CN113177340A - Three-dimensional contact stress characterization method and device based on stereoscopic vision - Google Patents
Three-dimensional contact stress characterization method and device based on stereoscopic vision Download PDFInfo
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Abstract
The application discloses a three-dimensional contact stress characterization method and device based on stereoscopic vision, wherein the method comprises the following steps: the upper surface of the transparent elastic body is contacted with an external object to generate deformation, so that the characteristic points on the characteristic layer move; collecting the movement of the characteristic points through a stereoscopic vision system, performing image operation on the characteristic points, and calculating a surface three-dimensional displacement field; and solving an elastic mechanics equation or a finite element model according to the constitutive relation of the elastic body to obtain the stress distribution applied to the upper surface of the three-way contact stress characterization system. The method of the embodiment of the application realizes the representation of normal and tangential contact stress with high spatial resolution and time resolution with small structural complexity.
Description
Technical Field
The application relates to the technical field of force sensing, in particular to a three-dimensional contact stress characterization method and device based on stereoscopic vision.
Background
The contact stress when an object is in contact, adhered or moved on a surface is a key issue in various physical, biological and engineering fields. The contact stress is characterized by a spatial distribution. Currently, in the related characterization techniques, the common interfacial force measurement methods (such as cantilever strain gauge, balance, and atomic force microscope) can only measure the average value on the contact surface, and cannot obtain the stress distribution information of the contact interface. The stress distribution information for representing the contact interface has important values in the aspects of explaining the origin of friction and adhesion, representing the motion mechanism of organisms, realizing the smart operation of a manipulator and the like.
In addition, with a multitude of electrode array structures, existing e-skins can characterize the distribution of normal and shear forces with a certain spatial resolution. However, the fine sensor array requires the introduction of a complex wiring system, which also increases the complexity of signal processing, and limits the high spatial resolution characterization capability, which is yet to be improved.
Content of application
The application provides three-dimensional contact stress characterization and a device based on stereoscopic vision to solve the problems that a complex line system needs to be introduced into a fine sensor array, the complexity of signal processing is increased, and the high spatial resolution characterization capability is limited.
The embodiment of the first aspect of the application provides a three-way contact stress characterization method based on stereoscopic vision, wherein, the three-way contact stress characterization system includes a transparent elastomer fixed on a transparent support, a feature layer covering on the transparent elastomer, an opaque layer covering on the feature layer, and a stereoscopic vision system for capturing and reconstructing displacement field information of the feature, wherein, the method includes the following steps: the upper surface of the transparent elastic body is contacted with an external object to generate deformation, so that the characteristic points on the characteristic layer move; shooting the movement of the characteristic points by the stereoscopic vision system including but not limited to a binocular stereoscopic camera, performing image operation on the characteristic points, and calculating a surface layer three-dimensional displacement field; and solving an elastic mechanics equation or a finite element model according to the constitutive relation of the elastic body to obtain the stress distribution applied to the upper surface of the three-way contact stress characterization system.
Optionally, in an embodiment of the present application, the deforming the upper surface of the transparent elastic body by contacting with an external object to move the feature point on the feature layer includes: selecting a target calibration device according to the stereoscopic vision system, and obtaining internal and external parameters of the three-way contact stress characterization system through calibration measurement; placing a characteristic layer covered with a speckle coating and a transparent elastomer of the opaque coating, and turning on a light source to adjust the stereoscopic vision system to focus on the characteristic layer to start image acquisition or scanning imaging.
Optionally, in an embodiment of the present application, the acquiring, by the stereo vision system, the feature point movement, and performing image operation on the feature point to calculate a surface three-dimensional displacement field includes: and contacting the force or the object to be measured with the upper surface of the opaque coating, applying an external contact force, and acquiring an image of the characteristic layer by performing image acquisition or scanning by a stereoscopic vision system.
Optionally, in an embodiment of the present application, the capturing, by the stereoscopic vision system, the feature point movement, and performing image operation on the feature point to calculate a surface three-dimensional displacement field further includes: performing frame-by-frame feature point matching according to the image of the feature layer, and performing three-dimensional reconstruction on the feature points of the feature layer to obtain three-dimensional coordinates of the speckle layer at different moments; and subtracting the initial coordinate from the three-dimensional coordinate to obtain surface deformation fields at different moments.
