CN110823170B - Large-section attitude-adjusting docking method of carrier rocket based on binocular vision measurement - Google Patents

Large-section attitude-adjusting docking method of carrier rocket based on binocular vision measurement Download PDF

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CN110823170B
CN110823170B CN201911102118.4A CN201911102118A CN110823170B CN 110823170 B CN110823170 B CN 110823170B CN 201911102118 A CN201911102118 A CN 201911102118A CN 110823170 B CN110823170 B CN 110823170B
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coordinate system
assembly
section
adjusting
axis
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CN110823170A (en
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张超鹏
石璟
王向东
陈勇
杨帆
李兴坤
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Sichuan Aerospace Changzheng Equipment Manufacturing Co Ltd
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Sichuan Aerospace Changzheng Equipment Manufacturing Co Ltd
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C3/00Measuring distances in line of sight; Optical rangefinders
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00Image analysis
    • G06T7/70Determining position or orientation of objects or cameras
    • G06T7/73Determining position or orientation of objects or cameras using feature-based methods
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06TIMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00Indexing scheme for image analysis or image enhancement
    • G06T2207/30Subject of image; Context of image processing
    • G06T2207/30108Industrial image inspection

Abstract

The invention discloses a binocular vision measurement-based posture-adjusting docking method for a large section of a carrier rocket, which comprises the following steps of: step one, establishing a global coordinate system; step two, establishing local coordinate systems of the two butt joint sections; step three, establishing an assembly coordinate system, and respectively determining a conversion relation matrix between two local coordinate systems and the assembly coordinate system; establishing a virtual pose adjusting coordinate system; and step five, determining the control quantity of each attitude adjusting control point in the assembly coordinate system. The invention provides a series of coordinate system calibration and conversion methods based on binocular vision guide automatic assembly, and control quantity obtained by vision measurement is distributed to each motion axis, so that rapid calibration of a section butt joint vision measurement system is realized, and the purposes of measurement and motion control are achieved.

Description

Large-section attitude-adjusting docking method of carrier rocket based on binocular vision measurement
Technical Field
The invention belongs to the field of measurement control, and particularly relates to a carrier rocket large-section attitude-adjusting docking motion calculation method based on binocular vision measurement, which is applied to automatic docking of carrier rocket section assembly.
Background
The method of manual assembly is adopted initially for assembly and butt joint of the aerospace carrier rocket sections, the assembly mode has poor working environment, high labor intensity, low assembly efficiency, more restriction factors of workers during assembly work and high uncertainty, so that the assembly mode is replaced by automatic assembly and has a necessary trend; at present, a mature automatic assembly mode is to realize automatic assembly butt joint by adopting the guidance of a laser tracker, but the assembly mode has large equipment investment, needs detailed calibration in each assembly and has higher requirements on the quality of operators.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides a large-section attitude-adjusting docking method of a carrier rocket based on binocular vision measurement, aiming at solving the following technical problems:
the invention aims to realize the rapid automatic butt joint of the carrier rocket section under the guidance of vision measurement, and provides the problems of the determination, the rapid calibration and the conversion of a coordinate system and the analysis of control quantity during automatic butt joint of a binocular vision measurement technology in the section butt joint;
selecting and calibrating a local coordinate system of a butt joint plane of the assembly section, and calculating a conversion relation between the local coordinate system and a global coordinate system;
selecting and calibrating an assembly coordinate system, selecting the assembly coordinate system as a target coordinate system for section butt joint, and taking an original point as a butt joint target point, so that the calculation difficulty of the pose deflection amount is reduced;
determining a calculation method of a conversion relation between an assembly coordinate system and a local section butt joint coordinate system, wherein the quantity obtained by a conversion matrix is the quantity of motion required by section butt joint;
selecting a local coordinate system of the attitude adjusting platform, calibrating the bracket of the attitude adjusting platform, and determining the conversion relation between the local coordinate system of the attitude adjusting platform and a global coordinate system;
providing a calculation method for establishing a virtual coordinate system of the attitude adjusting platform according to the local coordinate system of the attitude adjusting platform, and solving a conversion relation between the coordinate system of the attitude adjusting platform and a global coordinate system;
obtaining a conversion relation between the assembly coordinate system and the gesture adjusting coordinate system according to the conversion relation between the global coordinate system and the assembly coordinate system and the conversion relation between the global coordinate system and the gesture adjusting coordinate system;
and selecting a pose adjusting control point, establishing a section pose adjusting inverse solution model, obtaining the motion amount condition of each control axis under a pose adjusting coordinate system, and realizing automatic pose adjusting butt joint.
The technical scheme adopted by the invention for solving the technical problems is as follows: a binocular vision measurement-based posture-adjusting docking method for a large section of a carrier rocket comprises the following steps:
step one, establishing a global coordinate system Oq-XqYqZq
Step two, establishing a local coordinate system O of two butt joint sections1-X1Y1Z1、O2-X2Y2Z2
Step three, establishing an assembly coordinate system O-XYZ, and respectively determining two local coordinate systems O1-X1Y1Z1And O2-X2Y2Z2A conversion relation matrix between the assembly coordinate system and O-XYZ;
step four, establishing a virtual pose adjusting coordinate system Ot1-Xt1Yt1Zt1
And step five, determining the control quantity of each attitude adjusting control point in the assembly coordinate system.
