An exoskeleton interactive force sensor based on fiber grating

Abstract

The application discloses an exoskeleton interactive force sensor based on an optical fiber grating, which comprises a sensitivity sensor I, a human-computer interaction binding structure and a sensitivity sensor II; the human-computer interaction binding structure is designed in a C-shaped hollow structure, and is used for realizing compliant binding with a human body; the sensitivity sensor I and the sensitivity sensor II are arranged at two ends of the outer side of the C-shaped hollow structure of the human-computer interaction binding structure respectively; the human-computer interaction binding structure comprises an arc-shaped binding structure and an arc-shaped binding structure, and two pairs of the arc-shaped binding structure and the arc-shaped binding structure are used for wrapping thighs; and the arc-shaped binding structure and the arc-shaped binding structure are connected through an adaptive adjustment structure. The application realizes high-sensitivity human-computer interaction force detection.

Description

Technical Field

[0001] This invention relates to the field of exoskeleton interactive force sensor technology, and specifically to an exoskeleton interactive force sensor based on a fiber Bragg grating. Background Technology

[0002] In the field of knee joint rehabilitation training and assistance, exoskeleton robot technology has shown great potential. However, existing exoskeleton systems, especially their core force interaction sensing components, still face many technical bottlenecks that limit their widespread application.

[0003] Traditional force sensors, such as strain gauge sensors, while technologically mature, are susceptible to electromagnetic interference, making it difficult to guarantee measurement stability and accuracy in complex electromechanical environments. Furthermore, the signal transmission of these sensors typically requires cables, increasing the complexity of system wiring and the burden on moving parts, impacting the portability and reliability of the equipment. For exoskeleton robots, accurate and lightweight human-machine interaction force sensing is crucial. Existing exoskeletons often combine force sensing units with rigid structural components, resulting in large sensor sizes and weights. This undermines the portability that exoskeletons should prioritize, increases the patient's additional load, and affects wearing comfort and natural movement. Moreover, traditional force detection solutions are complex in structure and have low integration, making it difficult to achieve distributed, multi-point force measurement and accurately capture the distribution of human-machine interaction forces.

[0004] In exoskeleton control, the lack of lightweight and precise force sensing feedback makes it difficult for devices to achieve truly smooth and safe human-machine interaction. Many devices have to rely on complex dynamic models and indirect force estimation methods, which not only impose a heavy computational burden but also limit control accuracy and response speed, posing potential risks.

[0005] Therefore, there is an urgent need for a lightweight sensing solution that can directly and accurately measure interaction forces while also being inherently safe, highly resistant to interference, and easy to integrate with structures. Existing fiber Bragg grating-based sensing technologies have proven to have advantages such as resistance to electromagnetic interference, light weight, and ease of forming sensor networks in other fields (such as three-dimensional force measurement in surgical robots). However, its innovative application to the accurate detection of human-machine interaction forces in exoskeleton robots, especially in solving the aforementioned challenges of lightweight design, interference resistance, and distributed measurement, remains a technical direction that requires further exploration.

[0006] It should be noted that directly applying fiber optic grating (FBG) technology to human-machine interaction force detection in exoskeletons still faces several key engineering challenges. FBG sensing units are highly sensitive to strain changes, but their output signals are also affected by temperature variations. During exoskeleton wear, additional drift errors are easily generated due to body temperature, frictional heating, and ambient temperature fluctuations. Without effective temperature compensation structures or algorithms, measurement accuracy and long-term stability will be affected. Secondly, the sensor requires a reliable design of the force-strain transmission path to ensure structural stiffness matching and strain amplification efficiency, maintaining the sensor's sensitivity and stability. Furthermore, the fiber itself is somewhat brittle and sensitive to bending radii and repeated cyclic loading. Under the repeated flexion and extension and soft tissue deformation environment of the exoskeleton, improper encapsulation design can easily lead to fiber micro-damage, stress concentration, or fatigue failure. Its design needs to be integrated with the exoskeleton binding structure design to ensure good and stable force measurement performance during wear. Against this backdrop, the application of fiber optic gratings to accurate human-machine interaction force detection in exoskeleton robots still faces technical shortcomings that need to be overcome. Summary of the Invention

[0007] To overcome the shortcomings of the existing technology, the present invention provides an exoskeleton interactive force sensor based on fiber optic grating. The exoskeleton interactive force sensor can detect tensile and compressive forces, and realize highly sensitive human-computer interaction force detection.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An exoskeleton interactive force sensor based on fiber Bragg grating includes a first sensitive sensor, a human-computer interaction binding structure, and a second sensitive sensor. The human-computer interaction binding structure is a C-shaped hollow design, which is used to achieve flexible binding with the human body. This amplifies the linear deformation of the sensor body under pressure when the same amount of interactive force is transmitted. The linear deformation is amplified most significantly in the weakest root area of ​​the sensor, thereby achieving the effect of enhancing sensitivity. The human-computer interaction binding structure is divided into symmetrically arranged and identical arc-shaped binding structures and arc-shaped binding structures, which wrap around the thighs through two pairs of arc-shaped binding structures and arc-shaped binding structures; the arc-shaped binding structures and arc-shaped binding structures are connected by an adaptive adjustment structure; Among them, an enhanced sensor one is installed at the outer end of the arc-shaped binding structure, and an enhanced sensor two is installed at the outer end of the arc-shaped binding structure.