Optionally, in an embodiment of the present application, the solving an elasto-mechanical equation according to an elasto-mechanical constitutive relation to obtain a stress distribution applied to an upper surface of the three-way contact stress characterization system includes: and solving the elastic mechanical equation or the finite element model by utilizing the preset constitutive model of the transparent elastomer and the surface deformation field to obtain the three-dimensional stress distribution applied to the surface of the transparent elastomer.
The embodiment of the second aspect of the present application provides a three-way contact stress characterization device based on stereovision, its characterized in that, wherein, three-way contact stress characterization system is including being fixed in transparent elastomer on the transparent support body, cover in feature layer on the transparent elastomer, cover in opaque layer on the feature layer and catch and reconstruct the stereovision system of the displacement field information of feature, wherein, the device includes: the deformation module is used for generating deformation by utilizing the contact of the upper surface of the transparent elastic body and an external object so as to move the characteristic points on the characteristic layer; the acquisition module is used for acquiring the movement of the characteristic points through the stereoscopic vision system and carrying out image operation on the characteristic points to obtain a surface layer three-dimensional displacement field; and the characterization module is used for solving an elastic mechanical equation or a finite element model according to the constitutive relation of the elastomer to obtain the stress distribution applied to the upper surface of the three-way contact stress characterization system.
Optionally, in an embodiment of the present application, the deformation module is specifically configured to select a target calibration device according to the stereoscopic vision system, obtain internal and external parameters of the three-way contact stress characterization system through calibration measurement, place the feature layer covered with the speckle coating and the transparent elastomer of the opaque coating, turn on the light source, adjust the stereoscopic vision system to focus on the feature layer, and start image acquisition or scan imaging.
Optionally, in an embodiment of the present application, the acquisition module is specifically configured to contact a force or an object to be measured with the upper surface of the opaque coating, apply an external contact force, and acquire an image of the feature layer obtained by image acquisition or scanning by a stereoscopic vision system.
Optionally, in an embodiment of the present application, the acquisition module is further configured to perform frame-by-frame feature point matching according to the image of the feature layer, perform three-dimensional reconstruction on the feature points of the feature layer, obtain three-dimensional coordinates of the speckle layer at different times, and subtract the initial coordinates from the three-dimensional coordinates, to obtain surface deformation fields at different times.
Optionally, in an embodiment of the present application, the characterization module is specifically configured to obtain, by using a preset constitutive model of the transparent elastic body and the surface deformation field, a three-dimensional stress distribution applied to the surface of the transparent elastic body by solving the elastic mechanical equation or solving a finite element model.
The stress field is calculated by the measured deformation field through an image method, mature technology of a high-resolution camera and continuously developed image processing algorithms can be fully utilized, meanwhile, the structural complexity is greatly reduced, and meanwhile, the normal and tangential contact stress characterization of high spatial resolution and time resolution is realized. Therefore, the problems that a complex line system needs to be introduced into a fine sensor array, the complexity of signal processing is increased, and the high spatial resolution characterization capability is limited are solved.
Additional aspects and advantages of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present application.
Drawings
The foregoing and/or additional aspects and advantages of the present application will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a flowchart of a three-dimensional contact stress characterization method based on stereoscopic vision according to an embodiment of the present application;
FIG. 2 is a schematic structural diagram of a three-way contact stress characterization system according to one embodiment of the present application;
FIG. 3 is a flowchart of a three-dimensional contact stress characterization method based on stereo vision according to an embodiment of the present application
Fig. 4 is an exemplary diagram of a three-dimensional contact stress characterization device based on stereo vision according to an embodiment of the present application.
Detailed Description
Reference will now be made in detail to embodiments of the present application, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are exemplary and intended to be used for explaining the present application and should not be construed as limiting the present application.
The three-dimensional contact stress characterization and device based on stereoscopic vision according to the embodiment of the application are described below with reference to the attached drawings. In the method, the stress field is calculated by measuring the deformation field through an image method, the mature technology of a high-resolution camera and a continuously developed image processing algorithm can be fully utilized, the structural complexity is greatly reduced, and the normal and tangential contact stress with high spatial resolution can be represented. Therefore, the problems that a complex line system needs to be introduced into a fine sensor array, the complexity of signal processing is increased, and the high spatial resolution characterization capability is limited are solved.
