Method and system for testing angular vibration transmission characteristics of fiber-optic gyroscope inertial platform

Abstract

The application discloses a kind of optical fiber gyro inertial platform angular vibration transmission characteristic test methods, including synchronous acquisition position angular vibration table excitation angle signal and the frame angle signal of optical fiber gyro inertial platform;According to the frame angle signal of optical fiber gyro inertial platform, the method for obtaining optical fiber gyro inertial platform attitude angle signal is adopted navigation solution, and it is relevantly operated, and relevant characteristic function is obtained;According to the relevant characteristic function, the amplitude-phase characteristic solution of stable loop is carried out, and the amplitude of stable loop and the phase of stable loop in optical fiber gyro inertial platform are obtained;The application also discloses a kind of optical fiber gyro inertial platform angular vibration transmission characteristic test system, including position angular vibration table, optical fiber gyro inertial platform, optical fiber platform ground test system, position angular vibration table control cabinet and electric control box.The application can be applied to the transmission characteristic evaluation of optical fiber gyro inertial platform angular vibration, with higher accuracy and flexibility.

Description

Technical Field

[0001] This invention relates to a method for testing the angular vibration transmission characteristics of an inertial platform using a fiber optic gyroscope, belonging to the technical field of testing the dynamic angular transmission characteristics of inertial platforms. Background Technology

[0002] A fiber optic gyroscope inertial platform is an inertial navigation and measurement device that uses inertial sensors to measure the linear and angular motion parameters of a carrier relative to inertial space. The platform consists of a fiber optic gyroscope, an accelerometer, a platform body, a stabilization control loop, a support frame, and a base. The stabilization loop stabilizes the platform in inertial space, the fiber optic gyroscope measures the carrier's angular velocity, the accelerometer measures the carrier's linear acceleration, and Newton's second law is used to calculate the carrier's velocity and position.

[0003] The stabilization loop is the core control loop in a fiber optic gyroscope inertial platform. It consists of a fiber optic gyroscope, a controller, and a torque motor. The angular velocity, sensitive to the fiber optic gyroscope, is used by the controller to generate control interference to counteract the interference torque at the axis, thus stabilizing the platform in inertial space. The performance of the stabilization loop directly affects the accuracy of establishing the inertial coordinate system; therefore, it requires high control precision, good dynamic characteristics, and excellent signal transmission characteristics within its bandwidth.

[0004] Angular transfer characteristics are a method for detecting the control characteristics of a stable loop. An excitation signal is generated by an external angular vibration table. After passing through a stable platform, the angle measured by the platform frame and the output signal from the inertial instruments on the platform are analyzed. To accurately evaluate angular transfer characteristics, a high-precision testing method is particularly important. Currently, the commonly used method is to linearly fit the platform frame and remove the long-term trend of the angle signal as the platform's excited angle in the geographic frame. However, due to factors such as ground velocity and gyroscope drift, the nonlinear drift of the platform is significant. Therefore, this method is only suitable for short-time angular vibration and small-angle drift of the platform. There is an urgent need for a fiber optic gyroscope inertial platform angular vibration testing method that is not limited by the angular vibration time and drift angle range. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned defects and provide a method and system for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform. This invention overcomes the shortcomings of existing testing methods that use platform frame angle fitting approximation, which leads to large errors in evaluating the angular vibration transmission characteristics of the inertial platform. This invention can be applied to the evaluation of the angular vibration transmission characteristics of fiber optic gyroscope inertial platforms and provides a technical foundation for the development of new digital control loop systems.

[0006] To achieve the above-mentioned objectives, the present invention provides at least one of the following technical solutions:

[0007] A method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform includes:

[0008] The excitation angle signal of the position angle vibration table and the frame angle signal of the fiber optic gyroscope inertial platform are acquired simultaneously.

[0009] Based on the frame angle signal of the fiber optic gyroscope inertial platform, the attitude angle signal of the fiber optic gyroscope inertial platform is obtained by the navigation calculation method.

[0010] Correlation calculations were performed on the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table to obtain the correlation characteristic function;

[0011] The amplitude and phase characteristics of the stable loop are calculated based on the relevant characteristic functions to obtain the amplitude and phase of the stable loop in the fiber optic gyroscope inertial platform.

[0012] Furthermore, based on the frame angle signal of the fiber optic gyroscope inertial platform, the method for obtaining the attitude angle signal of the fiber optic gyroscope inertial platform using navigation calculation methods includes:

[0013] Based on the differential equations of the navigation attitude of the fiber optic gyroscope inertial platform, the platform's coordinate system is obtained using a navigation solution method. p To navigation coordinate system n Directional cosine array ;

[0014] The platform base system is obtained based on the frame angle signal of the fiber optic gyroscope inertial platform. b To the platform body coordinate system p Directional cosine array ;

[0015] according to and Get platform base system b To navigation coordinate system n Directional cosine array , ;

[0016] Will Representing the attitude angle signal of the fiber optic gyroscope inertial platform in matrix form and substituting it into... The attitude angle signal of the fiber optic gyroscope inertial platform is obtained.

