阅读说明：本技术 基于外置式多目视觉设备的转台负载位姿测量方法和系统 (Turntable load pose measurement method and system based on external multi-view vision equipment ) 是由 曹动 曹力 于 2020-03-20 设计创作，主要内容包括：本发明提供了一种基于外置式多目视觉设备的转台负载的位姿测量方法和系统,该方法包括：在独立于转台的基座上固定设置光测设备,建立不耦合转台运动的世界坐标系；标定视觉设备的内外参数；在转台负载上设置标志点群,定义转台负载的负载中心和虚拟中心轴,构建负载坐标系,对标志点进行初值标校测量；转台动态工作过程中,用多目视觉设备对转台负载连续拍摄,对标志点群进行动态识别、匹配、定位和测量；解算转台工作过程中负载中心在世界坐标系下的坐标和虚拟中心轴的指向。本发明提供的技术方案通过外置的多目视觉设备进行负载位姿测量,克服了传统测量装置随被测物运动而带来的误差耦合,提高了负载位姿测量精度。(The invention provides a method and a system for measuring the pose of a turntable load based on an external multi-view vision device, wherein the method comprises the following steps: fixedly arranging optical measurement equipment on a base independent of the rotary table, and establishing a world coordinate system which is not coupled with the rotary table to move; calibrating internal and external parameters of the visual equipment; setting a mark point group on the turntable load, defining a load center and a virtual central axis of the turntable load, constructing a load coordinate system, and performing initial value calibration measurement on the mark points; in the dynamic working process of the rotary table, continuously shooting the rotary table load by using multi-view vision equipment, and dynamically identifying, matching, positioning and measuring the mark point group; and resolving the coordinates of the load center under the world coordinate system and the pointing direction of the virtual center shaft in the working process of the turntable. According to the technical scheme provided by the invention, the load pose is measured by the external multi-view vision equipment, so that the error coupling caused by the movement of the traditional measuring device along with the measured object is overcome, and the measurement precision of the load pose is improved.)

1. A rotary table load pose measurement method based on an external multi-view vision device is characterized in that the multi-view vision device comprises at least two optical measurement devices, a base and a computer system; the method comprises the following steps:

placing the base around a turntable, wherein the base is decoupled from the turntable in motion;

fixedly arranging each optical measurement device in the multi-view vision device on the base, fixedly arranging a turntable load on a turntable, and enabling the turntable load to rotate along with the turntable;

enabling the turntable load to be in a common view field of each optical measurement device, establishing a world coordinate system on the base, establishing a camera coordinate system by taking the principal point of each optical measurement device as an origin, and calibrating internal and external parameters of the optical measurement devices; establishing a load coordinate system on the turntable load, and defining a load center and a virtual central axis in the load coordinate system; arranging a mark point group on the load surface of the rotary table, wherein the mark point group comprises at least six mark points, and the mark points are not coplanar;

acquiring initial coordinate values of the mark points in the load coordinate system through calibration measurement;

in operation, the revolving stage takes the load to rotate, through every photometric device of computer system linkage to the revolving stage load carry out the position appearance and measure, include:

s1, acquiring and measuring images of the mark points through the optical measurement devices, and determining two-dimensional image coordinates of the mark points in the camera coordinate systems;

s2, matching and resolving two-dimensional images of the mark points in the camera coordinate systems according to the internal and external parameters of the optical measurement equipment, and acquiring space coordinates of the mark points in a world coordinate system;

s3, calculating the transformation translation relation between the load coordinate system and the world coordinate system by combining the initial coordinate values of the marker points in the load coordinate system and the space coordinates of the marker points in the world coordinate system;

and S4, calculating the coordinates of the load center and the pointing direction of the virtual center axis in the world coordinate system.

2. The method according to claim 1, further comprising expanding at least two photometric devices in the multi-vision device into a plurality of photometric devices distributed around a turret load by information fusion and matching settings.

3. The turntable load pose measuring method according to claim 1, wherein the method of setting the marker point group on the turntable load surface comprises discretely arranging the marker points along the virtual central axis direction.