Specifically, fig. 1 is a schematic flowchart of a three-dimensional contact stress characterization method based on stereoscopic vision according to an embodiment of the present application.
As shown in fig. 1, the three-dimensional contact stress characterization method based on stereoscopic vision includes the following steps:
first, a three-dimensional contact stress characterization system is described, which includes a transparent elastic body fixed on a transparent support, a feature layer covering the transparent elastic body, an opaque layer covering the feature layer, and a stereoscopic vision system for capturing and reconstructing displacement field information of the feature. It should be noted that, in the embodiments of the present application, but not limited to, the binocular camera is used as a stereoscopic vision system, and the stereoscopic vision system may be a technical means capable of providing spatial stereoscopic vision, such as a binocular camera, a confocal microscope, and a laser radar
Specifically, as shown in fig. 2, the stereoscopic vision-based three-way contact stress characterization system includes: the transparent elastomer (3) is usually fixed on a transparent support (4) with higher rigidity, and the upper surface of the transparent elastomer is covered with an extremely thin characteristic layer (2) which is characterized by high-contrast spots distributed randomly; an extremely thin opaque coating (1) is covered on the characteristic layer (2). The stereo vision system (5) is used to capture and reconstruct displacement field information of the feature layer (2).
Next, in step S101, the upper surface of the transparent elastic body is contacted with an external object to generate deformation, so that the feature point on the feature layer moves.
It can be understood that the embodiment of the application firstly utilizes the deformation generated by the contact of the upper surface of the elastic body and an external object to cause the characteristic point of the speckle layer to move.
Deformation may be understood as the elasticity of the layer containing features near the surface that may identify and provide deformation characteristics for the stereo vision system. In order to avoid interference from external objects, the preferred shooting angle is to cover the back or side of the feature layer, and may be equivalent to the back or side by means of a mirror or the like. If the stereo vision system adopts a binocular camera, the characteristic points of the characteristic layer can be image spots obtained by paint spraying, pattern transfer printing, micro-nano etching, particle deposition and the like.
Optionally, in an embodiment of the present application, the deformation caused by the contact between the upper surface of the transparent elastomer and the external object causes the feature point on the feature layer to move, including: selecting a target calibration device according to the stereoscopic vision system, and obtaining internal and external parameters of the three-way contact stress characterization system through calibration measurement; placing the characteristic layer covered with the speckle coating and the transparent elastomer of the opaque coating, and turning on the light source to adjust the stereoscopic vision system to focus on the characteristic layer to start image acquisition or scanning imaging.
For example, referring to fig. 2, firstly, a suitable calibration device is selected according to the selected stereoscopic vision system (5), and internal and external parameters of the system are obtained through calibration measurement; placing a transparent elastic body (3) covered with a speckle coating (2) and an opaque coating (1), turning on a light source (6), adjusting a stereoscopic vision system (5) to focus on the characteristic layer (2), and starting image acquisition or scanning imaging.
In step S102, the movement of the feature points is collected by a stereoscopic vision system such as a binocular camera, and the feature points are subjected to image operation to calculate a surface three-dimensional displacement field.
Secondly, the feature points are shot through a binocular stereo camera, and image operation is carried out on the feature points to calculate a surface layer three-dimensional displacement field.
Optionally, in an embodiment of the present application, the capturing the feature point movement by a stereoscopic vision system such as a binocular camera, and performing image operation on the feature point to calculate a surface three-dimensional displacement field includes: and (3) contacting the force or the object to be measured with the upper surface of the opaque coating, applying an external contact force, and acquiring an image of the characteristic layer by performing image acquisition or scanning by a stereoscopic vision system such as a binocular camera.
Further, as shown in fig. 2, the force or object to be measured is contacted with the upper surface of the opaque coating (1), the external contact force is applied, the external force or object is removed after the contact is tested, and the image acquisition or scanning is finished.
Optionally, in an embodiment of the present application, the method for acquiring the movement of the feature points by using a stereoscopic vision system such as a binocular camera, performing image operation on the feature points, and calculating a surface three-dimensional displacement field further includes: performing frame-by-frame feature point matching according to the image of the feature layer, and performing three-dimensional reconstruction on the feature points of the feature layer to obtain three-dimensional coordinates of the speckle layer at different moments; and subtracting the initial coordinate from the three-dimensional coordinate to obtain surface deformation fields at different moments.
