Multi-frequency rotation modulation optical gyroscope angle measurement system
By combining a single-axis optical gyroscope with a rotating micro-motion mechanism, the multi-frequency rotation modulation technology solves the problems of temperature drift dispersion and navigation error accumulation of optical gyroscope devices in traditional strapdown inertial navigation systems, and realizes high-precision three-axis angular rate measurement and drift error suppression.
Patent Information
- Application Number
- CN202511677425.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-01-09
AI Technical Summary
In traditional strapdown inertial navigation systems, the temperature drift dispersion of optical gyroscopes leads to nonlinear residuals in the compensation model, which are difficult to fully compensate for in dynamic environments. Furthermore, the drift component in the rotation axis direction cannot be modulated by rotation, resulting in the accumulation and divergence of navigation errors.
A single-axis optical gyroscope is used in combination with a rotation mechanism and a micro-motion mechanism. Through multi-frequency rotation modulation technology, the periodic circular motion and high-frequency sinusoidal angular vibration of the optical gyroscope's sensitive axis are realized. Combined with a signal processing unit, real-time demodulation and error correction are performed to separate and suppress constant zero bias and time-varying drift errors.
It achieves high-precision measurement of spatial three-axis angular rate, reduces the number of optical gyroscope sensors, lowers system cost, size and power consumption, and effectively suppresses two-axis drift errors, thereby improving navigation accuracy.
Smart Images
Figure CN121297829A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of inertial navigation and angle measurement technology, specifically to a multi-frequency rotation modulation optical gyroscope angle measurement system, which is suitable for applications such as spacecraft, ships, and drones that require high-precision attitude control and are sensitive to cost and space constraints. Background Technology
[0002] An optical gyroscope (fiber optic gyroscope or laser gyroscope) is an optical inertial sensor based on the Sagnac effect. By fixing the optical gyroscope to the mounting plane of the measured vehicle and ensuring that its sensitive axis is parallel to the rotation axis of the measured vehicle, the angular rate of rotation of the vehicle relative to inertial space can be effectively measured. Traditional strapdown inertial navigation systems typically rely on three optical gyroscopes with orthogonal axes to measure spatial attitude angles.
[0003] In terms of random error suppression, strapdown inertial navigation systems can typically suppress zero-bias drift in the direction perpendicular to the rotation axis through rotation modulation techniques. However, the drift component in the rotation axis direction cannot be modulated, leading to the accumulation and divergence of navigation errors. The temperature drift dispersion of multiple optical gyroscopes results in nonlinear residuals in the compensation model, which are uncontrollable in dynamic environments and difficult to fully compensate through calibration. Summary of the Invention
[0004] The purpose of this invention is to provide a multi-frequency rotation modulation optical gyroscope angle measurement system. Through the innovation of the single-axis optical gyroscope mounting structure and the real-time demodulation separation and error correction calculation of the angular rate by the signal processing unit, it can effectively realize the spatial three-axis angular rate calculation and the synchronous suppression of the drift error of the two axes.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a multi-frequency rotation modulation optical gyroscope angle measurement system, including a base mounted on the carrier under test, and a rotation mechanism, a micro-motion mechanism, an optical gyroscope and a signal processing unit mounted on the base. The optical gyroscope is mounted on the end face of the rotation mechanism in an inclined manner, and the sensitive axis of the optical gyroscope is in the XOZ plane and forms a 45° angle with the Z axis. The rotating mechanism is used to drive the optical gyroscope to rotate around the Z-axis relative to the base, so that the projection component of the gyroscope's sensitive axis in the XOY plane exhibits periodic circular motion. The micro-motion mechanism is used to drive the optical gyroscope to generate a high-frequency sinusoidal angular vibration in the Z-axis rotation direction on the basis of rotation, and to perform spectral shifting on the XOY plane signal; The optical gyroscope measurement model based on the superposition of the rotation mechanism and the micro-motion mechanism is as follows: ; in, The measured carrier is relative to the output of the optical gyroscope. Angular rate; The time-varying direction vector of the optical gyroscope's sensing axis; For the relative of the tested carrier The angular velocity of the system; The drift is constant with zero bias. This is time-varying drift; The signal processing unit acquires the output pulses of the optical gyroscope in real time and performs the following operations: Error correction is performed on the optical gyroscope measurement model to obtain the correction value; The correction values are demodulated and separated along three axes to obtain the angular rates of carrier attitude change in three directions. The error is iteratively updated based on the angular rate of carrier attitude change along three axes.