[0009] The human-computer interaction binding structure is used to adjust the opening and closing of the arc-shaped binding structure, thereby achieving comfortable interaction and allowing the sensor to fit snugly against the thigh to ensure the transmission of interaction force. The first and second enhanced sensors have the same structure. The packaging structure of the first or second enhanced sensor includes an enhanced structure body, an optical fiber body, an FBG measuring point one and an FBG measuring point two. The FBG measuring point one and FBG measuring point two are fixed to the high strain region of the sensitizing structure main body and the medium elastic beam through an adhesive layer. The high-strain region of the elastic beam is at its root. When the elastic beam is under stress, the root region experiences significant bending strain; therefore, placing FBG measuring points in this region can improve strain sensing sensitivity.

[0010] The main body of the sensitizing structure is a plate structure, and its outer contour is a U-shaped or approximately U-shaped frame structure. The two sides and the bottom side of the U-shaped structure enclose and form an upward-facing structural shape. The U-shaped structure is provided with mounting through holes at its four corners to enable connection with external fixed structures; The U-shaped structure is provided with an elastic beam structure for strain amplification on the inner side. The elastic beam structure is located in the inner cavity area of ​​the U-shaped frame and forms an integral or integral processing structure with the U-shaped structure. The central region of the sensitizing structure is provided with a force-bearing through hole for transmitting external interactive forces, and an elastic element can be installed in the force-bearing through hole.

[0011] The optical fiber body is arranged along the surface of the elastic beam structure and fixed in the high strain region of the elastic beam; FBG measuring points one and two on the optical fiber body are respectively set on opposite sides or symmetrically on the same elastic beam to detect the strain signal generated by the bending deformation of the elastic beam. When the elastic beam undergoes bending deformation under the action of central force, tensile and compressive strains are generated on both sides of the elastic beam, causing the corresponding FBG measuring points to produce wavelength drift in opposite directions. By differentially processing the signals from the two measuring points, a strain amplification effect can be achieved, thereby improving the overall sensitivity of the sensor and enhancing its temperature compensation capability.

[0012] The optical fiber body is strain-coupled to the elastic beam structure by adhesive bonding or encapsulation, so that the deformation of the elastic beam can be effectively transmitted to the FBG measuring point.

[0013] The sensitizing structure has mounting holes and is fixed to the fixing fixture by bolts; The fixing clamp has clearance grooves on the front and rear sides of the optical fiber bonding area. This is to prevent interference between the optical fiber body and the fixing clamp when the sensitization structure body is fixed, thereby ensuring the positioning accuracy of the optical fiber and the packaging quality.

[0014] The thickness of the sensitizing structure is 1-2mm, and it is a square or near-square plate structure. The sensitizing structure is fixed to the fixing fixture by bolts through mounting holes. Its overall dimensions are designed according to application requirements, and the main material is preferably spring steel with good elasticity and fatigue strength.

[0015] The elastic beam structure is a symmetrically arranged beam structure used to convert externally applied interactive forces into bending deformation; the length, width and thickness of the elastic beam can be adjusted within a preset range according to sensitivity requirements to achieve force-strain conversion and strain amplification effects. The elastic beam structure is a symmetrically arranged double beam structure or an H-shaped beam structure, with its two ends connected to the sidewalls of the U-shaped structure, and the middle part being a free deformation region. The elastic beam undergoes bending deformation under stress, and a strain concentration zone is formed near the root of the beam.

[0016] The main body of the sensitivity-enhancing structure is equipped with an elastic beam structure for strain amplification. The elastic beam structure is a symmetrically arranged beam structure used to convert externally applied interactive forces into bending deformation. The length, width and thickness of the elastic beam can be adjusted within a preset range according to the sensitivity requirements to achieve force-strain conversion and strain amplification effects.

[0017] The sensitive enhancement structure has a force-bearing through hole at its center, and a soft protruding rubber piece is installed inside the through hole. In the working state, the human-machine interaction force is transmitted to the sensitive enhancement structure through the soft protruding rubber piece and acts on the elastic beam structure, causing the elastic beam to produce controllable bending deformation.

[0018] A fiber grating is attached to the high-strain region of the elastic beam. When the elastic beam undergoes bending deformation, the fiber grating generates axial strain, thereby causing Bragg wavelength drift. The wavelength change is detected in real time by the fiber grating demodulation system, enabling the measurement of human-computer interaction force. The enhanced sensor structure has mounting through holes around its main body for fixing the enhanced sensor to the human-machine interaction binding structure, thereby achieving stable installation and effective load transfer.