[0017] The platform coordinate system p The origin is located at the center of the fiber optic gyroscope inertial platform, and the x, y, and z axes are along the X, Y, and Z sensitive axes of the fiber optic gyroscope inertial platform, respectively.

[0018] The platform base system b The origin is located at the center of mass of the fiber optic gyroscope inertial platform, and the x, y, and z axes are along the X, Y, and Z frame axes of the fiber optic gyroscope inertial platform, respectively.

[0019] Furthermore, navigation coordinate system n The North-Sky-East geographic coordinate system is adopted.

[0020] Furthermore, the differential equation for the navigation attitude of the fiber optic gyroscope inertial platform is as follows:

[0021] ;

[0022] in: Indicates the platform's coordinate system p Relative to the geocentric inertial coordinate system i The drift angular velocity; Representing the navigation coordinate system n Relative to the geocentric inertial coordinate system i angular velocity, ,in, For Earth's rotation in the navigation coordinate system n The projection below, Navigation coordinate system n The rotational angular rate generated by the Earth's rotation in the navigation coordinate system n The projection below;

[0023] Based on the differential equations of the navigation attitude of the fiber optic gyroscope inertial platform, the platform's coordinate system is obtained using a navigation solution method. p To navigation coordinate system n Directional cosine array The method is as follows:

[0024] Assume the fiber optic gyroscope inertial platform is in the navigation coordinate system n The initial values ​​of the azimuth, pitch, and roll angles are respectively ψ 0、 i 0 and c 0;

[0025] Will The initial value is represented as ψ 0、 i 0 and c A matrix of zeros is used to apply the differential equations of the navigation attitude of a fiber optic gyroscope inertial platform. Update the solution.

[0026] Furthermore, the platform base system is obtained based on the frame angle signal of the fiber optic gyroscope inertial platform. b To the platform body coordinate system p Directional cosine array The method is as follows:

[0027]

[0028] in, These are the servo frame angle signals, outer ring frame angle signals, inner ring frame angle signals, and platform frame angle signals of the fiber optic gyroscope inertial platform, respectively.

[0029] for The transpose of .

[0030] Furthermore, Representing the attitude angle signal of the fiber optic gyroscope inertial platform in matrix form and substituting it into... The method for obtaining the attitude angle signal of the fiber optic gyroscope inertial platform is as follows:

[0031] make ;

[0032] Will Represented in matrix form as the attitude angle signal of a fiber optic gyroscope inertial platform:

[0033] in, ψ b , i b and c b The fiber optic gyroscope inertial platform base is positioned in the navigation coordinate system. n The azimuth, pitch, and roll angles in the equation. ψ b , i b and c b That is, the attitude angle signal of the fiber optic gyroscope inertial platform;

[0034] This will be represented as a matrix of attitude angle signals from a fiber optic gyroscope inertial platform. Substitution The attitude angle signal of the fiber optic gyroscope inertial platform was obtained:

[0035] .

[0036] Furthermore, based on the stationarity analysis results of the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table, correlation calculations are performed on the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table to obtain the correlation characteristic function.

[0037] The stationarity analysis results of the attitude angle signal and the position angle vibration table excitation angle signal of the fiber optic gyroscope inertial platform show that they meet the wide stationarity condition. The specific method of stationarity analysis is as follows:

[0038] The attitude angle signal of the fiber optic gyroscope inertial platform is represented as a function. ;

[0039] The excitation angle signal of the position angle vibration table is expressed as a function. ;

[0040] in: Indicates frequency, t Indicates time; The initial phase is represented and follows a uniform distribution: ; The phase difference between the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table is the phase of the stable loop in the fiber optic gyroscope inertial platform, which is a fixed value after time synchronization. A , B They are respectively x (t), y The amplitude of (t), and They are respectively x (t), y Gaussian white noise in (t), and independent and identically distributed: , ;

[0041] calculate x mean of (t) and autocorrelation function :

[0042]

[0043]

[0044] ;

[0045] calculate y mean of (t) and autocorrelation function :

[0046]

[0047]

[0048] ;

[0049] in, The sampling time interval, and They are respectively x ( t white noise and signal y ( t The autocorrelation function of the signal white noise;

[0050] and The calculation result is zero, and and Only with the sampling time interval The attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table meet the wide stationarity condition.

