CN105547259B - Space Large Deployable flexible body mode measuring method based on video acquisition - Google Patents

Space Large Deployable flexible body mode measuring method based on video acquisition Download PDF

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CN105547259B
CN105547259B CN201510947444.0A CN201510947444A CN105547259B CN 105547259 B CN105547259 B CN 105547259B CN 201510947444 A CN201510947444 A CN 201510947444A CN 105547259 B CN105547259 B CN 105547259B
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flexible body
characteristic point
image plane
mrow
space
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CN105547259A (en
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吕旺
洪振强
王田野
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Shanghai Institute of Satellite Engineering
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Shanghai Institute of Satellite Engineering
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C11/00—Photogrammetry or videogrammetry, e.g. stereogrammetry; Photographic surveying
    • G01C11/04—Interpretation of pictures

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Abstract

The invention provides a kind of space Large Deployable flexible body mode measuring method based on video acquisition, the mode measuring method of distinguished point based video acquisition, including：Video acquisition is carried out to some characteristic points on flexible body；By obtaining actual displacement of the characteristic point in object space to Computer Vision；The large-scale flexible body mode principal mode that extraction finite element analysis software obtains；Flexible body modal coordinate is calculated by characteristic point actual displacement and mode principal mode.The present invention does not increase extra electric wire and sensor mass to flexible body, does not influence the architecture quality characteristic of flexible body, can more accurately obtain the modal coordinate of flexible body on in-orbit spacecraft by the method for video acquisition.

