Bending sensor and bionic manipulator

Abstract

This application discloses a bending sensor and biomimetic manipulator. The sensor includes a light-emitting element, a light-guiding module, a light-mixing module, and a light-sensing module. The light-emitting element is located at one end of the light-guiding module, and the light-mixing module and the light-sensing module are arranged in sequence at the other end of the light-guiding module. The light-emitting element is used to emit a first light source, a second light source, and a third light source. The light-guiding module includes a first fiber core layer, a second fiber core layer, a third fiber core layer, and an outer cladding layer. The first fiber core layer, the second fiber core layer, and the third fiber core layer are respectively used to transmit the first light source, the second light source, and the third light source, thereby obtaining three types of transmitted light. The outer cladding layer surrounds the first fiber core layer, the second fiber core layer, and the third fiber core layer. The light-mixing module is used to mix the three types of transmitted light to obtain mixed light. The light-sensing module is used to determine the bending angle and direction of the light-guiding module based on the attenuation of the light intensity of the three light sources in the mixed light. The sensor can perform omnidirectional bending measurement, which can ensure the flexibility of the biomimetic manipulator integrated with the sensor.

Description

Technical Field

[0001] The present application relates to the field of sensor technology, and in particular to a bending sensor and a bionic manipulator. Background Art

[0002] The human hand is a remarkable achievement of human evolution, renowned for its complex morphological features. These features are evident in its precise skeletal structure, diverse joint configurations, and tightly coordinated control systems of nerves and muscles. Consequently, the human hand possesses numerous degrees of freedom and a high degree of dexterity, enabling it to perform delicate manipulation tasks such as medical surgery, industrial assembly, and complex servicing. Furthermore, proprioceptors that sense hand posture, including muscle spindles, Golgi tendon organs, and Pacinian corpuscles, are embedded in the tendons and muscles of the human hand. Under the coordinated control of these sensors and nerves, human fingers can move with remarkable precision.

[0003] To achieve near-human-level dexterity in robotic end-effectors, numerous anthropomorphic robotic hand configurations have been developed. For example, the bionic dexterous hand developed by Intime Robotics features six micro-linear actuators, two of which control the two degrees of freedom of the thumb's joints, while the remaining four actuators drive the movements of the remaining four fingers. While linkage mechanisms enable some movement coordination, its motion modes are still limited to basic grasping patterns, such as making a fist and extending a palm. Another representative example is the IH2 Azzurra dexterous hand, which utilizes a five-degree-of-freedom tendon transmission structure, with each finger actuated by an independent tendon. The Shadow dexterous hand, on the other hand, utilizes 20 DC servo motors to achieve fully independent control of each finger joint's degrees of freedom, enabling it to perform complex hand manipulations. The Hanns dexterous hand integrates a single motor in the palm, combined with a tendon transmission pathway to create an underactuated system that can simulate human grasping and pinching movements. It is worth noting that while existing robotic hands can perform basic manipulation tasks, they generally lack the flexion and extension of the metacarpophalangeal joints, which are characteristic of human fingers. This makes them difficult to perform delicate tasks such as playing the piano, tying shoes, and writing.

[0004] Current humanoid dexterous hands generally lack the multi-degree-of-freedom proprioception capabilities similar to those of the human hand, particularly in the coordinated control of adduction / abduction. While the combination of flexible actuators and sensors shows promise, existing sensing solutions remain limited: while optical sensors can detect overall bending through changes in light intensity, they cannot discern bending direction. Resistive sensors are effective at monitoring single-degree-of-freedom bending through changes in resistance, but in solutions like liquid metal strain sensing, multi-degree-of-freedom complex motions still produce posture coupling. In summary, current technology is primarily limited to single-joint degree-of-freedom measurement and has yet to achieve decoupled sensing of coordinated flexion and adduction / abduction motion. Therefore, despite existing research involving adduction / abduction drive mechanisms, humanoid dexterous hand systems with a complete five-finger structure and combined abduction / adduction functionality remain rare within the current technological landscape. Summary of the Invention

[0005] The main technical problem solved by this application is to provide a bending sensor and a bionic manipulator to solve the problem that existing humanoid dexterous hands are limited to single-degree-of-freedom measurement of dexterous finger joints and are difficult to decouple the coordinated movements involving finger flexion and adduction / abduction.

[0006] To solve the above technical problems, a technical solution adopted in the present application is to provide a bending sensor, including a light-emitting component, a light-guiding module, a light-mixing module and a light-sensing module, wherein the light-emitting component is located at one end of the light-guiding module, and the light-mixing module and the light-sensing module are arranged in sequence at the other end of the light-guiding module; the light-emitting component is used to simultaneously emit a first light source, a second light source and a third light source; the light-guiding module includes a first fiber core layer, a second fiber core layer, a third fiber core layer and an outer cladding layer, wherein the first fiber core layer, the second fiber core layer and the third fiber core layer are parallel to each other, and the first fiber core layer, the second fiber core layer and the third fiber core layer are used to conduct the first light source, the second light source and the third light source respectively, and obtain three colors of conducted light correspondingly; the outer cladding layer is wrapped around the periphery of the first fiber core layer, the second fiber core layer and the third fiber core layer; the light-mixing module is used to mix the three colors of conducted light to obtain mixed light; the light-sensing module is used to judge the bending angle and direction of the light-guiding module according to the attenuation of the light intensity of the three light sources in the mixed light.

