Flexible six-axis force / torque sensing device, system and method based on u-shaped micro / nano fibers

Abstract

A flexible six-axis force / torque sensing device, system and method based on U-shaped micro / nano fibers. The device comprises a flexible elastomer (1), a first U-shaped micro / nano fiber (2-1), a second U-shaped micro / nano fiber (2-2), a third U-shaped micro / nano fiber (2-3) and a fourth U-shaped micro / nano fiber (2-4), wherein the flexible elastomer (1) comprises a floating beam (1-1) on the edge thereof, a boss (1-2) in the center, and a first elastic beam (1-3), a second elastic beam (1-4), a third elastic beam (1-5) and a fourth elastic beam (1-6), which are between the boss (1-2) and the floating beam (1-1); the first U-shaped micro / nano fiber (2-1) and the second U-shaped micro / nano fiber (2-2) are respectively embedded in the lengthwise directions thereof into the first elastic beam (1-3) and the second elastic beam (1-4); the third U-shaped micro / nano fiber (2-3) and the fourth U-shaped micro / nano fiber (2-4) are respectively embedded in the directions of the widths thereof into the third elastic beam (1-5) and the fourth elastic beam (1-6); the first U-shaped micro / nano fiber (2-1) and the second U-shaped micro / nano fiber (2-2) are parallel to a surface of the flexible elastomer (1); and the third U-shaped micro / nano fiber (2-3) and the fourth U-shaped micro / nano fiber (2-4) are perpendicular to the surface of the flexible elastomer (1).

Description

A flexible six-dimensional force / torque sensing device, system, and method based on U-shaped micro / nano optical fibers Technical Field

[0001] This invention relates to force sensing technology, and more particularly to a flexible six-dimensional force / torque sensing device, system, and method based on U-shaped micro / nano optical fibers. Background Technology

[0002] Multi-axis force sensors play a crucial role in robot grasping, manipulation, and human-robot interaction. Traditional rigid six-dimensional force / torque sensors are typically implemented using a rigid crossbeam structure, but the application scenarios for rigid sensors are limited. Therefore, there is a need to develop flexible multi-axis force sensors, which have wide applications in flexible robots, flexible electronic skin, and health monitoring. Flexible multi-axis force sensors are usually implemented using microstructures (pyramid, hemispherical, interdigital structures), and normal and shear forces are measured through different deformations of the microstructure. However, this approach suffers from problems such as signal crosstalk and structural complexity.

[0003] In recent years, optical sensors have been further developed, exhibiting characteristics such as high sensitivity, electrical passivity, and high resolution. Micro- and nano-fiber optics (MNFs) have low transmission loss, high tensile strength, and compatibility with standard optical fibers. Force direction selection can be achieved by observing the change in light intensity after a force is applied to an MNF. This method has low signal crosstalk, a simple structure, and can realize three-dimensional force measurement. For example, patent application number 202411186846.9 discloses a flexible multi-axis force sensor and system based on tapered optical fibers. This scheme uses one or more U-shaped micro- and nano-fibers to sense and measure multi-axis forces, including normal force and transverse shear force. However, this scheme can only achieve three-dimensional force measurement, not three-dimensional torque measurement, and its sensitivity needs improvement. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a flexible six-dimensional force / torque sensing device, system, and method based on U-shaped micro / nano optical fibers that has higher sensitivity and can realize six-dimensional force / torque sensing.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A flexible six-dimensional force / torque sensing device based on U-shaped micro / nano fibers includes a flexible elastomer, a first U-shaped micro / nano fiber, a second U-shaped micro / nano fiber, a third U-shaped micro / nano fiber, and a fourth U-shaped micro / nano fiber. The flexible elastomer includes a floating beam on its edge, a boss at its center, and a first elastic beam, a second elastic beam, a third elastic beam, and a fourth elastic beam between the boss and the floating beam. The first elastic beam, the second elastic beam, the third elastic beam, and the fourth elastic beam are arranged at 90-degree intervals in a clockwise order. The first U-shaped micro / nano fibers and the second U-shaped micro / nano fibers are embedded in the first elastic beam and the second elastic beam, respectively, along their length direction. The third U-shaped micro / nano fibers and the fourth U-shaped micro / nano fibers are embedded in the third elastic beam and the fourth elastic beam, respectively, along their width direction. The planes of the first U-shaped micro / nano fibers and the second U-shaped micro / nano fibers are parallel to the surface of the flexible elastomer, and the planes of the third U-shaped micro / nano fibers and the fourth U-shaped micro / nano fibers are perpendicular to the surface of the flexible elastomer.

