Flexible conjugate double-curvature optical waveguide sensor and application method thereof in flexible joint measurement

Abstract

The invention discloses a flexible conjugate double-curvature optical waveguide sensor and an application method of the flexible conjugate double-curvature optical waveguide sensor in flexible joint measurement. The flexible conjugate double-curvature optical waveguide sensor comprises two sensing assemblies and a flexible substrate, wherein each sensing assembly comprises a double-curvature optical waveguide, a flexible coating layer, a light emitting device and a light intensity detection device; for each sensing assembly, the light-emitting device and the light intensity detection device are installed at the two ends of the double-curvature optical waveguide respectively, and the outer side of the double-curvature optical waveguide is evenly wrapped with the flexible wrapping layer. The two sensing assemblies are attached to the upper surface of the flexible base body side by side and can deform along with deformation of the base body, and the installation direction of the sensing assemblies is the same as the direction of the flexible base body. According to the flexible conjugate double-curvature optical waveguide sensor and the application method of the flexible conjugate double-curvature optical waveguide sensor in flexible joint measurement, the influence of transverse bending deformation of the sensor on longitudinal tension and compression deformation measurement is effectively reduced, and the tension and compression and omnidirectional bending deformation of the flexible joint can be measured at the same time; and the precision and comprehensiveness of the measurement function of the sensor are ensured.

Description

Technical Field

[0001] This invention belongs to the field of flexible robot technology, specifically a flexible conjugate hypercurvature optical waveguide sensor and its application method in flexible joint measurement. Background Technology

[0002] Flexible robots are robots constructed primarily from soft, elastic, and deformable materials. Flexible joints are the parts that undergo significant deformation. Accurate measurement of flexible joint deformation is a prerequisite for achieving precise end-effector control of flexible robots. The measurement of flexible joints requires obtaining the amount of joint extension and omnidirectional bending deformation.

[0003] Due to the flexibility, extensibility, and omnidirectional bending of joint materials, it is difficult to measure flexible joints using the angle measurement methods commonly used for rigid robot joints. Currently, the sensing methods used for motion state feedback of flexible joints mainly include resistive sensors, capacitive sensors, magnetic sensors, liquid metal sensors, and inertial measurement units. These methods generally suffer from poor electromagnetic interference resistance and insufficient compatibility with flexible joint integration. Flexible optical waveguide sensors, with their lightweight structure, good integration with flexible structures, and low susceptibility to external electromagnetic field interference, have significant advantages in flexible joint measurement.

[0004] In existing technologies, commonly used straight waveguides are only suitable for measuring large changes in the bending angle of flexible joints, with low measurement accuracy, and cannot measure the amount of joint extension and contraction deformation and the direction of bending motion. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] To address the problems mentioned above, the commonly used straight waveguides in the prior art are only suitable for measuring large bending angle changes in flexible joints, have low measurement accuracy, and cannot measure the amount of joint extension and contraction deformation and the direction of bending motion. The present invention adopts the following technical solution.

[0007] A flexible conjugate hypercurvature optical waveguide sensor includes two sensing components and a flexible substrate; each of the sensing components includes a hypercurvature optical waveguide, a flexible cladding layer, a light-emitting device, and a light intensity detection device. For each of the sensing components, the light-emitting device and the light intensity detection device are respectively installed at both ends of the hyperbolic waveguide, and the flexible cladding layer is uniformly wrapped around the outside of the hyperbolic waveguide. The two sensing components are attached side by side to the upper surface of the flexible substrate and can deform synchronously with the deformation of the flexible substrate. The mounting direction of the sensing components is consistent with the extension direction of the flexible substrate.

[0008] Preferably, when the hypercurvature optical waveguide in the sensing component is not deformed, its baseline is a planar wavy line; the planar wavy line is formed by alternating ends of two arc segments with opposite bending directions and different arc radii, and all arcs have equal central angles.

[0009] Preferably, the hyperbolic waveguides of the two sensing components are interlocked according to the difference in the arc radius of their respective baseline segments; and the intersection of all adjacent arc segments on the baseline of the hyperbolic waveguides is located on the center line of the upper surface of the flexible substrate.

