A flexible accelerometer based on symmetric split-beam differential optical path

Abstract

The application discloses a flexible accelerometer based on symmetric split-beam differential optical path, and belongs to the technical field of inertial sensing. The accelerometer comprises a base, a mass pendulum with a symmetric double flexible beam structure, a symmetric split-beam differential optical path sensing unit and a servo control circuit. The optical path sensing unit splits a light source into two symmetric light paths through a split-beam prism, respectively irradiates the reflective surfaces on both sides of the mass pendulum, detects displacement by using differential light intensity change, and realizes high-precision acceleration measurement. The structure can effectively suppress common-mode interference such as light source drift and temperature change, and reduce zero offset drift. The servo control circuit realizes closed-loop feedback, and further improves measurement accuracy and linearity. The application combines optical differential detection and a double flexible beam structure, overcomes the problem of precision reduction caused by factors such as friction and aging in traditional accelerometers, and has the advantages of high precision, low drift, strong anti-interference capability and the like.

Description

Technical Field

[0001] This invention relates to the field of inertial sensing technology, and more specifically to a flexible accelerometer based on a symmetrical beam splitting differential optical path. Background Technology

[0002] Flexible pendulum accelerometers are core inertial devices in the field of inertial navigation. Traditional flexible pendulum accelerometers mostly use capacitive or inductive detection principles, which suffer from problems such as susceptibility to electromagnetic interference, large temperature drift, and insufficient microscopic resolution. While existing photoelectric flexible accelerometers have improved measurement accuracy through non-contact photoelectric detection, they still have shortcomings.

[0003] The system is highly sensitive to factors such as optical path deviation in the photoelectric detection optical path, environmental vibration, and temperature changes, which can easily cause instability in the optical signal. Simultaneously, fluctuations in light source intensity, photodetector response drift, and aging of optical components can also lead to fluctuations in the detection signal, thus introducing detection errors.

[0004] These errors are particularly critical in inertial measurement systems, especially in optical accelerometers, where minute changes in the optical signal can be misinterpreted as changes in acceleration, leading to output drift. Over long-term operation, this drift accumulates, severely impacting the system's measurement accuracy and stability, and reducing the equipment's reliability and lifespan.

[0005] Current technologies have not yet solved the problem of photoelectric detection drift, so developing a flexible pendulum accelerometer has become a technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0006] The purpose of this invention is to overcome the problems of large measurement errors, severe drift, and poor stability caused by factors such as mechanical friction, light source drift, temperature changes, and environmental interference in existing flexible accelerometers during long-term operation. The invention provides a flexible accelerometer based on a symmetrical spectroscopic differential optical path, which features high measurement accuracy, good response linearity, strong anti-interference ability, and excellent long-term stability. It is suitable for applications such as inertial navigation that have extremely high requirements for measurement accuracy and system stability.

[0007] To achieve the above objectives, the present invention provides a flexible accelerometer based on a symmetrical beam-splitting differential optical path, comprising: a base 1, a mass pendulum 2, a torque converter 3, a servo control circuit 4, and a symmetrical beam-splitting differential optical path sensing unit 5; the symmetrical beam-splitting differential optical path sensing unit 5 comprises: a light source 6, a beam splitter 7, a first focusing lens 8, a second focusing lens 9, an optical thin film 12, a first photodetector group 10, and a second photodetector group 11; Mass pendulum 2, light source 6, beam splitter 7, first focusing lens 8, second focusing lens 9, first photodetector group 10, and second photodetector group 11 are fixed on base 1; The mass pendulum 2 adopts a symmetrical double flexible beam structure, and symmetrical optical thin films 12 are provided on the upper and lower surfaces of the far end of the flexible ribs of the mass pendulum 2. The light emitted by the light source 6 is split into two symmetrical beams by the beam splitter 7. The beams pass through the first focusing lens 8 and the second focusing lens 9, respectively, and illuminate the optical thin films 12 on the upper and lower surfaces of the mass pendulum 2. The first photodetector group 10 and the second photodetector group 11 respectively receive the light signals reflected by the optical thin films 12 on the upper and lower surfaces of the mass pendulum 2, and convert them into electrical signals and send them to the servo control circuit 4. The servo control circuit 4 is used to obtain the change in the differential light intensity ratio through the received electrical signal, so as to obtain the displacement of the mass pendulum 2, and generate a control signal based on the displacement to drive the torque generator 3, so that the mass pendulum 2 returns to the initial position, thereby realizing closed-loop control.

[0008] Optionally, the mass pendulum 2 is made of monocrystalline silicon or quartz.

[0009] Optionally, the light source 6 is a laser diode with an output wavelength in the visible or near-infrared band.

[0010] Optionally, the beam splitter 7 is a beam splitter cube, which splits the light emitted by the light source 6 into two beams of equal intensity and symmetrical direction.

[0011] Optionally, the reflectivity of the optical thin film 12 is not less than 95%.

