An optical fiber type underwater robot posture sensing device and method

Abstract

The application provides a fiber underwater robot posture sensing device and method. The device comprises a plurality of fiber Bragg grating sensors, a base, flexible silica gel, an omnidirectional rotatable transmission shaft, a spring and a stress sensing ball, the plurality of fiber Bragg grating sensors are embedded in the flexible silica gel; the flexible silica gel is placed in a circular base and transmits the force in the vertical direction of the stress sensing ball to the plurality of fiber Bragg grating sensors as a medium; the base is separated from the lower rotatable transmission shaft; the omnidirectional rotatable transmission shaft, the spring and the stress sensing ball form an elastic linkage system. The device is installed on the upper surface of the robot, when the posture of the robot deviates, the elastic device connected by the spring and the stress sensing ball slides on the entire flexible silica gel, the stress sensing ball extrudes the flexible silica gel, thereby causing the wavelength of the fiber Bragg to change, and the position of the stress sensing ball can be obtained by using a posture analysis model based on deep learning, so that different postures of the robot can be sensed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of touch pressure sensing, in particular, especially relates to a fiber-optic underwater robot posture sensing device and method. BACKGROUND

[0002] With the continuous progress of science and technology, underwater robots play an important role in the fields of ocean exploration, seabed resource development, environmental monitoring, etc. However, due to the complex and changeable marine environment, natural factors such as water flow, ocean current and dark current can easily cause the posture of the underwater robot to deviate, thereby affecting its working efficiency and the accuracy of task execution.

[0003] Traditional posture detection methods mainly rely on inertial sensors or gyroscopes and other devices. However, these devices are easily disturbed in underwater environments and are difficult to accurately capture subtle changes in posture. At the same time, factors such as high pressure, high humidity and corrosion in underwater environments also pose a serious challenge to the performance of these devices.

[0004] Prior art one

Patent No. CN202311343170.5, discloses a flexible arm surface force and its own posture sensing scheme based on multiple fiber Bragg gratings

[0005] Prior art two

Patent No. CN201910128253.X, discloses a hand posture sensing glove based on optical fiber

[0006] Inertial sensors are usually composed of accelerometers, gyroscopes and magnetometers. Accelerometers measure linear acceleration, gyroscopes measure angular velocity, and magnetometers provide a heading reference. By fusing and processing data from these sensors, the attitude information of an object can be calculated. However, during long-term use, sensor data from inertial sensors will drift and accumulate errors, resulting in inaccurate posture calculation results. At the same time, the magnetometer in the inertial sensor is easily disturbed by the environmental magnetic field, so in areas with strong magnetic fields, the accuracy of posture measurement is not high.

[0007] In addition, in a high dynamic environment, the measurement accuracy and stability of the inertial sensor will decrease, making it difficult to capture subtle attitude changes. Gyroscopes use the principle of angular momentum conservation to calculate the attitude change of an object by detecting its angular velocity. However, over a long period of use, gyroscopes may exhibit drift, and sensor noise may also affect the accuracy of attitude calculation.

[0008] In addition, temperature changes can affect the performance of gyroscopes, and temperature compensation is needed to ensure measurement accuracy. Traditional attitude detection systems usually require multiple sensors to work together, and the data fusion algorithm is complex, making system integration difficult and requiring a high level of operator experience. SUMMARY

[0009] According to the above technical problems, a fiber-optic underwater robot attitude sensing device and method are provided. The present application is based on the principle that the fiber Bragg wavelength shifts due to stress stimulation, and uses a deep learning model to establish the relationship between wavelength changes, indentation position, sliding trajectory and attitude changes to sense the attitude of the underwater robot.

