Distributed optical fiber spatial pose sensor and spatial pose measurement method and system based on same

Abstract

The invention relates to the technical field of optical fiber sensing, in particular to a distributed optical fiber space pose sensor and a space pose measuring method and system based on the distributed optical fiber space pose sensor, and the sensor comprises a bottom lining which is made of nickel-titanium alloy wires and has torsion resistance and superelasticity; a plurality of V-shaped grooves are engraved in the surface of the bottom lining along the axial direction of the bottom lining and are symmetrically distributed along the circumference of the bottom lining; and the plurality of sensing optical fibers correspond to the plurality of V-shaped grooves and are respectively fixed in the corresponding V-shaped grooves. The system comprises the distributed optical fiber space pose sensor. The strain measurement module is used for measuring strain information generated by deformation of the distributed optical fiber space pose sensor; and the reconstruction device is used for calculating and reconstructing the spatial pose of the distributed optical fiber spatial pose sensor according to the strain information. The problems that an existing spatial pose sensor is prone to torsion and low in reconstruction precision are solved, and the spatial pose sensor has the advantages of being high in geometric stability and large in fiber core distance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical fiber sensing, in particular to a distributed optical fiber spatial pose sensor and a spatial pose measurement method and system based thereon. BACKGROUND

[0002] Spatial pose sensing technology is to obtain the position and attitude of an object in three-dimensional space in real time, and to provide core spatial data support for robot navigation, aviation, medical surgery and other scenarios. In clinical diagnosis and treatment, especially in minimally invasive interventional surgery, surgeons place a guide wire through a small incision on the body surface to establish a channel, and then introduce a catheter instrument along the guide wire to implement precise operation. High-precision guide wire dynamic tracking technology can display the spatial pose in real time, helping doctors quickly and accurately find the lesion area, improving treatment efficiency and reducing clinical burden. Minimally invasive interventional surgery requires accurate information of the guide wire relative to the target position, so the dynamic spatial pose display technology of the catheter / guide wire has important research significance and application value.

[0003] At present, many catheter / guide wire tracking methods have been proposed. Traditional methods such as MRI navigation, electromagnetic navigation, ultrasonic navigation, and X-ray fluoroscopy are widely used in clinical diagnosis and treatment. MRI navigation is to realize guide wire navigation by combining magnetic field compatible guide wire with real-time image feedback; electromagnetic navigation is to capture the guide wire tip position by using electromagnetic sensing for single-point positioning; ultrasonic navigation uses ultrasonic echo ranging and imaging; X-ray fluoroscopy is to form a clear image of the shape of the blood vessels by injecting contrast medium to enhance the difference in X-ray absorption between blood vessels and surrounding tissues. These catheter / guide wire tracking methods are easily disturbed by electromagnetic and metal instruments, and are not conducive to the integration of guide wires. As a newly proposed method, optical fiber spatial pose sensing technology has more obvious practical advantages than traditional methods, such as: optical fiber sensing has the characteristics of continuity, real-time, immunity to electromagnetic interference, etc., can reconstruct the spatial pose of the catheter throughout the process; no X-ray or contrast agent is needed to avoid radiation exposure of doctors and patients; small size (diameter between 100 µm and 2 mm) allows optical fiber to be integrated into microcatheters; and monitoring can be performed through a remote detection unit. However, the existing optical fiber spatial pose sensing technology has insufficient reconstruction accuracy. In order to improve the reconstruction accuracy of optical fiber spatial pose sensing technology, researchers have conducted research on sensors, strain measurement systems and reconstruction algorithms.

[0004] In the aspect of sensor development, the schemes adopted by the spatial pose reconstruction technology based on distributed fiber sensing include multi-fiber integration and spiral multi-core fiber. The multi-fiber integration scheme is to construct a sensing array by bonding multiple independent optical fibers, and to realize the reconstruction of the spatial pose of the optical fiber by measuring the curvature and the angle of the bend. This method can increase the curvature sensitivity by increasing the fiber core distance, but has problems such as poor consistency of the relative positions between the multiple optical fibers, and insufficient long-term stability. The spiral multi-core fiber scheme produces a spiral structure during fiber drawing, and has the advantages of good physical consistency between the fiber cores and uniform curvature sensitivity compared with multiple optical fibers, but has the problems of small fiber core spacing and low curvature sensitivity, resulting in large spatial pose reconstruction error. At the same time, this scheme requires expensive fan-in and fan-out devices, increasing the cost and production complexity.

