阅读说明：本技术 基于激光雷达和室内gps系统的飞机大尺寸测量系统及方法 (Airplane large-size measurement system and method based on laser radar and indoor GPS (global positioning system) ) 是由 张刚 董富 于 2020-11-30 设计创作，主要内容包括：本发明涉及一种基于激光雷达和室内GPS系统的飞机大尺寸测量系统,包括安装有机器人的AGV小车、夹持在机器人机械手臂末端的激光雷达和标准坐标系参考板以及室内GPS系统；所述室内GPS系统建立有全局坐标系Q；所述室内GPS系统监测标准坐标系参考板在室内GPS系统建立全局坐标系Q下的位姿。本发明的目的是克服现有技术存在的测量效率低、转站频繁导致测量精度低等缺陷,提供一种基于激光雷达和室内GPS系统的飞机大尺寸测量系统及方法。(The invention relates to an aircraft large-size measuring system based on a laser radar and an indoor GPS system, which comprises an AGV trolley provided with a robot, a laser radar clamped at the tail end of a mechanical arm of the robot, a standard coordinate system reference plate and the indoor GPS system, wherein the reference plate is a standard coordinate system reference plate; the indoor GPS system is provided with a global coordinate system Q; and the indoor GPS system monitors the position of the reference plate of the standard coordinate system under the global coordinate system Q established by the indoor GPS system. The invention aims to overcome the defects of low measurement efficiency, low measurement precision caused by frequent station transfer and the like in the prior art, and provides a large-size airplane measurement system and method based on a laser radar and an indoor GPS system.)

1. The utility model provides an aircraft jumbo size measurement system based on laser radar and indoor GPS system which characterized in that: the system comprises an AGV trolley (10) provided with a robot, a laser radar (40) clamped at the tail end of a mechanical arm of the robot, a standard coordinate system reference plate (20) and an indoor GPS system (30); the indoor GPS system (30) is provided with a global coordinate system Q; the indoor GPS system (30) monitors the pose of the standard coordinate system reference plate (20) in a global coordinate system Q established by the indoor GPS system (30).

2. An aircraft large-size measurement system based on a laser radar and an indoor GPS system, according to claim 1, is characterized in that: when the large-size measuring system of the airplane works, the relative pose between the laser radar (40) and the reference plate (20) of the standard coordinate system is kept unchanged.

3. An aircraft large-size measurement system based on a laser radar and an indoor GPS system, according to claim 2, is characterized in that: the lidar (40) may establish a lidar coordinate system L.

4. An aircraft large-size measurement system based on a laser radar and an indoor GPS system, according to claim 1, 2 or 3, characterized in that: the standard coordinate system reference plate (20) is provided with three spherical receivers (21); the spherical centers of three spherical receivers (21) can establish a standard reference coordinate system S.

5. An aircraft large-size measurement system based on a laser radar and an indoor GPS system, according to claim 4, is characterized in that: the connecting lines of the three spherical receivers (21) are right-angled, and the distances from the spherical receivers (21) at two ends of the right-angled to the spherical receivers (21) at the right-angled are different.

6. An aircraft large-size measurement system based on a laser radar and an indoor GPS system, according to claim 5, is characterized in that: the indoor GPS system (30) comprises an IGPS transmitter (31), a spherical receiver (21) and a central processing unit, wherein the spherical receiver (21) and the central processing unit are respectively arranged on an indoor and standard coordinate system reference plate (20); the IGPS transmitter (31) is disposed at a plurality of positions of an indoor space.

7. A large-size airplane measuring method based on a laser radar and an indoor GPS system is characterized in that: an aircraft large-scale measurement system based on lidar and an indoor GPS system comprising any one of claims 1 to 6; further comprising the steps of:

the method comprises the following steps: calibrating an indoor GPS (global positioning system) system (30), calibrating the relation among all IGPS transmitters (31) by the indoor GPS system (30), and establishing a global coordinate system Q of the large-size measuring system of the airplane;

step two: determining the pose relationship between the laser radar coordinate system L and the standard reference coordinate system S through the calibration of the laser radar coordinate system L and the standard reference coordinate system S^ST_L：

Step three: the AGV trolley (10) carries a laser radar (40) to scan aircraft components for data acquisition, the laser radar scans at a plurality of stations to obtain point cloud data, and then the point cloud data are converted into a standard reference coordinate system S.

Step four: identifying the pose of the standard reference coordinate system S in the global coordinate system Q in real time;

step five: converting all the collected point cloud data into a global coordinate system Q

Step six: and processing the point cloud data through a central processing unit to complete the measurement of the large component of the airplane.