Compared with the prior art, the invention has the following positive effects:
the invention provides a series of coordinate system calibration and conversion methods based on binocular vision guide automatic assembly, and control quantity obtained by vision measurement is distributed to each motion axis, so that rapid calibration of a section butt joint vision measurement system is realized, and the purposes of measurement and motion control are achieved. The calibration and the establishment of the coordinate system are simple and quick to operate, the training pressure on personnel is low, and the calibration speed is greatly improved; the motion control system adopts an open control mode of 'PC + motion control card', the vision detection system and the control system share one PC, the integration of vision measurement and motion control is realized, the kinematic inverse solution can be directly carried out on the measured value, and the motion control quantity of each axis is obtained. The concrete advantages include:
1) the calibration system based on the binocular vision measurement technology greatly simplifies the calibration steps and realizes quick calibration;
2) determining each coordinate system involved in the automatic assembly and docking process, and establishing a conversion relation of the coordinate system by proposing an algorithm;
3) through the coordinate system conversion relation, the motion amount required by realizing the butt joint is quickly calculated, a butt joint platform motion resolving model is established, and the motion amount of each axis for realizing the butt joint is obtained.
4) By adopting an open type motion control system, interface software can be written on a PC to complete the whole work of section assembly measurement and motion control.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic view of a vision measurement guided launch vehicle segment docking;
fig. 2 is a schematic view of a local coordinate system for docking of launch vehicle segments, wherein:
(a) a local docking reference system established on a docking plane of the docking section 1 and the docking section 2 of the carrier rocket;
(b) is a schematic diagram of the characteristic points of the section butt joint plane;
FIG. 3 is a schematic view of a docking assembly coordinate system for a launch vehicle segment;
FIG. 4 is a schematic view of a virtual pose adjustment coordinate system of the pose adjustment platform;
FIG. 5 is a schematic diagram of coordinate system rotation matrix transformation;
FIG. 6 is a schematic diagram of a projection of the posture adjusting mechanism for motion solution.
Detailed Description
A major segment attitude adjusting and docking method of a carrier rocket based on binocular vision measurement comprises the following steps: A. establishing a global coordinate system Oq-XqYqZqDetermining the relative position relation between the global coordinate system and the camera coordinate system; B. the large sections of the carrier rockets to be butted have respective local coordinate systems; C. establishing an assembly coordinate system O-XYZ as a target coordinate system for assembling the sections; D. adjusting the position and the attitude of the carrier rocket section to be consistent, thereby realizing the butt joint of an attitude adjusting coordinate system of the platform needing attitude adjustment; E. arranging measurement targets in the butt joint area of the carrier rocket section, and establishing a global coordinate system; F. at the end face of the large section of the carrier rocketArranging measurement target points, and determining a central point of the end face of the section and a local coordinate system of the end face of the section; G. arranging target points on the attitude adjusting platform by adding a holding mechanism, and establishing an attitude adjusting coordinate system; H. calculating a conversion relation between a global coordinate system and a local coordinate system; I. and calculating the conversion relation between the global coordinate system and the pose adjusting coordinate system. Finally, the attitude adjusting quantity of the section is decomposed to each moving axis of the attitude adjusting platform, so that the relative unification of the position relation of each coordinate system in the measuring system is realized, and data support is provided for the precise automatic butt joint of the large section.
1. The method is used for automatic butt joint of stages of a large section of a launch vehicle, and is based on a binocular vision measurement technology, four cameras are used in the binocular vision measurement system, every two cameras are in one group and divided into two groups of binocular vision systems which are respectively positioned at the front side and the rear side of the butt joint section; the detection field of view may be obstructed due to the fact that the section needing to be detected is too large, and the defect can be avoided in advance by adopting a measurement distribution mode of two groups of binocular vision systems.
Assembly coordinate system O with global coordinate system as a segment in the measuring systemq-XqYqZqGlobal coordinate system YqThe positive direction of the axis is vertical to the ground and faces downwards, XqAxis parallel to the docking platform track, ZqThe axial direction is determined by the right-hand rule, origin of coordinates OqIs positioned at any point on the calibration board. The position relation between the camera and the coordinate system of the camera is obtained by a linear calibration method, which is a mature camera internal and external parameter calibration method and is not discussed here.
2. The front and rear sections respectively establish a local coordinate system O1-X1Y1Z1、O2-X2Y2Z2。O1、O2The points are respectively located at the circle center of the front and rear section butt joint planes, Y1、Y2Pointing to quadrant I, X1、X2Respectively pointing to the course of the carrier rocket along the central axis of each section, Z1、Z2The direction is determined according to the right-hand rule. The coordinate system establishment and calibration steps are as follows:
the characteristic points of the section butt joint planes are positioning pin holes on the circumference which are respectively positionedThe pin hole butt joint mode is divided into butt joint and insertion joint, a target needs to be installed at the measuring point through a switching tool during calibration, and the position coordinates of the target are obtained by depending on the position precision of the positioning pin shaft. Taking section 1 docking plane as an example, in the global coordinate system Oq-XqYqZqThen, the coordinate values of the four target measuring points are marked as Ci(i=1,2,3,4),Ci=(Xqi,Yqi,Zqi);
From which three points are arbitrarily selected, represented by the formula (X)qi-XOq1)2+(Yqi-YOq1)2+(Zqi-ZOq1)2=R2(R is a known radius of the segment), O can be obtainedq1=(XOq1,YOq1,ZOq1). The central point O can be known by the permutation and combinationq1Presence of C4 34 values according to formula
Figure BDA0002270175120000051
The center of four values is obtained as the center point Oq1Thereby reducing the error.