[0010] The technical means adopted by the present application are as follows:

[0011] A fiber-optic underwater robot attitude sensing device, comprising: a plurality of fiber Bragg grating sensors, a base, a flexible silicone, an omnidirectional rotatable transmission shaft, a spring and a stress sensing ball, wherein:

[0012] The plurality of fiber Bragg grating sensors are embedded in the flexible silicone and are used to transmit the fiber Bragg wavelength changes caused by the vertical component of the stress sensing ball in real time;

[0013] The flexible silicone is placed in a circular base and is in direct contact with the stress sensing ball when in use, acting as a medium to transmit the force in the vertical direction of the stress sensing ball to the plurality of fiber Bragg grating sensors;

[0014] The omnidirectional rotatable transmission shaft is separate from the upper base and is used to drive the elastic device formed by the spring and the stress sensing ball to slide on the entire flexible silicone;

[0015] The spring is connected to the omnidirectional rotatable transmission shaft and the stress sensing ball and is used to stretch and contract to make the stress sensing ball slide when the attitude of the underwater robot deviates, and then a deep learning-based attitude analysis model is used to obtain the position of the stress sensing ball, thereby sensing different attitudes of the robot;

[0016] The stress sensing ball is used to apply pressure to the flexible silicone.

[0017] Further, the plurality of fiber Bragg grating sensors are provided in 19 sets and are distributed in three strings of optical fibers, wherein:

[0018] 9 fiber Bragg grating sensors are distributed in the outermost circle of optical fibers, 6 fiber Bragg grating sensors are distributed in the second circle of optical fibers, and 4 fiber Bragg grating sensors are distributed in the innermost circle of optical fibers; the distance between the fiber Bragg grating sensors is selected according to the size of the flexible silica gel, and the arrangement mode considers the cross-sensing between the multiple fiber Bragg grating sensors.

[0019] Further, the fiber type underwater robot posture sensing device further comprises a transparent protective dome for sealing and protecting the internal device, and also for avoiding the stress sensing ball from being out of the sensing range of the flexible silica gel due to large offset force.

[0020] Further, the transparent protective dome is threadedly connected with the circular base, so as to realize stable connection and ensure waterproof performance.

[0021] Further, the flexible silica gel is polydimethylsiloxane and silicone resin, and the multiple fiber Bragg grating sensors are located at the position of one half of the thickness of the flexible silica gel.

[0022] Further, the spring is a linear compression spring, which provides appropriate reaction force when the stress sensing ball slides, and ensures that the stress sensing ball is in good contact with the flexible silica gel.

[0023] Further, the stress sensing ball is made of a mixture of epoxy resin and iron powder.

[0024] The application also provides an underwater robot posture sensing method based on the fiber type underwater robot posture sensing device, which comprises the following steps:

[0025] S1, the underwater robot occurs posture offset:

[0026] The fiber type underwater robot posture sensing device is loaded on the underwater robot, when the underwater robot occurs posture offset, the force in the offset direction drives the elastic device composed of the omnidirectional rotatable transmission shaft, the spring and the stress sensing ball to rotate, the spring stores the energy in the offset process, and appropriate reaction force is provided when the stress sensing ball slides, so that the stress sensing ball is in good contact with the flexible silica gel.

[0027] S2, the fiber Bragg grating sensor transmits data:

[0028] The flexible silica gel is pressed in the vertical direction of the stress sensing ball, so that the grating area of the plurality of fiber Bragg grating sensors embedded therein is extruded, the grating pitch changes, the refractive index of the optical fiber changes, the fiber Bragg wavelength shifts, the shift amount of the wavelength is taken as input data, and is transmitted to a deep learning model trained to identify the position of the indentation, so as to predict the position. The deep learning model for identifying the position of the indentation is an MLP classification model, three hexagonal virtual grids are translated and superimposed on the flexible silica gel for position segmentation and prediction, each hexagonal grid is composed of 37 hexagons, the number of grids after translation and superimposition of the three virtual grids is 108, and the position of the applied pressure is determined by the weighted center of gravity of each grid. Among them, the position recognition accuracy of a single hexagonal grid is 96.6%, 97.2% and 96.2% respectively, and the position recognition accuracy of the finer grid after superposition is 98.2%;

[0029] S3, sensing the attitude of the underwater robot:

[0030] After the prediction is completed, the sliding track of the stress sensing ball on the flexible silica gel is obtained; the sliding track is taken as input data and transmitted to an attitude analysis model, so as to sense the attitude of the underwater robot.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] 1. The optical fiber type underwater robot attitude sensing device provided by the present application adopts fiber Bragg grating as a sensor, which has high sensitivity, fast response speed, high temperature resistance and anti-electromagnetic interference, is more suitable for complex underwater environment, and can accurately sense the attitude of the underwater robot.

