A low cross-track interference Fabry-Perot acceleration sensor and its optimization method

Abstract

The application discloses a F-P acceleration sensor with low transverse cross interference and an optimization method thereof, and belongs to the technical field of optical fiber sensors.The sensor comprises a sensitive structure, a base, a shell, and an optical fiber probe.The sensitive structure comprises a sensitive diaphragm, a center mass block, and a peripheral mass block.The base is connected with the shell and clamps and fixes the sensitive structure.The shell is provided with an optical fiber fixing seat, and the optical fiber probe is installed on the optical fiber fixing seat.A F-P interference cavity is formed between the optical fiber probe and the center mass block.The center mass block generates displacement in response to external acceleration, and changes the cavity length of the F-P interference cavity.The acceleration information is obtained by demodulating the interference signal.Under the action of transverse acceleration, the inertial torque generated by the peripheral mass block and the inertial torque generated by the center mass block at least partially offset each other, so as to inhibit the transverse displacement of the center mass block.The application has the advantages of stable assembly, high-sensitivity axial acceleration measurement, offsetting mechanism, effective inhibition of transverse cross interference, and better measurement precision.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic sensor technology, specifically relating to a Fabry-Perot accelerometer with low lateral cross-interference and its optimization method. Background Technology

[0002] Accelerometers, as key devices for detecting changes in acceleration during object motion, are widely used in structural health monitoring, earthquake monitoring, aerospace, and precision engineering. In complex multiaxial vibration environments, sensors not only need high sensitivity and appropriate frequency response, but also good resistance to lateral cross-interference to ensure the accuracy of measurement results.

[0003] As an improvement, accelerometers are mainly classified into capacitive, piezoresistive, piezoelectric, and optical types based on different sensing mechanisms. Among them, traditional accelerometers based on electrical signal output suffer from insufficient stability and limited anti-interference capabilities under strong electromagnetic interference or extreme environments. In contrast, fiber optic Fabry-Perot (FP) accelerometers based on fiber optic sensing technology utilize optical signals as information carriers, offering advantages such as strong anti-electromagnetic interference capabilities, high sensitivity, compact structure, and suitability for harsh environments, and are gradually becoming a research hotspot.

[0004] However, current research on fiber optic Fabry-Perot accelerometers primarily focuses on improving axial sensitivity and frequency response performance, with insufficient attention paid to cross-interference caused by lateral acceleration. Under multi-axis vibration conditions, lateral acceleration is transmitted to the sensing element through structural coupling, causing the output signal to deviate from the true value, thereby reducing measurement accuracy, especially in the detection of weak vibrations. In summary, current accelerometers have relatively insufficient lateral cross-interference resistance, are relatively difficult to optimize structural parameters, and their measurement accuracy needs further improvement. Summary of the Invention

[0005] This invention provides a Fabry-Perot accelerometer with low lateral cross-interference and its optimization method, aiming to solve the problems of insufficient lateral cross-interference resistance, relatively difficult structural parameter optimization, and the need for further optimization of measurement accuracy in current accelerometers.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a Fabry-Perot accelerometer with low lateral cross-interference, comprising a sensing structure, a base, a housing, and an optical fiber probe; wherein: The sensitive structure is located between the base and the outer shell. The sensitive structure includes a sensitive diaphragm, a central mass block and a peripheral mass block. The central mass block is located in the central area of ​​the sensitive diaphragm and the peripheral mass block is located in the peripheral area of ​​the sensitive diaphragm and is arranged around the central mass block. The base connects to the outer shell and clamps and fixes the sensitive structure. The outer shell is equipped with a fiber optic mounting base, and the fiber optic probe is installed on the fiber optic mounting base. A Fabry-Perot interferometer cavity is formed between the fiber optic probe and the central mass block. The central mass block can generate displacement in response to external acceleration, so as to change the cavity length of the Fabry-Perot interferometer cavity. Acceleration information is obtained by demodulating the interference signal. Under the action of lateral acceleration, the inertial torque generated by the outer mass block is at least partially canceled out by the inertial torque generated by the central mass block, so as to suppress the lateral displacement of the central mass block.

[0007] In some embodiments, the sensitive diaphragm is provided with a central mounting plate, an inner beam, an inner frame, an outer beam, and a fixing frame; the central mounting plate is located at the center of the sensitive diaphragm, the fixing frame is located at the boundary of the sensitive diaphragm, the inner frame is located between the fixing frame and the central mounting plate, the inner beam is located between the inner frame and the central mounting plate, and the outer beam is located between the fixing frame and the inner frame; a central mass block is located on the central mounting plate, and a peripheral mass block is located on the outer beam.

[0008] Furthermore, there are four inner beams and four outer beams. The four inner beams are arranged in a cross shape between the inner frame and the central mounting plate; the four outer beams are arranged in a cross shape between the fixed frame and the inner frame.

[0009] Furthermore, the outer beam is an irregularly shaped beam with a trapezoidal transition in the middle, with one end connected to the fixed frame and the other end connected to the inner frame.

