range is
Figure BDA00013855989500000816
Angle measurement error (azimuth error) in full-range scanning process of self-made laser radar three-dimensional imaging system (713)
Figure BDA00013855989500000817
Error in pitch angle
Figure BDA00013855989500000818
) The simulation results of the changes are shown in fig. 4. The results show that: the angle measurement errors are not changed in the horizontal scanning process; azimuthal error during bottom-up vertical scanning
Figure BDA00013855989500000819
First decrease and then increase, and is at
Figure BDA00013855989500000820
Minimum value of 0, pitch angle error
Figure BDA00013855989500000821
Increasing first and then decreasing, also in
Figure BDA00013855989500000822
The maximum value is obtained, and the magnitude of angle measurement errors are all 10-5. The simulation result can visually display the change condition of the angle measurement error in the whole scanning process when a certain two-axis perpendicularity error (301) exists in the self-made laser radar three-dimensional imaging system (713).
(2) Simplification of angle measurement error model of self-made laser radar three-dimensional imaging system
The angle measurement error model of the self-made laser radar three-dimensional imaging system (713) is complex and needs to be reasonably simplified. According to the trigonometric function approximation principle that sin gamma is gamma, cos gamma is 1, and high-order terms of part gamma are reasonably omitted, the simplified angle measurement error model of the homemade laser radar three-dimensional imaging system (713) is obtained as follows:
Figure BDA0001385598950000091
assuming that the parameter of the verticality error (301) is gamma equal to 5', the vertical scanning range is
Figure BDA0001385598950000092
The horizontal scanning range is
Figure BDA0001385598950000093
The analysis shows that the angle measurement error of the homemade laser radar three-dimensional imaging system (713) caused by the perpendicularity error (301) only follows the pitch angle
Figure BDA0001385598950000094
(303) The results of the simulation comparison before and after the simplification of the angle measurement error model of the homemade laser radar three-dimensional imaging system (713) are shown in fig. 5. The results show that: simplified front and rear azimuth error
Figure BDA0001385598950000095
Error from pitch angle
Figure BDA0001385598950000096
Following pitch angle
Figure BDA0001385598950000097
(303) The measured values are the same in change, the model simplification process is correct, and the simplified model is used as an angle measurement error model of the self-made laser radar three-dimensional imaging system (713).
(3) Establishment of point cloud error model of self-made laser radar three-dimensional imaging system
The self-made laser radar three-dimensional imaging system (713) finally obtains and displays point cloud data of a target ball (106), and the data format is a three-dimensional space coordinate (x, y, z) of a target point (107) under a rectangular coordinate systemT(305) The coordinate transformation is related to equation (9), where L is a measure of the one-dimensional distance (304) to the target point,
Figure BDA0001385598950000098
is a measure of the target azimuth (302),
Figure BDA0001385598950000099
is a measure of pitch angle (303).
The self-made laser radar three-dimensional imaging system (713) point cloud error model is obtained by an error transfer formula as follows:
Figure BDA00013855989500000910
wherein Δ x, Δ y, Δ z are X, Y, Z axis (201-,
Figure BDA00013855989500000911
in order to be the system azimuth error,
Figure BDA00013855989500000912
the system pitch angle error can be represented by the angle measurement error model of the homemade laser radar three-dimensional imaging system (713).