[0012] Optionally, a collimating lens is provided in light source 6.

[0013] Optionally, the servo control circuit 4 is specifically used to amplify and filter the received electrical signal.

[0014] Optionally, the base 1 is made of a material with high rigidity and low coefficient of thermal expansion.

[0015] The beneficial effects of this invention are as follows: High-precision measurement: Based on the differential optical path detection mechanism, it can achieve high-sensitivity detection of minute displacements, significantly improving the accuracy of acceleration measurement; it overcomes the problem that existing accelerometers use a single-path asymmetric structure, which has certain limitations in practical applications due to the asymmetry of the optical path structure; Low drift characteristics: The symmetrical optical path design effectively suppresses systematic errors such as light source drift and temperature drift, significantly reducing the long-term zero-bias drift of the sensor; High stability and reliability: The system adopts a double flexible beam structure and a non-contact optical detection method, which avoids traditional mechanical friction and wear, and improves the long-term stability and service life of the system. Strong anti-interference capability: The differential detection mechanism and symmetrical structural design work together to effectively suppress external interference such as environmental vibration and temperature changes; Excellent linear response: The symmetrical structure of the mass pendulum combined with servo closed-loop control ensures that the system has excellent linear response characteristics over a wide range.

[0016] In summary, the high-precision, low-drift flexible accelerometer based on a symmetrical beam splitting differential optical path provided by this invention achieves excellent performance in scenarios requiring high precision and high stability through the synergistic optimization of structural design and optical path detection mechanism, and has broad application prospects and promotional value. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the overall structure of the accelerometer of the present invention; Figure 2 This is a schematic diagram of the symmetrical beam-splitting differential optical path sensing unit of the present invention; Explanation of reference numerals in the attached figures: 1—Base, 2—Mass pendulum, 3—Torque generator, 4—Servo control circuit, 5—Symmetrical beam splitting differential optical path sensing unit, 6—Parallel light source, 7—Beam splitter prism, 8—First focusing lens, 9—Second focusing lens, 10—First photodetector, 11—Second photodetector, 12—Optical thin film. Detailed Implementation

[0019] 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, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0021] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, the present invention discloses a high-precision, low-drift flexible accelerometer based on a symmetrical beam-splitting differential optical path, comprising: a base 1, a mass pendulum 2, a torque generator 3, a servo control circuit 4, and a symmetrical beam-splitting differential optical path sensing unit 5.

[0023] Base 1: Made of a high-rigidity, low-thermal-expansion-coefficient material (such as a low-expansion alloy), it provides stable mechanical support for the various components of the accelerometer, ensuring that the system maintains structural stability in complex environments.

[0024] Mass Pendulum 2: Employs a symmetrical double-flexible beam structure, made of highly elastic, low-internal-friction materials (such as monocrystalline silicon or quartz). The central mass block of Mass Pendulum 2 is fixedly connected to the base 1 at both ends via flexible beams, forming a symmetrical elastic support structure. Under external acceleration, the mass block undergoes a small displacement along the sensitive axis, achieving linear recovery through the double-flexible beam structure, significantly reducing mechanical friction and hysteresis effects, and improving long-term stability.

[0025] Torque generator 3: Connected to the mass pendulum 2, it is used to generate a restoring torque under the drive of the servo control circuit, so that the mass pendulum 2 returns to its initial position, realizes closed-loop control, and improves the system's response speed and measurement accuracy.

[0026] Servo control circuit 4 includes signal acquisition, processing, feedback control and execution modules. It is responsible for receiving the differential signal from the optical path sensing unit, generating control signals to drive torque generator 3, and realizing closed-loop feedback control.

[0027] The structure of the symmetrical beam-splitting differential optical path sensing unit 5 is as follows: Figure 2As shown, it includes: a parallel light source 6, a beam splitter 7, a first focusing lens 8 and a second focusing lens 9, a first photodetector 10 and a second photodetector 11, and an optical thin film 12 disposed on the reflecting surface of the mass pendulum.

[0028] During assembly, the parallel light source 6 and the collimating lens (which can be integrated into the light source module) are installed at the beginning of the optical path, and the beam splitter 7 is located in the center of the optical path, splitting the collimated beam emitted by the light source into two beams of equal intensity and symmetrical direction. Each beam is focused by the focusing lens onto the optical thin films 12 on both sides of the mass pendulum, and the reflected light signals are received by the first photodetector 10 and the second photodetector 11, forming a differential detection structure.

[0029] The symmetrical beam-splitting differential optical path sensing unit employs a non-contact optical detection method, comprising a beam-splitting prism, a parallel light source, a focusing lens, and a symmetrically arranged detector group. The beam emitted from the parallel light source is split into two beams of equal intensity and symmetrical direction by the beam-splitting prism, which then pass through the focusing lens and illuminate two symmetrical positions of the mass pendulum. When the mass pendulum shifts due to external acceleration, the optical path length or reflected light intensity of the two optical paths changes differentially. The detector group collects this differential signal and processes it using the intensity ratio to accurately reflect the displacement, thereby achieving high-sensitivity acceleration detection.

