CN115855341A - Optical deep-sea touch sensor and installation method and sensing detection method thereof - Google Patents

Abstract

The invention discloses an optical deep sea touch sensor, an installation method and a sensing detection method thereof, which solve the defects of complex structure, poor pressure resistance and difficult good contact sensing of the existing deep sea touch sensor and have the technical scheme key points that the optical deep sea touch sensor comprises a touch sensing module, an O-shaped ring and an element storage cabin; the touch sensing module comprises a semi-ellipsoidal shell type flexible thin film, a limiting ring and a glass window in sealing connection; liquid is filled between the semi-ellipsoidal shell type flexible film and the glass window; the element storage cabin comprises a pressure-resistant shell fixedly connected through a limiting ring, a detection element arranged in the pressure-resistant shell and a support piece arranged at a port of the pressure-resistant shell; the optical deep sea touch sensor, the installation method and the sensing detection method thereof have good sealing characteristics, can adapt to the contact deformation capability under deep sea high pressure, and realize the touch sensing under deep sea high pressure.

Description

An optical deep-sea tactile sensor and its installation method and sensing detection method

technical field

The invention relates to deep-sea detection and sensing technology, in particular to an optical deep-sea tactile sensor, an installation method and a sensing and detection method thereof.

Background technique

Deep-sea robots are of great significance to ocean engineering, but deep-sea robot operations are still challenging. Since advanced sonar technology cannot be used in the near field, the mainstream control feedback of underwater robots is visual feedback. Therefore, in the low-visibility and highly unstructured deep-sea environment, the fine manipulation ability of the robot is greatly limited.

Endowing deep-sea robots with tactile perception can help improve the precision and compliance of robot operations. Generally speaking, tactile sensors can provide information about the shape of objects and the distribution of contact force. Through the control system based on perception-execution cycle, the robot can respond to the tactile information and adjust the contact force in time to achieve the best operation.

Due to the complexity of the deep-sea environment, many tactile sensors used in terrestrial environments are difficult to apply in the deep-sea environment. At present, underwater tactile sensors are far inferior to tactile sensors used in terrestrial environments in terms of accuracy and resolution. Even so, most underwater tactile sensors can only be used in shallow seas close to the shore, and the sensors face the risk of short circuit underwater, and the deep-sea high pressure also puts forward higher requirements on the structural strength of the sensor.

Contents of the invention

The purpose of the present invention is to provide an optical deep-sea tactile sensor and its installation method and sensing detection method, which have good sealing characteristics, can adapt to the contact deformation ability under high pressure in deep sea, and realize tactile perception under high pressure in deep sea.

Above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

An optical deep-sea tactile sensor, including a tactile sensing module, an O-ring, and a component storage compartment;

The tactile sensing module includes a semi-ellipsoid shell-shaped flexible film, a limit ring sleeved on the semi-ellipsoid shell-shaped flexible film, and a glass window sealed and connected to the semi-ellipsoid shell-shaped flexible film; the semi-ellipsoid shell A liquid that offsets the external hydrostatic pressure is filled between the type flexible film and the glass window;

The component storage compartment includes a pressure-resistant shell fixedly connected to the tactile sensing module through a limiting ring, a detection element installed in the pressure-resistant shell, and a support member installed on the port of the pressure-resistant shell to support the glass window;

The port of the pressure-resistant shell is provided with a groove on the outer periphery of the support member for the O-ring to fit and seal.

Preferably, the semi-ellipsoid shell-shaped flexible film includes a semi-ellipsoid film integrally connected with a mounting ring, and the inner wall of the mounting ring is provided with a hemispherical protrusion for sealing contact with the glass window.

As a preference, the edge of the installation ring has a boss extending outward in the circumferential direction, and a plurality of limiting holes are opened on the boss;

The end of the limit ring is protruded with a limit block inserted into the limit hole;

The outer periphery of the port of the pressure-resistant housing is provided with a slot for assembly of the limit block, and the slot communicates with the limit block to provide a threaded hole for screw penetration for fixed installation.

