A hand motion capture device and system based on multi-core fiber grating array sensing

Abstract

A hand action capture device and system based on a multi-core fiber grating array sensor, characterized by comprising: a multi-channel fiber grating demodulator, a multi-core fiber grating array, a communication transmission module, a computer solving module, an image rendering and display module, and a flexible glove. The multi-core fiber grating array is arranged on the side of the fingers, outlines the finger contour, the fiber grating group on the side of the fingers is used for sensing the bending angle of each finger joint; the fiber grating group between the fingers is arranged in a U shape and is used for sensing the opening and closing angle between the fingers; the fiber grating group at the metacarpophalangeal joint of each finger on the back of the hand is used for sensing the bending and stretching angle of the palm. The scheme provided by the utility model has the advantages of simple device, easy arrangement, high precision, high comfort, small error, fast response speed, no electromagnetic interference, and no influence of hand flexibility by the sensor, and can comprehensively and carefully capture hand actions.

Description

Technical Field

[0001] This utility model relates to the field of fiber optic sensing technology and hand motion capture, specifically to a hand motion capture device and system based on multi-core fiber optic grating array sensing. Background Technology

[0002] In recent years, human-computer interaction (HCI) technology has been developing rapidly, demonstrating enormous application potential in various fields such as medical surgery, industrial and mining sectors, scene simulation, and e-sports games. However, traditional devices like keyboards and joysticks suffer from poor flexibility and a lack of realism in HCI applications. Therefore, capturing human gestures more vividly and quickly is a crucial issue. Due to the diversity and flexibility of human hand gestures, dynamic gesture acquisition is a hot topic in HCI technology, with the key aspects being the recognition speed and effectiveness of dynamic gesture acquisition. Existing dynamic gesture acquisition devices include inertial sensors, high-speed cameras, data gloves, and exoskeleton robotic hands. However, inertial sensors are greatly affected by electromagnetic interference, making it difficult to accurately reflect hand posture and dynamic gestures, resulting in large errors and low accuracy. While high-speed cameras achieve satisfactory accuracy in hand posture acquisition, recognition accuracy drops significantly in practical use if obstructed. They are also not portable for engineering applications. Acquiring hand posture is costly, with complex algorithms requiring extensive training data to ensure recognition effectiveness. Data gloves have varying advantages and disadvantages depending on the type of sensor used; typically, a single data glove contains multiple different types of sensors, and their deployment is complex due to the physical size of the sensors, the connection methods between them, and electromagnetic interference. Exoskeleton robotic hands or other external structure-based dynamic gesture acquisition devices detect hand joint movements by strategically placing precise mechanical components and potentiometers at the hand joints. These devices are structurally complex, costly, and require numerous mechanical components, resulting in large size, difficulty in achieving precise hand posture acquisition, low user comfort, and significant time and effort required for maintenance.

[0003] Fiber optic shape sensing technology is an emerging technology that has developed in recent years. It utilizes optical fibers, such as grating array fibers and multi-core fibers, to monitor and invert the shape of objects. Fiber optic sensors offer advantages such as small size, light weight, ease of packaging, resistance to electromagnetic interference, and high sensitivity. In the aerospace field, fiber optic shape sensing technology has been used to monitor changes in aircraft wings, improving aircraft safety. In the medical field, it is used to precisely deliver instruments or medications to the required sites during interventional surgery. In the field of intelligent robotics, several existing technologies have also been disclosed for acquiring hand gestures using fiber optic shape sensing technology.

[0004] Existing technology discloses a data glove based on fiber Bragg gratings. Fiber Bragg gratings are adhered to shape memory alloy wires using epoxy resin and placed on the back of the hand. Each fiber Bragg grating corresponds to a specific joint on the finger, forming a fiber Bragg grating-based bending sensor. However, in this approach, the bending of the finger joints directly acts on the fiber Bragg gratings adhered to the shape memory alloy wires. During measurement, the bending of the fingers causes skin stretching, and the force generated by the bending is directly applied to the fiber Bragg gratings, subjecting them to significant axial stress. The wavelength of the fiber Bragg grating shifts considerably with finger bending. Therefore, this approach requires a relatively large wavelength spacing between the three fiber Bragg gratings on each finger to ensure a certain wavelength interval between different fiber Bragg gratings even when the finger bends. Consequently, it is impossible to further add fiber Bragg gratings for temperature compensation. Ultimately, by measuring the shift in the center wavelength of the fiber Bragg gratings, it becomes impossible to distinguish between temperature and strain. Therefore, this approach suffers from significant systematic errors. Furthermore, because the elongation of optical fiber is much lower than that of skin, the aforementioned sensing scheme severely restricts finger movement. During large finger bends, the fiber grating is difficult to stretch further, limiting the range of finger movement, affecting sensing accuracy and linearity, and causing measurement errors; even worse, it can lead to the fiber grating breaking. If the fiber grating is attached away from the finger joint, the strain on the fiber grating will be significantly reduced under the same degree of finger bend, and the wavelength shift will also be greatly reduced. The difference in wavelength change between the joint and off-joint positions is very large, resulting in a significant decrease in measurement sensitivity when off-joint. Due to the complexity of hand gesture changes, the signal-to-noise ratio decreases during measurement, leading to significant bending measurement errors. Therefore, this scheme requires strict control over the fiber grating attachment point; even a slight deviation will introduce substantial measurement errors.