(4) Parametric solution and correction of models
FIG. 6 shows a schematic flow chart of parameter establishment in a point cloud error model of a self-made lidar three-dimensional imaging system (713), in which N target spheres (701-doped ball 712) are taken as targets, the targets are respectively scanned by the self-made lidar three-dimensional imaging system (713) and a high-precision three-dimensional scanner (714), point cloud data of multiple points on each target sphere (701-doped ball 712) can be obtained, a least square method is used for performing spatial fitting on point clouds on each target sphere (701-doped ball 712), and a sphere center coordinate (x-coordinate) under the self-made lidar three-dimensional imaging system (713) is respectively obtainedi,yi,zi)T(i-1, 2, …, N) and a sphere center coordinate (x 'under the high-precision three-dimensional scanner (714)'i,y′i,z′i)T(i ═ 1,2, …, N). Will be (x'i,y′i,z′i)T,(i＝1,2, …, N) are rotated and translated to a coordinate system of a self-made laser radar three-dimensional imaging system (713), the rotation and translation are substituted into point cloud error expressions (15) and (16) of the self-made laser radar three-dimensional imaging system (713), a least square method is adopted to solve model parameters, and point cloud error correction of the self-made laser radar three-dimensional imaging system (713) is realized by obtaining a perpendicularity error gamma (301). The specific scanning scheme is as follows:
the schematic diagram of the scanning scheme established by the parameters in the point cloud error model of the home-made laser radar three-dimensional imaging system (713) is shown in fig. 7, where N is 12, that is, 12 target balls (701) are prepared and randomly distributed in an indoor open field, the home-made laser radar three-dimensional imaging system (713) is placed at the center, so that the target balls (701) and 712) are distributed in the horizontal scanning range of the home-made laser radar three-dimensional imaging system (713), the height of the target balls is distributed in the vertical scanning range of the home-made laser radar three-dimensional imaging system (713), the distance between each target ball (701 and 712) and the home-made laser radar three-dimensional imaging system (713) is approximately the same, and the ranging error is a known constant. Scanning all target balls (701-i,yi,zi)T(i 1,2, …,12) as a measured value, and finding the one-dimensional distance L of the center of each target sphere (701-i(304) And a pitch angle
Figure BDA0001385598950000101
(303) And azimuth angle
Figure BDA0001385598950000102
(302). Performing secondary scanning by using a high-precision three-dimensional scanner (714) to obtain the sphere center coordinates (x ') of all target spheres (701-'i,y′i,z′i)TAnd (i ═ 1,2, …,12), converting the coordinate system into a coordinate system of a homemade laser radar three-dimensional imaging system (713) through rotation and translation, and taking the coordinate system as a true value, wherein the rotation matrix R and the translation vector T are as follows:
Figure BDA0001385598950000103
Figure BDA0001385598950000104
wherein a, b and c are respectively the counterclockwise rotation angles around each axis of the coordinate system of the high-precision three-dimensional scanner (714), and x0、y0、z0The displacement in X, Y, Z (201-:
Figure BDA0001385598950000105
the above model has a, b, c, x0,y0,z0γ is a total of 7 unknown parameters, and 12 nonlinear equations can be obtained by substituting the sphere center coordinates of 4 target spheres (701, 704, 707, 710) into equation (19). Firstly, assuming that perpendicularity error gamma (301) does not exist, namely the right side of the equal sign of the formula (19) is 0, substituting the coordinate data of the sphere centers of target spheres (701, 704, 707 and 710), solving a, b, c and x by adopting a least square method to solve a nonlinear equation system0,y0,z0Default perpendicularity error γ (301) is initially 0. After the initial value is determined, 7 unknown parameters are solved by adopting a least square method, the verticality error gamma (301) is substituted into the formula (11) and the formula (12), and the system point cloud errors (delta x, delta y, delta z) are obtainedTThe model is checked by utilizing the coordinate data of the centers of the rest 8 target spheres (702, 703, 705, 706, 708, 709, 711 and 712), the model is continuously corrected, the finally obtained model can realize the point cloud error correction of the verticality error gamma (301) of the self-made laser radar three-dimensional imaging system (713), and the corrected target point cloud coordinates are (x + delta x, y + delta y, z + delta z)T。
In conclusion, the invention provides a point cloud error correction method based on the self-made foundation laser radar perpendicularity error, which mainly aims at the scanning mode that a self-made laser radar three-dimensional imaging system rotates by matching a 45-degree rotating mirror with a holder, establishes a self-made laser radar three-dimensional imaging system point cloud error model by calculating the influence of the perpendicularity error of a pitch axis and an azimuth axis on the angle measurement error of the self-made laser radar three-dimensional imaging system, and solves the perpendicularity error by using the point cloud coordinate of a high-precision three-dimensional scanner as a true value, thereby realizing the error correction of the target point cloud of the self-made laser radar three-dimensional imaging. The invention relates to a system point cloud error correction method which is started from a self-made laser radar three-dimensional imaging system error source, can be realized by utilizing a small number of target points and has stronger theoretical and logical properties, and the method is suitable for all three-dimensional scanning systems adopting a 45-degree rotating mirror matched pan-tilt rotating scanning mode.
