Force sensor, auxiliary system based on force sensor and loading force measuring method

Abstract

The invention relates to the technical field of tactile feedback, and discloses a force sensor, an auxiliary system based on the force sensor and a loading force measuring method.The force sensor comprises a birefringent optical fiber which is provided with a first fiber bragg grating and a second fiber bragg grating which are arranged in the light propagation direction; the first fiber bragg grating and the second fiber bragg grating have different central wavelengths; and under the condition that the birefringent fiber is subjected to loading force, the first fiber grating and the second fiber grating are used for measuring the dependent variable and the temperature variation of the birefringent fiber. The method comprises the following steps: acquiring respective wavelength shifts of a first fiber grating and a second fiber grating through a force sensor; the dependent variable and the temperature variation of the birefringent optical fiber are determined according to the wavelength shift; and performing stress calculation and temperature compensation according to the dependent variable and the temperature variation to obtain a loading force. The beneficial effects are that the accuracy of the tactile feedback result is improved, the integration of the sensing equipment is improved, and further miniaturization of the sensing equipment is supported.

Description

Technical Field

[0001] The present application relates to the technical field of tactile feedback, and in particular to a force sensor, an auxiliary system based on the force sensor, and a loading force measurement method. Background Art

[0002] With the rapid development of medical technology, minimally invasive surgery has become the mainstream trend of modern surgical operations. However, minimally invasive surgery will expose medical staff to radiation. In order to solve the above problems, robot-assisted minimally invasive surgery is usually used to achieve remote and automated minimally invasive surgery, thereby reducing the risk of potential harm to medical staff. When performing surgery with a robot, the accuracy and safety of the surgery are reduced because medical staff cannot directly receive tactile feedback. Therefore, it is necessary to provide a tactile feedback mechanism with high accuracy and sensitivity for minimally invasive surgery. In the related art, the commonly used tactile feedback mechanism is greatly affected by temperature and the corresponding equipment is highly complex. Summary of the invention

[0003] The present application provides a force sensor, an auxiliary system based on the force sensor, and a loading force measurement method, which utilizes the birefringence properties of birefringent optical fiber and the wavelength offset of different fiber gratings to achieve tactile feedback with temperature compensation through a single optical fiber, thereby improving the accuracy of the tactile feedback results while achieving the technical effect of improving the integration of the sensing device and supporting further miniaturization of the sensing device.

[0004] In order to achieve the above objectives, the main technical solutions adopted in this application include:

[0005] In a first aspect, an embodiment of the present application provides a force sensor, comprising a birefringent optical fiber, wherein the birefringent optical fiber has a first optical fiber grating and a second optical fiber grating arranged in a light propagation direction, wherein the first optical fiber grating and the second optical fiber grating have different central wavelengths;

[0006] When the birefringent optical fiber is subjected to a loading force, the first optical fiber Bragg grating and the second optical fiber Bragg grating are used to measure the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force; wherein the strain and the temperature change are determined based on the wavelength offset of the first optical fiber Bragg grating and the second optical fiber Bragg grating, respectively.

[0007] The force sensor proposed in the embodiment of the present application uses a birefringent optical fiber with a first fiber grating and a second fiber grating for loading force sensing, and obtains the wavelength offset of each of the first fiber grating and the second fiber grating according to the central wavelength of each fiber grating and the birefringent property of the birefringent optical fiber, thereby obtaining the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force on the birefringent optical fiber. The present application uses multiple wavelength offsets as data basis, and measures the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force, thereby reducing the influence of the temperature change on the calculation result of the loading force, and improving the accuracy of the tactile feedback result. In addition, compared with the technical solution of setting a reference optical fiber to eliminate the influence of the temperature change in the related art, the present application realizes tactile feedback with temperature compensation through a single optical fiber, improves the stability and integration of the force sensor, and enables the force sensor and the auxiliary system based on the force sensor to be further miniaturized, providing strong technical support for the development of robot-assisted surgery technology.

[0008] Optionally, the birefringent optical fiber comprises a polarization-maintaining optical fiber.

[0009] Optionally, the force sensor further includes an optical fiber sleeve, the birefringent optical fiber is passed through the optical fiber sleeve, and the number of the birefringent optical fiber is one.

[0010] In a second aspect, an embodiment of the present application provides an auxiliary system based on a force sensor, characterized in that it includes the force sensor described in the above embodiment.

[0011] Optionally, the auxiliary system further comprises a broadband light source and a polarization controller;

[0012] The wavelength range of the broadband light source covers the central wavelengths of the first fiber grating and the second fiber grating;

[0013] The polarization controller is used to perform polarization modulation on the light emitted by the broadband light source and output target polarized light for transmission to the birefringent optical fiber.

[0014] Optionally, the auxiliary system further comprises a circulator and a spectrometer:

[0015] The circulator is used to transmit the target polarized light to the birefringent optical fiber, and transmit the first reflected light of the target polarized light by the first optical fiber grating and the second reflected light of the target polarized light by the second optical fiber grating to the spectrometer;

[0016] The spectrometer is used to determine the wavelength shift of the first fiber grating and the second fiber grating respectively.

