Optical deep-sea tactile sensor and installation method and sensing detection method thereof

Abstract

The application discloses an optical deep-sea tactile sensor and an installation method and a sensing detection method thereof, and solves the problems of complex structure, poor pressure resistance and poor contact sensing of the existing deep-sea tactile sensor, and the technical scheme is as follows: the tactile sensor comprises a tactile sensing module, an O-shaped ring and an element storage cabin; the tactile sensing module comprises a semi-elliptical shell type flexible film, a limiting ring and a sealingly connected glass window; the semi-elliptical shell type flexible film and the glass window are filled with liquid; the element storage cabin comprises a pressure-resistant shell fixedly connected through the limiting ring, a detection element installed in the pressure-resistant shell and a support installed at a port of the pressure-resistant shell; a sealing groove is arranged on the outer periphery of the support at the port of the pressure-resistant shell, the optical deep-sea tactile sensor and the installation method and the sensing detection method thereof have good sealing characteristics, can adapt to the contact deformation ability under high pressure in the deep sea, and realize the tactile sensing under high pressure in the deep sea.

Description

Technical Field

[0001] This invention relates to deep-sea detection and sensing technology, and in particular to an optical deep-sea tactile sensor and its installation and sensing methods. Background Technology

[0002] Deep-sea robots are of great significance to marine engineering; however, operating them remains challenging. Because advanced sonar technology cannot be used in the near field, the mainstream control feedback for underwater robots is currently visual feedback. Therefore, in the low-visibility, highly unstructured deep-sea environment, the robot's ability to perform precise maneuvers is significantly limited.

[0003] Imparting tactile perception to deep-sea robots helps improve the accuracy and responsiveness of their operations. Generally, tactile sensors can provide information about the shape of objects and the distribution of contact forces. Through a control system based on a sense-execution loop, the robot can react to tactile information and adjust the contact forces in a timely manner to achieve optimal operation.

[0004] Due to the complexity of the deep-sea environment, many tactile sensors used in terrestrial environments are difficult to apply in the deep sea. Currently, underwater tactile sensors are far inferior to those used in terrestrial environments in terms of accuracy and resolution. Even so, most underwater tactile sensors can only be used in shallow waters relatively close to the shore, and the sensors face the risk of short circuits underwater. The high pressure in the deep sea also places higher demands on the structural strength of the sensors. Summary of the Invention

[0005] The purpose of this invention is to provide an optical deep-sea tactile sensor and its installation and sensing methods, which has good sealing characteristics, can adapt to contact deformation under deep-sea high pressure, and realize tactile perception under deep-sea high pressure.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0007] An optical deep-sea tactile sensor includes a tactile sensing module, an O-ring, and a component storage compartment;

[0008] The tactile sensing module includes a semi-ellipsoidal shell-shaped flexible film, a limiting ring sleeved on the semi-ellipsoidal shell-shaped flexible film, and a glass window sealed and connected to the semi-ellipsoidal shell-shaped flexible film; the space between the semi-ellipsoidal shell-shaped flexible film and the glass window is filled with a liquid to counteract external hydrostatic pressure.

[0009] The component storage compartment includes a pressure-resistant housing fixedly connected to the tactile sensing module by a limiting ring, a detection element installed inside the pressure-resistant housing, and a support member installed at the port of the pressure-resistant housing to support the glass window.

[0010] The port of the pressure-resistant housing is provided with a groove on the outer periphery of the support member for the O-ring to be inserted and sealed.

[0011] Preferably, the semi-ellipsoidal shell type flexible film includes an integrally connected semi-ellipsoidal film and a mounting ring, and the inner sidewall of the mounting ring is provided with a hemispherical protrusion for sealing and abutting the glass window.

[0012] Preferably, the edge of the mounting ring extends outward in a circumferential direction with a boss, and the boss is provided with a plurality of limiting holes.

[0013] The end of the limiting ring has a protruding limiting block that is inserted into the limiting hole;

[0014] The outer periphery of the port of the pressure-resistant housing is provided with a slot for assembling the limiting block, and the slot is connected to the limiting block and has a threaded hole for screws to pass through for fixed installation.