[0033] 2. The optical fiber type underwater robot attitude sensing device provided by the present application has the advantages of simple structure, accurate sensing, simple sensing process and the like.

[0034] Based on the above reasons, the present application can be widely popularized in the field of touch pressure sensing and the like. BRIEF DESCRIPTION OF DRAWINGS

[0035] 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 the prior art description will be briefly introduced. 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.

[0036] Figure 1 It is a structural schematic diagram of the optical fiber type underwater robot attitude sensing device of the present application.

[0037] Figure 2The distribution diagram of a plurality of fiber Bragg grating sensors in the optical fiber underwater robot posture sensing device.

[0038] In the figure: 1, a plurality of fiber Bragg grating sensors; 2, a base; 3, flexible silica gel; 4, an omnidirectional rotatable transmission shaft; 5, a spring; 6, a stress sensing ball; 7, a circular base; 8, a fiber string; 9, a transparent protective dome. DETAILED DESCRIPTION

[0039] 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 drawings and in combination with the embodiments.

[0040] 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, rather than 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.

[0041] It should be noted that the terms used herein are only for describing specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a reference to the presence of a feature, step, operation, device, component and / or combinations thereof.

[0042] Unless specifically stated otherwise, the relative arrangement of components and steps, numerical expressions, and numerical values set forth in the various examples herein are not limiting of the scope of the application. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and not of limitation. The detailed description of the exemplary embodiments should be considered in connection with the accompanying drawings, and not in a hypertext transfer protocol (HTTP) context. The technology, methods, and devices known to those of ordinary skill in the art can not be discussed in detail, but should be considered as part of the authorized description. In all examples shown and discussed herein, any specific value should be interpreted as merely illustrative, not as a limitation. Therefore, other examples of the exemplary embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so further discussion is not necessary once an item is defined in one drawing.

[0043] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0044] 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.

[0045] 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.

[0046] like Figure 1 As shown, this invention provides a fiber optic underwater robot attitude sensing device, comprising: multiple fiber Bragg grating sensors 1, a base 2, flexible silicone 3, an omnidirectional rotatable drive shaft 4, a spring 5, and a stress sensing ball 6, wherein:

[0047] The plurality of fiber Bragg grating sensors 1 are embedded in flexible silicone 3 and are used to transmit in real time the fiber Bragg wavelength change caused by the component force of the stress sensing ball 6 in the vertical direction.

[0048] The flexible silicone 3 is placed in the circular base 7 and comes into direct contact with the stress sensing ball 6 during use, serving as a medium to transmit the force in the vertical direction of the stress sensing ball 6 to multiple fiber Bragg grating sensors 1.

[0049] The omnidirectional rotatable transmission shaft 4 is separated from the upper base 2 and is used to drive the elastic device formed by the spring 5 and the stress sensing ball 6 to slide on the entire flexible silicone 3.

[0050] The spring 5 is connected to the omnidirectional rotatable transmission shaft 4 and the stress sensing ball 6. It is used to extend and retract to make the stress sensing ball 6 slide when the underwater robot's posture changes. Then, the position of the stress sensing ball 6 is obtained by using a posture analysis model based on deep learning, thereby sensing the different postures of the robot.

[0051] The stress-sensing ball 6 is used to apply pressure to the flexible silicone 3.

[0052] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 As shown, there are 19 fiber Bragg grating sensors 1, distributed in three fiber strings 8, wherein:

[0053] Nine fiber Bragg grating sensors 1 are distributed in the outermost ring of optical fibers, six fiber Bragg grating sensors 1 are distributed in the second ring of optical fibers, and four fiber Bragg grating sensors 1 are distributed in the innermost ring of optical fibers. The distance between the fiber Bragg grating sensors 1 is selected according to the size of the flexible silicone 3, and the arrangement takes into account the cross-sensing between multiple fiber Bragg grating sensors 1.