[0005] Strain measurement technology is divided into point sensor measurement and distributed sensor measurement. Point sensor measurement mainly uses fiber Bragg grating (FBG), which is widely used in optical fiber spatial pose sensing, but FBG has a measurement blind zone when measuring strain, which will cause reconstruction error when there is a change in spatial pose in the blind zone; distributed fiber sensing technology mainly includes optical frequency domain reflectometer (OFDR) based on Rayleigh scattering principle and Brillouin optical time domain reflectometer (BOTDA) based on Brillouin scattering principle, OFDR has high spatial resolution and high strain measurement accuracy, BOTDA has a larger measurement range and low strain measurement accuracy.

[0006] In the aspect of reconstruction algorithm, the spatial pose reconstruction technology mainly adopts Frenet frame and Bishop frame algorithm. Frenet frame describes the local geometric characteristics of a spatial curve through curvature and torsion, is mathematically rigorous, and is suitable for continuous curve reconstruction. However, when there are singular points in the local curve, it is difficult for Frenet frame to determine the direction of the curve, resulting in incorrect solution. In contrast, the Bishop frame adopts parallel algorithm, directly updates the local coordinate system through curvature and bending direction angle, without calculating torsion, avoiding singular point problem.

[0007] However, fiber optic spatial pose reconstruction technology, including fiber optic spatial pose sensors, strain measurement systems, and reconstruction algorithms, all affect reconstruction accuracy. Existing fiber optic spatial pose sensors suffer from problems such as sensor torsion and small core spacing. Fiber torsion alters the geometric distribution of the spatial pose sensor, causing inaccuracies in the traditional fiber bending-strain model and significantly reducing spatial pose reconstruction accuracy. Small core spacing reduces strain resolution and curvature measurement sensitivity, further lowering spatial pose reconstruction accuracy. In strain measurement systems, while fiber Bragg gratings (FBGs) offer high strain sensitivity, their measurement blind zone reduces reconstruction accuracy. OFDRs, despite high spatial resolution and strain accuracy, have a small measurement range. Traditional BOTDAs, while having a large measurement range, suffer from poor strain accuracy.

[0008] In summary, how to invent a distributed fiber optic spatial pose sensor with anti-torsion and high spatial pose reconstruction accuracy is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] Therefore, it is necessary to address the problems of existing spatial pose sensors being prone to twisting and having small fiber core pitch by providing a distributed optical fiber spatial pose sensor and a spatial pose measurement method and system based on it, which has the characteristics of high stability and high reconstruction accuracy.

[0010] To achieve the above-mentioned objectives of this invention, the technical solution adopted is as follows: A torsion-resistant distributed fiber optic spatial pose sensor, comprising: A base liner made of nickel-titanium alloy wire; the surface of the base liner is engraved with a plurality of V-shaped grooves along its axial direction, the plurality of V-shaped grooves being symmetrically distributed along the circumference of the base liner; Several sensing optical fibers, each corresponding to a V-groove, are fixed in their respective V-grooves.

[0011] Preferably, specifically, there are 3 V-grooves and 3 sensing fibers, and the 3 V-grooves are distributed at 120° intervals. The sensing fibers are fixed in different V-grooves with glue, wherein the sensing fibers are high Brillouin gain dispersion fibers.

[0012] Furthermore, it also includes a stainless steel tube with an outer diameter larger than the nickel-titanium alloy wire, which is sleeved on the outside to assist the sensing optical fiber; it is fixed with glue to fit tightly into the V-groove.

[0013] A three-dimensional spatial pose measurement system, comprising: The aforementioned distributed fiber optic spatial pose sensor; The strain measurement module is optically connected to the sensing fiber of the sensor and is used to measure the strain information generated by the deformation of the distributed fiber spatial pose sensor. The reconstruction device is electrically connected to the strain measurement module and is used to calculate and reconstruct the spatial pose of the distributed fiber optic spatial pose sensor based on the strain information.

[0014] Furthermore, the strain measurement module is a Brillouin optical time-domain reflectometer (BOTDA) based on differential pulse pair technology; the reconstruction device uses the Bishop framework algorithm to realize spatial pose reconstruction.

