Inertial navigation aided navigation positioning method and system

Abstract

The invention provides an inertial navigation aided navigation positioning method and system, and the method comprises the steps: calculating the coordinate of each navigation satellite in an ECEF coordinate system according to the satellite ephemeris of a satellite navigation system; according to the navigation satellite coordinate and the inertial navigation system positioning result, the azimuth angle and the pitch angle of the navigation satellite relative to the optical detection equipment under the ENU coordinate system are solved, and the navigation satellite is tracked; acquiring star maps collected by the optical detection equipment, matching the star maps through a star map recognition algorithm, resolving a coordinate transformation matrix between two continuous frames of star maps, and recognizing fixed stars and satellites in the star maps based on the transformation matrix; converting the identified fixed star in the field of view into an ECEF coordinate system, calculating an observation angular distance between the fixed star and the satellite, and calculating a satellite observation vector in the ECEF coordinate system according to the observation angular distance; and performing error correction on the positioning result of the inertial navigation system based on the satellite observation vector. Through the scheme, the positioning precision of the inertial navigation system can be improved, and the influence of interference deception signals is reduced.

Description

Technical Field

[0001] This invention belongs to the field of astronomical navigation technology, and in particular relates to an inertial navigation-assisted navigation and positioning method and system. Background Technology

[0002] Inertial navigation systems (INS), as autonomous navigation systems that do not rely on external information, offer high navigation and positioning accuracy. However, they typically suffer from accumulated time errors. For long-term navigation needs, they generally require integration with other navigation systems to correct these accumulated errors. Using satellites for positioning and navigation to correct INS errors is currently the primary method. However, as a passive, non-autonomous navigation method, satellite navigation receivers are susceptible to interference and deception of the signals transmitted by navigation satellites, thus affecting navigation and positioning accuracy. Summary of the Invention

[0003] In view of this, embodiments of the present invention provide an inertial navigation-assisted navigation and positioning method and system to solve the problem that the signals transmitted by current navigation satellites may be interfered with and deceived, affecting the accuracy of navigation and positioning.

[0004] In a first aspect of the present invention, an inertial navigation-assisted navigation and positioning method is provided, comprising: Calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system; Based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated, and the optical detection device is controlled to track the navigation satellite with an elevation angle greater than the preset value. The system acquires star images collected by optical detection equipment, matches stars in the star images using a star image recognition algorithm, calculates the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star images, and identifies stars and satellites in the star images based on the transformation matrix. Based on star database data, all identified stars in the field of view are transformed from the celestial coordinate system to the ECEF coordinate system, and the observation angular distance between each star and the satellite is calculated. Based on the observation angular distance, the satellite observation vector of the same satellite at different times in the ECEF coordinate system is calculated. Error correction is performed on the positioning results of the inertial navigation system based on the satellite observation vectors to obtain real-time inertial navigation positioning.

[0005] In a second aspect of the present invention, a system for inertial navigation-assisted navigation and positioning is provided, comprising: The position prediction module is used to calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system. The satellite tracking module is used to calculate the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, and to control the optical detection device to track navigation satellites with elevation angles greater than preset values. The star map recognition module is used to acquire star maps collected by optical detection equipment, match stars in the star map using a star map recognition algorithm, calculate the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star maps, and identify stars and satellites in the star map based on the transformation matrix. The satellite calculation module is used to transform all identified stars in the field of view from the celestial coordinate system to the ECEF coordinate system based on star database data, and calculate the observation angular distance between each star and the satellite. Based on the observation angular distance, it calculates the satellite observation vector of the same satellite in the ECEF coordinate system at different times. The positioning calibration module is used to correct the positioning results of the inertial navigation system based on the satellite observation vectors, so as to obtain the real-time positioning of the inertial navigation system.

[0006] In a third aspect of the present invention, an electronic device is provided, including a memory, a processor, and a computer program stored in the memory and executable by the processor, wherein the processor executes the computer program to implement the steps of the method as described in the first aspect of the present invention.

[0007] In a fourth aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the method provided in the first aspect of the present invention.