[0010] Preferably, the light-emitting device is a laser diode or an LED light source, and the light intensity detection device is a photodiode or a photovoltaic cell.

[0011] Preferably, the flexible coating layer is made of silicone or polyimide, and the flexible substrate is made of elastic polyurethane or flexible polycarbonate.

[0012] A method for applying a flexible conjugate hypercurvature optical waveguide sensor to the measurement of flexible joints, wherein the flexible conjugate hypercurvature optical waveguide sensor is deployed for measuring the extension and omnidirectional bending deformation of the flexible joint as follows: four flexible conjugate hypercurvature optical waveguide sensors, after pre-stretching deformation treatment, are attached to the surface of the flexible joint along the axial direction, and the four sensors are evenly distributed at 90° intervals along the circumference of the flexible joint; the attachment surface between the sensor and the flexible joint is the lower surface of the flexible substrate.

[0013] Preferably, in the application method, the step of calculating the deformation of the flexible joint includes: Step 1: Obtain the emitted light intensity setpoints of the four sensors (a total of eight light-emitting devices) and the received light intensity measurement values ​​of the eight light intensity detection devices; calculate the eight light fluxes based on the emitted light intensity setpoints and received light intensity measurement values. Step 2: For each sensor, select the larger value of the luminous flux corresponding to its two sensing components as the luminous flux of that sensor; Step 3: Based on the luminous flux of the four sensors, extract three deformation characterization parameters, namely the average luminous flux of the four sensors, the luminous flux difference of the first pair of sensors, and the luminous flux difference of the second pair of sensors; wherein, the first pair of sensors and the second pair of sensors are two sets of sensors arranged opposite each other along the circumference of the flexible joint.

[0014] Preferably, in the application method, the step of calculating the deformation of the flexible joint further includes: Step 4: Within the tensile-compression deformation domain and omnidirectional bending deformation domain of the flexible joint, load the flexible joint and uniformly sample to obtain multiple sets of sample data pairs of "three deformation characterization parameters - actual deformation of the flexible joint". Step 5: Using machine learning algorithms, a proxy model for calculating joint deformation is generated based on the sample data; Step 6: During actual measurement, the three deformation characterization parameters measured in real time are input into the joint deformation calculation proxy model, and the model outputs the tensile and compressive deformation and omnidirectional bending deformation of the flexible joint.

[0015] Preferably, the machine learning algorithm mentioned in the steps is a support vector machine algorithm, a random forest algorithm, or an artificial neural network algorithm.

[0016] Preferably, the stretching amount of the pre-stretching deformation treatment is 10%-30% of the maximum elastic deformation of the flexible conjugate hypercurvature optical waveguide sensor.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The flexible conjugate hypercurvature optical waveguide sensor of the present invention uses a curved waveguide as a sensing element, realizing the measurement of tensile and compressive deformation using an optical waveguide, thus expanding the application scenarios of flexible optical waveguide sensing technology.

[0018] 2. The flexible conjugate double curvature optical waveguide sensor of the present invention adopts a double curvature bent optical waveguide design and a double waveguide conjugate arrangement, which effectively reduces the influence of the transverse bending deformation of the sensor on the longitudinal tensile and compressive deformation measurement, and ensures the accuracy of the sensor's tensile and compressive deformation measurement.

[0019] 3. The flexible conjugate hypercurvature optical waveguide sensor of the present invention adopts a bidirectional aligned arrangement. When measuring the movement of a flexible joint, it can not only measure the omnidirectional bending deformation of the flexible joint, but also simultaneously measure the extension and contraction deformation of the flexible joint.

[0020] 4. The flexible conjugate hypercurvature optical waveguide sensor of the present invention has a compact structure, is lightweight and thin, occupies little space, is easy to install, has stable performance, and can be used for deformation measurement of flexible structures of different scales after being serialized. Attached Figure Description

[0021] Figure 1 This is a schematic diagram showing the installation position of the sensor of the present invention on the flexible joint; Figure 2 This is a schematic diagram of the overall structure of the sensing component of the present invention; Figure 3 This is a front view schematic diagram of the flexible substrate of the present invention; Figure 4 This is a schematic cross-sectional view of the flexible coating layer of the present invention; Figure 5 For the present invention Figure 3 Enlarged structural diagram of section A in the middle.