[0015] Furthermore, the strain measurement module includes a laser source, a coupler, a first polarization controller, a second polarization controller, a first electro-optic modulator, a second electro-optic modulator, a first signal generator, a second signal generator, a third signal generator, a polarization scrambler, an optical isolator, a pulse modulator, an optical amplifier, a sensing fiber, a first circulator, a second circulator, a grating, a photodetector, and an oscilloscope. The laser source output is connected to the coupler input, and the coupler output is connected to the inputs of the two polarization controllers. The polarization controller outputs are connected to the inputs of the two electro-optic modulators. The output channel of the first signal generator is connected to the RF input of the first electro-optic modulator and the port of the oscilloscope. The output of the first electro-optic modulator is connected to the polarization scrambler input. The output of the second signal generator is connected to the RF input of the second electro-optic modulator. The output of the second electro-optic modulator is connected to the input of the optical isolator. The polarization scrambler output is connected to the input of the optical amplifier. The output of the optical amplifier is connected to the input of the pulse modulator. The output of the third signal generator is connected to the RF port of the pulse modulator. The output of the optical isolator is connected to the input of the sensing fiber. The outputs of the pulse modulator and the sensing fiber are connected to the port of the first circulator. The output of the first circulator is connected to the input of the second circulator. The output of the second circulator is connected to the grating input and the photodetector input. The photodetector output is connected to the oscilloscope input.

[0016] A method for measuring three-dimensional spatial pose, employing the aforementioned three-dimensional spatial pose measurement system, includes the following steps: The strain measurement module measures the distributed Brillouin frequency shift of all sensing fibers in the distributed fiber optic spatial pose sensor. and obtain distributed strain information. ; The reconstruction device receives the distributed strain information. And convert it into the curvature of each point along the sensor line. and bending direction angle Based on the Bishop framework algorithm, utilizing the curvature and bending direction angle The three-dimensional spatial pose of the distributed fiber optic spatial pose sensor is reconstructed.

[0017] Preferably, the reconstruction device further includes a calibration step before reconstruction: placing the distributed fiber optic spatial pose sensor in a calibration mold and measuring its first... The change in Brillouin frequency shift of each optical fiber The curvature coefficient at each location is calculated through linear fitting. And according to the formula Calculate and determine optical fiber Distribution of fiber core spacing .

[0018] Furthermore, the distributed Brillouin frequency shift variation of all sensing fibers in the distributed fiber optic spatial pose sensor is measured. and obtain distributed strain information. The specific steps are as follows: The strain measurement module generates pump light and probe light respectively and injects them into both ends of all sensing fibers in the distributed fiber optic spatial pose sensor. The pump light is modulated by a double pulse, and the probe light is modulated by a double-sideband modulation with a suppressed carrier. Stimulated Brillouin scattering occurs through the modulated pump light and probe light; The amplified probe light is detected to acquire Brillouin time-domain signals; The distributed Brillouin frequency shift was obtained by probing the optical frequency using step scanning and performing Lorentz fitting on the Brillouin gain spectrum. ; Based on the relationship between Brillouin frequency shift and strain and temperature Calculation to obtain distributed strain information ,in It is the change in temperature. and These are the temperature and strain coefficient of the optical fiber, respectively.

[0019] Furthermore, the specific steps for reconstructing the three-dimensional spatial pose of the distributed fiber optic spatial pose sensor are as follows: In the preset coordinate system, according to the strain-curvature transformation formula Solve for the curvature on the optical fiber of the distributed optical fiber spatial pose sensor. and bending direction angle ;in For optical fiber The change in strain. For optical fiber fiber core pitch, For optical fiber The preset angle with the x-axis of the coordinate system; Substitute the desired curvature and bending direction angle into the Bishop frame:

[0020] in, for The tangent vector at the point pointing in the direction of curvature. and Curvature Based on the bending direction angle of mutually perpendicular unit vectors and The projection in the direction, and and Commonly perpendicular to direction; By tangent vector Points The three-dimensional shape of the sensor is reconstructed. , This is the initial position vector.

[0021] The beneficial effects of this invention are as follows: The fiber optic spatial pose sensor fabrication method designed in this invention is a multi-fiber sensor fabrication method based on nickel-titanium alloy. This method not only achieves anti-torsion function and improves the accuracy of spatial pose reconstruction, but also enhances the accuracy of curvature measurement and bending angle measurement by increasing the fiber core pitch, thereby improving the accuracy of spatial pose reconstruction. Furthermore, the method of engraving V-grooves on the nickel-titanium alloy can further increase the fiber core pitch, improve the accuracy of curvature measurement and bending angle measurement, and simultaneously improve the spatial consistency and stability of the multiple fibers. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a torsion-resistant distributed fiber optic spatial pose sensor in Example 1. Figure 2 This is a schematic diagram of a three-dimensional spatial pose measurement system in Example 2; Figure 3 This is a schematic diagram of the strain measurement method described in Example 2; Figure 4 This is a cross-sectional view of the spatial pose sensor in Example 3; Figure 5 This is a schematic diagram of the three-dimensional spatial pose reconstruction result in Example 3.