[0008] In this embodiment of the invention, navigation satellites are tracked using optical detection equipment, stars are detected using star map recognition algorithms, and star and satellite identification is achieved by combining a transformation matrix. Satellites are detected based on the invariance of angular distance between stars, and the angular distance between stars and satellites is used as a measurement value. The observation vectors of the same satellite at different times are fused to correct the accumulated error of the inertial navigation system, thereby effectively improving the positioning accuracy of the inertial navigation equipment. The implementation cost is low and the positioning accuracy is high. It can achieve autonomous positioning and navigation in the presence of interference from satellite navigation signals, and has good autonomy and stealth. Attached Figure Description

[0009] To more clearly illustrate the technical solutions in the embodiments of the present invention, 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0010] Figure 1 Schematic diagrams of various coordinate systems provided for one embodiment of the present invention; Figure 2 This is a flowchart illustrating an inertial navigation-assisted navigation and positioning method according to an embodiment of the present invention. Figure 3 A schematic diagram of positioning calculation based on the angular distance between stars and satellites provided in one embodiment of the present invention; Figure 4 This is a schematic diagram of the structure of a system for inertial navigation-assisted navigation and positioning according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of an electronic device provided in one embodiment of the present invention. Detailed Implementation

[0011] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0012] It should be understood that the terms "comprising" and other similar expressions in the specification, claims, and accompanying drawings of this invention are intended to cover a non-exclusive inclusion, such as a process, method, system, or apparatus that includes a series of steps or units and is not limited to the listed steps or units. Furthermore, "first" and "second" are used to distinguish different objects and are not intended to describe a specific order.

[0013] It is understood that the inertial navigation-assisted positioning method provided in this embodiment involves four coordinate systems, including the station-centered coordinate system (ENU), the geocentric-ground-fixed coordinate system (ECEF), the celestial inertial coordinate system, and the optical detector coordinate system, such as... Figure 1 As shown, Figure 1 (a) is a description of the station-centered coordinate system. Figure 1 (b) is a description of the geocentric Earth-fixed coordinate system. Figure 1 (c) is a description of the celestial coordinate system. Figure 1 (d) describes the coordinate system of the optical detector. The coordinate systems are defined as follows: ENU coordinate system: For a point P on the Earth's surface, the origin of the ENU coordinate system is point P. A tangent plane to the Earth's ellipsoid is drawn through point P. The Y-axis is taken as due north, the X-axis as due east, and the Z-axis points in the direction of the normal.

[0014] The geocentric-fixed coordinate system (ECEF coordinate system) has the Earth's center as the origin. The X-axis points to the intersection of the prime meridian and the equator, that is, the intersection of the 0° longitude and the 0° latitude. The Z-axis points to the Earth's North Pole, that is, the Z-axis coincides with the Earth's rotation axis. The Y-axis and X-axis together with the Z-axis form a right-handed coordinate system.

[0015] Celestial inertial coordinate system (i-coordinate system): with the Earth's center as the reference origin, the Z-axis is parallel to the Earth's rotation axis and points to the North Pole, also known as the celestial axis, the X-axis points to the vernal equinox, and the Y-axis is perpendicular to the plane formed by the X-axis and Z-axis, forming a right-handed rectangular coordinate system.

[0016] Optical detector coordinate system (S-coordinate system): The optical focus of the optical detector is taken as the principal point of the coordinate system, and the optical axis of the optical detector is taken as the Z-axis direction of the coordinate system. The XOY plane is parallel to the CMOS plane, the X-axis of the coordinate system is parallel to the X-axis direction of the CMOS, and the Y-axis and X-axis together with the Z-axis form a right-handed coordinate system.

[0017] The transformation between coordinate systems can be calculated using the following method: (1) Transformation between the geocentric coordinate system and the station-centered coordinate system Position coordinates in the Earth-centered Earth-fixed coordinate system are generally represented in two ways: latitude, longitude, and altitude. The position coordinates in the station-centered coordinate system can be represented using the rectangular coordinate system method (x, y, z), while the pointing coordinates in the station-centered coordinate system are generally represented using elevation and azimuth angles. The transformation formulas between different coordinate systems and their representation methods are as follows: ① Transformation between latitude, longitude, and altitude in the geocentric coordinate system and the rectangular coordinate system ; in, , For the Earth's semi-major axis, This refers to the Earth's eccentricity.