[0005] Existing technology also discloses a hand gesture recognition wearable device and system based on seven-core fiber optic sensing. The device employs multiple seven-core fiber optic sensing units, a multiplexer, a demultiplexer, multiple photodetectors, and an information processing module. It utilizes the intermodal interference of the multi-core fiber to achieve strain sensing. In this scheme, a seven-core fiber optic sensing unit is positioned at each finger joint to detect the finger bending angle; another seven-core fiber optic sensing unit is positioned along the direction extending from the palm towards the fingers on the wearable body to detect the palm bending angle and direction. Fiber optic sensors based on intermodal interference exhibit complex interference spectra. This scheme requires the use of a deep learning neural network model to learn feature vectors from the sensing data in order to match these feature vectors with changes in the hand gesture to be recognized, thus enabling gesture recognition. This scheme cannot accurately calculate the angle of each hand joint; it can only roughly classify the data into a fixed gesture model using deep learning methods, failing to meet the accuracy requirements for hand motion capture. Furthermore, the gesture recognition of this scheme requires a large number of training samples, and any deviation in the deployment method will affect the final gesture recognition result, causing gesture reconstruction error.

[0006] The disclosed technologies mentioned above share a common problem: due to limitations in deployment methods and demodulation principles, the dynamic gestures that can be acquired in real time are limited. Influenced by the sensor deployment method, the solution disclosed in prior art 1 can only detect finger bending, while the solution disclosed in prior art 2 can detect both finger and palm bending postures. However, it cannot accurately acquire more complex hand postures in real time, such as highly precise and complex postures like finger spread and the bending angle of each finger joint.

[0007] In order to more conveniently, flexibly and accurately acquire and recognize human hand posture features and dynamic gesture trajectories, and in order to effectively promote the development and application of human-computer interaction technology, there is an urgent need for a device and system that is easy to deploy, real-time, highly sensitive, has low error, high accuracy, simple to install, highly comfortable, and is not subject to electromagnetic interference for real-time and accurate capture of hand movements.

[0008] This invention provides a hand motion capture device and system based on a multi-core fiber Bragg grating array (FBG) sensor, which can accurately capture hand movements using FBG sensing. The device uses a FBG array to outline the finger contours. FBG groups located on the sides of the fingers sense the bending angles of each finger joint; FBG groups between the fingers, arranged in a U-shape, sense the opening and closing angles between the fingers; and FBG groups located at the metacarpophalangeal joints of each finger on the back of the hand sense the bending and extension angles of the palm. This invention overcomes the difficulties of capturing complex hand postures, requiring high sensor placement accuracy, and dealing with issues such as FBG chirping, breakage, and limited range of motion during hand movements, achieving high-precision and comprehensive hand motion capture. Summary of the Invention

[0009] The solution adopted by this utility model to solve the technical problem is as follows.

[0010] A hand motion capture device and system based on multi-core fiber Bragg grating array sensing includes a multi-channel fiber Bragg grating demodulator, a multi-core fiber Bragg grating array, a communication transmission module, a computer processing module, an image rendering and display module, and a flexible glove.

[0011] The multi-channel fiber Bragg grating demodulator is used to measure the wavelength change of each fiber Bragg grating in a multi-core fiber Bragg grating array in real time.

[0012] The multi-core fiber grating array is composed of multiple fiber grating arrays arranged longitudinally and then bonded together; the fiber grating array is fabricated using an integrated in-line writing method; each fiber grating array contains multiple fiber gratings distributed along the fiber axis, the spacing between the fiber gratings corresponds to the sensing points of each joint, and the positional difference does not exceed ±1 mm; multiple fiber gratings of different cores at the same position in the multi-core fiber grating array form a group, and the positional difference of the fiber gratings in different cores in each group does not exceed ±1 m.

[0013] The multi-core fiber grating array is deployed on a flexible glove.

[0014] The aforementioned flexible glove is a wearable flexible glove with elasticity.

[0015] The communication transmission module is used for real-time communication with the multi-channel fiber Bragg grating demodulator.

[0016] The multi-channel fiber Bragg grating demodulator communicates with the communication transmission module and has real-time testing and data acquisition functions, which are used to obtain the strain of each fiber Bragg grating in the multi-core fiber Bragg grating array in real time.

[0017] The computer calculation module has data analysis and processing functions. Based on the strain of each fiber grating in the multi-core fiber grating array deployed on the flexible glove, the bending angle and bending direction of each joint of the hand are obtained by calculating the curvature and bending direction of the multi-core fiber grating array, thereby realizing the capture of hand movements.

[0018] The image drawing and display module has a real-time drawing and display function for hand movements, which is used to display the hand shape reconstruction results and hand movement capture results, and dynamically display hand movements.

[0019] In order to achieve hand motion capture based on multi-core fiber grating array sensing, the multi-core fiber grating array is deployed on a flexible glove.

[0020] Preferably, the multi-core fiber Bragg grating array comprises 19 fiber Bragg grating groups.