Further, with reference to fig. 2, the collected image of the feature layer (2) is subjected to frame-by-frame feature point matching, and the feature points of the feature layer (2) are subjected to three-dimensional reconstruction to obtain three-dimensional coordinates of the speckle layer (2) at different times; and (4) subtracting the initial coordinates without deformation obtained in the step (2) to obtain deformation fields at different moments.
In step S103, an elastic mechanical equation or a finite element model is solved according to the elastic body constitutive relation, so as to obtain a stress distribution applied to the upper surface of the three-way contact stress characterization system.
Finally, according to the predetermined constitutive relation of the elastomer, solving the elastic mechanical equation, the stress distribution applied on the upper surface can be measured on line
Optionally, in an embodiment of the present application, solving an elasto-mechanical equation according to an elastomer constitutive relation to obtain a stress distribution applied to an upper surface of the three-way contact stress characterization system includes: and obtaining the three-dimensional stress distribution applied to the surface of the transparent elastomer by solving an elastic mechanical equation or a finite element model by utilizing a preset constitutive model and a surface layer deformation field of the transparent elastomer.
Referring to fig. 2, according to the constitutive model of the transparent elastic body (3) determined in advance and the surface layer deformation field measured in step 4, the three-dimensional stress distribution applied to the surface of the transparent elastic body (3) is obtained by solving a mechanical algorithm such as an elastic mechanical equation or finite element simulation.
In summary, the embodiment of the application reconstructs the surface deformation field and the external force field of the elastomer by using the stereo camera and the image processing algorithm, a complex circuit system is omitted, normal and tangential stress distributions can be represented simultaneously, a general sensing array can only represent pressure distribution, and by selecting a proper image algorithm, a visual system and the elastomer, the high spatial resolution can be achieved, and meanwhile, the force precision and the measuring range can be adjusted.
The operation of the embodiment of the present application is described below with a specific embodiment, as shown in fig. 3.
First, the system on which embodiments of the present application are based includes a stereo camera, a light source, a transparent elastomer, a transparent support, a feature layer, an opaque coating, and a support structure.
The upper surface of the elastic body is contacted with an external object to generate deformation, so that the characteristic points of the characteristic layer move. The method comprises the following steps of shooting the movement of characteristic points through a binocular stereo camera, carrying out image operation on the characteristic points to calculate a surface layer three-dimensional displacement field, solving an elastic mechanical equation according to a predetermined elastic body constitutive relation, and measuring the stress distribution applied to the upper surface on line, wherein the method comprises the following specific steps:
step S1: and placing a calibration plate, and obtaining internal and external parameters of the system and the camera through calibration and measurement.
Step S2: placing the transparent elastomer (3) covered with the characteristic layer (2), turning on the light source (6), adjusting the focal length of the stereo camera (5) to focus on the characteristic layer (2)
Step S3: the stereo camera (5) is connected with a computer through communication means such as a USB line, and at least one image is recorded as an initial image of an undeformed surface and is used as a deformation measurement reference.
Step S4: the force or object to be measured is placed or applied to the surface and the speckle image of the surface is recorded until the test is complete.
Step S5: performing correlation matching on feature units in images shot by two cameras and different frames of images of the same camera by using a three-dimensional Digital Image Correlation (DIC) algorithm, and obtaining a three-way displacement field X according to calibrated system parameters; calculating the three-way displacement field X of the reference image in the step 40(ii) a Obtaining a surface three-dimensional deformation field u-X according to the reference displacement field0。
Step S6: and (5) solving an elastic mechanical equation according to a predetermined constitutive model of the transparent elastomer (3) and the surface deformation field measured in the step (5) to obtain an applied surface stress field. In a preferred embodiment of the invention, the iterative solution may be performed according to the theory of contact mechanics. The specific principle is as follows: the deformation fields u in the three directions obtained in the step (5)iThen stress field p in three directionsjCan be expressed as
ui＝Gij*pj(i，j＝x，y，z)，
Wherein G isijTo influence the coefficient matrix, "+" stands for a two-dimensional convolution operation. GijCan be specifically expressed as:
wherein, E', E*，μ*μ' is determined by the constitutive equation of the transparent elastomer (3). Solving the stress field p according to the variation principlejThe extremum problem, which can be equated to a generalized quadratic function, is:
step S7: the above problem can be solved by a conjugate gradient method; the introduction of fast fourier transforms can improve the convolution computation efficiency. ObtainObtaining stress distribution force pjThen, the total contact force in three directions can be obtained by integrating the calculation domain.