The above description is only a basic scheme of the specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be conceived by those skilled in the art within the technical scope of the present invention disclosed herein are all covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Claims (8)

1. A point cloud error correction method based on self-made foundation laser radar perpendicularity error is characterized in that the method aims at a scanning mode that a 45-degree rotating mirror in a self-made laser radar three-dimensional imaging system is matched with a holder to rotate, wherein the self-made laser radar three-dimensional imaging system comprises an optical system, a scanning mechanism consisting of a motor and the 45-degree rotating mirror, and the holder; incident light is emitted to the center O point of the 45-degree rotating mirror through the optical system and is emitted from the homemade laser radar three-dimensional imaging system along with the vertical rotation of the scanning mechanism and the horizontal rotation of the holder; the ideal coordinate system O-XYZ of the self-made laser radar three-dimensional imaging system comprises an ideal pitch axis X axis, an initial emergent ray direction Y axis and an azimuth axis Z axis; on the basis of the ideal coordinate system O-XYZ, an included angle gamma exists between an X 'axis and an X axis of an actual pitching axis of the actual coordinate system O-X' YZ 'of the self-made laser radar three-dimensional imaging system, the Y axis is unchanged, and the Z' axis is established according to a right-hand coordinate rule; the perpendicularity error is defined as the actual pitch axis X'An included angle gamma between the axis and the X axis of the ideal pitching axis; a one-dimensional distance L of a point P on the target in the ideal coordinate system O-XYZ is defined as
Figure FDA0002368272670000011
Length, azimuth angle of
Figure FDA0002368272670000015
Is defined as
Figure FDA0002368272670000012
The included angle between the projection on the XOY plane and the X axis is positive in the anticlockwise direction from the positive half shaft of the X axis and ranges from 0 degree to 360 degrees, and the pitch angle is
Figure FDA0002368272670000016
Is defined as 90 DEG and
Figure FDA0002368272670000013
and the difference of the included angle between the Z axis and the Z axis, the one-dimensional distance L and the azimuth angle
Figure FDA00023682726700000110
And the pitch angle
Figure FDA0002368272670000017
The measurement errors are respectively a distance measurement error delta L and an azimuth angle error
Figure FDA0002368272670000018
And pitch angle error
Figure FDA0002368272670000019
Theoretically analyzing the influence of the perpendicularity error gamma on the angle measurement error of the self-made laser radar three-dimensional imaging system, wherein the angle measurement error of the self-made laser radar three-dimensional imaging system comprises the azimuth angle errorThe pitch angle error
Figure FDA00023682726700000112
Establishing an angle measurement error model of the self-made laser radar three-dimensional imaging system; the point cloud of the target is defined as the rectangular coordinates (x, y, z) of a point on the targetTThe point cloud error of a target is defined as the deviation (Δ x, Δ y, Δ z) of the coordinate measurement from the true value of the target point cloudTError of point cloud (Δ x, Δ y, Δ z) according to the targetTAnd the error transfer principle between the target angle measurement error and the target angle measurement error, wherein the target angle measurement error comprises the azimuth angle error
Figure FDA00023682726700000113
The pitch angle error
Figure FDA00023682726700000114
Establishing a point cloud error model of the self-made laser radar three-dimensional imaging system as follows:
Figure FDA0002368272670000014
obtaining the target point cloud coordinate after the self-made laser radar three-dimensional imaging system corrects the perpendicularity error gamma as follows:
(x+Δx,y+Δy,z+Δz)T
thereby realizing point cloud error correction of the self-made laser radar three-dimensional imaging system perpendicularity error gamma;
the method mainly comprises the following seven steps:
1) establishing an ideal coordinate system O-XYZ of the self-made laser radar three-dimensional imaging system, wherein the actual pitching axis is changed into an X 'axis and a Y axis is unchanged because the perpendicularity error exists between the actual pitching axis X' axis and an azimuth axis Z axis, namely an included angle gamma is formed between the actual pitching axis X 'axis and the ideal pitching axis X axis, and the Z' axis is established according to a right-hand coordinate rule to form the actual coordinate system O-X 'YZ' of the self-made laser radar three-dimensional imaging system; any one on the targetThe measured value of point P in the ideal coordinate system O-XYZ is the azimuth angle
Figure FDA00023682726700000115
Pitch angle
Figure FDA00023682726700000116
The true value of any point P on the target in the ideal coordinate system O-XYZ is an azimuth angle
Figure FDA00023682726700000117
Pitch angle
Figure FDA00023682726700000118
The above-mentioned
Figure FDA00023682726700000119
And
Figure FDA00023682726700000120
the difference being the azimuth error
Figure FDA00023682726700000121