In a local coordinate system O1-X1Y1Z1Next, the four target points are obtained by the size and position values of the pin shaft and are marked as Si(i=1,2,3,4),Si=(0,Y1i,Z1i);
From which three points are arbitrarily selected, represented by the formula (Y)1i-YO11)2+(Z1i-ZO11)2=R2(R is a known radius of the segment), O can be obtained11=(0,YO11,ZO11). The central point O can be known by the permutation and combination11Presence of C4 34 values according to formula
Figure BDA0002270175120000052
Figure BDA0002270175120000053
The center of four values is obtained as the center point O11Thereby, it is possible to obtainThe error is reduced.
In the same way, the circle center coordinate O of the section 2 in the global coordinate system of the butt joint plane can be obtainedq2Circle center coordinate O in local coordinate system22
3. Establishing an assembly coordinate system O-XYZ, wherein the directions of all axes of the assembly coordinate system are the same as the global coordinate system, and the origin of coordinates O is located at Oq1、Oq2The midpoint of the line. The steps of establishing the coordinate system and solving the conversion relation are as follows:
under the global coordinate system Oq=(Oq1+Oq2)/2. Therefore, the assembly coordinate system and the global coordinate system have a translation conversion relationOTOq
Figure BDA0002270175120000054
According to a conversion relationOTOqThe coordinate value C of the target point and the central point of the segment butt joint plane under the assembly coordinate system can be obtainedOi、OO1
Coordinate point COiAnd Si、OO1And O11For different coordinate systems O-XYZ and O1-X1Y1Z1The same spatial point below, and the coordinate values are known. Local coordinate system O1-X1Y1Z1The following conversion relation exists between the assembly coordinate system O-XYZ:
Figure BDA0002270175120000061
to obtain a local coordinate system O1-X1Y1Z1And a deflection relation matrix between the assembly coordinate system O-XYZ, firstly solving the center of a known point:
Figure BDA0002270175120000062
passing formula Cmi=COi-m,OmO1=OO1-m,Smi=Si-n,Om11=O11N, two coordinate systemsTranslating to the central point, and calculating the rotation transformation matrix by Newton iteration methodORO1Finally can find outOTO1
The local coordinate system O can be solved by the same method2-X2Y2Z2Conversion relation with assembly coordinate system O-XYZORO2OTO2
4. Establishing a local coordinate system O of the front bracketJ1-XJ1YJ1ZJ1Local coordinate system O of rear bracketJ2-XJ2YJ2ZJ2The directions of coordinate axes of the two coordinate systems are consistent with the direction of the global coordinate system, and the origin of coordinates OJ1、OJ2Are respectively positioned at the circle center of the bracket. The coordinate system establishment and transformation relation are calculated as follows:
four target points are respectively arranged on the front bracket and the rear bracket, and every three target points are not collinear; the distance between the front bracket and the rear bracket of the attitude adjusting platform is a constant value, a target 1 and a target 2 are attached to the side surface of the frame in the direction parallel to the ground track, and the distance between the two targets is L; four target points on the front bracket are J under the global coordinate systemi1(i ═ 1, 2, 3, 4), and the four target points on the rear carriage are Ji2(i is 1, 2, 3, 4), front and rear carriage circle center coordinates J51、J52Thereby determining the transformation relationship between the two local bracket coordinate systems and the global coordinate system asOqTOJ1OqTOJ2
Establishing a virtual pose-adjusting coordinate system Ot1-Xt1Yt1Zt1Origin of coordinates Ot1As the centre coordinate J of the bracket51、J52Midpoint of line, Xt1The axis points to the course of the section along the line connecting the centers of the circles, plane Ot1-Xt1Zt1Constant over-carriage local coordinate system OJ1-XJ1YJ1ZJ1Z of (A)J1Axes, i.e. constant over-coordinate system OJ1-XJ1YJ1ZJ1At the lower d point (0, 0, R), then Yt1Axis may be defined by vector
Figure BDA0002270175120000063
Obtaining of Zt1The axes are obtained from the right hand rule. Finally, the conversion relation between the virtual pose adjusting coordinate system and the assembly coordinate system is obtained: rotation transformation matrixORt1Offset amount ofOTt1
5. Selecting the origin of the center of the bracket as an attitude adjusting control point A, B, and setting A under an assembly coordinate systemO=(Xao,Yao,Zao),BO=(Xbo,Ybo,Zbo) In the attitude-adjusting coordinate system At1=(Xat1,Yat1,Zat1),Bt1=(Xbt1,Ybt1,Zbt1). The coordinate system establishment and transformation relation are calculated as follows:
taking the section 1 as an example, the section 1 is clamped on the bracket, which is equivalent to that the local coordinate system of the butt joint surface of the section is interconnected with the attitude adjusting coordinate system rigid body, and in the butt joint process, the angle of the local coordinate system rotating around the assembly coordinate system is the angle of the attitude adjusting coordinate system rotating around the assembly coordinate system.