[0019] Through the above structure, the present invention realizes the mechanical transmission path of center loading—elastic beam bending—fiber grating strain, which can improve detection sensitivity while ensuring structural compactness, and has good anti-electromagnetic interference capability and wearable integration adaptability.

[0020] The optical fiber body includes fiber Bragg grating (FBG) measurement point one and FBG measurement point two disposed on the optical fiber body. These two measurement points are areas on the optical fiber body with FBG grating regions engraved on them. The FBG measurement points are formed at different positions on the optical fiber body through a writing process, and each measurement point has a different center wavelength. The center wavelength of each FBG measurement point is distributed in the range of 1530nm to 1565nm, and the center wavelength interval between adjacent measurement points is not less than the preset value to avoid wavelength overlap or signal interference. The length of the FBG gate area is preferably 3-5 mm to match the strain area layout requirements of the sensitization structure; The reflection spectrum of the FBG has a narrow bandwidth, preferably less than 0.2 nm, and the side-mode suppression ratio is preferably greater than 15 dB, so as to improve wavelength recognition accuracy and signal stability.

[0021] Several mounting holes are provided on the outer edge of the binding structure for connecting the flexible pad and binding fastener; a square groove is provided below the mounting holes for accommodating and positioning the enhanced sensor 1; mounting holes are provided at the four corners of the square groove, and the mounting holes correspond to the mounting holes on the enhanced sensor to achieve fixed installation of the sensor. The outer wall of the square groove is provided with at least two pairs of transverse slender grooves to provide a clearance channel for the optical fiber routing, thereby reducing assembly interference and protecting the optical fiber; the central area of ​​the square groove adopts a hollow structure to place a soft protruding rubber that comes into contact with the human body, so that the human-computer interaction force can be transmitted to the enhanced sensor through the soft protruding structure. A threading hole is provided below the square groove for threading and fixing the flexible pad; a triangular protrusion is provided below the threading hole, and the triangular protrusion has a through hole, which is used with a threaded part to anchor and fix the pad thread to improve the stability of the binding structure. The bottom of the arc-shaped binding structure is provided with a cylindrical platform, and the middle of the cylindrical platform is provided with a through hole for threaded connection; the through hole is provided with several positioning holes symmetrically arranged in the center for inserting cylindrical pins, thereby realizing the positioning and fixed connection between the binding structure and the meshing pinion one and the meshing pinion two.

[0022] The flexible pad is installed using a threaded tensioning method. One end of the rope is first anchored at a triangular protrusion on one side, then passes around the inner side of sleeve one, is guided to the threading hole above the triangular protrusion, and passes through to the other side of the binding structure. The rope continues to pass through the flexible pad, reaches the threading hole at a symmetrical position on the other side and exits, then passes around sleeve two at a symmetrical position on the other side, and is finally anchored again at the triangular protrusion at a symmetrical position on the other side, thus completing the fixed installation of the bottom flexible pad.

[0023] By adjusting the effective length (or tension) of the cord, the fit height and pretension of the flexible padding relative to the binding structure can be changed, thus achieving adaptive adjustment of the actual wearing binding height.

[0024] The adaptive adjustment structure includes pinion 1, pinion 2, pinion 3, pinion 4, bearing 1, bearing 2, connecting plate 1, connecting plate 2, sleeve 1, and sleeve 2. Pinion 1 meshes with pinion 3, and pinion 2 meshes with pinion 4. The opening and closing degree of the binding structure is adjusted by the two pairs of meshing pinions. Each pinion has a large central hole and several smaller holes around it. During assembly, the pinions are inserted into the middle of the side columnar platforms of arc-shaped binding structure 1 and arc-shaped binding structure 2, respectively, and fixed to arc-shaped binding structure 1 and arc-shaped binding structure 2 by cylindrical pins. The fixing structure composed of arc-shaped binding structure 1, pinion 1, and pinion 2 is fixedly connected to connecting plate 1 and connecting plate 2 on both sides by threaded nuts. The center of the columnar platform... The reserved holes are the connection holes; in the same way, the fixing structure composed of arc-shaped binding structure two, pinion three and pinion four is connected to connecting plate one and connecting plate two respectively on both sides by threaded nuts; shaft seat one and shaft seat two are connected to connecting plate two through the set fixing holes. At this time, the structure formed by connecting arc-shaped binding structure one, pinion one, pinion two, arc-shaped binding structure two, pinion three, pinion four, connecting plate one, connecting plate two, shaft seat one and shaft seat two can be assembled into the exoskeleton through the two large round holes in the middle of connecting plate one and connecting plate two; The first curved leg wrap has an upper binding and fixing position for installing the binding strap. The second curved leg wrap has a corresponding fixing position for installing fasteners. In actual use, the fasteners at both ends are fastened together to achieve fixation, thereby forming a circumferential constraint on the human limbs.