[0030] Furthermore, the symmetrical beam splitting differential optical path structure can effectively suppress the influence of common-mode interference factors such as light source intensity drift, ambient temperature fluctuation, and mechanical vibration, significantly reduce sensor zero-bias drift and measurement noise, and improve the long-term working stability and reliability of the system.

[0031] Furthermore, the servo control circuit is connected to the symmetrical beam splitting differential optical path sensing unit 5 and the mass pendulum to receive differential optical signals and generate control commands based on displacement feedback signals to drive the mass pendulum back to the initial equilibrium position, thereby realizing closed-loop control and further improving the linearity and dynamic response capability of the system.

[0032] The double flexible beam structure of the mass pendulum is symmetrically arranged at both ends of the mass block and fixedly connected to the base, forming a symmetrical restoring force mechanism, which improves the linearity and repeatability of the displacement response.

[0033] The light source is a high-stability laser diode with an output wavelength in the visible or near-infrared band, exhibiting good long-term output stability.

[0034] The beam splitter is a high-precision beam splitting cube that splits the collimated beam into two beams of equal intensity and symmetrical direction, which are used to construct a differential detection structure with strong common-mode suppression capability.

[0035] The photodetector group consists of two photodetectors, which are respectively arranged in the optical path at two symmetrical positions of the mass pendulum. They are used to collect changes in light intensity and output differential signals to calculate the displacement of the mass pendulum.

[0036] The optical thin film is fixed to both sides of the mass pendulum and moves synchronously with the displacement of the mass pendulum. It is used to reflect the split beam back to the detector group to form a differential optical path detection mechanism. Optionally, the reflectivity of the optical thin film 12 is not less than 95%.

[0037] The servo control circuit includes a signal processing module, a feedback control module, and an actuator, which amplifies, filters, and processes the differential optical signal, generates control commands, drives the mass pendulum to return to the equilibrium position, and realizes closed-loop control.

[0038] The symmetrical beam splitting differential optical path structure can suppress the influence of light source intensity drift, ambient temperature fluctuation and mechanical vibration on the detection results, and significantly reduce the zero-bias drift and measurement noise of the sensor.

[0039] This accelerometer is suitable for applications that require high measurement accuracy and system stability, such as inertial navigation, precision space measurement, and earthquake monitoring.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A flexible accelerometer based on a symmetrical spectroscopic differential optical path, characterized in that, include: The base (1), mass pendulum (2), torque generator (3), servo control circuit (4), and symmetrical beam splitting differential optical path sensing unit (5); the symmetrical beam splitting differential optical path sensing unit (5) includes: light source (6), beam splitter (7), first focusing lens (8), second focusing lens (9), optical thin film (12), first photodetector group (10), and second photodetector group (11); The mass pendulum (2), light source (6), beam splitter (7), first focusing lens (8), second focusing lens (9), first photodetector group (10) and second photodetector group (11) are fixed on the base (1); The mass pendulum (2) adopts a symmetrical double flexible beam structure, and symmetrical optical films (12) are provided on the upper and lower surfaces of the far end of the flexible ribs of the mass pendulum (2). The light emitted by the light source (6) is split into two symmetrical beams by the beam splitter (7), and then shines on the optical thin films (12) on the upper and lower surfaces of the mass pendulum (2) through the first focusing lens (8) and the second focusing lens (9). The first photodetector group (10) and the second photodetector group (11) receive the light signals reflected by the optical thin films (12) on the upper and lower surfaces of the mass pendulum (2) and convert them into electrical signals to be sent to the servo control circuit (4). The servo control circuit (4) is used to obtain the change in differential light intensity ratio through the received electrical signal to obtain the displacement of the mass pendulum (2), and generate a control signal based on the displacement to drive the torque generator (3) so that the mass pendulum (2) returns to the initial position, thereby realizing closed-loop control.

2. The flexible accelerometer according to claim 1, characterized in that, The mass pendulum (2) is made of single-crystal silicon or quartz.

3. The flexible accelerometer according to claim 1, characterized in that, The light source (6) is a laser diode with an output wavelength in the visible or near-infrared band.

4. The flexible accelerometer according to claim 1, characterized in that, The beam splitter (7) is a beam splitter cube that splits the light emitted from the light source (6) into two beams of equal intensity and symmetrical direction.

5. The flexible accelerometer according to claim 1, characterized in that, The reflectivity of the optical thin film (12) is not less than 95%.

6. The flexible accelerometer according to claim 1, characterized in that, A collimating lens is provided in the light source (6).

7. The flexible accelerometer according to claim 1, characterized in that, The servo control circuit (4) is specifically used to amplify and filter the received electrical signals.

8. The flexible accelerometer according to claim 1, characterized in that, The base (1) is made of a material with high rigidity and low thermal expansion coefficient.

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