4. The utility model provides a revolving stage load position appearance measurement system based on external many meshes visual equipment which characterized in that includes:

the rotary table is provided with at least one free rotation dimension and is used for bearing loads and realizing rotation;

the turntable load is fixedly arranged on the turntable and rotates along with the turntable, a load center and a virtual central shaft are defined on the turntable load, a mark point group is arranged on the surface of the turntable load, and the mark point group comprises at least six mark points with different surfaces;

the multi-view vision equipment comprises a base and at least two optical measurement devices, wherein the base is fixedly arranged around the rotary table, the base is in motion decoupling with the rotary table, and the optical measurement devices are fixedly arranged on the base and used for acquiring a two-dimensional image sequence of a mark point group on the rotary table load on time;

and the computer system is used for presetting an image acquisition rule of the multi-view vision equipment, identifying, matching, positioning and measuring each mark point in the mark point group in the two-dimensional image according to the preset rule, and calculating the load center coordinate and the virtual center axis direction of the turntable at different moments.

5. A pose measurement system according to claim 4, wherein the at least two photometric devices are distributed around the turret load.

Technical Field

The invention belongs to the field of vision measurement and image detection, and particularly relates to a turntable load pose measurement method and system based on an external multi-view vision device.

Background

The rotary table is a complex modern device integrating the light collector and the electricity, mainly provides high-precision rotation and accurate positioning, and can be divided into a single-shaft rotary table, a double-shaft rotary table, a three-shaft rotary table and a multi-shaft rotary table system according to a rotating shaft. The turntable is widely applied to the fields of scientific research, industrial production and the like, and is widely applied to the fields of inertial navigation device testing, antenna testing, laser testing, electronic product testing, analog simulation, space communication, space accurate positioning and the like. If it is used in semi-physical simulation and test in aviation and aerospace field, it plays a key role in developing aircraft, it can simulate various attitude angle movements of aircraft, reproduce various dynamics characteristics of its movement, repeatedly test the performances of guidance system, control system and correspondent devices of aircraft, obtain sufficient test data, and redesign and improve the system according to the data, so as to meet the performance index requirements of aircraft overall design. And for example, a war chariot defense system needs to effectively interfere with guided weapons such as laser, infrared or television and the like, so that the guided weapons are dazzled and blinded, important places and targets are protected, the comprehensive photoelectric interference weapons are integrated on hangers on two sides of a two-dimensional turntable, the direction of the turntable determines the direction of the photoelectric interference weapons, and the direction accuracy of the two-dimensional turntable plays a decisive role in defense hit rate.

In the prior art, the pointing accuracy and the position accuracy of the rotary table are optimized through the machining accuracy and the installation of the rotary table, the high-accuracy angle measurement is guaranteed by adopting a coaxial high-accuracy coding disc, the accuracy is improved based on the optimization and the improvement of the structure and the assembly form of the rotary table, and the geometric deviation between shafts of the rotary table, the installation eccentricity and the error caused by the unsmooth rotation are reduced. Many researchers and scholars also make intensive researches on the error generation reasons of the 2-axis, axis and even multi-axis rotary tables, error mathematical models, error correction and compensation methods and the like, and obtain many scientific achievements. However, the practice of applying the results of these studies to improve the precision of the turntable has increased the manufacturing cost of the turntable, and also has high precision requirement of the servo control of the turntable, so that the cost of the high-precision turntable often exceeds the range that the ordinary user can bear.

The core function of the turntable in the current application is considered, and the load center position precision and the load pointing precision of the turntable are the basis of the tracking precision and the angle measurement precision of the system. At present, the rotary table provides the load direction of the rotary table at different moments with high precision by means of checking initial values during the installation of the load of the rotary table at the earlier stage and the measurement of a shaft encoder of the rotary table, and reliable high-precision input is provided for subsequent measurement or tracking and the like. The measurement of the high-precision shaft coding disc commonly used in the industry at present is integrated into a movable platform of the rotary table, and the initial value error, the deviation in the dynamic state, the jitter, the coupling of multi-dimensional motion and the like of the installation of the high-precision shaft coding disc cause the realization difficulty of the high-precision measurement of the load orientation of the rotary table to be large, and the cost is high. Based on the technical scheme, the invention is superior to the conventional measurement framework in the prior industry, adopts an external multi-view vision device decoupled from the motion of the rotary table to dynamically and real-timely observe the motion of the rotary table load, and dynamically and high-precisely gives the central position of the rotary table load, the direction of the virtual central shaft and the like at different moments by comprehensively utilizing non-contact measurement technologies such as a high-speed photogrammetry technology, a real-time image processing technology, a high-precision multi-view (binocular) intersection measurement technology and the like. The decoupling external multi-view vision device can greatly reduce the requirements on the rotary table, the structure of the rotary table can be greatly simplified, the rotary table can be effectively miniaturized and lightened, the maneuverability of a measuring system is greatly improved, and the manufacturing cost is greatly reduced.