[0025] The beneficial effects of this invention are: 1. Enables highly sensitive human-computer interaction force detection. By setting up an elastic beam sensitization structure and placing FBG measuring points in the high-strain region of the elastic beam, when the center is subjected to force, the elastic beam bends and deforms, causing the fiber optic grating to generate a large axial strain, thereby achieving force-strain amplification and improving detection sensitivity.

[0026] 2. The interactive force sensor enables differential detection and temperature compensation. By arranging two FBG measuring points on opposite sides of the same elastic beam, tensile and compressive strain signals are generated respectively under bending conditions. Differential processing enhances the strain response amplitude while reducing the impact of temperature drift on the measurement results, thus improving detection stability and accuracy.

[0027] 3. The compact structure integrates the interactive force sensor and the binding structure. By placing a flexible protruding force-bearing unit at the center of the structure, the human-machine interaction force is concentrated and transferred to the high-strain region of the elastic beam, constructing a clear mechanical transmission path of "central loading—elastic beam bending—fiber grating strain," thereby reducing interference from non-target stresses and improving the accuracy and stability of interactive force measurement. Simultaneously, this integrated and lightweight design achieves real-time interactive force detection without significantly increasing the wearable size and weight, enhancing wearing comfort and the overall user experience.

[0028] 4. The interactive force sensor possesses excellent anti-electromagnetic interference capabilities. This invention employs fiber optic gratings for signal detection, independent of electrical signal transmission, effectively avoiding interference from exoskeleton drive motors or complex electromagnetic environments on the measurement signal, thus improving system reliability. Attached Figure Description

[0029] Figure 1 This is an isometric view of the overall structure of the present invention.

[0030] Figure 2 This is a structural diagram of the enhanced sensor of the present invention.

[0031] Figure 3 This is a schematic diagram showing the location of the fiber optic grid region of the present invention on the sensor.

[0032] Figure 4 This invention relates to a fixture for fabricating fiber optic sensors.

[0033] Figure 5 This is a structural diagram of the interactive binding structure of the present invention.

[0034] Figure 6 This is an exploded view of the overall structure of the present invention.

[0035] Figure 7 This is an example of the interactive force data under the gait motion of the treadmill according to the present invention.

[0036] In the picture: 1. Sensitizing Sensor I; 2. Human-Machine Interaction Binding; 3. Arc-Shaped Binding Structure I; 4. Arc-Shaped Binding Structure II; 5. Soft Protruding Rubber II; 6. Sensitizing Sensor II; 7. Soft Protruding Rubber I; 8. Sleeve I; 9. Connecting Plate I; 10. Pinion I; 11. Pinion II; 12. Pinion III; 13. Shaft Seat I; 14. Pinion IV; 15. Shaft Seat II; 16. Sleeve II; 17. Connecting Plate II. Detailed Implementation

[0037] The present invention will now be described in further detail with reference to the accompanying drawings.

[0038] like Figure 1As shown, the present invention provides an exoskeleton interactive force sensor based on fiber optic grating, including a first-sensitivity sensor 1, a human-computer interaction binding structure 2, and a second-sensitivity sensor 6; the first-sensitivity sensor 1 and the second-sensitivity sensor 6 are respectively disposed on both sides of the human-computer interaction binding structure 2.

[0039] The enhanced sensor 1 has four mounting holes around its perimeter and is fixed to the arc-shaped binding structure 3 via a threaded connection. The enhanced sensor 1 has a central through-hole, at which a soft, raised rubber 7 is installed. In operation, the soft, raised rubber 7 contacts the human thigh to transmit human-machine interaction force to the enhanced sensor body.

[0040] like Figure 3 As shown, based on the force characteristics of the C-shaped hollow structure of the enhanced sensor, Figure 3 The root region 1-5 of the elastic beam marked in the figure is a high-strain region. The fiber optic grating is pasted in this region to obtain a higher strain response sensitivity.

[0041] The bonding process of fiber Bragg gratings is as follows Figure 3 and Figure 4 As shown, the fixing fixtures 1-7 are used to position and fix the enhanced sensor 1.

[0042] The fixing clamp 1-7 has mounting holes on both sides and a hole in the middle for fixing the sensor. The fixing clamp 1-7 has fine grooves on both sides that are aligned with the elastic beam structure 1-6 to define the bonding position of the optical fiber body 1-2.

[0043] like Figures 2-4 As shown, the main body 1-1 of the sensitizing structure is a plate structure, and its outer contour is a U-shaped or approximately U-shaped frame structure. The two sides and the bottom side of the U-shaped structure enclose and form an upward-facing structural shape. The U-shaped structure is provided with mounting through holes at its four corners to enable connection with external fixed structures; The U-shaped structure is provided with an elastic beam structure 1-6 for strain amplification on the inner side. The elastic beam structure is located in the inner cavity area of ​​the U-shaped frame and forms an integral or integral processing structure with the U-shaped structure. The central region of the sensitizing structure 1-1 is provided with a force-bearing through hole for transmitting external interactive forces, and an elastic element may be provided in the force-bearing through hole.