[0007] Furthermore, one end of the first elastic beam, the second elastic beam, the third elastic beam, and the fourth elastic beam are respectively connected to the floating beam, and the other end is respectively connected to the boss. The height of the lower surface of the connection between the first elastic beam, the second elastic beam, the third elastic beam, and the fourth elastic beam and the boss is higher than the lower surface of the boss.

[0008] Furthermore, the U-shaped ends of the first U-shaped micro-nano fiber and the second U-shaped micro-nano fiber are respectively close to the protrusion, and the fiber input end and fiber output end protrude out of the first elastic beam and the second elastic beam, respectively.

[0009] Furthermore, the third and fourth U-shaped micro-nano optical fibers are generally close to the protrusion, with the fiber input end and fiber output end protruding outside the third and fourth elastic beams, respectively.

[0010] Furthermore, the flexible elastomer is a PDMS material.

[0011] A flexible six-dimensional force / torque sensing system based on U-shaped micro / nano optical fibers includes the aforementioned flexible six-dimensional force / torque sensing device based on U-shaped micro / nano optical fibers, and further includes a laser, a photodetector, and a computing module. The laser is connected to the fiber input ends of the first, second, third, and fourth U-shaped micro / nano optical fibers via optical fibers. The photodetector is connected to the fiber output ends of the first, second, third, and fourth U-shaped micro / nano optical fibers via optical fibers. The computing module is used to calculate the three-dimensional force and three-dimensional torque based on the light signal detected by the photodetector after applying force / torque to the protrusion.

[0012] Furthermore, the calculation module is specifically used to calculate the three-dimensional force and three-dimensional torque according to the following formula: Fx =f1(ΔI3) F y =f2(ΔI4) M x =f4(ΔI1) M y =f5(ΔI2)

[0013] In the formula, F x F y F z M represents the force components of a three-dimensional force in the x, y, and z directions, respectively. x M y M z Let f1, f2, f3, f4, f5, and f6 represent the components of the three-dimensional torque in the x, y, and z directions, respectively, and let f1, f2, f3, f4, f5, and f6 represent the components of F. x F y F z M x M y M z The relationship function between light intensity and change is ΔI1=I1-I 10 ΔI2=I2-I 20 ΔI3=I3-I 30 ΔI4=I4-I 40 I represents the change in light intensity of the first, second, third, and fourth U-shaped micro / nano fibers when force is applied. 10 I 20 I 30 I 40 I1, I2, I3, and I4 represent the optical intensity at the output ends of the first, second, third, and fourth U-shaped micro-nano fibers when no force is applied, respectively.

[0014] Furthermore, the relational functions f1, f2, f3, f4, f5, and f6 are obtained through the following method:

[0015] When different known forces / torques are applied to the protrusion, the changes in light intensity at the fiber output ends of the first, second, third, and fourth U-shaped micro / nano fibers are recorded. Based on the changes in light intensity and the corresponding known force / torque data, the relationship functions f1, f2, f3, f4, f5, and f6 are obtained through fitting.

[0016] A flexible six-dimensional force / torque sensing method based on U-shaped micro / nano optical fibers is proposed. The method is implemented using the aforementioned flexible six-dimensional force / torque sensing device based on U-shaped micro / nano optical fibers. The method includes...

[0017] Laser is input into the fiber input ends of the first U-shaped micro / nano fiber, the second U-shaped micro / nano fiber, the third U-shaped micro / nano fiber, and the fourth U-shaped micro / nano fiber.

[0018] After applying force / torque to the protrusion, three-dimensional force and three-dimensional torque are calculated based on the optical signals from the output ends of the first, second, third, and fourth U-shaped micro-nano fibers.

[0019] Furthermore, the three-dimensional force and three-dimensional moment are calculated using the following formula: F x =f1(ΔI3) F y =f2(ΔI4) M x =f4(ΔI1) M y =f5(ΔI2)

[0020] In the formula, F x F y F z M represents the force components of a three-dimensional force in the x, y, and z directions, respectively. x M y M z Let f1, f2, f3, f4, f5, and f6 represent the components of the three-dimensional torque in the x, y, and z directions, respectively, and let f1, f2, f3, f4, f5, and f6 represent the components of F. x F y F z M x M y M z The relationship function between light intensity and change is ΔI1=I1-I 10 ΔI2=I2-I 20 ΔI3=I3-I 30 ΔI4=I4-I 40 I represents the change in light intensity of the first, second, third, and fourth U-shaped micro / nano fibers when force is applied. 10 I 20 I 30 I 40 I1, I2, I3, and I4 represent the optical intensity at the output ends of the first, second, third, and fourth U-shaped micro-nano fibers when no force is applied, respectively.