[0023] Among them, 1 is a distributed optical fiber spatial pose sensor, 2 is a strain measurement module, 3 is a reconstruction device, 4 is a V-groove, 5 is a substrate, 6 is a sensing optical fiber, 7 is a stainless steel tube, 201 is a laser source, 202 is a coupler, 203 is a first polarization controller, 204 is a second polarization controller, 205 is a first electro-optic modulator, 206 is a second electro-optic modulator, 207 is a first signal generator, 208 is a polarization scrambler, 209 is an optical isolator, 210 is an optical amplifier, 211 is a pulse modulator, 213 is a first circulator, 214 is a second circulator, 215 is a grating, 216 is a photodetector, and 217 is an oscilloscope. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0025] Example 1 like Figure 1 As shown, a torsion-resistant distributed fiber optic spatial pose sensor 1 includes: The liner is made of nickel-titanium alloy wire and has torsion resistance and super elasticity; the surface of the liner 5 is engraved with a number of V-shaped grooves along its axial direction, and the number of V-shaped grooves are symmetrically distributed along the circumference of the liner 5. Several sensing optical fibers 6 are fixed in their respective V-grooves.

[0026] In one specific embodiment, specifically, there are 3 V-grooves and 3 sensing optical fibers 6, and the 3 V-grooves are distributed at 120° intervals. The sensing optical fibers are fixed in different V-grooves with glue, wherein the sensing optical fibers 6 are high Brillouin gain dispersion optical fibers.

[0027] In one specific embodiment, a stainless steel tube 7 with an outer diameter larger than the nickel-titanium alloy wire is also included, which is sleeved on the outside to assist the sensing optical fiber 6; it is fixed with glue to fit tightly into the V-groove.

[0028] In this embodiment, it is worth noting that the nickel-titanium alloy wire backing 5 increases the core pitch between the three optical fibers. A larger core pitch can improve the curvature measurement sensitivity and the spatial pose reconstruction accuracy. The V-groove 4 design can further expand the core pitch and improve curvature sensitivity. In addition, it can prevent the sensing optical fiber 6 from moving easily, and the geometric structure can maintain a stable state for a long time. The diameter of the stainless steel tube is slightly larger than the outer diameter of the backing 5. This is to assist the optical fiber in entering the groove and maintaining a tight fit with the V-groove 4, which facilitates the application of glue for fixation.

[0029] Example 2 This invention proposes a torsion-resistant distributed fiber optic spatial pose sensor. Specifically, as follows... Figure 2 As shown, the scheme comprises three parts: a fiber optic spatial pose sensor, a strain measurement system, and a reconstruction device. The fiber optic spatial pose sensor 1 uses a nickel-titanium alloy wire as a substrate, with three V-grooves spaced 120 degrees apart etched on its surface. The fiber is glued into the V-grooves, firmly securing it and solving the problem of easy relative displacement of the fiber, making it less prone to geometric position changes. Furthermore, it can further increase the fiber core pitch and improve curvature sensitivity. The strain measurement system 2 employs differential pulse-pair BOTDA technology. Differential pulse-pair BOTDA technology uses two pump pulses with slightly different pulse widths. The Brillouin gain signals obtained from the two measurements are subtracted in the time domain, and the differential signal is equivalent to a... A narrow pulse response with a width equal to the difference between two pulse widths (Δτ) results in spatial resolution determined by Δτ, rather than the width of a single pulse. This differential operation achieves sub-meter spatial resolution, but the increase in spatial resolution leads to Brillouin gain spectrum broadening and signal-to-noise ratio decrease, requiring a sacrifice of some accuracy. To further improve strain measurement accuracy, this invention proposes using high Brillouin gain dispersion fiber as the sensing fiber for the spatial pose sensor. This fiber ensures that while improving spatial resolution, it also improves Brillouin gain and signal-to-noise ratio, reduces strain accuracy loss, and further improves strain measurement accuracy, thereby achieving high-precision spatial pose reconstruction. The reconstruction device 3 mainly utilizes the Bishop framework algorithm to achieve spatial pose reconstruction.

