An inflatable flexible tactile device and method for measuring the surface topography of an object

Abstract

The application provides an inflatable flexible visual-tactile device and method for measuring surface topography of an object. The device comprises an inflatable flexible visual-tactile sensor, a clamp and a support, the inflatable flexible visual-tactile sensor comprises a tactile perception unit and a visual imaging unit; when the surface of the object contacts the sensor, the flexible film and the external reflective layer in the tactile perception unit are deformed, and are attached to the surface of the object under the action of the internal air pressure of the inflatable flexible visual-tactile sensor; the deformed flexible film is reconstructed in three dimensions by using photometric stereo technology, so that the reconstruction of the whole surface topography of the object and the real-time measurement of the size are realized. The device adopts a sealed inflatable structure design, omits the skeleton support to expand the effective measurement range of the flexible film, and simultaneously makes the flexible film closely attached to the surface of the measured object under the action of the air pressure, so that the accurate surface concave-convex feature information of the object is collected, and the reconstruction accuracy and the measurement accuracy of the complex surface topography of the object are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machining, in particular, especially relates to a flexible pneumatic tactile device and method for measuring the surface topography of an object. BACKGROUND

[0002] With the rapid development of manufacturing industry, the precision requirement of mechanical equipment is continuously improved. Whether the shape, size and surface quality of the parts meet the design standard directly affects the precision and overall performance of the equipment. For example, in the field of automobile manufacturing, the surface roughness of engine parts will directly affect the fuel efficiency and service life; in precision mechanical assembly, even a slight change in surface texture can significantly affect the fitting accuracy and movement performance of the parts. Therefore, ensuring that the part parameters meet the standard is crucial to improve the performance of the equipment, and how to accurately measure and verify is the key.

[0003] Currently, the detection methods of parts in the industrial field mainly include contact measurement and non-contact measurement. The contact measurement method includes coordinate measuring machine, surface roughness meter and profilometer, etc. Although the contact measurement method has high precision, it has the disadvantages of slow detection speed and easy damage to the surface of the parts. Non-contact measurement can be divided into active and passive according to different measurement signal sources. Active measurement methods include laser scanning method, radar technology, etc., which rely on actively emitted signals to obtain measurement data. Passive measurement methods are mainly based on image-based three-dimensional reconstruction methods, including monocular vision method, stereo vision method, photometric stereo method, etc. Compared with active type, passive type can effectively cope with various complex environments, has the advantages of lower cost and more convenient operation.

[0004] The photometric stereo-based visual tactile sensor has good practicality and economy in actual application because of its small sensor volume, simple structure, low cost and accurate reconstruction of part surface texture. However, the traditional GelSight visual tactile sensor based on photometric stereo algorithm uses a flat elastic contact surface with small deformation, which can reconstruct the surface texture of the object, but the flat elastic body cannot closely fit the concave parts of the measured object surface, resulting in poor feature reconstruction effect in these areas, thereby affecting the overall measurement accuracy of the parts. To overcome this problem, it is necessary to propose new methods and designs to enhance the fitting degree of the elastic body to the concave parts of the object surface, improve the reconstruction accuracy of the complex surface topography of the object, realize the real-time and accurate reconstruction of the surface topography details of the parts, and effectively improve the accuracy of the measurement of the related parameters of the parts. SUMMARY

[0005] According to the technical problem proposed above, the application provides an inflatable flexible visual tactile device and method for measuring the surface topography of an object. The device of the application adopts a sealed inflatable structure design, which can omit the skeleton support to expand the effective measurement range of the flexible film, and also enable the flexible film to closely adhere to the surface of the measured object under the action of air pressure, so as to collect accurate information of the concave-convex features of the object surface, and significantly improve the reconstruction accuracy of the surface topography of the object and the overall performance of the sensor.

