Inflatable flexible visual tactile device and method for measuring surface topography of object

Abstract

The invention provides an inflatable flexible visual tactile device and method for measuring the surface topography of an object. The device comprises an inflatable flexible visual tactile sensor, a clamp and a support, and the inflatable flexible visual tactile sensor comprises a tactile sensing unit and a visual imaging unit; when the surface of an object is in contact with the sensor, the flexible thin film and the external reflecting layer in the tactile sensing unit deform and are attached to the surface of the object under the action of internal air pressure of the inflatable flexible visual tactile sensor, and the deformed flexible thin film is subjected to three-dimensional reconstruction by using a photometric stereo technology; therefore, reconstruction of all shapes of the surface of the object and real-time measurement of the size are realized. According to the device, a sealed inflatable structural design is adopted, skeleton support is omitted to expand the effective measurement range of the flexible film, and meanwhile, the flexible film is tightly attached to the surface of a measured object under the action of air pressure, so that accurate concave-convex feature information of the surface of the object is collected, and the reconstruction precision and the measurement precision of the complex surface morphology of the object are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical processing technology, and in particular to an inflatable flexible visual-tactile device and method for measuring the surface topography of an object. Background Art

[0002] With the rapid development of the manufacturing industry, the requirements for precision of mechanical equipment are constantly increasing. Whether the parameters such as the shape, size and surface quality of parts meet the design standards directly affects the accuracy and overall performance of the equipment. For example, in the field of automobile manufacturing, the surface roughness of engine parts will directly affect fuel efficiency and service life; in precision mechanical assembly, even a small change in surface texture may significantly affect the fit accuracy and motion performance of parts. Therefore, ensuring that part parameters meet standards is crucial to improving equipment performance, and how to accurately measure and verify is the key.

[0003] At present, the detection methods of parts in the industrial field are mainly divided into two categories: contact measurement and non-contact measurement. Contact measurement methods include coordinate measuring machines, surface roughness meters and profilometers. Although contact measurement methods have high accuracy, they generally have disadvantages such as slow detection speed and easy damage to the surface of parts. Non-contact measurement can be divided into active and passive types according to the different measurement signal sources. Active measurement methods include laser scanning methods, radar technology, etc., which rely on actively transmitted signals to obtain measurement data. Passive measurement methods are mainly based on image-based three-dimensional reconstruction methods, including monocular vision methods, stereo vision methods, photometric stereo methods, etc. Compared with active methods, passive methods can more effectively cope with various complex environments and have the advantages of lower cost and easier operation.

[0004] The visual tactile sensor based on photometric stereo has shown good practicality and economy in practical applications due to its small size, simple structure, low cost, and ability to accurately reconstruct the surface texture of parts. However, the contact surface of the elastic body used in the traditional GelSight visual tactile sensor based on photometric stereo algorithm is flat and has a small deformation. Although it can reconstruct the surface texture of the object, the flat elastic body cannot fit tightly with the depressions on the surface of the measured object, resulting in poor feature reconstruction in these areas, thus affecting the overall measurement accuracy of the parts. To overcome this problem, it is necessary to propose new methods and designs to enhance the degree of fit between the elastomer and the depressions on the surface of the object, improve the reconstruction accuracy of the complex surface morphology of the object, and realize the real-time and accurate reconstruction of the surface morphology details of the parts, thereby effectively improving the accuracy of the measurement of related parameters of the parts. Summary of the invention

[0005] According to the technical problems raised above, an inflatable flexible visual-tactile device and method for measuring the surface morphology of an object are provided. The device of the present invention adopts a sealed inflatable structural design, which can omit the skeleton support to expand the effective measurement range of the flexible film, and can also make the flexible film fit tightly with the surface of the object under the action of air pressure, so as to collect accurate information on the concave and convex features of the object surface, significantly improving the reconstruction accuracy of the surface morphology of the object and the overall performance of the sensor.

