SINS / CNS deep combination navigation method and system thereof

Abstract

This invention discloses a SINS / CNS deep integrated navigation method and system. By introducing star sensor angular velocity information measured by the SINS gyroscope, a separate star centroid tracking channel filter is designed for each star. The star centroid is extracted within the range of the predicted star position, and a Kalman filtering algorithm is used to obtain high-precision star centroid coordinate estimation results. Simultaneously, based on the estimation mean square error matrix of the tracking channel filter, the measurement noise covariance matrix of the integrated navigation filter is adaptively adjusted to improve the navigation performance of the integrated navigation system under strong noise conditions.

Description

Technical Field

[0001] This invention relates to the field of inertial / astronomical integrated navigation technology, and more specifically to a SINS / CNS deep integrated navigation method and system. Background Technology

[0002] Strapdown Inertial Navigation Subsystem (SINS) is a fully autonomous navigation technology with advantages such as high short-term accuracy, continuous output, strong anti-interference capability, and complete navigation information. However, its navigation error accumulates over time, making it difficult to operate independently for extended periods. It needs to be combined with other navigation systems to improve navigation performance. Celestial Navigation Subsystem (CNS) uses star sensors to observe stars and determine the carrier's navigation parameters. It is highly stealthy, autonomous, and has no accumulated error, providing high-precision attitude and position information. However, it also suffers from drawbacks such as discontinuous output information and susceptibility to weather conditions. Since SINS and CNS each have their own advantages and disadvantages, combining them for integrated navigation can achieve complementary benefits.

[0003] In existing SINS / CNS tightly integrated navigation methods, CNS obtains the centroid coordinates of the direct and refracted stars using a star centroid extraction algorithm, and further calculates the apparent altitude of the refracted star. Simultaneously, the attitude and position information output by SINS is used to estimate the centroid coordinates of the direct star and the apparent altitude of the refracted star. Then, the difference between the centroid coordinates of the direct star and the difference between the apparent altitudes of the refracted star output by SINS and CNS are used as measurement inputs to the integrated navigation filter, where the Kalman filtering algorithm is used to estimate and compensate for the errors of the inertial navigation subsystem. This approach has the following drawbacks:

[0004] (1) The centroid coordinates of the star points are calculated only by the star point centroid extraction algorithm. Due to the influence of factors such as sky background radiation and star sensor noise, the signal-to-noise ratio of the star map is reduced, which will lead to an increase in the star point centroid extraction error, thereby causing a decrease in the navigation accuracy of the combined system.

[0005] (2) In a tightly coupled system, the measurement information of each star is weighted equally. In reality, due to the different magnitudes and star map noise of each star, the accuracy of the measurement information of each star is different. Using the same weight will lead to a decrease in the navigation accuracy of the coupled system in a low signal-to-noise ratio environment.

[0006] (3) When extracting the centroid of stars, the star sensor needs to perform a traversal scan and threshold segmentation of the entire star map to separate the stars from the background. Therefore, the star centroid extraction process of the compact combination system takes a long time, which affects the real-time performance of the system.

[0007] Therefore, how to provide a high-precision, real-time-performance SINS / CNS deep integrated navigation method and system is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a SINS / CNS deep integrated navigation method and system. This invention introduces star sensor angular velocity information measured by the SINS gyroscope, designs a separate star centroid tracking channel filter for each star, extracts the star centroid within the range of the predicted star position, and uses the Kalman filtering algorithm to obtain high-precision star centroid coordinate estimation results. Simultaneously, based on the estimation mean square error matrix of the tracking channel filter, the measurement noise covariance matrix of the integrated navigation filter is adaptively adjusted to improve the navigation performance of the integrated navigation system under strong noise conditions.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A deep integrated navigation method using SINS / CNS, based on the inertial navigation subsystem (SINS) and the celestial navigation subsystem (CNS), includes the following steps:

[0011] S1. Based on the angular velocity information measured by the SINS gyroscope, establish the state equation of the tracking channel filter for each star;

[0012] S2. Based on the state equation of the tracking channel filter, for t k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point.

[0013] S3. The measured value of the centroid coordinates of the star point is used as a quantity. The quantity is sent to the tracking channel filter to estimate the estimated value of the centroid coordinates of the star point and the corresponding estimated mean square error matrix.