[0007] The present application also provides a bionic robotic arm, comprising a palm and a plurality of fingers connected to the palm, wherein the palm and the fingers are provided with the above-mentioned bending sensors for detecting the posture angles of the fingers.

[0008] The beneficial effects of the present application are as follows: the present application discloses a bending sensor and a bionic manipulator, the bending sensor including a light-emitting component, a light-guiding module, a light-mixing module and a light-sensing module, the light-emitting component is located at one end of the light-guiding module, and the light-mixing module and the light-sensing module are arranged in sequence at the other end of the light-guiding module; the light-emitting component is used to simultaneously emit a first light source, a second light source and a third light source; the light-guiding module includes a first fiber core layer, a second fiber core layer, a third fiber core layer and an outer cladding layer, the first fiber core layer, the second fiber core layer and the third fiber core layer are parallel to each other, the first fiber core layer, the second fiber core layer and the third fiber core layer are respectively used to conduct the first light source, the second light source and the third light source, and correspondingly obtain three colors of conducted light; the outer cladding layer wraps around the outer periphery of the first fiber core layer, the second fiber core layer and the third fiber core layer; the light-mixing module is used to mix the three colors of conducted light to obtain mixed light; the light-sensing module is used to judge the bending angle and direction of the light-guiding module according to the attenuation of the light intensity of the three light sources in the mixed light. The bending sensor exhibits good measurement performance, stability and repeatability in multiple degrees of freedom, and its sensing capability effectively meets the posture perception requirements of bionic manipulators performing multi-degree-of-freedom manipulation tasks. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of the overall structure of an embodiment of a bending sensor according to the present application;

[0010] Figure 2 This is a principle diagram of an optical path in a non-bending state according to an embodiment of a bending sensor of the present application;

[0011] Figure 3 This is a principle diagram of an optical path in a bent state according to an embodiment of a bending sensor of the present application;

[0012] Figure 4 The following are graphs showing the intensity attenuation of red light, green light, and blue light and their corresponding trend under different strains of the core layer of a bending sensor with 2, 3, 6, and 9 short optical fiber segments, respectively;

[0013] Figure 5 This is a schematic diagram of a spatial rectangular coordinate system established with one end of the bending sensor as the origin in an embodiment of the bending sensor according to the present application;

[0014] Figure 6 is a cross-sectional schematic diagram of a light-emitting element in an embodiment of a bending sensor according to the present application;

[0015] Figure 7 This is a structural diagram of an embodiment of a bionic manipulator according to the present application;

[0016] Figure 8 This is a schematic diagram of the specific structure of an embodiment of a bionic manipulator according to the present application;

[0017] Figure 9 This is a schematic diagram of the specific structure of the fingers in an embodiment of a bionic manipulator according to the present application;

[0018] Figure 10 This is a working principle diagram of an embodiment of a bionic manipulator according to the present application;

[0019] Figure 11 This is a graph of light intensity attenuation changes collected during 100 cycles of reciprocating stretching at a strain of 10% in an embodiment of a bending sensor according to the present application;

[0020] Figure 12 This is a schematic diagram showing the change of light intensity attenuation over time at different strain levels according to an embodiment of a bending sensor of the present application;

[0021] Figure 13 This is a schematic diagram of light intensity attenuation changes under different radial pressures according to an embodiment of a bending sensor of the present application;

[0022] Figure 14 This is a schematic diagram of light intensity attenuation changes at different strain levels according to an embodiment of a bending sensor of the present application;

[0023] Figure 15 This is a schematic diagram of the relationship between the strain of short optical fiber segments of three core layers and the pitch angle during the pitching process according to an embodiment of a bending sensor of the present application;

[0024] Figure 16 This is a schematic diagram showing the relationship between the strain of short optical fiber segments of three core layers and the yaw angle during yaw bending according to an embodiment of a bending sensor of the present application;

[0025] Figure 17 This is a schematic diagram showing the effect of short optical fiber segments of three core layers on light intensity attenuation during a pitching process according to an embodiment of a bending sensor of the present application;

[0026] Figure 18 This is a schematic diagram showing the effect of short optical fiber segments of three core layers on light intensity attenuation during yaw bending according to an embodiment of a bending sensor of the present application;

[0027] Figure 19 This is a schematic diagram showing the comparison between the actual pitch angle calculated and the theoretical pitch angle according to an embodiment of a bending sensor of the present application;

[0028] Figure 20 This is a schematic diagram showing the comparison between the actual yaw angle calculated and the theoretical yaw angle according to an embodiment of a bending sensor of the present application;