[0006] Preferably, the fundamental frequency rotation matrix of the optical gyroscope driven by the rotating mechanism is: ; in, It represents the fundamental frequency rotational angular rate.
[0007] Preferably, the high-frequency sinusoidal angular vibration signal is in the form of: ; in, This represents the amplitude of high-frequency angular vibration, and ; It is the angular frequency of high-frequency angular vibration, and has .
[0008] Preferably, the actual rotation angle of the optical gyroscope's sensing axis in the XOY plane after being driven by the superimposed rotation mechanism and the micro-motion mechanism becomes: ; The time-varying direction vector of the optical gyroscope's sensing axis is: ; in, This refers to the direction vector of the initial state of the sensitive axis of the optical gyroscope. .
[0009] Preferably, error correction is performed on the optical gyroscope measurement model, including: Let the Earth's rotation angular rate vector be: ; in, The latitude of the measured carrier; This represents the numerical value of the Earth's rotational angular rate. Let the angular rate vector of the attitude change of the measured carrier be: ; Ignoring the effects of the movement of the measured carrier on the Earth's surface If the rotational angular velocity is constant, then the relative velocity of the carrier... The angular velocity of the system can be decomposed into: ; Simultaneously, by performing a small-angle approximation on the high-frequency vibration, the corrected values for the optical gyroscope measurement model are obtained as follows: ; in, This is the projection component of the Earth's rotation angular rate along the sensitive axis of the optical gyroscope; To deduct The corrected value of the optical gyroscope measurement model after the error corresponds to the projected component of the carrier attitude change angular rate.
[0010] Preferably, the triaxial signal demodulation and separation includes: Z-axis demodulation: Correction value for optical gyroscope measurement model After extraction by a low-pass filter, the gain is amplified to obtain the filtered Z-axis motion angular rate of the carrier. ; Y-axis demodulation: Correction value for optical gyroscope measurement model A quadrature demodulated signal is applied, then bandpass filtered, and the filtered result is demodulated a second time. After low-pass filtering, the Y-axis motion angular rate of the carrier is obtained. ; The demodulation process in the X-axis direction is the same as that in the Y-axis direction. The angular rates of carrier attitude change along three axes were separated: .
[0011] Preferably, during demodulation in the Z-axis direction, the correction value The Z-axis motion angular velocity of the carrier is obtained by filtering using a low-pass filter LPF1: ; in, This is the Laplace operator for low-pass filtering, and its corresponding low-pass filter LPF1 cutoff frequency. ; In Y-axis demodulation, the correction value Applying a quadrature demodulated signal and filtering it using a bandpass filter (BPF) yields: ; in, The center frequency is A bandpass filter (BPF); A second demodulation is applied to the filtered result, and filtering is performed based on the low-pass filter LPF2 to obtain the Y-axis motion angular rate of the carrier. : ; in, For low-pass filtering, use the Laplace operator, with the corresponding cutoff frequency set to... .
[0012] Preferably, the iterative update specifically includes: The differential equation for the attitude matrix of the carrier is: ; The angular rates of attitude change of the separated three axial carriers Substituting these values into the attitude matrix differential equation, the real-time updated attitude matrix is calculated. ; attitude matrix Substituting these values into the error correction process yields the updated correction values for the optical gyroscope measurement model. Beneficial effects
[0013] (1) This invention combines a single optical gyroscope with a rotating mechanism and a micro-motion mechanism in an innovative way, and combines it with composite multi-frequency rotation modulation technology. By using a single-axis optical gyroscope, the spatial three-axis angular rate measurement signal can be separated and decoupled. Compared with the traditional three-axis measurement scheme of IMU, the number of optical gyroscope sensors is reduced from 3 to 1, and the system cost, volume and power consumption are greatly reduced.