[0044] The optical fiber body 1-2 is arranged along the surface of the elastic beam structure 1-6 and fixed to the high strain region 1-5 of the elastic beam; The FBG measuring points 1-3 and 1-4 on the optical fiber body 1-2 are respectively set on the opposite sides or symmetrical positions of the same elastic beam to detect the strain signal generated by the bending deformation of the elastic beam. The optical fiber body 1-2 is strain-coupled to the elastic beam structure 1-6 by adhesive bonding or encapsulation, so that the deformation of the elastic beam can be effectively transmitted to the FBG measuring point.

[0045] The sensitization structure body 1-1 is provided with mounting holes and is fixed to the fixing clamp 1-7 by bolts; The fixing clamps 1-7 are provided with clearance grooves on the front and back sides of the optical fiber pasting area.

[0046] The thickness of the sensitizing structure 1-1 is 1-2mm, and it is a square or approximately square structure. The elastic beam structures 1-6 are symmetrically arranged double beam structures or H-shaped beam structures, used to convert externally applied interactive forces into bending deformation; the length, width and thickness of the elastic beams can be adjusted within a preset range according to sensitivity requirements to achieve force-strain conversion and strain amplification effects; both ends are connected to the side walls of the U-shaped structure, and the middle part is a free deformation area; The elastic beam undergoes bending deformation under stress, and a strain concentration zone is formed near the root of the beam.

[0047] The FBG (Fiber Bragg Grating) is bonded to the root region of the elastic beam using structural adhesive (preferably ND353 adhesive). Before bonding, appropriate pre-tightening force is applied to the fiber optic bodies 1-2. After bonding, it is preferably kept at 80°C for 30 minutes, then allowed to cool naturally to room temperature for curing. After curing, multiple load-unload cycles are performed within the sensor's measurement range to release residual stress generated during curing, ensuring that the deformation of the metal elastic beam can be effectively transmitted to the fiber Bragg grating.

[0048] This invention uses a fiber Bragg grating (FBG) as the detection core. When the fiber body 1-2 is subjected to external strain, the grating period and effective refractive index change, resulting in a shift in the Bragg reflection wavelength. By monitoring the wavelength change, the deformation changes caused by human-machine interaction force can be reflected, thus realizing the measurement of interaction force.

[0049] Regarding the fabrication steps of the enhanced sensor: The first step is to wipe the fiber body 1-2 with alcohol or other cleaning agents before FBG encapsulation to remove surface dust and impurities; then, use a fiber optic cleaver to trim the end face of the fiber body 1-2 to make the end face flat, so as to ensure stable optical performance. The second step involves fixing the sensitizing structure body 1-1 to the fixing fixture 1-7 using bolts. The optical fiber body 1-2, with FBG grid areas engraved on it, is placed into a pre-set groove in the fixing fixture 1-7. This groove ensures the optical fiber remains directly above the elastic beam structure 1-6. The FBG grid areas corresponding to FBG measuring points 1-3 and 1-4 are aligned with the high-strain region at the root of the elastic beam and kept close to the surface of the elastic beam. The third step involves applying a pre-set tension force to both ends of the fiber optic body 1-2 to eliminate additional internal stress generated during the subsequent adhesive curing process. Then, structural adhesive (preferably ND353 adhesive or a similar bonding material) is used to attach the FBG measurement points to the reserved area, ensuring that external interaction forces are effectively transferred to the grating area. The fourth step is to place the component in a constant temperature environment for curing. The preferred curing temperature is 70℃~90℃, and it should be maintained for a preset time to complete the cross-linking and curing of the adhesive. After curing, allow it to cool naturally to room temperature. After completing the encapsulation on one side, encapsulate the other side of the elastic beam in the same way. The fifth step is to apply multiple loading-unloading cycles within the sensor's measurement range after encapsulation. The loading range is preferably 0–300N to release the residual stress generated during the curing process and enable the sensor to reach a stable working state.

[0050] Specifically, the second enhanced sensor 6 is manufactured using the same process as the first enhanced sensor 1, and its structure and shape design are the same as or correspond to those of the first enhanced sensor 1.

[0051] like Figure 5 As shown, the human-computer interaction binding structure 2 includes an arc-shaped binding structure 3 and an arc-shaped binding structure 4. The outer side of the arc-shaped binding structure has mounting holes 3-1 for mounting binding straps. During installation, the binding straps are fixed to the mounting holes using threaded fittings, thus achieving a fixed connection between the binding structure and the human thigh.

[0052] The inner side of the arc-shaped binding structure has a square groove, and mounting holes 3-2 are provided around the groove, corresponding to the mounting holes of the enhanced sensor-1. The sidewall of the groove has transverse grooves 3-3 for accommodating fiber optic cables. The center of the groove has a hollow structure, corresponding to the soft raised rubber-7, for transmitting interaction forces.