[0021] Compared with the prior art, the beneficial effects of this invention are:

[0022] 1. By combining a flexible elastomer and U-shaped micro / nano optical fibers, the magnitude of force / torque is obtained by measuring the changes in light intensity through four U-shaped micro / nano optical fibers. The direction of the applied force / torque is obtained by measuring the changes in light intensity through U-shaped micro / nano optical fibers of different grades, thus realizing six-dimensional force / torque measurement;

[0023] 2. Based on the photoelastic effect of PDMS, when an elastic beam is deformed under stress, the local refractive index at the deformation location changes, thus locally failing the total internal reflection condition, thereby changing the direction of the reflected light. Macroscopically, this manifests as radiation at the deformation location, resulting in a change in the light intensity at the output end. The magnitude of the six-dimensional force / moment can be measured based on the change in light intensity.

[0024] 3. By uniquely positioning four elastic beams and four micro / nano optical fibers within the elastic beams, the degree of deformation is increased, thereby improving sensitivity;

[0025] 4. Compared with traditional rigid six-dimensional force / moment sensing devices, this invention achieves anisotropy through U-shaped micro-nano optical fibers, thereby enabling the selectivity of force measurement direction. Furthermore, the measurement of six-dimensional force / moment is achieved based on the inconsistent orientation of the U-shaped micro-nano optical fibers embedded in different elastic beams, reducing crosstalk and coupling between six-dimensional forces / moments.

[0026] 5. The flexible elastomer used in this invention is simple to manufacture and has low cost;

[0027] 6. This invention enables the miniaturization of sensors through improvements in manufacturing processes, and features electrical passivity and biocompatibility, allowing for integration into minimally invasive surgical instruments and making it applicable to a wide range of scenarios. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the structure of the flexible six-dimensional force / torque sensing device based on U-shaped micro / nano optical fiber provided in an embodiment of the present invention;

[0029] Figure 2 is a schematic diagram of the structure of the flexible six-dimensional force / torque sensing system based on U-shaped micro / nano optical fiber provided in an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the heated conical stretching method;

[0031] Figure 4 is a schematic diagram of the first and second U-shaped micro / nano fibers ① and ② in the elastic beam, viewed from the top of the flexible elastomer.

[0032] Figure 5 is a schematic diagram of the third and fourth U-shaped micro / nano fibers ③ and ④ in the elastic beam in the side view of the flexible elastomer.

[0033] Figure 6 is a schematic diagram of the deformation of the elastic beam with the boss subjected to the z-direction force and the U-shaped micro / nano fiber.

[0034] Figure 7 is a schematic diagram of the deformation of the elastic beam with the boss subjected to the x-direction force and the U-shaped micro / nano fiber.

[0035] Figure 8 is a schematic diagram of the deformation of the elastic beam and the U-shaped micro / nano fiber under the y-direction force on the boss.

[0036] Figure 9 is a schematic diagram of the deformation of the elastic beam and the U-shaped micro / nano fiber under the z-direction moment of the boss.

[0037] Figure 10 is a schematic diagram of the deformation of the elastic beam and the U-shaped micro / nano fiber under the x-direction moment of the boss.

[0038] Figure 11 is a schematic diagram of the deformation of an elastic beam and a U-shaped micro / nano fiber under a y-direction moment on the boss. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0040] Example 1