[0014] (2) This invention can simultaneously and effectively achieve spatial triaxial angular rate calculation and synchronous suppression of drift errors in two axes; during demodulation in the X and Y axes, constant zero-bias drift is achieved. and time-varying drift The components were originally in the DC and low-frequency bands; after quadrature demodulation, they were shifted to... The frequency band is filtered out by a bandpass filter; while signal separation and demodulation in the X and Y axes are performed, drift error is completely suppressed; and during Z-axis signal demodulation, constant zero-bias drift can be effectively measured through an initialization calibration method. For time-varying drift The low-pass filter filters out the high-frequency part, and since the remaining low-frequency part can be modeled and compensated by the temperature model of the single-axis optical gyroscope system, the Z-axis drift error is partially suppressed. Attached Figure Description
[0015] Figure 1 This is a structural diagram of the multi-frequency rotation modulation optical gyroscope angle measurement system of the present invention; Figure 2 This is a diagram showing the initial working state of the multi-frequency rotation modulation optical gyroscope angle measurement system of the present invention; Figure 3This is a flowchart of the three-axis signal demodulation and separation and Earth rotation error iterative correction algorithm of the present invention; The diagram is labeled as follows: 1. Base; 2. Rotation mechanism; 3. Micro-motion mechanism; 4. Optical gyroscope; 5. Signal processing unit. Detailed Implementation
[0016] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of this invention and does not strictly limit the scope of protection specifically claimed by this invention.
[0017] The technical solution adopted in this invention is as follows: Figure 1 As shown, a multi-frequency rotation modulation optical gyroscope angle measurement system includes a base 1 mounted on the carrier under test, and a rotation mechanism 2, a micro-motion mechanism 3, an optical gyroscope 4, and a signal processing unit 5 mounted on the base. The optical gyroscope 4 is mounted at an angle on the end face of the rotation mechanism 2, and the sensitive axis of the optical gyroscope 4 is located in the XOZ plane and forms a 45° angle with the Z-axis. The rotation mechanism 2 drives the optical gyroscope 4 to rotate relative to the base around the Z-axis, so that the projection component of the gyroscope's sensitive axis in the XOY plane exhibits periodic circular motion. The micro-motion mechanism 3 drives the optical gyroscope 4 to generate a high-frequency sinusoidal angular vibration in the Z-axis rotation direction based on the rotation, thereby shifting the XOY plane signal spectrum. For the micro-motion mechanism 3, it can be selected based on... The micro-motion mechanism of the piezoelectric ceramic torque actuator drives the optical gyroscope system to generate micro-amplitude, high-frequency angular vibrations. The piezoelectric ceramic torque actuator works on the principle of the inverse piezoelectric effect. By applying an alternating voltage to four sets of symmetrically arranged piezoelectric ceramic stacks, it causes high-frequency micro-deformation (expansion and contraction), and then converts the linear displacement into pure torque output around the axis through an elastic hinge transmission mechanism. This mechanism has the characteristics of no mechanical backlash, fast response speed (down to millisecond level), high resolution (arcsecond level), and essentially no electromagnetic interference. It can effectively drive the optical gyroscope load to generate high-frequency angular vibrations that meet the theoretical requirements. The signal processing unit collects the gyroscope output pulses in real time and performs signal processing to complete angular rate demodulation separation and error correction calculation.