[0006] The application adopts the following technical means:

[0007] An inflatable flexible visual tactile device for measuring the surface topography of an object, comprising: an inflatable flexible visual tactile sensor for collecting the topography image of the surface of the measured object, a clamp for fixing the measured object, and a support for adjusting the height of the measured object to press the measured object on the surface of the inflatable flexible visual tactile sensor for topography measurement, the inflatable flexible visual tactile sensor and the support being fixed on a base; the clamp is connected to the support through a connecting shaft; wherein:

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

[0009] The tactile perception unit is provided with, from top to bottom, a reflective layer, a flexible film, a fixed ring, a one-way valve, a circular acrylic plate, a light shielding ring, an annular acrylic plate, and a light shielding cylindrical tube;

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

[0011] The tactile perception unit and the visual imaging unit are connected through the threads between the light shielding cylindrical tube and the camera light shielding cylinder, and the components of the tactile perception unit and the visual imaging unit are coaxially arranged with the camera optical axis;

[0012] When the surface of the measured object contacts the inflatable flexible visual tactile sensor, the flexible film and the external reflective layer are deformed, and are closely adhered to the surface of the measured object under the action of the air pressure inside the inflatable flexible visual tactile sensor, the computer uses photometric stereo technology to perform three-dimensional reconstruction on the deformed flexible film, and realizes the reconstruction of the entire surface topography of the measured object and the real-time measurement of the size.

[0013] Further, the tactile perception unit is sealed by epoxy resin, wherein:

[0014] Epoxy resin is used to fix the annular acrylic plate at the bottom of the light-shielding cylinder to ensure the bottom is sealed and stable; the epoxy resin is used to fill the gaps between the fixing ring, the circular acrylic plate, the light-shielding ring, the annular acrylic plate and the light-shielding cylinder; the epoxy resin is used to fill the gap between the one-way valve and the fixing ring, and the sealing film is used to seal the interface again to ensure the sealing of the touch perception unit after inflation.

[0015] Further, in the touch perception unit:

[0016] The one-way valve is connected with the fixing ring, and is used for inflating and pressurizing the touch perception unit, and the touch perception unit is in a completely sealed state after inflation is completed;

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

[0018] The reflective layer is a mixture of titanium dioxide powder and silica gel in a certain proportion, and is uniformly sprayed on the flexible film after being connected with the air pump by a spray pen; it is used to reflect the light from the light source and improve the light tightness of the flexible film, avoiding potential interference of ambient light on the touch perception unit;

[0019] The flexible film is made of silica gel mixed with aluminum powder with a particle diameter of 50μm, and is used to contact the measured object 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 ring, which are used to provide light sources from different directions;

[0022] The transparent resin lamp cap covers the LED lamp beads, so that the light of the LED lamp beads is more uniform;

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

[0024] The fisheye lens provides a 160° viewing angle to ensure that the camera has a sufficient visual range for the deformation of the elastomer;

[0025] The camera is arranged at the center of the fixed bottom 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] Further, the LED lamp beads are arranged four, and are fixed on the upper surface of the LED lamp ring, the colors of the four LED lamp beads are arranged in the order of red, green, blue and yellow, the included angle between every two LED lamp beads is 90 DEG, and the included angle between every LED lamp bead and the optical axis of the camera is 90 DEG.

[0029] Further, the fixing ring, the light shielding cylinder, the camera light shielding cylinder, the fixing top cover and the fixing bottom plate constitute the shell of the inflatable flexible visual tactile sensor.

[0030] Further, the clamp comprises a fastening knob, a screw connecting ring, a secondary clamp, a solid pin, a primary clamp and an antiskid pad, wherein:

[0031] When the measured object is fixed, the fastening knob is rotated, the screw thread of the screw connecting ring enters the fastening knob, thereby the secondary clamp is tightened inward, the distance between the secondary clamp and the primary clamp is reduced, and the measured object is clamped.

[0032] Further, the support comprises a straight rack, a gear box, a ratchet wheel, a shaft pin, a pawl, a straight gear and a lifting knob, wherein:

[0033] After the measured object is clamped, the surface of the measured object is pressed to the topographic feedback module, the lifting knob is rotated to a suitable height when being pressed downward, the ratchet wheel and the pawl have a self-locking function, and the clamp is prevented from sliding downward;

[0034] After the measurement is completed, the pawl is pushed downward to release the self-locking of the ratchet wheel, the measured object is lifted by rotating the lifting knob, and then the pawl is pushed back to prevent the measured object from sliding downward.