[0029] Figure 21A schematic diagram showing the change over time of the bending angle of the index finger and the intensity attenuation of light conducted by three fiber core layers in a corresponding bending sensor during the use of scissors in an embodiment of a bionic manipulator according to the present application, and a corresponding color coordinate diagram;

[0030] Figure 22 A schematic diagram showing the change over time of the bending angle of the index finger and the intensity attenuation of light conducted by three fiber core layers in a corresponding bending sensor during operation of a mouse according to an embodiment of a bionic manipulator of the present application, and a corresponding color coordinate diagram;

[0031] Figure 23 This is a color coordinate diagram corresponding to the index finger, middle finger, ring finger and little finger during the process of playing the piano in one embodiment of a bionic manipulator according to the present application, as well as a schematic diagram of the change over time of the bending angle of each finger and the light intensity attenuation of the light transmitted by the three fiber core layers in the corresponding bending sensor. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0033] It should be noted that when an element is referred to as being “fixed on” or “set on” another component, it can be directly on the other component or indirectly set on the other component; when a component is referred to as being “connected to” another component, it can be directly connected to the other component or indirectly connected to the other component.

[0034] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this application.

[0035] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Thus, features specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" and "several" mean two or more, unless otherwise specifically defined.

[0036] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions under which this application can be implemented. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the efficacy and purpose that can be achieved by this application.

[0037] Figure 1 An embodiment of a bending sensor of the present application is shown, which includes a light-emitting element 1, a light-guiding module 2, a light-mixing module 3 and a light-sensing module 4. The light-emitting element 1 is located at one end of the light-guiding module 2, and the light-mixing module 3 and the light-sensing module 4 are arranged in sequence at the other end of the light-guiding module 2.

[0038] Combine Figure 2 The light-emitting component 1 is used to simultaneously emit the first light source, the second light source and the third light source; the light-guiding module 2 includes a first fiber core layer 21, a second fiber core layer 22, a third fiber core layer 23 and an outer cladding layer 24. The first fiber core layer 21, the second fiber core layer 22 and the third fiber core layer 23 are parallel to each other. The first fiber core layer 21, the second fiber core layer 22 and the third fiber core layer 23 are respectively used to conduct the first light source, the second light source and the third light source, and correspondingly obtain three colors of conducted light; the outer cladding layer 24 is wrapped around the outer periphery of the first fiber core layer 21, the second fiber core layer 22 and the third fiber core layer 23; the light-mixing module 3 is used to mix the three colors of conducted light to obtain mixed light; the photosensitive module 4 is used to judge the bending angle and direction of the light-guiding module 2 according to the attenuation of the light intensity of the three light sources in the mixed light.

[0039] Combine Figure 2 and Figure 3 The light-emitting element 1 uses a three-color LED that can simultaneously emit a first light source, a second light source, and a third light source. These three colors of light are respectively input into the first fiber core layer 21, the second fiber core layer 22, and the third fiber core layer 23 for transmission, thereby producing three colors of transmitted light. Furthermore, the light mixing module 3 mixes the three colors of transmitted light to produce mixed light. The light sensing module 4 determines the bending angle and direction of the light guide module 2 based on the attenuation of the light intensity of the three colors of light in the mixed light.

[0040] In this embodiment, the first light source is red light, and the corresponding wavelength range is distributed between 610nm and 620nm; the second light source is green light, and the corresponding wavelength range is distributed between 520nm and 535nm; the third light source is blue light, and the corresponding wavelength range is distributed between 465nm and 480nm.

[0041] In some other embodiments, light sources of other colors may also be used, such as yellow light, purple light, etc.; as long as the colors of the first light source, the second light source and the third light source are different, the corresponding wavelengths are distributed within the wavelength range of the corresponding colors of light.

[0042] like Figure 1 and Figure 2 As shown, the first fiber core layer 21 , the second fiber core layer 22 and the third fiber core layer 23 each include a plurality of short optical fiber segments 20 that are arranged side by side and have the same size and the same spacing distance.

[0043] like Figure 1 As shown, the light guide module 2 is a horizontally placed cylinder. The length L of the light guide module obtained at this time is 150 mm, and the cross-sectional diameter is The first core layer 21, the second core layer 22 and the third core layer 23 have the same size, wherein the length L is 150 mm and the cross-sectional diameter is The short fiber segments 20 in different core layers have the same size, where the length l is 4 mm and the cross-sectional diameter is and within one core layer, the spacing distance d between two adjacent short optical fiber segments 20 is 0.5 mm.

[0044] In some other embodiments, generally, the length L of the obtained light guide module 2 is between 50 mm and 200 mm, and the cross-sectional diameter is The length L of the first core layer 21, the second core layer 22 and the third core layer 23 is between 50mm-200mm, and the cross-sectional diameter is between 5mm-20mm; The length l of the short optical fiber segment 20 in different core layers is between 2mm-7mm, and the cross-sectional diameter is between 1.5-6mm; The diameter of the short optical fiber segments 20 is between 1.5 mm and 6 mm, and the spacing d between two adjacent short optical fiber segments 20 in one core layer is between 0.3 mm and 0.7 mm. Other sizes are also possible, as long as the sizes of the various parts of the bending sensor meet the actual use requirements.