The above-mentioned
Figure FDA0002368272670000025
And
Figure FDA0002368272670000026
the difference being pitch angle error
Figure FDA0002368272670000027
2) Establishing a self-made laser radar three-dimensional imaging system angle measurement error model caused by the perpendicularity error gamma; the model describes the azimuth error separately
Figure FDA0002368272670000028
The pitch angle error
Figure FDA0002368272670000029
And said perpendicularity error gamma and the azimuth of said target
Figure FDA00023682726700000210
Pitch angle
Figure FDA00023682726700000211
The mathematical relationship between them is as follows:
Figure FDA0002368272670000021
3) and carrying out approximate transformation on the trigonometric function value of the perpendicularity error gamma, and simplifying the angle measurement error model of the self-made laser radar three-dimensional imaging system as follows:
Figure FDA0002368272670000022
4) establishing point cloud errors (delta x, delta y, delta z) of the self-made laser radar three-dimensional imaging system according to an error transfer principleTWith said range error Δ L, said azimuth error
Figure FDA00023682726700000212
The pitch angle error
Figure FDA00023682726700000213
The mapping relationship between the two is as follows:
Figure FDA0002368272670000023
wherein L is a one-dimensional distance of any point on the target in an ideal coordinate system O-XYZ of the self-made laser radar three-dimensional imaging system, and Delta L is a measurement error of the one-dimensional distance L of any point on the target;
5) converting the angle measurement error model of the self-made laser radar three-dimensional imaging system into a rectangular coordinate system to obtain a point cloud error model of the self-made laser radar three-dimensional imaging system as follows:
Figure FDA0002368272670000024
6) scanning N targets by using the self-made laser radar three-dimensional imaging system to obtain coordinates (x) of the targets in the self-made laser radar three-dimensional imaging systemi,yi,zi)TWherein i is 1,2, …, N, as measured; performing secondary scanning on the target by using a high-precision three-dimensional scanner to obtain the coordinate (x ') of the target in the high-precision three-dimensional scanner'i,y′i,z′i)TConverting the i-1, 2, …, N into the self-made laser radar three-dimensional imaging system as a true value; the difference between the measured value and the actual value is the point cloud error (delta x) of the self-made laser radar three-dimensional imaging systemi,Δyi,Δzi)TWherein i ═ 1,2, …, N; obtaining the one-dimensional distance L of the target from the measured value according to the mapping relation between the spherical coordinate system and the rectangular coordinate systemiAzimuth angle
Figure FDA00023682726700000214
And a pitch angle
Figure FDA00023682726700000215
Range error Δ L of the targetiAt the one-dimensional distance LiA known constant when within a certain range;
7) solving model parameters in the self-made laser radar three-dimensional imaging system point cloud error model, namely the perpendicularity error gamma, and correcting the point cloud error of the self-made laser radar three-dimensional imaging system perpendicularity error gamma; point cloud error (delta x) of the self-made laser radar three-dimensional imaging systemi,Δyi,Δzi)TWhich isWhere i is 1,2, …, N, the one-dimensional distance L of the targetiAzimuth angle
Figure FDA0002368272670000034
Pitch angle
Figure FDA0002368272670000035
And a range error Δ LiSubstituting in an equation (4) to obtain 3 × N nonlinear equations, and determining the perpendicularity error gamma in the self-made laser radar three-dimensional imaging system point cloud error model by solving the nonlinear equations; substituting the perpendicularity error gamma into a formula (4) to obtain the target point cloud coordinate (x, y, z) of the self-made laser radar three-dimensional imaging systemTOn the basis, the target point cloud coordinate (x + delta x, y + delta y, z + delta z) corrected by the self-made laser radar three-dimensional imaging system is obtainedT。
2. The point cloud error correction method based on the self-made foundation laser radar perpendicularity error is characterized in that an ideal coordinate system O-XYZ of the self-made laser radar three-dimensional imaging system is established; an ideal pitch axis of the self-made laser radar three-dimensional imaging system is defined as a motor rotating shaft of the 45-degree rotating mirror, and an azimuth axis is defined as a rotating shaft of the holder; ideally, the ideal pitch axis and the azimuth axis are perpendicular to each other, and the perpendicularity error γ is 0; the center of the reflecting surface of the 45-degree rotating mirror, namely the intersection point of the incident light on the reflecting surface is a coordinate origin O; a coordinate axis which is coincident with the ideal pitch axis and has the same positive direction as the direction of the laser incident on the 45-degree rotating mirror is defined as an X axis; defining a coordinate axis which is the same as the initial emitting direction of the laser under an ideal condition as a Y axis; and the coordinate axis is coincident with the azimuth axis, and the coordinate axis vertically upward in the positive direction is defined as a Z axis.