[0017] In a third aspect, an embodiment of the present application provides a method for measuring a loading force, the method comprising:

[0018] When the birefringent optical fiber is subjected to a loading force, the wavelength shift of each of the first optical fiber Bragg grating and the second optical fiber Bragg grating is obtained by using the force sensor as described in the above embodiment;

[0019] Determining the strain and temperature variation of the birefringent optical fiber according to the wavelength shifts of the first optical fiber grating and the second optical fiber grating;

[0020] The loading force is obtained by performing stress calculation and temperature compensation according to the strain and temperature variation of the birefringent optical fiber.

[0021] The loading force measurement method proposed in the embodiment of the present application uses the wavelength shift of the first fiber grating and the second fiber grating to perform wavelength demodulation to obtain the strain and temperature change of the birefringent optical fiber, calculates the strain according to the strain, and performs temperature compensation on the strain calculation result according to the temperature change to obtain the loading force on the birefringent optical fiber. The present application uses the force sensor described in the above embodiment to simultaneously measure the strain and temperature change of the birefringent optical fiber, and automatically performs temperature compensation on the loading force sensing result according to the temperature change, thereby reducing the influence of the temperature change on the loading force sensing result and improving the accuracy of the tactile feedback result.

[0022] Optionally, determining the strain and temperature change of the birefringent optical fiber according to the wavelength shifts of the first optical fiber grating and the second optical fiber grating comprises:

[0023] Demodulating the wavelength offsets of the first fiber grating and the second fiber grating by using a wavelength demodulation principle formula to obtain a set of wavelength demodulation equations related to the strain and the temperature change;

[0024] The wavelength demodulation equations are solved simultaneously to obtain the strain and the temperature change.

[0025] Optionally, obtaining the wavelength shift of each of the first fiber grating and the second fiber grating includes:

[0026] Acquire a first reflection spectrum of the first fiber grating and a second reflection spectrum of the second fiber grating; wherein the first reflection spectrum includes a first fast-axis reflection spectrum and a first slow-axis reflection spectrum, and the second reflection spectrum includes a second fast-axis reflection spectrum and a second slow-axis reflection spectrum;

[0027] Performing spectral shift analysis on the first fast-axis reflection spectrum and the first slow-axis reflection spectrum to obtain a first wavelength shift and a second wavelength shift of the first fiber grating;

[0028] A spectrum shift analysis is performed on the second fast-axis reflection spectrum and the second slow-axis reflection spectrum to obtain a third wavelength shift and a fourth wavelength shift of the second fiber grating.

[0029] Optionally, the strain includes three-dimensional strain; and determining the strain and temperature change of the birefringent optical fiber according to the wavelength shift of each of the first optical fiber grating and the second optical fiber grating comprises:

[0030] constructing four demodulation equations about the three-dimensional strain and the temperature variation according to the first wavelength shift, the second wavelength shift, the third wavelength shift and the fourth wavelength shift;

[0031] The four demodulation equations are solved simultaneously to obtain the three-dimensional strain and the temperature change. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 A structural diagram of a force sensor provided in an embodiment of the present application;

[0034] Figure 2 A structural diagram of an auxiliary system based on a force sensor provided in an embodiment of the present application;

[0035] Figure 3 A step diagram of a loading force measurement method provided in an embodiment of the present application;

[0036] Figure 4 A diagram showing the steps for obtaining the strain and temperature variation in the embodiment of the present application;

[0037] Figure 5 A diagram showing the steps for obtaining multiple wavelength shifts in an embodiment of the present application;

[0038] Figure 6 A diagram showing the steps for obtaining three-dimensional strain and temperature variation in an embodiment of the present application;

[0039] Figure 7 A module diagram of a loading force measurement system provided in an embodiment of the present application;

[0040] Figure 8 A schematic diagram of the structure of a computer device provided in an embodiment of the present application.

[0041] The figure numbers of the drawings in the specification are as follows: 110. birefringent optical fiber, 120. first optical fiber grating, 130. second optical fiber grating, 140. optical fiber sleeve, 210. broadband light source, 220. polarization controller, 230. circulator, 240. birefringent optical fiber, 250. spectrometer. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0043] With the rapid development of medical technology, minimally invasive surgery has become the mainstream trend of modern surgical operations with its significant advantages such as less trauma, low risk of infection and fast postoperative recovery. However, due to the use of image-guided technology during minimally invasive surgery, medical staff are exposed to radiation, which affects the life and health of medical staff. In order to solve the above problems, robot-assisted minimally invasive surgery is usually used to achieve remote and automated minimally invasive surgery, thereby reducing the risk of potential harm to medical staff.

[0044] When performing surgery with a robot, medical staff cannot directly receive tactile feedback because they cannot touch the patient, which reduces the accuracy and safety of the surgery. Therefore, it is necessary to provide a highly accurate and sensitive tactile feedback mechanism for minimally invasive surgery to ensure the normal progress of the surgery.

[0045] In the related technology, commonly used tactile feedback mechanisms include different types of force sensors, such as piezoresistive sensors, capacitive sensors and fiber optic sensors. Among them, fiber optic sensors are the main research direction of force sensors due to their advantages such as system compatibility and high measurement accuracy. In actual situations, fiber optic sensors are sensitive to temperature changes, and the measurement results are greatly affected by temperature changes.

[0046] Commonly used methods for temperature compensation include reference fiber Bragg grating method and symmetric temperature compensation method. The reference fiber Bragg grating method is to set a reference fiber with a reference fiber Bragg grating in the force sensor for temperature compensation. However, the reference fiber has the disadvantages of insufficient stability and susceptibility to environmental interference, and there is a risk of fiber breakage, which greatly affects the reliability and service life of the force sensor. The symmetric temperature compensation method sets a larger number of sensing fibers in the force sensor, resulting in an increased complexity of the force sensor, which limits the miniaturization and integrated application of the force sensor.