In the process of rotating and adjusting the posture, firstly rotating around the Y axis of an assembly coordinate system, wherein the rotating angle is alpha; rotating around the Z axis of the assembly coordinate system, wherein the rotating angle is beta; and finally, rotating around the X axis of the assembly coordinate system, wherein the rotating angle is gamma. The angles alpha, beta, gamma can be transformed by a rotation transformation matrixORO1And (4) obtaining.
In the assembled coordinate system, the coordinates of the control point A, B are changed to obtain the amount of angular rotation. When rotating about the Y axis At1`=(Xat1,Yat1,Ltanα/2+Zat1),Bt1`=(Xbt1,Ybt1,-Ltanα/2+Zbt1) (ii) a While rotating about the Z axis At1``=(Xat1,Ltanβ/2+Yat1,Ltanα/2+Zat1),Bt1``=(Xbt1,-Ltanβ/2+Ybt1,-Ltanα/2+Zbt1) (ii) a And finally, rolling around the X axis and rotating the gamma angle.
After the rotation posture adjustment is finished, according toOTO1The amount of translation is determined, at which time pose point A, B is simultaneously moved in synchronization with the amount of translation.
The carrier rocket is butted in a pin hole positioning mode, a butted object is in a large-size circular cylinder section structure, and the cylinder section can deform due to self weight; at the moment, the deformation amount needs to be predicted, and if the deformation amount is within the tolerance range, the docking task is continuously executed; and if the deformation exceeds the tolerance range, compensating the deformation deviation and finishing the butt joint.
The above amount of exercise (α, β, γ, x)T,yT,zT) I.e. the amount of adjustment required to control the system.
The method of the invention is described in detail below with reference to the accompanying drawings:
the first embodiment is as follows: the embodiment is described with reference to fig. 1, fig. 2 and fig. 3, and the invention aims at establishing a coordinate system and solving control quantity for assembling a carrier rocket section under the guidance of vision measurement, wherein the coordinate system is established by taking a reference target as a base point.
Step 1, arranging an automatic assembly and docking system guided by vision measurement as shown in figure 1, placing a calibration plate in a docking azimuth of a carrier rocket, and selecting one point in the calibration plate as an origin O of a global coordinate systemqPerpendicular to the ground down by YqThe parallel pointing course of the shaft and the butt joint platform track is XqAxis, ZqThe axial direction is determined by the right hand rule.
Step 2. according to the direct Linear method (DLT) formula:
Figure BDA0002270175120000081
(Xpi,Ypi,Zpi1) is a known coordinate point i, (u) on the calibration platei,viAnd 1) obtaining a coordinate point conversion matrix M for a known coordinate point i of the camera image.
Step 3, as can be known from a linear camera model, in the step 2 of the first embodiment, the matrix M in the equation contains 11 unknowns of the internal and external parameters of the camera, and can be solved only by requiring more than 6 known points, while the known number on the calibration plate is far greater than the number, and the solution error is reduced by adopting a least square method.
And 4, after the calibration of the internal and external parameters of the camera is finished, removing the calibration plate, and placing the calibration plate to prevent the automatic butt joint of the subsequent sections.
Step 5, establishing a local butt joint reference system O of the sections on the butt joint planes of the butt joint sections 1 and 2 of the carrier rocket1-X1Y1Z1、O2-X2Y2Z2(ii) a As shown in FIG. 2, the origin of the reference system is located at the center point of the respective docking planes, the X-axis direction points to the heading along the respective axes, the Y-axis direction points to quadrant I, and the Z-axis direction is determined by the right-hand rule.
And 6, characteristic points of the section butt joint planes are positioning pin holes on the circumference, as shown in fig. 2, the characteristic points are respectively positioned at a measuring point I, a measuring point II, a measuring point III and a measuring point IV, a target is required to be installed at the measuring point through a switching tool during calibration, and the position coordinates of the target are obtained by depending on the position precision of a positioning pin shaft.
Step 7, taking the section 1 butt joint plane as an example, in a global coordinate system Oq-XqYqZqNext, the coordinate values of the four target measurement points in the global coordinate system can be directly obtained after the calibration of the internal and external parameters of the camera, and are marked as Ci(i=1,2,3,4),Ci=(Xqi,Yqi,Zqi)。
Step 8, arbitrarily selecting three points from the measuring points, respectively substituting three point values into formula (X) with the radius R of the section butt joint plane as a known valueqi-XOq1)2+(Yqi-YOq1)2+(Zqi-ZOq1)2=R2Obtaining Oq1=(XOq1,YOq1,ZOq1)。
Step 9, arbitrarily taking three points C from the measuring points4 3In 4 cases, four possible values with slight deviations at the center of the butting plane are obtained, and the four values are obtained according to the formula
Figure BDA0002270175120000091
The center of four values is obtained as the center point Oq1Thereby reducing the error.