Description

Space Large Deployable flexible body mode measuring method based on video acquisition
Technical field
, can in particular it relates to which the space based on video acquisition is large-scale the present invention relates to the technology of Dynamics of spacecraft Deploy flexible body mode measuring method, in particular for the in-orbit mode to the spacecraft with Large Deployable flexible body The method that coordinate measures calculating.
Background technology
Modern space aircraft configurations are complicated, in-orbit often comprising the large-scale flexible body such as large-scale solar array and large-scale antenna The effect for being vulnerable to interference and control during flight evokes structural vibration, gently then influences control accuracy, and heavy then Risk health behavior is stable Property even aircraft security.To obtain space Large Deployable flexible body vibration parameters, it is necessary to modal coordinate to flexible vibration Measure, for assessing and the in-orbit dynamics environment of room for improvement aircraft.
Modal coordinate characterizes each Mode Shape ratio shared in body vibration, and in general is obtained by dynamics simulation , it changes is interacted by coefficient of coup matrix and aircraft body.Obviously, simulation model is difficult to react actual work completely Every influence factor in journey.
Currently without the explanation or report for finding technology similar to the present invention, money similar both at home and abroad is also not yet collected into Material.
The content of the invention
For in the prior art the defects of, open up it is an object of the invention to provide a kind of space based on video acquisition is large-scale Open flexible body mode measuring method.
According to a kind of space Large Deployable flexible body mode measuring method based on video acquisition provided by the invention, bag Include：
Step 1：Characteristic point sport video carries out barycenter extraction on the flexible body collected to camera, obtains characteristic point and exists The displacement of camera image plane；
Step 2：The actual displacement of characteristic point in space is obtained in the displacement of camera image plane by characteristic point, is then obtained Projection of the actual displacement of characteristic point in space in image plane；
Step 3：The FEM model of flexible body is analyzed, extraction obtains the vibration shape of flexible body, and binding characteristic point is in flexible body Node location corresponding to upper, component of the vibration shape at characteristic point is obtained, and by component projection of the vibration shape at characteristic point as flat On face, projection of component of the vibration shape at characteristic point in image plane is obtained；
Step 4：According to the actual displacement of the characteristic point in space projecting in image plane, the vibration shape in feature Projection of the component in image plane at point, obtains the modal coordinate of flexible body.
Preferably, the step 4 comprises the following steps：
In image plane, the actual displacement of the characteristic point in space in image plane projection coordinate value divided by it is described Projection coordinate value of component of the vibration shape at characteristic point in image plane, obtains the modal coordinate of flexible body.
Preferably, the step 1 includes：
Characteristic point is identified by LED on flexible body；
By camera alignment characteristicses point, ensure that characteristic point is always situated in camera fields of view in flexible body vibration processes；
Give flexible body one incentive action, characteristic point sport video after excitation applies under cameras record；
Video is handled frame by frame, obtains characteristic point facula mass center in the movement locus of camera image plane as the reality Border displacement.
Preferably, the step 2 includes：
The actual displacement of characteristic point in space is obtained according to the formula of being calculated as below：
Wherein, ureal(t) actual displacement of characteristic point in space, u are representedpic(t) represent characteristic point in camera image plane Displacement, t represents time variable, and θ represents the angle of camera perspective direction of vibration and flexible body direction of vibration.
Preferably,
uk(t)=φkη(t)
Wherein, uk(t) actual displacement of node k on flexible body, φ are representedkRepresent component battle array of each first order mode in node k, η (t) modal coordinate array is represented.
Compared with prior art, the present invention has following beneficial effect：
1st, in order to accurately obtain the modal coordinate of the large-scale flexible body of in-orbit spacecraft, the present invention is by large-scale flexibility Characteristic point carries out video acquisition on body, then resolves through image procossing and geometrical relationship to obtain the actual displacement of characteristic point, is combined with Component of the Mode Shape that limit meta software is analyzed to obtain in characteristic point, is finally calculated space Large Deployable flexible body Modal coordinate.
2nd, the present invention does not increase extra electric wire and sensor mass, not shadow by the method for video acquisition to flexible body The architecture quality characteristic of flexible body is rung, can more accurately obtain the modal coordinate of flexible body on in-orbit spacecraft.
Brief description of the drawings
The detailed description made by reading with reference to the following drawings to non-limiting example, further feature of the invention, Objects and advantages will become more apparent upon：
Fig. 1 is the principle schematic of the space Large Deployable flexible body mode measuring method based on video acquisition.
Fig. 2 is camera installation site and characteristic point position geometrical relationship schematic diagram.
Embodiment
With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that the ordinary skill to this area For personnel, without departing from the inventive concept of the premise, some changes and improvements can also be made.These belong to the present invention Protection domain.
The present invention provides a kind of space Large Deployable flexible body mode measuring method based on video acquisition, is related to space flight Device dynamic and control field, it is the mode measuring method of distinguished point based video acquisition.Including：To on flexible body Some characteristic points carry out video acquisition；By obtaining actual displacement of the characteristic point in object space to Computer Vision；Extraction The large-scale flexible body mode principal mode that finite element analysis software obtains；Calculated by characteristic point actual displacement and mode principal mode Flexible body modal coordinate.