8. The method for measuring the large size of the airplane based on the laser radar and the indoor GPS system as claimed in claim 7, wherein the method comprises the following steps: in the second step^ST_LThe calculation formula of (2) is as follows:

^LT_S＝^LT_Q*^QT_S

^ST_L＝^LT_S ^-1

^LT_Qrepresenting the pose relationship between the global coordinate system Q relative to the lidar coordinate system L,^QT_Srepresenting the pose relationship between the standard reference coordinate system S relative to the global coordinate system Q.

9. The method for measuring the large size of the airplane based on the laser radar and the indoor GPS system as claimed in claim 8, wherein the method comprises the following steps: the above-mentioned^QT_SThe solving process of (2) is as follows: let the coordinates of the three spherical receivers (21) in the global coordinate system Q be (x) respectively_A,y_A,z_A)，(x_B,y_B,z_B)，(x_C,y_C,z_C). And establishing a global coordinate system Q by taking the point B as the center of a circle, and AB as the X axis of the standard reference coordinate system S, so that:

the position and posture relation of a standard reference coordinate system S relative to a global coordinate system Q is established by three points A, B, C^QT_S；

Wherein p ═ x_B,y_B,z_B)。

10. The method for measuring the large size of the airplane based on the laser radar and the indoor GPS system as claimed in claim 8, wherein the method comprises the following steps: the above-mentioned^LT_QThe solving process of (2) is as follows: 20 spherical receivers (21) are placed at proper positions in the indoor space, the 20 spherical receivers (21) can be scanned by the laser radar (40), and the full indoor space can be obtainedAnd (3) solving the pose relation between the global coordinate system Q and the laser radar coordinate system L by using the SVD method according to the coordinates under the local coordinate system Q, wherein the solving method comprises the following steps:

suppose there are two point groups p_iAnd q is_iWherein p is_iCoordinates of the point group q representing the 20 spherical receivers under the lidar_iRepresenting the coordinates of the point groups of the 20 spherical receivers in the global coordinate system, if the matrix relationship of the two point groups is solved by using the SVD decomposition method, the premise is that the centroids of the two point groups are coincided, if the two point groups are respectively usedTo represent a point group p_iAnd q is_iThus, there are:

wherein p is_i、q_i、Is a vector of 3 rows and 1 column representing the x, y, z coordinates of a point.

From the assumption of centroid coincidence, we have:

then, the following steps are carried out:

and finally solving a component least square function:

the SVD decomposition algorithm flow comprises the following steps:

(1) according to p_i、q_iComputingp_i' andp′_i

(2) computing a 3 x 3 matrix

Wherein p is_i' and q_i' is a vector of 3 rows and 1 column;

(3) SVD decomposition of H

H＝USV^T

(4) Calculating X ═ VU^T

(5) Determinant for calculation of X det (X)

If det (X) ═ 1, R ═ X; if det (x) ═ -1, the algorithm fails; after the rotation matrix R is obtained, the translation matrix t can be calculated by the following formula:

thus obtaining^LT_QAccording to^LT_S＝^LT_Q*^QT_SCalibrating a standard reference coordinate system S relative to the laserReach the pose relation of the coordinate system L and then according to^ST_L＝^LT_S ^-1And solving the relation between the laser radar coordinate system L and the standard reference coordinate system S.

Technical Field

The invention relates to the field of machine vision, in particular to an airplane large-size measuring system and method based on a laser radar and an indoor GPS system.

Background

With the development of advanced manufacturing technology in China, the digital measurement technology is widely applied to the fields of aerospace, aviation, ship manufacturing and the like. In particular, the digital large-size measuring system is gradually applied to the processing and assembling process of large-size workpieces of the airplane, and the assembly precision of the airplane is improved by using the high-precision measurement of the digital measuring system.

The digital large-size measurement technology is mainly divided into contact measurement and non-contact measurement at present, the contact measurement mainly comprises a laser tracker and indoor GPS measurement, and the non-contact measurement mainly comprises an electronic theodolite measurement system, a digital close-range industrial measurement system and a laser radar measurement system. When the surface of a large component of an airplane is measured, the non-contact measurement mode of the laser radar is preferred, because the laser radar can quickly and accurately measure in a large range, but the laser radar has the defects that the horizontal and vertical angle measurement ranges of the laser radar are limited, and the laser radar needs to frequently perform station switching operation, so that the accumulated error caused by station switching can be introduced. In addition, the current measuring system generally needs to occupy a large amount of space and is not mechanical. For aircraft manufacturing assembly plants, mobile measurement systems are highly desirable for aircraft large component measurements.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides an aircraft large-size measurement system and method based on a laser radar and an indoor GPS system.