Step 10, in a local coordinate system O1-X1Y1Z1Next, the four target points are obtained by the size and position values of the pin shaft and are marked as Si(i=1,2,3,4),Si=(0,Y1i,Z1i)。
Step 11, selecting three points from the formula (Y)1i-YO11)2+(Z1i-ZO11)2=R2Obtaining O11=(0,YO11,ZO11). Similarly, the central point O can be known by the permutation and combination11May have C4 34 values according to formula
Figure BDA0002270175120000092
Figure BDA0002270175120000093
Finding the center of the four values as the center point O11Thereby reducing the error.
Step 12, obtaining the circle center coordinate O under the global coordinate system of the butt joint plane of the section 2 in the same wayq2Circle center coordinate O in local coordinate system22
Step 13, establishing an assembly coordinate system O-XYZ with the butt joint of the sections, wherein the origin of coordinates O is positioned at Oq1、Oq2The directions of the coordinate axes of the assembly coordinate system are consistent with the global coordinate system.
Step 14, the coordinate of the local coordinate system origin of the segment butt joint plane under the global coordinate is known as Oq1、Oq2The origin of the assembly coordinate system under the global coordinate system is Oq=(Oq1+Oq2)/2。
Step 15, therefore, the translation conversion relation exists between the assembly coordinate system and the global coordinate systemOTOq
Figure BDA0002270175120000094
Step 16, according to the conversion relationOTOqThe coordinate value C of the target point and the central point of the segment butt joint plane under the assembly coordinate system can be obtainedOi、OO1
Step 17, coordinate point COiAnd Si、OO1And O11For different coordinate systems O-XYZ and O1-X1Y1Z1The same spatial point below, and the coordinate values are known. Local coordinate system O1-X1Y1Z1The following conversion relation exists between the assembly coordinate system O-XYZ:
Figure BDA0002270175120000101
the second embodiment is as follows: the present embodiment is described with reference to fig. 1 and 5, and the present invention is directed to solving the relationship for the transformation of the local coordinate system and the assembly coordinate system of the launch vehicle segment guided by vision measurement.
Step 1, the conversion relation between the local coordinate system and the assembly coordinate system can be as follows:
Figure BDA0002270175120000102
step 2. for obtaining the local coordinate system O1-X1Y1Z1And a deflection relation matrix between the assembly coordinate system O-XYZ, firstly solving the center of a known point:
Figure BDA0002270175120000103
step 3, passing through formula Cmi=COi-m,OmO1=OO1-m,Smi=Si-n,Om11=O11N, translating the two coordinate systems to the central point, in which caseOTO1Is removed and the demanded solution isORO1
Step 4. rotating the matrixORO1The available formula is determined in the manner of fig. 5:
Figure BDA0002270175120000104
step 5, adding Cmi=COi-m,OmO1=OO1-m,Smi=Si-n,Om11=O11-n substituting for formula:
Figure BDA0002270175120000105
and 6, unfolding to obtain an equation set:
Figure BDA0002270175120000111
and 7, substituting the following formula into the formula:
Figure BDA0002270175120000112
step 8, setting tan (alpha/2) ═ X1、tan(β/2)=X2、tan(γ/2)=X3(ii) a Finally, the unknown number X can be obtained from step 4 of the second embodiment1、X2、X3The non-linear equation of (a):
Figure BDA0002270175120000113
step 9, let X ═ X (X)1,X2,X3),F=(f1,f2,f3) And solving a nonlinear equation system.
X(k+1)=X(k)-F(X(k))-1F(X(k))
X(k+1)=X(k)+ΔX(k)
Step 10. the Jacobian matrix of the nonlinear equation set can be obtained by the following formula:
Figure BDA0002270175120000114
step 11, a Newton iteration method is adopted to solve a rotation transformation matrixORO1And obtaining the optimal solution by adopting a least square method. Will be provided withORO1Substituting into the conversion relation between the local coordinate system and the assembly coordinate system to obtain the final productOTO1
Step 12, the local coordinate system O of the section 2 can be obtained in the same way2-X2Y2Z2Rotation matrix with assembly coordinate system O-XYZORO2And translation matrixOTO2
The third concrete implementation mode: the embodiment is described with reference to fig. 4, and the invention provides a specific implementation method for the calibration establishment of the virtual attitude adjustment coordinate system of the automatic docking platform of the carrier rocket section under the guidance of vision measurement.
Step 1, establishing a local coordinate system O of a front bracketJ1-XJ1YJ1ZJ1Local coordinate system O of rear bracketJ2-XJ2YJ2ZJ2The directions of coordinate axes of the two coordinate systems are consistent with the direction of the global coordinate system, and the origin of coordinates OJ1、OJ2Are respectively positioned at the circle center of the bracket.
And 2, respectively arranging four target points on the front bracket and the rear bracket of the trolley, wherein every three target points are not collinear.
And 3, the shortest straight line distance between the front and rear brackets of the attitude adjusting platform is a constant value, the targets 1 and 2 are attached to the side surface of the frame in the direction parallel to the ground track, and the distance between the two targets is L.