[0045] It should be noted that the first core layer 21, the second core layer 22, and the third core layer 23 all use PMMA optical fiber. PMMA optical fiber has the characteristics of high refractive index and low optical loss, resulting in negligible attenuation of light intensity during short-distance propagation. Therefore, the sensor experiences insignificant optical bending loss, resulting in reduced sensitivity of the sensor. In addition, when the sensor is bent, the mismatch in elastic modulus between the PMMA optical fiber and the elastic outer cladding 24 easily leads to stress concentration within the PMMA optical fiber, increasing the possibility of microcrack formation or fiber breakage. In order to alleviate these challenges, the present application divides the PMMA optical fiber into several short optical fiber segments 20 to fill the outer cladding 24 of the sensor, thereby significantly improving the macroscopic bending loss rate of the PMMA optical fiber and alleviating internal residual stress.

[0046] like Figure 4 The figure shows the correlation between the number of short fiber segments 20 in the bend sensor and the light intensity attenuation under different stretching conditions. Under different stretching conditions, the changing trends of the light intensity attenuation of red light, green light, and blue light are compared when the strain of the corresponding core layer gradually increases in the core layers with 2, 3, 6, and 9 short fiber segments 20. Among them, the R channel attenuation represents the light intensity attenuation of red light in the first core layer 21, the G channel attenuation represents the light intensity attenuation of green light in the second core layer 22, and the B channel attenuation represents the light intensity attenuation of blue light in the third core layer 23. It can be seen that increasing the number of short fiber segments 20 in each core layer of the bend sensor leads to a decrease in light intensity attenuation. At the same time, in the bend sensor with 6 short fiber segments 20, the light intensity attenuation of red light, green light, and blue light is more uniform.

[0047] In some embodiments, the first fiber core layer 21 , the second fiber core layer 22 , and the third fiber core layer 23 each include six short fiber segments 20 , which can enhance the uniformity of the measurement factors (GF) of the red light, green light, and blue light intensities and prevent an excessive number of short fiber segments 20 from causing a reduction in light intensity attenuation.

[0048] like Figure 2 As shown, when the light guide module 2 is in an unbent state, the three colors of light emitted by the light emitting element 1 are input from one end of the first core layer 21, the second core layer 22, and the third core layer 23, respectively. They are then transmitted through the first core layer 21, the second core layer 22, and the third core layer 23 by total internal reflection, resulting in three colors of conducted light. The three colors of conducted light are then output from the other ends of the first core layer 21, the second core layer 22, and the third core layer 23, respectively. The three colors of conducted light are then mixed by the mixing module 3 to produce mixed light. Finally, the photosensitive module 4 can determine the intensity of the three different wavelengths of light within the spectrum based on the mixed light.

[0049] It should be noted that the attenuation of light in a medium can be expressed as:

[0050] ;

[0051] in, and Represent the input and output light intensities respectively; e represents the natural logarithm; and represent the absorption coefficient and optical path of the medium respectively. Therefore, the intensity of the light emitted from the end of the light guide module 2 (the end close to the light mixing module 2) can be expressed as the first formula:

[0052] ;

[0053] Wherein, n is the total number of short optical fiber segments 20 included in the bend sensor; Indicates the absorption coefficient of PMMA optical fiber; represents the absorption coefficient of air between two adjacent short fiber segments 20 in the same fiber core layer; l represents the length of each short fiber segment 20; and d represents the spacing between two adjacent short fiber segments 20. The corresponding light intensity attenuation can be expressed as the second formula:

[0054] .

[0055] Furthermore, the first formula Substitute into the second formula , the relationship between the light intensity attenuation and the length of the short optical fiber segment, as well as the spacing between two adjacent short optical fiber segments 20 in the same fiber core layer can be obtained as follows:

[0056] .

[0057] Combine Figure 3 When the bending sensor bends, the first fiber core layer 21 guiding the red light is subjected to tensile stress. This stress causes the spacing between two adjacent short fiber segments 20 of the first fiber core layer 21 to increase. , which results in an increase in light intensity attenuation. On the other hand, the third core layer 23 guiding blue light is located on the inner side of the sensor and experiences compressive stress, which results in a decrease in the spacing distance between two adjacent short optical fiber segments 20 of the third core layer 23. As a result, the optical path length within each core layer is altered, causing the intensity of the composite spectrum of each unique wavelength of light to vary.

[0058] like Figure 5 As shown, in order to determine the bending angle and direction of the bending sensor by the change of light intensity attenuation, the present application establishes a spatial rectangular coordinate system {O} for the bending sensor. The pitch angle and yaw angle shown in the figure represent the bending angle of the corresponding direction of the bending sensor, where Indicates the angular range of the pitch angle; The yaw angle range is shown in Figure 2. Based on the pitch and yaw angles, the accurate bending angle and bending direction of the bending sensor can be obtained.