[0015] Preferably, the detection element includes a camera, and the surface of the support member has a through hole for the camera to pass through for detection.

[0016] Preferably, an underwater connector for connecting to the detection elements inside the cabin is installed on the rear side of the pressure-resistant housing.

[0017] A sensing and detection method based on an optical deep-sea tactile sensor, characterized by comprising the following steps:

[0018] A tactile sensor is mounted on a deep-sea robot. The sensor simulates the fingertip to sense external contact information through a semi-ellipsoidal shell-shaped flexible film. When an external force is applied to the semi-ellipsoidal shell-shaped flexible film, contact deformation occurs.

[0019] The camera acquires three-dimensional information within a semi-ellipsoidal shell-shaped flexible film through a glass window;

[0020] Signals are transmitted via an underwater connector for signal analysis and processing to complete tactile sensing detection.

[0021] As a preferred method, obtaining the three-dimensional information within the semi-ellipsoidal shell-shaped flexible film specifically involves:

[0022] The spatial three-dimensional information of the tactile deformation field is reconstructed using photometric stereo method. The hardware part uses a common camera (32) and RGB light sources of different colors (35), or

[0023] The spatial three-dimensional information of the tactile deformation field is reconstructed by stereo vision methods, including any one of binocular stereo vision, structured light, and TOF methods. Correspondingly, the built-in camera (32) of the sensor is a binocular camera, a structured camera, and a TOF camera, respectively.

[0024] A method for installing a deep-sea tactile sensor, characterized by comprising the following steps:

[0025] The tactile sensing module uses a limiting ring to limit the installation on the semi-ellipsoidal shell-shaped flexible film.

[0026] After the limit installation is completed, the semi-ellipsoidal shell-shaped flexible film is vertically immersed in a container filled with liquid with the port facing upwards.

[0027] The glass window is pushed vertically into the port of the semi-ellipsoidal shell flexible film to complete the sealing and fixation of the glass window on the semi-ellipsoidal shell flexible film.

[0028] The detection element is placed in the pressure-resistant housing of the element storage compartment, and a support is installed at the port of the pressure-resistant housing;

[0029] Place the O-ring into the groove of the pressure-resistant housing;

[0030] The component storage chamber is evacuated using a vacuum pump, and the assembled tactile sensing module is installed on one side of the support. It is then assembled and fixed by adsorption through the internal and external pressure difference.

[0031] The underwater connector is sealed, and the internal air pressure of the component storage tank is restored by disassembling the underwater connector, allowing for component disassembly.

[0032] In summary, the present invention has the following beneficial effects:

[0033] The tactile sensing module utilizes a semi-ellipsoidal flexible film, a limiting ring, and a glass window. By filling the space between the semi-ellipsoidal flexible film and the glass window with liquid, hydraulic compensation and balance can be achieved. This makes the tactile sensing module no longer sensitive to environmental pressure, enabling it to have good contact deformation capabilities in deep-sea environments and achieve tactile sensing in these environments. The limiting and fixing connections of the tactile sensing module, O-ring, and component storage compartment ensure good sealing of the entire sensor. The overall installation is simple and easy to follow, making it highly promising for underwater and deep-sea applications. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the overall structure of an optical deep-sea tactile sensor.

[0035] Figure 2 This is an exploded structural diagram of the various components of the tactile sensing module;

[0036] Figure 3 This is a schematic diagram of the exploded structure of a semi-ellipsoidal shell-shaped flexible film and a limiting ring.

[0037] Figure 4 A cross-sectional view of the tactile sensing module assembly;

[0038] Figure 5 This is a schematic diagram of the tactile sensing module;

[0039] Figure 6 This is a schematic diagram of the component storage compartment.

[0040] Figure 7 This is a schematic diagram of the sensor's camera observation.