Step 4, the coordinate values of the four target points on the front bracket under the global coordinate system can be obtained from the first step 2 of the embodiment as Ji1(i is 1, 2, 3, 4), and the coordinate values of the four target points on the rear carriage are Ji2(i=1,2,3,4)。
Step 5, taking three points from the measuring points as an example of the former bracket, taking the radius r of the vehicle lifting bracket as a known value, and respectively substituting the three points into the formula (X)Ji-XOJ1)2+(YJi-YOJ1)2+(ZJi-ZOJ1)2=r2Obtaining OJ1=(XOJ1,YOJ1,ZOJ1)。
Step 6, follow measurementArbitrarily selecting three points C from the points4 3In 4 cases, four values with small deviation can be obtained from the center of the butt joint plane, and the four values are obtained according to the formula
Figure BDA0002270175120000121
The center of four values is obtained as the center point OJ1Thereby reducing the error.
Step 7, recording the coordinates of the central points of the front bracket and the rear bracket as J51、J52Thereby determining the transformation relationship between the two local bracket coordinate systems and the global coordinate system asOqTOJ1OqTOJ2
8. Establishing a virtual pose-adjusting coordinate system Ot1-Xt1Yt1Zt1Origin of coordinates Ot1As the centre coordinate J of the bracket51、J52The midpoint of the connecting line, i.e. Ot1=(J51+J52)/2。
Step 9.Xt1The shaft points to the course of the section along the connecting line of the circle centers
Figure BDA0002270175120000131
The unit direction vector of the axis in the global coordinate system is obtained.
Step 10, plane Ot1-Xt1Zt1Constant over-carriage local coordinate system OJ1-XJ1YJ1ZJ1Z of (A)J1Axes, i.e. constant over-coordinate system OJ1-XJ1YJ1ZJ1Lower d point (0, 0, R), then
Figure BDA0002270175120000132
Step 11.Yt1Axis may be defined by vector
Figure BDA0002270175120000133
Obtaining of Zt1Shaft rule by right hand
Figure BDA0002270175120000134
And (4) obtaining.
Step 12Virtual pose adjustment coordinate system Ot1-Xt1Yt1Zt1And a global coordinate system Oq-XqYqZqThe conversion relationship can be obtained by the formula in step 1 of the second embodiment.
Step 13. the transformation relation between the global coordinate system and the assembly coordinate system is obtained by the first embodiment, so that the rotation transformation matrix of the virtual pose adjusting coordinate system and the assembly coordinate system can be finally obtainedORt1Offset amount ofOTt1
The fourth concrete implementation mode: the embodiment is described with reference to fig. 4, 5 and 6, and the invention aims at the control quantity of each attitude adjusting control point in an assembly coordinate system for completing the butt joint of the sections of the automatic assembly butt joint platform of the carrier rocket section under the guidance of vision measurement.
Step 1, taking the assembly butt joint platform of the section 1 as an example, selecting the origin of the center of the bracket as an attitude adjusting control point A, B, and A in an assembly coordinate systemO=(Xao,Yao,Zao),BO=(Xbo,Ybo,Zbo) In the attitude-adjusting coordinate system At1=(Xat1,Yat1,Zat1),Bt1=(Xbt1,Ybt1,Zbt1)。
Step 2, the target coordinate system of the butt joint plane of the section 1 is an assembly coordinate system, and the required motion corner and translation amount can be determined by the local coordinate of the butt joint plane when the local coordinate of the butt joint plane is superposed with the target coordinate systemORO1OTO1Is obtained in which
Figure BDA0002270175120000135
OTO1I.e. the amount of translation.
Step 3, clamping the section 1 on a vehicle lifting bracket, and interconnecting a local coordinate system and a posture adjusting coordinate system through a clamping section butt joint surface rigid body; and (3) the continuity between each point on the rigid body, and the rotating angle of the virtual attitude adjusting coordinate system around the assembly coordinate system is the rotating angle of the local coordinate system around the assembly coordinate system.
Step 4, as can be seen from fig. 5, in the rotating and posture-adjusting process, the rotating shaft rotates around the Y axis of the assembly coordinate system, and the rotating angle is alpha; rotating around the Z axis of the assembly coordinate system, wherein the rotating angle is beta; and finally, rotating around the X axis of the assembly coordinate system, wherein the rotating angle is gamma.
And 5, under an assembly coordinate system, in order to obtain the angle rotation quantity, the coordinates of the control point A, B are changed. When rotating about the Y axis At1`=(Xat1,Yat1,Ltanα/2+Zat1),Bt1`=(Xbt1,Ybt1,-Ltanα/2+Zbt1) (ii) a While rotating about the Z axis At1``=(Xat1,Ltanβ/2+Yat1,Ltanα/2+Zat1),Bt1``=(Xbt1,-Ltanβ/2+Ybt1,-Ltanα/2+Zbt1) (ii) a And finally, rolling around the X axis and rotating the gamma angle.
Step 6, after the rotation posture adjustment is finished, according toOTO1And determining the translation amount, wherein the attitude adjusting points A, B synchronously move to realize the translation movement.
And 7, in order to realize butt joint, the local coordinate system of the section 2 also uses the assembly coordinate system as a target coordinate system, and the posture adjustment is realized through the steps in the same way.