[0022] The correspondence between the labels and component names in the attached figures is as follows: 100. Flexible conjugate hypercurvature optical waveguide sensor; 110. Sensing component; 120. Flexible substrate; 111. Hypercurvature optical waveguide; 112. Flexible cladding layer; 113. Light emission device; 114. Light intensity detection device. Detailed Implementation

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0024] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places throughout this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that mutually excludes other embodiments. The present invention provides the following embodiments.

[0026] Please see Figure 1-5 The present invention provides an embodiment of a flexible conjugate hypercurvature optical waveguide sensor 100 and its application method in flexible joint measurement, such as... Figure 2-5 As shown, the flexible conjugate hyperbolic optical waveguide sensor 100 includes two sensing components 110 and a flexible substrate 120; each of the sensing components 110 includes a hyperbolic optical waveguide 111, a flexible cladding layer 112, a light-emitting device 113, and a light intensity detection device 114; the light-emitting device 113 is a laser diode or an LED light source, and the light intensity detection device 114 is a photodiode or a photovoltaic cell.

[0027] For each of the sensing components 110, the light-emitting device 113 and the light intensity detection device 114 are respectively installed at both ends of the hyperbolic waveguide 111, and the flexible cladding layer 112 is uniformly wrapped around the outside of the hyperbolic waveguide 111; the flexible cladding layer 112 is made of silicone or polyimide, and the flexible substrate 120 is made of elastic polyurethane or flexible polycarbonate.

[0028] Two of the sensing components 110 are attached side by side to the upper surface of the flexible substrate 120 and can deform synchronously with the deformation of the flexible substrate 120. The mounting direction of the sensing components 110 is consistent with the extension direction of the flexible substrate 120.

[0029] In this embodiment, when the hyperbolic waveguide 111 in the sensing component 110 is not deformed, its baseline is a planar wavy line. The planar wavy line is formed by alternating arc segments with opposite curvature directions and unequal radii, with all arcs having equal central angles. The hyperbolic waveguides 111 of the two sensing components 110 are interlocked according to the difference in the radii of their respective baseline arc segments. Furthermore, the intersection points of all adjacent arc segments on the baseline of the hyperbolic waveguide 111 are located on the center line of the upper surface of the flexible substrate 120. When no deformation is applied, the baseline of the hyperbolic waveguides 111 of the two sensing components 110 is a planar wavy line, formed by two arc segments with opposite curvature directions and unequal radii, with radii R1 and R2 respectively. Two sensing components 110 are arranged on the flexible substrate 120 in such a way that both are adhered to the same side surface of the flexible substrate 120. The intersection of all two arcs on the baseline of the hyperbola optical waveguide 111 of one sensor component 110 is located on the center line of the upper surface of the flexible substrate 120. The baseline of the hyperbola optical waveguide 111 of this sensing component 110 is symmetrical about the center line of the upper surface of the flexible substrate 120. Then, half a cycle length of the wavy line is translated along this line. The cycle length refers to the length of an adjacent arc segment with radius R1 and radius R2 along the direction of the center line of the upper surface of the flexible substrate 120. The baseline position of the hyperbola optical waveguide 111 of the other sensor component is obtained.

[0030] A method for applying a flexible conjugate hypercurvature optical waveguide sensor 100 to the measurement of flexible joints, wherein the flexible conjugate hypercurvature optical waveguide sensor 100 is deployed for measuring the extension and omnidirectional bending deformation of flexible joints as follows: four pre-stretched and deformed flexible conjugate hypercurvature optical waveguide sensors 100 are attached to the surface of the flexible joint along the axial direction, and the four sensors are evenly distributed at 90° intervals along the circumference of the flexible joint; the attachment surface between the sensor and the flexible joint is the lower surface of the flexible substrate 120, and the stretching amount of the pre-stretching and deforming treatment is 10%-30% of the maximum elastic deformation of the flexible conjugate hypercurvature optical waveguide sensor 100.