[0041] This invention provides a flexible six-dimensional force / torque sensing device based on U-shaped micro / nano optical fibers, as shown in Figures 1 and 2. It includes a flexible elastomer 1 and four U-shaped micro / nano optical fibers 2 (including a first U-shaped micro / nano optical fiber 2-1, a second U-shaped micro / nano optical fiber 2-2, a third U-shaped micro / nano optical fiber 2-3, and a fourth U-shaped micro / nano optical fiber 2-4). The flexible elastomer 1 is made of PDMS material and includes a floating beam 1-1 on its edge, a boss 1-2 at its center, and a first elastic beam 1-3, a second elastic beam 1-4, a third elastic beam 1-5, and a fourth elastic beam 1-6 between the boss 1-2 and the floating beam 1-1. The first elastic beam 1-3, the second elastic beam 1-4, the third elastic beam 1-5, and the fourth elastic beam 1-6 are arranged at 90-degree intervals in a clockwise direction. The first U-shaped micro / nano optical fibers 2-1 and the second U-shaped micro / nano optical fibers... 2-2 are embedded along their length into the first elastic beam 1-3 and the second elastic beam 1-4, respectively. The third U-shaped micro-nano fiber 2-3 and the fourth U-shaped micro-nano fiber 2-4 are embedded along their width into the third elastic beam 1-5 and the fourth elastic beam 1-6, respectively. The planes containing the first U-shaped micro-nano fiber 2-1 and the second U-shaped micro-nano fiber 2-2 are parallel to the surface of the flexible elastomer 1, while the planes containing the third U-shaped micro-nano fiber 2-3 and the fourth U-shaped micro-nano fiber 2-4 are perpendicular to the surface of the flexible elastomer 1. The elastic beams allow for the measurement of the deformation force generated after the protrusion moves, improving sensitivity. Furthermore, the unique positioning of the four U-shaped micro-nano fibers enables six-dimensional force / torque measurement.

[0042] In this configuration, one end of the first elastic beam 1-3, the second elastic beam 1-4, the third elastic beam 1-5, and the fourth elastic beam 1-6 are respectively connected to the floating beam 1-1, and the other end is respectively connected to the boss 1-2. The lower surface of the connection between the first elastic beam 1-3, the second elastic beam 1-4, the third elastic beam 1-5, and the fourth elastic beam 1-6 and the boss 1-2 is higher than the lower surface of the boss 1-2. This increases the deformation of the first elastic beam 1-3, the second elastic beam 1-4, the third elastic beam 1-5, and the fourth elastic beam 1-6 after the boss 1-2 is subjected to force, thereby further improving the sensitivity.

[0043] In this configuration, the U-shaped ends of the first U-shaped micro / nano fiber 2-1 and the second U-shaped micro / nano fiber 2-2 are located close to the protrusion 1-2, with their fiber input and output ends protruding outside the first elastic beam 1-3 and the second elastic beam 1-4, respectively. The third U-shaped micro / nano fiber 2-3 and the fourth U-shaped micro / nano fiber 2-4 are also located close to the protrusion 1-2, with their fiber input and output ends protruding outside the third elastic beam 1-5 and the fourth elastic beam 1-6, respectively. This allows for the connection of optical fibers at both the fiber input and output ends, enabling the input of optical signals and the measurement of output optical signals.

[0044] The manufacturing process of U-shaped micro / nano optical fibers is as follows: Commercially available single-mode SiO2 optical fibers are used as the starting material. SiO2 micro / nano optical fibers are manufactured using a tapered stretching technique, as shown in Figure 3. First, the fiber is heated above the softening point of quartz glass, and then bidirectionally stretched at a constant speed (0.1 mm / s) under the control of a high-precision translation stage. During the stretching process, a 785 nm laser source 9 and an optical power meter 10 are connected to both ends of the fiber to monitor its transmission characteristics in real time. Stretching is stopped when the output light intensity suddenly decreases (due to the cutoff of higher-order modes), thus allowing precise control of the diameter of the U-shaped micro / nano optical fiber. In this embodiment, the diameter of the U-shaped micro / nano optical fiber is 2 μm. The specific steps for manufacturing the flexible elastomer using the parallel capillary constraint method are as follows: Two parallel glass capillary molds are used. The spacing (L0) between the glass capillaries determines the separation distance at the fiber ends, thereby determining the bending radius of the U-shaped micro / nano optical fiber (Rb≈L0 / 2). Optical fibers were passed through a capillary tube, and a layer of PDMS solution (a 10:1 mixture of Dow Corning DC184 base components and curing agent) was drop-coated onto the bottom of a mold for the flexible elastomer to form a substrate layer. U-shaped micro / nano fibers, fixed within the capillary tube, were placed on the elastic beam substrate layer and adhered to the PDMS substrate layer using adhesive. After curing, the glass capillary mold was removed, and another layer of PDMS solution was applied. The mixture was then baked at 40°C for 10 hours to cure. Finally, the flexible elastomer was gently separated from the mold using a release agent, yielding a flexible elastomer with four embedded U-shaped micro / nano fibers.