[0010] Furthermore, the outer mass blocks are set as four trapezoidal structures, and the four outer mass blocks are symmetrically distributed around the central mass block. Each outer mass block is narrower on the side closer to the inner frame and wider on the side closer to the fixed frame.

[0011] In some embodiments, the side wall of the base is provided with an M1 threaded hole and a countersunk through hole, and the bottom surface of the base is provided with an M4 threaded blind hole; the M1 threaded hole is used to fix the sensitive structure to the base; the through hole is used for screws to pass through so as to connect the base and the sensitive structure to the housing; the M4 threaded blind hole is used to fix the sensor to the working platform.

[0012] In some embodiments, the side wall of the housing is provided with an M3 threaded hole and a countersunk hole. The M3 threaded hole is used to connect the base and the sensitive structure to the housing, and the countersunk hole is used to accommodate the screw head for fixing the sensitive structure to the base, so that the housing is fitted to the base. The fiber optic mounting base is provided with an M6 threaded hole for installing a through screw and adjusting the fixed position of the fiber optic probe.

[0013] In some implementations, the end face of the fiber optic probe is a polished reflective surface R1, and the top face of the central mass block is a polished reflective surface R2. The reflective surfaces R1 and R2 are positioned opposite each other to form a Fabry-Perot interference cavity, and the initial cavity length of the Fabry-Perot interference cavity is determined by the position of the end face of the fiber optic probe.

[0014] In some implementations, both the base and the outer shell are box-shaped structures, with the base and the outer shell having the same cross-sectional dimensions, and the sensitive structure is clamped between the base and the outer shell by screws.

[0015] This invention also provides an optimization method for a Fabry-Perot accelerometer with low lateral cross-interference, which is based on the aforementioned Fabry-Perot accelerometer with low lateral cross-interference and includes the following steps: S1. Establish a finite element simulation model of the sensitive structure of the Fabry accelerometer with low lateral cross-interference, and obtain the mechanical and frequency response data of the sensitive structure under the applied acceleration excitation. The data includes the displacement of the central mass block under acceleration in the sensitive direction, the displacement of the central mass block under lateral interference acceleration, and the characteristic frequency response. Use Latin hypercube sampling to generate multiple sets of structural dimension combinations of the sensitive structure, and construct a dataset of different structural parameter combinations and corresponding performance through automated batch simulation. S2. Based on the dataset, a nonlinear mapping model between the structural parameters of the sensitive structure and the performance indicators of the sensor is established using a neural network. S3. Based on the nonlinear mapping model and combined with the optimization algorithm, the structural parameters of the sensitive structure are optimized under the preset constraints to obtain the optimal combination of structural parameters that meets the comprehensive performance requirements.

[0016] Compared with the prior art, the Fabry-Perot accelerometer sensor with low lateral cross-interference of the present invention has the following beneficial effects: In this invention, external acceleration first acts on the sensor housing, which consists of a base and an outer shell. This acceleration is transmitted to the internal sensitive structure via a clamping and fixing relationship, causing the central mass block to displace in response to the acceleration. The fiber optic probe is fixed to the fiber optic mounting base on the outer shell. After the optical signal exits from the fiber optic probe, it returns through the Fabry-Perot interferometer cavity, and the interference signal is output along the same fiber optic loop. The mechanical transmission path and the optical detection path are independent and do not interfere with each other. The central mass block, as an inertial mass element, reflects the magnitude of the external acceleration through its displacement. This displacement is then converted into a change in the cavity length of the Fabry-Perot interferometer cavity. By detecting the interference signal, the cavity length change can be deduced, and the acceleration value can be obtained. This allows the acceleration information to be output in the form of an optical signal, ensuring, to a certain extent, the stability and anti-interference capability of the measurement signal.

[0017] On the other hand, the peripheral mass blocks of this invention are simultaneously subjected to inertial forces under lateral acceleration. Since the peripheral mass blocks are arranged around the central mass block, the inertial torque generated in the lateral acceleration direction is opposite to the inertial torque generated by the central mass block. By adjusting the mass and arrangement of the peripheral mass blocks, the torques can at least partially cancel each other out, reducing the combined torque acting on the central mass block, suppressing the tilting and lateral displacement of the central mass block, so that the displacement of the central mass block is mainly a translational displacement in the axial direction. The change in the cavity length of the Fabry-Perot interferometer mainly reflects the axial acceleration information, weakening the coupling interference of lateral acceleration on the axial measurement channel, and improving the measurement accuracy of the sensor in a multi-axis vibration environment. Attached Figure Description