[0021] Preferably, the number of fibers in the multi-core fiber Bragg grating array is 3; the arrangement method is as follows: the first multi-core fiber Bragg grating array includes 8 fiber Bragg gratings, starting from the wrist on the thumb side and arranged along the outer edge of the thumb. The first fiber Bragg grating is arranged longitudinally at the thumb's carpal joint and continues to be arranged along the outer edge of the thumb. The second fiber Bragg grating is arranged longitudinally at the thumb's second metacarpophalangeal joint. The third fiber Bragg grating is arranged longitudinally at the thumb's interphalangeal joint. The multi-core fiber Bragg grating array continues to be arranged along the outer edge of the thumb to the web of the hand. The fourth fiber Bragg grating is arranged laterally below the web of the hand on the back of the hand. At a distance of 0.2-1.5 cm, the multi-core fiber Bragg grating array is arranged in a U-shape upwards. The 5th fiber Bragg grating is located longitudinally at the metacarpophalangeal joint of the index finger on the back of the hand, continuing along the outer edge of the left side of the index finger. The 6th fiber Bragg grating is located longitudinally at the proximal interphalangeal joint of the outer edge of the left side of the index finger. The 7th fiber Bragg grating is located longitudinally at the distal interphalangeal joint of the outer edge of the left side of the index finger. The multi-core fiber Bragg grating array wraps around the fingertip of the index finger and continues along the outer edge of the right side of the index finger to the base. On the back of the hand, it continues to be arranged in a U-shape to the left to the base of the left side of the middle finger. The 8th fiber Bragg grating is located laterally between the index and middle fingers, 0.2-1.5 cm from the base. At a distance of cm; the second multi-core fiber Bragg grating array contains 7 fiber Bragg gratings, arranged from the wrist on the back of the hand towards the middle finger, reaching the metacarpophalangeal joint of the middle finger. The 9th fiber Bragg grating is arranged longitudinally, then continues upward along the left outer edge of the middle finger. The 10th fiber Bragg grating is arranged longitudinally at the proximal interphalangeal joint of the middle finger. The 11th fiber Bragg grating is located longitudinally at the distal interphalangeal joint of the middle finger, continuing along the outer edge of the middle finger, past the fingertip, and along the right outer edge of the middle finger to the base of the middle finger. It continues to the left in a U-shape on the back of the hand to the left base of the ring finger. The 12th fiber Bragg grating is located laterally between the middle and ring fingers, 0.2~1.5 cm from the base. At a distance of cm, the multi-core fiber Bragg grating array continues upwards, arranged along the left outer edge of the ring finger. The 13th fiber Bragg grating is arranged longitudinally at the proximal interphalangeal joint of the ring finger. The 14th fiber Bragg grating is arranged longitudinally at the distal interphalangeal joint of the ring finger, continuing along the outer edge of the ring finger, past the fingertip, and along the right outer edge of the ring finger to the base of the ring finger. On the back of the hand, it continues to be arranged in a U-shape to the left to the base of the left side of the ring finger. The 15th fiber Bragg grating is located laterally between the ring finger and the little finger, 0.2~1 cm from the base.At a distance of 5 cm; the third multi-core fiber grating array contains 4 fiber gratings, arranged from the wrist on the back of the hand towards the little finger, reaching the metacarpophalangeal joint of the little finger. The 16th fiber grating is arranged longitudinally, then moves upward and to the left, gradually transitioning to the left outer side of the little finger. Along the left outer edge of the little finger, the 17th fiber grating is arranged longitudinally at the proximal interphalangeal joint of the little finger. The 18th fiber grating is located longitudinally at the distal interphalangeal joint of the little finger, continuing along the outer edge of the little finger, passing the fingertip, and then along the right outer side of the little finger, reaching the base between the little finger and ring finger, gradually transitioning to the right side to the metacarpophalangeal joint of the ring finger. The fiber gratings are arranged longitudinally. The fiber gratings fit tightly against the hand, preventing excessive stretching that could cause excessive wavelength shift or chirping when the hand posture changes. The multi-core fiber grating array bends and changes with the hand gesture to capture hand movements.

[0022] Preferably, the multi-core fiber Bragg grating array is a single or multiple fiber Bragg gratings. Referring to the above arrangement, the number of fiber Bragg grating groups in each multi-core fiber Bragg grating array can be adjusted. The multi-core fiber Bragg grating array is arranged on the side of the finger to outline the finger contour. The fiber Bragg grating groups located on the side of the finger are used to sense the bending angle of each finger joint. The fiber Bragg grating groups between the fingers are arranged in a U-shape to sense the opening and closing angle between the fingers. The fiber Bragg grating groups located at the metacarpophalangeal joints of each finger on the back of the hand are used to sense the bending and extension angles of the palm.

[0023] Preferably, the fiber optic grating group located on the side of the finger, as described above, can be placed at the joint on the left or right outer side of the finger to sense the bending angle of each finger joint.

[0024] Preferably, the number of fiber Bragg gratings can be increased to achieve more precise hand motion capture.