[0006] The technical means adopted by the present invention are as follows:

[0007] An inflatable flexible visual-tactile device for measuring the surface topography of an object comprises: an inflatable flexible visual-tactile sensor for collecting a topographic image of the surface of the object to be measured, a fixture for fixing the object to be measured, and a bracket for adjusting the height of the object to be measured and pressing the object to be measured on the surface of the inflatable flexible visual-tactile sensor for topographic measurement, the inflatable flexible visual-tactile sensor and the bracket being fixed on a base; the fixture is connected to the bracket through a connecting shaft; wherein:

[0008] The inflatable flexible visual-tactile sensor comprises a tactile sensing unit and a visual imaging unit, wherein:

[0009] The tactile sensing unit is provided with a reflective layer, a flexible film, a fixing ring, a one-way valve, a circular acrylic plate, a light shielding ring, a ring-shaped acrylic plate and a light shielding cylinder from top to bottom;

[0010] The visual imaging unit is provided with a transparent resin lamp cap, LED lamp beads, LED lamp ring, lamp ring base, camera light shielding tube, fixed top cover, fisheye lens, camera, fixed bottom plate and computer from top to bottom;

[0011] The tactile sensing unit and the visual imaging unit are connected via threads between the light-shielding cylinder and the camera light-shielding cylinder, and the components of the tactile sensing unit and the visual imaging unit are placed coaxially with the optical axis of the camera;

[0012] When the surface of the object to be measured contacts the inflatable flexible visual-tactile sensor, the flexible film and the external reflective layer are deformed and adhere to the surface of the object to be measured under the action of the internal air pressure of the inflatable flexible visual-tactile sensor. The computer uses photometric stereo technology to perform three-dimensional reconstruction of the deformed flexible film, thereby realizing the reconstruction of the entire surface morphology of the object to be measured and real-time measurement of its size.

[0013] Furthermore, the tactile sensing unit is sealed by epoxy resin, wherein:

[0014] Epoxy resin fixes the annular acrylic plate to the bottom of the shading cylinder to ensure that the bottom is sealed and stable; epoxy resin fills the gaps between the fixing ring, the circular acrylic plate, the shading ring, the annular acrylic plate and the shading cylinder; epoxy resin fills the gap between the one-way valve and the fixing ring, and uses a sealing film to perform secondary sealing on the interface to ensure the sealing of the tactile sensing unit after inflation.

[0015] Furthermore, in the tactile perception unit:

[0016] The one-way valve is connected to the fixing ring and is used to inflate and pressurize the tactile sensing unit. After the inflation is completed, the tactile sensing unit is in a completely sealed state;

[0017] The reflective layer, the flexible film and the fixed ring constitute a morphology feedback module, and the fixed ring is fixedly connected to the lower edges of the reflective layer and the flexible film; wherein:

[0018] The reflective layer is made by mixing titanium dioxide powder and silica gel in a certain proportion, and is evenly sprayed on the flexible film by connecting an airbrush to an air pump; it is used to receive light reflection from the light source, and at the same time improve the light-proofness of the flexible film, so as to avoid potential interference of ambient light on the tactile perception unit;

[0019] The flexible film is made of silica gel mixed with aluminum powder with a particle diameter of 50 μm, and is used for contact sensing of the object to be measured and external pressure.

[0020] Further, in the visual imaging unit:

[0021] A plurality of LED lamp beads are arranged on the upper surface of the LED light ring to provide light sources from different directions;

[0022] The transparent resin lamp cap covers the LED lamp beads, making the LED lamp beads illuminate more evenly;

[0023] The light ring base is used to fix the LED light ring to ensure that each LED lamp bead is on the same horizontal plane; the fixed top cover is used to connect the fisheye lens, camera and LED light ring;

[0024] The fisheye lens provides a 160° viewing angle, ensuring that the camera has a sufficient visual range for the deformation of the elastic body;

[0025] The camera is arranged at the center of the fixed base plate, and the optical axis of the camera is kept vertical;

[0026] The fixed bottom plate is used to provide support for the entire visual imaging unit;

[0027] The computer is used to control the camera to collect pictures.

[0028] Furthermore, there are four LED lamp beads, which are respectively fixed on the upper surface of the LED light ring. The colors of the four LED lamp beads are arranged in the order of red, green, blue and yellow; the angle between every two LED lamp beads is 90°, and each LED lamp bead forms an angle of 90° with the optical axis of the camera.