[0018] The accompanying drawings are provided to further understand the invention and constitute a part of this invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0019] Figure 1 An exploded view of the fiber optic Fabry-Perot accelerometer structure in an embodiment of the present invention, which provides a Fabry-Perot accelerometer with low lateral cross-interference. Figure 2 This is a schematic diagram of the sensitive structure of the fiber optic Fabry-Perot accelerometer sensor in an embodiment of the present invention with low lateral cross-interference. Figure 3 This is a schematic diagram of the structure of the sensitive diaphragm of the fiber optic Fabry-Perot accelerometer in an embodiment of the present invention with low lateral cross-interference; Figure 4 This is a schematic diagram of the base structure of the fiber optic Fabry-Perot accelerometer in an embodiment of the present invention, which provides a Fabry-Perot accelerometer with low lateral cross-interference. Figure 5 This is a schematic diagram of the bottom surface of the fiber optic Fabry-Perot accelerometer base in an embodiment of the present invention, which provides a Fabry-Perot accelerometer with low lateral cross-interference. Figure 6 This is a schematic diagram of the structure of the housing of the fiber optic Fabry-Perot accelerometer in an embodiment of the present invention with low lateral cross-interference. Figure 7 This is a schematic diagram illustrating the structure and working principle of a fiber optic Fabry-Perot accelerometer sensor in an embodiment of the present invention with low lateral cross-interference. Figure 8 This is a simplified model of the sensor sensing structure and a schematic diagram of the lateral anti-crossing interference mechanism in an embodiment of the Fabry-Perot accelerometer with low lateral cross-interference according to the present invention. Figure 9This is a flowchart illustrating an embodiment of the optimization method for a Fabry-Perot accelerometer with low lateral cross-interference according to the present invention.

[0020] Among them, 1. Sensitive structure, 11. Sensitive diaphragm, 111. Central mounting plate, 112. Inner beam, 113. Inner frame, 114. Outer beam, 115. Fixing frame, 116. M1 through hole, 117. M3 through hole, 12. Central mass block, 13. Outer mass block, 2. Base, 21. M1 threaded hole, 22. Through hole, 23. M4 threaded blind hole, 3. Outer shell, 31. Fiber optic fixing seat, 32. M3 threaded hole, 33. Countersunk hole, 34. M6 threaded hole, 4. Fiber optic probe. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] Fiber Fabry-Perot accelerometers are susceptible to lateral acceleration interference in multi-axis vibration environments, leading to decreased measurement accuracy. Furthermore, the performance characteristics of different sensors are mutually constrained, making it difficult to effectively suppress cross-interference caused by lateral acceleration while ensuring high sensor sensitivity and suitable operating bandwidth. In addition, the sensors have numerous sensitive structural parameters with nonlinear mappings to their performance, and traditional design methods rely heavily on experience and finite element simulation iterations, resulting in long design times, low efficiency, and high costs.

[0028] Based on this, such as Figure 1 As shown, this invention provides a Fabry-Perot accelerometer with low lateral cross-interference, comprising a sensing structure 1, a base 2, a housing 3, and an optical fiber probe 4; wherein: The sensitive structure 1 is disposed between the base 2 and the outer shell 3. The sensitive structure 1 includes a sensitive diaphragm 11, a central mass block 12 and a peripheral mass block 13. The central mass block 12 is disposed in the central area of ​​the sensitive diaphragm 11, and the peripheral mass block 13 is disposed in the peripheral area of ​​the sensitive diaphragm 11 and arranged around the central mass block 12. The base 2 is connected to the outer shell 3 and clamps and fixes the sensitive structure 1. The outer shell 3 is provided with an optical fiber fixing seat 31, and the optical fiber probe 4 is installed on the optical fiber fixing seat 31. A Fabry-Perot interferometer cavity is formed between the fiber optic probe 4 and the central mass block 12. The central mass block 12 can generate displacement in response to external acceleration in order to change the cavity length of the Fabry-Perot interferometer cavity and obtain acceleration information by demodulating the interference signal. Under the action of lateral acceleration, the inertial torque generated by the outer mass block 13 is at least partially canceled out by the inertial torque generated by the central mass block 12, so as to suppress the lateral displacement of the central mass block 12.

[0029] The top of the outer casing 3 of this invention is provided with an optical fiber mounting base 31. The optical fiber probe 4 is installed in the optical fiber mounting base 31 by a hollow screw and can be adjusted along the axial direction to achieve precise control of the Fabry-Perot interferometer cavity length. The sensor has a compact overall structure and a stable assembly. At the same time, the optical fiber probe 4 can be adjusted along the axial direction, which facilitates precise control of the initial cavity length of the Fabry-Perot interferometer cavity to meet the measurement requirements under different working conditions.