[0025] Preferably, the number of fiber optic grating groups can be reduced to 15 groups. The fiber optic grating groups at the distal interphalangeal joints of the index, middle, ring, and little fingers can be eliminated. The movement of the distal interphalangeal joints can be compensated by calculating the kinematic model of the fingers. After the compensation is calculated, the movement of the entire hand can be captured.

[0026] Preferably, the multi-core fiber Bragg grating array is arranged as described above and fixed to the flexible glove with polymer adhesive.

[0027] Preferably, the multi-core fiber grating array can be encapsulated in a sleeve and then deployed on a flexible glove.

[0028] Preferably, the multi-core fiber grating array is a three-core fiber grating array, wherein the three cores of the three-core fiber grating array are arranged in a triangle and are arranged at 120° to each other, and the cores are numbered A, B and C respectively.

[0029] Preferably, the multi-core fiber grating array is composed of N+1 fiber grating arrays, with a central core and the remaining N cores evenly distributed around the central core.

[0030] A hand motion capture device and system based on multi-core fiber Bragg grating array sensing is disclosed. The connection between the multi-channel fiber Bragg grating demodulator, the multi-core fiber Bragg grating array, the communication transmission module, the computer processing module, and the image rendering and display module is as follows: the optical port of the multi-channel fiber Bragg grating demodulator is connected to the fiber core of each of the I, II, and III multi-core fiber Bragg grating arrays, respectively; the electrical port of the multi-channel fiber Bragg grating demodulator is connected to the communication transmission module; the output of the communication transmission module is connected to the input of the computer processing module; and the output of the computer processing module is connected to the image rendering and display module.

[0031] The beneficial effects of this utility model are as follows:

[0032] 1. This solution uses a multi-core fiber optic grating array as the sensing medium, which is laid out along the edge of each finger to outline the hand contour. The layout is strictly limited to the area between the palm and back sides, and is not laid directly on the joints. This can avoid excessive grating stretching, which may cause excessive grating wavelength shift or chirping, thus improving measurement accuracy.

[0033] 2. The proposed method for deploying a multi-core fiber Bragg grating array on a flexible glove effectively avoids restricting finger movement. Since the elongation of optical fiber is much lower than that of skin, directly placing the fiber optic sensor on the joint severely limits finger movement. During large finger bends, the fiber Bragg grating is not easily stretched further, affecting sensing accuracy and linearity, and causing measurement errors. This method effectively prevents the impact of skin stretching caused by finger bending on the fiber optic sensor during measurement, avoiding excessive axial stress on the fiber Bragg grating and allowing for more flexible hand motion capture.

[0034] 3. The multi-core fiber Bragg grating array deployment method proposed in this solution on flexible gloves effectively avoids the problem of significantly reduced measurement sensitivity caused by the fiber Bragg grating being attached off-center from the finger joints. This solution does not require strict control over the fiber Bragg grating attachment points; measurement sensitivity remains largely unchanged even within ±1 mm of the finger joint, reducing the stringent requirements for precise fiber optic sensor placement and greatly improving system feasibility.

[0035] 4. This solution uses a multi-core fiber Bragg grating array as the sensing medium. The multiple fiber Bragg gratings in each fiber Bragg grating group can compensate for each other, eliminating the influence of temperature and effectively solving the cross-effect of temperature and strain on the fiber Bragg grating, thereby improving the measurement accuracy of the system.

[0036] 5. The proposed deployment scheme includes fiber optic gratings located on the sides of the fingers to sense the bending angles of each finger joint; U-shaped fiber optic gratings between the fingers to sense the opening and closing angles between them; and fiber optic gratings located at the metacarpophalangeal joints of each finger on the back of the hand to sense the bending and extension angles of the palm. This scheme can accurately calculate the angles of each joint in the hand. Therefore, for complex hand posture and motion capture, such as highly precise and complex postures like finger spread and the bending angles of each finger joint, it can achieve real-time and accurate acquisition of hand movements.

[0037] 6. The multi-core fiber Bragg grating array proposed in this solution is compact, immune to electromagnetic interference, and features fast response, low error, and high accuracy. When selecting fiber Bragg grating sensors, different numbers of fiber cores, grating wavelengths, and grating spacings can be chosen as needed, offering flexibility and strong applicability.

[0038] 7. Based on the relationship model between the curvature and bending direction of the fiber Bragg grating array and the bending angle of the joint, this solution inputs the curvature and bending direction data collected in real time by the fiber Bragg grating array into the model to calculate the bending angle of each hand joint in real time. The method is simple, the algorithm has multiple choices, and the calculation is simple. It does not require a lot of time to train data. On the basis of realizing gesture recognition, it can also achieve accurate capture of dynamic gestures. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of a hand motion capture device and system based on a multi-core fiber optic grating array sensor.

[0040] Figure 2 This is a schematic diagram of the layout of a multi-core fiber Bragg grating array on a flexible glove.

[0041] Figure 3 This is a schematic diagram of the cross-section of a multi-core fiber grating array, preferably a three-core fiber grating array.

[0042] Figure 4 A schematic diagram of the cross-section of a multi-core fiber Bragg grating array, preferably an N+1 core fiber Bragg grating array. Detailed Implementation

[0043] The present invention will now be further described with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the hand motion capture device and system based on multi-core fiber grating array sensing includes a multi-channel fiber grating demodulator (1), a multi-core fiber grating array (2), a communication transmission module (3), a computer calculation module (4), an image drawing and display module (5), and a flexible glove (6).