[0045] The main sensing principle of this invention is as follows: The first U-shaped micro / nano fiber 2-1, the second U-shaped micro / nano fiber 2-2, the third U-shaped micro / nano fiber 2-3, and the fourth U-shaped micro / nano fiber 2-4 are labeled as U-shaped micro / nano fibers ①, ②, ③, and ④, respectively. When an external force is applied to the protrusion of the flexible elastomer, the elastic beam of the flexible elastomer will deform. Due to the photoelastic effect of PDMS, the local refractive index at the deformation location will change, causing the U-shaped micro / nano fiber to switch from waveguide mode to radiation mode. Consequently, the light intensity at the output end of the U-shaped micro / nano fiber changes. The force value and torque magnitude are calculated based on the change in light intensity. Since the distribution of the four U-shaped micro / nano fibers is inconsistent, specifically, as shown in Figure 4, the centerlines of the first and second U-shaped micro / nano fibers ① and ② are parallel to the long axis of the elastic beam. As shown in Figure 5, the centerlines of the third and fourth U-shaped micro / nano fibers ③ and ④ are perpendicular to the long axis of the elastic beam. Clearly, due to the anisotropy of the U-shaped micro / nano fiber, its response to forces / torques in different directions is also inconsistent. We can discuss two cases: First, when the applied force / torque is perpendicular to the surface of the U-shaped micro / nano fiber, it is sensitive to the applied force / torque. Second, when the applied force / torque is parallel to the surface of the U-shaped micro / nano fiber, it is sensitive to forces / torques parallel to the centerline of the U-shaped micro / nano fiber, but insensitive to forces / torques perpendicular to the centerline. The embedding of four micro / nano fibers is intended to produce different responses to forces / torques in different directions, thereby enabling the determination of the force / torque direction.

[0046] Example 2

[0047] This invention provides a flexible six-dimensional force / moment sensing system based on U-shaped micro / nano optical fibers, including the aforementioned flexible six-dimensional force / moment sensing device based on U-shaped micro / nano optical fibers, and further including a laser 5, a photodetector 6, and a computing module 7. The laser 5, photodetector 6, and computing module 7 are all located on a base 8. The laser is connected to the optical fiber input ends of the first U-shaped micro / nano optical fiber 2-1, the second U-shaped micro / nano optical fiber 2-2, the third U-shaped micro / nano optical fiber 2-3, and the fourth U-shaped micro / nano optical fiber 2-4 respectively via optical fiber 3. The photodetector is connected to the optical fiber output ends of the first U-shaped micro / nano optical fiber 2-1, the second U-shaped micro / nano optical fiber 2-2, the third U-shaped micro / nano optical fiber 2-3, and the fourth U-shaped micro / nano optical fiber 2-4 respectively via optical fiber 4. The computing module is used to calculate the three-dimensional force and three-dimensional torque based on the light signal detected by the photodetector after applying force / moment on the boss 1-2.

[0048] As shown in Figure 6, when a force in the z-direction is applied to the protrusion, since the force in the z-direction is perpendicular to the centerline of U-shaped micro / nano fibers ③ and ④, and perpendicular to the surfaces of U-shaped micro / nano fibers ① and ②, the light intensity at the output ends of U-shaped micro / nano fibers ① and ② changes. However, the change in light intensity at the output ends of U-shaped micro / nano fibers ③ and ④ is very small. Since the change in light intensity is the same for U-shaped micro / nano fibers ① and ②, the following expression is obtained:

[0049] As shown in Figure 7, when a force in the x-direction is applied to the protrusion, and this force is parallel to the centerline of the U-shaped micro / nano fiber ③, the change in light intensity of the U-shaped micro / nano fiber ③ is used as a characteristic parameter for calculating the force in the x-direction, thus yielding the expression: F x =f1(ΔI3)

[0050] As shown in Figure 8, when a force in the y-direction is applied to the protrusion, and this force is parallel to the centerline of the U-shaped micro / nano fiber ④, the change in light intensity of the U-shaped micro / nano fiber ④ is used as a characteristic parameter for calculating the force in the y-direction, thus yielding the expression: F y =f2(ΔI4)