The technical scheme for realizing the purpose of the invention is as follows: a large-size airplane measuring system based on a laser radar and an indoor GPS system comprises an AGV trolley provided with a robot, the laser radar clamped at the tail end of a mechanical arm of the robot, a reference plate of a standard coordinate system and the indoor GPS system; the indoor GPS system is provided with a global coordinate system Q; the indoor GPS system monitors the position and posture of the reference plate of the standard coordinate system under a global coordinate system Q established by the indoor GPS system.

Preferably, the relative pose between the laser radar and the reference plate of the standard coordinate system is kept unchanged when the large-size measuring system of the airplane works.

Preferably, the lidar is operable to establish a lidar coordinate system L.

Preferably, three spherical receivers are arranged on the reference plate of the standard coordinate system; the sphere centers of three of the spherical receivers can establish a standard reference coordinate system S.

Preferably, the connecting line of the three spherical receivers is a right angle, and the distances from the spherical receivers at two ends of the right angle to the spherical receivers at the right angle are different.

Preferably, the indoor GPS system comprises an IGPS transmitter, a spherical receiver and a central processor respectively arranged on the indoor and standard coordinate system reference plates; the IGPS transmitters are arranged at a plurality of positions of an indoor space.

A method for measuring the large size of an airplane based on a laser radar and an indoor GPS system comprises the airplane large size measuring system based on the laser radar and the indoor GPS system; further comprising the steps of:

the method comprises the following steps: calibrating an indoor GPS system, calibrating the relation among all IGPS transmitters by the indoor GPS system, and establishing a global coordinate system Q of a large-size measuring system of the airplane;

step two: determining the pose relationship between the laser radar coordinate system L and the standard reference coordinate system S through the calibration of the laser radar coordinate system L and the standard reference coordinate system S^ST_L：

Step three: the AGV carries a laser radar to scan an aircraft component for data acquisition, the laser radar scans at a plurality of stations to obtain point cloud data, and then the point cloud data are converted into a standard reference coordinate system S;

step four: identifying the pose of the standard reference coordinate system S in the global coordinate system Q in real time;

step five: converting all the collected point cloud data into a global coordinate system Q

Step six: and processing the point cloud data through a central processing unit to complete the measurement of the large component of the airplane.

Preferably, in said step two^ST_LThe calculation formula of (2) is as follows:

^LT_S＝^LT_Q*^QT_S

^ST_L＝^LT_S ^-1

^LT_Qrepresenting the pose relationship between the global coordinate system Q relative to the lidar coordinate system L,^QT_Srepresenting the pose relationship between the standard reference coordinate system S relative to the global coordinate system Q.

Preferably, the^QT_SThe solving process of (2) is as follows: let the coordinates of the three spherical receivers under the global coordinate system Q be (x) respectively_A,y_A,z_A)，(x_B,y_B,z_B)，(x_C,y_C,z_C). And establishing a global coordinate system Q by taking the point B as the center of a circle, and AB as the X axis of the standard reference coordinate system S, so that:

the position and posture relation of a standard reference coordinate system S relative to a global coordinate system Q is established by three points A, B, C^QT_S；

Wherein p ═ x_B,y_B,z_B)。

Preferably, the^LT_QThe solving process of (2) is as follows: placing 20 spherical receivers at appropriate positions in an indoor space to ensure that the spherical receivers can be scanned by a laser radar, obtaining coordinates of the spherical receivers under an indoor global coordinate system Q, and solving the pose relationship between the global coordinate system Q and a laser radar coordinate system L by using a SVD (singular value decomposition) method through the measured point pairs, wherein the solving method comprises the following steps:

suppose there are two point groups p_iAnd q is_iWherein p is_iCoordinates of the point group q representing the 20 spherical receivers under the lidar_iRepresenting the coordinates of the point groups of the 20 spherical receivers in the global coordinate system, if the matrix relationship of the two point groups is solved by using the SVD decomposition method, the premise is that the centroids of the two point groups are coincided, if the two point groups are respectively usedTo represent a point group p_iAnd q is_iThus, there are:

wherein p is_i、q_i、Is a vector of 3 rows and 1 column representing the x, y, z coordinates of a point.