[0051] Furthermore, the relevant characteristic functions include x The autocorrelation function of (t) , y The autocorrelation function of (t) and cross-correlation function :

[0052] .

[0053] Furthermore, the method for obtaining the amplitude and phase of the stable loop in the fiber optic gyroscope inertial platform by solving the amplitude and phase characteristics of the stable loop based on the relevant characteristic functions is as follows:

[0054] when , , ,

[0055] get , and expression , and :

[0056]

[0057]

[0058] ;

[0059] according to , and Obtain the amplitude of the stable loop in the fiber optic gyroscope inertial platform and stable loop phase :

[0060]

[0061]

[0062] in: , , and They represent x ( t )and y ( t The variance of the fluctuation; , , and It is obtained from the actual discrete data of the position angle vibration table excitation angle signal and the fiber optic gyroscope inertial platform attitude angle signal.

[0063] A fiber optic gyroscope inertial platform angular vibration transmission characteristic testing system is used for the above-mentioned fiber optic gyroscope inertial platform angular vibration transmission characteristic testing method, including a position angle vibration table, a fiber optic gyroscope inertial platform, a fiber optic platform ground testing system, a position angle vibration table control cabinet, and an electrical control box.

[0064] The position angle vibration table control cabinet is used to send control commands to the position angle vibration table;

[0065] The position angle vibration table receives control commands from the position angle vibration table control cabinet and generates the position angle vibration table excitation angle signal according to the control commands.

[0066] The fiber optic gyroscope inertial platform is installed above the position angle vibration table. Under the excitation of the excitation angle signal of the position angle vibration table, the frame angle signal of the fiber optic gyroscope inertial platform is generated.

[0067] The fiber optic platform ground testing system is used to acquire the frame angle signal of the fiber optic gyroscope inertial platform and send the flip level signal to the electrical control box.

[0068] The electrical control box receives the flip-level signal from the ground testing system of the fiber optic platform, and controls the position angle vibration table control cabinet to synchronously acquire the excitation angle signal of the position angle vibration table according to the flip-level signal.

[0069] Compared with the prior art, the present invention has the following advantages:

[0070] (1) The present invention uses navigation calculation and attitude conversion to obtain the accurate attitude of the platform body relative to the geographic system, which overcomes the limitation of the traditional method that requires the platform body to drift a small angle when using linear fitting of the platform frame, and the attitude measurement accuracy is higher.

[0071] (2) The correlation digital solution method for stationary random signals used in this invention is more flexible than the traditional solution method for the angular transfer characteristics of analog signals;

[0072] (3) The present invention uses a simple level trigger for time synchronization of position angle vibration table and platform signal acquisition, with small phase error;

[0073] (4) Based on the premise that both the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table meet the wide stability condition, this invention performs amplitude and phase characteristic calculation of the stable loop to obtain the amplitude and phase of the stable loop in the fiber optic gyroscope inertial platform, providing a technical basis for the development of a new digital control loop system. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the fiber optic gyroscope inertial platform angular vibration transmission characteristic testing system of the present invention;

[0075] Figure 2 This is a schematic diagram of the method for testing the angular vibration transmission characteristics of an fiber optic gyroscope inertial platform according to the present invention.

[0076] Figure 3 This is an embodiment of the present invention. oh The amplitude-frequency response diagram obtained when = 1 rad / s, where (a) is the signal comparison diagram and (b) is the local magnified diagram;

[0077] Figure 4 This is an embodiment of the present invention. oh The amplitude-frequency response diagram obtained when =10rad / s, where (a) is the signal comparison diagram and (b) is the local magnified diagram;

[0078] Figure 5 This is an embodiment of the present invention. oh The amplitude-frequency response diagram obtained when =20rad / s, where (a) is the signal comparison diagram and (b) is the local magnified diagram;

[0079] Figure 6 This is an embodiment of the present invention. oh The amplitude-frequency response diagram obtained at 30 rad / s, where (a) is a signal comparison diagram and (b) is a magnified view of a local area. Detailed Implementation

[0080] The features and advantages of the present invention will become clearer and more apparent from the following detailed description.