[0047] Based on the above problems, the present application provides a force sensor, an auxiliary system based on the force sensor, and a method for measuring the loading force. The force sensor includes a birefringent optical fiber with a first fiber grating and a second fiber grating arranged in the direction of light propagation, and the first fiber grating and the second fiber grating have different central wavelengths; when the birefringent optical fiber is subjected to a loading force, the first fiber grating and the second fiber grating are used to measure the strain and temperature change of the birefringent optical fiber. The method includes: obtaining the wavelength offset of the first fiber grating and the second fiber grating through the force sensor; determining the strain and temperature change of the birefringent optical fiber according to the wavelength offset; performing stress calculation and temperature compensation according to the strain and temperature change to obtain the loading force.

[0048] The force sensor proposed in the present application uses a birefringent optical fiber with a first fiber grating and a second fiber grating for loading force sensing, and obtains the wavelength offset of the first fiber grating and the second fiber grating according to the central wavelength of each fiber grating and the birefringence property of the birefringent optical fiber, thereby obtaining the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force on the birefringent optical fiber. The present application uses multiple wavelength offsets as the data basis, and measures the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force, thereby reducing the influence of the temperature change on the calculation result of the loading force and improving the accuracy of the tactile feedback result.

[0049] In addition, compared with the technical solution in the related art of setting a reference optical fiber to eliminate the influence of temperature changes, the present application realizes tactile feedback with temperature compensation through a single optical fiber, improves the stability and integration of the force sensor, and enables the force sensor and the auxiliary system based on the force sensor to be further miniaturized, providing strong technical support for the development of robot-assisted surgery technology.

[0050] The loading force measurement method proposed in the embodiment of the present application uses the wavelength shift of the first fiber grating and the second fiber grating to perform wavelength demodulation to obtain the strain and temperature change of the birefringent optical fiber, calculates the strain according to the strain, and performs temperature compensation on the strain calculation result according to the temperature change to obtain the loading force on the birefringent optical fiber. The present application uses the force sensor in the above embodiment to measure the strain and temperature change of the birefringent optical fiber at the same time, and automatically performs temperature compensation on the loading force sensing result according to the temperature change, thereby reducing the influence of the temperature change on the loading force sensing result and improving the accuracy of the tactile feedback result.

[0051] The force sensor, auxiliary system based on the force sensor, and loading force measurement method provided in this specification can be applied to robot-assisted minimally invasive surgery technology to provide corresponding tactile feedback to the robot, wherein the robot may include a mechanical arm and a sensor system. It is understood that after adaptive modification, this application can also be used in precision control technologies in other fields, such as robot control and vehicle driving.

[0052] Reference Figure 1 As shown, an embodiment of the present application provides a force sensor, including a birefringent optical fiber 110, wherein the birefringent optical fiber 110 has a first fiber grating 120 and a second fiber grating 130 arranged in a light propagation direction, and the first fiber grating 120 and the second fiber grating 130 have different central wavelengths.

[0053] When the birefringent optical fiber 110 is subjected to a loading force, the first fiber grating 120 and the second fiber grating 130 are used to measure the strain and temperature change of the birefringent optical fiber 110 to calculate the magnitude of the loading force; wherein the strain and temperature change are determined based on the wavelength offset of the first fiber grating 120 and the second fiber grating 130 respectively.

[0054] Specifically, the birefringent optical fiber 110 has a birefringent property, so that the detection light injected into the birefringent optical fiber 110 is decomposed into a fast-axis detection light propagating along the fast axis of the birefringent optical fiber 110 and a slow-axis detection light propagating along the slow axis of the birefringent optical fiber 110. The fast-axis detection light and the slow-axis detection light propagate along the birefringent optical fiber 110, and when reaching the first fiber grating 120, the first fiber grating 120 partially reflects the fast-axis detection light according to its own central wavelength to obtain a first fast-axis reflected light, and partially reflects the slow-axis detection light to obtain a first slow-axis reflected light.

[0055] Similarly, the fast-axis detection light and the slow-axis detection light that are not reflected by the first fiber grating 120 continue to propagate along the birefringent fiber 110. When reaching the second fiber grating 130, the second fiber grating 130 partially reflects the fast-axis detection light and the slow-axis detection light according to its own central wavelength, thereby obtaining a second fast-axis reflected light and a second slow-axis reflected light.

[0056] Furthermore, when the force sensor is used for tactile feedback, the birefringent optical fiber 110 generates corresponding strain due to the external loading force, so that the first fast-axis reflected light and the first slow-axis reflected light obtained through the first fiber grating 120, and the second fast-axis reflected light and the second slow-axis reflected light obtained through the second fiber grating 130 respectively generate wavelength shifts corresponding to the strain amount of the birefringent optical fiber 110 according to the strain amount.

[0057] It should be noted that the strain sensitivities of the fast axis and the slow axis of the birefringent optical fiber 110 are different, and the wavelength shift is related to the central wavelength of the fiber grating, so the wavelength shifts obtained according to the first fast axis reflected light, the first slow axis reflected light, the second fast axis reflected light, and the second slow axis reflected light are different. According to the above wavelength shift, the strain amount and the temperature change amount of the birefringent optical fiber 110 can be measured simultaneously to calculate the magnitude of the loading force on the birefringent optical fiber 110, and the loading force is temperature compensated according to the temperature change amount, thereby reducing the influence of the temperature change amount on the calculation result of the loading force, and improving the accuracy of the tactile feedback result.

