CN208736367U - Multipoint strain gauging device based on laser digital speckle interference positioning - Google Patents

Abstract

This application discloses a kind of Multipoint strain gauging devices based on laser digital speckle interference positioning, comprising: mechanical arm, nanometer adjust platform, be installed on mechanical arm, to drive its movement by mechanical arm；Laser speckle strain detecting equipment, comprising: which the optical element out and measurement camera and positioning camera of first laser generating unit from light beam to measured point transmitting, measurement camera corresponding with first laser generating unit, second laser generating unit from light beams to following positioning target transmittings, positioning cameras corresponding with second laser generating unit for positioning for detecting, first laser generating unit and second laser generating unit end are both secured on nanometer adjustment platform；Positioning target corresponding with positioning camera, with diffusing reflection target surface；With the computer of mechanical arm, nanometer adjustment platform and the equal circuit connection of laser speckle strain detecting equipment.The application can be precisely accomplished the multiple spot strain detecting to body surface.

Description

Multipoint strain gauging device based on laser digital speckle interference positioning

Technical field

This application involves strain detecting technical fields, especially to object carry out strain detecting when detection device benchmark pose Location technology, and in particular to it is a kind of based on laser digital speckle interference positioning Multipoint strain gauging device.

Background technique

Strain detecting technology experienced long-run development, and it is various to be widely used to machinery, building, railway, aerospace etc. In the stress analysis of engineering structure.Steel construction strain measurement is that engineering staff carries out structural design optimization, understands structure stress shape State and an extremely important link for guaranteeing structure safety.How accurately measure structural strain, be each engineering Technical staff's very concern.

In recent years, with the continuous development of strain detecting technology, single-point measurement method, measurement accuracy and measurement range etc. are all It is being continuously improved, still, is being constantly in and relatively lags behind for the multiple spot strain detecting technology in construction steel structure field, still generally make Multipoint strain gauging is completed with resistance strain gage (hereinafter referred to as foil gauge), can not be provided for research structure design more quasi- Really, effective information is always one of the main reason for hindering the progress of steel construction experimental technique.Steel construction strain measurement is different from General measure, it is necessary to grasp along structure multiple spot (key node) Strain Distribution situation, especially understanding structural danger section The distribution of stress multiple spot and maximum stress value, whether it is reasonable for establishing Strength co-mputation theory or verifying design, and calculation method is The no safety for being correctly all related to building structure, therefore this patent application has very important significance.

Since foil gauge has light weight, easy for installation, cheap, still adopted extensively in steel construction load test at present With.But foil gauge temperature coefficient is big, single (direction strained after practical structures load is not really in strain measurement direction It is fixed), it is non-linear it is serious, consistency is poor, weak output signals and the disadvantages of poor anti jamming capability so that this method measurement error Greatly, effect is also undesirable.

With the fast development of digital camera and computer technology, optical digital image correlation technique is proved to be to answer variation Effective technological means is analysed, the technologies such as measurement accuracy, range and measurement of full field have all reached certain level.And as steel construction Strain measurement, it is necessary to obtain the multiple spot Strain Distribution situation (needing Multipoint strain gauging) along structure, design and mention for research structure For more accurate and effective information.Laser speckle detection at present is only used for single-point strain measurement, and spot measurement is simply used When the measurement of multiple spot steel construction, mainly have the disadvantage that and problem:

1, it must be configured according to measurement points and cover single-point laser strain detecting equipment more, one point of each device measuring, and It also cannot achieve interconnection between multiple equipment, usual measurement points are 10 or more and make acquisition cost huge.

2, camera, camera lens, light path part and laser light source mostly in set equipment etc. is variant, and it is consistent to directly affect measurement Property, the setting of equipment, adjustment and maintenance workload are larger.

3, the space measurement position of each point and posture are not quite similar, and the erecting device of every set equipment is different and needs loaded down with trivial details Manual adjustment, once measurement pose change erecting device adjustment it is very inconvenient.

4, measuring device occupied space is big, when there is multiple measured points in small area, because space limitation causes to measure Equipment installation conflicts with each other, then wherein one or more points can not implement strain detecting.

It 5,, can not when there is measured structure position or posture has larger change since the equipment such as camera are to be fixedly mounted Realize the important informations such as tracking measurement spatial pose delta data.