Disclosure of Invention

Based on this, the invention aims to solve the problem of measurement error coupling caused by the movement of the traditional measuring device along with the measured object, and solve the problems of high cost of manufacturing a high-precision turntable and low efficiency in adjustment.

The purpose of the invention is realized by the following technical scheme:

a rotary table load pose measurement method based on an external multi-view vision device is disclosed, wherein the multi-view vision device comprises at least two optical measurement devices, a base and a computer system; the method comprises the following steps:

placing the base around a turntable, wherein the base is decoupled from the turntable in motion;

fixedly arranging each optical measurement device in the multi-view vision device on the base, fixedly arranging a turntable load on a turntable, and enabling the turntable load to rotate along with the turntable;

enabling the turntable load to be in a common view field of each optical measurement device, establishing a world coordinate system on the base, establishing a camera coordinate system by taking the principal point of each optical measurement device as an origin, and calibrating internal and external parameters of the optical measurement devices; establishing a load coordinate system on the turntable load, and defining a load center and a virtual central axis in the load coordinate system; arranging a mark point group on the load surface of the rotary table, wherein the mark point group comprises at least six mark points, and the mark points are not coplanar;

acquiring initial coordinate values of the mark points in the load coordinate system through calibration measurement;

in operation, the revolving stage takes the load to rotate, through every photometric device of computer system linkage to the revolving stage load carry out the position appearance and measure, include:

s1, acquiring and measuring images of the mark points through the optical measurement devices, and determining two-dimensional image coordinates of the mark points in the camera coordinate systems;

s2, matching and resolving two-dimensional images of the mark points in the camera coordinate systems according to the internal and external parameters of the optical measurement equipment, and acquiring space coordinates of the mark points in a world coordinate system;

s3, calculating the transformation translation relation between the load coordinate system and the world coordinate system by combining the initial coordinate values of the marker points in the load coordinate system and the space coordinates of the marker points in the world coordinate system;

and S4, calculating the coordinates of the load center and the pointing direction of the virtual center axis in the world coordinate system.

Preferably, the method further comprises expanding at least two photometric devices in the multi-vision device into a plurality of photometric devices distributed around the turret load by means of an information fusion and matching setup.

Preferably, the method of arranging the marker point group on the turntable load surface includes discretely arranging the marker points along the virtual central axis direction.

In addition, still provide a revolving stage load position appearance measurement system based on external many meshes visual equipment, include:

the rotary table is provided with at least one free rotation dimension and is used for bearing loads and realizing rotation;

the turntable load is fixedly arranged on the turntable and rotates along with the turntable, a load center and a virtual central shaft are defined on the turntable load, a mark point group is arranged on the surface of the turntable load, and the mark point group comprises at least six mark points with different surfaces;

the multi-view vision equipment comprises a base and at least two optical measurement devices, wherein the base is fixedly arranged around the rotary table, the base is in motion decoupling with the rotary table, and the optical measurement devices are fixedly arranged on the base and used for acquiring a two-dimensional image sequence of a mark point group on the rotary table load on time;

and the computer system is used for presetting an image acquisition rule of the multi-view vision equipment, identifying, matching, positioning and measuring each mark point in the mark point group in the two-dimensional image according to the preset rule, and calculating the load center coordinate and the virtual center axis direction of the turntable at different moments.

Preferably, the at least two photometric devices are distributed around the turret load.

According to the scheme, the attitude measurement of the turntable load is realized through the external optical measurement equipment, and the invention has the following beneficial effects:

1) the problem of error coupling caused by the movement of a traditional measuring device along with a measured object is solved through the external vision equipment, a static system measures dynamic movement, and the measuring precision is improved;

2) helps to simplify the mechanical structure of the turntable, reduces the weight of the turntable, reduces the manufacturing requirement of the turntable, greatly reduces the cost of the turntable system,

3) the turntable assembling and debugging requirements and processes are simplified, and the system assembling and debugging efficiency is improved;

4) through the linkage of a computer system, the automation level of the measuring system is improved, and the control strategy of the rotary table is simplified.