[0051] As shown in Figure 9, when a torque in the z-direction is applied to the protrusion, since the torque in the z-direction is perpendicular to the center lines of U-shaped micro / nano fibers ① and ②, and parallel to the center lines of U-shaped micro / nano fibers ③ and ④, the light intensity at the output ends of U-shaped micro / nano fibers ③ and ④ changes. The change in light intensity at the output ends of U-shaped micro / nano fibers ① and ② is very small. Furthermore, since the change in light intensity at U-shaped micro / nano fibers ③ and ④ is consistent, the following expression is obtained:

[0052] As shown in Figure 10, when a torque in the x-direction is applied to the protrusion, and this torque is perpendicular to the plane containing the U-shaped micro / nano fiber ①, the change in light intensity of the U-shaped micro / nano fiber ① is used as a characteristic parameter for calculating the torque in the x-direction, thus yielding the expression: M x =f4(ΔI1)

[0053] As shown in Figure 11, when a torque in the y-direction is applied to the protrusion, and this torque is perpendicular to the plane containing the U-shaped micro / nano fiber ②, the change in light intensity of the U-shaped micro / nano fiber ② is used as a characteristic parameter for calculating the torque in the y-direction, resulting in the expression: M y =f5(ΔI2)

[0054] Where, ΔI1=I1-I 10 ΔI2=I2-I 20 ΔI3=I3-I 30 ΔI4=I4-I 40In Figures 6 to 11, the solid black lines represent the positions of the flexible elastomer and the U-shaped micro / nano fiber before deformation, the solid gray blocks represent the positions of the flexible elastomer after deformation, and the dashed black lines represent the positions of the U-shaped micro / nano fiber after deformation.

[0055] In the formula, F x F y F z M represents the force components of a three-dimensional force in the x, y, and z directions, respectively. x M y M z Let f1, f2, f3, f4, f5, and f6 represent the force components of the three-dimensional torque in the x, y, and z directions, respectively, and let f1, f2, f3, f4, f5, and f6 represent the force components of F. x F y F z M x M y M z The relationship between I and the change in light intensity, ΔI1, ΔI2, ΔI3, ΔI4 represent the changes in light intensity of the first, second, third, and fourth U-shaped micro / nano fibers, respectively. 10 I 20 I 30 I 40 The values ​​represent the optical intensity at the output ends of the first, second, third, and fourth U-shaped micro / nano fibers when no six-dimensional force / torque is applied. I1, I2, I3, and I4 represent the optical intensity at the output ends of the first, second, third, and fourth U-shaped micro / nano fibers when a force is applied, respectively. As can be seen from the above expressions, the direction of the six-dimensional force / torque can be determined by identifying which one or two U-shaped micro / nano fibers experience a change in optical intensity when different forces / torques are applied.

[0056] To obtain the expressions for f1, f2, f3, f4, f5, and f6, when different values ​​of known force / torque are applied to the protrusions 1-2, the changes in light intensity at the fiber output ends of the first, second, third, and fourth U-shaped micro / nano fibers are recorded. Based on the changes in light intensity and the corresponding known force / torque data, the relationship functions f1, f2, f3, f4, f5, and f6 are fitted to obtain the relationship functions.

[0057] A multi-channel photodetector is used to record the light intensity changes of four U-shaped micro / nano optical fibers. The output light intensity of the multi-channel photodetector is transmitted to the calculation module via a data acquisition board. In this embodiment, the data acquisition board uses a frequency of 500Hz.

[0058] The formula for calculating optical transmission loss is:

[0059] Where I represents the light intensity under force / torque, and I0 represents the light intensity without force / torque.

[0060] The calculation module performs noise processing on the acquired signals to remove background noise and interference. It also averages multiple measurements to improve measurement accuracy.

[0061] Regarding environmental control during the measurement of this six-dimensional force / torque measuring device; for the change in output light intensity, the difference between the light intensity under force / torque and the reference light intensity is used, so the output stability of the laser will affect the measurement results. This embodiment controls the measurement from two aspects: vibration isolation and light source: the device is installed on a platform with vibration isolation measures; the experiment requires the use of a laser with high stability to reduce the impact of unstable light source output on the experimental results.

[0062] It is worth noting that in the embodiments of the above system, the various units and modules included are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy distinction between each other and are not used to limit the scope of protection of the present invention.

[0063] The embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art will clearly understand that each implementation can be achieved using software plus necessary general-purpose hardware platforms, or it can be implemented solely through hardware, as long as the function or purpose can be achieved.

[0064] Example 3

[0065] This invention provides a flexible six-dimensional force / torque sensing method based on U-shaped micro / nano optical fibers. The method is implemented based on the flexible six-dimensional force / torque sensing device based on U-shaped micro / nano optical fibers described in Embodiment 1. The method includes...