6, foil gauge is still widely used in current multiple spot strain detecting due to the above reasons, the disadvantage is that measurement temperature system Number is big, strain measurement direction is single, non-linear serious, weak output signals and poor anti jamming capability etc..

The above problem is not effectively improved always for many years.Therefore, change the backwardness face of Multipoint strain gauging technology Looks make more scientific measuring technique, wisdom, automation and precision have important meaning to construction steel structure technological progress Justice.

Different from simple body surface strain measurement, steel construction strain measurement must obtain the multiple spot along structure and answer variation Cloth situation.It is commonly used strain gauge method, foil gauge is attached to test point surface when measurement, lead is connected to strain measurement On instrument, since the shortcomings that foil gauge itself, makes measurement accuracy, range, direction and consistency all unsatisfactory.It is based in recent years Laser speckle strain measurement method gradually starts to apply, and measurement accuracy, range, the whole audience and consistency all obtain good Effect, but still may not apply to Multipoint strain gauging for these reasons, therefore, multiple spot high-precision strain measurement is always steel Key technical problem urgently to be resolved in structural test.

Summary of the invention

The purpose of the application, is: in view of the above-mentioned problems, the application provide it is a kind of based on laser digital speckle interference positioning it is more Point strain gauge means and method, can be precisely accomplished the multiple spot strain detecting to body surface.

The technical solution of the application is:

A kind of Multipoint strain gauging device based on laser digital speckle interference positioning characterized by comprising

Mechanical arm,

Nanometer adjustment platform, is installed on the mechanical arm, to drive its movement by the mechanical arm；

Laser speckle strain detecting equipment, the laser speckle strain detecting equipment include: to examine for emitting to measured point It surveys the first laser generating unit of light beam, measurement camera corresponding with the first laser generating unit, be used for following fixed Second laser generating unit, the positioning camera corresponding with the second laser generating unit of position target transmitting positioning light beam, institute That states first laser generating unit and second laser generating unit end goes out optical element and the measurement camera and described Positioning camera is both secured on the nanometer adjustment platform；

Corresponding with the positioning camera positioning target with diffusing reflection target surface；And

With the computer of the mechanical arm, nanometer adjustment platform and the equal circuit connection of laser speckle strain detecting equipment.

The application further includes following preferred embodiment based on the above technical solution:

The mechanical arm is movably connected in linear guide and drives the mechanical arm to lead along the straight line by servo motor Rail linear movement, the servo motor includes the motor servo driver connecting with the computer circuits.

The nanometer adjusts platform

It can be moved in translation nanometer translation stage along X-axis, Y-axis, Z axis, and

It is set to the nanometer turntable that can be rotated on the nanometer translation stage and around A axis, B axle, C axis, the A axis, B Axis, C axis are mutually perpendicular to arrange；

The laser speckle strain detecting equipment is set on the nanometer turntable.

The A axis and the X-axis extend in the same direction setting, and the B axle and the X-axis extend in the same direction setting, the C axis and institute It states Z axis and extends in the same direction setting.

The first laser generating unit and the second laser generating unit are respectively included along optical path direction successively cloth It sets:

Laser generator,

Optical fiber,

Optical fiber collimator,

Aperture, and

Beam expanding lens.

Three mirror surfaces evenly distributed in the circumferential direction are provided on the diffusing reflection target surface of the positioning target, described three A mirror surface is in same plane, and three laser corresponding with three mirror surfaces is fixedly installed at the positioning camera Displacement sensor.

The diffusing reflection target surface of the positioning target is carved with round " O " shape pattern and is located in described " O " shape pattern " ten " herringbone pattern at the heart.

The positioning target is provided at least two altogether.