[0045] The multi-channel fiber grating demodulator (1) is used to measure the wavelength change of each fiber grating in the multi-core fiber grating array (2) in real time.

[0046] The multi-core fiber grating array (2) is composed of multiple fiber grating arrays arranged longitudinally and then bonded together; the fiber grating array is fabricated using an integrated online writing method; each fiber grating array contains multiple fiber gratings distributed along the fiber axis, the spacing between the fiber gratings corresponds to the sensing points of each joint, and the positional difference does not exceed ±1 mm; multiple fiber gratings of different cores at the same position in the multi-core fiber grating array form a group, and the positional difference of the fiber gratings in different cores in each group does not exceed ±1 mm.

[0047] The multi-core fiber grating array (2) is arranged on the flexible glove (6).

[0048] The flexible glove (6) is a wearable flexible glove with elasticity.

[0049] The communication transmission module (3) is used to communicate with the multi-channel fiber optic demodulator (1) in real time.

[0050] The multi-channel fiber grating demodulator (1) communicates with the communication transmission module (3) and has real-time testing and data acquisition functions, which are used to obtain the strain of each fiber grating in the multi-core fiber grating array in real time.

[0051] The computer calculation module (4) has data analysis and processing functions. Based on the strain of each fiber grating in the multi-core fiber grating array (2) arranged on the flexible glove (6), the bending angle and bending direction of each joint of the hand are obtained by calculating the curvature and bending direction of the multi-core fiber grating array (2), thereby realizing the capture of hand movements.

[0052] The image drawing and display module (5) has the function of real-time drawing and display of hand movements, which is used to display the hand shape reconstruction results and hand movement capture results, and dynamically display hand movements.

[0053] Figure 2 This is a schematic diagram of the multi-core fiber grating array (2) on a flexible glove (6).

[0054] Preferably, the multi-core fiber grating array (2) contains 19 fiber grating groups.

[0055] Preferably, the multi-core fiber Bragg grating array (2) has 3 fiber gratings; the first multi-core fiber Bragg grating array includes 8 sets of fiber Bragg gratings, starting from the wrist on the thumb side and arranged along the outer edge of the thumb. Among them, the first set (201) of fiber Bragg gratings is arranged longitudinally at the thumb carpal joint and continues to be arranged along the outer edge of the thumb; the second set (202) of fiber Bragg gratings is arranged longitudinally at the thumb's second metacarpophalangeal joint; the third set (203) of fiber Bragg gratings is arranged longitudinally at the thumb's interphalangeal joint; the multi-core fiber Bragg grating array continues to be arranged along the outer edge of the thumb to the web between the thumb and index finger; and the fourth set (204) of fiber Bragg gratings is arranged laterally, located 0.2~1.5 cm below the web between the thumb and index finger on the back of the hand. At a distance of cm, the multi-core fiber grating array is arranged in a U-shape upwards. The fifth group (205) of fiber gratings is located longitudinally at the metacarpophalangeal joint of the index finger on the back of the hand, and continues to be arranged along the outer edge of the left side of the index finger. The sixth group (206) of fiber gratings is located longitudinally at the proximal interphalangeal joint of the outer edge of the left side of the index finger. The seventh group (207) of fiber gratings is located longitudinally at the distal interphalangeal joint of the outer edge of the left side of the index finger. The multi-core fiber grating array wraps around the fingertip of the index finger and continues to be arranged along the outer edge of the right side of the index finger to the base. On the back of the hand, it continues to be arranged in a U-shape to the left to the base of the left side of the middle finger. The eighth group (208) of fiber gratings is located laterally between the index and middle fingers, 0.2~1.5cm from the base. The second multi-core fiber grating... The fiber grating array comprises 7 fiber gratings, arranged from the wrist on the back of the hand towards the middle finger, reaching the metacarpophalangeal joint of the middle finger. The 9th group (209) fiber grating is arranged longitudinally, then continues upward along the left outer edge of the middle finger. The 10th group (210) fiber grating is arranged longitudinally at the proximal interphalangeal joint of the middle finger. The 11th group (211) fiber grating is located longitudinally at the distal interphalangeal joint of the middle finger, continuing along the outer edge of the middle finger, passing the fingertip, and then along the right outer edge of the middle finger to the base of the middle finger. It continues to the left in a U-shape on the back of the hand to the left base of the ring finger. The 12th group (212) fiber grating is located laterally between the middle and ring fingers, 0.2~1.5 meters from the base. At cm, the multi-core fiber grating array continues upward, along the left outer edge of the ring finger. The 13th group (213) fiber grating is arranged longitudinally at the proximal interphalangeal joint of the ring finger. The 14th group (214) fiber grating is arranged longitudinally at the distal interphalangeal joint of the ring finger. It continues to be arranged along the outer edge of the ring finger, past the fingertip, along the right outer edge of the ring finger to the root of the ring finger. It continues to be arranged in a U-shape to the left on the back of the hand to the root of the left side of the ring finger. The 15th group (215) fiber grating is located horizontally between the ring finger and the little finger, 0.2~1 cm from the root.At 5 cm; the third multi-core fiber grating array contains 4 fiber gratings, arranged from the back of the hand and wrist towards the little finger, to the metacarpophalangeal joint of the little finger, the 16th group (216) fiber grating is arranged longitudinally, then arranged to the upper left, gradually transitioning to the left outer side of the little finger, along the left outer edge of the little finger, the 17th group (217) fiber grating is arranged longitudinally, located at the proximal interphalangeal joint of the little finger, the 18th group (218) fiber grating is located longitudinally at the distal interphalangeal joint of the little finger, continuing to be arranged along the outer edge of the little finger, past the tip of the little finger and along the right outer side of the little finger, to the base of the little finger between the little finger and the ring finger, gradually transitioning to the right side to the metacarpophalangeal joint of the ring finger, the fiber grating is arranged longitudinally; this arrangement makes the fiber grating fit tightly against the hand, and when the hand posture changes, it can avoid excessive stretching that causes excessive grating wavelength shift or chirping phenomenon; as the hand gesture changes, the multi-core fiber grating array bends and changes, thereby capturing hand movements. .