[0059] It should be noted that, assuming that one end of the bend sensor remains fixed and the other end can be bent in any direction, the strain generated by the short optical fiber segment 20 at its respective cross-sectional position is proportional to the distance from the center point of the short optical fiber segment 20 to the neutral axis. That is, the strain of the short optical fiber segment 20 can be expressed as:

[0060] ;

[0061] in, represents the extension of the short optical fiber segment 20; L represents the original length of the short optical fiber segment 20.

[0062] like Figure 6 As shown, the first light source, the second light source and the third light source are arranged on the circumference. They are arranged at intervals to form an equilateral triangle layout. Correspondingly, the first core layer 21, the second core layer 22 and the third core layer 23 are also arranged in an equilateral triangle layout on the corresponding cross section. Wherein, R0 represents the center point of the first light source / corresponding short fiber segment 20, G0 represents the center point of the second light source / corresponding short fiber segment 20, and B0 represents the center point of the third light source / corresponding short fiber segment 20; s represents the distance from the center point of the first light source / second light source / third light source to the center of the cross section O, that is, the distance from the center point of each short fiber segment 20 on the cross section to the neutral axis; point R d , G d and B d Represent the projection points of points R0, G0 and B0 onto the curved plane respectively.

[0063] Furthermore, when the bending sensor is bent along the bending plane, the strain of each short optical fiber segment 20 in the first core layer 21, the second core layer 22, and the third core layer 23 can be expressed as:

[0064]

[0065] in, represents the strain of the short fiber segment of the first core layer 21; represents the strain of the short fiber segment of the second core layer 22; represents the strain of the short optical fiber segment of the third core layer 23; 、 and represent the original lengths of the short optical fiber segments 20 in the first core layer 21, the second core layer 22, and the third core layer 23, respectively; 、 and They respectively represent the extension of the short optical fiber segments in the first core layer 21, the second core layer 22 and the third core layer 23; r represents the bending radius of the bending sensor; s represents the distance from the center point of each short optical fiber segment 20 on the cross section to the neutral axis; θ represents the angle between the cross section of each short optical fiber segment 20 and the bending plane.

[0066] In this embodiment, .

[0067] Furthermore, the light mixing module 3 uses a light mixing board, and the photosensitive module 4 is a PCB board. A chromaticity detection chip 40 is provided on the PCB board, and the chromaticity detection chip 40 uses the chip TCS3472 to measure the light intensity attenuation of each color of light to calculate the bending angle and bending direction of the bending sensor.

[0068] Furthermore, the strain and light intensity mapping relationship of the short optical fiber segment 20 of the first core layer 21, the second core layer 22 and the third core layer 23 can be expressed as:

[0069] ;

[0070] in, 、 and Respectively represent the calibration coefficients of the first core layer 21, the second core layer 22 and the third core layer 23; 、 and Respectively represent the light intensity attenuation of the three light sources transmitted through the first core layer 21, the second core layer 22 and the third core layer 23; 、 and They represent the compensation coefficients of the first core layer 21, the second core layer 22 and the third core layer 23 respectively.

[0071] Furthermore, in the photosensitive module 4, the bending angle and direction of the bending sensor are obtained according to the calculation formulas of the pitch angle and the yaw angle; wherein the calculation formulas of the pitch angle and the yaw angle are respectively:

[0072]

[0073] Wherein, P represents the pitch angle of the bending sensor; Y represents the yaw angle of the bending sensor.

[0074] like Figure 11The figure shows the intensity attenuation data for three light sources collected during 100 cycles of reciprocating stretching at a strain of 10%. A detailed view of the intensity attenuation of the three light sources during the initial and final three cycles is provided. The red curve represents the intensity attenuation of red light; the green curve represents the intensity attenuation of green light; and the blue curve represents the intensity attenuation of blue light. The calculated root mean square errors (RMSEs) for the three light source channels during the initial three cycles and the final three cycles were 2.1% (R channel), 1.9% (G channel), and 3.2% (B channel), respectively. These results demonstrate the high repeatability and performance consistency of the proposed bending sensor.

[0075] like Figure 12 As shown in Figure 1, the step response evaluations for strains of 0.25%, 0.5%, 1%, 2.5%, 5%, and 10% are shown. The bending sensor can detect strains up to 2.5%, indicating that it has a strong tensile response.

[0076] like Figure 13 The figure shows the sensitivity of the bend sensor proposed in this application to radial compression. During the bending process of the bend sensor, a standard force sensor was used to apply radial pressure ranging from 0N to 50N. It can be seen that the bend sensor can maintain a stable output response when the radial pressure is less than 10N.

[0077] like Figure 14 As shown in Figures (i) to (vi), the hysteresis response characteristics of the bending sensor proposed in this application at different strain levels are illustrated. When the strain is 0.25%, 0.5%, 1%, 2.5%, 5% and 10%, the corresponding hysteresis coefficients are detailed in Table 1.