[0014] S4. Based on the estimated centroid coordinates of the star points output by the tracking channel filter, distinguish between direct stars and refracted stars, and establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation, and refracted star measurement equation respectively.

[0015] S5. The SINS / CNS deep integrated navigation state equation is used to update the time of the SINS / CNS deep integrated navigation filter. The direct star measurement equation and the refracted star measurement equation are used to update the measurement of the SINS / CNS deep integrated navigation filter. The mean square error matrix is ​​estimated as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter. The information of the inertial navigation subsystem and the astronomical navigation subsystem is fused, and the corrected navigation information is output.

[0016] Preferably, the specific content of S1 includes:

[0017] Using the star's center-of-mass coordinates u, v and the gyroscope's constant drift ε x ,ε y ,ε z To track the state variable X of the channel filter c The state equation for the tracking channel filter is established as follows:

[0018]

[0019] In the formula:

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] X c =[uv ε x ε y ε z ] T

[0026]

[0027]

[0028]

[0029] Where f is the focal length of the star sensor; The mounting matrix for the star sensor; The angular rate output by the SINS gyroscope; w gx ,w gy ,w gz This refers to the random measurement error of the SINS gyroscope.

[0030] Preferably, the specific content of S2 includes:

[0031] Using the angular velocity output by the SINS gyroscope Calculate the velocity of the star's centroid coordinates on the image plane.

[0032]

[0033] In the formula, (u k ,v k ) for t kThe coordinates of the centroid of the star points in the time-lapse star chart; f is the focal length of the star sensor; c ij Install a matrix for the star sensor The element in the i-th row and j-th column, where i = 1, 2, 3, j = 1, 2, 3; This refers to the angular rate output by the SINS gyroscope.

[0034] According to t k The coordinates of the centroid of the star at time (u) k ,v k and the speed of movement of the centroid coordinates of the star point Calculate t k+1 Predicted centroid coordinates of star points at time [time]

[0035]

[0036] Predicted values ​​based on the centroid coordinates of each star point Centered on a target point, the centroid of the star is extracted within a preset local window to obtain the measured coordinates of the star's centroid.

[0037] Preferably, the specific content of S3 includes:

[0038] The centroid coordinates of the star point are measured as a quantity of the tracking channel filter. The measurement equation for the tracking channel filter is established as follows:

[0039] Z c =H c X c +V c

[0040] In the formula,

[0041]

[0042] V c =[v u v v ] T The measurement noise vector represents the coordinates of the centroid of the star point.

[0043] The measured values ​​are fed into the tracking channel filter to obtain high-precision estimates of the centroid coordinates of the star points and the corresponding mean square error matrix.

[0044] Preferably, high-precision estimates of the centroid coordinates of star points and the corresponding mean square error matrix are obtained through Kalman filtering.

[0045] Preferably, the specific content of establishing the SINS / CNS deep integrated navigation state equation in S4 includes:

[0046] The position, velocity, and attitude of the vehicle are calculated, and the state variable X of the SINS / CNS deep integrated navigation filter is selected as the mathematical platform misalignment angle in the geographic system. Speed ​​error δv n =[δv E δv N δv U ] T Position error δp=[δL δλ δh] T gyroscope constant drift ε b =[ε x ε y ε z ] T and accelerometer zero bias

[0047] The state equation for the SINS / CNS deep combined navigation filter is established as follows:

[0048]

[0049] In the formula,

[0050]

[0051]

[0052]

[0053]

[0054]

[0055]

[0056]

[0057] 0 3×3 R is a 3x3 matrix containing all zeros. M and R N λ, L, and h represent the radii of curvature of the Earth's meridian and circumference, respectively; λ, L, and h represent the longitude, latitude, and altitude of the carrier, respectively; ω ie This is the Earth's rotational angular rate; This is the component of the Earth's rotational angular rate in the geographic frame; for The antisymmetric matrix formed; For geographical comparison f n The antisymmetric matrix formed; v n =[v E v N v U ] TFor geographic download speed; A v For v n The antisymmetric matrix formed; A ω for The antisymmetric matrix formed; w g and w a These represent the measurement noise vectors of the gyroscope and accelerometer, respectively.