According to the three-dimensional contact stress characterization method based on the stereoscopic vision, the stress field is calculated by the measured deformation field through the image method, the mature technology of the high-resolution camera and the continuously developed image processing algorithm can be fully utilized, the structural complexity is greatly reduced, and the normal and tangential contact stress characterization with high spatial resolution is realized.
Next, a three-dimensional contact stress characterization device based on stereoscopic vision according to an embodiment of the present application is described with reference to the drawings.
Fig. 4 is a block diagram of a three-dimensional contact stress characterization device based on stereoscopic vision according to an embodiment of the present application.
As shown in fig. 4, the three-dimensional visual-based contact stress characterization device 10 includes: a deformation module 100, an acquisition module 200, and a characterization module 300.
Specifically, the deformation module 100 is configured to generate deformation by contacting an upper surface of the transparent elastomer with an external object, so that the feature point on the feature layer moves.
And the acquisition module 200 is configured to acquire the movement of the feature points through a stereoscopic vision system, and perform image operation on the feature points to obtain a surface layer three-dimensional displacement field.
And the characterization module 300 is configured to solve an elastic mechanics equation or a finite element model according to the elastic body constitutive relation to obtain a stress distribution applied to the upper surface of the three-way contact stress characterization system.
Optionally, in an embodiment of the present application, the deformation module 100 is specifically configured to select a target calibration device according to the stereoscopic vision system, obtain internal and external parameters of the three-dimensional contact stress characterization system through calibration measurement, place the feature layer covered with the speckle coating and the transparent elastomer of the opaque coating, turn on the light source, adjust the stereoscopic vision system to focus on the feature layer, and start image acquisition or scan imaging.
Optionally, in an embodiment of the present application, the acquiring module 200 is specifically configured to contact a force or an object to be measured with the upper surface of the opaque coating, apply an external contact force, and acquire an image of the feature layer obtained by image acquisition or scanning by the stereoscopic vision system.
Optionally, in an embodiment of the present application, the acquisition module 200 is further configured to perform frame-by-frame feature point matching according to an image of the feature layer, perform three-dimensional reconstruction on the feature points of the feature layer, obtain three-dimensional coordinates of the speckle layer at different times, and subtract the initial coordinates from the three-dimensional coordinates, to obtain surface deformation fields at different times.
Optionally, in an embodiment of the present application, the characterization module 300 is specifically configured to obtain a three-dimensional stress distribution applied to the surface of the transparent elastic body by solving an elastic mechanical equation or by solving a finite element model using a preset constitutive model of the transparent elastic body and a surface deformation field.
It should be noted that the foregoing explanation of the embodiment of the three-dimensional contact stress characterization method based on stereoscopic vision also applies to the three-dimensional contact stress characterization device based on stereoscopic vision of this embodiment, and details are not repeated here.
According to the three-dimensional contact stress characterization device based on the stereoscopic vision, the stress field is calculated by the measured deformation field through the image method, the mature technology of the high-resolution camera and the continuously developed image processing algorithm can be fully utilized, meanwhile, the structural complexity is greatly reduced, and the characterization of the normal and tangential contact stresses with high spatial resolution is realized.
In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or N embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, "N" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more N executable instructions for implementing steps of a custom logic function or process, and alternate implementations are included within the scope of the preferred embodiment of the present application in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of implementing the embodiments of the present application.
It should be understood that portions of the present application may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the N steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. If implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
Claims (10)
1. A three-dimensional contact stress characterization method based on stereoscopic vision is characterized in that a three-dimensional contact stress characterization system comprises a transparent elastic body fixed on a transparent support body, a characteristic layer covering the transparent elastic body, an opaque layer covering the characteristic layer and a stereoscopic vision system for capturing and reconstructing displacement field information of the characteristic, wherein the three-dimensional contact stress characterization method comprises the following steps:
the upper surface of the transparent elastic body is contacted with an external object to generate deformation, so that the characteristic points on the characteristic layer move;
acquiring the movement of the characteristic points through the stereoscopic vision system, performing image operation on the characteristic points, and calculating a surface three-dimensional displacement field; and
and solving an elastic mechanics equation or a finite element model according to the constitutive relation of the elastic body to obtain the stress distribution applied to the upper surface of the three-way contact stress characterization system.