[0041] In the diagram: 1. Tactile sensing module; 11. Glass window; 12. Semi-ellipsoidal shell-shaped flexible film; 121. Limiting hole; 122. Semi-circular protrusion; 13. Limiting ring; 131. Limiting block; 132. Limiting ring threaded hole; 2. O-ring; 3. Component storage compartment; 31. Underwater connector; 32. Camera; 33. Pressure-resistant shell; 331. Pressure-resistant shell threaded hole; 332. Slot; 333. Groove; 34. Support component; 35. Light source. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the accompanying drawings.

[0043] According to one or more embodiments, an optical deep-sea tactile sensor is disclosed, such as... Figure 1 As shown, it includes a tactile sensing module 1, an O-ring 2, and a component storage compartment 3.

[0044] like Figure 2 As shown, the tactile sensing module 1 includes a semi-ellipsoidal shell-shaped flexible film 12, a limiting ring 13, and a glass window 11. All components, when assembled, can form a semi-ellipsoidal elastomer. For example... Figure 3 and Figure 4As shown, a limiting ring 13 is fitted onto a semi-ellipsoidal shell-shaped flexible membrane 12, and a glass window 11 is sealed to the inside of the semi-ellipsoidal shell-shaped flexible membrane 12. A sealed space is formed between the glass window 11 and the semi-ellipsoidal shell-shaped flexible membrane 12, which is filled with liquid to counteract external hydrostatic pressure. When the tactile sensor is installed on the deep-sea robot for deep-sea detection, it simulates the fingertip to sense external contact information through the semi-ellipsoidal shell-shaped flexible membrane 12. When an external force is applied to the semi-ellipsoidal shell-shaped flexible membrane 12, contact deformation occurs. Based on this, the contact deformation information is converted into an electrical or optical signal that can be understood by a computer to realize tactile sensing. By filling the internal region of the flexible membrane with liquid to achieve hydraulic compensation balance, the water-film composite elastomer is no longer sensitive to environmental pressure, thus enabling the water-film composite elastomer to have almost the same contact deformation capacity throughout the entire ocean depth. The tactile sensing module 1 utilizes the fluidity of the liquid to generate contact deformation, thus achieving pressure compensation so that the sensor can directly measure relative pressure, and also utilizing its incompressibility to ensure that the tactile sensing module 1 still has the ability to deform under high pressure. Most tactile sensors used in terrestrial environments are difficult to measure relative pressure underwater, while existing underwater tactile sensors cannot guarantee the contact deformation capability of the elastomer under high pressure.

[0045] The semi-ellipsoidal shell flexible film 12 includes an integrally connected semi-ellipsoidal film and a mounting ring. The inner sidewall of the mounting ring has a hemispherical protrusion 122, and the outer periphery of the glass window 11 abuts against the hemispherical protrusion 122 to achieve a seal between the glass window 11 and the semi-ellipsoidal shell flexible film 12. The edge of the mounting ring extends outwards with a boss, and several limiting holes 121 are formed on the boss. The end of the limiting ring 13 protrudes with a limiting block 131 that passes through and is fitted into the limiting hole 121. When the limiting ring 13 is fitted onto the semi-ellipsoidal shell flexible film 12, the limiting block 131 passing through the limiting hole 121 limits the semi-ellipsoidal shell flexible film 12.

[0046] The tactile sensing module 1's sensing principle in deep-sea environments is as follows: Figure 5 As shown, for ease of description, the tactile sensing module 1 is simplified as a hemispherical film with a sealed bottom and filled with liquid, such as... Figure 5 As shown in (1). Under hydrostatic pressure P H Under this action, the internal liquid pressure cancels out the ambient pressure. Therefore, if we disregard the thickness variation of the flexible film, we can assume that the sensing module will always maintain the same shape at different depths. When an object is pressed onto the surface of the flexible film, the film deforms, taking on the shape of the object's surface, such as... Figure 5 (2) As shown. Since the deformation of the flexible film depends only on the shape of the object being pressed, the tactile sensing module 1 has almost the same contact deformation capability at all ocean depths, a characteristic that tactile sensors used in normal pressure environments do not possess.