[0035] The application also provides an object surface topography based detection method realized by the inflatable flexible visual tactile device based on the object surface topography, comprising:

[0036] S1, before measuring the surface topography of the measured object, the camera is calibrated:

[0037] Complete calibration plate photos under different postures are collected, the intrinsic parameters, extrinsic parameters and distortion coefficients of the camera are calculated, and the camera calibration is completed;

[0038] S2, when measuring the surface topography of the object, image acquisition is performed:

[0039] When measuring the surface topography of the measured object, four LED lamp beads in different directions are lit respectively, one photo is taken for each lit LED lamp bead, and the images of the flexible film under different light positions are collected;

[0040] S3, the images collected in step S3 are corrected and pretreated:

[0041] The inner parameter and distortion coefficient of the camera obtained by the camera calibration in step S2 are used to correct the image;

[0042] The collected image is preprocessed, including noise removal, image alignment and image matching, to ensure the accuracy and consistency of the photo data.

[0043] S4, three-dimensional reconstruction of the topography of the flexible film is performed to obtain a three-dimensional point cloud:

[0044] According to the image after the preprocessing in step S3, three-dimensional reconstruction of the topography 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 application has the following advantages:

[0046] 1. The inflatable flexible visual tactile device for measuring the surface topography of an object provided by the present application adopts a structure design of a flexible film plus a reflective layer, and after sealing treatment of the device, inflation and pressurization, the air pressure can inflate the flexible film to provide support strength, so that the skeleton support can be omitted to expand the effective measurement range of the flexible film, and the applicability of the visual tactile sensor is enhanced.

[0047] 2. The inflatable flexible visual tactile device for measuring the surface topography of an object provided by the present application adopts an elastic body supporting the flexible film by air pressure, compared with the solid elastic body of the conventional visual tactile sensor, which solves the problem that the conventional elastic body cannot closely adhere to the undulations on the surface of the measured object, so that the measurement result of the features of the concave part of the object is not good. The flexible film of the present application can closely adhere to the surface of the measured object under the action of air pressure, so that accurate surface feature information of the object is collected, and then photometric stereo technology is used to perform three-dimensional reconstruction of the deformed flexible film, so that accurate reconstruction of the surface topography of the object is realized, and the details and accuracy of the reconstruction of the surface topography of the object are improved.

[0048] Based on the above reasons, the present application can be widely popularized in the field of part measurement. BRIEF DESCRIPTION OF DRAWINGS

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

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

[0051] Figure 2The cross section schematic diagram of the inflatable flexible visual-tactile sensor of the present application.

[0052] Figure 3 The schematic diagram of the tactile sensing unit in the inflatable flexible visual-tactile sensor of the present application.

[0053] Figure 4 The schematic diagram of the visual imaging unit in the inflatable flexible visual-tactile sensor of the present application.

[0054] Figure 5 The schematic diagram of the clamp of the present application.

[0055] Figure 6 The schematic diagram of the support of the present application.

[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, circular acrylic plate; 1-6, light shielding ring; 1-7, annular acrylic plate; 1-8, light shielding cylindrical tube; 1-9, resin lamp cap; 1-10, LED lamp; 1-11, LED lamp ring; 1-12, lamp ring base; 1-13, camera light shielding cylinder; 1-14, fixed top cover; 1-15, fisheye lens; 1-16, camera; 1-17, fixed bottom plate; 1-18, computer; 2, clamp; 2-1, fastening knob; 2-2, bolted ring; 2-3, sub clamp; 2-4, solid pin; 2-5, main clamp; 2-6, non-slip pad; 3, support; 3-1, straight rack; 3-2, gear box; 3-3, ratchet; 3-4, shaft pin; 3-5, pawl; 3-6, straight gear; 3-7, lifting knob; 4, base; 5, connecting shaft. DETAILED DESCRIPTION

[0057] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application 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 application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. The description of the at least one exemplary embodiment is actually only illustrative, but not as any limitation on the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0059] It is to be understood that the terms so far as the grammar used herein is concerned are to be interpreted in their dictionary meanings and are not to be interpreted in the context of legal terms unless so explicitly stated. It is also to be understood that the terminology and description provided above are for the purpose of simplifying the present disclosure and the invention, and are not intended to limit the scope of the application of the present invention, and the use of such terminology, and description is understood to also cover any technical equivalents for the subject matter covered. It is also to be understood that the terminology and description provided above are for the purpose of simplifying the present disclosure and the invention, and are not intended to limit the scope of the application of the present invention, and the use of such terminology, and description is understood to also cover any technical equivalents for the subject matter covered.