3. The point cloud error correction method based on the homemade foundation laser radar perpendicularity error is characterized in that an angle measurement error model of the homemade laser radar three-dimensional imaging system caused by the perpendicularity error gamma is established and simplified; because the perpendicularity error gamma exists between the actual pitch axis X 'axis and the azimuth axis Z axis, namely an included angle gamma exists between the actual pitch axis X' axis and the ideal pitch axis X axis, the actual coordinate system O-X 'YZ' is established, and the establishing process of the angle measurement error model of the self-made laser radar three-dimensional imaging system is as follows:
under the actual coordinate system O-X 'YZ', the unit vector of the normal line of the 45-degree rotating mirror is initially as follows:
Figure FDA0002368272670000031
ideally, the outgoing ray passes through a point P on the target, and in this case, under the ideal coordinate system O-XYZ, the normal vector of the 45 ° turning mirror is:
Figure FDA0002368272670000032
in the formula (6)
Figure FDA0002368272670000036
The pitch angle measurement for a point P on the target,
Figure FDA0002368272670000037
the azimuthal measurement for a point P on the target,
Figure FDA0002368272670000033
respectively for counter-clockwise rotation about the X' axis
Figure FDA0002368272670000038
Angle, counterclockwise rotation of the gamma angle about the Y axis, counterclockwise rotation of the Z axis
Figure FDA00023682726700000410
A rotation matrix of angles, the rotation matrix being as follows:
Figure FDA0002368272670000041
by substituting the formula (5) and the formula (7) into the formula (6), the normal vector of the 45 ° rotating mirror in the O-XYZ coordinate system can be obtained as follows:
Figure FDA0002368272670000042
the incident light vector is initially
Figure FDA0002368272670000043
Is changed into after the cradle head rotates
Figure FDA0002368272670000044
From the vector form of the law of light reflection
Figure FDA0002368272670000045
Calculating an emergent light vector of
Figure FDA0002368272670000046
According to the conversion relation between the spherical coordinates and the rectangular coordinates, the true values of the azimuth angle and the pitch angle can be obtained according to the following formula (9)
Figure FDA00023682726700000411
Figure FDA0002368272670000047
The azimuth error is based on the trigonometric function approximation principle
Figure FDA00023682726700000412
Error from said pitch angle
Figure FDA00023682726700000413
Can be approximated as follows:
Figure FDA0002368272670000048
the obtained angle measurement error model of the self-made laser radar three-dimensional imaging system comprises the azimuth error
Figure FDA00023682726700000414
Error from pitch angle
Figure FDA00023682726700000415
Describing the azimuth error
Figure FDA00023682726700000417
The pitch angle error
Figure FDA00023682726700000416
And said perpendicularity error γ and said azimuth angle
Figure FDA00023682726700000418
The pitch angle
Figure FDA00023682726700000419
A mathematical relationship therebetween;
according to the trigonometric function approximation principle that sin gamma is gamma, cos gamma is 1, the simplified angle measurement error model of the home-made laser radar three-dimensional imaging system is obtained as follows:
Figure FDA0002368272670000049
in the formula (11), the high-order term of the portion γ is omitted.
4. The point cloud error correction method based on self-made foundation laser radar perpendicularity error according to claim 1, characterized in that the self-made foundation laser radar is three-dimensionally formedConverting an angle measurement error model in the spherical coordinate system of the image system into a point cloud error model in a rectangular coordinate system of the self-made laser radar three-dimensional imaging system; the one-dimensional distance L and the azimuth angle of a point P on the target can be directly obtained after the self-made laser radar three-dimensional imaging system scans
Figure FDA00023682726700000420
And the pitch angle
Figure FDA00023682726700000421
According to the conversion relation between the spherical coordinates and the rectangular coordinates, the measured value is converted to the rectangular coordinate system of the self-made laser radar three-dimensional imaging system to obtain the space three-dimensional coordinates (x, y, z) of a point P on the targetT；
Due to the presence of the range error Δ L and the azimuth error
Figure FDA0002368272670000054
The pitch angle error
Figure FDA0002368272670000055
The coordinate measurement of a point P on the target is P' (x + Δ x, y + Δ y, z + Δ z), where (Δ x, Δ y, Δ z)TFor the point cloud error of the target, according to an error transfer formula, the following can be obtained:
Figure FDA0002368272670000051
and the formula (12) is a point cloud error model of the self-made laser radar three-dimensional imaging system.