The advantages of the application, is:

Ingenious " the micrometering amount " by laser speckle of the application with nano platform " micro-shifting is dynamic " to be combined, using speckle " face Domain " pose measuring method accurately reduces the spatial pose relationship of strain-Sensing device and target surface, makes its accurate repetition every time Same pose is navigated to, realizes laser speckle Multipoint strain gauging, the strain of General Promotion multiple spot (by measuring camera) in turn Measuring technique level, precision, range, the whole audience and consistency.It can be according to pose automatic laser speckle in measured point in CAD design figure Strain detecting equipment keeps the adjustment of its pose flexible and convenient.Strain-Sensing device occupies little space, and small-scale multiple spot can be realized Strain measurement, also achievable large-scale Multipoint strain gauging.Multipoint strain gauging device can not only measure strain information, also The information such as spatial warping posture and position after available deformation constitute a space multiple spot tracking mode steel construction measurement analysis system System provides more accurate and sufficient information for structural analysis, and the application has very high practical value and economic benefit.

Detailed description of the invention

The application is further described with reference to the accompanying drawings and embodiments:

Fig. 1 is the overall structure diagram of Multipoint strain gauging device in the embodiment of the present application；

Fig. 2 is the overall structure diagram of laser speckle strain detecting equipment in the embodiment of the present application；

Fig. 3 is the schematic diagram of Multipoint strain gauging device in the embodiment of the present application；

Fig. 4 is the structural schematic diagram that target target surface is positioned in the embodiment of the present application；

Fig. 5 is the structural schematic diagram that four sub-regions on target target surface are positioned in the embodiment of the present application；

Fig. 6 is the demonstration graph for carrying out Multipoint strain gauging in the embodiment of the present application to steel construction piece；

Fig. 7 is two subregion interference fringe variation diagrams in face；

Wherein: 1- mechanical arm, 101- manipulator motion controller, 2- nanometers of adjustment platforms, 201- nanometers of translation stages, 202- Nanometer turntable, 3- measurement camera, 4- positioning camera, 5- positioning target, 6- computer, 7- linear guide, 8- servo motor, 9- swash Optical generator, 10- optical fiber, 11- optical fiber collimator, 12- aperture, 13- beam expanding lens, 14- mirror surface, 15- laser displacement sensing Device, the measured point 16-.

Specific embodiment

Fig. 1 shows a tool of this Multipoint strain gauging device based on laser digital speckle interference positioning of the application Body embodiment mainly includes linear guide 7, servo motor 8, mechanical arm 1, laser speckle strain detecting equipment, positioning 5 and of target The structures such as computer 6.Wherein:

Mechanical arm 1 is movably connected in linear guide 7, can be moved forward and backward along linear guide 7.The mechanical arm 1 configuration There is mechanical arm motion controller 101, with the movement for controlling the mechanical arm 1.The effect of linear guide 7 is to increase mechanical arm 1 motion range, and then increase the detection range of laser speckle strain detecting equipment.

Servo motor 8 is sequentially connected by screw body and mechanical arm 1, for driving mechanical arm 1 before linear guide 7 After move.Servo motor 8 is also configured with motor servo driver, by motor servo driver control servo motor 8 Operation.

Nanometer adjustment platform 2 is mounted on mechanical arm 1, can drive nanometer adjustment platform 2 is synchronous to move when mechanical arm 1 acts It is dynamic.

Specifically, above-mentioned nanometer adjustment platform 2 includes nanometer translation stage 201 and nanometer turntable 202.Wherein nanometer translates Platform 201 can be moved in translation along X-axis, Y-axis, three direction of Z axis, and nanometer turntable 202 is set on nanometer translation stage 201, and Nanometer turntable 202 can be around A axis, B axle, the rotation of C axis.Identical as aforementioned X-axis, Y-axis, Z axis, A axis, B axle, C axis are also mutual It is arranged vertically.And laser speckle strain detecting equipment is specifically mounted on nanometer turntable 202, can thus be adjusted by nanometer The movement of platform 2 is flattened, and makes laser speckle strain detecting equipment that can either can surround X along X-axis, Y-axis, Z axis translation Axis, Y-axis, Z axis rotation so guarantee that laser speckle strain detecting equipment is at any 3 d pose.

X-axis described in the present embodiment, Y-axis, Z axis, A axis, B axle, C axis, are linear axis.And A axis is extended in the same direction with X-axis Setting (i.e. the two is arranged parallel), B axle and Y-axis extend in the same direction setting, and C axis and Z axis extend in the same direction setting.

The surface for positioning target 5 is in microparticulate structure, i.e. positioning target 5 has shaggy diffusing reflection target surface.