According to a kind of space Large Deployable flexible body mode measuring method based on video acquisition provided by the invention, bag Include：
Step 1：Characteristic point sport video carries out barycenter extraction on the flexible body collected to camera, obtains characteristic point and exists The displacement of camera image plane；
Step 2：The actual displacement of characteristic point in space is obtained in the displacement of camera image plane by characteristic point, is then obtained Projection of the actual displacement of characteristic point in space in image plane；
Step 3：The FEM model of flexible body is analyzed, extraction obtains the vibration shape of flexible body, and binding characteristic point is in flexible body Node location corresponding to upper, component of the vibration shape at characteristic point is obtained, and by component projection of the vibration shape at characteristic point as flat On face, projection of component of the vibration shape at characteristic point in image plane is obtained；
Step 4：According to the actual displacement of the characteristic point in space projecting in image plane, the vibration shape in feature Projection of the component in image plane at point, obtains the modal coordinate of flexible body.
Preferably, the step 4 comprises the following steps：
In image plane, the actual displacement of the characteristic point in space in image plane projection coordinate value divided by it is described Projection coordinate value of component of the vibration shape at characteristic point in image plane, obtains the modal coordinate of flexible body.
Preferably, the step 1 includes：
Characteristic point is identified by LED on flexible body；
By camera alignment characteristicses point, ensure that characteristic point is always situated in camera fields of view in flexible body vibration processes；
Give flexible body one incentive action, characteristic point sport video after excitation applies under cameras record；
Video is handled frame by frame, obtains characteristic point facula mass center in the movement locus of camera image plane as the reality Border displacement.
Preferably, the step 2 includes：
The actual displacement of characteristic point in space is obtained according to the formula of being calculated as below：
Wherein, ureal(t) actual displacement of characteristic point in space, u are representedpic(t) represent characteristic point in camera image plane Displacement, t represents time variable, and θ represents the angle of camera perspective direction of vibration and flexible body direction of vibration.
Preferably,
uk(t)=φkη(t)
Wherein, uk(t) actual displacement of node k on flexible body, φ are representedkRepresent component battle array of each first order mode in node k, η (t) modal coordinate array is represented.
More specifically, include 4 parts see Fig. 1, the implementation content of method provided by the invention, be respectively：It is determined that Movement locus of the characteristic point in camera image plane on flexible body；Determine the actual displacement of characteristic point in space on flexible body；Really Determine component of the flexible body principal mode in characteristic point；Determine modal coordinate corresponding to flexible body principal mode.With reference to " satellite body The experiment of+solar battery array " air floating platform is illustrated four parts to more than.
1. determine that characteristic point is in the movement locus of camera image plane on flexible body
Characteristic point can be identified by high-brightness LED on flexible body, and obvious bright spot is shown as in camera fields of view. In experiment, by camera alignment characteristicses point, ensure in flexible body vibration processes that characteristic point is always situated in the visual field within.To system one Incentive action, characteristic point sport video after excitation applies under cameras record, collection frame frequency is 25Hz.Video is located frame by frame Reason, obtains the movement locus of characteristic point hot spot center of gravity or barycenter in camera image plane.
2. determine the actual displacement of characteristic point in space on flexible body
The actual displacement of characteristic point in space is obtained according to camera focus and characteristic point thing square.In assembly air floating platform In experiment.From camera imaging principle, looked over from camera direction of visual lines, the camera apparent motion displacement of characteristic point is image plane N times (N is object distance than focal length) of upper subpoint displacement.The camera apparent displacement u of characteristic pointpicAnd actual displacement u (t)real(t) Relation is
Wherein θ is the angle of camera perspective direction of vibration and vertical windsurfing direction of vibration.upic(t) can by image procossing To obtain, so as to which characteristic point actual displacement u be calculatedreal(t)。
3. determine component of the flexible body principal mode in characteristic point
The vibration shape is the shape of certain rank vibration, and after flexible body gridding, each first order mode is solid in the component of each node Fixed.Each first order mode of flexible body can be obtained by finite element analysis software.In air floating platform experiment, principal mode is outside single order Bending vibration type.
4. determine modal coordinate corresponding to flexible body principal mode
Theoretical according to vibration mechanics, the vibration displacement of certain quality point is represented by flexible body
uk(t)=φkη(t)
In formula, uk(t) actual displacement for being node k, φkIt is each first order mode in the component battle array of k points, η (t) is modal coordinate Array.U can be measured by preceding two partsk(t), φ is obtained by the way that third portion is extractablek, so as to solve modal coordinate
If L first order modes, φ before takingkFor 3 × L matrixes, η (t) is the array of L × 1.So as to realize by characteristic point Video acquisition measurement calculates flexible body modal coordinate.
The video of characteristic point motion, calculates characteristic point actual displacement on the present invention collection large-scale flexible body of spacecraft, The Mode Shape obtained with reference to finite element analysis software, is calculated modal coordinate, and flexibility is provided for vehicle dynamics model The modal vibration information of body.
The specific embodiment of the present invention is described above.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make a variety of changes or change within the scope of the claims, this not shadow Ring the substantive content of the present invention.In the case where not conflicting, the feature in embodiments herein and embodiment can any phase Mutually combination.