And 8, the section 2 completes the rotation posture adjustment and the translation movement of the Y axis and the Z axis, the movement of the X axis is in a pause state, and at the moment, a Monte Carlo simulation method is needed to predict the assembly errors of most sections.
And 9, establishing a CAD model of the assembly section through VSA, and marking the tolerance of the section and the pin hole on the model.
And 10, determining the sequence of rotation and translation transformation of the sections 1 and 2 to the target coordinate system.
And 11, determining the quality of the sections, the assembly gaps among the sections and the matching gaps of the corresponding positioning pin holes.
And 12, simulating the assembling process, and recording and outputting the deformation of the pin hole. And if the deviation amount is within the tolerance allowable range, executing X-axis movement and finishing assembly.
And step 13, distributing the deviation amount to each motion axis according to the fourth step 5 of the specific implementation mode if the deviation amount is not within the tolerance range, performing error compensation, executing X-axis motion, and finishing assembly.
And 14, before the X-axis movement is executed and the assembly is completed, taking down the target and the switching tool to prevent the blocking sections from being in butt joint assembly, and finally realizing the X-axis translation movement to complete the butt joint.

Claims (7)

1. A major segment attitude adjusting and docking method of a carrier rocket based on binocular vision measurement is characterized by comprising the following steps: the method comprises the following steps:
step one, establishing a global coordinate system Oq-XqYqZq
Step two, establishing a local coordinate system O of two butt joint sections1-X1Y1Z1、O2-X2Y2Z2Wherein: the two local coordinate systems O1-X1Y1Z1、O2-X2Y2Z2O of (A) to (B)1、O2The points are respectively located at the circle center of the front and rear section butt joint planes, Y1、Y2Pointing to quadrant I, X1、X2Respectively pointing to the course of the carrier rocket along the central axis of each section, Z1、Z2The direction is determined according to the right-hand rule; the characteristic points of the butt joint planes of the two sections are positioning pin holes on the circumference and are respectively positioned at a measuring point I, a measuring point II, a measuring point III and a measuring point IV, targets are installed at the four measuring points through a switching tool during calibration, and the circle center coordinates of the butt joint planes of the two sections under the global coordinate system are Oq1And Oq2And the center coordinates in the local coordinate system are O11And O22Wherein:
said O isq1And O11The calculation method comprises the following steps:
(1) in a global coordinate system Oq-XqYqZqThen, the coordinate values of the four target measurement points are marked as Ci,Ci=(Xqi,Yqi,Zqi) Wherein i is (1, 2, 3, 4), three points are selected from the group, and the formula (X) is substituted respectivelyqi-XOq1)2+(Yqi-YOq1)2+(Zqi-ZOq1)2=R2Wherein R is the radius of the section butt joint plane, and O is obtained by calculationq1=(XOq1,YOq1,ZOq1) (ii) a Exhaust C4 3Averaging after combination to obtain Oq1
(2) In a local coordinate system O1-X1Y1Z1Next, the coordinate values of the four target measurement points are denoted as Si,Si=(0,Y1i,Z1i) Wherein i is (1, 2, 3, 4), three points are selected from the group, and the formula (Y) is substituted1i-YO11)2+(Z1i-ZO11)2=R2Calculating to obtain O11=(0,YO11,ZO11) (ii) a Exhaust C4 3Averaging after combination to obtain O11
Step three, establishing an assembly coordinate system O-XYZ, and respectively determining two local coordinate systems O1-X1Y1Z1And O2-X2Y2Z2A conversion relation matrix between the assembly coordinate system and O-XYZ;
step four, establishing a virtual pose adjusting coordinate system Ot1-Xt1Yt1Zt1
And step five, determining the control quantity of each attitude adjusting control point in the assembly coordinate system.
2. The binocular vision measurement-based posture-adjusting docking method for the large section of the launch vehicle of claim 1, wherein: step one the global coordinate system Oq-XqYqZqY of (A) to (B)qThe positive direction of the axis is vertical to the ground and faces downwards, XqAxis parallel to the docking platform track, ZqThe axial direction is determined by the right-hand rule, origin of coordinates OqAnd the position relation between the global coordinate system and the camera coordinate system is obtained by a linear calibration method.