[0056] Preferably, the multi-core fiber grating array (2) is a single or multiple fiber gratings. Referring to the above arrangement, the number of fiber grating groups in each multi-core fiber grating array can be adjusted. The multi-core fiber grating array (2) is arranged on the side of the finger to outline the finger contour. The fiber grating groups located on the side of the finger are used to sense the bending angle of each finger joint. The fiber grating groups between the fingers are arranged in a U-shape to sense the opening and closing angle between the fingers. The fiber grating groups located at the metacarpophalangeal joint of each finger on the back of the hand are used to sense the bending and extending angle of the palm.

[0057] Preferably, the fiber optic grating group located on the side of the finger, as described above, can be placed at the joint on the left or right outer side of the finger to sense the bending angle of each finger joint.

[0058] Preferably, the number of fiber Bragg gratings can be increased to achieve more precise hand motion capture.

[0059] Preferably, the number of fiber optic grating groups can be reduced to 15 groups. The fiber optic grating groups at the distal interphalangeal joints of the index, middle, ring, and little fingers can be eliminated. The movement of the distal interphalangeal joints can be compensated by calculating the kinematic model of the fingers. After the compensation is calculated, the movement of the entire hand can be captured.

[0060] Preferably, the multi-core fiber grating array (2) is arranged as described above and placed on the flexible glove (6), and then fixed with polymer glue.

[0061] Preferably, the multi-core fiber grating array (2) can be encapsulated in a sleeve and then placed on a flexible glove (6).

[0062] The following explanation uses two preferred multi-core fiber grating arrays (2) as examples.

[0063] Preferably, the multi-core fiber grating array (2) is a three-core fiber grating array, such as... Figure 3 As shown, the three fiber cores of the three-core fiber Bragg grating array are arranged in a triangle, with each core at a 120° angle to the others. The cores are numbered A, B, and C. The steps for achieving hand motion capture are as follows:

[0064] Step 1: Obtain the strain of each fiber grating in the three-core fiber grating array, and calculate the difference in strain between each group of fiber gratings in the three cores to eliminate the combined effect of temperature: ; ; ; These represent the strains experienced by the same group of fiber gratings located in fiber cores A, B, and C, respectively. These represent the strain differences between the fiber gratings in the same group located in fiber cores A, B, and C.

[0065] Step 2: Calculation of curvature and bending direction of the three-core fiber optic grating array: ; Where k is the curvature and d is the distance from the fiber core to the center of the optical fiber. The 120° symmetrical geometry originates from a three-core optical fiber. The angle of the fiber bending direction relative to core A is:

[0066] in This represents the arctangent function.

[0067] Step 3: Calibration of the relationship between joint bending angle and grating array curvature and bending direction. Obtain the joint bending angle, grating array curvature, and bending direction, and establish a one-to-one correspondence between the joint bending angle and grating array curvature and bending direction to create a model of the relationship between grating array curvature, bending direction, and joint bending angle.

[0068] Preferably, the relationship model between the curvature of the grating array and the bending direction to the joint bending angle can be established through linear regression, nonlinear fitting, and machine learning data fitting algorithms.

[0069] Step 4: Hand shape reconstruction and hand motion capture. Based on the relationship model between the curvature and bending direction of the three-core fiber grating array and the bending angle of the joints, the curvature and bending direction data collected in real time by the three-core fiber grating array are input into the relationship model to calculate the bending angle of each hand joint in real time, thereby realizing hand motion capture.

[0070] Preferably, the multi-core fiber Bragg grating array consists of N+1 fiber Bragg gratings, with a central core and N other cores evenly distributed around it. The steps for achieving hand motion capture are as follows:

[0071] Step 1: Calculate the strain difference of each fiber grating in the multi-core fiber grating array: In actual monitoring, fiber gratings are affected by both temperature and strain. Temperature has the same effect on all gratings in each fiber grating group. Based on the difference in strain between the fiber gratings in the surrounding cores and the fiber grating in the central core, the influence of temperature on the strain value of the fiber gratings in the surrounding cores is eliminated, and the strain difference at the m-th grating position of the n-th core is obtained. .