[0058] Preferably, the specific content of establishing the direct star measurement equations for SINS / CNS deep integrated navigation includes:

[0059] If it is a direct-fire star, then based on the attitude matrix output by the inertial navigation subsystem... Estimate the coordinates of the centroid of the directly incident star. The difference in centroid coordinates of the direct star points output by the inertial navigation subsystem and the celestial navigation subsystem is used as the measurement to establish the direct star measurement equation for SINS / CNS deep integrated navigation:

[0060] Z1 = H1X + V1

[0061] In the formula:

[0062]

[0063]

[0064]

[0065]

[0066]

[0067] Let be the starlight vector of the j-th directly incident star in the star sensor coordinate system; Let be the antisymmetric matrix of the starlight vector of the j-th direct star in the star sensor coordinate system.

[0068] Preferably, the specific content of establishing the refraction star measurement equations for SINS / CNS deep integrated navigation includes:

[0069] If it is a refracting star, the apparent altitude of the refracting star is calculated based on the star point coordinates output by the tracking channel filter. Simultaneously, the apparent altitude of the refracting star is estimated based on the position output by SINS. The difference between the apparent altitudes of the refracting star output by SINS and CNS is used as a measurement to establish the refracting star measurement equation for SINS / CNS deep integrated navigation:

[0070] Z2=H2X+V2

[0071] In the formula:

[0072]

[0073] H2 = [0 n×6 H A H B 0 n×6 V2 = -[v] h1 v h2 … v hn ] T ;

[0074]

[0075]

[0076]

[0077]

[0078] x, y, z represent the positions of the carrier in the inertial frame; [u x u y u z ] T R is the starlight vector of the j-th refracting star before refraction; j Let be the angle of refraction of the j-th refracting star.

[0079] Preferably, in S5, Kalman filtering is used to fuse information between the inertial navigation subsystem and the celestial navigation subsystem.

[0080] A SINS / CNS deep integrated navigation system, based on the inertial navigation subsystem SINS and the astronomical navigation subsystem CNS, includes: a tracking channel filter state equation establishment module, a star centroid coordinate measurement calculation module, a tracking channel filter, a direct star and refracted star discrimination module, and a fusion correction module;

[0081] The tracking channel filter state equation establishment module is used to establish the tracking channel filter state equation for each star based on the angular velocity information measured by the SINS gyroscope.

[0082] The star centroid coordinate measurement calculation module is connected to the tracking channel filter state equation establishment module, and is used to calculate t based on the tracking channel filter state equation. k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point.

[0083] The tracking channel filter is connected to the star centroid coordinate measurement calculation module to obtain the star centroid coordinate measurement value as a quantity measurement, and to estimate the star centroid coordinate estimate and the corresponding estimation mean square error matrix;

[0084] The direct star and refracted star discrimination module is connected to the tracking channel filter. It is used to distinguish between direct stars and refracted stars based on the estimated centroid coordinates of the star points output by the tracking channel filter, and to establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation and refracted star measurement equation respectively.

[0085] The fusion correction module is connected to the direct star and refracted star discrimination module. It is used to update the time of the SINS / CNS deep integrated navigation filter using the SINS / CNS deep integrated navigation state equation, update the measurement of the SINS / CNS deep integrated navigation filter using the direct star measurement equation and the refracted star measurement equation, estimate the mean square error matrix as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter, perform information fusion between the inertial navigation subsystem and the astronomical navigation subsystem, and output the corrected navigation information.

[0086] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a SINS / CNS deep integrated navigation method, which has the following beneficial effects:

[0087] (1) By introducing the star sensor angular velocity information output by the SINS gyroscope, a separate tracking channel filter is established for each star. The motion model of the star point centroid coordinates is used as the state equation, and the star point centroid extraction result is used as the measurement. The star point centroid coordinates are estimated and tracked, which can improve the star point centroid estimation accuracy, thereby providing more accurate measurement information for the combined navigation filter and improving the navigation accuracy of the system.

[0088] (2) The tracking channel filter can not only output high-precision centroid coordinates of star points to provide measurement for the integrated navigation filter, but also output the estimated mean square error matrix of the centroid coordinates of each star point. This allows the integrated navigation filter to allocate different weights according to the measurement accuracy of each star and adaptively adjust the measurement noise covariance matrix of the integrated navigation filter, thereby improving the navigation performance of the system in a strong noise environment.