[0029] Furthermore, the fixed ring, the light-shielding cylindrical tube, the camera light-shielding tube, the fixed top cover and the fixed bottom plate constitute the outer shell of the inflatable flexible visual-tactile sensor.

[0030] Further, the clamp comprises: a tightening knob, a bolt connection ring, a secondary clamp, a solid pin, a main clamp and an anti-slip pad, wherein:

[0031] When fixing the object to be measured, the tightening knob is rotated, and the thread of the bolt connection ring enters the rotating tightening knob, thereby tightening the auxiliary clamp inward, reducing the distance between the auxiliary clamp and the main clamp, and thus clamping the object to be measured.

[0032] Furthermore, the bracket includes: a spur rack, a gear box, a ratchet, an axle pin, a pawl, a spur gear and a lifting knob, wherein:

[0033] After the object to be measured is clamped, press the surface of the object to be measured toward the topography feedback module, and rotate the lifting knob to a suitable height while pressing down. The ratchet and pawl have a self-locking function to prevent the fixture from sliding down.

[0034] After completing the measurement, push the pawl downward to release the self-locking function of the ratchet wheel, rotate the lifting knob to raise the object to be measured, and then push the pawl back to prevent the object from sliding down.

[0035] The present invention also provides a detection method based on the surface morphology of an object, which is implemented based on the inflatable flexible visual-tactile device for measuring the surface morphology of the object, comprising:

[0036] S1. Before measuring the surface morphology of the object to be measured, calibrate the camera:

[0037] Collect photos of the complete calibration plate in different postures, calculate the camera's intrinsic parameters, extrinsic parameters and distortion coefficients, and complete camera calibration;

[0038] S2. When measuring the surface morphology of an object, perform image acquisition:

[0039] When measuring the surface morphology of the object being measured, four LED lamp beads in different directions are lighted up respectively, and a photo is taken each time an LED lamp bead is lit up to collect images of the flexible film under different lighting positions;

[0040] S3, correcting and preprocessing the image collected in step S3:

[0041] Correct the image using the camera's intrinsic parameters and distortion coefficients obtained by camera calibration in step S2;

[0042] Preprocess the collected images, including noise removal, image alignment and image matching, to ensure the accuracy and consistency of the photo data;

[0043] S4. Perform three-dimensional reconstruction of the morphology of the flexible film to obtain a three-dimensional point cloud:

[0044] According to the image pre-processed in step S3, the three-dimensional reconstruction of the morphology of the flexible film is completed by photometric stereo technology to obtain a three-dimensional point cloud.

[0045] Compared with the prior art, the present invention has the following advantages:

[0046] 1. The present invention provides an inflatable flexible visual-tactile device for measuring the surface morphology of an object. The inflatable flexible visual-tactile sensor adopts a structural design of a flexible film plus a reflective layer. The device is sealed and then inflated and pressurized. The air pressure can inflate the flexible film to provide supporting strength. Therefore, the skeleton support can be omitted to expand the effective measurement range of the flexible film, thereby enhancing the applicability of the visual-tactile sensor.

[0047] 2. The present invention provides an inflatable flexible visual-tactile device for measuring the surface morphology of an object. Compared with the solid elastomer of the traditional visual-tactile sensor, the inflatable flexible visual-tactile sensor adopts an elastomer with a flexible film supported by air pressure, which solves the problem that the traditional elastomer cannot fit tightly with the undulations on the surface of the object to be measured, resulting in poor feature measurement results at the concave part of the object. Under the action of air pressure, the flexible film of the present invention can fit tightly with the surface of the object to be measured, thereby collecting accurate information on the concave and convex features of the object surface, and then using photometric stereo technology to perform three-dimensional reconstruction of the deformed flexible film, thereby achieving accurate reconstruction of the surface morphology of the object, and improving the details and accuracy of the reconstruction of the surface morphology of the object.

[0048] Based on the above reasons, the present invention can be widely promoted in the fields of parts measurement and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0050] Figure 1 It is a schematic diagram of the inflatable flexible visual-tactile device of the present invention.