[0018] ② Transformation between the Earth-centered Earth-fixed coordinate system and the rectangular coordinate system to latitude, longitude, and altitude Variable initialization ; ; ; Iterative computation ; ; ; ; Continue until the iteration converges.

[0019] ③ Conversion between Earth-fixed coordinate system and station-centered coordinate system The rotation matrix between the Earth-fixed coordinate system and the station-center coordinate system is: ; ④ Conversion between rectangular coordinates and elevation / azimuth coordinates in the station coordinate system Assume the rectangular coordinate point in the station center coordinate system is Its elevation angle With azimuth It can be calculated as ; ; For ease of subsequent calculations and descriptions, the four transformations mentioned above will be represented as follows: , , , .

[0020] (2) Transformation between the celestial inertial coordinate system and the geocentric coordinate system Positions in the celestial coordinate system are generally represented by unit vectors (x, y, z) or by right ascension and declination. α , β The conversion between the two representation methods is expressed as follows: ; Neglecting the effects of precession and nutation, the transformation formula between the celestial inertial coordinate system and the Earth-fixed coordinate system is: ; in , , These represent rotation matrices representing rotations around the corresponding coordinate axes by the corresponding angles. This represents the polar motion component of the Earth's axis. It is Greenwich Mean Time.

[0021] It's also understandable that the optical system needs to point towards the current area of ​​the sky where the satellite is located to achieve stable satellite tracking. Determining the optical system's pointing direction requires knowing the current coordinates of the satellite and the optical system. However, the current position of the optical system is a variable to be determined by the system and cannot be directly obtained. But since the optical detection system is used for inertial navigation-assisted positioning, the system can obtain a rough positioning based on the accumulated error of the inertial navigation system over a certain period of time. Generally, for tracking medium-Earth orbit satellites, a 1km rough positioning error will cause a pointing angle error of no more than 10 arcseconds, which generally does not affect the area of ​​the sky that the optical system is pointing towards.

[0022] Please see Figure 2A flowchart illustrating an inertial navigation-assisted navigation and positioning method provided in this embodiment of the invention includes: S201. Calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system. Satellite ephemeris is a data system that describes the orbital information of a satellite. It determines the satellite's position, velocity, and motion status using the six orbital parameters of Kepler's laws. It can generally be obtained by broadcasting from satellite navigation systems such as GPS and BeiDou.

[0023] The ECEF coordinate system, also known as the Earth-Centered, Earth-Fixed coordinate system, is a geocentric coordinate system with the Earth's center as its origin. Figure 1 As shown in (b).

[0024] The main usable information included in the satellite's ephemeris parameters is: reference time and mean perihelion angle. Correction term for satellite mean angular velocity eccentricity of satellite elliptical orbit e The square root of the semi-major axis of the satellite's elliptical orbit The right ascension of the ascending node of the satellite orbit, Ω e The inclination of the satellite's orbital plane relative to the Earth's equatorial plane at the reference time. angular distance from perigee of satellite orbit ω The rate of change of the right ascension of the ascending node of the satellite orbit, Ω; the rate of change of the plane inclination of the satellite orbit. Harmonic correction term for ascending node distance , Harmonic correction term for satellite geocentric radius , Harmonic correction term for satellite orbital inclination , Ephemeris data reference time It also includes the satellite's clock bias parameters. , , and group delay time correction TGD .

[0025] The ephemeris data package of navigation satellites contains ephemeris data from multiple satellite navigation systems, including GPS and BeiDou. Based on satellite orbit prediction calculations, the coordinates of each navigation satellite in the ECEF coordinate system are calculated. The coordinates of the navigation satellite in the ECEF coordinate system are mainly used for real-time satellite tracking and navigation positioning calculations, and the times corresponding to the coordinate positions used in these two steps are different. The satellite position used for the real-time satellite tracking step is calculated by the turntable control module, requiring high-frequency calculations to achieve real-time tracking of the satellite by the turntable system; the satellite position used for the navigation positioning calculation step is determined by the intermediate time of image acquisition and exposure by the optical detection equipment, and is calculated independently.