[0089] (3) By following the one-step prediction step of the tracking channel filter, the star sensor can predict the imaging position of the star in the current star map; thus, the centroid of the star point is extracted in the area near each predicted star point position, avoiding threshold scanning of the entire map, improving the speed of star point centroid extraction, and reducing the probability of extracting noise spikes as false stars, thereby improving the real-time performance of the integrated navigation system. Attached Figure Description

[0090] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0091] Figure 1 A flowchart illustrating a SINS / CNS deep integrated navigation method provided by the present invention;

[0092] Figure 2 This is a schematic diagram of star centroid coordinate prediction provided in an embodiment of the present invention;

[0093] Figure 3 This is a schematic diagram of a star centroid tracking channel provided in an embodiment of the present invention;

[0094] Figure 4 This is a schematic diagram illustrating the working principle of a SINS / CNS deep integrated navigation system provided in an embodiment of the present invention. Detailed Implementation

[0095] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0096] This invention discloses a SINS / CNS deep integrated navigation method, based on the inertial navigation subsystem SINS and the astronomical navigation subsystem CNS, such as... Figure 1 As shown, it includes the following steps:

[0097] S1. Based on the angular velocity information measured by the SINS gyroscope, establish the state equation of the tracking channel filter for each star;

[0098] S2. Based on the state equation of the tracking channel filter, for t k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point.

[0099] S3. The measured value of the centroid coordinates of the star point is used as a quantity. The quantity is sent to the tracking channel filter to estimate the estimated value of the centroid coordinates of the star point and the corresponding estimated mean square error matrix.

[0100] S4. Based on the estimated centroid coordinates of the star points output by the tracking channel filter, distinguish between direct stars and refracted stars, and establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation, and refracted star measurement equation respectively.

[0101] S5. The SINS / CNS deep integrated navigation state equation is used to update the time of the SINS / CNS deep integrated navigation filter. The direct star measurement equation and the refracted star measurement equation are used to update the measurement of the SINS / CNS deep integrated navigation filter. The mean square error matrix is ​​estimated as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter. The information of the inertial navigation subsystem and the astronomical navigation subsystem is fused, and the corrected navigation information is output.

[0102] To further implement the above technical solution, the specific content of S1 includes:

[0103] Using the star's center-of-mass coordinates u, v and the gyroscope's constant drift ε x ,ε y ,ε z To track the state variable X of the channel filter c The state equation for the tracking channel filter is established as follows:

[0104]

[0105] In the formula:

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] X c =[uv ε x ε y ε z ] T

[0112]

[0113]

[0114]

[0115] Where f is the focal length of the star sensor; The mounting matrix for the star sensor; The angular rate output by the SINS gyroscope; w gx ,w gy ,w gz This refers to the random measurement error of the SINS gyroscope.

[0116] To further implement the above technical solution, the specific content of S2 includes:

[0117] Using the angular velocity output by the SINS gyroscope Calculate the velocity of the star's centroid coordinates on the image plane.

[0118]

[0119] In the formula, (u k ,v k ) for t k The coordinates of the centroid of the star points in the time-lapse star chart; f is the focal length of the star sensor; c ij Install a matrix for the star sensor The element in the i-th row and j-th column, where i = 1, 2, 3, j = 1, 2, 3; This refers to the angular rate output by the SINS gyroscope.

[0120] According to t k The coordinates of the centroid of the star at time (u) k ,v k and the speed of movement of the centroid coordinates of the star point Calculate t k+1 Predicted centroid coordinates of star points at time [time]

[0121]

[0122] like Figure 2 As shown, after the star sensor obtains the actual star image, it predicts the value using the centroid coordinates of each star point. Centered on a target point, the centroid of the star is extracted within a preset local window to obtain the measured coordinates of the star's centroid.

[0123] To further implement the above technical solution, the specific content of S3 includes:

[0124] The centroid coordinates of the star point are measured as a quantity of the tracking channel filter. The measurement equation for the tracking channel filter is established as follows:

[0125] Z c =H c X c +V c

[0126] In the formula,

[0127]

[0128] V c =[v u v v ] T The measurement noise vector represents the coordinates of the centroid of the star point.

[0129] The measured values ​​are fed into the tracking channel filter to obtain high-precision estimates of the centroid coordinates of the star points and the corresponding mean square error matrix.

[0130] To further implement the above technical solutions, such as Figure 3 As shown, high-precision estimates of the centroid coordinates of star points and the corresponding mean square error matrix are obtained through Kalman filtering.