[0058] The present application adopts a birefringent optical fiber 110 as a force sensor, and obtains multiple wavelength shifts through the first fiber grating 120 and the second fiber grating 130 on the birefringent optical fiber 110, so as to simultaneously measure the strain and temperature change of the birefringent optical fiber 110 to calculate the magnitude of the loading force. Compared with the related art, the force sensor in the present application has the advantages of simple structure and miniaturization, and can also measure the corresponding variable and temperature change at the same time, and use the temperature change to perform temperature compensation, thereby realizing a temperature-independent force sensor, improving the accuracy and sensitivity of the tactile feedback results, and having broad application prospects in robot-assisted surgery technology. In addition, the force sensor provided in the present application can provide more abundant feedback information for the minimally invasive surgery process, thereby improving the safety of the minimally invasive surgery process and the success rate of minimally invasive surgery.

[0059] It is understandable that if it is necessary to measure the magnitude of the loading force in multiple directions, the number of fiber gratings carried by the birefringent optical fiber 110 can be adjusted according to the preset number of directions, so that a wavelength shift result matching the preset number of directions can be obtained, so as to be able to calculate the magnitude of the loading force on the birefringent optical fiber 110 in different directions, thereby expanding the scope of application of the force sensor provided in the present application.

[0060] The force sensor provided in the embodiment of the present application uses a birefringent optical fiber 110 with a first optical fiber grating 120 and a second optical fiber grating 130 for loading force sensing, and obtains the wavelength offset of each of the first optical fiber grating 120 and the second optical fiber grating 130 according to the central wavelength of each optical fiber grating and the birefringence property of the birefringent optical fiber 110, thereby obtaining the strain and temperature change of the birefringent optical fiber 110 to calculate the magnitude of the loading force on the birefringent optical fiber 110. The present application uses multiple wavelength offsets as data basis, and measures the strain and temperature change of the birefringent optical fiber 110 respectively to calculate the magnitude of the loading force, thereby reducing the influence of the temperature change on the calculation result of the loading force, and improving the accuracy of the tactile feedback result.

[0061] In addition, compared with the technical solution in the related art of setting a reference optical fiber to eliminate the influence of temperature changes, the present application realizes tactile feedback with temperature compensation through a single optical fiber, improves the stability and integration of the force sensor, and enables the force sensor and the auxiliary system based on the force sensor to be further miniaturized, providing strong technical support for the development of robot-assisted surgery technology.

[0062] As an embodiment of the present application, the birefringent optical fiber 110 includes a polarization-maintaining optical fiber.

[0063] Specifically, due to its asymmetric core structure design, the polarization-maintaining fiber has different propagation speeds in different directions when the probe light propagates inside the polarization-maintaining fiber, that is, the probe light exhibits birefringence inside the polarization-maintaining fiber. It is understandable that the force sensor provided by the present application utilizes the birefringence property of the polarization-maintaining fiber and obtains multiple wavelength shifts simultaneously using a single beam of probe light, thereby being able to measure the strain and temperature change of the polarization-maintaining fiber to calculate the magnitude of the loading force on the polarization-maintaining fiber.

[0064] Furthermore, polarization-maintaining fiber is a special fiber that can maintain the polarization state of the probe light, that is, when the probe light propagates in the polarization-maintaining fiber, the polarization state of the probe light will not change with the propagation process and external interference. Using polarization-maintaining fiber as a force sensor, the polarization state of the probe light is maintained during the process of obtaining the wavelength shift, thereby reducing the influence of the polarization effect on the wavelength shift measurement and improving the stability of the wavelength shift measurement.

[0065] As an embodiment of the present application, the force sensor further includes an optical fiber sleeve 140 , and a birefringent optical fiber 110 is passed through the optical fiber sleeve 140 , and the number of the birefringent optical fiber 110 is one.

[0066] Specifically, the optical fiber sleeve 140 can be a stainless steel tube with a hollow structure, and the internal size of the stainless steel tube matches the birefringent optical fiber 110. The optical fiber sleeve 140 is sleeved outside the birefringent optical fiber 110, and the birefringent optical fiber 110 is passed through the optical fiber sleeve 140 to reduce the risk of bending or breaking of the birefringent optical fiber 110 during the tactile feedback process, thereby improving the service life of the force sensor.

[0067] Furthermore, the number of birefringent optical fibers 110 is one, and both ends of the birefringent optical fibers 110 can be fixed to the optical fiber sleeve 140, thereby improving the stability of the birefringent optical fibers 110, reducing the impact of external environmental vibration and other interference on tactile feedback, and thus improving the accuracy of tactile feedback results. In addition, the force sensor provided by the present application only uses a single birefringent optical fiber, which reduces the complexity of the force sensor and provides a structural basis for the miniaturization of the force sensor and the auxiliary system based on the force sensor.

[0068] Reference Figure 2As shown, an embodiment of the present application provides an auxiliary system based on a force sensor, including a force sensor as described in any one of the above embodiments.

[0069] As an embodiment of the present application, the auxiliary system further includes a broadband light source 210 and a polarization controller 220:

[0070] The wavelength range of the broadband light source 210 covers the central wavelengths of the first fiber grating and the second fiber grating.