[0030] In some operating conditions, the sensitive structure 1 of the present invention includes a sensitive diaphragm 11, a central mass block 12, and a peripheral mass block 13. The sensitive diaphragm 11 is provided with a central mounting plate 111, an inner beam 112, an inner frame 113, an outer beam 114, and a fixing frame 115. The central mounting plate 111 is located at the center of the sensitive diaphragm 11 and is used to mount the central mass block 12. The fixing frame 115 is located at the boundary of the sensitive diaphragm 11 and is provided with an M1 through hole 116 and an M3 through hole 117. The M1 through hole 116 is used to fix the sensitive structure 1 to the sensor base 2, and the M3 through hole 117 allows screws connecting the base 2, the sensitive structure 1, and the outer shell 3 to pass through. The inner frame 113 is located between the fixing frame 115 and the central mounting plate 111 to improve the rotational stiffness of the central mass block 12, achieving mechanical isolation and modal separation. The outer beam 114 consists of four cross-shaped beams with trapezoidal transitions in the middle. One end is connected to the fixed frame 115, and the other end is connected to the inner frame 113, serving to support the inner frame 113 and mount the outer mass block 13. The inner beam 112 is a four-beam structure arranged in a cross shape, positioned between the inner frame 113 and the central mounting plate 111, serving to support the central mass block 12 and provide stiffness for the elastic structure control system. The central mass block 12 is mounted on the central mounting plate 111, serving as an inertial structure to sense external vibration signals. The outer mass block 13 consists of four approximately trapezoidal three-dimensional structures mounted on the outer beam 114. The outer mass block 13 is narrower near the inner frame 113 and wider near the fixed frame 115, and is symmetrically distributed around the central mass block 12.

[0031] Furthermore, the inner beam 112 of the present invention provides elastic support for the central mass block 12, enabling the central mass block 12 to generate stable axial displacement under axial acceleration, thereby ensuring the axial sensitivity of the system. The inner frame 113 improves the rotational stiffness of the central mass block 12, enhancing its ability to suppress lateral cross-interference. The outer beam 114 adopts an irregular beam structure with a trapezoidal transition in the middle, which can effectively adjust the equivalent stiffness and stress distribution, optimize the mechanical properties of the sensitive structure 1, avoid stress concentration, and improve the working bandwidth and overload resistance of the sensor. Under lateral acceleration, both the central mass block 12 and the peripheral mass block 13 are subjected to inertial forces. Since the peripheral mass block 13 is symmetrically distributed, the inertial torque it generates is opposite in direction to the inertial torque of the central mass block 12, thereby canceling out the rotation of the central mass block 12, effectively suppressing the coupling transmission of lateral acceleration to the sensitive direction, and reducing the lateral cross-interference of the sensor.

[0032] In some operating conditions, the base 2 of this invention has an M1 threaded hole 21 and a countersunk through hole 22 on its side wall, and an M4 threaded blind hole 23 on its bottom surface. The M1 threaded hole 21 is used to fix the sensitive structure 1 to the base 2. The through hole 22 is used to mate with the M3 through hole 117 to connect the base 2 and the sensitive structure 1 to the housing 3 by screws. The M4 threaded blind hole 23 is used to fix the sensor on the working platform, ensuring the stability of the internal structure of the sensor, while facilitating assembly and disassembly.

[0033] Furthermore, the outer casing 3 of this invention has an M3 threaded hole 32 and a countersunk hole 33 on its side wall, and an optical fiber mounting base 31 on its top. The M3 threaded hole 32 is used to connect the base 2 and the sensitive structure 1 to the outer casing 3. The countersunk hole 33 is used to cover the screw head that fixes the sensitive structure 1 to the base 2, so that the outer casing 3 is tightly and fixedly connected to the base 2, avoiding spatial interference from the screw head. The optical fiber mounting base 31 has an M6 threaded hole 34 for installing a through screw and adjusting the fixed position of the optical fiber probe 4, making the installation and adjustment of the optical fiber probe 4 more convenient.

[0034] In this invention, the end face of the fiber optic probe 4 serves as the reflecting surface R1, and the top surface of the central mass block 12 serves as the reflecting surface R2. The reflecting surfaces R1 and R2 are positioned opposite each other to form a Fabry-Perot interference cavity. The initial cavity length between the end face of the fiber optic probe 4 and the top surface of the central mass block 12 is determined by the position of the end face of the fiber optic probe 4. The light beam is reflected and transmitted at the reflecting surface R1. The transmitted beam is reflected at the reflecting surface R2 and interferes with the beam reflected at the reflecting surface R1. Acceleration information is obtained by demodulating the interference signal. Under axial acceleration, the central mass block 12 is displaced axially, causing a change in the distance between the reflecting surfaces R2 and R1. This change in cavity length causes a change in the interference light signal. The corresponding acceleration information can be obtained by demodulating the interference signal. This method features high sensitivity, strong anti-electromagnetic interference capability, and suitability for long-distance transmission.

[0035] Furthermore, the sensitive diaphragm 11 of the present invention can be integrally formed from a thin metal sheet using laser cutting technology to ensure structural dimensional consistency and processing accuracy. The central mass block 12 and the peripheral mass block 13 are processed independently and assembled with the sensitive diaphragm 11 by bonding, welding or mechanical connection, which improves assembly flexibility and feasibility while ensuring structural strength.