[0078] Table 1. Hysteresis coefficients of each fiber core layer in the bending sensor under different strain conditions

[0079] strain(%) R channel (%) G channel (%) B channel (%) 0.25% 11.95% 6.27% 7.09% 0.5% 9.30% 7.91% 2.97% 1% 3.85% 4.68% 5.51% 2.5% 3.41% 3.53% 3.28% 5% 2.57% 5.76% 4.57% 10% 7.73% 3.36% 4.41%

[0080] like Figure 15 and Figure 16The figures show the relationship between the strain of the short fiber segments of the three core layers and the theoretical pitch and yaw angles during pitch and yaw bending, respectively. ANSYS software was used to measure the strain of the short fiber segments of the three core layers within the bend sensor under ±90° pitch and ±90° yaw. The corresponding theoretical pitch and yaw angles were then calculated based on the strain data. It can be seen that during pitch, the short fiber segments of the second core layer (G channel) and the third core layer (B channel) exhibit equal strain, while the short fiber segment of the first core layer (R channel) exhibits slightly higher strain. In contrast, during yaw bending, the short fiber segments of the second core layer (G channel) and the third core layer (B channel) exhibit equivalent strain, which is higher than the strain of the short fiber segment of the first core layer (R channel).

[0081] like Figure 17 and Figure 18 The figures show the effect of the short fiber segments in the three core layers on light intensity attenuation during pitch and yaw bending, respectively. During pitch, the attenuation rate of the short fiber segments in the first core layer (R channel) is slightly higher than that of the short fiber segments in the second core layer (G channel) and the third core layer (B channel). During yaw bending, the attenuation of the short fiber segments in the first core layer (R channel) is lower than that of the short fiber segments in the second core layer (G channel) and the third core layer (B channel). The short fiber segments in the second core layer (G channel) and the third core layer (B channel) exhibit consistent attenuation trends. It can be seen that the light intensity attenuation trend is consistent with the strain pattern determined in the simulation results, thus confirming the feasibility of calculating finger posture based on light intensity attenuation.

[0082] like Figure 19 and Figure 20 The figure shows the results of using the theoretical pitch and yaw angles of the inertial measurement unit (IMU) as reference attitude parameters and comparing them with the calculated pitch and yaw angles calculated by the bend sensor. The average measurement error of the bend sensor for pitch is ±2.13°, and the average measurement error for yaw is ±2.34°. These results show that the bend sensor has good measurement capabilities and is suitable for tasks that require sensing multi-degree-of-freedom finger postures.

[0083] Based on the unified inventive concept, such as Figure 7 As shown, the present application also provides a bionic robotic hand, including a palm 10, a plurality of fingers 20 connected to the palm 10, and bending sensors as described above are provided in the palm 10 and the fingers 20 for detecting the posture angle of the fingers 20.

[0084] Among them, L DIP Indicates the distal phalanx of the little finger, L PIP Indicates the proximal phalanx of the little finger, L MCP Indicates the metacarpophalangeal joint of the little finger, LABD R represents the joint freedom of the little finger adduction / abduction movement; DIP Represents the distal phalanx of the ring finger, R PIP Represents the proximal phalanx of the ring finger, R MCP Represents the metacarpophalangeal joint of the ring finger, R ABD M represents the joint freedom of the ring finger adduction / abduction movement; DIP Indicates the distal phalanx of the middle finger, M PIP Indicates the proximal phalanx of the middle finger, M MCP Indicates the metacarpophalangeal joint of the middle finger, M ABD Represents the joint freedom of the middle finger adduction / abduction movement; I DIP Indicates the distal phalanx joint of the index finger, I PIP Indicates the proximal phalanx joint of the index finger, I MCP Indicates the metacarpophalangeal joint of the index finger, I ABD T represents the joint freedom of the index finger adduction / abduction movement; IP T represents the thumb joint of the thumb. MCP Indicates the metacarpophalangeal joint of the thumb, I ROT Represents the joint degrees of freedom for thumb adduction / abduction motion.

[0085] like Figure 8 and Figure 9 As shown, the light emitting element 1 is arranged between the fingertip 201 and the distal knuckle 202 of the finger 20 , the light guide module 2 is integrated in the distal knuckle 202 and the proximal knuckle 203 of the finger 20 , and the light mixing module 3 and the light sensing module 4 are fixed on the palm 10 .

[0086] The palm 10 is manufactured using 3D printing technology, as are the fingertips 201, distal knuckles 202, proximal knuckles 203, distal knuckle joints 204, proximal knuckle joints 205, and metacarpophalangeal joints 206 of the fingers 20. Furthermore, a bend sensor's light guide module 2 can be integrated into the distal knuckles 202 and proximal knuckles 203 using a one-shot molding process, while the corresponding three-color LED is embedded in the fingertips 201. Simultaneously, the corresponding light mixing board and colorimetry detection chip 40 are mounted on the palm 10.