[0071] The polarization controller 220 is used to perform polarization modulation on the light emitted by the broadband light source 210 and output target polarized light for transmission to the birefringent optical fiber 240 .

[0072] Specifically, the broadband light source 210 (Amplified Spontaneous Emission, ASE) is a light source that can emit a light beam in a wide wavelength range, and its wavelength range can cover multiple bands. In the present application, the birefringent optical fiber 240 has a first fiber grating and a second fiber grating with different central wavelengths. In order to obtain the reflected light of the above fiber grating, the wavelength range of the detection light needs to correspond to the central wavelength of the first fiber grating and the second fiber grating. Therefore, the wavelength range of the broadband light source 210 needs to be able to cover the central wavelength of the first fiber grating and the second fiber grating.

[0073] Furthermore, the polarization controller 220 (Polarization Controller, PC) is used to perform polarization modulation on the light emitted by the broadband light source 210, so that the detection light has a preset polarization state and obtains the target polarized light. The polarization controller 220 performs polarization modulation, so that the polarization state of the light transmitted to the birefringent optical fiber 240 is controllable, thereby improving the stability of the obtained wavelength shift and the signal quality, thereby improving the accuracy of the tactile feedback result.

[0074] As an embodiment of the present application, the auxiliary system further includes a circulator 230 and a spectrometer 250:

[0075] The circulator 230 is used to transmit the target polarized light to the birefringent optical fiber 240 , and transmit the first reflected light of the first fiber grating to the target polarized light and the second reflected light of the second fiber grating to the spectrometer 250 .

[0076] The spectrometer 250 is used to determine the wavelength shift of the first fiber grating and the second fiber grating.

[0077] Specifically, the circulator 230 is an optical element that controls the direction of light transmission, so that light can be transmitted in a specific direction to avoid interference from reverse transmission. The first port of the circulator 230 is connected to the output end of the polarization controller 220, and the second port of the circulator 230 is connected to the birefringent optical fiber 240, for transmitting the target polarized light output by the polarization controller 220 to the birefringent optical fiber 240.

[0078] It can be understood that the reflected light reflected by the first fiber grating and the second fiber grating returns to the circulator 230 from the second port and is output from the third port of the circulator 230, thereby utilizing the compact structure of the circulator 230 to further reduce the complexity of the auxiliary system and achieve miniaturization of the auxiliary system.

[0079] Furthermore, the third port of the circulator 230 is connected to the spectrometer 250 (Optical Spectrum Analyzer, OSA), and the reflected light reflected by the first fiber grating and the second fiber grating is received by the spectrometer 250 to obtain the corresponding reflection spectrum, and the above reflection spectrum is spectrally analyzed according to the respective central wavelengths of the first fiber grating and the second fiber grating to obtain the shift of the peak position in the reflection spectrum before and after the loading force, thereby determining the respective wavelength shifts of the first fiber grating and the second fiber grating.

[0080] According to an embodiment of the present application, an embodiment of a loading force measurement method is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0081] In this embodiment, a method for measuring a loading force is provided, and the loading force can be measured by the above-mentioned force sensor. Figure 3 As shown, the method includes:

[0082] S100. When the birefringent optical fiber is subjected to a loading force, the wavelength shift of the first fiber grating and the wavelength shift of the second fiber grating are obtained by using a force sensor as in any one of the above embodiments.

[0083] S200. Determine the strain amount and temperature change amount of the birefringent optical fiber according to the wavelength shifts of the first optical fiber grating and the second optical fiber grating.

[0084] S300. Perform stress calculation and temperature compensation according to the strain and temperature variation of the birefringent optical fiber to obtain a loading force.

[0085] Specifically, when the birefringent optical fiber is subjected to a loading force, a spectrum analysis is performed using the center wavelengths and reflection spectra of the first fiber grating and the second fiber grating to obtain multiple wavelength offsets of the first fiber grating and the second fiber grating. It can be understood that the multiple wavelength offsets all correspond to the magnitude of the loading force, and the strain caused by the loading force on the birefringent optical fiber is described from different aspects, so as to provide a rich data basis for the calculation of the loading force.

[0086] Furthermore, according to the relationship between wavelength shift, strain and temperature variation, the strain and temperature variation of the birefringent optical fiber are calculated according to multiple wavelength shifts to obtain the strain and temperature variation. Stress calculation is performed according to the strain of the birefringent optical fiber to obtain the initial loading force data of the birefringent optical fiber, and temperature compensation is performed on the initial loading force data according to the temperature variation of the birefringent optical fiber to obtain the actual loading force magnitude of the birefringent optical fiber.

[0087] The loading force measurement method provided in this embodiment uses the wavelength shift of the first fiber grating and the second fiber grating to perform wavelength demodulation to obtain the strain and temperature change of the birefringent optical fiber, calculates the strain according to the strain, and performs temperature compensation on the strain calculation result according to the temperature change to obtain the loading force on the birefringent optical fiber. The present application uses the force sensor in the above embodiment to measure the strain and temperature change of the birefringent optical fiber at the same time, and automatically performs temperature compensation on the loading force sensing result according to the temperature change, thereby reducing the influence of the temperature change on the loading force sensing result and improving the accuracy of the tactile feedback result.