3. The binocular vision measurement-based launch vehicle of claim 1The section posture adjusting butt joint method is characterized in that: thirdly, the directions of all axes of the assembly coordinate system O-XYZ are the same as the global coordinate system, and the origin of coordinates O is positioned at Oq1、Oq2The assembly coordinate system and the global coordinate system have the following translation conversion relation in the middle point of the connecting line:
Figure FDA0003139902210000021
4. the binocular vision measurement-based posture-adjusting docking method for the large section of the launch vehicle of claim 3, wherein: said local coordinate system O1-X1Y1Z1The conversion relation matrix with the assembly coordinate system O-XYZ is determined according to the following method:
(1) according toOTOqCalculating to obtain coordinate values C of target points and central points of the segment butt joint planes in an assembly coordinate systemOi、OO1
(2) Establishing a local coordinate system O1-X1Y1Z1And the conversion relation with an assembly coordinate system O-XYZ is as follows:
Figure FDA0003139902210000022
wherein:ORO1in order to rotate the transformation matrix, the transformation matrix is rotated,OTO1is a deflection relation matrix;
(3) the center point (m, n) is calculated as follows:
Figure FDA0003139902210000023
Figure FDA0003139902210000024
(4) passing formula Cmi=COi-m,OmO1=OO1-m;Smi=Si-n,Om11=O11N, translating the two coordinate systems to the central point, and then solving by adopting a Newton iteration methodORO1And then finally findOTO1
5. The binocular vision measurement-based posture-adjusting docking method for the large section of the launch vehicle of claim 4, wherein: step four, the virtual pose adjusting coordinate system Ot1-Xt1Yt1Zt1The establishing method comprises the following steps:
(1) establishing a local coordinate system O of the front bracketJ1-XJ1YJ1ZJ1And a rear bracket local coordinate system OJ2-XJ2YJ2ZJ2The directions of coordinate axes of the two coordinate systems are consistent with the direction of the global coordinate system, and the origin of coordinates OJ1、OJ2Are respectively positioned at the circle center of the bracket;
(2) four target points are respectively arranged on the front bracket and the rear bracket, and every three target points are not collinear; the shortest straight line distance between the front bracket and the rear bracket of the attitude adjusting platform is a constant value, a first target and a second target are attached to the side surface of the frame in the direction parallel to the ground track, and the distance between the two targets is L; four target points on the front bracket are J under the global coordinate systemi1The four target points on the rear bracket are Ji2I is (1, 2, 3, 4), and coordinates J of center of circle of front and rear brackets are obtained51And J52Further determine the transformation relationship between the two local bracket coordinate systems and the global coordinate systemOqTOJ1AndOqTOJ2
(3) establishing a virtual pose-adjusting coordinate system Ot1-Xt1Yt1Zt1Origin of coordinates Ot1Is a coordinate J of the circle center of the front bracket and the rear bracket51、J52Midpoint of line, Xt1The shaft points to the course of the section along the connecting line of the circle centers, Yt1Axial direction vector
Figure FDA0003139902210000031
Obtaining, wherein:
Figure FDA0003139902210000032
Zt1the axis is obtained by the right hand rule;
(4) obtaining a rotation transformation matrix in the transformation relation between the virtual pose coordinate system and the assembly coordinate system by using the transformation relation between the global coordinate system and the assembly coordinate systemORt1And offsetOTt1
6. The binocular vision measurement-based posture-adjusting docking method for the large section of the launch vehicle of claim 5, wherein: fifthly, the step of determining the control quantity of each attitude adjusting control point in the assembly coordinate system comprises the following steps:
(1) selecting the central origin of the front bracket and the rear bracket of the first section as attitude adjusting control points A and B, and A is an assembly coordinate systemO=(Xao,Yao,Zao),BO=(Xbo,Ybo,Zbo) In the attitude-adjusting coordinate system At1=(Xat1,Yat1,Zat1),Bt1=(Xbt1,Ybt1,Zbt1);
(2) In the process of rotating and adjusting the posture, firstly rotating around the Y axis of an assembly coordinate system, wherein the rotating angle is alpha; rotating around the Z axis of the assembly coordinate system, wherein the rotating angle is beta; finally rotating around the X axis of the assembly coordinate system, wherein the rotation angle is gamma, and alpha, beta and gamma are transformed by a rotation transformation matrixORO1Obtaining; when rotated about the Y-axis, the coordinates of control point A, B change to: a. thet1`=(Xat1,Yat1,Ltanα/2+Zat1),Bt1`=(Xbt1,Ybt1,-Ltanα/2+Zbt1) (ii) a When rotated about the Z-axis, the coordinates of control point A, B change as: a. thet1``=(Xat1,Ltanβ/2+Yat1,Ltanα/2+Zat1),Bt1``=(Xbt1,-Ltanβ/2+Ybt1,-Ltanα/2+Zbt1);
(3) After the rotation posture adjustment is finished, according toOTO1Determining the amount of translation (x)T,yT,zT) At this time, the attitude adjusting point A, B synchronously moves the translation amount at the same time;
(4) the second section completes the rotation posture adjustment and the translation motion of the Y axis and the Z axis in the same way, the motion of the X axis is in a pause state, the deformation is predicted by adopting a Monte Carlo simulation method, and if the deformation is within the tolerance range, the butt joint task is continuously executed; and if the deformation exceeds the tolerance range, the butt joint is completed after the deformation deviation is compensated.
7. The binocular vision measurement-based posture-adjusting docking method for the large section of the launch vehicle of claim 6, wherein: the method for predicting the deformation by adopting the Monte Carlo simulation method comprises the following steps:
(1) establishing a CAD model of the assembly section through VSA, and marking the tolerance of the section and the pin hole on the model;
(2) determining the sequence of the rotation and translation transformation of the first section and the second section to the target coordinate system;
(3) determining the quality of the sections, the assembly clearance among the sections and the matching clearance of the corresponding positioning pin holes;
(4) simulating the assembling process, and recording and outputting the deformation of the pin hole;
(5) judging whether the deformation at the pin hole is within the tolerance allowable range: if so, executing X-axis motion to finish assembly; if not, distributing the deformation to each motion axis for error compensation, and then executing X-axis motion to complete assembly.
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