[0030] The aforementioned three-dimensional spatial pose measurement system includes: The distributed fiber optic spatial pose sensor 1; The strain measurement module 2 is optically connected to the sensing fiber 6 of the sensor 1 and is used to measure the strain information generated by the deformation of the distributed fiber optic spatial pose sensor 1. The reconstruction device 3 is electrically connected to the strain measurement module 2 and is used to calculate and reconstruct the spatial pose of the distributed fiber optic spatial pose sensor 1 based on the strain information.

[0031] In one specific embodiment, the strain measurement module 2 is a Brillouin optical time-domain reflectometer (BOTDA) based on differential pulse pair technology; the reconstruction device 3 uses the Bishop framework algorithm to realize spatial pose reconstruction.

[0032] In one specific embodiment, such as Figure 3As shown, the strain measurement module 2 includes a laser source 201, a 50:50 coupler 202, a first polarization controller 203, a second polarization controller 204, a first electro-optic modulator 205, a second electro-optic modulator 206, a first signal generator 207, a second signal generator 218, a third signal generator 219, a polarization scrambler 208, an optical isolator 209, a pulse modulator 211, an optical amplifier 210, a first circulator 213, a second circulator 214, a grating 215, a photodetector 216, and an oscilloscope 217. The output terminal 201a of the laser source 201 is connected to the input terminal 202a of the 50:50 coupler 202. The output terminal of the 50:50 coupler 202 is connected to the input terminals 203a and 204a of the two polarization controllers 203 and 204, respectively. The output terminals 203b and 204b of the polarization controllers 203 and 204 are connected to the input terminals 205a and 206a of the two electro-optic modulators 205 and 206, respectively. The output channel of the first signal generator 207... Ports 207a and 207b are respectively connected to the RF input terminal 205c of the first electro-optic modulator 205 and port 217b of the oscilloscope 217; the output terminal of the first electro-optic modulator 205 is connected to the input terminal 208a of the polarization scrambler 208; the output terminal 218a of the second signal generator 218 is connected to the RF input terminal 206c of the second electro-optic modulator 206; the output terminal 206b of the second electro-optic modulator 206 is connected to the input terminal 207b of the optical isolator 209. 9a; the output terminal 208b of the polarization scrambler 208 is connected to the input terminal 210a of the optical amplifier 210; the output terminal 210b of the optical amplifier 210 is connected to the input terminal 211a of the pulse modulator 211; the output terminal 219a of the third signal generator 219 is connected to the RF port 211c of the pulse modulator 211; the output terminal 209b of the optical isolator 209 is connected to the input terminal of the sensing fiber 6; the output terminal 211b of the pulse modulator 211 and the The output ends of the sensing fiber 6 are connected to ports 213a and 213b of the first circulator 213, respectively; the output end 213c of the first circulator 213 is connected to the input end 214a of the second circulator 214; the output ends 214b and 214c of the second circulator 214 are connected to the input end 215a of the grating 215 and the input end 216a of the photodetector 216, respectively; the output end 216b of the photodetector 216 is connected to the input end 217a of the oscilloscope 217.

[0033] The working principle of the strain measurement module 2 is as follows: The light emitted from the laser source 201 enters the pump optical path. The first signal generator 207 provides an electrical signal pulse pair to drive the first electro-optic modulator 205 to generate an optical pulse pair. After passing through the polarizer 208 and the optical amplifier 210, the third signal generator 219 drives the pulse modulator 211 to remove the DC component of the pulse to improve the extinction ratio. Finally, a pump pulse pair with a high extinction ratio is formed and injected into the sensing optical fiber 6 through the first circulator 213. The light emitted from the laser source 201 enters the detection optical path, and the second signal generator 218 provides a radio frequency electrical signal to drive the second electro-optic modulator 206 to modulate the light wave into a double-sideband suppressing the carrier. The first-order Stokes sideband differs from the pump light frequency by a Brillouin frequency shift, which serves as the detection light injected into the other end of the sensing optical fiber 6 via the optical isolator 209. The pump pulse and the probe light undergo stimulated Brillouin scattering in the sensing fiber 6. The amplified probe light is filtered out by circulators 213 and 214 and grating 215 to produce a first-order Stokes sideband. The signal is converted into an electrical signal by photodetector 216 and the Brillouin time domain signal is acquired on oscilloscope 217. The strain measurement system employs differential pulse pair (DPP) technology. It achieves high spatial resolution determined by Δτ by subtracting the Brillouin gain signals generated by two pump pulses with a slight difference in pulse width Δτ in the time domain. Furthermore, it obtains the distance-frequency mapping spectrum by scanning the frequency of the second signal generator 218, and then obtains the distributed Brillouin variation through Lorentz fitting. .