At least part component of laser speckle strain detecting equipment is (than measurement camera, light collimator described as follows Deng) be mounted on nanometer adjustment platform 2, when mechanical arm 1 drives nanometer adjustment platform 2 mobile, it is set to the nanometer and adjusts platform 2 On the corresponding component of laser speckle strain detecting equipment can also follow movement.Obviously, nanometer adjustment platform 2 itself can also be with Micro movement is carried out, so that the corresponding component of laser speckle strain detecting equipment thereon be driven to finely tune movement, it is therefore intended that Laser speckle strain detecting equipment can precisely be aligned and obtain accurate strain detecting value.

Computer 6 is as host computer and above-mentioned servo motor 8 (the specially motor servo driver of the servo motor), machine Tool arm 1 (the specially tool arm motion controller 101 of the mechanical arm), the equal circuit connection of laser speckle strain detecting equipment, with control The operation of each unit processed.

Identical with conventional laser speckle strain detecting equipment to be, the laser speckle strain detecting equipment of the present embodiment is also wrapped Include for measured point (i.e. the strain detecting point on testee surface) emit detection light beam first laser generating unit and Measurement camera 3 corresponding with aforementioned first laser generating unit.When practical application, first laser generating unit is to testee The strain detecting point (i.e. aforementioned measured point) on surface emits laser beam, shaggy (needing to carry out rough surface processing to it) The laser scattering beam can be in countless relevant wavelets by strain detecting point, these wavelets are interfered and presented in measurement camera 3 First speckle pattern of measured point out (certain speckle pattern, which is also transferred in above-mentioned computer 6, to be shown)；For a period of time Afterwards (after carrying out load or measured object generation temperature deformation to measured object), when first laser generating unit is again to testee The strain detecting point on surface emits identical laser beam, shows the of measured point after the laser scattering beam in measurement camera 3 Two speckle patterns.Once aforementioned measured point is strained, first speckle pattern and second speckle pattern necessarily have different Pattern.By relevant calculation can be showed in computer 6 different pattern first speckle pattern and second speckle pattern institute Corresponding interference fringe picture, which characterizes the strain size of measured point generation and should change direction, then passes through calculating It can obtain the strain size of measured point and should change direction.This so-called " laser speckle interferometry strain measurement technique ".

It is not difficult to find out that the device can drive laser speckle strain detecting to set by above-mentioned mechanical arm 1 and nanometer adjustment platform 2 Standby especially measurement camera 3 is moved to different positions, to obtain testee surface difference measured point (multiple measured points) Speckle pattern and interference fringe picture corresponding with speckle pattern, and then the strained situation of the multiple measured points in object analysis surface.? It is that, only with the device, can realize the Multipoint strain gauging to measured object with regard to saying.

By the introduction of the application background technique, we it is known that, the key of Multipoint strain gauging is to ensure that strain inspection The reorientation precision of device is surveyed, and the present embodiment meets this requirement:

With conventional laser speckle strain detecting equipment the difference is that the conventional laser speckle strain detecting of the present embodiment is set It is standby to be also configured with for the second laser generating unit to above-mentioned positioning target 5 transmitting positioning light beam and occur with second laser single The corresponding positioning camera 4 of member.Aforementioned first laser generating unit and second laser generating unit end go out optical element and Measurement camera 4 and positioning camera 6 are both secured on nanometer adjustment platform 2, in this way, first laser generating unit end goes out light member Part, second laser generating unit end go out optical element, positioning camera 4 with measure camera 3 four relative position be completely fixed. When its object is to carrying out strain measurement before and after the same test point, guaranteeing that aforementioned four are in same pose, so guaranteeing The accuracy of strain measurement.It makes a concrete analysis of as follows:

When the speckle pattern of some measured point in above-mentioned measurement camera 3 acquisition testee (usually steel construction object), Positioning camera 4 and second laser generating unit is allowed just to be directed at the diffusing reflection target surface of above-mentioned positioning target 5.With above-mentioned " laser speckle The principle of interference strain measurement technique " is identical: when second laser generating unit directive positions the coarse diffusing reflection target surface of target 5, target Face can scatter countless relevant wavelets, these scattering wavelets interfere the speckle for being formed in particular cross section (i.e. positioning camera 4) Figure.Due to speckle pattern have height randomness, i.e., any two in space at speckle pattern be all different, positioning camera 4 is adopted The speckle pattern of collection determines unique relative positional relationship between target surface and positioning camera 4 namely laser speckle strain detecting equipment (target surface is motionless, if the speckle pattern that front and back was photographed twice is completely the same, laser speckle strain detecting equipment front-rear position phase Together).And if front and back two is opened in speckle pattern, the displacement of each point and direction are all identical on regional area, flat in Fourier transform The superposition (hereinafter referred to as interference fringe picture) that the interference fringe of same intervals and same orientation is occurred that on face utilizes interference item Line figure can quantify front and back speckle pattern regional area positional relationship, then control by mechanical arm 1 and nanometer adjustment platform 2 Positioning camera 4 namely laser speckle strain detecting equipment displacement (including translate and rotate, wherein mechanical arm 1 is used for thick item, And nanometer adjustment platform 2 is used for fine tuning, the general stage only has nanometer adjustment platform 2 and moves, and mechanical arm 1 does not move), until Previous intervention bar graph disappears, and (the striped quantity of interference fringe picture gradually decreases, and finally completely disappears；Rather than because big inspection Interference fringe picture suddenly disappears caused by surveying error), show that 4 front and back pose of positioning camera (position and posture) is completely the same, And measure camera 3 and fixed with 4 relative position of positioning camera, so also pose (position before and after surface laser speckle strain detecting equipment Set and posture) it is completely the same, obtain the speckle pattern of corresponding measured point and speckle pattern pair is opened in front and back two with measurement camera 3 again at this time The interference fringe picture answered can accurately know strained situation before and after the measured point.

In order to cooperate the Multipoint strain gauging of the device, the positioning target 5 of multiple above structures is needed to configure.One positioning target A 5 corresponding measured points.Each measured point is disposed about a positioning target 5, and measured point and the spacing for positioning target 5 are equal to measurement phase Machine 3 guarantees that the target surface of positioning target 5 is substantially parallel with tested region at a distance from positioning camera 4 as far as possible.Once positioning the position of target 5 Appearance is determined, then its pose in entire measurement process must remain unchanged.

Also, in the present embodiment, above-mentioned positioning target 5 is substantially rounded, and round " O " shape figure is carved on diffusing reflection target surface Case and be located at " " ten " herringbone pattern at O " shape pattern center, outer rim of " O " the shape pattern around positioning 5 diffusing reflection target surface of target Side arrangement.And be provided on the diffusing reflection target surface of positioning target 5 along above-mentioned " circumferencial direction of O " shape pattern be evenly arranged three The mirror surface 14 of a very little, and three laser displacements corresponding with these three mirror surfaces are fixedly installed at above-mentioned positioning camera 4 Sensor 15 (abbreviation direction finder).When its purpose obtains positioning 5 speckle pattern of target, guarantee the camera lens and positioning target target of positioning camera 4 Face is parallel, it is ensured that positioning camera 4 and measure camera 3 camera lens face and it is initial when camera lens face be in plane, eliminate off face It is displaced (Y-axis) deviation and out of plane rotation (around A, C axis) deviation；I.e. camera lens face and be initially positioned in same plane), with facilitate survey Amount.It is specifically described as follows:

The present apparatus relocates key technology, firstly, the ingenious uniqueness using laser specklegram, determines target surface and strain The uniqueness in detection device space " relationship "；Secondly, laser speckle interference measuring precision is high；Third, speckle interference fringe pattern are Quantification parsing to two different speckle pattern correlations, points the direction for strain-Sensing device micro-displacement with micro- pose adjustment And size；4th, according to third step, strain-Sensing device microbit appearance is adjusted by nano platform, is approached repeatedly automatically and final Make the relative pose of strain-Sensing device and target surface and initial pose completely the same.This novel " one direction " speckle face domain pose Measurement method is more scientific, more acurrate.