[0081] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0082] Angular vibration transmission characteristic testing is used to evaluate the tracking characteristics of the stable control loop of a fiber optic gyroscope platform to external excitation angular motion, and is a method for testing angular transmission characteristics. This invention provides a method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform, used to test the control transmission characteristics of the fiber optic gyroscope inertial platform under angular vibration conditions. This method first achieves data synchronization between the angle signal of the fiber optic gyroscope inertial platform frame and the excitation signal of the position angle vibration table by generating a data synchronization signal. Then, based on navigation calculation methods, the attitude of the platform base system relative to the geographic frame is obtained, resulting in the attitude angle signal of the fiber optic gyroscope inertial platform. x ( t Finally, the excitation signal is obtained through a diagonal vibration table. y( t ) and platform attitude angle signal x ( t Correlation analysis of two sets of stationary random signals and calculation of the amplitude and phase characteristics of the stable loop were used to evaluate the angular vibration transmission characteristics of the fiber optic gyroscope inertial platform. Experiments show that the stable loop amplitude accuracy of the fiber optic gyroscope inertial platform meets the system requirements of 0.02 dB and the phase angle accuracy meets 0.02°, solving the problem of accurately evaluating the angular dynamic transmission characteristics of a high-precision fiber optic gyroscope inertial platform.

[0083] Specifically, the present invention provides a method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform, comprising:

[0084] (1) Synchronous acquisition of excitation angle data of angular vibration table and angle data of platform frame.

[0085] (2) Navigation calculation of fiber optic gyroscope inertial platform: The attitude of the platform base frame relative to the geographic frame is obtained through navigation calculation, eliminating the influence of gyroscope and ground speed nonlinear drift in the flight navigation state of the inertial platform. The transformation method is as follows:

[0086]

[0087] Transition matrix from platform base to platform body The transition matrix from the platform body to the geographic system is obtained by substituting the platform frame angle data into the calculation. The following results were obtained by solving the navigation attitude differential equations of the fiber optic gyroscope inertial platform:

[0088]

[0089] Solve Obtain the three corners from the platform base to the geographic system. , and These three angles are the attitude angles output by the platform's angular vibration transmission, also referred to in this invention as the fiber optic gyroscope inertial platform attitude angle signals. x ( t ).

[0090] (3) Correlation analysis of stationary random signals: excitation angle signal of position angle vibration table y ( t ) and platform attitude angle signal x ( t The method for performing stationarity analysis is as follows:

[0091] ①The first moment of the platform attitude angle random signal is as follows:

[0092]

[0093]

[0094] ②The first moment of the random signal of the excitation angle of the position angle vibration table is as follows:

[0095]

[0096]

[0097] ③ The autocorrelation function of the two signals is a second-order moment operation:

[0098]

[0099]

[0100] The mean of the two random angle signals is zero. and Only its sampling time interval It is relevant and meets the broad stability condition.

[0101] (4) Calculation of amplitude and phase characteristics of stable loop: based on platform attitude angle signal x (t) and position angle vibration table excitation angle signal y The method for calculating the amplitude and phase characteristics of the steady-state loop based on the relevant characteristics of (t) is as follows:

[0102] For platform attitude angle signal x (t) and position angle vibration table excitation angle signal y The autocorrelation and cross-correlation functions of (t):

[0103]

[0104]

[0105]

[0106] when That is, when the sampling time interval is 0, , We can obtain:

[0107]

[0108]

[0109]

[0110] in: and These represent the platform attitude angle signals. x ( t ) and position angle vibration table excitation angle signaly ( t The variance of the fluctuation is obtained by, respectively through , , The actual data of the excitation angle of the vibration table and the position angle were calculated.

[0111] Therefore, the amplitude and phase of the stable loop are respectively:

[0112]

[0113]

[0114] in: , .

[0115] example:

[0116] This embodiment employs a method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform: an angular rate excitation table provides the angular velocity, and external level triggering synchronizes the data between the platform and the angular vibration table; based on the frame angle signal measured by the fiber optic gyroscope inertial platform, the attitude of the platform base system relative to the geographic frame is obtained using a navigation calculation method; stationarity analysis is performed on the angular vibration table excitation signal and the platform attitude angle signal, and the transmission characteristics of amplitude and phase between the angular vibration table and the inertial platform during low-frequency angular vibration are obtained through correlation calculation of the two signals and amplitude-phase characteristic calculation of the stable loop. Although this embodiment only tests low-frequency angular vibration, the method of this invention is equally applicable to the testing of high-frequency angular vibration.

[0117] The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform in this embodiment includes the following steps:

[0118] (1) Synchronous acquisition of the excitation angle signal of the position angle vibration table and the frame angle signal of the fiber optic gyroscope inertial platform

[0119] according to Figure 1 A fiber optic gyroscope platform angular vibration testing system was constructed, comprising a position angular vibration table, a fiber optic gyroscope inertial platform, a fiber optic platform ground testing system, a position angular vibration table control cabinet, and an electrical control box. The fiber optic gyroscope inertial platform is mounted on the position angular vibration table, which is connected to the electrical control box via an adapter cable and a slip ring. The electrical control box is then connected to the fiber optic platform ground testing system via a cable. The electrical control box generates synchronization signals between the position angular vibration table and the inertial platform, synchronously acquiring the angular vibration excitation angle and the platform frame angle, thus reducing phase delay caused by signal acquisition equipment deviations.