[0034] This invention designs a strain measurement system based on BOTDA technology using high-gain optical fiber, which has the advantages of large measurement range, high spatial resolution, and high strain measurement accuracy.

[0035] Example 3 A method for measuring three-dimensional spatial pose, employing the aforementioned three-dimensional spatial pose measurement system, includes the following steps: The strain measurement module 2 measures the distributed Brillouin frequency shift of all sensing fibers 6 in the distributed optical fiber spatial pose sensor 1. and obtain distributed strain information. ; The reconstruction device 3 receives the distributed strain information. And convert it into the curvature of each point along the line of sensor 1. and bending direction angle Based on the Bishop framework algorithm, utilizing the curvature and bending direction angle The three-dimensional spatial pose of the distributed fiber optic spatial pose sensor 1 is reconstructed.

[0036] In one specific embodiment, the distributed Brillouin frequency shift variation of all sensing fibers 6 in the distributed fiber spatial pose sensor 1 is measured. and obtain distributed strain information. The specific steps are as follows: The strain measurement module 2 generates pump light and probe light respectively and injects them into both ends of all sensing optical fibers 6 in the distributed optical fiber spatial pose sensor 1. The pump light is modulated by a double pulse, and the probe light is modulated by a double-sideband modulation with a suppressed carrier. Stimulated Brillouin scattering occurs through the modulated pump light and probe light; The amplified probe light is detected to acquire Brillouin time-domain signals; The distributed Brillouin frequency shift was obtained by probing the optical frequency using step scanning and performing Lorentz fitting on the Brillouin gain spectrum. ; Based on the relationship between Brillouin frequency shift and strain and temperature Calculation to obtain distributed strain information ,in It is the change in temperature. and These are the temperature and strain coefficient of the optical fiber, respectively.

[0037] The cross-sections of the three optical fibers used in this embodiment are as follows: Figure 4 As shown, this illustrates the principle of spatial pose sensing. Specifically, when the optical fiber deforms, the three optical fibers generate corresponding bending strain signals. The strain is converted into curvature and bending direction angle by utilizing the relationship between bending strain, curvature, and bending direction angle.

[0038] In one specific embodiment, before the reconstruction device 3 performs reconstruction, a calibration step is also included: when the entire sensor is in a flat state, the Brillouin frequency shift change data is measured using a Brillouin time-domain reflectometer as a reference group signal; the spatial pose sensor is placed in an acrylic plate calibration mold composed of four arcs with different curvatures, and their Brillouin frequency shift changes are continuously measured from the curved state to the flat state. Brillouin frequency shift variation The change in frequency shift increases with increasing curvature, and then these Brillouin frequency shift changes are... The curvature coefficient at each location was calculated by linear fitting, and the distribution curvature coefficients of the three fiber cores were obtained through analysis. And according to the formula Calculate and determine optical fiber Distribution of fiber core spacing .

[0039] In this embodiment, a torsion resistance test is also required. This process involves holding both ends of the spatial pose sensor, fixing it on the left side, and applying a torsion from the right side. The Brillouin frequency shift of the three fiber cores is measured before and after the 90° torsion, under the same curvature. .

[0040] In one specific embodiment, the specific steps for reconstructing the three-dimensional spatial pose of the distributed fiber optic spatial pose sensor 1 are as follows: In the preset coordinate system, according to the strain-curvature transformation formula Solve for the curvature on the optical fiber of the distributed optical fiber spatial pose sensor 1. and bending direction angle ;in For optical fiber The change in strain. For optical fiber fiber core pitch, For optical fiber The preset angle with the x-axis of the coordinate system; Substitute the desired curvature and bending direction angle into the Bishop frame:

[0041] in, for The tangent vector at the point pointing in the direction of curvature. and Curvature Based on the bending direction angle of mutually perpendicular unit vectors and The projection in the direction, and and Commonly perpendicular to direction; By tangent vector Points The three-dimensional shape of the sensor is reconstructed. , This is the initial position vector.