[0066] Laser is input into the fiber input ends of the first U-shaped micro-nano fiber 2-1, the second U-shaped micro-nano fiber 2-2, the third U-shaped micro-nano fiber 2-3, and the fourth U-shaped micro-nano fiber 2-4;

[0067] After applying force / torque to the boss 1-2, three-dimensional force and three-dimensional torque are calculated based on the optical signals from the output ends of the first U-shaped micro-nano fiber 2-1, the second U-shaped micro-nano fiber 2-2, the third U-shaped micro-nano fiber 2-3, and the fourth U-shaped micro-nano fiber 2-4.

[0068] The three-dimensional force and three-dimensional moment are calculated using the following formula: F x =f1(ΔI3) F y =f2(ΔI4) M x =f4(ΔI1) M y =f5(ΔI2)

[0069] In the formula, F x F y F z M represents the force components of a three-dimensional force in the x, y, and z directions, respectively. x M y M z Let f1, f2, f3, f4, f5, and f6 represent the components of the three-dimensional torque in the x, y, and z directions, respectively, and let f1, f2, f3, f4, f5, and f6 represent the components of F. x F y F z M x M y M z The relationship function between light intensity and change is ΔI1=I1-I 10 ΔI2=I2-I 20 ΔI3=I3-I 30 ΔI4=I4-I 40 I represents the change in light intensity of the first U-shaped micro / nano fiber 2-1, the second U-shaped micro / nano fiber 2-2, the third U-shaped micro / nano fiber 2-3, and the fourth U-shaped micro / nano fiber 2-4 when force is applied. 10 I 20 I 30 I 40 I1, I2, I3, and I4 represent the optical intensity at the output ends of the first U-shaped micro / nano fiber 2-1, the second U-shaped micro / nano fiber 2-2, the third U-shaped micro / nano fiber 2-3, and the fourth U-shaped micro / nano fiber 2-4 when no force is applied, respectively.

[0070] It should be understood that the embodiments and descriptions above are only the principles, main features and advantages of the present invention. Various changes and modifications can be made to the present invention without departing from the spirit and scope of the invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A flexible six-axis force / torque sensor based on U-shaped micro / nano fiber, characterized in that: The flexible elastic body includes a floating beam on the edge, a boss at the center, and first, second, third and fourth elastic beams between the boss and the floating beam, the first, second, third and fourth elastic beams are arranged at an interval of 90 degrees in clockwise order, the first and second U-shaped micro-nano optical fibers are embedded into the first and second elastic beams along the length direction respectively, the third and fourth U-shaped micro-nano optical fibers are embedded into the third and fourth elastic beams along the width direction respectively, the plane where the first and second U-shaped micro-nano optical fibers are located is parallel to the surface of the flexible elastic body, and the plane where the third and fourth U-shaped micro-nano optical fibers are located is perpendicular to the surface of the flexible elastic body.

2. The U-shaped micro-nano fiber based flexible six-axis force / torque sensing device according to claim 1, wherein: One end of each of the first, second, third and fourth elastic beams is connected to the floating beam, and the other end is connected to the boss, and the height of the lower surface of the connection between the first, second, third and fourth elastic beams and the boss is higher than the lower surface of the boss.

3. The U-shaped micro-nano fiber based flexible six-axis force / torque sensor device according to claim 1, wherein: The U-shaped head of each of the first and second U-shaped micro-nano optical fibers is close to the boss, and the optical fiber input end and the optical fiber output end are respectively exposed to the outside of the first and second elastic beams.

4. The U-shaped micro-nano fiber based flexible six-axis force / torque sensor device according to claim 1, wherein: The third and fourth U-shaped micro-nano optical fibers are close to the boss as a whole, and the optical fiber input end and the optical fiber output end are respectively exposed to the outside of the third and fourth elastic beams.

5. The U-shaped micro / nano fiber based flexible six-axis force / torque sensor device according to claim 1, wherein: The flexible elastic body is made of PDMS material. 6.A flexible six-axis force / torque sensing system based on U-shaped micro-nano fiber, characterized in that: The U-shaped micro-nano optical fiber-based flexible six-dimensional force / torque sensing device of claim 1 further comprises a laser, a photodetector and a calculation module, the laser is connected to the optical fiber input end of the first, second, third and fourth U-shaped micro-nano optical fibers through optical fibers respectively, the photodetector is connected to the optical fiber output end of the first, second, third and fourth U-shaped micro-nano optical fibers through optical fibers respectively, and the calculation module is used to calculate three-dimensional force and three-dimensional torque according to the optical signal detected by the photodetector after the force / torque is applied to the boss.