[0031] In this embodiment, the calculation step of the flexible joint deformation in the application method includes: Step 1: Obtain the emitted light intensity setpoints of the four sensors (a total of eight light-emitting devices 113) and the received light intensity measurement values ​​of the eight light intensity detection devices 114, and calculate the eight light fluxes based on the emitted light intensity setpoints and received light intensity measurement values.

[0032] Step 2: For each sensor, select the larger value of the luminous flux corresponding to its two sensing components 110 as the luminous flux of that sensor.

[0033] Step 3: Based on the luminous flux of the four sensors, extract three deformation characterization parameters, namely the average luminous flux of the four sensors, the luminous flux difference of the first pair of sensors, and the luminous flux difference of the second pair of sensors; wherein, the first pair of sensors and the second pair of sensors are two sets of sensors arranged opposite each other along the circumference of the flexible joint.

[0034] In this embodiment, the calculation step of the flexible joint deformation in the application method further includes: Step 4: Within the tensile-compression deformation domain and omnidirectional bending deformation domain of the flexible joint, load the flexible joint and uniformly sample it to obtain multiple sets of sample data pairs of "three deformation characterization parameters - actual deformation of the flexible joint".

[0035] Step 5: Using a machine learning algorithm, a joint deformation calculation proxy model is generated based on the sample data; the machine learning algorithm is a support vector machine algorithm, a random forest algorithm, or an artificial neural network algorithm.

[0036] Step 6: During actual measurement, the three deformation characterization parameters measured in real time are input into the joint deformation calculation proxy model, and the model outputs the tensile and compressive deformation and omnidirectional bending deformation of the flexible joint.

[0037] like Figure 1As shown, a spatial rectangular coordinate system OXYZ is established on the cylindrical flexible joint, where the Z-axis coincides with the central axis of the flexible joint. When measuring the extension and omnidirectional bending deformation of the flexible joint, four flexible conjugate hypercurvature optical waveguide sensors 100 are attached along the Z-direction at the intersection of the XOZ plane, the YOZ plane and the surface of the flexible joint, respectively. The lower surface of the flexible substrate 120 of each sensor is attached to the surface of the flexible joint.

[0038] When the flexible conjugate hyperbolic optical waveguide sensor 100 of the present invention measures the extension and omnidirectional bending deformation of a flexible joint, the data acquisition and processing method is as follows: The light intensity input by the light-emitting device 113 to the hyperbolic optical waveguide 111 of a certain hyperbolic optical waveguide 111 of the sensor is defined as P. in The hyperbolic waveguide 111 outputs a light intensity of P to the light intensity detection device 114. out Let η = P out / P in This represents the numerical value of its luminous flux.

[0039] Take the larger η value of each of the two hypercurvature optical waveguides 111 of the sensor in the positive X direction, negative X direction, positive Y direction, and negative Y direction as η1, η2, η3, and η4 respectively, and calculate three deformation characterization parameters p=(η1+η2+η3+η4) / 4, q=η2-η1, and r=η4-η3. The three deformation characterization parameters p, q, and r characterize the Z-direction extension deformation and the bending deformation on the Y-axis and X-axis of the flexible joint, respectively.

[0040] By loading the flexible joint within its stretching and omnidirectional bending deformation domains and uniformly sampling, we obtain data pairs of p, q, and r with the actual deformation samples of the flexible joint in the Z-axis stretching and the Y-axis and X-axis bending. We then use machine learning to train and generate a surrogate model for joint deformation calculation. In practical applications, we measure three deformation characterization parameters. Using the surrogate model, we can calculate the deformation of the flexible joint in real time during stretching and omnidirectional bending, thus realizing its function.

[0041] The above description, in conjunction with specific embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection defined by the claims submitted herein.

Claims

1. A flexible conjugate hypercurvature optical waveguide sensor (100), characterized in that, It includes two sensing components (110) and a flexible substrate (120); each of the sensing components (110) includes a hyperbolic optical waveguide (111), a flexible cladding layer (112), a light-emitting device (113), and a light intensity detection device (114). For each of the sensing components (110), the light-emitting device (113) and the light intensity detection device (114) are respectively installed at both ends of the hyperbolic waveguide (111), and the flexible cladding layer (112) is uniformly wrapped around the outside of the hyperbolic waveguide (111). Two of the sensing components (110) are attached side by side to the upper surface of the flexible substrate (120) and can deform synchronously with the deformation of the flexible substrate (120). The mounting direction of the sensing components (110) is consistent with the extension direction of the flexible substrate (120).