5. The point cloud error correction method based on the homemade foundation laser radar perpendicularity error according to claim 1, wherein coordinates of the target in the high-precision three-dimensional scanner are converted into the homemade laser radar three-dimensional imaging system; the perpendicularity in the point cloud error model of the self-made laser radar three-dimensional imaging systemThe error gamma is unknown and is not easy to measure, so the perpendicularity error gamma is solved by utilizing the self-made laser radar three-dimensional imaging system and the point cloud coordinate data in the high-precision three-dimensional scanner to realize point cloud error correction; scanning N targets by using the self-made laser radar three-dimensional imaging system to obtain the coordinates (x) of one point on all the targets under the self-made laser radar three-dimensional imaging system coordinate systemi,yi,zi)TWherein i is 1,2, …, N, as measured; obtaining the one-dimensional distances L of all the targets according to the conversion relation between the spherical coordinates and the rectangular coordinatesiAnd a pitch angle
Figure FDA0002368272670000056
And azimuth angle
Figure FDA0002368272670000057
Scanning the same target by using the high-precision three-dimensional scanner to obtain the coordinate (x ') of one point on the target under the high-precision three-dimensional scanner coordinate system'i,y′i,z′i)TWherein i ═ 1,2, …, N; due to (x)i,yi,zi)TAnd (x'i,y′i,z′i)TUnder different coordinate systems, so will be (x'i,y′i,z′i)TConverting the real value into a coordinate system of the self-made laser radar three-dimensional imaging system to be used as a real value; the rotation matrix R and the translation vector T from the high-precision three-dimensional scanner to the self-made laser radar three-dimensional imaging system are expressed as follows:
Figure FDA0002368272670000052
Figure FDA0002368272670000053
in the formulas (13) and (14), a, b and c are respectively inverses around each axis of the coordinate system of the high-precision three-dimensional scannerAngle of rotation of hour hand, x0、y0、z0Are displacements in the three directions of X, Y, Z, respectively, (x'i,y′i,z′i)TThe coordinates in the homemade laser radar three-dimensional imaging system are as follows:
Figure FDA0002368272670000061
(x ″) in formula (15)i,y″i,z″i)TIs (x'i,y′i,z′i)TAnd converting the coordinate into a coordinate in the self-made laser radar three-dimensional imaging system.
6. The point cloud error correction method based on the homemade foundation laser radar perpendicularity error is characterized in that model parameters in a point cloud error model of a homemade laser radar three-dimensional imaging system, namely the perpendicularity error gamma, are solved; the point cloud error model of the self-made laser radar three-dimensional imaging system can be written as follows:
Figure FDA0002368272670000062
the distance measurement error Δ LiMainly influenced by a ranging circuit in the self-made laser radar three-dimensional imaging system, and the one-dimensional distance LiA known constant within a certain range; will be (x)i,yi,zi)T(x'i,y′i,z′i)TThe one-dimensional distance LiThe azimuth angle
Figure FDA0002368272670000063
And the pitch angle
Figure FDA0002368272670000064
Substituting formula (16) and solving 3N nonlinear equations based on least square methodAnd determining the perpendicularity error gamma in the point cloud error model of the self-made laser radar three-dimensional imaging system.
7. The point cloud error correction method based on the self-made foundation laser radar perpendicularity error is characterized in that the solved perpendicularity error gamma is used for perfecting a point cloud error model of the self-made laser radar three-dimensional imaging system, and point cloud error correction of the self-made laser radar three-dimensional imaging system perpendicularity error is achieved; substituting the perpendicularity error gamma into a point cloud error model of the self-made laser radar three-dimensional imaging system to obtain a point cloud error (delta x, delta y, delta z) of the self-made laser radar three-dimensional imaging systemTThe target point cloud coordinates (x, y, z) of the self-made laser radar three-dimensional imaging systemTOn the basis, the target point cloud coordinate (x + delta x, y + delta y, z + delta z) of the self-made laser radar three-dimensional imaging system after the verticality error gamma is corrected is obtainedT。
8. The point cloud error correction method based on the home-made foundation laser radar perpendicularity error according to claim 1, wherein the target used for the home-made laser radar three-dimensional imaging system perpendicularity error point cloud error correction comprises a target ball and a planar retroreflective target.
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