[0036] This invention also provides an optimization method for a Fabry-Perot accelerometer with low lateral cross-interference, comprising the following steps: S1. Establish a finite element simulation model of the sensitive structure 1 of the Fabry accelerometer with low lateral cross-interference, and obtain the mechanical response and frequency response data of the sensitive structure 1 under the applied acceleration excitation. The data includes the displacement of the central mass block 12 under acceleration in the sensitive direction, the displacement of the central mass block 12 under lateral interference acceleration, and the characteristic frequency response. Use Latin hypercube sampling to generate multiple sets of structural dimension combinations of the sensitive structure 1, and construct a dataset of different structural parameter combinations and corresponding performance through automated batch simulation. S2. Based on the dataset, a nonlinear mapping model between the structural parameters of sensitive structure 1 and sensor performance indicators is established using a neural network. S3. Based on the nonlinear mapping model and combined with the optimization algorithm, the structural parameters of the sensitive structure 1 are optimized under the preset constraints to obtain the optimal combination of structural parameters that meets the comprehensive performance requirements.

[0037] In some embodiments, the method of the present invention is specifically performed according to the following steps: S1. Based on finite element simulation, the mechanical and frequency response data of the sensor's sensitive structure 1 under applied acceleration excitation are obtained, including the displacement of the central mass block 12 under acceleration in the sensitive direction, the displacement of the central mass block 12 under lateral disturbance acceleration, and the characteristic frequency response. Different combinations of structural dimensions are generated using Latin hypercube sampling, and automated batch simulation is performed using the MATLAB livelink for COMSOL module to construct a dataset of different combinations of structural parameters and their corresponding performance.

[0038] S2. Based on the dataset, a nonlinear mapping model between structural parameters and sensor performance indicators is established using a neural network method. The performance indicators include axial sensitivity, operating bandwidth, and lateral cross-interference.

[0039] S3. Based on the neural network mapping model, combined with optimization algorithms and target performance indicators, the key parameters of sensitive structure 1 are optimized and solved by multiple objectives, so as to effectively suppress cross interference caused by lateral acceleration while ensuring the high sensitivity and appropriate working bandwidth of the sensor.

[0040] S4. Determine the optimal structural parameters based on the optimization results, and verify the optimization results through finite element simulation to ensure that the optimized structure meets the design requirements.

[0041] The method of this invention constructs a dataset through Latin hypercube sampling and automated batch simulation, establishes a nonlinear mapping model between structural parameters and performance indicators using a neural network, and combines optimization algorithms to solve multi-objective optimization problems, thereby improving design efficiency and achieving synergistic optimization of sensitivity, bandwidth and lateral anti-interference performance to a certain extent. At the same time, it can effectively improve the problems caused by multiple structural parameters and strong performance coupling.

[0042] The present invention will be further described in detail below through specific embodiments.

[0043] like Figures 1-6 As shown, Figure 1 This is an exploded view of the sensor structure in this invention. Both the base 2 and the outer shell 3 are box-like structures, positioned vertically opposite each other with identical cross-sectional dimensions. The sensitive structure 1, aligned and clamped between the two, is reliably connected using screws. An optical fiber mounting base 31 is located on the top of the outer shell 3. The optical fiber probe 4 is housed within a through screw in the optical fiber mounting base 31 and its position can be adjusted axially to precisely adjust the length of the Fabry-Perot interferometer cavity.

[0044] like Figure 2 and Figure 3As shown, the sensitive diaphragm 11 is provided with a central mounting plate 111, an inner beam 112, an inner frame 113, an outer beam 114, and a fixing frame 115. The central mounting plate 111 is located at the center of the sensitive diaphragm 11 and is used to mount the central mass block 12. The fixing frame 115 is located at the outer boundary of the sensitive diaphragm 11 and has M1 through holes 116 and M3 through holes 117. The M1 through hole 116 is used to fix the sensitive structure 1 to the base 2, and the M3 through hole 117 is used for screws connecting the base 2, the sensitive structure 1, and the outer shell 3 to pass through. The inner frame 113 is located between the central mounting plate 111 and the fixing frame 115, and is connected to the fixing frame 115 via the outer beam 114 and to the central mounting plate 111 via the inner beam 112. This design improves the rotational stiffness of the central region, achieving mechanical isolation and modal separation between the central mass block 12 and the external structure. Four inner beams 112 are arranged in a cross-shaped symmetrical distribution between the inner frame 113 and the central mounting plate 111. They support the central mass block 12 and provide elastic restoring force, thus determining the equivalent stiffness of the sensitive structure 1. Four outer beams 114 are arranged in a cross-shaped symmetrical distribution and are irregular beam structures with a trapezoidal transition in the middle. One end of each beam is connected to the fixed frame 115, and the other end is connected to the inner frame 113. They support the inner frame 113 and serve as the mounting base for the outer mass blocks 13. The outer mass blocks 13 are mounted on the outer beams 114 and are symmetrically distributed around the central mass block 12 circumferentially. They are narrower on the side closer to the inner frame 113 and wider on the side farther from the inner frame 113 and closer to the fixed frame 115, thus forming a mass distribution pattern that is conducive to torque cancellation under lateral acceleration. The central mass block 12 is mounted on the central mounting plate 111 and serves as an inertial sensing element to sense external acceleration excitation. The outer mass block 13 is a plurality of approximately trapezoidal three-dimensional structures, which are fixed to the outer beam 114 by assembly. Preferably, the sensitive diaphragm 11, the central mass block 12 and the outer mass block 13 are independently processed from metal sheets and metal blocks by laser cutting process. After processing, the central mass block 12 and the outer mass block 13 are assembled to the sensitive diaphragm 11 by bonding, welding or mechanical fixing to ensure structural dimensional accuracy and assembly reliability.