[0018] refer to Figure 2 The diagram shown is the initial working state diagram of the multi-frequency rotation modulation optical gyroscope 4-angle measurement system; assuming the initial state of the carrier is... System and If the axes coincide, then the initial direction vector of the four sensitive axes of the optical gyroscope is: ; For the fundamental frequency rotation of rotating mechanism 2, the fundamental frequency rotation matrix is: ; in, The fundamental frequency rotational angular rate; For the high-frequency vibration controlled by the micro-motion mechanism 3, the high-frequency sinusoidal vibration signal is as follows: ; in, The amplitude of the high-frequency angular vibration (unit: radians) and ; It is the angular frequency of high-frequency angular vibration, and has ; The actual rotation angle of the sensitive axis of the optical gyroscope 4 in the XOY plane after being driven by the superposition of the rotation mechanism 2 and the micro-motion mechanism 3 becomes: ; The time-varying direction vector of the 4-sensor axis of the optical gyroscope is: ; Therefore, the measurement model of the superimposed optical gyroscope 4 is as follows: ; in, The measured carrier is output by the optical gyroscope 4. Angular rate; This refers to the time-varying direction vector of the four sensitive axes of the optical gyroscope. For the relative of the tested carrier The angular velocity of the system; The drift is constant with zero bias. This is time-varying drift; Based on the above-described superimposed optical gyroscope 4 measurement model, refer to Figure 3 As shown, the signal processing unit performs the following operations: Error correction was performed on the measurement model of optical gyroscope 4 to obtain the correction value; Let the Earth's rotation angular rate vector be: ; Where L is the latitude of the measured carrier; This represents the numerical value of the Earth's rotational angular rate. Let the angular rate vector of the attitude change of the measured carrier be: ; Ignoring the effects of the movement of the measured carrier on the Earth's surface If the rotational angular velocity is constant, then the relative velocity of the carrier... The angular velocity of the system can be decomposed into: ; Simultaneously, a small-angle approximation operation is performed on the high-frequency vibration to obtain the correction value for the optical gyroscope 4 measurement model: ; in, This is the projection component of the Earth's rotation angular rate onto the 4-sensor axis of the optical gyroscope; To deduct The error correction value of the optical gyroscope 4 measurement model corresponds to the projection component of the carrier attitude change angular rate. The correction values of the optical gyroscope 4 measurement model are demodulated and separated along three axes to obtain the angular rates of carrier attitude change in three axes. Specifically, it includes: Z-axis demodulation: utilizing The time domain exhibits constant characteristics, and the values are corrected by adjusting the measurement model of the optical gyroscope 4. After extraction by a low-pass filter, the gain is amplified. ; in It is the Z-axis motion angular velocity of the carrier obtained after filtering; This represents the Laplace operator for low-pass filtering, and the corresponding cutoff frequency of the low-pass filter LPF1. (Can be set to) In this embodiment ); where constant zero bias drift Measurements can be calibrated under static conditions during the system initialization phase; Y-axis demodulation: Correction value for optical gyroscope 4 measurement model Applying a quadrature demodulated signal and then passing it through a bandpass filter yields: ; in The center frequency is A narrow-bandwidth bandpass filter (BPF) is used; after applying secondary demodulation to the filtering result and then performing low-pass filtering based on a low-pass filter (LPF2), the angular velocity of the carrier's Y-axis motion can be obtained. ; in, It is the Y-axis motion angular velocity of the carrier obtained by low-pass filtering; This represents the low-pass filter Laplace operator, and the cutoff frequency of its corresponding low-pass filter LPF2 can be set to... In this embodiment ; The demodulation process in the X-axis direction is the same as that in the Y-axis direction; similarly, the demodulation process in the X-axis direction can be obtained as follows: ; .
[0019] The error is iteratively updated based on the angular rate of carrier attitude change along three axes, including: The differential equation for the attitude matrix of the carrier is: ; And it is known that the attitude matrix of the carrier in its initial state is Then, based on the actual angular velocity of the carrier separated by the above real-time demodulation and filtering, Substituting into the differential equation of the attitude matrix, the real-time updated attitude matrix is calculated. ; attitude matrix Substitution During the calculation process, the correction values for the optical gyroscope 4 measurement model can be obtained. This is then used for the triaxial signal demodulation and separation calculations mentioned above; attitude matrix Substituting the values into the error correction process, we obtain the updated correction values for the optical gyroscope 4 measurement model.
[0020] The embodiments of the present invention have been described in detail above with reference to the examples. However, the present invention is not limited to the above embodiments. For those skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.