[0047] like Figure 6 As shown, the component storage chamber 3 includes a pressure-resistant outer shell 33 and a support member 34 supported on the glass window 11. Detection elements are installed inside the pressure-resistant outer shell 33 of the component storage chamber 3. The support member 34 is fixedly installed at the port of the pressure-resistant outer shell 33, providing support between the pressure-resistant outer shell 33 and the glass window 11. The support member 34 is preferably made of metal, which significantly reduces the maximum principal stress of the glass window 11 under deep-sea pressure, greatly improving the pressure resistance of the device. The port of the pressure-resistant outer shell 33 has a groove 333 on the outer periphery of the support member 34 for O-rings 2 to be inserted for sealing. The O-rings 2 provide a sealed support between the component storage chamber 3 and the tactile sensing module 1, preventing the risk of short circuits due to liquid leakage.

[0048] Several slots 332 are spaced apart on the outer peripheral sidewall of the port of the pressure-resistant housing 33. The slots 332 correspond to and match the limiting blocks 131 on the limiting ring 13. The combination of the slots 332 and the limiting blocks 131 achieves circumferential limiting. Threaded holes are opened on the slots 332 and the limiting blocks 131, namely the limiting ring threaded hole 132 on the limiting ring 13 and the pressure-resistant housing threaded hole 331 on the slots 332 of the pressure-resistant housing 33. The axial fixing is achieved by the insertion of screws, thereby realizing the fixed connection between the tactile sensing module 1 and the component storage compartment 3.

[0049] The detection element includes a camera 32. A through hole is provided on the surface of the support member 34, which communicates with the pressure-resistant housing 33. The camera 32 is installed through the through hole to capture and collect images of one side of the tactile sensing module 1.

[0050] An underwater connector 31 is connected to the rear side of the pressure-resistant housing 33. This connector connects to the detection element inside the component storage chamber 3 for signal transmission. The outer wall of the underwater connector 31 is sealed to the pressure-resistant housing 33. The underwater connector 31 acts as a sealing plug on the pressure-resistant housing 33. By assembling and disassembling the underwater connector 31, a vacuum can be created between the component storage chamber 3 and the tactile sensing module 1, placing the component storage chamber 3 under high negative pressure for easy installation and disassembly. Vacuum installation eliminates the need for bolts or other fasteners to fix the glass window 11 to the component storage chamber 3, significantly improving structural compactness. In the deep sea, the large internal and external pressure difference provides sufficient preload, ensuring the O-ring 2 provides a sufficient compression seal to prevent seawater from entering the component storage chamber 3.

[0051] like Figure 6As shown, a tactile deformation information conversion method based on photometric stereo vision can be used. The hardware consists of a single ordinary camera 32 and three sets of RGB light sources 35 of different colors. Under the illumination of the RGB light sources 35, the camera can observe rich color and shadow information on the inner surface of the semi-ellipsoidal shell flexible film 12. The spatial three-dimensional information of the tactile deformation field can be reconstructed using the reflected image of the inner surface. Specifically, the spatial position of the inner surface of the semi-ellipsoidal shell flexible film 12 is the unknown quantity to be determined. Since it involves three dimensions (x, y, z), there are also three sets of unknown quantities to be determined. Based on certain physical models, such as the Lamborgh reflection model and the directional light source 35 model, a functional relationship between the reflected light intensity R of the inner surface of the flexible film and the spatial position (x, y, z) of the inner surface of the film can be established, i.e., R = f(x, y, z), where the reflected light intensity R can be directly obtained by the camera. Since the illumination source 35 has three colors (RGB), three sets of equations are established according to the reflection of different colors. The number of unknowns (x, y, z) is equal to the number of equations, so the three-dimensional information of the film can be obtained by solving the equations.

[0052] Stereo reconstruction can also be performed based on stereo vision methods, such as binocular stereo vision, structured light, or Time-of-Flight (TOF), or other stereo reconstruction methods. For binocular stereo vision, the built-in camera 32 is a binocular camera; for structured light, a built-in structured camera is used; and for TOF, a built-in TOF camera is used to reconstruct images of changes caused by contact deformation on one side of the tactile sensing module 1.