[0120] During the test, the position angle vibration table control cabinet sends control commands to the position angle vibration table, generating angular motion signals with a frequency of 1–30 rad / s and an amplitude of 0.15°. The fiber optic platform ground test system control box sends a high-level signal as a data recording signal for itself and the position angle vibration table. Upon receiving this signal, the position angle vibration table control cabinet begins data storage. Simultaneously, the fiber optic platform ground test system records the frame angle signal of the fiber optic gyroscope inertial platform. When the angular vibration test ends, the fiber optic platform ground test system control box sends a low-level signal. Upon receiving this signal, the position angle vibration table control cabinet stops data acquisition, and the fiber optic platform ground test system also simultaneously ends data recording.

[0121] (2) Navigation calculation of fiber optic gyroscope inertial platform

[0122] according to Figure 2 The navigation calculation is performed according to the process shown, and the fiber optic gyroscope inertial platform maintains a stable spatial state throughout the navigation calculation process.

[0123] (2.1) Introduction to the coordinate system required for navigation solution process:

[0124] 1) Geocentric inertial coordinate system ( i Tie)--

[0125] The origin of the geocentric inertial coordinate system is located at the Earth's center. The axis is along the direction of the Earth's polar axis. , It lies within the Earth's equatorial plane and remains stationary relative to inertial space.

[0126] 2) Earth inertial coordinate system ( e Tie)--

[0127] The origin of the Earth's coordinate system is located at the Earth's center. The axis is along the direction of the Earth's polar axis. , Within the Earth's equatorial plane Pointing towards the Greenwich Meridian in the equatorial plane Pointing towards 90° East longitude.

[0128] 3) Navigation coordinate system ( n Tie)-- oNUE

[0129] A navigation coordinate system is a coordinate system selected as a navigation reference according to the needs of the navigation system during navigation. This invention selects the "North-Sky-East" geographic coordinate system as the navigation reference coordinate system.

[0130] 4) Platform coordinate system ( p Tie)--

[0131] The origin of the platform's coordinate system is located at the center of the fiber optic gyroscope inertial platform. The axis is along the X-axis of the platform's gyroscope sensing axis. The axis is along the Y-axis of the platform's gyroscope. The axis is along the Z-axis of the platform's gyroscope. After compensating for the drift errors of the three gyroscopes, the platform coordinate system is aligned with... i Department overlap.

[0132] 5) Platform base system ( b Tie)--

[0133] The origin of the platform base coordinate system is located at the platform's center of mass. The axis is along the X-axis of the platform frame. The axis is along the Y-axis of the platform frame. The axis is along the Z-frame axis of the platform. Without considering the installation position and errors of the platform base on the angular vibration table, the platform base system coincides with the geographic coordinate system when the turntable is stationary.

[0134] (2.2) Detailed process of navigation solution:

[0135] The attitude of the platform base frame relative to the geographic frame is obtained through navigation calculation, eliminating the influence of gyroscopic and ground speed nonlinear drift present in inertial platforms during flight navigation. This is achieved using a direction cosine matrix from the platform base frame to the platform body coordinate system. and the direction cosine matrix from the platform's body coordinate system to the geographic system The direction cosine matrix of the platform base system relative to the geographic coordinate system is obtained as follows:

[0136]

[0137] The solutions are as follows. and :

[0138] (2.2.1) The attitude differential equations for navigation of an inertial platform based on fiber optic gyroscopes are solved:

[0139]

[0140] in: The drift of the platform system relative to the geocentric inertial coordinate system, that is, the drift of the three gyroscopes relative to inertial space, can be obtained through the self-calibration of the inertial platform; express n System relative to i The rotation of the system, including the rotation of the navigation system caused by the Earth's rotation. The movement of the inertial navigation system near the Earth's surface is caused by the curvature of the Earth's surface. n System rotation That is, .

[0141] In the "North-Sky-East" geographical coordinate system,

[0142]

[0143]

[0144] In the formula: This is the Earth's rotational angular rate. L The local geographical latitude, R M This represents the radius of curvature of the meridian. R N Indicates the radius of curvature of the zonal loop. h Indicates altitude, v E Indicates eastward speed. v N Indicates northbound speed.