[0053] The square groove has a threading hole 3-4 and a triangular protrusion 3-5 on its side. The threading hole is used to thread and fix the flexible pad, and the triangular protrusion serves as an anchor point for the thread. One end of the thread is fixed to the triangular protrusion 3-5, passes through the sleeve 1 8 and the threading hole 3-4, passes through the flexible pad, extends to the opposite side structure, wraps back through the sleeve 2 16, and is fixed to the opposite triangular protrusion, thus achieving tensioned installation of the flexible pad. By adjusting the tension of the thread, the fit height of the flexible pad can be adjusted, improving wearing comfort.

[0054] like Figure 6As shown, the adaptive adjustment mechanism includes pinion 10, pinion 2 11, pinion 3 12, pinion 4 14, bearing 1 13, bearing 2 15, connecting plate 1 9, and connecting plate 2 17. The two pairs of pinions mesh to achieve synchronous opening and closing of the arc-shaped binding structure. The pinions are fixed to the cylindrical platform of the arc-shaped binding structure by cylindrical pins. The connecting plates and bearings are fixed by threaded parts, making the two binding structures form an integral adjustable mechanism. By adjusting the meshing position of the pinions, the degree of opening and closing of the binding structure can be adjusted, allowing the soft raised rubber 7 to conform to the human thigh.

[0055] The working process of this invention is as follows: First, the fiber optic grating area is attached to the root region of the elastic beam, and the sensor assembly is completed. Then, by adjusting the opening and closing of the binding structure, the soft protruding rubber is made to fit the thigh. Finally, during the movement, the interaction force is transmitted to the elastic beam through the soft protruding rubber, causing a change in the wavelength of the fiber optic grating, thereby realizing the measurement of the interaction force.

[0056] In one specific embodiment, the interactive force sensor of the present invention is installed on the thigh segment of the lower limb exoskeleton. First, by adjusting the adaptive adjustment mechanism, the arc-shaped binding structure 3 and the arc-shaped binding structure 4 are opened and closed to a size suitable for the subject's thigh circumference. Then, the binding structure is fitted to the outer thigh and secured with straps.

[0057] By adjusting the meshing positions of pinion 10, pinion 21, pinion 312 and pinion 414, the two arc-shaped binding structures open and close synchronously, ensuring that the soft raised rubber 7 can evenly adhere to the surface of the outer thigh muscles.

[0058] In a static state, the sensor is in an initial zero-strain state. When the exoskeleton is driven or the human body actively moves, an interaction force is generated between the thigh and the binding structure. This interaction force is concentrated and transmitted to the central region of the sensitive sensor 1 through the soft protruding rubber 7, causing elastic bending deformation of the C-shaped hollow structure. High strain is generated in the root region of the elastic beam, and this strain is transmitted to the fiber optic grating attached to its surface, causing Bragg wavelength drift.

[0059] During walking, when the body enters the support phase, the thigh muscles generate significant interactive pressure, increasing the amplitude of the fiber Bragg grating output wavelength shift. In the oscillating phase, the interactive force decreases, and the wavelength shift decreases accordingly. Wavelength changes are collected in real time using a fiber Bragg grating demodulator, and the corresponding interactive force is calculated based on the calibration curve.

[0060] In different exercise modes (such as stepping, squatting, and walking on a treadmill), the changes in interactive force exhibit different periodic curve characteristics, verifying the applicability of this invention in dynamic exercise environments. Figure 7As shown, the curves exhibiting the interaction force variation pattern in treadmill gait exercise modes show differences in curve shape across different exercise modes, reflecting variations in human-machine interaction force. All curves demonstrate continuous and distinguishable trends, indicating that the sensor of this invention can measure human-machine interaction force information in real time under different exercise modes, thus achieving the human-machine interaction force detection function.

[0061] The interactive force sensor of this invention realizes human-computer interactive force measurement through a mechanical transmission path of "human body - soft raised rubber - sensitive enhancement structure body - elastic beam - fiber optic grating".

[0062] Specifically, when worn, the arc-shaped binding structure 3 and the arc-shaped binding structure 4 adjust their opening and closing angles through an adaptive adjustment mechanism (including pinion 10, pinion 21, pinion 312, and pinion 414), ensuring that the soft raised rubber 7 is stably fitted to the outer side of the thigh. The connecting plates 9 and 17, along with the bearings 13 and 15, ensure that the binding structures on both sides remain relatively parallel during movement.

[0063] When human movement or exoskeleton actuation generates human-machine interaction force, the interaction force first acts on the soft protruding rubber-7. Since the rubber is located at the central through-hole of the sensitive sensor-1, the force is concentrated and transmitted to the C-shaped hollow area of ​​the sensitive sensor structure body 1-1, causing the body to undergo overall compressive deformation.

[0064] Because the sensitizing structure adopts a C-shaped hollow design, the load is mainly converted into bending deformation of the elastic beam during the transmission process. The root of the elastic beam is a high-strain region, and FBG measuring points 1-3 and 1-4, which are attached to this region, are located on the front and back sides of the elastic beam, respectively.