Preferably, the detection element includes a camera, and the surface of the support member is provided with a through hole for the camera to pass through for detection.

Preferably, an underwater connector connected to the detection element in the cabin is installed on the rear side of the pressure-resistant housing.

A sensing detection method based on an optical deep-sea tactile sensor is characterized in that it includes the following steps:

The tactile sensor is assembled on the deep-sea robot, and the external contact information is sensed by simulating the finger pad through the semi-ellipsoidal flexible film. When an external force is applied to the semi-ellipsoidal flexible film, contact deformation occurs;

The camera obtains the three-dimensional information in the semi-ellipsoidal flexible film through the glass window;

Signals are transmitted through underwater connectors for signal analysis and processing to complete tactile sensing detection.

Preferably, the three-dimensional information obtained in the semi-ellipsoidal flexible film is specifically:

The spatial three-dimensional information of the tactile deformation field is reconstructed by the photometric stereo method, and the hardware part adopts an ordinary camera (32) and RGB light sources (35) of different colors, or

The spatial three-dimensional information of the tactile deformation field is reconstructed by a stereo vision method, including any one of the binocular stereo vision method, the structured light method, and the TOF method. Correspondingly, the built-in cameras (32) of the sensor correspond to binocular cameras, structural cameras, TOF camera.

An installation method applied to a deep-sea tactile sensor is characterized in that it includes the following steps:

Through the limit ring of the tactile sensing module, the semi-ellipsoidal flexible film is limited and installed;

Submerge the semi-ellipsoidal flexible film port facing upwards vertically in a container filled with liquid after limit installation;

Push the glass window vertically into the port of the semi-ellipsoidal flexible film to complete the sealing and fixing of the glass window on the semi-ellipsoidal flexible film;

Place the detection element in the pressure-resistant shell of the element storage compartment, and install a support at the port of the pressure-resistant shell;

Place the O-ring in the groove of the pressure-resistant housing;

Vacuumize the component storage compartment through vacuum equipment, and at the same time install the assembled tactile sensing module on one side of the support, and assemble and fix it after being absorbed by the internal and external pressure difference;

The underwater connector is sealed, and the internal air pressure of the component storage compartment is restored by disassembling the underwater connector to disassemble the components.

In summary, the present invention has the following beneficial effects:

Through the semi-ellipsoidal flexible film of the tactile sensing module, the limit ring and the glass window, filling the liquid between the semi-ellipsoidal flexible film and the glass window can realize the hydraulic compensation balance, so that the tactile sensing module is no longer harmful to the environment. The pressure is sensitive, and it can have good contact deformation ability in the deep sea environment, realizing the tactile perception in the deep sea environment; the limit and fixed connection of the tactile sensing module, O-ring and component storage compartment can realize the good sealing of the sensor as a whole, The overall installation is recommended and the structure is simple, and it has great application potential in underwater and deep sea.

Description of drawings

1 is a schematic diagram of the overall structure of an optical deep-sea tactile sensor;

Figure 2 is a schematic diagram of the exploded structure of each component of the tactile sensing module;

Fig. 3 is a schematic diagram of the explosive structure of the semi-ellipsoidal shell type flexible membrane and the limit ring;

Fig. 4 is the sectional view of the assembly of the tactile sensing module;

Fig. 5 is the schematic diagram of the tactile perception module;

Fig. 6 is a structural schematic diagram of a component storage compartment;

Figure 7 is a schematic diagram of camera observation of the sensor.

In the figure: 1. Tactile sensing module; 11. Glass window; 12. Semi-ellipsoid shell-shaped flexible film; 121. Limiting hole; 122. Semicircular protrusion; 13. Limiting ring; 131. Limiting block; 132. Threaded hole of limit ring; 2. O-ring; 3. Component storage compartment; 31. Underwater connector; 32. Camera; 33. Pressure-resistant shell; 331. Threaded hole of pressure-resistant shell; 332. Card slot; 333, groove; 34, support piece; 35, light source.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

According to one or more embodiments, an optical deep-sea tactile sensor is disclosed. As shown in FIG. 1 , it includes a tactile sensing module 1 , an O-ring 2 , and a component storage compartment 3 .