[0042] In this embodiment, a spatial pose sensor is wound around a high-precision three-dimensional cylindrical mold with a cylindrical helical curve having a bending radius of 10 cm and a pitch of 20 cm. The strain values ​​of the three optical fibers are measured using a Brillouin optical time-domain reflectometer. The curvature and bending direction angle are calculated using a bending-strain theory model, and then the spatial pose of the optical fibers is reconstructed using a Bishop framework. The three-dimensional spatial pose reconstruction result is as follows: Figure 5As shown, the differential pulse pair BOTDA technology based on high-gain fiber proposed in this invention can improve strain spatial resolution and strain accuracy. This fiber ensures that while improving spatial resolution, the Brillouin gain spectrum has a high signal-to-noise ratio, thereby improving strain measurement accuracy and realizing high-precision spatial pose reconstruction.

Claims

1. A torsion-resistant distributed fiber optic spatial pose sensor, characterized in that, include: A base liner (5) is made of nickel-titanium alloy wire; the surface of the base liner (5) is engraved with a plurality of V-grooves (4) along its axial direction, and the plurality of V-grooves (4) are symmetrically distributed along the circumference of the base liner (5); Several sensing optical fibers (6) corresponding to several V-grooves (4) are fixed in their respective V-grooves (4).

2. The sensor according to claim 1, characterized in that, Specifically, there are 3 V-grooves (4) and 3 sensing fibers (6), and the 3 V-grooves (4) are distributed at 120° intervals. The sensing fibers are fixed in different V-grooves (4) with glue. The sensing fibers (6) are high Brillouin gain dispersion fibers.

3. The sensor according to claim 1, characterized in that, It also includes a stainless steel tube (7) with an outer diameter larger than the nickel-titanium alloy wire, which is sleeved on the outside to assist the sensing optical fiber (6); it is fixed with glue to fit tightly into the V-groove (4).

4. A three-dimensional spatial pose measurement system, characterized in that, include: The distributed optical fiber spatial pose sensor (1); The strain measurement module (2) is optically connected to the sensing fiber (6) of the sensor (1) and is used to measure the strain information generated by the deformation of the distributed fiber spatial pose sensor (1). The reconstruction device (3) is electrically connected to the strain measurement module (2) and is used to calculate and reconstruct the spatial pose of the distributed fiber optic spatial pose sensor (1) based on the strain information.

5. The system according to claim 4, characterized in that, The strain measurement module (2) is a Brillouin optical time-domain reflectometer (BOTDA) based on differential pulse pair technology; the reconstruction device (3) uses the Bishop framework algorithm to realize spatial pose reconstruction.

6. The system according to claim 5, characterized in that, The strain measurement module (2) includes a laser source (201), a 50:50 coupler (202), a first polarization controller (203), a second polarization controller (204), a first electro-optic modulator (205), a second electro-optic modulator (206), a first signal generator (207), a second signal generator (218), a third signal generator (219), a polarization scrambler (208), an optical isolator (209), a pulse modulator (211), an optical amplifier (210), a sensing fiber (6), a first circulator (213), a second circulator (214), a grating (215), a photodetector (216), and an oscilloscope (217). The output terminal (201a) of the laser source (201) is connected to the input terminal (202a) of the coupler (202), and the output terminal of the coupler (202) is connected to the input terminals (203a, 204a) of the two polarization controllers (203, 204); the output terminals (203b, 204b) of the polarization controllers (203, 204) are connected to the input terminals (205a, 206a) of the two electro-optic modulators (205, 206); the output channels (207a, 207b) of the first signal generator (207) are connected to... Connect the RF input terminal (205c) of the first electro-optic modulator (205) to the port (217b) of the oscilloscope (217); connect the output terminal of the first electro-optic modulator (205) to the input terminal (208a) of the polarization scrambler (208); connect the output terminal (218a) of the second signal generator (218) to the RF input terminal (206c) of the second electro-optic modulator (206); connect the output terminal (206b) of the second electro-optic modulator (206) to the input terminal (209a) of the optical isolator (209); connect the polarization scrambler (205c) to the RF input terminal (205c) of the first electro-optic modulator (205); connect the output terminal (205c) of the first electro-optic modulator (205) to the port (217b) of the oscilloscope (217); connect the output terminal (205c) of the first electro-optic modulator (205) to the input terminal (209a) of the optical isolator (209); connect the output terminal (205c) of the second signal generator (218) to the RF input terminal (206c) of the second electro-optic modulator (206); connect the output terminal (206b) of the second electro-optic modulator (206) to the input terminal (209a) of the optical isolator (209); connect the output terminal (205c) of the second signal generator (208) to the RF input terminal (206c) of the second electro-optic modulator (206); connect the output terminal (206c) of the second electro-optic modulator (206) to the input terminal (209a) of the optical isolator (209); connect the output terminal (205c) of the second signal generator (208) to the RF input terminal (20 8) The output terminal (208b) is connected to the input terminal (210a) of the optical amplifier (210); the output terminal (210b) of the optical amplifier (210) is connected to the input terminal (211a) of the pulse modulator (211); the output terminal (219a) of the third signal generator (219) is connected to the RF port (211c) of the pulse modulator (211); the output terminal (209b) of the optical isolator (209) is connected to the input terminal of the sensing fiber (6); the output terminal (211b) of the pulse modulator (211) and the sensing fiber (6) 6) The output terminals are respectively connected to the ports (213a, 213b) of the first circulator (213); the output terminal (213c) of the first circulator (213) is connected to the input terminal (214a) of the second circulator (214); the output terminals (214b, 214c) of the second circulator (214) are respectively connected to the input terminal (215a) of the grating (215) and the input terminal (216a) of the photodetector (216); the output terminal (216b) of the photodetector (216) is connected to the input terminal (217a) of the oscilloscope (217).