[0065] When the elastic beam bends, tensile strain is generated on one side and compressive strain is generated on the other side, which causes the two FBG measuring points to produce Bragg wavelength shifts in opposite directions.

[0066] The wavelength changes at FBG measuring points 1-3 and 1-4 are acquired in real time using a fiber optic grating demodulator and differentially processed to eliminate common-mode drift caused by temperature and simultaneously amplify strain. Based on the pre-calibrated wavelength-force mapping relationship, the magnitude of the human-machine interaction force at the corresponding positions of soft protruding rubber 7 and soft protruding rubber 5 can be calculated.

[0067] The mechanism by which this invention achieves human-computer interactive force measurement is as follows: Before wearing the binding structure, use a specific adhesive to attach FBG measurement points 1-3 and FBG measurement points 1-4 to the root area 1-5 of the elastic beam, and adjust the fiber routing to embed the fiber into the transverse groove 3-3.

[0068] After wearing the binding structure, the sensor sensing part is brought close to the thigh by adjusting the arc binding structure 1 3 and arc binding structure 2 4 to ensure that the interaction force can be transmitted to the sensor. At the same time, the optical fiber body 1-2 is connected to the demodulator to ensure that the optical fiber body 1-2 can transmit light to the grating area normally.

[0069] When exercising while wearing the exoskeleton, the legs interact with the binding structure, which compresses the soft protruding rubber 7 and soft protruding rubber 5 of the sensor, transmitting strain to the root region 1-5 of the elastic beam. The resulting deformation is transmitted to fiber optic FBG measuring points 1-3 and 1-4, causing a change in the wavelength of the grating reflection, thereby deriving and calculating the human-machine interaction force.

[0070] Compared with existing exoskeleton force sensors, this sensor has strong anti-interference capabilities due to its use of fiber optic gratings. It is also highly integrated with the binding structure, making it suitable for different testing environments. The C-shaped hollow structure significantly increases its sensitivity, enabling it to handle scenarios with weak interaction forces. The adjustable opening and closing structure also enhances the adaptability of the structure, allowing it to accurately measure the magnitude of interaction forces for people with different leg thicknesses.

[0071] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the specific implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. An exoskeleton interactive force sensor based on a fiber Bragg grating, characterized in that, It includes a first-sensitivity sensor (1), a human-computer interaction binding structure (2), and a second-sensitivity sensor (6). The human-computer interaction binding structure (2) is a C-shaped hollow structure, and the human-computer interaction binding structure (2) is used to achieve flexible binding with the human body; The human-computer interaction binding structure (2) is divided into two symmetrically arranged and identical arc binding structures (3) and (4), which wrap the thighs with two pairs of arc binding structures (3) and (4); the arc binding structures (3) and (4) are connected by an adaptive adjustment structure. Among them, an enhanced sensor 1 (1) is provided at the outer end of the arc-shaped binding structure (3), and an enhanced sensor 2 (6) is provided at the outer end of the arc-shaped binding structure (4).

2. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 1, characterized in that, The first (1) and the second (6) of the enhanced sensor have the same structure. The packaging structure of the first (1) or the second (6) of the enhanced sensor includes the enhanced structure body (1-1), the optical fiber body (1-2), the first FBG measuring point (1-3) and the second FBG measuring point (1-4). The FBG measuring points 1 (1-3) and FBG measuring points 2 (1-4) are fixed to the high strain region (1-5) of the elastic beam in the main body of the sensitizing structure (1-1) by an adhesive layer. The high-strain region of the elastic beam is at the root of the elastic beam.

3. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 2, characterized in that, The main body of the sensitizing structure (1-1) is a plate structure, and its outer contour is a U-shaped or approximately U-shaped frame structure. The two sides and bottom of the U-shaped structure enclose and form an upward-facing structural shape. The U-shaped structure is provided with mounting through holes at its four corners to enable connection with external fixed structures; The U-shaped structure is provided with an elastic beam structure (1-6) for strain amplification. The elastic beam structure is located in the inner cavity area of ​​the U-shaped frame and forms an integral or integral processing structure with the U-shaped structure. The central region of the sensitizing structure body (1-1) is provided with a force-bearing through hole for transmitting external interactive forces, and an elastic element is provided inside the force-bearing through hole.

4. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 3, characterized in that, The optical fiber body (1-2) is arranged along the surface of the elastic beam structure (1-6) and fixed to the high strain region (1-5) of the elastic beam. The FBG measuring point one (1-3) and FBG measuring point two (1-4) on the optical fiber body (1-2) are respectively set on the opposite sides or symmetrical positions of the same elastic beam to detect the strain signal generated by the bending deformation of the elastic beam. The optical fiber body (1-2) is strain-coupled to the elastic beam structure (1-6) by adhesive bonding or encapsulation, so that the deformation of the elastic beam can be effectively transmitted to the FBG measuring point.

5. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 4, characterized in that, The sensitizing structure body (1-1) is provided with mounting holes and is fixed to the fixing clamp (1-7) by bolts; The fixing clamp (1-7) has clearance grooves on the front and back sides of the optical fiber pasting area.

6. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 5, characterized in that, The thickness of the sensitizing structure (1-1) is 1-2 mm, and it is a square or approximately square structure; The elastic beam structure (1-6) is a symmetrically arranged beam structure used to convert externally applied interactive forces into bending deformation; the length, width and thickness of the elastic beam can be adjusted within a preset range according to sensitivity requirements to achieve force-strain conversion and strain amplification effects. The elastic beam structure (1-6) is a symmetrically arranged double beam structure or a H-shaped beam structure, with its two ends connected to the sidewalls of the U-shaped structure, and the middle part being a free deformation area; The elastic beam undergoes bending deformation under stress, and a strain concentration zone is formed near the root of the beam.

7. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 6, characterized in that, The enhanced sensor (1) has a force-bearing through hole at its center, and a soft protruding rubber (7) is installed inside the through hole. Fiber gratings (1-3) are attached to the high-strain region of the elastic beam. The main body of the sensitivity enhancement structure is provided with mounting through holes around its perimeter for fixing the sensitivity enhancement sensor to the human-computer interaction binding structure.

8. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 7, characterized in that, The optical fiber body (1-2) includes fiber Bragg grating (FBG) measurement point one (1-3) and FBG measurement point two (1-4) disposed on the optical fiber body (1-2). These two measurement points are areas on the optical fiber body (1-2) where the FBG grating region is etched. The FBG measurement points are formed at different positions on the optical fiber body (1-2) through a writing process, and each measurement point has a different center wavelength. The center wavelength of each FBG measurement point is distributed in the range of 1530nm to 1565nm, and the center wavelength interval between adjacent measurement points is not less than the preset value to avoid wavelength overlap or signal interference. The length of the FBG gate region is on the order of 3-5 millimeters; The FBG has a narrow bandwidth in its reflection spectrum, less than 0.2 nm, and preferably a side-mode suppression ratio greater than 15 dB.

9. The exoskeleton interactive force sensor based on fiber Bragg grating according to claim 1, characterized in that, The arc-shaped binding structure (3) or arc-shaped binding structure (4) has the same structure. The outer edge of the arc-shaped binding structure (3) is provided with several mounting holes (3-1) for connecting the flexible pad and the binding fastener. A square groove is provided below the mounting hole (3-1) for accommodating and positioning the enhanced sensor (1). Mounting holes (3-2) are provided at the four corners of the square groove. The mounting holes (3-2) correspond to the mounting holes on the enhanced sensor 1 to achieve fixed installation of the sensor. The outer wall of the square groove is provided with at least two pairs of transverse slender grooves (3-3) to provide a passage for optical fiber routing; the central area of ​​the square groove adopts a hollow structure to place a soft protruding rubber (7) that comes into contact with the human body, so that the human-computer interaction force can be transmitted to the sensitive sensor (1) through the soft protruding structure. A threading hole (3-4) is provided below the square groove for threading and fixing the flexible pad; a triangular protrusion (3-5) is provided below the threading hole (3-4), and a through hole is provided on the triangular protrusion (3-5); The bottom of the arc-shaped binding structure (3) is provided with a columnar platform (3-7), and the middle of the columnar platform (3-7) is provided with a through hole for threaded connection; the through hole is provided with a number of positioning holes (3-6) arranged symmetrically at the center.

10. The exoskeleton interactive force sensor based on a fiber Bragg grating according to claim 9, characterized in that, The adaptive adjustment structure includes pinion one (10), pinion two (11), pinion three (12), pinion four (14), bearing one (13), bearing two (15), connecting plate one (9), connecting plate two (17), sleeve one (8) and sleeve two (16). Pinion 1 (10) meshes with pinion 3 (12), and pinion 2 (11) meshes with pinion 4 (14). The opening and closing degree of the binding structure is adjusted by the two pairs of meshing pinions. Each small gear has a large central hole and small holes around it. During assembly, the small gears are inserted into the middle of the side columnar platform (3-7) of the arc-shaped binding structure one (3) and the arc-shaped binding structure two (4), and fixed to the arc-shaped binding structure one (3) and the arc-shaped binding structure two (4) by cylindrical pins. The fixing structure composed of the arc-shaped binding structure one (3), the small gear one (10) and the small gear two (11) is fixedly connected to the connecting plate one (9) and the connecting plate two (17) on both sides by threaded nuts. The hole left in the center of the columnar platform (3-7) is its connection hole. In the same manner, the fixed structure consisting of arc-shaped binding structure 2 (4), pinion 3 (12) and pinion 4 (14) is connected to connecting plate 1 (9) and connecting plate 2 (17) respectively by threaded nuts on both sides; shaft seat 1 (13) and shaft seat 2 (15) are fixedly connected to connecting plate 2 (17) through the set fixed holes. At this time, the adaptive adjustment structure is assembled to the exoskeleton through the two large round holes in the middle of connecting plate 1 (9) and connecting plate 2 (17).

Images