2. The method of claim 1, wherein the deforming by contact of the transparent elastomer upper surface with an external object to cause movement of the feature points on the feature layer comprises:
selecting a target calibration device according to the stereoscopic vision system, and obtaining internal and external parameters of the three-way contact stress characterization system through calibration measurement;
placing a characteristic layer covered with a speckle coating and a transparent elastomer of the opaque coating, and turning on a light source to adjust the stereoscopic vision system to focus on the characteristic layer to start image acquisition or scanning imaging.
3. The method of claim 2, wherein the capturing the feature point movement by the stereo vision system and performing image operations on the feature point to calculate a surface three-dimensional displacement field comprises:
and contacting the force or the object to be measured with the upper surface of the opaque coating, applying an external contact force, and acquiring an image of the characteristic layer by performing image acquisition or scanning by a stereoscopic vision system.
4. The method of claim 3, wherein the acquiring the feature point movement and performing image operations on the feature points by the stereo vision system to calculate a surface three-dimensional displacement field, further comprises:
performing frame-by-frame feature point matching according to the image of the feature layer, and performing three-dimensional reconstruction on the feature points of the feature layer to obtain three-dimensional coordinates of the speckle layer at different moments;
and subtracting the initial coordinate from the three-dimensional coordinate to obtain surface deformation fields at different moments.
5. The method of claim 4, wherein said solving elasto-mechanical equations from elastomer constitutive relations to obtain a stress distribution applied to an upper surface of said three-way contact stress characterization system comprises:
and solving the elastic mechanical equation or the finite element model by utilizing the preset constitutive model of the transparent elastomer and the surface deformation field to obtain the three-dimensional stress distribution applied to the surface of the transparent elastomer.
6. The utility model provides a three-dimensional contact stress characterization device based on stereovision, its characterized in that, wherein, three-dimensional contact stress characterization system is including being fixed in the transparent elastomer on the transparent support body, cover in the characteristic layer on the transparent elastomer, cover in opaque picture layer on the characteristic layer and catch and reconstruct the stereovision system of the displacement field information of characteristic, wherein, the device includes:
the deformation module is used for generating deformation by utilizing the contact of the upper surface of the transparent elastic body and an external object so as to move the characteristic points on the characteristic layer;
the acquisition module is used for acquiring the movement of the characteristic points through the stereoscopic vision system and carrying out image operation on the characteristic points to obtain a surface layer three-dimensional displacement field; and
and the characterization module is used for solving an elastic mechanical equation or a finite element model according to the constitutive relation of the elastomer to obtain the stress distribution applied to the upper surface of the three-way contact stress characterization system.
7. The apparatus of claim 6, wherein the deformation module is specifically configured to select a target calibration device according to the stereoscopic vision system, obtain internal and external parameters of the three-way contact stress characterization system through calibration measurement, place a feature layer covered with a speckle coating and a transparent elastomer of the opaque coating, and turn on a light source to adjust the stereoscopic vision system to focus on the feature layer to start image acquisition or scan imaging.
8. The apparatus of claim 7, wherein the acquisition module is specifically configured to contact a force or object to be measured with the upper surface of the opaque coating and apply an external contact force to acquire an image of the feature layer acquired or scanned by the stereoscopic vision system.
9. The apparatus of claim 8, wherein the acquisition module is further configured to perform frame-by-frame feature point matching according to the image of the feature layer, perform three-dimensional reconstruction on the feature points of the feature layer to obtain three-dimensional coordinates of the speckle layer at different time instants, and subtract the initial coordinates from the three-dimensional coordinates to obtain the deformation field of the surface layer at different time instants.
10. The apparatus according to claim 9, wherein the characterization module is specifically configured to obtain the three-dimensional stress distribution applied to the surface of the transparent elastic body by solving the elastic mechanical equation or by solving a finite element model using a preset constitutive model of the transparent elastic body and the surface deformation field.
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