The present embodiment is ingenious to be used as space orientation measuring tool, essence for " speckle pattern " face domain (face region rather than light pencil point) The spatial relationship of laser speckle strain detecting equipment and target surface is reduced quasi-ly, ensures that repetitive positioning accuracy.It is practical to survey Target is positioned when amount to be fixed near position to be measured.In order to describe with convenience of calculation by target surface initial attitude be it is vertical and perpendicular to Y-axis adjusts the opposite position of positioning camera 4 namely laser speckle strain detecting equipment and positioning target target surface that is, in XOZ plane It sets, three direction finders at positioning camera 4 is respectively aligned to three mirror surfaces 14, displacement measurement is adjusted to identical, positions at this time The camera lens face of camera 4 is parallel with target surface.When to drive laser speckle strain detecting equipment thereon to again move into tested for mechanical arm When point reorientation, according to three direction finder measured value adjust automatically nano platforms, make positioning camera 4 camera lens face and it is initial when mirror Head are in a plane, eliminate acoplanarity displacement (Y-axis) deviation and out of plane rotation (around A, C axis) deviation.

Above-mentioned first laser generating unit and second laser generating unit adopt a split structure, and the two respectively includes edge Optical path direction be sequentially arranged: laser generator 9, optical fiber 10, optical fiber collimator 11, aperture 12 and beam expanding lens 13. And aforementioned optical fiber collimator 11, aperture 12 and beam expanding lens 13 are that first laser generating unit and second described above swashs Light generating unit end goes out optical element, and optical fiber collimator 11, aperture 12 and beam expanding lens 13 are fixed on nanometer adjustment platform 2.Laser generator 9 is mainly made of driving power and laser head.

For the working principle for integrally understanding the present apparatus convenient for reader, refer again to shown in Fig. 1 to Fig. 7, now by the present embodiment this The measurement process of kind strain gauge means is integrally described below:

In actual use, installation positioning target 5, the spacing for positioning target 5 and measured point are basic near each measured point side Equal to measurement the distance between camera 3 and positioning camera 4, keeps the target surface for positioning target 5 substantially parallel with tested region, position target 5 It is fixed on an independent stationary object (not on tested component) as the positioning plane of reference.Adjusting nanometer adjustment platform makes XYZ tri- The intersection point of tri- rotary shafts of intersection point and ABC of a translation shaft faces the middle position of positioning target 5 and measured point.

The optical components such as the measurement camera 3 of laser speckle strain detecting equipment, positioning camera 4, laser generating unit have been consolidated It is fixed.Measured point position, posture are inputted when measurement.It is by linear guide 7 and mechanical arm 1 that laser speckle strain detecting equipment is mobile To position to be measured, control mechanical arm 1 is manually adjusted, makes the lens axis of positioning camera 4 and swashing for second laser generating unit Light optical path axis intersection position is the vertical target surface of lens axis for positioning the target surface center wherein positioning camera 4 of target 5；Make to measure phase The lens axis of machine 3 and the laser optical path crossing point of axes position of first laser generating unit are tested region (measured point) center, The wherein vertical tested region of lens axis.Three mirror surfaces 14 on narrow laser beam alignment positioning target that three direction finders issue, lead to Overregulating nanometer adjustment platform keeps three measured values identical, and both the camera lens face of positioning camera was parallel with target surface.Record measured point this When mechanical arm and nanometer adjustment platform initial posture information, check target surface speckle pattern and measured point speckle pattern shooting quality.It presses The above method successively operates all measured points one time.

For ease of description by taking Fig. 6 commonly uses basic steel construction piece as an example, before not being applied from above load, computer is by machine Tool arm 1 is sent to machine arm controller 101 from the motion track of initial point to measured point M1, it controls linear guide and mechanical arm Laser speckle strain detecting equipment is moved in front of the M1 of measured point by setting track, shoots initial target surface speckle pattern and measured point The initial speckle pattern of M1.Laser speckle strain detecting equipment is successively pressed to using mechanical arm 1 setting track respectively according to the above method Be moved to measured point M2, M3, M4 (only take for convenience 4 key nodes explanation), and shoot initial target surface speckle pattern and The initial speckle pattern in measured point, all mechanical arm 1 returns to initial point after measurement.