As shown in FIG. 2 , the tactile sensing module 1 includes a semi-ellipsoid shell-shaped flexible film 12 , a limiting ring 13 , and a glass window 11 , and all components can be assembled to form a semi-ellipsoid elastic body. As shown in Figure 3 and Figure 4, the limit ring 13 is sleeved on the semi-ellipsoid shell-shaped flexible film 12, and the glass window 11 is sealed and connected to the inner side of the semi-ellipsoid shell-shaped flexible film 12, and the glass window 11 and the semi-ellipsoid shell-shaped A closed space is formed between the flexible films 12, which are filled with liquid, which can offset the external hydrostatic pressure. When the tactile sensor is installed on the deep-sea robot for deep-sea detection, the semi-ellipsoid shell-shaped flexible film 12 simulates the fingertips to sense the external contact information. , when an external force is applied to the semi-ellipsoid shell-shaped flexible film 12, contact deformation occurs. On this basis, the tactile sensing can be realized by converting the contact deformation information into an electrical or optical signal that can be understood by a computer. By filling the inner area of the flexible membrane with liquid to achieve hydraulic compensation balance, the water-membrane composite elastomer is no longer sensitive to the environmental pressure, so that the water-membrane composite elastomer has almost the same contact deformation ability in the whole sea depth. The tactile sensing module 1 utilizes liquid fluidity to generate contact deformation, which realizes pressure compensation so that the sensor can directly measure relative pressure, and utilizes its incompressibility to ensure that the tactile sensing module 1 still has contact deformation capability under high pressure. Most tactile sensors used in terrestrial environments are difficult to measure relative pressure underwater, and existing underwater tactile sensors are difficult to guarantee the contact deformation ability of elastomers under high pressure.

The semi-ellipsoid shell-shaped flexible membrane 12 includes a semi-ellipsoid membrane and a mounting ring integrally connected. The inner wall of the mounting ring is provided with a hemispherical protrusion 122 in the circumferential ring, and the outer periphery of the glass window 11 is sealed against the hemispherical protrusion 122 to realize the sealing between the glass window 11 and the semi-ellipsoid shell-shaped flexible film 12 . The edge of the mounting ring has a boss extending outward in the circumferential direction, and a plurality of limiting holes 121 are opened on the boss. The end of the limit ring 13 is protruded with a limit block 131 that is inserted into the limit hole 121. The position hole 121 is set to limit the position of the semi-ellipsoidal flexible film 12 .

The sensing principle of the tactile sensing module 1 in the deep sea environment is shown in Figure 5. For the convenience of expression, the tactile sensing module 1 is simplified as a hemispherical film with a sealed bottom and filled with liquid, as shown in Figure 5(1). Under the action of hydrostatic pressure _PH , the internal liquid pressure and the ambient pressure cancel. Therefore, if the thickness variation of the flexible film is not considered, it can be considered that the sensing module can always be in the same shape at different depths. When an object is pressed against the surface of the flexible film, the film deforms to take on the surface shape of the object, as shown in Figure 5(2). Since the deformation of the flexible film only depends on the shape of the pressed object, the tactile sensing module 1 has almost the same contact deformation ability at all depths of the sea, which is a characteristic that the tactile sensor used in the normal pressure environment does not have.

As shown in Figure 6, the component storage compartment 3 includes a pressure-resistant casing 33 and a support member 34 supported on the glass window 11. The detection element is installed in the pressure-resistant casing 33 of the component storage compartment 3, and the support component 34 is fixedly installed on the pressure-resistant The port of the casing 33 is supported and installed between the pressure-resistant casing 33 and the glass window 11. The support member 34 is preferably made of a metal material, so that the maximum principal stress of the glass window 11 under deep-sea pressure is greatly reduced, and the durability of the device is greatly improved. pressure capacity. The port of the pressure-resistant housing 33 is provided with a groove 333 on the outer periphery of the support member 34 for the sealing of the O-ring 2, and the O-ring 2 is used to provide sealing support between the component storage compartment 3 and the tactile sensing module 1 to avoid Risk of short circuit due to liquid leakage.