[0026] Specifically, based on satellite ephemeris data, the satellite's normalized time, perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time are calculated. Based on the satellite perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time, the satellite's coordinates in the ECEF coordinate system are calculated.

[0027] The steps for calculating the position coordinates of a satellite at any given time using ephemeris data are as follows: The normalized time is calculated using ephemeris data provided by satellites relative to a reference time. To calculate the satellite position information at the observation time, it is necessary to calculate the time relative to the reference time. Furthermore, to obtain more accurate time information, corrections need to be made for the satellite clock's deviation and drift. These corrections are based on the reference time. The time, i.e., the clock error correction amount, is calculated as follows: ; ; Therefore, the satellite data transmission time is corrected to... ; Therefore, the normalization time is .

[0028] Calculate the average angular velocity of the satellite's orbit. The theoretical angular velocity of the satellite's orbit is calculated as follows: ; The navigation ephemeris includes an angular velocity perturbation correction term, and the average angular velocity after perturbation correction is: ; calculate The mean anterior angle and the deviated anterior angle at time t, and the mean anterior angle and time satisfy a linear relationship as follows: ; The following relationship exists between the angle of approach and the angle of deviance: ; The approach angle can be calculated using an iterative method. E .

[0029] Calculate the satellite's geocentric radius. ; Calculate the true anomaly angle of the satellite at the normalized time. f , ; Calculate the angular distance of the ascending node φ , ; Calculate the perturbation correction term and the ascending node angular distance correction term. ; Satellite geocentric radial correction term ; Satellite orbital inclination correction term ; Corrected ascending node distance φ Satellite geocentric radius r and satellite orbital inclination i for ; ; .

[0030] Calculate the coordinates of the satellite orbit in a rectangular coordinate system. .

[0031] Calculate the right ascension of the ascending node at the normalized time. ; in This is the Earth's rotational angular rate. .

[0032] Calculate the coordinates of the satellite in the ECEF coordinate system: .

[0033] S202. Based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, calculate the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system, and control the optical detection device to track the navigation satellite with an elevation angle greater than the preset value. Optionally, the zero position of the optical detection equipment turntable is aligned with the ENU coordinate system, the zero position of the turntable pitch angle points to the local horizontal tangent direction, the zero position of the turntable azimuth angle points to the local due north direction, and the turntable is controlled to point to the predetermined sky area, that is, the sky area where the navigation satellite is located.

[0034] The turntable's pitch zero-position alignment is achieved by measuring the platform's levelness using an electronic level and adjusting the platform's levelness to ensure zero-position alignment. The turntable's azimuth zero-position alignment is achieved using known landmarks. Simultaneously, the turntable control system predicts satellite positions at a 10Hz frequency while receiving uncorrected positioning results from the inertial navigation system.

[0035] Calculate the azimuth and elevation angles of all navigation satellites relative to the optical detection equipment in the ENU coordinate system, track satellites with elevation angles greater than a preset value (e.g., 30 degrees), and control the turntable to point to the designated sky area based on the calculated azimuth and elevation angles to complete the real-time tracking of the satellites to be observed.

[0036] The process involves obtaining the uncorrected positioning results of the inertial navigation system (INS) and calculating the INS coordinates in the ECEF coordinate system. Based on the coordinates of the navigation satellite and the INS in the ECEF coordinate system, the pointing vector of the optical detection device relative to the satellite in the ECEF coordinate system is calculated. Based on the pointing vector, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated through coordinate system transformation.

[0037] As an inertial navigation aid, the optical detection system can obtain a rough positioning result from the inertial navigation system, which has a certain amount of accumulated error over time. Assume the inertial navigation system's solution is... Given the current approximate location's longitude, latitude, and altitude, the inertial navigation system's solution in the ECEF coordinate system is as follows: ; Calculate the satellite's specific position coordinates in the ECEF coordinate system. Coordinates of the user's current position in the ECEF coordinate system Then the pointing vector of the optical system to the satellite in the ECEF coordinate system can be directly calculated, that is... ; The elevation and azimuth angles of the optical system relative to the satellite are then: .