[0045] like Figure 4 and Figure 5 As shown, the side wall of the base 2 of the present invention is provided with an M1 threaded hole 21 and a countersunk through hole 22. The M1 threaded hole 21 is used to fix the sensitive structure 1 to the base 2, and the through hole 22 is used to connect and fix the base 2, the sensitive structure 1 and the outer shell 3 with screws. The bottom surface of the base 2 is provided with a plurality of M4 threaded blind holes 23 for fixing the sensor as a whole to the external working platform.

[0046] like Figure 6As shown, the side wall of the outer casing 3 of the present invention is provided with an M3 threaded hole 32 and a countersunk hole 33. The M3 threaded hole 32 is used to engage with a screw to fix the base 2 and the sensitive structure 1 to the outer casing 3. The countersunk hole 33 is used to accommodate the screw head that fixes the sensitive structure 1 to the base 2, thereby ensuring that the outer casing 3 can fit tightly with the base 2. The fiber optic mounting base 31 at the top of the outer casing 3 is provided with an M6 threaded hole 34 for installing a through screw and realizing the axial position adjustment and fixation of the fiber optic probe 4.

[0047] like Figure 7 As shown, in this invention, the polished end face of the fiber optic probe 4 serves as the reflecting surface R1, and the polished top surface of the central mass block 12 serves as the reflecting surface R2. Reflecting surfaces R1 and R2 are positioned opposite each other, together forming a Fabry-Perot interferometer cavity. The initial cavity length of the interferometer cavity is denoted as... Its size is determined by the axial position of the fiber optic probe 4 and can be precisely controlled by adjusting the position of the fiber optic probe 4 in the fiber optic mount. After the incident light exits from the end face of the fiber optic probe 4, it undergoes partial reflection and partial transmission at the reflecting surface R1. The transmitted light propagates to the reflecting surface R2, is reflected again, and returns to interfere with the beam reflected at the reflecting surface R1. The interference light intensity... It can be represented as: ; in, and These are the intensities of the two interferometric beams, The instantaneous cavity length of the FP cavity. The incident light wavelength, This is the initial phase. Therefore, it can be seen that the interference intensity increases with the cavity length. The changes are periodic, so the changes in cavity length can be deduced by detecting changes in light intensity.

[0048] From a mechanical perspective, the sensitive structure can be equivalent to a single-degree-of-freedom mass-spring system, where the mass of the central mass block 12 is denoted as . The internal beam 112 and other elastic structures provide equivalent stiffness. In axial acceleration Under the action, the central mass block 12 is subjected to inertial force. And under the constraint of the elastic structure, displacement is generated. x Its motion satisfies: ; in, Here is the equivalent damping coefficient. Under low-frequency or quasi-static conditions, the effects of the inertial and damping terms can be neglected, and the above equation can be approximated as: ; Right now: ; Due to the displacement of the central mass block 12 This directly causes a change in the position of the reflecting surface R2, therefore the change in the cavity length of FP... satisfy: ; This shows that, given a fixed structural parameter, the change in cavity length... Acceleration with external forces The relationship is linear. By substituting the values ​​into the expression for interference light intensity, the correspondence between acceleration and light intensity signal can be established. Accurate measurement of acceleration can be achieved by demodulating the interference signal.

[0049] Figure 8 This is a simplified model of the sensor's sensitive structure and a schematic diagram of its lateral anti-cross-interference mechanism in this invention. In practical applications, acceleration excitation typically has multi-axial components. When the sensor is subjected to lateral acceleration, if only a single central mass block structure is used, the central mass block will tilt or twist under the action of inertial force, causing the reflecting surface R2 to tilt or undergo non-axial displacement relative to the reflecting surface R1. This results in a non-target change in the length of the interference cavity, generating lateral cross-interference and reducing measurement accuracy. As shown on the left side of the figure, under lateral acceleration... Under the action, the central mass block 12 not only generates lateral inertial force It can also generate a torsional moment around the center due to the flexibility of the support. This causes the central mass block 12 to tilt, resulting in the reflector R2 tilting relative to the reflector R1, which in turn introduces additional non-target cavity length variation error. .