[0053] To illustrate this clearly, here is an example:

[0054] like Figure 7 As shown, the built-in camera used can be a 130° wide-angle fisheye lens, with a distance of 5mm between the lens and the glass window 11, and the glass window 11 itself has a thickness of 20mm. Considering the refraction of light inside the sensor, the refractive index of the glass window 11 is taken as n1 = 1.5, the refractive index of water as n2 = 1.33, and the refractive index of air as n3 = 1. Under the effect of refraction, the field of view of the camera 32 is reduced from 130° to 86°, as... Figure 7 The area enclosed by the dashed line is shown. Considering that the sensor only generates a deformation field in the central region during most tasks, this field of view is sufficient to cover most operating conditions, even though the field of view of camera 32 is reduced due to refraction. Finite element results show that under a pressure of 10 MPa, the maximum principal stress of the sensor glass window 11 decreases from 52.1 MPa to 6.89 MPa, a reduction of 87%. This design allows the sensor to withstand environmental pressure even at depths of tens of thousands of meters.

[0055] According to one or more embodiments, a sensing and detection method for an optical deep-sea tactile sensor is disclosed, comprising the following steps:

[0056] A tactile sensor is mounted on a deep-sea robot. The semi-ellipsoidal shell-shaped flexible film 12 simulates the fingertip to sense external contact information. When an external force is applied to the semi-ellipsoidal shell-shaped flexible film 12, contact deformation occurs.

[0057] Camera 32 acquires three-dimensional information within the semi-ellipsoidal shell-shaped flexible film 12 through the glass window 11;

[0058] Signals are transmitted through the underwater connector 31 for signal analysis and processing to complete tactile sensing detection.

[0059] Specifically, the three-dimensional information within the semi-ellipsoidal shell-shaped flexible film 12 can be obtained as follows:

[0060] Three sets of RGB light sources 35 of different colors are installed on the support 34 by the detection element to illuminate the semi-ellipsoidal shell-shaped flexible film 12.

[0061] Camera 32 acquires color and shadow information of the inner surface of the semi-ellipsoidal shell-shaped flexible film 12;

[0062] The spatial three-dimensional information of the tactile deformation field is reconstructed from the reflection image of the inner surface.

[0063] Specifically, obtaining the three-dimensional information within the semi-ellipsoidal shell-shaped flexible film 12 can also be achieved by using a binocular camera 32 with binocular stereo vision, a structured light camera with structured light, or a TOF camera with TOF, and performing stereo reconstruction based on stereo vision.

[0064] According to one or more embodiments, a method for installing an optical deep-sea tactile sensor is disclosed, comprising the following steps:

[0065] The tactile sensing module 1 uses a limiting ring 13 to limit the installation on the semi-ellipsoidal shell-shaped flexible film 12;

[0066] After the limiting installation, the semi-ellipsoidal shell-shaped flexible film 12 with its ends facing upwards is vertically immersed in a container filled with liquid;

[0067] The glass window 11 is pushed vertically into the port of the semi-ellipsoidal shell-shaped flexible film 12 to complete the sealing and fixing of the glass window 11 on the semi-ellipsoidal shell-shaped flexible film 12.

[0068] The detection element is placed in the pressure-resistant housing 33 of the element storage chamber 3, and a support 34 is installed at the port of the pressure-resistant housing 33.

[0069] Place the O-ring 2 into the groove 333 of the pressure-resistant housing 33;

[0070] The component storage chamber 3 is evacuated by a vacuum pump, and the assembled tactile sensing module 1 is installed on one side of the support 34. It is then assembled and fixed by adsorption through the internal and external pressure difference.

[0071] The underwater connector 31 is sealed, and the internal air pressure of the component storage chamber 3 is restored by disassembling the underwater connector 31, and the components are disassembled.

[0072] The above installation method can avoid the generation of air bubbles when filling the membrane with liquid and ensure the internal liquid sealing under the requirement of compact structural design.