[0051] Figure 2It is a cross-sectional schematic diagram of the inflatable flexible visual-tactile sensor of the present invention.

[0052] Figure 3 It is a schematic diagram of the tactile sensing unit in the inflatable flexible visual tactile sensor of the present invention.

[0053] Figure 4 It is a schematic diagram of the visual imaging unit in the inflatable flexible visual-tactile sensor of the present invention.

[0054] Figure 5 Schematic diagram of the clamp of the present invention.

[0055] Figure 6 Schematic diagram of the support of the present invention.

[0056] In the figure: 1. Inflatable flexible visual tactile sensor; 1-1. Reflective layer; 1-2. Flexible film; 1-3. Fixed ring; 1-4. One-way valve; 1-5. Round acrylic plate; 1-6. Shading ring; 1-7. Ring acrylic plate; 1-8. Shading cylinder; 1-9. Resin lamp cap; 1-10. LED lamp; 1-11. LED lamp ring; 1-12. Light ring base; 1-13. Camera shading cylinder; 1-14. Fixed top cover; 1-15 , fisheye lens; 1-16, camera; 1-17, fixed base plate; 1-18 computer; 2, clamp; 2-1, tightening knob; 2-2, bolt connecting ring; 2-3, auxiliary clamp; 2-4, solid pin; 2-5, main clamp; 2-6, anti-slip pad; 3, bracket; 3-1, spur rack; 3-2, gear box; 3-3, ratchet; 3-4, shaft pin; 3-5, pawl; 3-6, spur gear; 3-7, lifting knob; 4, base; 5, connecting shaft. DETAILED DESCRIPTION

[0057] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0058] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0059] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0060] Unless otherwise specifically stated, the relative arrangement of the parts and steps described in these embodiments, the numerical expressions and numerical values ​​do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to ordinary technicians in the relevant field may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be regarded as part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0061] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0062] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used here to describe the spatial positional relationship between a device or feature and other devices or features as shown in the figure. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figure. For example, if the device in the accompanying drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0063] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0064] like Figure 1 As shown, the present invention provides an inflatable flexible visual-tactile device for measuring the surface morphology of an object, comprising: an inflatable flexible visual-tactile sensor 1, a fixture 2 and a bracket 3, wherein the inflatable flexible visual-tactile sensor 1 and the bracket 3 are fixed on a base 4; the fixture 2 is connected to the bracket 3 through a connecting shaft 5;

[0065] in:

[0066] The inflatable flexible visual-tactile sensor 1 is used to collect the topographic image of the surface of the object being measured;

[0067] The fixture 2 is used to fix the object to be measured;

[0068] The support 3 is used to adjust the height of the object to be measured, and to press the object to be measured on the inflatable flexible visual tactile

[0069] The surface of sensor 1 is topographically measured.

[0070] When specifically implemented, as a preferred embodiment of the present invention, Figure 2 As shown, the inflatable flexible visual tactile sensor 1 includes a tactile perception unit and a visual imaging unit, wherein:

[0071] like Figure 3 As shown, the tactile sensing unit is provided with a reflective layer 1-1, a flexible film 1-2, a fixing ring 1-3, a one-way valve 1-4, a circular acrylic plate 1-5, a light shielding ring 1-6, a ring-shaped acrylic plate 1-7 and a light shielding cylinder 1-8 from top to bottom;

[0072] like Figure 4 As shown, the visual imaging unit is provided with a transparent resin lamp cap 1-9, an LED lamp bead 1-10, an LED lamp ring 1-11, a lamp ring base 1-12, a camera light shielding tube 1-13, a fixed top cover 1-14, a fisheye lens 1-15, a camera 1-16, a fixed bottom plate 1-17 and a computer 1-18 from top to bottom;

[0073] The tactile perception unit and the visual imaging unit are connected via threads between the light-shielding cylinder 1-8 and the camera light-shielding cylinder 1-13, and the components of the tactile perception unit and the visual imaging unit are placed coaxially with the optical axis of the camera;

[0074] When the surface of the object to be measured contacts the inflatable flexible visual-tactile sensor 1, the flexible film 1-2 and the external reflective layer 1-1 are deformed, and adhere to the surface of the object to be measured under the action of the internal air pressure of the inflatable flexible visual-tactile sensor 1. The deformed flexible film 1-2 is three-dimensionally reconstructed using photometric stereo technology, thereby realizing reconstruction of the entire surface morphology of the object to be measured and real-time measurement of its size.