[0131] To further implement the above technical solutions, the specific content of establishing the SINS / CNS deep integrated navigation state equation in S4 includes:

[0132] The position, velocity, and attitude of the vehicle are calculated, and the state variable X of the SINS / CNS deep integrated navigation filter is selected as the mathematical platform misalignment angle in the geographic system. Speed ​​error δv n =[δv E δv N δv U ] T Position error δp=[δLδλδh] T gyroscope constant drift ε b =[ε x ε y ε z ] T and accelerometer zero bias

[0133] The state equation for the SINS / CNS deep combined navigation filter is established as follows:

[0134]

[0135] In the formula,

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143] 0 3×3 R is a 3x3 matrix containing all zeros. M and R N λ, L, and h represent the radii of curvature of the Earth's meridian and circumference, respectively; λ, L, and h represent the longitude, latitude, and altitude of the carrier, respectively; ω ie This is the Earth's rotational angular rate; This is the component of the Earth's rotational angular rate in the geographic frame; for The antisymmetric matrix formed; For geographical comparison f n The antisymmetric matrix formed; v n =[v E v N v U ] T For geographic download speed; A v For v n The antisymmetric matrix formed; A ω for The antisymmetric matrix formed; w g and w a These represent the measurement noise vectors of the gyroscope and accelerometer, respectively.

[0144] In this embodiment, the SINS navigation calculation unit uses IMU measurement information to calculate the position, velocity, and attitude of the carrier.

[0145] To further implement the above technical solution, the specific content of establishing the direct star measurement equation for SINS / CNS deep integrated navigation includes:

[0146] If it is a direct-fire star, then based on the attitude matrix output by the inertial navigation subsystem... Estimate the coordinates of the centroid of the directly incident star. The difference in centroid coordinates of the direct star points output by the inertial navigation subsystem and the celestial navigation subsystem is used as the measurement to establish the direct star measurement equation for SINS / CNS deep integrated navigation:

[0147] Z1 = H1X + V1

[0148] In the formula:

[0149]

[0150]

[0151]

[0152]

[0153]

[0154] Let be the starlight vector of the j-th directly incident star in the star sensor coordinate system; Let be the antisymmetric matrix of the starlight vector of the j-th direct star in the star sensor coordinate system.

[0155] To further implement the above technical solutions, the specific content of establishing the refraction star measurement equations for SINS / CNS deep integrated navigation includes:

[0156] If it is a refracting star, the apparent altitude of the refracting star is calculated based on the star point coordinates output by the tracking channel filter. Simultaneously, the apparent altitude of the refracting star is estimated based on the position output by SINS. The difference between the apparent altitudes of the refracting star output by SINS and CNS is used as a measurement to establish the refracting star measurement equation for SINS / CNS deep integrated navigation:

[0157] Z2=H2X+V2

[0158] In the formula:

[0159]

[0160] H2 = [0 n×6 H A H B 0 n×6 V2 = -[v] h1 v h2 … v hn ] T ;

[0161]

[0162]

[0163]

[0164]

[0165] x, y, z represent the positions of the carrier in the inertial frame; [u x u y u z ] T R is the starlight vector of the j-th refracting star before refraction; j Let be the angle of refraction of the j-th refracting star.

[0166] To further implement the above technical solution, Kalman filtering is used in S5 to fuse information between the inertial navigation subsystem and the celestial navigation subsystem.

[0167] A SINS / CNS deep integrated navigation system, based on the inertial navigation subsystem SINS and the astronomical navigation subsystem CNS, includes: a tracking channel filter state equation establishment module, a star centroid coordinate measurement calculation module, a tracking channel filter, a direct star and refracted star discrimination module, and a fusion correction module;

[0168] The tracking channel filter state equation establishment module is used to establish the tracking channel filter state equation for each star based on the angular velocity information measured by the SINS gyroscope.

[0169] The star centroid coordinate measurement calculation module is connected to the tracking channel filter state equation establishment module, and is used to calculate t based on the tracking channel filter state equation. k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point.

[0170] The tracking channel filter is connected to the star centroid coordinate measurement calculation module to obtain the star centroid coordinate measurement value as a quantity measurement, and to estimate the star centroid coordinate estimate and the corresponding estimation mean square error matrix;

[0171] The direct star and refracted star discrimination module is connected to the tracking channel filter. It is used to distinguish between direct stars and refracted stars based on the estimated centroid coordinates of the star points output by the tracking channel filter, and to establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation and refracted star measurement equation respectively.