Drawings

FIG. 1 is a flow chart of a method for measuring the rotary table load pose of an external multi-view vision device

FIG. 2 is a structural schematic diagram of a rotary table load pose measurement system of an external multi-view vision device

FIG. 3 is a schematic diagram of the spatial coordinate measurement of a single landmark point by binocular vision equipment

The reference numerals in the figures denote:

1. telescope system 21, first camera 22, second camera 23, third camera 3, mark point group 4, load center 5, virtual center axis 6, world coordinate system 7, load coordinate system 8, camera coordinate system

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the following detailed description of the embodiments of the present invention is provided in connection with the examples. It should be understood that the examples described herein are only for the purpose of illustrating the present invention, and are not intended to limit the scope of the present invention.

In the embodiment of the invention, without loss of generality, the optical measurement device specifically uses a camera, the turntable load specifically uses a telescope system 1, the telescope system 1 comprises a telescope body and a mechanical seat, and the specific selection of the turntable load does not limit the scope of the invention.

Example one

A method for measuring the rotary table load pose based on an external multi-view vision device comprises two optical measurement devices, a base and a computer system, wherein the two optical measurement devices are a first camera 21 and a second camera 22 respectively, and the rotary table load is a telescope system 1; the method comprises the following steps:

placing the base around the turntable, and decoupling the base from the turntable;

fixing a first camera 21 and a second camera 22 on a base, fixing a telescope system 1 on a turntable, and enabling the telescope system 1 to rotate along with the turntable;

enabling the telescope system 1 to be in a public view field of the first camera 21 and the second camera 22, establishing a world coordinate system 6 on the base, establishing a first camera coordinate system by taking a principal point of the first camera 21 as an origin, establishing a second camera coordinate system by taking a principal point of the second camera 22 as an origin, and calibrating internal and external parameters of the first camera 21 and the second camera 22; establishing a load coordinate system 7 on the telescope system 1, and defining a load center 4 and a virtual center shaft 5 in the load coordinate system 7; arranging a mark point group 3 on the surface of a body of the telescope system 1, wherein the mark point group 3 comprises at least six mark points, and each mark point is different in surface;

acquiring initial coordinate values of the mark points in the load coordinate system through calibration measurement;

in operation, the turntable rotates with a load, the first camera 21 and the second camera 22 are controlled by the computer system, and the pose measurement is performed on the telescope system 1, the specific steps of which are shown in fig. 1, and the flowchart of the method for measuring the pose of the turntable in the embodiment of the invention includes:

s1, acquiring and measuring images of the marker points in the marker point group 3 through the first camera 21 and the second camera 22, and determining two-dimensional image coordinates of the marker points in the camera coordinate systems 8;

s2, matching and resolving the mark points according to the internal and external parameters of the camera to obtain the space coordinates of the mark points in a world coordinate system 6;

s3, combining the initial coordinates of each mark point in the load coordinate system 7 and the space coordinates of each mark point in the world coordinate system 6, and resolving the translation conversion relation between the load coordinate system 7 and the world coordinate system 6;

at S4, the coordinates of the load center 4 and the orientation of the virtual center axis 5 in the world coordinate system 6 are calculated.

In the embodiment of the present invention, the marker point group 3 is provided discretely and with large redundancy along the direction of the virtual center axis 5 of the telescope system 1 outside the main body of the telescope system 1.

In the embodiment of the present invention, the calibration procedure of the initial value of the spatial coordinate of each marker point in the marker point group 3 in the load coordinate system 7 is as follows.

A load coordinate system 7 is established by taking a principal point (namely a load center 4) of the telescope system 1 as an origin of the coordinate system and taking an optical axis (namely a virtual central axis 5) of the telescope system as a Z axis. Set in the load coordinate system 7 as a marking point P_iHas the coordinates of (X)_i，Y_i，Z_i)，i＝1，2……n。

The first camera 21 is caused to capture an image of the marker point group 3, and the marker point P is measured in the camera coordinate system 8_iHas a two-dimensional image coordinate of p_i(x_i，y_i)i＝1,2……n。

And optionally selecting one mark point as a coordinate origin, and establishing a temporary coordinate system by taking a connecting line of the mark point and another mark point as a coordinate x-axis. Since the relative position between the marker point group 3 and the telescope system 1 is fixed, the rotational-translational matrix from the temporary coordinate system to the load coordinate system 7 is a constant, and is set to a ═ R (R)₀T₀)。

Suppose the transformation matrix from world coordinate system 6 to temporary coordinate system is B_i＝(R_iT_i) From the imaging relationship can be listed

Where ρ is a scale factor, K₀Is the internal reference matrix of the camera. In the matrix equation, A is unknown, and contains six unknowns, and the matrix equation can be obtained by rotating the rotary table for multiple imaging to obtain more than six equations. The system of equations contains the sine and cosine of the angle variable, rather than a linear system of equations, but can be searched for solution using a non-linear least squares method, such as the Levenberg-Marquardt method.