[0145] Let the initial values ​​of the platform's azimuth, pitch, and roll angles in the "North-Sky-East" geographic system be as follows: ψ 0、 i 0 and c 0. The initial attitude value is obtained from the initial alignment, that is, the initial attitude value needs to be the initial angle of the platform relative to the geographic system obtained from external sources or itself. The attitude matrix is ​​then calculated through navigation. Update The initial value calculation matrix can be represented as:

[0146]

[0147] (2.2.2) The platform consists of four frame corners The collected data yielded the direction cosine matrix of the platform base system relative to the platform body coordinate system. These are the follower shaft frame angle, outer ring shaft frame angle, inner ring shaft frame angle, and platform shaft frame angle, respectively. That is, the frame angle signal of the fiber optic gyroscope inertial platform.

[0148]

[0149] (2.2.3) Solve for the attitude angles of the platform base system relative to the geographic system:

[0150] Let the azimuth, pitch, and roll angles of the fiber optic gyroscope inertial platform base in the "North-East" geographic system be respectively... ψb , i b and c b ,but

[0151]

[0152] At the same time, let it be obtained Represented as:

[0153]

[0154] The solution yields the three angles of the platform base's attitude in the geographic frame:

[0155]

[0156] The above , and The three angles are the attitude angles output by the platform's angular vibration transmission, i.e., the attitude angle signals of the fiber optic gyroscope inertial platform.

[0157] (3) Correlation analysis of stationary random signals

[0158] according to Figure 2 Related analysis shows that the rotation of the position angular vibration table causes the frame of the fiber optic gyroscope inertial platform to rotate. Under the action of the interference torque at the shaft end, the platform body rotates relative to the inertial space; the fiber optic gyroscope will be sensitive to the angular velocity generated by the interference torque. Under the action of the stabilizing loop, the platform remains stable, while the frame corners of the platform exhibit excited fluctuations. Based on the frame corner signals of the fiber optic gyroscope inertial platform and the excitation signals of the position angle vibration table, the amplitude and phase characteristics of the stabilizing loop can be obtained using the amplitude and phase calculation method based on correlation.

[0159] (3.1) Representation of attitude angle signal of fiber optic gyroscope inertial platform:

[0160] Let the attitude angle signal of the fiber optic gyroscope inertial platform be... x (t), the excitation angle signal of the position angle vibration table is y (t), specifically , , Each can be represented individually as x In the form of (t), the three attitude angles of the position angle vibration table can each be expressed individually as y The form (t) is used. These two random signals, with the same frequency but out of phase, are represented as follows:

[0161]

[0162]

[0163] in: Indicates frequency, t Indicates time; The initial phase is represented and follows a uniform distribution: The phase difference between the two signals is After time synchronization, the values ​​become fixed; A and B are respectively x (t), y (t) The deterministic amplitudes of the two signals, and They are respectively x (t), y Gaussian white noise in (t), and independent and identically distributed: , .

[0164] The amplitude and phase calculation of the control loop uses the correlation of two stationary random signals; the correlation function describes a certain moment. t instantaneous value and another moment The instantaneous values ​​are dependent on each other, therefore stationarity analysis of the two signals is required.

[0165] (3.2) Stationarity analysis shows:

[0166] Attitude angle signal of the platform base (attitude angle signal of the fiber optic gyroscope inertial platform) x The first moment of (t) is calculated as follows:

[0167]

[0168]

[0169]

[0170] Its autocorrelation function is a second-order moment operation:

[0171]

[0172] x ( t The noise component and the trigonometric function component in the signal are independent, therefore the second and third terms in the above equation are both 0, which leads to the following result:

[0173]

[0174] Similarly, the excitation angle signal of the position angle vibration table y The first moment of (t) is calculated as follows:

[0175]

[0176]

[0177] Its autocorrelation function is a second-order moment operation:

[0178]

[0179] The mean of the two random angle signals is zero. and Only its sampling time interval It is relevant and meets the broad stability condition.

[0180] For the platform base attitude angle signal x (t) and position angle vibration table excitation angle signal y The cross-correlation function of (t):

[0181]

[0182] Since the sine function and the noise part are independent of each other, and and Independent and identically distributed, therefore we have

[0183]

[0184] Ultimately, we can obtain:

[0185]

[0186] (4) Solution of amplitude and phase characteristics of stable loop

[0187] In proven x (t) and y (t) Under the premise of satisfying the wide stability condition, according to Figure 2 Correlation analysis was performed, and the amplitude and phase characteristics of the fiber optic gyroscope inertial platform loop were solved using the attitude angle information of the position angle vibration table and the platform. When the sampling time interval is zero, ,but , ,

[0188] From this we can obtain

[0189]

[0190]

[0191]

[0192] Therefore, the amplitude and phase relationship between the platform base attitude angle and the position angle vibration table excitation angle signal is obtained as follows:

[0193]

[0194]

[0195] in: , .