[0088] Reference Figure 4 As shown, as an embodiment of the present application, the strain amount and temperature change amount of the birefringent optical fiber are determined according to the wavelength offset of the first fiber grating and the second fiber grating, including:

[0089] S210. Demodulate the wavelength offsets of the first fiber grating and the second fiber grating using the wavelength demodulation principle formula to obtain a set of wavelength demodulation equations related to strain and temperature change.

[0090] S220. Solve the wavelength demodulation equations simultaneously to obtain the strain and temperature change.

[0091] Specifically, the form of the wavelength demodulation principle formula is expressed according to the following formula:

[0092] Δλ B =λ B [(1-P e )ε+(α f +ξ f )ΔT]

[0093] Among them, ΔλB is the wavelength shift; ε is the strain of the birefringent fiber, ΔT is the temperature change of the birefringent fiber; α f is the thermal expansion coefficient of the birefringent fiber, ξ f is the thermo-optic coefficient of the birefringent fiber, P e is the effective elastic-optical coefficient of the birefringent fiber; B is the central wavelength, which is expressed according to the following formula:

[0094] λ B =2n eff Λ

[0095] Among them, n eff is the effective refractive index of the birefringent fiber, and Λ is the period of the fiber grating.

[0096] Further, the multiple wavelength offsets obtained by the first fiber grating and the second fiber grating are substituted into the wavelength demodulation principle formula to perform wavelength demodulation on the multiple wavelength offsets, and a wavelength demodulation equation group about strain variables and temperature changes is obtained. It can be understood that the number of equations in the wavelength adjustment equation group is related to the number of strain variables that need to be solved. The wavelength demodulation equation group is solved simultaneously to obtain the corresponding strain variables and temperature changes.

[0097] Reference Figure 5 As shown, as an embodiment of the present application, obtaining the wavelength shift of the first fiber grating and the second fiber grating respectively includes:

[0098] S110. Obtain a first reflection spectrum of the first fiber grating and a second reflection spectrum of the second fiber grating; wherein the first reflection spectrum includes a first fast axis reflection spectrum and a first slow axis reflection spectrum, and the second reflection spectrum includes a second fast axis reflection spectrum and a second slow axis reflection spectrum.

[0099] S120. Perform spectral shift analysis on the first fast-axis reflection spectrum and the first slow-axis reflection spectrum to obtain a first wavelength shift and a second wavelength shift of the first fiber grating.

[0100] S130. Perform spectral shift analysis on the second fast-axis reflection spectrum and the second slow-axis reflection spectrum to obtain a third wavelength shift and a fourth wavelength shift of the second fiber grating.

[0101] Specifically, a spectrometer is used to obtain a first fast axis reflection spectrum according to the first fast axis reflection light, a first slow axis reflection spectrum according to the first slow axis reflection light, a second fast axis reflection spectrum according to the second fast axis reflection light, and a second slow axis reflection spectrum according to the second slow axis reflection light.

[0102] Furthermore, when the birefringent optical fiber is subjected to a loading force, the birefringent optical fiber generates corresponding strain due to the loading force, so that the peak positions in the first fast-axis reflection spectrum, the first slow-axis reflection spectrum, the second fast-axis reflection spectrum, and the second slow-axis reflection spectrum are shifted. Based on the above reflection spectra and the respective central wavelengths of the first fiber grating and the second fiber grating, a spectrum shift analysis is performed to obtain the shift of the peak position in the reflection spectrum before and after the loading force is applied, thereby determining the wavelength shift of the first fiber grating and the second fiber grating.

[0103] Among them, the first wavelength shift can be obtained by performing wavelength shift analysis based on the first central wavelength and the first fast axis reflection spectrum; the second wavelength shift can be obtained by performing wavelength shift analysis based on the first central wavelength and the first slow axis reflection spectrum. The third wavelength shift can be obtained by performing wavelength shift analysis based on the second central wavelength and the second fast axis reflection spectrum; the fourth wavelength shift can be obtained by performing wavelength shift analysis based on the second central wavelength and the second slow axis reflection spectrum.

[0104] Reference Figure 6 As shown, as an embodiment of the present application, the strain includes three-dimensional strain; the strain and temperature change of the birefringent optical fiber are determined according to the wavelength offset of the first fiber grating and the second fiber grating, including:

[0105] S230. Construct four demodulation equations about three-dimensional strain and temperature variation according to the first wavelength shift, the second wavelength shift, the third wavelength shift and the fourth wavelength shift.

[0106] S240. Solve the four demodulated equations simultaneously to obtain three-dimensional strain and temperature change.

[0107] Specifically, the center wavelengths of the first fiber grating and the second fiber grating are different, so that the fiber response coefficients corresponding to the first wavelength shift and the second wavelength shift are different from the third wavelength shift and the fourth wavelength shift, so that the wavelength shift degrees of the reflection spectra of the first fiber grating and the second fiber grating are different when the birefringent fiber generates strain. Similarly, the optical properties of the birefringent fiber on the fast axis and the slow axis are different, so that the wavelength shift degrees of the fast axis reflection spectrum and the slow axis reflection spectrum are different. Therefore, according to the first wavelength shift, the second wavelength shift, the third wavelength shift and the fourth wavelength shift and the fiber response coefficients corresponding to the above wavelength shifts, four demodulation equations about three-dimensional strain and temperature change can be constructed.