Claims (3)

  1. A kind of 1. space Large Deployable flexible body mode measuring method based on video acquisition, it is characterised in that including：
    Step 1：Characteristic point sport video carries out barycenter extraction on the flexible body collected to camera, obtains characteristic point in camera The displacement of image plane；
    Step 2：The actual displacement of characteristic point in space is obtained in the displacement of camera image plane by characteristic point, then obtains feature Projection of the actual displacement in image plane of point in space；
    Step 3：The FEM model of flexible body is analyzed, extraction obtains the vibration shape of flexible body, and binding characteristic point is right on flexible body The node location answered, component of the vibration shape at characteristic point is obtained, and by component projection of the vibration shape at characteristic point in image plane, Obtain projection of component of the vibration shape at characteristic point in image plane；
    Step 4：According to the actual displacement of the characteristic point in space projecting in image plane, the vibration shape at characteristic point Projection of the component in image plane, obtain the modal coordinate of flexible body；
    The step 2 includes：
    The actual displacement of characteristic point in space is obtained according to the formula of being calculated as below：
    <mrow> <msub> <mi>u</mi> <mrow> <mi>r</mi> <mi>e</mi> <mi>a</mi> <mi>l</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <mrow> <msub> <mi>u</mi> <mrow> <mi>p</mi> <mi>i</mi> <mi>c</mi> </mrow> </msub> <mrow> <mo>(</mo> <mi>t</mi> <mo>)</mo> </mrow> </mrow> <mrow> <mi>c</mi> <mi>o</mi> <mi>s</mi> <mi>&amp;theta;</mi> </mrow> </mfrac> </mrow>
    Wherein, ureal(t) actual displacement of characteristic point in space, u are representedpic(t) represent characteristic point in the position of camera image plane Move, t represents time variable, and θ represents the angle of camera perspective direction of vibration and flexible body direction of vibration；
    The step 4 comprises the following steps：
    In image plane, projection coordinate value divided by the vibration shape of the actual displacement of the characteristic point in space in image plane Projection coordinate value of the component in image plane at characteristic point, obtains the modal coordinate of flexible body.
  2. 2. the space Large Deployable flexible body mode measuring method according to claim 1 based on video acquisition, it is special Sign is that the step 1 includes：
    Characteristic point is identified by LED on flexible body；
    By camera alignment characteristicses point, ensure that characteristic point is always situated in camera fields of view in flexible body vibration processes；
    Give flexible body one incentive action, characteristic point sport video after excitation applies under cameras record；
    Video is handled frame by frame, obtains characteristic point facula mass center in the movement locus of camera image plane as the actual bit Move.
  3. 3. the space Large Deployable flexible body mode measuring method according to claim 1 based on video acquisition, it is special Sign is,
    uk(t)=φkη(t)
    Wherein, uk(t) actual displacement of node k on flexible body, φ are representedkRepresent component battle array of each first order mode in node k, η (t) Represent modal coordinate array.
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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101387546A (en) * 2008-10-29 2009-03-18 华南理工大学 Space sailboard bend and torsion low frequency mode detecting method and apparatus based on vision
CN102359779A (en) * 2011-07-28 2012-02-22 北京空间机电研究所 High stability multi-angle and multi-freedom satellite releasing and bearing apparatus of space remote sensing camera
CN104176272A (en) * 2014-08-06 2014-12-03 上海卫星工程研究所 Eight rod connection type non-contact satellite platform configuration
CN204695107U (en) * 2015-04-24 2015-10-07 西安羚控电子科技有限公司 Unmanned plane landing guidance device

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7800758B1 (en) * 1999-07-23 2010-09-21 Faro Laser Trackers, Llc Laser-based coordinate measuring device and laser-based method for measuring coordinates
US9269242B2 (en) * 2013-04-05 2016-02-23 Peter Lust, Jr. ASVVMS=Autonomous Space Vehicle Video Monitoring System

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101387546A (en) * 2008-10-29 2009-03-18 华南理工大学 Space sailboard bend and torsion low frequency mode detecting method and apparatus based on vision
CN102359779A (en) * 2011-07-28 2012-02-22 北京空间机电研究所 High stability multi-angle and multi-freedom satellite releasing and bearing apparatus of space remote sensing camera
CN104176272A (en) * 2014-08-06 2014-12-03 上海卫星工程研究所 Eight rod connection type non-contact satellite platform configuration
CN204695107U (en) * 2015-04-24 2015-10-07 西安羚控电子科技有限公司 Unmanned plane landing guidance device

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