[0073] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An optical deep-sea tactile sensor characterized by: It comprises a tactile perception module (1), an O-shaped ring (2), and an element storage cabin (3). The tactile perception module (1) comprises a semi-elliptical shell type flexible film (12), a limiting ring (13) sleeved on the semi-elliptical shell type flexible film (12), and a glass window (11) sealingly connected to the semi-elliptical shell type flexible film (12); a liquid that offsets external hydrostatic pressure is filled between the semi-elliptical shell type flexible film (12) and the glass window (11). The element storage cabin (3) comprises a pressure-resistant shell (33) fixedly connected to the tactile perception module (1) through the limiting ring (13), a detection element installed in the pressure-resistant shell (33), and a support (34) installed on the port of the pressure-resistant shell (33) to support the glass window (11). The port of the pressure-resistant shell (33) is provided with a groove (333) for the O-shaped ring (2) to be clamped and sealed around the support (34). The detection element comprises a camera (32), and the surface of the support (34) is provided with a through hole for the camera (32) to pass through and detect.

2. The optical deep-sea tactile sensor according to claim 1, characterized in that: The semi-elliptical shell type flexible film (12) comprises a semi-elliptical film and a mounting ring connected integrally, and the inner side wall of the mounting ring is circumferentially provided with a semi-spherical protrusion (122) for sealingly abutting the glass window (11).

3. The optical deep-sea tactile sensor according to claim 2, characterized in that: The edge of the mounting ring extends outwardly and circumferentially to have a boss, and a plurality of limiting holes (121) are formed in the boss. The end of the limiting ring (13) protrudes a limiting block (131) clamped in the limiting hole (121). The port of the pressure-resistant shell (33) is provided with a clamping groove (332) for the limiting block (131) to be assembled, and the clamping groove (332) and the limiting block (131) are continuously provided with a threaded hole for a screw to pass through and be fixedly installed.

4. The optical deep-sea tactile sensor according to claim 1, characterized in that: The rear side of the pressure-resistant shell (33) is provided with an underwater connector (31) connected to the detection element in the cabin.

5. A sensing method based on the optical deep-sea tactile sensor according to claim 1, characterized by, It comprises the following steps: The tactile sensor is assembled on a deep-sea robot, the semi-elliptical shell type flexible film (12) simulates the finger tip to perceive external contact information, and contact deformation is generated when external force is applied to the semi-elliptical shell type flexible film (12); The camera (32) obtains three-dimensional information in the semi-elliptical shell type flexible film (12) through the glass window (11); The signal is transmitted through the underwater connector (31) to perform signal analysis and processing, and the tactile sensing detection is completed.

6. The sensing method of claim 5, wherein, The three-dimensional information in the semi-elliptical shell type flexible film (12) is obtained by: reconstructing the spatial three-dimensional information of the tactile deformation field by photometric stereo method, using a common camera (32) and different color RGB light sources (35), or reconstructing the spatial three-dimensional information of the tactile deformation field by a stereoscopic vision method, including any one of binocular stereoscopic vision method, structured light method, and TOF method, and correspondingly, the built-in camera (32) of the sensor is a binocular camera, a structure camera, or a TOF camera.

7. A method of installing the deep-sea tactile sensor according to claim 1, characterized by, It comprises the following steps: The limiting ring (13) of the tactile perception module (1) is used to limit and install the semi-elliptical shell type flexible film (12). The semi-elliptical shell type flexible film (12) is vertically immersed in the container filled with liquid after the limiting installation; The glass window (11) is pushed into the port of the semi-elliptical shell type flexible film (12) in the vertical direction, and the sealing and fixing of the glass window (11) on the semi-elliptical shell type flexible film (12) is completed; The detection element is placed in the pressure-resistant shell (33) of the element storage cabin (3), and a support (34) is installed at the port of the pressure-resistant shell (33); The O-ring (2) is placed in the groove (333) of the pressure-resistant shell (33); The element storage cabin (3) is vacuumized by the vacuumizing equipment, and the assembled tactile perception module (1) is installed on one side of the support (34), and is assembled and fixed after being adsorbed by the internal and external pressure difference; The underwater connector (31) is sealed, the internal pressure of the element storage cabin (3) is restored by disassembling the underwater connector (31), and the components are disassembled.

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