On the port peripheral side wall of the pressure-resistant shell 33, a plurality of card slots 332 are arranged at intervals, and the card slots 332 are matched with the limit blocks 131 on the limit ring 13. Through the combination of the card slots 332 and the limit blocks 131, the Circumferential limit, threaded holes are provided in communication between the card slot 332 and the limit block 131, which are respectively the limit ring threaded hole 132 provided on the limit ring 13 and the card slot 332 provided on the pressure-resistant shell 33 The threaded hole 331 of the pressure-resistant shell of the screw is passed through to achieve axial fixation, thereby realizing the fixed connection between the tactile sensing module 1 and the component storage compartment 3 .

The detection element includes a camera 32 , and a through hole connected to the pressure-resistant housing 33 is opened on the surface of the support 34 , and the camera 32 is installed through the through hole to capture and collect images on one side of the tactile sensing module 1 .

An underwater connector 31 is also connected to the rear side of the pressure-resistant casing 33, through which the underwater connector 31 is connected to the detection element in the element storage compartment 3 for signal transmission. The outer wall of the underwater connector 31 is in sealing connection with the pressure-resistant shell 33 . The underwater connector 31 on the pressure-resistant housing 33 can be used as a sealing plug for the pressure-resistant housing. Through the disassembly of the underwater connector 31, the vacuuming between the component storage compartment 3 and the tactile sensing module 1 can be completed to store the components. The cabin 3 is in a state of high negative pressure to facilitate installation and disassembly. Through the vacuum installation, the glass window 11 no longer needs to be fixed on the component storage compartment 3 through bolts and other connecting parts, which greatly improves the compactness of the structure. In the deep sea, the huge internal and external pressure difference can provide sufficient pre-tightening force, so that the O-ring 2 can produce sufficient extrusion seal to prevent seawater from entering the interior of the component storage compartment 3 .

As shown in FIG. 6 , the transformation method of tactile deformation information based on photometric stereo vision can be used, and the hardware part consists of a single ordinary camera 32 and three groups of RGB light sources 35 of different colors. Under the illumination of the RGB light source 35, the camera can observe the rich color and shadow information on the inner surface of the semi-ellipsoidal flexible film 12, and use the reflection image on the inner surface to reconstruct the spatial three-dimensional information of the tactile deformation field. Specifically, the spatial position of the inner surface of the semi-ellipsoidal flexible film 12 is the unknown quantity to be obtained. Because it involves three dimensions of x, y, and z, the unknown quantity to be obtained is also three groups. Based on a certain physical model, such as Lambert reflection model, directional light source 35 model, etc., the functional relationship between the reflected light intensity R on the inner surface of the flexible film and the spatial position (x, y, z) on the inner surface of the film can be established, that is, R=f (x, y, z), where the reflected light intensity R can be obtained directly through camera shooting. Since the lighting source 35 has three colors of RGB, three sets of equations are established according to the reflection conditions of different colors. The number of unknowns is (x, y, z) is equal to the number of equations, so it can be solved to obtain the three-dimensional information of the film.

Stereoscopic reconstruction can also be performed based on the stereoscopic vision method, and one of the binocular stereoscopic vision method, the structured light method, and the TOF method can be used, or other stereoscopic reconstruction methods can be used. The binocular stereo vision method is adopted, and the built-in camera 32 is a binocular camera; the structured light rule is used to build a structural camera, and the TOF rule is used to build a TOF camera to capture the image changes on one side of the tactile perception module 1 due to contact deformation. reconstruction.