[0050] To suppress the aforementioned lateral cross-interference, this invention symmetrically arranges multiple peripheral mass blocks 13 around the central mass block 12, which are connected to the inner frame structure via outer beams 114. When lateral acceleration acts on the sensor, both the central mass block 12 and the peripheral mass blocks 13 generate inertial forces, forming corresponding torques under the constraint of the elastic structure. Since the peripheral mass blocks 13 are symmetrically arranged, the peripheral mass blocks distributed vertically or horizontally generate inertial torques of equal magnitude but opposite direction in the lateral acceleration direction. These torques are transmitted to the inner beam 112 through the outer beams 114 and the inner frame 113, effectively canceling out the inertial forces generated by the central mass block 12. Under this torque cancellation mechanism, the combined torque acting on the central mass block 12 is significantly reduced, thereby effectively suppressing the tilting and lateral displacement of the central mass block 12, causing it to move primarily along the axial direction. Simultaneously, the introduction of the inner frame 113 improves the overall rotational stiffness of the central region, giving the sensitive structure stronger torsional resistance under lateral excitation, achieving mechanical isolation and modal separation, and further weakening the influence of lateral vibration on axial measurement. As shown on the right, let the mass of a single peripheral mass block be... When lateral acceleration When the action occurs, each of the outer mass blocks generates inertial force. And generate a moment relative to the center of the structure. Because the outer mass blocks 13 are symmetrically distributed, the moments they generate on both sides of the structure are opposite in direction and equal in magnitude. Simultaneously, these moments are transmitted to the inner beam 112 through the outer beam 114 and inner frame 113, interacting with the torque generated by the central mass block 12. They cancel each other out, so that the total torque of the central mass block 12 satisfies: ; Under this torque balance condition, the rotation of the central mass block 12 is effectively suppressed, and its motion is mainly manifested as axial translation, thereby reducing the change in cavity length caused by lateral acceleration. Significantly reduced. Furthermore, the inner frame 113 increases the rotational stiffness of the central region, effectively increasing the system's torsional stiffness. This results in angular displacement under the same lateral excitation. satisfy: ; in This is the resultant torque. With... The increase, This significantly reduces the tilt of the reflective surface R2, thereby further reducing its inclination.

[0051] In summary, this invention achieves decoupling between lateral acceleration and axial measurement from a mechanical structural perspective by using the symmetrical inertial torque cancellation mechanism of the outer mass block 13 and the improvement of rotational stiffness of the inner frame 113. This makes the change in FP cavity length mainly determined by axial acceleration, thereby improving the sensor's lateral anti-crossing interference capability and measurement accuracy.

[0052] like Figure 9 As shown, to address the problems of numerous structural parameters, mutual constraints on sensor performance, and nonlinear mapping between parameters and performance in fiber optic Fabry-Perot accelerometers, and the time-consuming, inefficient, and costly nature of traditional finite element analysis methods, this invention provides a method for optimizing the sensitive structural parameters. The specific implementation is as follows: First, a finite element simulation model of the sensing structure of the fiber optic Fabry-Perot accelerometer was established. Material parameters, boundary conditions, and load types were appropriately set to obtain the mechanical and frequency response data of the sensor's sensing structure under applied acceleration excitation, including the displacement of the central mass block under acceleration in the sensitive direction, the displacement of the central mass block under lateral disturbance acceleration, and the characteristic frequency response. To improve the uniformity of the sample space coverage, after setting a reasonable range of variables, the Latin hypercube sampling method was used to perform multidimensional random sampling of the key dimensional parameters of the sensing structure, generating multiple sets of structural parameter combinations. Based on the MATLAB livelink for COMSOL module, the simulation process was automated and batch-processed. The parameters of each set were calculated to obtain the corresponding performance indicators such as the displacement of the central mass block, natural frequency, and lateral response, thereby constructing the original dataset between structural parameters and sensor performance.

[0053] Secondly, based on the aforementioned dataset, a neural network method was selected to establish a nonlinear mapping model between structural parameters and performance indicators. Using structural dimensions as input variables and sensor sensitivity, operating bandwidth, and lateral cross-interference response as output variables, the neural network was trained and validated to accurately characterize the coupling relationship between complex structural parameters and performance, thereby replacing the high computational cost of traditional finite element simulation.

[0054] Then, based on the established neural network mapping model, an optimization algorithm is introduced to optimize the design of sensitive structural parameters. A multi-objective optimization problem is constructed, and a genetic algorithm is used to iteratively search for the structural parameters to obtain the optimal parameter combination that meets the comprehensive performance requirements. This achieves the goal of effectively suppressing cross-interference caused by lateral acceleration while ensuring high sensor sensitivity and appropriate operating bandwidth.

[0055] Finally, the optimized structural parameters were re-imported into the finite element model for simulation verification to ensure the accuracy and reliability of the optimization results. Based on this, the final sensitive structure design scheme was determined, providing theoretical basis and parameter support for subsequent sensor fabrication, manufacturing, and experimental testing.