[0087] In this embodiment, each finger 20 is designed from a combination of rigid and flexible materials to ensure joint mobility and flexibility. With the exception of the thumb, which has two degrees of freedom, each of the other four fingers 20 has four degrees of freedom. This structure enables each finger 20 to independently flex, abduct, and adduct, facilitating the execution of complex and delicate movements.

[0088] Furthermore, in order to enable the finger 20 to flex, abduct and adduct, the movement of the finger 20 is controlled by a tendon drive mechanism.

[0089] like Figure 8 As shown, based on the tendon driving principle of the human hand, nine servo motors 5 are installed on the arm of the bionic manipulator to achieve flexion, adduction and abduction of the fingers 20 through tendon tension.

[0090] like Figure 9 As shown, flexor and extensor chordae tendineae 207 are anchored to fingertips 201 to facilitate flexion and extension of finger 20. Adduction and abduction chordae tendineae 208 are fixed to proximal phalanges 203 to control adduction and abduction of finger 20. Flexor and extensor chordae tendineae 207 and adduction and abduction chordae tendineae 208 are controlled by two servo motors, namely, flexion-extension servo motor 51 and adduction-abduction servo motor 52.

[0091] Combine Figure 10 As shown, due to a flawed drive design for finger 20, when the flexion-extension servo motor 51 drives the winding wheel, the inner flexor and extensor chordae tendineae 207 are tightened while the outer flexor and extensor chordae tendineae 207 are relaxed. Consequently, the distal phalanx 202 and proximal phalanx 203 can bend naturally, mimicking the movement of a human hand. Similarly, the adduction-abduction servo motor 52 drives the winding wheel to control the tension of the adduction-abduction chordae tendineae 208, achieving abduction and adduction of the metacarpophalangeal joint 206.

[0092] In this embodiment, each finger 20 is integrated with a omnidirectional bend sensor to detect the finger's posture angles, including the pitch angle (flexion) and the yaw angle (adduction-abduction). This design approach not only ensures the flexibility and compliance of the finger 20 but also provides two degrees of freedom for the metacarpophalangeal joint 206. Thus, each metacarpophalangeal joint 206 of the finger 20 has two degrees of freedom, enabling the finger 20 to independently perform adduction, abduction, and flexion movements, as well as complex coordinated movements.

[0093] like Figure 21 Figure 2 shows the bending angle of the index finger during the biomimetic manipulator's use of scissors and the corresponding time-varying attenuation of the light intensity transmitted by the three fiber core layers in the bending sensor. In this task, flexion control is achieved by bending the index finger. The target pitch angle is input into the control system, and the bending sensor provides real-time feedback on the finger posture during the bending process. This enables a closed-loop control strategy to accurately achieve the target angle. Due to the tension exerted by the tendons on the finger, the finger bending motion driven by the corresponding servo motor exhibits a certain degree of hysteresis. In addition, the sensor data from the index finger is intuitively represented by the color coordinates on the right side of the figure. It can be seen that during the bending process, the blue and green light attenuate significantly, causing the color coordinates to shift toward the red region.

[0094] like Figure 22 The figure shows the time-varying changes in the index finger's bending angle and the corresponding intensity attenuation of the light transmitted through the three core layers of the bend sensor during the biomimetic manipulator's mouse operation. The figure begins by bending the index finger and clicking the left mouse button. The index finger then moves inward and flexes, and the middle mouse button is clicked. The color coordinates on the right side of the figure clearly indicate the distinct trajectory changes of the biomimetic manipulator as the left and middle mouse buttons are clicked.

[0095] like Figure 23 As shown in the figure, the left side shows the color coordinates corresponding to the index finger, middle finger, ring finger, and little finger during the bionic robotic hand playing the piano, and the right side shows the bending angle of each finger and the change in the light intensity attenuation of the light transmitted by the three core layers in the corresponding bending sensor over time. Among them, the color coordinates of each finger visually represent the color data from the corresponding bending sensor. Each finger has a specific note on the piano, except for the little finger, which plays two notes in sequence through adduction and abduction movements. Because playing the piano requires a relatively small finger flexion amplitude, there is a strong correlation between the target angle input to the control system and the angle reported by the bending sensor.

[0096] It can be seen that the present application discloses a bending sensor and a bionic manipulator, including a light-emitting component, a light-guiding module, a light-mixing module and a photosensitive module, the light-emitting component is located at one end of the light-guiding module, and the light-mixing module and the photosensitive module are arranged in sequence at the other end of the light-guiding module; the light-emitting component is used to simultaneously emit a first light source, a second light source and a third light source; the light-guiding module includes a first fiber core layer, a second fiber core layer, a third fiber core layer and an outer cladding, the first fiber core layer, the second fiber core layer and the third fiber core layer are parallel to each other, the first fiber core layer, the second fiber core layer and the third fiber core layer are respectively used to conduct the first light source, the second light source and the third light source, and correspondingly obtain three colors of conducted light; the outer cladding wraps around the outer periphery of the first fiber core layer, the second fiber core layer and the third fiber core layer; the light-mixing module is used to mix the three colors of conducted light to obtain mixed light; the photosensitive module is used to judge the bending angle and direction of the light-guiding module according to the attenuation of the light intensity of the three light sources in the mixed light. The bending sensor exhibits good measurement performance, stability and repeatability in multiple degrees of freedom, and its sensing capability effectively meets the posture perception requirements of bionic manipulators performing multi-degree-of-freedom manipulation tasks.