After increasing certain load, computer 6 controls motion track of the mechanical arm 1 from initial point to measured point M1 again and sends Give machine arm controller, it control linear guide and mechanical arm by setting track by laser speckle strain detecting equipment be moved to by In front of measuring point M1, but must carry out just can be carried out strain measurement after reorientation amendment at this time, Multipoint strain gauging method be divided into Lower four steps:

The first step is figure coarse positioning.By the position, shape and size of " ten " word in present image and " O " shape pattern, It is compared respectively with initial target surface figure, is directly entered in next step if precision has been met the requirements, is otherwise received by automatic adjustment Rice adjustment platform three-dimensional coordinate and three axis rotation, make in image the location of " ten " word and annulus pattern, form and dimension with Consistent in initial target surface figure, strain-Sensing device positioning accuracy is in ± 10 microns at this time.

Second step is acoplanarity displacement and rotates fine positioning from face.Judge three direction finders measured value whether with initial value phase Together, it is directly entered if meeting the requirements (identical) in next step, otherwise according to the offset relation between three measured values, adjust automatically The Y-axis of nanometer adjustment platform is translated and is rotated around A, C axis, keeps the measured value of three direction finders identical with initial value, at this time Positioning camera 4 and measure camera 3 camera lens face and be initially positioned in same plane.In addition, the present embodiment is in order to ensure from face What is positioned is accurate, is verified using digital speckle image relative theory to above-mentioned processing result, verification method is as follows: selection is worked as Preceding speckle image subregion (such as R1 and R2), obtains related coefficient of the subregion in initial speckle pattern by relevant calculation, such as Fruit related coefficient is greater than 0.85, then illustrates this effectively from face positioning, positioning result is correctly then transferred to third step, otherwise returns again Return the first step.

Third step is that fine positioning is rotated in in-plane displacement and face.Four sub-regions are chosen on the speckle pattern of positioning target target surface (R1, R2, R3, R4, such as Fig. 5) asks poor, Fourier change by carrying out to corresponding sub-region in current speckle pattern and initial speckle pattern It changes with after the calculation processings such as various trend pass filterings, the interference fringe picture of all subregion can be obtained.According to the striped of four sub-regions The consistency in direction can decide whether that there are rotating deviation in face (perpendicular to the B axles of target surface), by receiving if inconsistent If the rotation of rice adjustment platform 2 is consistent to eliminate the aforementioned four interference fringe direction, (for the time being) only has in-plane displacement, All there may be so the direction vector for being oriented to the two synthesis of striped for X-axis and Z axis both direction offset deviation at this time.This When need to calculate the displacement of each axis (X-axis and Z axis) according to interference fringe vector that (Y-axis is by above three mirror surface 14 Aligned with laser displacement sensor 15), and then the movement of both direction nano platform is adjusted, make the speckle for reflecting deviation Fringe number, which is constantly reduced, (indicates that the in-plane displacement of speckle pattern is constantly reduced.And the statement of aforementioned " for the time being " is explained as follows: if In-plane displacement is larger, and rotates very little (then stripe direction " for the time being " is almost the same) in face, then is reduced to very when in in-plane displacement Hour, the inconsistent of stripe direction can just show, need to adjust the rotation of nano platform again to eliminate in face and rotate at this time, until Be zero (two spaces speckle pattern is completely coincident), i.e., the relative pose of strain-Sensing device camera lens face and target surface with it is initial when it is complete Unanimously.Rotation and adjustment of displacement may be that alternately, two subregions are shown in nano platform adjustment interference fringe variation in face Fig. 7.By laser digital speckle measurement method can by resetting resolution ratio be less than optical maser wavelength half, about 0.3 Micron (reducing laser long (such as green laser) also can be improved precision), ensures that repetitive positioning accuracy.It ensure that stress structure Part laser speckle strain measurement needs.

4th step is strain measurement.After the completion of strain-Sensing device positioning, measurement camera 3 shoots tested after structure loads Before the laser specklegram in region (i.e. measured point), with measured point load initial speckle pattern carry out image ask poor, Fourier transform and The processing of the associated pictures such as gaussian filtering and calculating, find out the strain value in the region (measured point).