[0060] The relative arrangement of parts and steps, numerical expressions, and numerical values set forth in the examples are not intended to limit the scope of the application unless specifically so stated. It is also to be understood that the drawings are not necessarily drawn to scale and that the dimensions of the various parts shown in the drawings are intended to be illustrative only and not limiting of the scope of the application. Techniques, methods, and apparatus known to those of ordinary skill are not discussed in detail but can be employed with the systems and methods described herein. All examples shown and discussed herein are intended to be examples only and are not intended to limit the scope of the application. Thus, other examples of the exemplary embodiments can have different values. It is noted that like numbers and letters on the figures identify like parts throughout the several views, and that the use of the same or similar numbers and letters in different figures indicates similar or identical elements.

[0061] In the description of the present application, it is to be understood that the orientation or positional relationships indicated by terms such as "front", "back", "upper", "lower", "left", "right", "horizontal", "vertical", "top", "bottom", and the like are based on the orientation or positional relationships shown in the drawings, and are used only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be construed as limiting the scope of protection of the present application. The orientation terms "inner", "outer" refer to the inner and outer relative to the outline of the components themselves.

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

[0063] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this 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 clamp 2, and a bracket 3, wherein the inflatable flexible visual-tactile sensor 1 and the bracket 3 are fixed on a base 4; the clamp 2 is connected to the bracket 3 via a connecting shaft 5;

[0065] in:

[0066] The inflatable flexible visual-tactile sensor 1 is used to acquire morphological images of the surface of the object being measured.

[0067] The clamp 2 is used to fix the object being measured;

[0068] The bracket 3 is used to adjust the height of the object being tested and to press the object against the inflatable flexible visual-tactile sensor.

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

[0070] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 As shown, the inflatable flexible visual-tactile sensor 1 includes a tactile sensing 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, an annular acrylic plate 1-7, and a light-shielding cylindrical tube 1-8 from top to bottom.

[0072] As shown in Figure 4 , the visual imaging unit is provided from top to bottom 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 cylinder 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, respectively;

[0073] The tactile perception unit and the visual imaging unit are connected through threads between the light-shielding cylindrical 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 coaxially arranged with the camera optical axis;

[0074] When the surface of the measured object contacts the inflatable flexible visual tactile sensor 1, the flexible film 1-2 and the external reflection layer 1-1 are deformed and are attached to the surface of the measured object under the action of the internal air pressure of the inflatable flexible visual tactile sensor 1, and the deformed flexible film 1-2 is reconstructed in three dimensions by using photometric stereo technology, so as to realize the reconstruction of the entire surface topography of the measured object and the real-time measurement of the size.

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

[0076] Before use, the camera is calibrated, the tactile perception system and the visual imaging system are separated, 20 images of the checkerboard calibration board in different positions and postures are shot in the camera field of view, and after the camera calibration is completed, 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 with the one-way valve 1-4 for inflation and pressurization, the inflation pipe is pulled out after the inflation is completed, and the entire tactile perception unit is a closed structure. Select the part to be measured and reconstructed, press the surface of the measured part vertically to the flexible film 1-2, the flexible film 1-2 can be closely attached to the surface of the measured object under the action of the air pressure, so as to collect accurate object surface concave-convex feature information, light up four LED lamp beads 1-10 in different directions respectively, shoot a photo for each LED lamp bead 1-10, collect the images of the flexible film 1-2 under different light positions, and then use photometric stereo technology to reconstruct the deformed flexible film 1-2 in three dimensions, so as to realize the accurate reconstruction of the surface topography of the object.