[0097] The above are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structural transformations made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A bending sensor, characterized in that: It includes a light-emitting element, a light-guiding module, a light-mixing module and a light-sensing module, wherein the light-emitting element is located at one end of the light-guiding module, and the light-mixing module and the light-sensing module are sequentially arranged at the other end of the light-guiding module; The light emitting element is used to simultaneously emit the first light source, the second light source and the third light source; The light guide module includes a first fiber core layer, a second fiber core layer, a third fiber core layer and an outer cladding layer, wherein the first fiber core layer, the second fiber core layer and the third fiber core layer are parallel to each other, and the first fiber core layer, the second fiber core layer and the third fiber core layer are respectively used to conduct the first light source, the second light source and the third light source, and correspondingly obtain three colors of conducted light; the outer cladding layer is wrapped around the periphery of the first fiber core layer, the second fiber core layer and the third fiber core layer; The light mixing module is used to mix the three colors of conducted light to obtain mixed light; The photosensitive module is used to determine the bending angle and direction of the light guide module according to the light intensity attenuation of the three light sources in the mixed light; The first light source, the second light source and the third light source are arranged at intervals of 120° on the circumference to form an equilateral triangle layout; the first fiber core layer, the second fiber core layer and the third fiber core layer are also arranged in an equilateral triangle on the corresponding cross section.

2. The bending sensor according to claim 1, wherein The first fiber core layer, the second fiber core layer and the third fiber core layer each include a plurality of short optical fiber segments arranged side by side with the same size and the same spacing distance.

3. The bending sensor according to claim 2, wherein: When the bending sensor is bent along the bending plane, the strains of the short optical fiber segments of the first core layer, the second core layer, and the third core layer are respectively: ； in, representing the strain of the short optical fiber segment of the first core layer; represents the strain of the short optical fiber segment of the second core layer; Indicates the strain of the short optical fiber segment of the third core layer; 、 and represent the original lengths of the short optical fiber segments of the first core layer, the second core layer, and the third core layer, respectively; 、 and represents the extension of the short optical fiber segments of the first core layer, the second core layer and the third core layer respectively; r represents the bending radius of the bending sensor; s represents the distance from the center point of each short optical fiber segment on the cross section to the neutral axis; θ represents the angle between the cross section of each short optical fiber segment and the bending plane.

4. The bending sensor according to claim 3, characterized in that The strain and light intensity mapping relationship of the short optical fiber segments of the first core layer, the second core layer, and the third core layer is expressed as: ； in, 、 and Respectively represent the calibration coefficients of the first core layer, the second core layer and the third core layer; 、 and Respectively represent the attenuation of the light intensity of the three light sources transmitted through the first core layer, the second core layer, and the third core layer; 、 and represent the compensation coefficients of the first core layer, the second core layer and the third core layer respectively.

5. The bending sensor according to claim 4, characterized in that In the photosensitive module, the bending angle and direction of the bending sensor are obtained according to the calculation formula of the pitch angle and the yaw angle; The calculation formulas for the pitch angle and yaw angle are: ； Wherein, P represents the pitch angle of the bending sensor; Y represents the yaw angle of the bending sensor.

6. The bending sensor according to claim 1, wherein The first light source is red light with a wavelength between 610nm and 620nm, the second light source is green light with a wavelength between 520nm and 535nm, and the third light source is blue light with a wavelength between 465nm and 480nm.

7. The bending sensor according to claim 2, wherein: The light guide module has a length of 50 mm to 200 mm and a cross-sectional diameter of 5 mm to 20 mm; The first core layer, the second core layer and the third core layer have the same size, wherein the length is between 50 mm and 200 mm and the cross-sectional diameter is between 1.5 mm and 6 mm; The length of the short optical fiber segment is between 2 mm and 7 mm, the cross-sectional diameter is between 1.5 mm and 6 mm, and the interval between two adjacent short optical fiber segments is between 0.3 mm and 0.7 mm.

8. A bionic manipulator, characterized in that: The invention comprises a palm and a plurality of fingers connected to the palm, wherein the palm and the fingers are provided with a bending sensor as claimed in any one of claims 1 to 7 for detecting the posture angle of the fingers.

9. The bionic manipulator according to claim 8, characterized in that: The light-emitting element is arranged between the fingertip and the distal knuckle of the finger; the light-guiding module is integrated in the distal knuckle and the proximal knuckle of the finger; the light-mixing module and the light-sensing module are fixed in the palm.

Images