[0172] The fusion correction module is connected to the direct star and refracted star discrimination module. It is used to update the time of the SINS / CNS deep integrated navigation filter using the SINS / CNS deep integrated navigation state equation, update the measurement of the SINS / CNS deep integrated navigation filter using the direct star measurement equation and the refracted star measurement equation, estimate the mean square error matrix as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter, perform information fusion between the inertial navigation subsystem and the astronomical navigation subsystem, and output the corrected navigation information.

[0173] In this embodiment, the working principle of a SINS / CNS deep integrated navigation system is as follows: Figure 4 As shown.

[0174] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0175] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A SINS / CNS deep integrated navigation method, based on the inertial navigation subsystem (SINS) and the celestial navigation subsystem (CNS), characterized in that, Includes the following steps: S1. Based on the angular velocity information measured by the SINS gyroscope, establish the state equation of the tracking channel filter for each star; S2. Based on the state equation of the tracking channel filter, for t k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point. S3. The measured value of the centroid coordinates of the star point is used as a quantity. The quantity is sent to the tracking channel filter to estimate the estimated value of the centroid coordinates of the star point and the corresponding estimated mean square error matrix. S4. Based on the estimated centroid coordinates of the star points output by the tracking channel filter, distinguish between direct stars and refracted stars, and establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation, and refracted star measurement equation respectively. S5. The SINS / CNS deep integrated navigation state equation is used to update the time of the SINS / CNS deep integrated navigation filter. The direct star measurement equation and the refracted star measurement equation are used to update the measurement of the SINS / CNS deep integrated navigation filter. The mean square error matrix is ​​estimated as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter. The information of the inertial navigation subsystem and the astronomical navigation subsystem is fused, and the corrected navigation information is output.

2. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of S1 includes: Using the star's center-of-mass coordinates u, v and the gyroscope's constant drift ε x ,ε y ,ε z To track the state variable X of the channel filter c The state equation for the tracking channel filter is established as follows: In the formula: X c =[uv e x e y e z ] T Where f is the focal length of the star sensor; The mounting matrix for the star sensor; The angular rate output by the SINS gyroscope; w gx ,w gy ,w gz This refers to the random measurement error of the SINS gyroscope.

3. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of S2 includes: Using the angular velocity output by the SINS gyroscope Calculate the velocity of the star's centroid coordinates on the image plane. In the formula, (u k ,v k ) for t k The coordinates of the centroid of the star points in the time-lapse star chart; f is the focal length of the star sensor; c ij Install a matrix for the star sensor The element in the i-th row and j-th column, where i = 1, 2, 3, j = 1, 2, 3; This refers to the angular rate output by the SINS gyroscope. According to t k The coordinates of the centroid of the star at time (u) k ,v k and the speed of movement of the centroid coordinates of the star point Calculate t k+1 Predicted centroid coordinates of star points at time [time] Predicted values ​​based on the centroid coordinates of each star point Centered on a target point, the centroid of the star is extracted within a preset local window to obtain the measured coordinates of the star's centroid.

4. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of S3 includes: The centroid coordinates of the star point are measured as a quantity of the tracking channel filter. The measurement equation for the tracking channel filter is established as follows: Z c =H c X c +V c In the formula, V c =[v u v v ] T The measurement noise vector represents the coordinates of the centroid of the star point. The measured values ​​are fed into the tracking channel filter to obtain high-precision estimates of the centroid coordinates of the star points and the corresponding mean square error matrix.

5. The SINS / CNS deep integrated navigation method according to claim 4, characterized in that, High-precision estimates of the centroid coordinates of the star points and the corresponding mean square error matrix are obtained through Kalman filtering.

6. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of establishing the SINS / CNS deep integrated navigation state equation in S4 includes: The position, velocity, and attitude of the vehicle are calculated, and the state variable X of the SINS / CNS deep integrated navigation filter is selected as the mathematical platform misalignment angle in the geographic system. Speed ​​error δv n =[δv E δv N δv U ] T Position error δp=[δL δλ δh] T gyroscope constant drift ε b =[ε x ε y ε z ] T and accelerometer zero bias The state equation for the SINS / CNS deep combined navigation filter is established as follows: In the formula, 0 3×3 R is a 3x3 matrix containing all zeros. M and R N λ, L, and h represent the radii of curvature of the Earth's meridian and circumference, respectively; λ, L, and h represent the longitude, latitude, and altitude of the carrier, respectively; ω ie This is the Earth's rotational angular rate; This is the component of the Earth's rotational angular rate in the geographic frame; for The antisymmetric matrix formed; For geographical comparison f n The antisymmetric matrix formed; v n =[v E v N v U ] T For geographic download speed; A v For v n The antisymmetric matrix formed; A ω for The antisymmetric matrix formed; w g and w a These represent the measurement noise vectors of the gyroscope and accelerometer, respectively.

7. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of establishing the direct star measurement equations for SINS / CNS deep integrated navigation includes: If it is a direct-fire star, then based on the attitude matrix output by the inertial navigation subsystem... Estimate the coordinates of the centroid of the directly incident star. The difference in centroid coordinates of the direct star points output by the inertial navigation subsystem and the celestial navigation subsystem is used as the measurement to establish the direct star measurement equation for SINS / CNS deep integrated navigation: Z1 = H1X + V1 In the formula: Let be the starlight vector of the j-th directly incident star in the star sensor coordinate system; Let be the antisymmetric matrix of the starlight vector of the j-th direct star in the star sensor coordinate system.

8. The SINS / CNS deep integrated navigation method according to claim 1, characterized in that, The specific content of establishing the refraction star measurement equations for SINS / CNS deep integrated navigation includes: If it is a refracting star, the apparent altitude of the refracting star is calculated based on the star point coordinates output by the tracking channel filter. Simultaneously, the apparent altitude of the refracting star is estimated based on the position output by SINS. The difference between the apparent altitudes of the refracting star output by SINS and CNS is used as a measurement to establish the refracting star measurement equation for SINS / CNS deep integrated navigation: Z2=H2X+V2 In the formula: H2=[0 n×6 H A H B 0 n×6 ];V2=-[v h1 v h2 …v hn ] T ; x, y, z represent the positions of the carrier in the inertial frame; [u x u y u z ] T R is the starlight vector of the j-th refracting star before refraction; j Let be the angle of refraction of the j-th refracting star.

9. A SINS / CNS deep integrated navigation method according to claim 1, characterized in that, In S5, Kalman filtering is used to fuse information between the inertial navigation subsystem and the celestial navigation subsystem.

10. A SINS / CNS deep integrated navigation system, based on an inertial navigation subsystem (SINS) and an astronomical navigation subsystem (CNS), characterized in that, include: The system includes a tracking channel filter state equation establishment module, a star centroid coordinate measurement calculation module, a tracking channel filter, a direct star / refracting star discrimination module, and a fusion correction module. The tracking channel filter state equation establishment module is used to establish the tracking channel filter state equation for each star based on the angular velocity information measured by the SINS gyroscope. The star centroid coordinate measurement calculation module is connected to the tracking channel filter state equation establishment module, and is used to calculate t based on the tracking channel filter state equation. k The coordinates of the centroid of the star at time t are used to predict t in one step. k+1 The predicted value of the centroid coordinates of the star point at time 1, and the centroid of the star point is extracted within a preset local window centered on the predicted value of the centroid coordinates of the star point to obtain the measured value of the centroid coordinates of the star point. The tracking channel filter is connected to the star centroid coordinate measurement calculation module to obtain the star centroid coordinate measurement value as a quantity measurement, and to estimate the star centroid coordinate estimate and the corresponding estimation mean square error matrix; The direct star and refracted star discrimination module is connected to the tracking channel filter. It is used to distinguish between direct stars and refracted stars based on the estimated centroid coordinates of the star points output by the tracking channel filter, and to establish the SINS / CNS deep integrated navigation state equation, direct star measurement equation and refracted star measurement equation respectively. The fusion correction module is connected to the direct star and refracted star discrimination module. It is used to update the time of the SINS / CNS deep integrated navigation filter using the SINS / CNS deep integrated navigation state equation, update the measurement of the SINS / CNS deep integrated navigation filter using the direct star measurement equation and the refracted star measurement equation, estimate the mean square error matrix as the measurement noise covariance matrix of the SINS / CNS deep integrated navigation filter, perform information fusion between the inertial navigation subsystem and the astronomical navigation subsystem, and output the corrected navigation information.

Images