[0077] In specific implementation, as a preferred embodiment of the present application, continuing to refer to Figure 3 , the tactile perception unit is sealed by epoxy resin, wherein:

[0078] Epoxy resin will be fixed in the light ring acrylic plate 1-7 1-8 bottom of the cylinder, to ensure the bottom of the seal and stable; epoxy resin filling fixed ring 1-3, 1-5, 1-6, 1-7 and light circular acrylic plate between the cylinder 1-8 connection gap; epoxy resin filling one-way valve 1-4 and fixed ring 1-3 between the gap, and the use of sealing film interface to the second sealing, to ensure the tactile perception unit after inflation seal.

[0079] In particular, as a preferred embodiment of the present application, continue to refer to Figure 3 In the tactile perception unit:

[0080] The one-way valve 1-4 and fixed ring 1-3 connection, for the tactile perception unit inflation pressurization process, after the completion of the inflation of the tactile perception unit is completely sealed state;

[0081] The reflective layer 1-1, flexible film 1-2 and fixed ring 1-3 composition topography feedback module, fixed ring 1-3 and the reflective layer 1-1 and flexible film 1-2 lower edge fixed connection, provide rigid support, so that it can be connected with the light cylinder 1-8 1-8, wherein:

[0082] The reflective layer 1-1 is a mixture of titanium dioxide powder and silica gel in a certain proportion, and is sprayed on the flexible film 1-2 after connecting the air pump with the spray pen; to receive light reflection from the light source, while improving the light tightness of the flexible film, avoiding potential interference of ambient light on the tactile perception unit;

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

[0084] In particular, as a preferred embodiment of the present application, continue to refer to Figure 4 In the visual imaging unit:

[0085] The LED lamp ring 1-11 is provided with a plurality of LED lamp beads 1-10 on the upper surface for providing light sources from different directions; the transparent resin lamp cap 1-9 covers the LED lamp beads 1-10 to make the light of the LED lamp beads 1-10 more uniform; the lamp ring base 1-12 is used for fixing the LED lamp 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 for connecting the fisheye lens 1-15, the camera 1-16 and the LED lamp ring 1-11; the fisheye lens 1-15 provides a 160° viewing angle to ensure that the camera 1-16 has sufficient visual range for the deformation of the elastomer; the camera 1-16 is arranged in the center of the fixed bottom plate 1-17, and the optical axis of the camera 1-16 remains vertical; the fixed bottom plate 1-17 is used to provide support for the entire visual imaging unit; and 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 application, the LED lamp beads 1-10 are provided with four, 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 included angle between every two LED lamp beads 1-10 is 90°, and the included angle between each LED lamp bead 1-10 and the optical axis of the camera 1-16 is 90°.

[0087] In specific implementation, as a preferred embodiment of the present application, 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 shell of the inflatable flexible visual tactile sensor 1.

[0088] In specific implementation, as a preferred embodiment of the present application, as shown in Figure 5 The clamp 2 includes a fastening knob 2-1, a bolted ring 2-2, a secondary clamp 2-3, a solid pin 2-4, a primary clamp 2-5 and an anti-skid pad 2-6, wherein: when fixing the measured object, the fastening knob 2-1 is rotated, the threads of the bolted ring 2-2 enter the fastening knob 2-1, thereby tightening the secondary clamp 2-3 inward, the distance between the secondary clamp 2-3 and the primary clamp 2-5 is reduced, thereby clamping the measured object.

[0089] In specific implementation, as a preferred embodiment of the present application, as shown in Figure 6As shown, the support 3 comprises: a straight rack 3-1, a gear box 3-2, a ratchet wheel 3-3, a shaft pin 3-4, a pawl 3-5, a straight gear 3-6 and a lifting knob 3-7, wherein: after clamping the measured object, the surface of the measured object is pressed to the topography feedback module, the lifting knob 3-7 is rotated to the appropriate height when pressed downward, the ratchet wheel 3-3 and the pawl 3-5 have self-locking function to prevent the clamp 2 from sliding downward; after the measurement is completed, the pawl 3-5 is pushed downward, the self-locking of the ratchet wheel 3-3 is released, the lifting knob 3-7 is rotated to lift the measured object, and then the pawl 3-5 is pushed back to prevent the measured object from sliding downward.