[0196] The above and That is, the amplitude and phase of the stable loop in the fiber optic gyroscope inertial platform.

[0197] Based on the stable loop amplitude and phase calculation method of correlation function, the dynamic transfer characteristics of the control loop angle of the fiber optic gyroscope inertial platform under low-frequency angular vibration conditions are obtained.

[0198] This embodiment uses the flip-level signal sent by the platform ground test system as the reference signal for synchronous recording with the angular vibration table control cabinet; the attitude of the platform base system relative to the geographic system is obtained based on the navigation calculation method, minimizing the amplitude and phase calculation errors in the angular transmission process; through the stationarity and correlation analysis of the platform attitude angle signal and the angular vibration table excitation angle signal, the amplitude and phase characteristics of the stable loop in the angular transmission are calculated.

[0199] This embodiment conducted tests on the fiber optic gyroscope inertial platform under four different operating conditions for each axis. The low-frequency angular vibration frequencies were 1 rad / s, 10 rad / s, 20 rad / s, and 30 rad / s, with an amplitude of 0.15°. Taking the X-axis angular vibration test as an example, the amplitude and phase characteristics of the stable loop during the low-frequency angular vibration of the X-axis under different operating conditions of the fiber optic gyroscope inertial platform are as follows: Figure 3 As shown in the figure. The dashed lines in the figure represent the platform base attitude angle signals obtained from the frame angle signals of the fiber optic gyroscope inertial platform. x ( t The solid line represents the position angle excitation angle signal of the vibration table. y ( t Different angular vibration frequencies are displayed using 3 to 4 cycles.

[0200] As can be seen, the platform base attitude angle x ( t ) and the excitation angle of the angular vibration table y ( t The curve amplitudes are basically the same. x ( t The phase lags slightly behind y ( t The calculated amplitude and phase of the three-axis stabilization loops of the fiber optic gyroscope inertial platform at different angular vibration frequencies are shown in Table 1.

[0201] Table 1 Results of platform amplitude and phase characteristics at low-frequency angular vibration frequency

[0202]

[0203] The test results show that the transmission characteristics of the platform's three axes can meet the requirements of amplitude accuracy of 0.02dB and phase accuracy of 0.02°.

[0204] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0205] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform, characterized in that, include: The excitation angle signal of the position angle vibration table and the frame angle signal of the fiber optic gyroscope inertial platform are acquired simultaneously. The attitude angle signal of the fiber optic gyroscope inertial platform is obtained based on the frame angle signal of the fiber optic gyroscope inertial platform. Correlation calculations were performed on the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table to obtain the correlation characteristic function; The amplitude and phase characteristics of the stable loop are calculated based on the relevant characteristic functions to obtain the amplitude and phase of the stable loop in the fiber optic gyroscope inertial platform. Methods for obtaining the attitude angle signal of a fiber optic gyroscope inertial platform based on its frame angle signal include: Based on the differential equation of attitude for navigation of the fiber optic gyroscope inertial platform, the platform coordinate system is obtained. p To navigation coordinate system n Directional cosine array ; The platform base system is obtained based on the frame angle signal of the fiber optic gyroscope inertial platform. b To the platform body coordinate system p Directional cosine array ; according to and Get platform base system b To navigation coordinate system n Directional cosine array , ; Will Representing the attitude angle signal of the fiber optic gyroscope inertial platform in matrix form and substituting it into... The attitude angle signal of the fiber optic gyroscope inertial platform is obtained. The platform coordinate system p The origin is located at the center of the fiber optic gyroscope inertial platform, and the x, y, and z axes are along the X, Y, and Z sensitive axes of the fiber optic gyroscope inertial platform, respectively. The platform base system b The origin is located at the center of mass of the fiber optic gyroscope inertial platform, and the x, y, and z axes are along the X, Y, and Z frame axes of the fiber optic gyroscope inertial platform, respectively.

2. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 1, characterized in that, Navigation coordinate system n The North-Sky-East geographic coordinate system is adopted.

3. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 2, characterized in that, The differential equation for the navigation attitude of a fiber optic gyroscope inertial platform is as follows: ； in: Indicates the platform's coordinate system p Relative to the geocentric inertial coordinate system i angular velocity of drift; Representing the navigation coordinate system n Relative to the geocentric inertial coordinate system i angular velocity, ,in, For Earth's rotation in the navigation coordinate system n The projection below, Navigation coordinate system n The rotational angular rate generated by the Earth's rotation in the navigation coordinate system n The projection below; Based on the differential equations of the navigation attitude of the fiber optic gyroscope inertial platform, the platform's coordinate system is obtained using a navigation solution method. p To navigation coordinate system n Directional cosine array The method is as follows: Assume the fiber optic gyroscope inertial platform is in the navigation coordinate system n The initial values ​​of the azimuth, pitch, and roll angles are respectively ψ 0、 θ 0 and γ 0; Will The initial value is represented as ψ 0、 θ 0 and γ A matrix of zeros is used to apply the differential equations of the navigation attitude of a fiber optic gyroscope inertial platform. Update the solution.

4. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 2, characterized in that, The platform base system is obtained based on the frame angle signal of the fiber optic gyroscope inertial platform. b To the platform body coordinate system p Directional cosine array The method is as follows: in, These are the servo frame angle signals, outer ring frame angle signals, inner ring frame angle signals, and platform frame angle signals of the fiber optic gyroscope inertial platform, respectively. for The transpose of .

5. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 2, characterized in that, Will Representing the attitude angle signal of the fiber optic gyroscope inertial platform in matrix form and substituting it into... The method for obtaining the attitude angle signal of the fiber optic gyroscope inertial platform is as follows: make ; Will Represented in matrix form as the attitude angle signal of a fiber optic gyroscope inertial platform: in, ψ b , θ b and γ b The fiber optic gyroscope inertial platform base is positioned in the navigation coordinate system. n The azimuth, pitch, and roll angles in the equation. ψ b , θ b and γ b That is, the attitude angle signal of the fiber optic gyroscope inertial platform; This will be represented as a matrix of attitude angle signals from a fiber optic gyroscope inertial platform. Substitution The attitude angle signal of the fiber optic gyroscope inertial platform was obtained: 。 6. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 1, characterized in that, Based on the stability analysis results of the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table, correlation calculations are performed on the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table to obtain the correlation characteristic function. The stationarity analysis results of the attitude angle signal and the position angle vibration table excitation angle signal of the fiber optic gyroscope inertial platform show that they meet the wide stationarity condition. The specific method of stationarity analysis is as follows: The attitude angle signal of the fiber optic gyroscope inertial platform is represented as a function. ; The excitation angle signal of the position angle vibration table is expressed as a function. ; in: Indicates frequency, t Indicates time; The initial phase is represented and follows a uniform distribution: ; The phase difference between the attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table is the phase of the stable loop in the fiber optic gyroscope inertial platform, which is a fixed value after time synchronization. A , B They are respectively x (t), y The amplitude of (t), and They are respectively x (t), y Gaussian white noise in (t), and independent and identically distributed: , ; calculate x mean of (t) and autocorrelation function : ； calculate y mean of (t) and autocorrelation function : ； in, The sampling time interval, and They are respectively x (t) signal white noise and y (t) Autocorrelation function of white noise in the signal; and The calculation result is zero, and and Only with the sampling time interval The attitude angle signal of the fiber optic gyroscope inertial platform and the excitation angle signal of the position angle vibration table meet the wide stationarity condition.

7. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 6, characterized in that, Relevant characteristic functions include x The autocorrelation function of (t) , y The autocorrelation function of (t) and cross-correlation function : 。 8. The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to claim 7, characterized in that, The method for calculating the amplitude and phase of the stable loop in a fiber optic gyroscope inertial platform based on relevant characteristic functions is as follows: when , , , get , and expression , and : ； according to , and Obtain the amplitude of the stable loop in the fiber optic gyroscope inertial platform and stable loop phase : in: , , and They represent x ( t )and y ( t The variance of the fluctuation; , , and It is obtained from the actual discrete data of the position angle vibration table excitation angle signal and the fiber optic gyroscope inertial platform attitude angle signal.

9. A test system for the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform, characterized in that, The method for testing the angular vibration transmission characteristics of a fiber optic gyroscope inertial platform according to any one of claims 1-8 includes a position angular vibration table, a fiber optic gyroscope inertial platform, a fiber optic platform ground testing system, a position angular vibration table control cabinet, and an electrical control box. The position angle vibration table control cabinet is used to send control commands to the position angle vibration table; The position angle vibration table receives control commands from the position angle vibration table control cabinet and generates the position angle vibration table excitation angle signal according to the control commands. The fiber optic gyroscope inertial platform is installed above the position angle vibration table. Under the excitation of the excitation angle signal of the position angle vibration table, the frame angle signal of the fiber optic gyroscope inertial platform is generated. The fiber optic platform ground testing system is used to acquire the frame angle signal of the fiber optic gyroscope inertial platform and send the flip level signal to the electrical control box. The electrical control box receives the flip-level signal from the ground testing system of the fiber optic platform, and controls the position angle vibration table control cabinet to synchronously acquire the excitation angle signal of the position angle vibration table according to the flip-level signal.

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