[0075] The working principle of the inflatable flexible visual tactile sensor of the present invention is as follows:

[0076] Before using the inflatable flexible visual tactile sensor, the camera calibration is first performed, the tactile perception system is separated from the visual imaging system, and 20 images of the checkerboard calibration plate at different positions and postures are taken within the camera field of view. After completing the camera calibration, the tactile perception system and the visual imaging system are connected. When the sensor is used for the first time, the sensor needs to be inflated. The air pump is connected to the one-way valve 1-4 for inflation and pressurization. After the inflation is completed, the inflation tube is unplugged. The entire tactile perception unit is a closed structure. Select the part to be measured and reconstructed, and press the surface of the measured part vertically toward the flexible film 1-2. Under the action of air pressure, the flexible film 1-2 can fit closely with the surface of the measured object, so as to collect accurate information on the concave and convex features of the object surface, respectively light up 4 LED lamp beads 1-10 in different directions, take a photo every time an LED lamp bead 1-10 is lit, collect images of the flexible film 1-2 under different lighting positions, and then use the photometric stereo technology to perform three-dimensional reconstruction of the deformed flexible film 1-2, so as to achieve accurate reconstruction of the surface morphology of the object.

[0077] When implementing the invention, as a preferred embodiment of the invention, see Figure 3 , the tactile sensing unit is sealed by epoxy resin, wherein:

[0078] Epoxy resin fixes the annular acrylic plate 1-7 to the bottom of the shading cylinder 1-8 to ensure that the bottom is sealed and stable; epoxy resin fills the gaps between the fixing ring 1-3, the circular acrylic plate 1-5, the shading ring 1-6, the annular acrylic plate 1-7 and the shading cylinder 1-8; epoxy resin fills the gap between the one-way valve 1-4 and the fixing ring 1-3, and uses a sealing film to perform secondary sealing on the interface to ensure the sealing of the tactile sensing unit after inflation.

[0079] When implementing the invention, as a preferred embodiment of the invention, see Figure 3 , in the tactile perception unit:

[0080] The one-way valve 1-4 is connected to the fixing ring 1-3 and is used to inflate and pressurize the tactile sensing unit. After the inflation is completed, the tactile sensing unit is in a completely sealed state;

[0081] The reflective layer 1-1, the flexible film 1-2 and the fixed ring 1-3 constitute a morphology feedback module, and the fixed ring 1-3 is fixedly connected to the lower edges of the reflective layer 1-1 and the flexible film 1-2 to provide rigid support so that it can be connected to the shading cylinder 1-8, wherein:

[0082] The reflective layer 1-1 is made by mixing titanium dioxide powder and silica gel in a certain proportion, and is evenly sprayed on the flexible film 1-2 by connecting an airbrush to an air pump; it is used to receive light reflection from the light source, and at the same time improve the light-proof property of the flexible film, so as to avoid potential interference of ambient light on the tactile sensing unit;

[0083] The flexible film 1-2 is made of silica gel mixed with aluminum powder with a particle diameter of 50 μm, and is used for contact sensing of the object to be measured and external pressure.

[0084] When implementing the invention, as a preferred embodiment of the invention, see Figure 4 , in the visual imaging unit:

[0085] A plurality of LED lamp beads 1-10 are arranged on the upper surface of the LED light ring 1-11, which are used to provide light sources from different directions; a transparent resin lamp cap 1-9 covers the LED lamp beads 1-10, so that the LED lamp beads 1-10 are illuminated more evenly; the light ring base 1-12 is used to fix the LED light ring 1-11, ensuring that each LED lamp bead 1-10 is on the same horizontal plane; the fixed top cover 1-14 is used to connect the fisheye lens 1-15, the camera 1-16 and the LED light ring 1-11; the fisheye lens 1-15 provides a 160° viewing angle, ensuring that the camera 1-16 has a sufficient visual range for the deformation of the elastic body; the camera 1-16 is arranged in the center of the fixed base plate 1-17, and the optical axis of the camera 1-16 remains vertical; the fixed base plate 1-17 is used to provide support for the entire visual imaging unit; the computer 1-18 is used to control the camera 1-16 to collect pictures.