[0054] In specific implementation, as a preferred embodiment of the present invention, please refer to [reference needed]. Figure 1 The fiber optic underwater robot attitude sensing device also includes a transparent protective dome 9, which is used to seal and protect the internal devices, and also to prevent the stress sensing ball 6 from leaving the sensing range of the flexible silicone 3 due to large offset force.

[0055] In a specific implementation, as a preferred embodiment of the present invention, the transparent protective dome 9 and the circular base 7 are connected by threads to achieve a stable connection and ensure waterproof performance.

[0056] In a specific implementation, as a preferred embodiment of the present invention, the flexible silicone 3 is made of polydimethylsiloxane and silicone resin, and is 16 mm thick, with multiple fiber Bragg grating sensors 1 located at the 8 mm thick position of the flexible silicone.

[0057] In a specific implementation, as a preferred embodiment of the present invention, the spring 5 is a linear compression spring, which provides an appropriate reaction force when the stress sensing ball 6 slides, ensuring good contact between the stress sensing ball 6 and the flexible silicone 3.

[0058] In a specific implementation, as a preferred embodiment of the present invention, the stress sensing ball 6 is a mixture of epoxy resin and iron powder cured and weighs 0.5 Newtons.

[0059] This invention also provides a method for underwater robot attitude perception based on the aforementioned fiber optic underwater robot attitude perception device, comprising:

[0060] S1. The underwater robot experiences a posture shift:

[0061] The fiber optic underwater robot attitude sensing device is mounted on the underwater robot. When the underwater robot deviates in attitude, the force in the direction of deviation will drive the omnidirectional rotatable transmission shaft 4 and the elastic device composed of the spring 5 and the stress sensing ball 6 connected to it to rotate. The spring 5 compresses and stores the energy of the deviation process and provides appropriate reaction force when the stress sensing ball 6 slides, so that the stress sensing ball 6 can make good contact with the flexible silicone 3.

[0062] S2, Fiber Bragg grating sensor transmits data:

[0063] The flexible silicone 3 is compressed by the force perpendicular to the stress-sensing ball 6, causing the grating regions of the multiple fiber Bragg grating sensors 1 embedded within it to be squeezed, resulting in a change in the grating pitch. This causes a change in the refractive index of the fiber, leading to a shift in the fiber Bragg wavelength. The wavelength shift is used as input data and transmitted to a trained deep learning model for identifying the indentation location for position prediction. This deep learning model for identifying the indentation location is an MLP classification model. It uses three hexagonal virtual grids, translated and superimposed on the flexible silicone 3, to segment and predict the location. Each hexagonal grid consists of 37 hexagons, and the number of grids after translation and superposition of the three virtual grids is 108. The location of the applied pressure is determined by the weight center of each grid. The position recognition accuracy of a single hexagonal grid is 96.6%, 97.2%, and 96.2%, respectively. The position recognition accuracy using the more refined grid after superposition is 98.2%.

[0064] S3. Sensing the underwater robot's attitude:

[0065] After the prediction is completed, the sliding trajectory of the stress sensing ball 6 on the flexible silicone 3 is obtained; the sliding trajectory is used as input data and transmitted to the attitude analysis model to perceive the attitude of the underwater robot.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fiber optic underwater robot attitude sensing device, characterized in that, include: The system comprises multiple fiber Bragg grating sensors (1), a base (2), flexible silicone (3), an omnidirectional rotatable drive shaft (4), a spring (5), and a stress sensing ball (6), wherein: The plurality of fiber Bragg grating sensors (1) are embedded in flexible silicone (3) for real-time transmission of the fiber Bragg wavelength change caused by the component force of the stress sensing ball (6) in the vertical direction. The flexible silicone (3) is placed in a circular base (7) and comes into direct contact with the stress sensing ball (6) during use. It serves as a medium to transmit the force in the vertical direction of the stress sensing ball (6) to multiple fiber Bragg grating sensors (1). The omnidirectional rotatable drive shaft (4) is separated from the upper base (2) and is used to drive the elastic device formed by the spring (5) and the stress sensing ball (6) to slide on the entire flexible silicone (3); The spring (5) is connected to the omnidirectional rotatable transmission shaft (4) and the stress sensing ball (6). It is used to extend and retract to make the stress sensing ball (6) slide when the underwater robot's posture deviates. Then, the position of the stress sensing ball (6) is obtained by using a posture analysis model based on deep learning, thereby sensing the different postures of the robot. The stress-sensing ball (6) is used to apply pressure to the flexible silicone (3).