7. The U-shaped micro-nano fiber based flexible six-axis force / torque sensing system according to claim 6, wherein: The computing module is specifically configured to calculate the three-dimensional force and the three-dimensional moment according to the following formulas: F x = f1(ΔI3) F y = f2(ΔI4) M x = f4(ΔI1) M y = f5(ΔI2) wherein F x , F y , F z respectively represent force components of the three-dimensional force in x, y, z directions, M x , M y , M z respectively represent components of the three-dimensional moment in x, y, z directions, f1, f2, f3, f4, f5, f6 respectively represent F x , F y , F z , M x , M y , M z respectively represent the relationship functions between the light intensity variation and the light intensity variation amount, ΔI1=I1-I 10 , ΔI2=I2-I 20 , ΔI3=I3-I 30 , ΔI4=I4-I 40 respectively represent the light intensity variation amounts of the first U-shaped micro-nano fiber, the second U-shaped micro-nano fiber, the third U-shaped micro-nano fiber and the fourth U-shaped micro-nano fiber when the force is applied, I 10 , I 20 , I 30 , I 40 respectively represent the light intensities of the fiber output ends of the first U-shaped micro-nano fiber, the second U-shaped micro-nano fiber, the third U-shaped micro-nano fiber and the fourth U-shaped micro-nano fiber when the force is not applied, I1, I2, I3, I4 respectively represent the light intensities of the fiber output ends of the first U-shaped micro-nano fiber, the second U-shaped micro-nano fiber, the third U-shaped micro-nano fiber and the fourth U-shaped micro-nano fiber when the force is applied.

8. The U-shaped micro-nano fiber based flexible six-axis force / torque sensing system according to claim 7, wherein: The relationship functions f1, f2, f3, f4, f5 and f6 are obtained by the following method: When a known force / torque of different values is applied to the boss, the change amount of the light intensity of the optical fiber output end of the first, second, third and fourth U-shaped micro-nano optical fibers is recorded, and the relationship functions f1, f2, f3, f4, f5 and f6 are obtained by fitting according to the change amount of the light intensity and the data of the corresponding known force / torque.

9. A U-shaped micro-nano optical fiber-based flexible six-dimensional force / torque sensing method, the method is realized based on the U-shaped micro-nano optical fiber-based flexible six-dimensional force / torque sensing device of claim 1, and the method comprises The laser is input to the fiber input end of the first U-shaped micro-nano fiber, the second U-shaped micro-nano fiber, the third U-shaped micro-nano fiber and the fourth U-shaped micro-nano fiber; After the force / torque is applied to the boss, the three-dimensional force and three-dimensional torque are calculated according to the optical signals of the fiber output ends of the first U-shaped micro-nano fiber, the second U-shaped micro-nano fiber, the third U-shaped micro-nano fiber and the fourth U-shaped micro-nano fiber.

10. The U-shaped micro-nano fiber based flexible six-axis force / torque sensing method according to claim 9, wherein: The three-dimensional force and three-dimensional moment are calculated by the following equations: F x = f1(ΔI3) F y = f2(ΔI4) M x = f4(ΔI1) M y = f5(ΔI2) wherein F x , F y , F z respectively represent the force components of the three-dimensional force in the x, y, z directions, M x , M y , M z respectively represent the components of the three-dimensional moment in the x, y, z directions, f1, f2, f3, f4, f5, f6 respectively represent F x , F y , F z , M x , M y , M z respectively represent the relationship functions between the light intensity variation and the light intensity variation amount, ΔI1 = I1 - I 10 , ΔI2 = I2 - I 20 , ΔI3 = I3 - I 30 , ΔI4 = I4 - I 40 respectively represent the light intensity variation amounts of the first, second, third and fourth U-shaped micro-nano optical fibers when the force is applied, I 10 , I 20 , I 30 , I 40 respectively represent the light intensities of the fiber output ends of the first, second, third and fourth U-shaped micro-nano optical fibers when no force is applied, I1, I2, I3, I4 respectively represent the light intensities of the fiber output ends of the first, second, third and fourth U-shaped micro-nano optical fibers when the force is applied.

Images