[0090] The embodiment of the present application also provides a detection method based on the surface topography of an object, which is realized by the inflatable flexible tactile device based on the surface topography of the object, and the method comprises the following steps:

[0091] S1, before measuring the surface topography of the measured object, calibrate the camera 1-16:

[0092] At least 20 complete calibration board photos under different postures are collected, the intrinsic parameters, extrinsic parameters and distortion coefficients of the camera 1-16 are calculated, and the calibration of the camera 1-16 is completed;

[0093] S2, when measuring the surface topography of the object, image acquisition is performed:

[0094] When measuring the surface topography of the measured object, four LED lamp beads 1-10 in different directions are lit respectively, one photo is taken for each time of lighting one LED lamp bead 1-10, and the images of the flexible film 1-2 under different light positions are collected;

[0095] S3, correct and pretreat the images collected in step S3:

[0096] The intrinsic parameters and distortion coefficients of the camera 1-16 obtained by the camera calibration in step S2 are used to correct the images;

[0097] The collected images are pretreated, including noise removal, image alignment and image matching, so as to ensure the accuracy and consistency of the photo data;

[0098] S4, three-dimensional reconstruction of the topography of the flexible film 1-2 is performed to obtain three-dimensional point cloud:

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

[0100] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An inflatable flexible tactile device for measuring the surface topography of an object, characterized in that, It comprises: The inflatable flexible visual tactile sensor (1) for collecting the topographic image of the surface of the measured object, the clamp (2) for fixing the measured object and the support (3) for adjusting the height of the measured object, which presses the measured object on the surface of the inflatable flexible visual tactile sensor (1) for topographic measurement, the inflatable flexible visual tactile sensor (1) and the support (3) are fixed on the base (4); the clamp (2) is connected to the support (3) through the connecting shaft (5); wherein: The inflatable flexible visual tactile sensor (1) comprises a tactile perception unit and a visual imaging unit, wherein: The tactile perception unit is provided with a reflective layer (1-1), a flexible film (1-2), a fixed ring (1-3), a one-way valve (1-4), a circular acrylic plate (1-5), a light shielding ring (1-6), an annular acrylic plate (1-7) and a light shielding cylindrical barrel (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 barrel (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 through the threads between the light shielding cylindrical barrel (1-8) and the camera light shielding barrel (1-13), and the components of the tactile perception unit and the visual imaging unit are coaxially arranged with the camera optical axis; When the surface of the measured object contacts the inflatable flexible visual tactile sensor (1), the flexible film (1-2) and the external reflective layer (1-1) are deformed, and are tightly attached to the surface of the measured object under the action of the internal air pressure of the inflatable flexible visual tactile sensor (1), so that the accurate object surface concave-convex feature information is collected, and then the three-dimensional reconstruction of the deformed flexible film (1-2) is performed by using photometric stereo technology, so that the reconstruction of the entire topography of the surface of the measured object and the real-time measurement of the size are realized.

2. The inflatable flexible tactile device of claim 1, wherein, The tactile perception unit is sealed by epoxy resin, wherein: The epoxy resin fixes the annular acrylic plate (1-7) at the bottom of the light shielding cylindrical barrel (1-8) to ensure that the bottom is sealed and stable; the epoxy resin fills the gaps between the fixed 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 barrel (1-8); the epoxy resin fills the gap between the one-way valve (1-4) and the fixed ring (1-3), and a sealing film is used for secondary sealing at the interface to ensure the sealing performance of the tactile perception unit after inflation.

3. The inflatable flexible tactile device of claim 1, wherein, In the tactile perception unit: The one-way valve (1-4) is connected with the fixed ring (1-3) for inflating and pressurizing the tactile perception unit, and the tactile perception unit is in a completely sealed state after inflation is completed; The reflective layer (1-1), the flexible film (1-2) and the fixed ring (1-3) constitute a topographic feedback module, and the fixed ring (1-3) is fixedly connected with the lower edges of the reflective layer (1-1) and the flexible film (1-2); wherein: The reflective layer (1-1) is made by mixing titanium dioxide powder and silica gel in a certain proportion, and then uniformly spraying on the flexible film (1-2) after connecting the air pump with the spray pen; it is used to receive light from the light source and reflect, at the same time, improve the light tightness of the flexible film, avoid the potential interference of ambient light on the tactile sensing unit; The flexible film (1-2) is made of silica gel mixed particles with an aluminum powder diameter of 50μm, which is used to contact the measured object and external pressure.