If the transformation translation matrix a from the temporary coordinate system to the load coordinate system 7 is already obtained, the initial values of the spatial coordinates of the marker points in the load coordinate system 7 can be calibrated.

In the embodiment of the invention, the distance between the two mark points with the farthest distance on the telescope system 1 is 1 meter, the observation public view field of the multi-view camera is 1m multiplied by 1m, the resolution of the camera is 2k multiplied by 2k, and the image extraction precision of the mark points is 0.1 pixel.

The actual spatial resolution precision measurable by the camera is as follows from the imaging principle

1000/2000×0.1＝0.05mm

The corresponding rotation angle of this resolution precision is:

(0.05/1000) × 57.296 ° -0.0029 ° -10.44 ″, i.e. an accuracy of 10 angular seconds.

From the above, the pointing positioning angle accuracy of the embodiment of the present invention is 10 arc seconds. Since the binocular cameras have the same resolution in the horizontal and vertical directions, the accuracy for the turntable pitch angle and the horizontal angle is 10 arc seconds.

Example two

In the embodiment of the invention, as shown in the schematic structural diagram of the turntable pose measurement system in fig. 2, three cameras, namely a first camera 21, a second camera 22 and a third camera 23, are selected as the optical measurement equipment.

Because the telescope system 1 can not guarantee that all the mark points on the outer wall of the telescope system 1 are shot by the two cameras in any rotating state in the rotating process, the spatial arrangement of the three cameras is adopted to solve the problem. Any mark point in any rotating state is ensured to be shot by at least more than two cameras at the same time. By increasing the number of cameras, more space information is provided, the measurement reliability is improved, the reconstruction precision can be mutually compensated, and the positioning precision can be theoretically improved. Meanwhile, the multi-view vision equipment has the redundancy positioning capability and can enhance the anti-noise capability of the system.

EXAMPLE III

In the embodiment of the invention, as shown in fig. 3, the binocular world device adopts the space coordinate measurement principle of a single mark point, and the specific steps are as follows.

And respectively establishing a first camera coordinate system and a second camera coordinate system, and obtaining a rotation matrix R and a translation vector T of each camera coordinate system 8 and a distortion parameter matrix of the camera by calibrating internal and external parameters of the camera. The index point is a point P, the spatial coordinates of which in the world coordinate system 6 are represented by (X, Y, Z), and the principal point coordinates of the first camera 21 are represented by (C)_x1,C_y1) The equivalent focal length of the first camera 21 is (F)_x1,F_y1). The first camera 21 is pairedThe mark point P is used for image acquisition, and the coordinate of the image point under the first camera coordinate system is (x)₁,y₁) The coordinates corrected according to the distortion parameter matrix model of the first camera 21 areThe collinear equation for the landmark point P and its image point P1 at the first camera 21 is

Similarly, a collinear equation between the marker point P and the image point P2 of the second camera 22 is established, and is obtained from the rotation matrix R and the translation vector T between the first camera coordinate system and the second camera coordinate system:

wherein the rotation matrixTranslation vector T ═ (Tx, Ty, Tz)

And the space coordinates of the mark point P in a world coordinate system can be solved by using a least square method to simultaneously establish the two groups of equations.

By analogy, the space coordinates of each mark point in the mark point group 3 under the world coordinate system 6 can be obtained, and the coordinates of the load center 4 of the telescope system 1 and the pointing direction of the virtual center shaft 5 under the world coordinate system are solved by combining the space coordinate initial values of each mark point under the load coordinate system 7, so that the posture of the telescope system 1 is obtained.

For the dynamically rotating turntable load, the photometric device adopts a high-speed camera to synchronously shoot, and spatial coordinates of a load center 4 and the direction of a virtual center shaft 5 in a world coordinate system 6 at different moments are acquired through a computer system, so that the attitude measurement of the telescope system 1 is realized.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and the specific implementations of the invention are not to be considered limited to these descriptions. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all should be considered as belonging to the protection scope of the invention.