7. A method for measuring three-dimensional spatial pose, characterized in that, The three-dimensional spatial pose measurement system according to any one of claims 4 to 6 is adopted, and includes the following steps: The distributed Brillouin frequency shift of all sensing fibers (6) in the distributed optical fiber spatial pose sensor (1) is measured by the strain measurement module (2). and obtain distributed strain information. ; The reconstruction device (3) receives the distributed strain information. And convert it into the curvature of each point along the line of the sensor (1). and bending direction angle Based on the Bishop framework algorithm, utilizing the curvature and bending direction angle The three-dimensional spatial pose of the distributed fiber optic spatial pose sensor (1) is reconstructed.

8. The method according to claim 7, characterized in that, Before the reconstruction device (3) performs reconstruction, a calibration step is also included: placing the distributed fiber optic spatial pose sensor (1) in a calibration mold and measuring its first... The change in Brillouin frequency shift of each optical fiber The curvature coefficient at each location is calculated using linear fitting. And according to the formula Calculate and determine optical fiber Distribution of fiber core spacing .

9. The method according to claim 7, characterized in that, The distributed Brillouin frequency shift variation of all sensing fibers (6) in the distributed fiber spatial pose sensor (1) is measured. and obtain distributed strain information. The specific steps are as follows: The strain measurement module (2) generates pump light and probe light respectively and injects them into both ends of all sensing fibers (6) in the distributed optical fiber spatial pose sensor (1); The pump light is modulated by a double pulse, and the probe light is modulated by a double-sideband modulation with a suppressed carrier. Stimulated Brillouin scattering occurs through the modulated pump light and probe light; The amplified probe light is detected to acquire Brillouin time-domain signals; The distributed Brillouin frequency shift was obtained by probing the optical frequency using step scanning and performing Lorentz fitting on the Brillouin gain spectrum. ; Based on the relationship between Brillouin frequency shift and strain and temperature Calculate the distributed strain information after fiber bending ,in It is the change in temperature. and These are the temperature and strain coefficient of the optical fiber, respectively.

10. The method according to claim 8, characterized in that, The specific steps for reconstructing the three-dimensional spatial pose of the distributed fiber optic spatial pose sensor (1) are as follows: In the preset coordinate system, according to the strain-curvature transformation formula The curvature on the optical fiber of the distributed optical fiber spatial pose sensor (1) is solved. and bending direction angle ;in For optical fiber The change in strain. For optical fiber fiber core pitch, For optical fiber The preset angle with the x-axis of the coordinate system; Substitute the desired curvature and bending direction angle into the Bishop frame: in, for The tangent vector at the point pointing in the direction of curvature. and Curvature Based on the bending direction angle of mutually perpendicular unit vectors and The projection in the direction, and and Commonly perpendicular to direction; By tangent vector Points The three-dimensional shape of the sensor is reconstructed. , This is the initial position vector.

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