4. The inflatable flexible tactile device of claim 1, wherein, In the visual imaging unit: A plurality of LED lamp beads (1-10) are arranged on the upper surface of the LED ring (1-11) to provide light sources from different directions; The transparent resin lamp cap (1-9) covers the LED lamp beads (1-10) to make the light of the LED lamp beads (1-10) more uniform; The lamp ring base (1-12) is used to fix the LED 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 fish-eye lens (1-15), the camera (1-16) and the LED ring (1-11); The fish-eye lens (1-15) provides a 160° viewing angle to ensure that the camera (1-16) has sufficient visual range for the deformation of the flexible film; The camera (1-16) is arranged at the center of the fixed bottom plate (1-17), and the optical axis of the camera (1-16) remains vertical; The fixed bottom 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 tactile device for measuring surface topography of an object according to claim 4, wherein, The four LED lamp beads (1-10) are arranged on the upper surface of the LED ring (9) respectively, and the colors of the four LED lamp beads (1-10) are arranged in the order of red, green, blue and yellow; the included angle between every two LED lamp beads (1-10) is 90°, and the included angle between each LED lamp bead (1-10) and the optical axis of the camera (1-16) is 90°.

6. The inflatable flexible tactile device of claim 1, wherein, The fixed ring (1-3), the light shielding cylindrical barrel (1-8), the camera light shielding barrel (1-13), the fixed top cover (1-14) and the fixed bottom plate (1-17) constitute the shell of the inflatable flexible visual tactile sensor (1).

7. The inflatable flexible tactile device of claim 1, wherein, The clamp (2) comprises a fastening knob (2-1), a bolt connecting ring (2-2), a secondary clamp (2-3), a solid pin (2-4), a primary clamp (2-5) and an anti-skid pad (2-6), wherein: When fixing the measured object, the fastening knob (2-1) is rotated, the threads of the bolt connecting ring (2-2) enter the fastening knob (2-1), thereby tightening the secondary clamp (2-3) inward, the distance between the secondary clamp (2-3) and the primary clamp (2-5) is reduced, thereby clamping the measured object.

8. The inflatable flexible tactile device of claim 1, wherein, The support (3) comprises a straight rack (3-1), a gear box (3-2), a ratchet wheel (3-3), a shaft pin (3-4), a pawl (3-5), a straight gear (3-6) and a lifting knob (3-7), wherein: After the measured object is clamped, the surface of the measured object is pressed towards the topography feedback module. When pressing down, rotate the lifting knob (3-7) to the appropriate height. The ratchet (3-3) and the pawl (3-5) have self-locking function to prevent the clamp (2) from sliding down. After the measurement is completed, the pawl (3-5) is pushed down to release the self-locking of the ratchet (3-3). Rotate the lifting knob (3-7) to lift the measured object and then push the pawl (3-5) back to prevent the measured object from sliding down.

9. An object surface topography based detection method implemented by the inflatable flexible tactile device of any one of claims 1-8, wherein, It comprises: S1. Before measuring the surface topography of the measured object, calibrate the camera (1-16): Collect complete calibration plate photos under different poses, 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 topography of the object, perform image acquisition: When measuring the surface topography of the measured object, light up the four LED beads (1-10) in different directions respectively. Take a photo for each LED bead (1-10) to collect images of the flexible film (1-2) under different light positions; S3. Correct and preprocess the images collected in step S3: Correct the images using the intrinsic parameters and distortion coefficients of the camera (1-16) obtained 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 topography of the flexible film (1-2) to obtain three-dimensional point cloud: According to the images after preprocessing in step S3, complete the three-dimensional reconstruction of the topography of the flexible film (1-2) by photometric stereo technology to obtain three-dimensional point cloud.

Images