2. The fiber optic underwater robot attitude sensing device according to claim 1, characterized in that, The plurality of fiber Bragg grating sensors (1) are provided in a total of 19 units, distributed in three fiber strings (8), wherein: Nine fiber Bragg grating sensors (1) are distributed in the outermost ring of optical fibers, six fiber Bragg grating sensors (1) are distributed in the second ring of optical fibers, and four fiber Bragg grating sensors (1) are distributed in the innermost ring of optical fibers. The distance between the fiber Bragg grating sensors (1) is selected according to the size of the flexible silicone (3), and the arrangement takes into account the cross-sensing between multiple fiber Bragg grating sensors (1).

3. The fiber optic underwater robot attitude sensing device according to claim 1, characterized in that, The fiber optic underwater robot attitude sensing device also includes a transparent protective dome (9) for sealing and protecting the internal devices, and also to prevent the stress sensing ball (6) from leaving the sensing range of the flexible silicone (3) due to large offset force.

4. The fiber optic underwater robot attitude sensing device according to claim 3, characterized in that, The transparent protective dome (9) and the circular base (7) are connected by threads to achieve a stable connection and ensure waterproof performance.

5. The fiber optic underwater robot attitude sensing device according to claim 1, characterized in that, The flexible silicone (3) is composed of polydimethylsiloxane and silicone resin, and multiple fiber Bragg grating sensors (1) are located at half the thickness of the flexible silicone (3).

6. The fiber optic underwater robot attitude sensing device according to claim 1, characterized in that, The spring (5) is a linear compression spring that provides appropriate elastic force when the stress sensing ball (6) slides, ensuring good contact between the stress sensing ball (6) and the flexible silicone (3).

7. The fiber optic underwater robot attitude sensing device according to claim 1, characterized in that, The stress sensing ball (6) is a mixture of epoxy resin and iron powder that has been cured.

8. A method for underwater robot attitude perception based on the fiber optic underwater robot attitude perception device according to any one of claims 1-7, characterized in that, include: S1. The underwater robot experiences a posture shift: The fiber optic underwater robot attitude sensing device is mounted on the upper surface of the underwater robot. When the underwater robot deviates in attitude, the force in the direction of deviation will drive the omnidirectional rotatable transmission shaft (4) and the elastic device consisting of the spring (5) and the stress sensing ball (6) connected to it to rotate. The spring (5) compresses and stores the energy of the deviation process and provides appropriate elastic force when the stress sensing ball (6) slides, so that the stress sensing ball (6) makes good contact with the flexible silicone (3). S2, Fiber Bragg grating sensor transmits data: The flexible silicone (3) is compressed by the force in the vertical direction of the stress sensing ball (6), which causes the grating area of ​​the multiple fiber Bragg grating sensors (1) embedded in it to be squeezed, the grating pitch to change, which in turn causes the refractive index of the fiber to change and the fiber Bragg wavelength to shift. The wavelength shift is used as input data and transmitted to the trained deep learning model for identifying the indentation position to predict the position. The deep learning model for identifying the indentation position is an MLPs classification model. Three hexagonal virtual grids are translated and superimposed on the flexible silicone (3) to segment and predict the position. Each hexagonal grid consists of 37 hexagons. The number of grids after the translation and superposition of the three virtual grids is 108. The position of the pressure is determined by the weight center of each grid. The position recognition accuracy of a single hexagonal grid is 96.6%, 97.2% and 96.2%, respectively. The position recognition accuracy of the superimposed finer grid is 98.2%. S3. Sensing the underwater robot's attitude: After the prediction is completed, the sliding trajectory of the stress sensing ball (6) on the flexible silicone (3) is obtained. The sliding trajectory is used as input data and transmitted to the attitude analysis model to perceive the attitude of the underwater robot.

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