Claims
1. A multi-frequency rotational modulation optical gyroscope angle measurement system, characterized in that, It includes a base mounted on the carrier under test, and a rotating mechanism, a micro-motion mechanism, an optical gyroscope and a signal processing unit mounted on the base. The optical gyroscope is mounted at an angle on the end face of the rotating mechanism, and the sensitive axis of the optical gyroscope is in the XOZ plane and forms a 45° angle with the Z axis. The rotating mechanism is used to drive the optical gyroscope to rotate around the Z-axis relative to the base, so that the projection component of the gyroscope's sensitive axis in the XOY plane exhibits periodic circular motion. The micro-motion mechanism is used to drive the optical gyroscope to generate a high-frequency sinusoidal angular vibration in the Z-axis rotation direction on the basis of rotation, and to perform spectral shifting on the XOY plane signal; The optical gyroscope measurement model based on the superposition of the rotation mechanism and the micro-motion mechanism is as follows: ； in, The measured carrier is relative to the output of the optical gyroscope. Angular rate; The time-varying direction vector of the optical gyroscope's sensing axis; For the relative of the tested carrier The angular velocity of the system; The drift is constant with zero bias. This is time-varying drift; The signal processing unit acquires the output pulses of the optical gyroscope in real time and performs the following operations: Error correction is performed on the optical gyroscope measurement model to obtain the correction value; The correction values are demodulated and separated along three axes to obtain the angular rates of carrier attitude change in three directions. The error is iteratively updated based on the angular rate of carrier attitude change along three axes.
2. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 1, characterized in that: The fundamental frequency rotation matrix of the optical gyroscope driven by the rotating mechanism is: ； in, It represents the fundamental frequency rotational angular rate.
3. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 2, characterized in that: The high-frequency sinusoidal angle vibration signal is in the form of: ； in, This represents the amplitude of high-frequency angular vibration, and ; It is the angular frequency of high-frequency angular vibration, and has .
4. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 3, characterized in that: The actual rotation angle of the optical gyroscope's sensing axis in the XOY plane after being driven by the superposition of the rotation mechanism and the micro-motion mechanism becomes: ； The time-varying direction vector of the optical gyroscope's sensing axis is: ； Where S is the direction vector of the initial state of the optical gyroscope's sensitive axis; .
5. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 4, characterized in that: Error correction for optical gyroscope measurement models includes: Let the Earth's rotation angular rate vector be: ； in, The latitude of the measured carrier; This represents the numerical value of the Earth's rotational angular rate. Let the angular rate vector of the attitude change of the measured carrier be: ； Ignoring the effects of the movement of the measured carrier on the Earth's surface If the rotational angular velocity is constant, then the relative velocity of the carrier... The angular velocity of the system can be decomposed into: ； Simultaneously, by approximating the high-frequency vibration, the corrected values for the optical gyroscope measurement model are obtained as follows: ； in, This is the projection component of the Earth's rotation angular rate along the sensitive axis of the optical gyroscope; To deduct The corrected value of the optical gyroscope measurement model after the error corresponds to the projected component of the carrier attitude change angular rate.
6. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 5, characterized in that: The triaxial signal demodulation and separation includes: Z-axis demodulation: Correction value for optical gyroscope measurement model After extraction by a low-pass filter, the gain is amplified to obtain the filtered Z-axis motion angular rate of the carrier. ; Y-axis demodulation: Correction value for optical gyroscope measurement model A quadrature demodulated signal is applied, then bandpass filtered, and the filtered result is demodulated a second time. After low-pass filtering, the Y-axis motion angular rate of the carrier is obtained. ; The demodulation process in the X-axis direction is the same as that in the Y-axis direction. The angular rates of carrier attitude change along three axes were separated: .
7. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 6, characterized in that: During the demodulation process in the Z-axis direction, filtering is performed based on the low-pass filter LPF1 to obtain the Z-axis motion angular velocity of the carrier: ； in, This is the Laplace operator for low-pass filtering, and its corresponding low-pass filter LPF1 cutoff frequency. ; In the Y-axis demodulation, filtering based on a bandpass filter (BPF) yields: ； in, The center frequency is A bandpass filter (BPF); A second demodulation is applied to the filtered result, and filtering is performed based on the low-pass filter LPF2 to obtain the Y-axis motion angular rate of the carrier. : ； in, This is a low-pass filter Laplace operator, and its corresponding low-pass filter LPF1 cutoff frequency is set to... .
8. The multi-frequency rotation modulation optical gyroscope angle measurement system according to claim 1, characterized in that: The iterative update specifically refers to: The differential equation for the attitude matrix of the carrier is: ; The angular rates of carrier attitude change along three axes will be separated. Substituting these values into the differential equation of the attitude matrix, the real-time updated attitude matrix is calculated. ; attitude matrix Substituting the values into the error correction process, we obtain the updated correction values for the optical gyroscope measurement model.