[0072] Step 2: Calculate the curvature and bending direction at the location of the fiber grating using the strain value. The relationship formula is: ; in Let be the strain difference between the position of the m-th fiber grating in the n-th fiber core and the position of the m-th fiber grating in the central fiber core, and D be the horizontal distance between the two symmetrical outer fiber cores. Let be the bending radius at the m-th fiber grating position of the n-th fiber core. Let N be the angle between the bending direction and the first fiber core, and N be the number of other fiber grating array cores on the outer side; the strain difference at the m-th fiber grating position of the n-th fiber core obtained in step two is... Substituting into the above formula, we obtain (N-1) equations. Solving these (N-1) equations simultaneously yields the bending radius at the m-th grating position of the n-th fiber core. The value, and the angle between the bending direction and the first fiber core. The value is given, where the first fiber core can be freely selected, and the other fiber grating cores around it are arranged counterclockwise from the first fiber core.

[0073] Step 3: The relationship between the joint bending angle and the curvature and bending direction of the fiber optic grating array is calibrated, which is the same as step 3 above for hand motion capture using a three-core fiber optic grating array.

[0074] Step 4: Hand shape reconstruction and hand motion capture. This is the same as step 4 above for hand motion capture using a three-core fiber optic grating array.

[0075] The working principle of this utility model is as follows: the optical port of the multi-channel fiber grating demodulator (1) is optically connected to the fiber cores of the I, II, and III multi-core fiber grating arrays (2); the electrical port of the multi-channel fiber grating demodulator (1) is connected to the communication transmission module (3); the output end of the communication transmission module (3) is connected to the input end of the computer calculation module (4); and the output end of the computer calculation module (4) is connected to the image drawing and display module (5). The optical signal emitted from the optical port of the multi-channel fiber grating demodulator (1) is incident into each fiber core of the multi-core fiber grating array (2) and transmitted along the optical fiber. The fiber gratings reflect the optical signal in sequence and enter the multi-channel fiber grating demodulator (1). The multi-channel fiber grating demodulator (1) communicates with the communication transmission module (3) to obtain the optical signal in real time. Figure 3 The strain difference experienced by each fiber grating in the multi-core fiber grating array (2) described in step one; the strain data of each fiber grating obtained are entered into the computer calculation module (4) through electrical connection, based on Figure 3 The relationship model between the curvature, bending direction, and joint bending angle of the three-core fiber grating array established in step two is used for the above-mentioned... Figure 3 Step three involves calculating the angles of each joint in the hand; finally, [the process is as follows]. Figure 3 In step four, hand shape reconstruction is performed to achieve accurate hand motion capture. The hand shape reconstruction results and hand motion capture results obtained by the computer calculation module (4) are displayed by the image drawing and display module (5).

[0076] The foregoing has shown and described the basic principles and main features of this utility model. Various changes and modifications may be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of this utility model as claimed.

Claims

1. A hand motion capture device and system based on multi-core fiber optic grating array sensing, characterized in that... include: Multi-channel fiber Bragg grating demodulator, multi-core fiber Bragg grating array, communication transmission module, computer processing module, image rendering and display module, and flexible glove; The multi-channel fiber Bragg grating demodulator is used to measure the wavelength change of each fiber Bragg grating in a multi-core fiber Bragg grating array in real time. The multi-core fiber Bragg grating array is composed of multiple fiber Bragg grating arrays arranged longitudinally and then bonded together. The fiber Bragg grating array is fabricated using an integrated in-line writing method. Each fiber Bragg grating array contains multiple fiber Bragg gratings distributed along the fiber axis, and the spacing between the fiber Bragg gratings corresponds to the sensing points of each joint, with a positional difference not exceeding ±1 mm. In the multi-core fiber Bragg grating array, multiple fiber Bragg gratings of different cores at the same position form a group, and the positional difference of the fiber Bragg gratings in different cores in each group does not exceed ±1 mm. The multi-core fiber Bragg grating array is deployed on a flexible glove; The aforementioned flexible glove is a wearable flexible glove with elasticity; The communication transmission module is used for real-time communication with the multi-channel fiber Bragg grating demodulator; The multi-channel fiber Bragg grating demodulator communicates with the communication transmission module and has real-time testing and data acquisition functions, which are used to obtain the strain of each fiber Bragg grating in the multi-core fiber Bragg grating array in real time. The computer calculation module has data analysis and processing functions. Based on the strain of each fiber grating in the multi-core fiber grating array deployed on the flexible glove, the bending angle and bending direction of each joint of the hand are obtained by calculating the curvature and bending direction of the multi-core fiber grating array, thereby realizing the capture of hand movements. The image drawing and display module has a real-time drawing and display function for hand movements, which is used to display the hand shape reconstruction results and hand movement capture results, and dynamically display hand movements.