From the assumption of centroid coincidence, we have:

then, the following steps are carried out:

and finally solving a component least square function:

the SVD decomposition algorithm flow comprises the following steps:

(1) according to p_i、q_iComputingp_i' andq_i'

(2) computing a 3 x 3 matrix

Wherein p is_i' and q_i' is a vector of 3 rows and 1 column;

(3) SVD decomposition of H

H＝USV^T

(4) Calculating X ═ VU^T

(5) Determinant for calculation of X det (X)

If det (X) ═ 1, R ═ X; if det (x) ═ -1, the algorithm fails; after the rotation matrix R is obtained, the translation matrix t can be calculated by the following formula:

thus obtaining^LT_QAccording to^LT_S＝^LT_Q*^QT_SCalibrating the pose relationship of the standard reference coordinate system S relative to the laser radar coordinate system L, and then calibrating the pose relationship according to the pose relationship^ST_L＝^LT_S ^-1And obtaining the pose relation of the laser radar coordinate system L relative to the standard reference coordinate system S.

After the technical scheme is adopted, the invention has the following positive effects:

(1) the invention takes the global coordinate system of the indoor GPS system as the global coordinate system, and converts all the measurement data of the laser radar at a plurality of stations into the global coordinate system, thereby reducing the accumulated error caused by station conversion.

(2) The calibration of the laser radar coordinate system and the standard reference system is a key part of the system, and the relative position relationship between the laser radar coordinate system and the standard reference coordinate system is kept unchanged during the operation of the system, so that only one calibration is needed, when the system starts to work subsequently, the laser radar converts data into the standard reference coordinate system, and then converts point cloud data from the standard reference coordinate system into measurement coordinates in real time according to the relative position relationship between the current standard reference coordinate system and indoor measurement coordinates.

(3) The indoor GPS system is a contact type measuring system, an IGPS transmitter is arranged in the space of the measuring system, the three-dimensional coordinates of a spherical receiver in the indoor GPS system can be detected, and the problems of light blocking or angle limitation do not exist.

(4) The invention avoids the problems of large workload, complicated calibration, low precision and the like caused by arranging the frog jumping balls on a large component in the prior art; the scheme needs less calibration, high measurement efficiency and strong real-time property.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a general layout of the system of the present invention;

FIG. 2 is a diagram of a spherical receiver of the present invention in a reference plate of a standard coordinate system;

FIG. 3 is a coordinate system relationship diagram of the present invention;

fig. 4 is a measurement flow chart of the present invention.

The reference numbers in the drawings are as follows: AGV dolly 10, standard coordinate system reference plate 20, spherical receiver 21, connecting rod 22, indoor GPS system 30, IGPS transmitter 31, lidar 40.

Detailed Description

(example 1)

Referring to fig. 1 to 3, the present invention includes an AGV cart 10 with a robot mounted thereon, a laser radar 40 clamped at the end of the robot arm, a reference plate 20 of a standard coordinate system, and an indoor GPS system 30; specifically, a reference plate 20 of a standard coordinate system is fixed at the tail end of a robot manipulator through a connecting plate 22 parallel to the ground, and a laser radar 40 is directly fixed at the lower end of the connecting position of the connecting plate 22 and the robot manipulator; the indoor GPS system 30 establishes a global coordinate system Q; the indoor GPS system 30 monitors the pose of the standard coordinate system reference plate 20 in the global coordinate system Q established by the indoor GPS system 30.

More specifically, in the present embodiment, the relative pose between the lidar 40 and the reference plate 20 of the standard coordinate system remains unchanged during the operation of the large-size measurement system of the aircraft.

The lidar 40 may establish a lidar coordinate system L.

The reference plate 20 of the standard coordinate system is provided with three spherical receivers 21; the centers of the three spherical receivers 21 establish a standard reference coordinate system S.

The connecting lines of the three spherical receivers 21 are right-angled, and the distances from the spherical receivers 21 at two ends of the right-angled to the spherical receivers 21 at the right-angled position (i.e., the origin) are different, so that the origin can be identified, the X-axis and the Y-axis can be distinguished conveniently, and a fixed standard reference coordinate system S is established.

The indoor GPS system 30 comprises an IGPS transmitter 31, a spherical receiver 21 and a central processor respectively arranged on the indoor and standard coordinate system reference plates 20; the IGPS transmitters 31 are disposed at a plurality of positions in the indoor space, and the specific arrangement point is required to satisfy that the spherical receivers 21 on the reference plate 20 of the standard coordinate system can receive signals of more than two IGPS transmitters 31, so that the coordinate positions of the spherical receivers 21 on the reference plate 20 of the standard coordinate system can be calculated.