[0086] In specific implementation, as a preferred embodiment of the present invention, four LED lamp beads 1-10 are provided and are respectively fixed on the upper surface of the LED light ring 9. The colors of the four LED lamp beads 1-10 are arranged in the order of red, green, blue, and yellow; the angle between every two LED lamp beads 1-10 is 90°, and each LED lamp bead 1-10 is at an angle of 90° with the optical axis of the camera 1-16.

[0087] In specific implementation, as a preferred embodiment of the present invention, the fixed ring 1-3, the light-shielding cylindrical tube 1-8, the camera light-shielding tube 1-13, the fixed top cover 1-14 and the fixed bottom plate 1-17 constitute the outer shell of the inflatable flexible visual-tactile sensor 1.

[0088] When specifically implemented, as a preferred embodiment of the present invention, Figure 5 As shown, the clamp 2 includes: a tightening knob 2-1, a bolt connection ring 2-2, a secondary clamp 2-3, a solid pin 2-4, a main clamp 2-5 and an anti-slip pad 2-6, wherein: when fixing the object to be measured, the tightening knob 2-1 is rotated, and the thread of the bolt connection ring 2-2 enters the rotating tightening knob 2-1, thereby tightening the secondary clamp 2-3 inward, and the distance between the secondary clamp 2-3 and the main clamp 2-5 is reduced, thereby clamping the object to be measured.

[0089] When specifically implemented, as a preferred embodiment of the present invention, Figure 6As shown, the bracket 3 includes: a spur rack 3-1, a gear box 3-2, a ratchet 3-3, a shaft pin 3-4, a pawl 3-5, a spur gear 3-6 and a lifting knob 3-7, wherein: after the object to be measured is clamped, the surface of the object to be measured is pressed toward the morphology feedback module, and the lifting knob 3-7 is rotated to a suitable height while pressing downward, and the ratchet 3-3 and the pawl 3-5 have a self-locking function to prevent the fixture 2 from sliding down; after the measurement is completed, the pawl 3-5 is pushed downward to release the self-locking of the ratchet 3-3, and the lifting knob 3-7 is rotated to lift the object to be measured and then the pawl 3-5 is pushed back to prevent the object to be measured from sliding down.

[0090] The embodiment of the present invention further provides a detection method based on the surface morphology of an object, which is implemented based on the inflatable flexible visual-tactile device for measuring the surface morphology of the object, comprising:

[0091] S1. Before measuring the surface morphology of the object to be measured, calibrate the cameras 1-16:

[0092] Collect at least 20 photos of the complete calibration plate in different postures, calculate the intrinsic parameters, extrinsic parameters and distortion coefficients of cameras 1-16, and complete the calibration of cameras 1-16;

[0093] S2. When measuring the surface morphology of an object, perform image acquisition:

[0094] When measuring the surface morphology of the object to be measured, four LED lamp beads 1-10 in different directions are lighted respectively, and a photo is taken each time an LED lamp bead 1-10 is lighted to collect images of the flexible film 1-2 under different lighting positions;

[0095] S3, correcting and preprocessing the image collected in step S3:

[0096] Correct the image using the intrinsic parameters and distortion coefficients of cameras 1-16 obtained by camera calibration in step S2;

[0097] Preprocess the collected images, including noise removal, image alignment and image matching, to ensure the accuracy and consistency of the photo data;

[0098] S4, perform three-dimensional reconstruction of the morphology of the flexible film 1-2 to obtain a three-dimensional point cloud:

[0099] According to the image after the preprocessing in step S3, the three-dimensional reconstruction of the morphology of the flexible film 1-2 is completed by photometric stereo technology to obtain a three-dimensional point cloud.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An inflatable flexible visual-tactile device for measuring the surface topography of an object. It is characterized in that include: An inflatable flexible visual-tactile sensor (1) for collecting a topographic image of a surface of an object to be measured, a fixture (2) for fixing the object to be measured, and a bracket (3) for adjusting the height of the object to be measured and pressing the object to be measured on the surface of the inflatable flexible visual-tactile sensor (1) for topographic measurement. The inflatable flexible visual-tactile sensor (1) and the bracket (3) are fixed on a base (4); the fixture (2) is connected to the bracket (3) via a connecting shaft (5); wherein: The inflatable flexible visual-tactile sensor (1) comprises a tactile sensing unit and a visual imaging unit, wherein: The tactile sensing unit is provided with a reflective layer (1-1), a flexible film (1-2), a fixing ring (1-3), a one-way valve (1-4), a circular acrylic plate (1-5), a light shielding ring (1-6), a ring-shaped acrylic plate (1-7) and a light shielding cylinder (1-8) from top to bottom; The visual imaging unit is provided with a transparent resin lamp cap (1-9), an LED lamp bead (1-10), an LED lamp ring (1-11), a lamp ring base (1-12), a camera light shielding tube (1-13), a fixed top cover (1-14), a fisheye lens (1-15), a camera (1-16), a fixed bottom plate (1-17) and a computer (1-18) from top to bottom; The tactile perception unit and the visual imaging unit are connected via threads between the light-shielding cylindrical tube (1-8) and the camera light-shielding tube (1-13), and the components of the tactile perception unit and the visual imaging unit are placed coaxially with the camera optical axis; When the surface of the object to be measured contacts the inflatable flexible visual tactile sensor (1), the flexible film (1-2) and the external reflective layer (1-1) are deformed and tightly adhere to the surface of the object to be measured under the action of the internal air pressure of the inflatable flexible visual tactile sensor (1), thereby collecting accurate information on the concave and convex features of the object surface. Then, the deformed flexible film (1-2) is three-dimensionally reconstructed using photometric stereo technology, thereby achieving reconstruction of the entire morphology of the surface of the object to be measured and real-time measurement of its dimensions.

2. An inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that The tactile sensing unit is sealed by epoxy resin, wherein: The epoxy resin fixes the annular acrylic plate (1-7) to the bottom of the light-shielding cylindrical tube (1-8) to ensure that the bottom is sealed and stable; the epoxy resin fills the gaps between the fixing ring (1-3), the circular acrylic plate (1-5), the light-shielding ring (1-6), the annular acrylic plate (1-7) and the light-shielding cylindrical tube (1-8); the epoxy resin fills the gap between the one-way valve (1-4) and the fixing ring (1-3), and a sealing film is used to perform a secondary seal on the interface to ensure the sealing of the tactile sensing unit after inflation.

3. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that In the tactile sensing unit: The one-way valve (1-4) is connected to the fixing ring (1-3) and is used to inflate and pressurize the tactile sensing unit. After the inflation is completed, the tactile sensing unit is in a completely sealed state; The reflective layer (1-1), the flexible film (1-2) and the fixed ring (1-3) form a morphology feedback module, and the fixed ring (1-3) is fixedly connected to the lower edges of the reflective layer (1-1) and the flexible film (1-2); wherein: The reflective layer (1-1) is formed by mixing titanium dioxide powder and silica gel in a certain proportion, and is evenly sprayed on the flexible film (1-2) by using a spray gun connected to an air pump; it is used to receive light reflection from the light source, while improving the light-proofness of the flexible film, and avoiding potential interference of ambient light on the tactile perception unit; The flexible film (1-2) is made of silica gel mixed with aluminum powder with a particle diameter of 50 μm and is used for contact sensing of the object to be measured and external pressure.

4. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that In the visual imaging unit: A plurality of LED lamp beads (1-10) are arranged on the upper surface of the LED lamp ring (1-11) for providing light sources from different directions; The transparent resin lamp cap (1-9) covers the LED lamp bead (1-10), so that the LED lamp bead (1-10) can illuminate more evenly; The light ring base (1-12) is used to fix the LED light ring (1-11) to ensure that each LED lamp bead (1-10) is on the same horizontal plane; the fixed top cover (1-14) is used to connect the fisheye lens (1-15), the camera (1-16) and the LED light ring (1-11); The fisheye lens (1-15) provides a 160° viewing angle, ensuring that the camera (1-16) has a sufficient viewing range for the deformation of the flexible film; The camera (1-16) is arranged at the center of the fixed base plate (1-17), and the optical axis of the camera (1-16) is kept vertical; The fixed base plate (1-17) is used to provide support for the entire visual imaging unit; The computer (1-18) is used to control the camera (1-16) to collect pictures.

5. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 4, It is characterized in that Four LED lamp beads (1-10) are provided and are respectively fixed on the upper surface of the LED lamp ring (9); the colors of the four LED lamp beads (1-10) are arranged in the order of red, green, blue and yellow; the angle between every two LED lamp beads (1-10) is 90°, and each LED lamp bead (1-10) forms an angle of 90° with the optical axis of the camera (1-16).

6. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that The fixed ring (1-3), the light-shielding cylindrical tube (1-8), the camera light-shielding tube (1-13), the fixed top cover (1-14) and the fixed bottom plate (1-17) form the outer shell of the inflatable flexible visual-tactile sensor (1).

7. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that The clamp (2) comprises: a tightening knob (2-1), a bolt connection ring (2-2), a secondary clamp (2-3), a solid pin (2-4), a main clamp (2-5) and an anti-slip pad (2-6), wherein: When fixing the object to be measured, the tightening knob (2-1) is rotated, and the thread of the bolt connection ring (2-2) enters the rotating tightening knob (2-1), thereby tightening the auxiliary clamp (2-3) inward, reducing the distance between the auxiliary clamp (2-3) and the main clamp (2-5), and thus clamping the object to be measured.

8. The inflatable flexible visual-tactile device for measuring the surface topography of an object according to claim 1, It is characterized in that The bracket (3) comprises: a spur rack (3-1), a gear box (3-2), a ratchet (3-3), an axle pin (3-4), a ratchet pawl (3-5), a spur gear (3-6) and a lifting knob (3-7), wherein: After the object to be measured is clamped, the surface of the object to be measured is pressed against the shape feedback module, and the lifting knob (3-7) is rotated to a suitable height while pressing downward, and the ratchet (3-3) and the pawl (3-5) have a self-locking function to prevent the clamp (2) from sliding down; After the measurement is completed, the ratchet (3-5) is pushed downward to release the self-locking of the ratchet wheel (3-3), and the lifting knob (3-7) is rotated to raise the object to be measured and then the ratchet (3-5) is pushed back to prevent the object to be measured from sliding down.

9. A method for detecting the surface topography of an object implemented by the inflatable flexible visual-tactile device for measuring the surface topography of an object according to any one of claims 1 to 8, It is characterized in that include: S1. Before measuring the surface morphology of the object to be measured, calibrate the camera (1-16): Collect photos of the complete calibration plate in different postures, calculate the intrinsic parameters, extrinsic parameters and distortion coefficients of the camera (1-16), and complete the calibration of the camera (1-16); S2. When measuring the surface morphology of an object, perform image acquisition: When measuring the surface morphology of the object to be measured, four LED lamp beads (1-10) are lighted in different directions respectively, and a photo is taken each time an LED lamp bead (1-10) is lit to collect images of the flexible film (1-2) under different lighting positions; S3, correcting and preprocessing the image collected in step S3: Correcting the image using the intrinsic parameters and distortion coefficients of the camera (1-16) obtained by camera calibration in step S2; Preprocess the collected images, including noise removal, image alignment and image matching, to ensure the accuracy and consistency of the photo data; S4. Perform three-dimensional reconstruction of the morphology of the flexible film (1-2) to obtain a three-dimensional point cloud: According to the image after preprocessing in step S3, the three-dimensional reconstruction of the morphology of the flexible film (1-2) is completed by photometric stereo technology to obtain a three-dimensional point cloud.

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