For clarity, here is an example:

As shown in Figure 7, the built-in camera used can be a 130° wide-angle fisheye lens, the distance between the lens and the glass window 11 is 5 mm, and the thickness of the glass window 11 itself is 20 mm. Considering the refraction of light inside the sensor, the refractive index of the glass window 11 is n ₁ =1.5, the refractive index of water is n ₂ =1.33, and the refractive index of air is n ₃ =1. Under the effect of refraction, the viewing angle of the camera 32 is reduced from 130° to 86°, as shown in the area surrounded by the dotted line in FIG. 7 . Considering that only the central area of the sensor produces a deformation field in most tasks, although the angle of view of the camera 32 is reduced due to refraction, this field of view area can already cover most working conditions. The finite element results show that the maximum principal stress of the sensor glass window 11 drops from 52.1MPa to 6.89MPa under a pressure of 10MPa, which is 87%. This design enables the sensor to withstand environmental pressure even at a depth of 10,000 meters.

According to one or more embodiments, a sensing detection method of an optical deep-sea tactile sensor is disclosed, including the following steps:

The tactile sensor is assembled on the deep-sea robot, and the semi-ellipsoid shell-shaped flexible film 12 is used to simulate the external contact information of the finger pad, and when an external force is applied to the semi-ellipsoid shell-shaped flexible film 12, contact deformation occurs;

The camera 32 obtains the three-dimensional information in the semi-ellipsoidal flexible film 12 through the glass window 11;

Signals are transmitted through the underwater connector 31 for signal analysis and processing to complete tactile sensing detection.

Specifically, the acquisition of the three-dimensional information in the semi-ellipsoidal flexible film 12 can be:

Three groups of RGB light sources 35 of different colors are installed on the support member 34 through the detection element to irradiate the semi-ellipsoidal shell-shaped flexible film 12;

The camera 32 collects and obtains the color and shadow information of the inner surface of the semi-ellipsoidal flexible film 12;

Reconstruction of spatial three-dimensional information of tactile deformation field from internal surface reflection images.

Specifically, the acquisition of the three-dimensional information in the semi-ellipsoidal flexible film 12 can also be: the built-in camera 32 is a binocular camera using the binocular stereo vision method or a structured light camera using the structured light method or a TOF camera using the TOF method, based on Stereo vision method for stereo reconstruction.

According to one or more embodiments, a method for installing an optical deep-sea tactile sensor is disclosed, including the following steps:

Through the limit ring 13 of the tactile sensing module 1, limit installation on the semi-ellipsoidal flexible film 12;

Submerge the semi-ellipsoidal flexible membrane 12 with the port facing upwards vertically in a container filled with filling liquid;

Push the glass window 11 into the port of the semi-ellipsoid shell-shaped flexible film 12 in the vertical direction to complete the sealing and fixing of the glass window 11 on the semi-ellipsoid shell-shaped flexible film 12;

Place the detection element in the pressure-resistant shell 33 of the element storage compartment 3, and install a support 34 at the port of the pressure-resistant shell 33;

Place the O-ring 2 in the groove 333 of the pressure-resistant housing 33;

Vacuumize the component storage compartment 3 by vacuuming equipment, and install the assembled tactile sensing module 1 on one side of the support member 34, and then assemble and fix it after adsorption by the internal and external pressure difference;

The underwater connector 31 is sealed, and the internal air pressure of the component storage compartment 3 is restored by disassembling the underwater connector 31 to disassemble the components.

Through the above-mentioned installation method, it is possible to avoid the generation of air bubbles when the film is filled with liquid and to ensure the tightness of the internal liquid under the design requirements of a compact structure.

This specific embodiment is only an explanation of the present invention, and it is not a limitation of the present invention. Those skilled in the art can make modifications to this embodiment without creative contribution as required after reading this specification, but as long as they are within the rights of the present invention All claims are protected by patent law.