(example 2)

Referring to fig. 4, a method for measuring a large size of an aircraft based on a laser radar and an indoor GPS system includes the system for measuring a large size of an aircraft based on a laser radar and an indoor GPS system described in embodiment 1; further comprising the steps of:

the method comprises the following steps: calibrating an indoor GPS system 30, calibrating the relation among all IGPS transmitters 31 by the indoor GPS system 30, and establishing a global coordinate system Q of the large-size measuring system of the airplane; the indoor GPS system 30 in the system is calibrated by adopting commercial software;

step two: determining the pose relationship between the laser radar coordinate system L and the standard reference coordinate system S through the calibration of the laser radar coordinate system L and the standard reference coordinate system S^ST_L：

Step three: the AGV trolley 10 carries a laser radar 40 to scan an aircraft component for data acquisition, the laser radar 40 scans at a plurality of stations to obtain point cloud data, and then the point cloud data are converted into a standard reference coordinate system S;

step four: identifying the pose of the standard reference coordinate system S in the global coordinate system Q in real time;

step five: converting all the collected point cloud data into a global coordinate system Q

Step six: processing the point cloud data through a central processing unit to complete the measurement of the large component of the airplane;

^LT_S＝^LT_Q*^QT_S

^ST_L＝^LT_S ^-1

^LT_Qrepresenting the pose relationship between the global coordinate system Q relative to the lidar coordinate system L,^QT_Srepresenting the pose relationship between the standard reference coordinate system S and the global coordinate system Q;

wherein the solution is^QT_SThe relationship between the standard reference coordinate system S and the global coordinate system Q is found, and when solving the relationship, the AGV 10 is made to move to an appropriate position in the indoor space with the laser radar 40 and the reference plate 20 of the standard coordinate system, and since the coordinate values of the three spherical receivers 21 on the reference plate 20 of the standard coordinate system under the global coordinate system Q of the indoor GPS system 30 can be obtained, the pose relationship of the coordinate system established by the three points relative to the global coordinate system Q can be solved.

Let the coordinates of the three spherical receivers 21 under the global coordinate system Q be (x) respectively_A,y_A,z_A)，(x_B,y_B,z_B)，(x_C,y_C,z_C). And establishing a global coordinate system Q by taking the point B as the center of a circle, and AB as the X axis of the standard reference coordinate system S, so that:

the position and posture relation of a standard reference coordinate system S established by three points A, B, C relative to a global coordinate system^QT_S；

Wherein p ═ x_B,y_B,z_B)；

Solving for^LT_QThat is, the pose relationship between the global coordinate system Q and the laser radar coordinate system L is solved, the position of the laser radar 40 is kept unchanged, 20 spherical receivers 21 are placed at suitable positions in the indoor space, it is ensured that the 20 spherical receivers 21 can be scanned by the laser radar 40, and meanwhile, the coordinates of the spherical receivers under the indoor global coordinate system Q can also be obtained, the pose relationship between the global coordinate system Q and the laser radar coordinate system L is solved by using the SVD method for the 20 measured point pairs, and the solving method is as follows:

suppose there are two point groups p_iAnd q is_iWherein p is_iCoordinates of the point group q representing the 20 spherical receivers under the lidar_iRepresents the coordinates of the 20 spherical receivers in the global coordinate system, where p_i、q_iIf the matrix relation of the two point groups is solved by using the SVD decomposition method, the premise assumption is that the centroids of the two point groups are coincided, if the two point groups are respectively usedTo represent a point group p_iAnd q is_iThus, there are:

wherein p is_i、q_i、Is a vector of 3 rows and 1 column representing the x, y, z coordinates of a point.

From the assumption of centroid coincidence, we have:

then, the following steps are carried out:

and finally solving a component least square function:

the SVD algorithm is well-established and detailed derivation is not described.

The SVD algorithm flow is as follows:

(1) according to p_i、q_iComputingp_i' andq_i'

(2) computing a 3 x 3 matrix

Wherein p is_i' and q_i' is a vector of 3 rows and 1 column;

(3) SVD decomposition of H

H＝USV^T

(4) Calculating X ═ VU^T

(5) Determinant for calculation of X det (X)

If det (X) ═ 1, R ═ X; if det (x) ═ -1, the algorithm fails; after the rotation matrix R is obtained, the translation matrix T can be calculated by the following formula:

thus obtaining^LT_QAccording to^LT_S＝^LT_Q*^QT_SCalibrating the pose relationship of the standard reference coordinate system S relative to the laser radar coordinate system L, and then calibrating the pose relationship according to the pose relationship^ST_L＝^LT_S ^-1And obtaining the pose relation of the laser radar coordinate system L relative to the standard reference coordinate system S.

The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.