[0108] Furthermore, the above four demodulation equations are solved simultaneously to obtain the three-dimensional strain and temperature variation of the birefringent optical fiber, wherein the three-dimensional strain may include the strain of the birefringent optical fiber in three different directions. The stress is calculated according to the three-dimensional strain, and its form is expressed according to the following formula:

[0109]

[0110] Among them, F is the loading force on the birefringent fiber; A is the cross-sectional area of ​​the birefringent fiber, and E is the elastic modulus of the birefringent fiber. The initial loading force data on the birefringent fiber is calculated according to the above formula, and the initial loading force data is automatically temperature compensated according to the temperature change, thereby reducing the influence of the temperature change on the loading force sensing result, and the actual loading force on the birefringent fiber is obtained as the tactile feedback result.

[0111] Accordingly, please refer to Figure 7 , an embodiment of the present application provides a loading force measuring device, the device comprising:

[0112] The wavelength shift acquisition module 310 is used to acquire the wavelength shift of the first fiber grating and the second fiber grating respectively by using a force sensor as in any one of the above embodiments when the birefringent optical fiber is subjected to a loading force.

[0113] The optical fiber parameter determination module 320 is used to determine the strain and temperature variation of the birefringent optical fiber according to the wavelength shifts of the first optical fiber grating and the second optical fiber grating.

[0114] The loading force calculation module 330 is used to perform stress calculation and temperature compensation according to the strain and temperature variation of the birefringent optical fiber to obtain the loading force.

[0115] In some optional implementations, the optical fiber parameter determination module 320 includes:

[0116] The wavelength demodulation unit is used to perform wavelength demodulation on the wavelength deviation of the first fiber grating and the second fiber grating respectively by using the wavelength demodulation principle formula to obtain a set of wavelength demodulation equations about strain and temperature change.

[0117] The simultaneous solving unit is used to simultaneously solve the wavelength demodulation equations to obtain the strain and temperature change.

[0118] In some optional implementations, the wavelength shift acquisition module 310 includes:

[0119] The spectrum acquisition unit is used to acquire a first reflection spectrum of the first fiber grating and a second reflection spectrum of the second fiber grating; wherein the first reflection spectrum includes a first fast axis reflection spectrum and a first slow axis reflection spectrum, and the second reflection spectrum includes a second fast axis reflection spectrum and a second slow axis reflection spectrum.

[0120] The first shift analysis unit is used to perform spectrum shift analysis on the first fast-axis reflection spectrum and the first slow-axis reflection spectrum to obtain a first wavelength shift and a second wavelength shift of the first fiber grating.

[0121] The second shift analysis unit is used to perform spectrum shift analysis on the second fast axis reflection spectrum and the second slow axis reflection spectrum to obtain the third wavelength shift and the fourth wavelength shift of the second fiber grating.

[0122] In some optional embodiments, the strain includes three-dimensional strain; the optical fiber parameter determination module 320 further includes:

[0123] The three-dimensional equation construction unit is used to construct four demodulation equations about three-dimensional strain and temperature variation according to the first wavelength shift, the second wavelength shift, the third wavelength shift and the fourth wavelength shift.

[0124] The three-dimensional simultaneous solution unit is used to solve the four demodulation equations simultaneously to obtain the three-dimensional strain and temperature change.

[0125] The further functional description of each of the above modules and units is the same as that of the above corresponding embodiments and will not be repeated here.

[0126] The load force measuring device in this embodiment is presented in the form of a functional unit, where the unit refers to an ASIC (Application Specific Integrated Circuit) circuit, a processor and memory that executes one or more software or fixed programs, and / or other devices that can provide the above functions.

[0127] See also Figure 8 , Figure 8 It is a structural diagram of a computer device provided by an embodiment of the present application. As shown in the figure, the computer device includes: one or more processors 10, a memory 20, and an interface for connecting various components, including a high-speed interface and a low-speed interface. Each component uses different buses to communicate with each other, and can be installed on a common motherboard or installed in other ways as needed. The processor can process instructions executed in the computer device, including instructions stored in or on the memory to display the graphical information of the GUI on an external input / output device (such as a display device coupled to the interface). In some optional embodiments, if necessary, multiple processors and / or multiple buses can be used together with multiple memories and multiple memories. Similarly, multiple computer devices can be connected, and each device provides some necessary operations (for example, as a server array, a group of blade servers, or a multi-processor system). Figure 8 A processor 10 is taken as an example.

[0128] The processor 10 may be a central processing unit, a network processor or a combination thereof. The processor 10 may further include a hardware chip. The hardware chip may be a dedicated integrated circuit, a programmable logic device or a combination thereof. The programmable logic device may be a complex programmable logic device, a field programmable gate array, a general purpose array logic or any combination thereof.

[0129] The memory 20 stores instructions executable by at least one processor 10, so that the at least one processor 10 executes the method shown in the above embodiment.

[0130] The memory 20 may include a program storage area and a data storage area, wherein the program storage area may store an operating system, an application required for at least one function; the data storage area may store data created according to the use of the computer device, etc. In addition, the memory 20 may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some optional embodiments, the memory 20 may optionally include a memory remotely arranged relative to the processor 10, and these remote memories may be connected to the computer device via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0131] The memory 20 may include a volatile memory, such as a random access memory; the memory may also include a non-volatile memory, such as a flash memory, a hard disk or a solid state drive; the memory 20 may also include a combination of the above types of memory.

[0132] The computer device further comprises a communication interface 30 for the computer device to communicate with other devices or a communication network.