2. The flexible conjugate hypercurvature optical waveguide sensor (100) according to claim 1, characterized in that: When the hypercurvature optical waveguide (111) in the sensing component (110) is not deformed, its baseline is a planar wavy line; the planar wavy line is formed by alternating ends of two arc segments with opposite bending directions and different arc radii, and all arcs have the same central angle.

3. The flexible conjugate hypercurvature optical waveguide sensor (100) according to claim 2, characterized in that: The hyperbolic waveguides (111) of the two sensing components (110) are interlocked according to the difference in the radius of their respective baseline arc segments; and the intersection of all adjacent arc segments on the baseline of the hyperbolic waveguides (111) is located on the center line of the upper surface of the flexible substrate (120).

4. The flexible conjugate hypercurvature optical waveguide sensor (100) according to claim 1, characterized in that: The light-emitting device (113) is a laser diode or an LED light source, and the light intensity detection device (114) is a photodiode or a photovoltaic cell.

5. The flexible conjugate hypercurvature optical waveguide sensor (100) according to claim 1, characterized in that: The flexible covering layer (112) is made of silicone or polyimide, and the flexible substrate (120) is made of elastic polyurethane or flexible polycarbonate.

6. A method for applying a flexible conjugate hypercurvature optical waveguide sensor (100) to the measurement of flexible joints, wherein the sensor is applied to the flexible conjugate hypercurvature optical waveguide sensor (100) as described in any one of claims 1-5, characterized in that: In the application method, the flexible conjugate hyperbola optical waveguide sensor (100) is deployed for measuring the extension and omnidirectional bending deformation of a flexible joint as follows: four flexible conjugate hyperbola optical waveguide sensors (100) that have undergone pre-stretching deformation treatment are attached to the surface of the flexible joint along the axial direction of the flexible joint, and the four sensors are evenly distributed at 90° intervals along the circumference of the flexible joint; the attachment surface between the sensor and the flexible joint is the lower surface of the flexible substrate (120).

7. The application method according to claim 6, characterized in that, In the application method, the steps for calculating the deformation of the flexible joint include: Step 1: Obtain the emitted light intensity setpoint of the four sensors (a total of eight light-emitting devices (113) and the received light intensity measurement value of the eight light intensity detection devices (114), and calculate the eight light fluxes based on the emitted light intensity setpoint and the received light intensity measurement value; Step 2: For each sensor, select the larger value of the luminous flux corresponding to its two sensing components (110) as the luminous flux of that sensor; Step 3: Based on the luminous flux of the four sensors, extract three deformation characterization parameters, namely the average luminous flux of the four sensors, the luminous flux difference of the first pair of sensors, and the luminous flux difference of the second pair of sensors; wherein, the first pair of sensors and the second pair of sensors are two sets of sensors arranged opposite each other along the circumference of the flexible joint.

8. The application method according to claim 7, characterized in that, The application method further includes the following steps for calculating the deformation of the flexible joint: Step 4: Within the tensile-compression deformation domain and omnidirectional bending deformation domain of the flexible joint, load the flexible joint and uniformly sample to obtain multiple sets of sample data pairs of "three deformation characterization parameters - actual deformation of the flexible joint". Step 5: Using machine learning algorithms, a proxy model for calculating joint deformation is generated based on the sample data; Step 6: During actual measurement, the three deformation characterization parameters measured in real time are input into the joint deformation calculation proxy model, and the model outputs the tensile and compressive deformation and omnidirectional bending deformation of the flexible joint.

9. The application method according to claim 8, characterized in that, The machine learning algorithm mentioned in step 5 is a support vector machine algorithm, a random forest algorithm, or an artificial neural network algorithm.

10. The application method according to claim 6, characterized in that, The stretching amount of the pre-stretching deformation treatment is 10%-30% of the maximum elastic deformation of the flexible conjugate hypercurvature optical waveguide sensor (100).

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