Nanometer adjustment platform can be returned to initial position automatically after being measured by each measured point, equally using swashing when return Light speckle closed loop localization method, that is, ensure nanometer adjustment platform reach initial position when clap speckle pattern with start adjust leave When speckle pattern unanimously both number of interference fringes between the two had been reduced to zero.Then by linear guide and mechanical arm according to setting rail Strain-Sensing device is moved to measured point M2 from measured point M1 by mark, equally first carries out reorientation amendment, then complete strain measurement； Strain-Sensing device is successively moved to measured point M3, M4 implementation measurement according to the above method, and (steel construction strain measurement is stable state survey Amount)；4 points are measured rear mechanical arm and return to initial point.Loading force is gradually increased, is recycled again real respectively to all 4 points Apply strain measurement.

Certainly, above-described embodiment is only the technical concepts and features for illustrating the application, and its object is to make people much of that Solution present context is simultaneously implemented accordingly, and the protection scope of the application can not be limited with this.It is all according to the application major technique The equivalent transformation or modification that the Spirit Essence of scheme is done should all be covered within the scope of protection of this application.

Claims (8)

1. a kind of Multipoint strain gauging device based on laser digital speckle interference positioning characterized by comprising

Mechanical arm (1),

Nanometer adjustment platform (2), is installed on the mechanical arm, to drive its movement by the mechanical arm；

Laser speckle strain detecting equipment, the laser speckle strain detecting equipment include: for emitting detection light to measured point The first laser generating unit of beam, is used for following positioning measurement camera (3) corresponding with the first laser generating unit The second laser generating unit of target transmitting positioning light beam, positioning camera (4) corresponding with the second laser generating unit, institute State optical element and the measurement camera (3) and the institute out of first laser generating unit and second laser generating unit end Positioning camera (4) is stated to be both secured on nanometer adjustment platform (2)；

Corresponding with the positioning camera positioning target (5) with diffusing reflection target surface；And

With the computer of the mechanical arm (1), nanometer adjustment platform (2) and the equal circuit connection of laser speckle strain detecting equipment (6)。

2. the Multipoint strain gauging device as described in claim 1 based on laser digital speckle interference positioning, which is characterized in that The mechanical arm (1) is movably connected on linear guide (7) and drives the mechanical arm (1) along described straight by servo motor (8) Line guide rail (7) linear movement, the servo motor (8) includes the motor servo driver with the computer (6) circuit connection.

3. the Multipoint strain gauging device as described in claim 1 based on laser digital speckle interference positioning, which is characterized in that The nanometer adjusts platform (2)

Nanometer translation stage (201) can be moved in translation along X-axis, Y-axis, Z axis, and

It is set to the nanometer turntable (202) that can be rotated on the nanometer translation stage (201) and around A axis, B axle, C axis, institute A axis, B axle, C axis is stated to be mutually perpendicular to arrange；

The laser speckle strain detecting equipment is set on the nanometer turntable (202).

4. the Multipoint strain gauging device as claimed in claim 3 based on laser digital speckle interference positioning, which is characterized in that The A axis and the X-axis extend in the same direction setting, and the B axle and the X-axis extend in the same direction setting, and the C axis and the Z axis are same To be extended.

5. the Multipoint strain gauging device as described in claim 1 based on laser digital speckle interference positioning, which is characterized in that What the first laser generating unit and the second laser generating unit respectively included setting gradually along optical path direction:

Laser generator (9),

Optical fiber (10),

Optical fiber collimator (11),

Aperture (12), and

Beam expanding lens (13)；

The optical fiber collimator (11), the aperture (12) and the beam expanding lens (13) are fixed on the nanometer adjustment platform (2) on.

6. the Multipoint strain gauging device as described in claim 1 based on laser digital speckle interference positioning, which is characterized in that Three mirror surfaces (14) evenly distributed in the circumferential direction are provided on the diffusing reflection target surface of positioning target (5), described three A mirror surface (14) is in same plane, is fixedly installed at the positioning camera (4) corresponding with three mirror surfaces Three laser displacement sensors (15).

7. the Multipoint strain gauging device as claimed in claim 6 based on laser digital speckle interference positioning, which is characterized in that The diffusing reflection target surface of positioning target (5) is carved with round " O " shape pattern and is located at described " O " shape pattern center " ten " herringbone pattern.

8. the Multipoint strain gauging device as described in claim 1 based on laser digital speckle interference positioning, which is characterized in that The positioning target (5) is provided at least two altogether.