Claims (8)

1. An optical deep-sea tactile sensor is characterized in that: it includes a tactile perception module (1), an O-ring (2), and an element storage compartment (3); The tactile sensing module (1) includes a semi-ellipsoidal flexible film (12), a limiting ring (13) sleeved on the semi-ellipsoidal flexible film (12), and a sealing connection to the semi-ellipsoidal film. The glass window (11) of the flexible film (12); the liquid that offsets the external hydrostatic pressure is filled between the semi-ellipsoidal shell-shaped flexible film (12) and the glass window (11); The component storage compartment (3) includes a pressure-resistant casing (33) fixedly connected to the tactile sensing module (1) through a limit ring (13), a detection element installed in the pressure-resistant casing (33), and a detection element installed in the The port of the pressure-resistant housing (33) is supported on the support (34) of the glass window (11); The port of the pressure-resistant shell (33) is provided with a groove (333) on the outer periphery of the support member (34) for the O-ring (2) to fit and seal. 2. The optical deep-sea tactile sensor according to claim 1, characterized in that: the semi-ellipsoid shell-type flexible film (12) includes a semi-ellipsoid film and a mounting ring integrally connected, and the inner side of the mounting ring The wall circumferential ring is provided with hemispherical protrusions (122) for sealing abutment of the glass window (11). 3. The optical deep-sea tactile sensor according to claim 2, characterized in that: the edge of the installation ring has a boss extending outward in the circumferential direction, and a plurality of limit holes (121) are provided on the boss; The end of the limit ring (13) is protruded with a limit block (131) pierced and snapped into the limit hole (121); The outer periphery of the port of the pressure-resistant shell (33) is provided with a card slot (332) for the assembly of the limit block (131), and the card slot (332) communicates with the limit block (131) and is provided with a hole for screw penetration. Threaded holes for fixed mounting. 4. The optical deep-sea tactile sensor according to claim 1, characterized in that: the detection element includes a camera (32), and the surface of the support (34) is provided with a hole for the camera (32) to penetrate and detect. through hole. 5. The optical deep-sea tactile sensor according to claim 1, characterized in that: an underwater connector (31) connected to the detection element in the cabin is installed on the rear side of the pressure-resistant casing (33). 6. A sensing detection method based on the optical deep-sea tactile sensor claimed in claim 1, characterized in that, comprising the following steps: Assembling the tactile sensor on the deep-sea robot, simulating the finger pad to sense external contact information through the semi-ellipsoid shell-shaped flexible film (12), and generating contact deformation when an external force is applied to the semi-ellipsoid shell-shaped flexible film (12); The camera (32) obtains the three-dimensional information in the semi-ellipsoidal flexible film (12) through the glass window (11); Signals are transmitted through the underwater connector (31) for signal analysis and processing to complete tactile sensing detection. 7. The sensing detection method according to claim 6, characterized in that, obtaining the three-dimensional information in the semi-ellipsoid shell type flexible film (12) is specifically: The spatial three-dimensional information of the tactile deformation field is reconstructed by the photometric stereo method, and the hardware part adopts an ordinary camera (32) and RGB light sources (35) of different colors, or The spatial three-dimensional information of the tactile deformation field is reconstructed by a stereo vision method, including any one of the binocular stereo vision method, the structured light method, and the TOF method. Correspondingly, the built-in cameras (32) of the sensor correspond to binocular cameras, structural cameras, TOF camera. 8. An installation method applied to the deep-sea tactile sensor according to claim 1, characterized in that, comprising the following steps: Limit installation on the semi-ellipsoid shell-shaped flexible film (12) through the limit ring (13) of the tactile sensing module (1); Submerge the semi-ellipsoidal flexible membrane (12) with the port facing upwards vertically in a container filled with liquid; Push the glass window (11) into the port of the semi-ellipsoid shell-shaped flexible film (12) in the vertical direction to complete the sealing and fixing of the glass window (11) on the semi-ellipsoid shell-shaped flexible film (12); The detection element is placed in the pressure-resistant shell (33) of the element storage compartment (3), and a support (34) is installed at the port of the pressure-resistant shell (33); Place the O-ring (2) in the groove (333) of the pressure-resistant casing (33); Vacuumize the component storage compartment (3) by vacuuming equipment, and install the assembled tactile sensing module (1) on one side of the support (34), and then assemble and fix it after being adsorbed by the internal and external pressure difference; The underwater connector (31) is sealed, and the internal air pressure of the component storage compartment (3) is restored by disassembling the underwater connector (31), and the parts are disassembled.

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