2. The hand motion capture device and system based on multi-core fiber optic grating array sensing according to claim 1, characterized in that: The multi-core fiber Bragg grating array can be single or multiple, and the number of fiber Bragg grating groups in each multi-core fiber Bragg grating array can be adjusted. The multi-core fiber Bragg grating array is arranged on the side of the finger to outline the finger contour. The fiber Bragg grating groups located on the side of the finger are used to sense the bending angle of each finger joint. The fiber Bragg grating groups between the fingers are arranged in a U-shape to sense the opening and closing angle between the fingers. The fiber Bragg grating groups located at the metacarpophalangeal joints of each finger on the back of the hand are used to sense the bending and extension angles of the palm.

3. The hand motion capture device and system based on multi-core fiber optic grating array sensing according to claim 1, characterized in that: The multi-core fiber grating array consists of N+1 fiber gratings, with a central core and N other cores evenly distributed around it.

4. The hand motion capture device and system based on multi-core fiber optic grating array sensing according to claim 1, characterized in that: The multi-core fiber grating array uses 19 fiber grating groups; the multi-core fiber grating array has 3 fibers, with the three fibers arranged in a triangle and 120° apart from each other. The first multi-core fiber Bragg grating array comprises eight fiber Bragg gratings, starting from the wrist on the thumb side and arranged along the outer edge of the thumb. The first fiber Bragg grating is arranged longitudinally at the thumb's carpal joint and continues along the outer edge of the thumb. The second fiber Bragg grating is located longitudinally at the thumb's second metacarpophalangeal joint. The third fiber Bragg grating is located longitudinally at the thumb's interphalangeal joint. The multi-core fiber Bragg grating array continues along the outer edge of the thumb to the web between the thumb and index finger. The fourth fiber Bragg grating is arranged transversely, located 0.2 to 1.5 cm below the web between the thumb and index finger on the back of the hand. At a distance of cm, the multi-core fiber grating array is arranged in a U-shape upwards. The fifth group of fiber gratings is located longitudinally at the metacarpophalangeal joint of the index finger on the back of the hand, and continues to be arranged along the outer edge of the left side of the index finger. The sixth group of fiber gratings is located longitudinally at the proximal interphalangeal joint of the outer edge of the left side of the index finger. The seventh group of fiber gratings is located longitudinally at the distal interphalangeal joint of the outer edge of the left side of the index finger. The multi-core fiber grating array bypasses the fingertip of the index finger and continues to be arranged along the outer edge of the right side of the index finger to the base. On the back of the hand, it continues to be arranged in a U-shape to the left to the base of the left side of the middle finger. The eighth group of fiber gratings is located laterally between the index and middle fingers, 0.2~1.5 cm from the base. The second multi-core fiber Bragg grating array contains 7 fiber Bragg gratings, arranged from the wrist on the back of the hand towards the middle finger, reaching the metacarpophalangeal joint of the middle finger. The 9th fiber Bragg grating is arranged longitudinally, then continues upward along the left outer edge of the middle finger. The 10th fiber Bragg grating is arranged longitudinally at the proximal interphalangeal joint of the middle finger. The 11th fiber Bragg grating is located longitudinally at the distal interphalangeal joint of the middle finger, continuing along the outer edge of the middle finger, past the fingertip, and along the right outer edge of the middle finger to the base of the middle finger. It continues to the left in a U-shape on the back of the hand to the left base of the ring finger. The 12th fiber Bragg grating is located laterally between the middle and ring fingers. The first fiber grating is positioned between the fingers, 0.2-1.5 cm from the base. The multi-core fiber grating array continues upwards, along the left outer edge of the ring finger. The 13th fiber grating is longitudinally positioned at the proximal interphalangeal joint of the ring finger. The 14th fiber grating is longitudinally positioned at the distal interphalangeal joint of the ring finger, continuing along the outer edge of the ring finger, past the fingertip, and along the right outer edge of the ring finger to the base of the ring finger. On the back of the hand, it continues to be arranged in a U-shape to the left to the base of the left side of the ring finger. The 15th fiber grating is horizontally positioned between the ring finger and the little finger, 0.2-1.5 cm from the base. The third multi-core fiber Bragg grating array contains four fiber Bragg gratings, arranged from the back of the hand and wrist towards the little finger, up to the metacarpophalangeal joint of the little finger. The 16th fiber Bragg grating is arranged longitudinally, then moves to the upper left, gradually transitioning to the left outer side of the little finger. Along the left outer edge of the little finger, the 17th fiber Bragg grating is arranged longitudinally at the proximal interphalangeal joint of the little finger. The 18th fiber Bragg grating is located longitudinally at the distal interphalangeal joint of the little finger, continuing to be arranged along the outer edge of the little finger, past the tip of the little finger, and along the right outer side of the little finger, to the base of the little finger between the little finger and the ring finger, gradually transitioning to the right side to the metacarpophalangeal joint of the ring finger. The fiber Bragg gratings are arranged longitudinally and fit tightly against the hand.

5. A hand motion capture device and system based on multi-core fiber optic grating array sensing according to claim 1, characterized in that: The optical ports of the multi-channel fiber Bragg grating demodulator are respectively connected to the fiber cores of the I, II, and III multi-core fiber Bragg grating arrays; the electrical ports of the multi-channel fiber Bragg grating demodulator are connected to the communication transmission module; the output of the communication transmission module is connected to the input of the computer processing module; and the output of the computer processing module is connected to the image rendering and display module.

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