[0056] Finally, it should be noted that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Anyone skilled in the art can readily implement the present invention according to the description and above. Any modifications, alterations, or equivalent variations made using the technical content disclosed above are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, or variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A Fabry-Perot accelerometer with low lateral cross-interference, characterized in that, It includes a sensitive structure (1), a base (2), a housing (3), and an optical fiber probe (4); wherein: The sensitive structure (1) is disposed between the base (2) and the outer shell (3). The sensitive structure (1) includes a sensitive diaphragm (11), a central mass block (12) and a peripheral mass block (13). The central mass block (12) is disposed in the central region of the sensitive diaphragm (11), and the peripheral mass block (13) is disposed in the peripheral region of the sensitive diaphragm (11) and arranged around the central mass block (12). The base (2) is connected to the outer shell (3) and clamps and fixes the sensitive structure (1). The outer shell (3) is provided with an optical fiber fixing seat (31). The optical fiber probe (4) is installed on the optical fiber fixing seat (31). The fiber optic probe (4) and the central mass block (12) form a Fabry-Perot interferometer cavity. The central mass block (12) can generate displacement in response to external acceleration in order to change the cavity length of the Fabry-Perot interferometer cavity and obtain acceleration information by demodulating the interference signal. Under the action of lateral acceleration, the inertial torque generated by the outer mass block (13) is at least partially canceled out by the inertial torque generated by the central mass block (12) so as to suppress the lateral displacement of the central mass block (12).

2. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 1, characterized in that, The sensitive diaphragm (11) is provided with a central mounting plate (111), an inner beam (112), an inner frame (113), an outer beam (114), and a fixing frame (115); the central mounting plate (111) is located at the center of the sensitive diaphragm (11), the fixing frame (115) is located at the boundary of the sensitive diaphragm (11), the inner frame (113) is located between the fixing frame (115) and the central mounting plate (111), the inner beam (112) is located between the inner frame (113) and the central mounting plate (111), and the outer beam (114) is located between the fixing frame (115) and the inner frame (113); the central mass block (12) is located on the central mounting plate (111), and the peripheral mass block (13) is located on the outer beam (114).

3. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 2, characterized in that, The inner beam (112) and the outer beam (114) are each provided with four beams. The four inner beams (112) are arranged in a cross shape between the inner frame (113) and the central mounting piece (111); the four outer beams (114) are arranged in a cross shape between the fixed frame (115) and the inner frame (113).

4. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 3, characterized in that, The outer beam (114) is an irregular beam with a trapezoidal transition in the middle. One end of the outer beam (114) is connected to the fixed frame (115), and the other end is connected to the inner frame (113).

5. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 2, characterized in that, The peripheral mass blocks (13) are configured as four trapezoidal structures. The four peripheral mass blocks (13) are symmetrically distributed around the central mass block (12). Each peripheral mass block (13) is narrow on the side closer to the inner frame (113) and wide on the side closer to the fixed frame (115).

6. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 1, characterized in that, The base (2) has an M1 threaded hole (21) and a countersunk through hole (22) on its side wall, and an M4 threaded blind hole (23) on its bottom surface. The M1 threaded hole (21) is used to fix the sensitive structure (1) to the base (2). The through hole (22) is used for screws to pass through so as to connect the base (2) and the sensitive structure (1) to the housing (3). The M4 threaded blind hole (23) is used to fix the sensor to the working platform.

7. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 1, characterized in that, The outer shell (3) has an M3 threaded hole (32) and a countersunk hole (33) on its side wall. The M3 threaded hole (32) is used to connect the base (2) and the sensitive structure (1) to the outer shell (3). The countersunk hole (33) is used to accommodate the screw head for fixing the sensitive structure (1) to the base (2), so that the outer shell (3) fits snugly to the base (2). The fiber optic mounting base (31) has an M6 threaded hole (34) for installing a through screw and adjusting the fixed position of the fiber optic probe (4).

8. The Fabry-Perot accelerometer with low lateral cross-interference according to claim 1, characterized in that, The end face of the fiber optic probe (4) is a polished reflective surface R1, and the top face of the central mass block (12) is a polished reflective surface R2. The reflective surfaces R1 and R2 are arranged opposite to each other to form a Fabry-Perot interference cavity. The initial cavity length of the Fabry-Perot interference cavity is determined by the end face position of the fiber optic probe (4).

9. A Fabry-Perot accelerometer with low lateral cross-interference according to claim 1, characterized in that, The base (2) and the outer shell (3) are both box structures. The base (2) and the outer shell (3) have the same cross-sectional dimensions. The base (2) and the outer shell (3) clamp the sensitive structure (1) with screws.

10. An optimization method for a Fabry-Perot accelerometer with low lateral cross-interference, based on the Fabry-Perot accelerometer with low lateral cross-interference as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Establish a finite element simulation model of the sensitive structure (1) of the Fabry accelerometer with low lateral cross-interference, and obtain the mechanical response and frequency response data of the sensitive structure (1) under the applied acceleration excitation. The data includes the displacement of the central mass block (12) under the acceleration in the sensitive direction, the displacement of the central mass block (12) under the lateral interference acceleration, and the characteristic frequency response. Use Latin hypercube sampling to generate multiple sets of structural size combinations of the sensitive structure (1), and construct a dataset of different structural parameter combinations and corresponding performance through automated batch simulation. S2. Based on the dataset, a nonlinear mapping model between the structural parameters of the sensitive structure (1) and the sensor performance indicators is established using a neural network. S3. Based on the nonlinear mapping model and combined with the optimization algorithm, the structural parameters of the sensitive structure (1) are optimized in multiple objectives under the preset constraints to obtain the optimal combination of structural parameters that meets the comprehensive performance requirements.

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