[0133] The embodiment of the present application also provides a computer-readable storage medium. The above method according to the embodiment of the present application can be implemented in hardware, firmware, or can be implemented as a computer code that can be recorded in a storage medium, or can be implemented as a computer code that is originally stored in a remote storage medium or a non-temporary machine-readable storage medium and will be stored in a local storage medium through a network download, so that the method described herein can be stored in such software processing on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only storage memory, a random access memory, a flash memory, a hard disk or a solid-state hard disk, etc.; further, the storage medium can also include a combination of the above types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by a computer, a processor, or hardware, the method shown in the above embodiment is implemented.

[0134] The systems, devices, modules or units described in the above embodiments may be implemented by computer chips or entities, or by products with certain functions. A typical implementation device is a computer. Specifically, the computer may be, for example, a personal computer, a laptop computer, a cellular phone, a camera phone, a smart phone, a personal digital assistant, a media player, a navigation device, an email device, a game console, a tablet computer, a wearable device, or a combination of any of these devices.

[0135] For the convenience of description, the above device is described in various units according to their functions. Of course, when implementing the present application, the functions of each unit can be implemented in the same or multiple software and / or hardware.

[0136] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0137] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0138] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0139] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0140] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0141] Each embodiment in this specification is described in a progressive manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0142] The above is only an embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the claims of the present application.

[0143] Although the embodiments of the present application have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A force sensor, characterized in that: The birefringent optical fiber comprises a first optical fiber grating and a second optical fiber grating arranged in a light propagation direction, wherein the first optical fiber grating and the second optical fiber grating have different central wavelengths; When the birefringent optical fiber is subjected to a loading force, the first optical fiber Bragg grating and the second optical fiber Bragg grating are used to measure the strain and temperature change of the birefringent optical fiber to calculate the magnitude of the loading force; wherein the strain and the temperature change are determined based on the wavelength offset of the first optical fiber Bragg grating and the second optical fiber Bragg grating, respectively.

2. The force sensor according to claim 1, characterized in that The birefringent optical fiber includes a polarization-maintaining optical fiber.

3. The force sensor according to claim 1, characterized in that The force sensor further comprises an optical fiber sleeve, wherein the birefringent optical fiber is passed through the optical fiber sleeve, and the number of the birefringent optical fiber is one.

4. An auxiliary system based on a force sensor, characterized in that: Comprising the force sensor as claimed in any one of claims 1 to 3.

5. The auxiliary system according to claim 4, characterized in that: The auxiliary system also includes a broadband light source and a polarization controller; The wavelength range of the broadband light source covers the central wavelengths of the first fiber grating and the second fiber grating; The polarization controller is used to perform polarization modulation on the light emitted by the broadband light source and output target polarized light for transmission to the birefringent optical fiber.

6. The auxiliary system according to claim 5, characterized in that: The auxiliary system also includes a circulator and a spectrometer: The circulator is used to transmit the target polarized light to the birefringent optical fiber, and transmit the first reflected light of the target polarized light by the first optical fiber grating and the second reflected light of the target polarized light by the second optical fiber grating to the spectrometer; The spectrometer is used to determine the wavelength shift of the first fiber grating and the second fiber grating respectively.

7. A method for measuring loading force, characterized in that: The method comprises: When the birefringent optical fiber is subjected to a loading force, obtaining the wavelength shift of each of the first fiber grating and the second fiber grating by using the force sensor according to any one of claims 1 to 3; Determining the strain and temperature variation of the birefringent optical fiber according to the wavelength shifts of the first optical fiber grating and the second optical fiber grating; The loading force is obtained by performing stress calculation and temperature compensation according to the strain and temperature variation of the birefringent optical fiber.

8. The method according to claim 7, characterized in that The step of determining the strain and temperature variation of the birefringent optical fiber according to the wavelength shift of the first optical fiber grating and the second optical fiber grating comprises: Demodulating the wavelength offsets of the first fiber grating and the second fiber grating by using a wavelength demodulation principle formula to obtain a set of wavelength demodulation equations related to the strain and the temperature change; The wavelength demodulation equations are solved simultaneously to obtain the strain and the temperature change.

9. The method according to claim 7, characterized in that: The obtaining of the wavelength shift of the first fiber grating and the second fiber grating comprises: Acquire a first reflection spectrum of the first fiber grating and a second reflection spectrum of the second fiber grating; wherein the first reflection spectrum includes a first fast-axis reflection spectrum and a first slow-axis reflection spectrum, and the second reflection spectrum includes a second fast-axis reflection spectrum and a second slow-axis reflection spectrum; Performing spectral shift analysis on the first fast-axis reflection spectrum and the first slow-axis reflection spectrum to obtain a first wavelength shift and a second wavelength shift of the first fiber grating; A spectrum shift analysis is performed on the second fast-axis reflection spectrum and the second slow-axis reflection spectrum to obtain a third wavelength shift and a fourth wavelength shift of the second fiber grating.

10. The method according to claim 9, characterized in that The strain includes three-dimensional strain; and determining the strain and temperature variation of the birefringent optical fiber according to the wavelength shift of each of the first optical fiber grating and the second optical fiber grating, including: constructing four demodulation equations about the three-dimensional strain and the temperature variation according to the first wavelength shift, the second wavelength shift, the third wavelength shift and the fourth wavelength shift; The four demodulation equations are solved simultaneously to obtain the three-dimensional strain and the temperature change.

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