[0038] S203. Acquire star images collected by optical detection equipment, match stars in the star images using star image recognition algorithms, calculate the transformation matrix between the coordinate systems of the optical detector corresponding to two consecutive star images, and identify stars and satellites in the star images based on the transformation matrix. Optical detection equipment is an instrument that uses radiation to alter the conductivity of irradiated materials, and it can collect star maps. A star map is an image that records the distribution of celestial objects and is acquired by optical detection equipment. Star map recognition algorithms identify stars and other celestial objects by extracting characteristic parameters such as the position and brightness of stars, comparing the observed star map with reference stars in a navigation star database, and using methods such as feature similarity or geometric relationships.

[0039] The optical detection equipment acquires images of the pointed sky region at a certain frequency and records the exposure time of the acquired images. The acquired star map images contain satellites, stars, and some visible noise. After certain preprocessing and segmentation of the images, the centroids of the target stars in the images are located. Star recognition algorithms are used to match the stars, and the same stars in two consecutive frames are matched. The transformation matrix between the coordinate systems of the optical detector corresponding to the two consecutive frames is calculated.

[0040] In this embodiment, stars can be identified using a star map recognition algorithm. Due to the limitations of the star database and the detection capabilities of the optical system, it is difficult to detect all the images of stars using the star map recognition algorithm. Furthermore, due to the presence of background noise, the extracted star points include real star targets, satellite targets, and noise points. Therefore, after identification using the star map recognition algorithm, in addition to the identified stars, the unidentified stars, satellites, and noise points can all be identified as false stars.

[0041] Specifically, the identified stars in the star map are extracted by the star map recognition algorithm. Based on the star vectors of the identified stars in the coordinate system of the optical detection device in two consecutive frames of star map, the star point coordinate transformation matrix is ​​calculated by the least squares method. Based on the transformation matrix, the star points in the star map are determined to be stars and satellites by comparing the off-target amount and position of the star point coordinates in two consecutive frames of star map acquired in real time.

[0042] In this method, star points whose observed coordinates coincide with the predicted coordinates in the next frame are considered stars, while star points whose coordinates do not coincide are considered satellites.

[0043] Assume the first k The number of stars identified in the frame star map is , No. k The number of stars identified by +1 frame star map is Given the known star IDs, vectors, and other information of identified stars in the star database, iterate through the identified stars in two consecutive frames. If the number of common identified stars in the two consecutive frames is... Its first position in the optical detector coordinate system k Frame and the k The star vectors of +1 frame are respectively , The method for calculating the star vector in the optical detector coordinate system is as follows: ; For the first k The first in the frame star map i The imaging coordinates of a star on the CMOS plane. If the first... k The optical detector coordinate system at frame time and the firstk The transformation matrix between the optical detector coordinate systems at time +1 is: Without considering the centroid positioning error, for any publicly identified star, the following condition is met: ; Combining these into a matrix representation, we have: ; For ease of representation, let , , The least squares method is generally used to solve this problem. ; No. k All extracted star points of the frame The corresponding star vector in the optical detector coordinate system is transformed by the matrix. All can be converted to the first k The coordinates of the optical detector corresponding to +1 frame, and the coordinates of the transformed star vector are: Since the vector directions between stars can be considered constant, while the angle between the vector directions between a satellite and a star is constantly changing, the vector directions of noise points in the optical detector coordinate system are random. Therefore, comparing from the first... k Frame conversion to the k +1 frame's coordinates and the first frame's miss distance k The position of the off-target coordinates extracted from +1 frame can be used to identify and detect stars and satellites, that is, let ; like If, then the star point is a stellar point; if If the star point is positive, then it is a satellite point; otherwise, it is a noise point. Related to centroid positioning error, It is related to the apparent motion angle of the satellite between consecutive frames.

[0044] The point targets corresponding to the first frame in two consecutive frames are transformed to the image plane of the second frame. The distance between the calculated position of the transformed point targets and the measured position in the second frame is compared, and stars, satellites and noise are distinguished based on the distance.

[0045] S204. Based on the star database data, all identified stars in the field of view are transformed from the celestial coordinate system to the ECEF coordinate system, and the observation angular distance between each star and the satellite is calculated. Based on the observation angular distance, the satellite observation vector of the same satellite at different times in the ECEF coordinate system is calculated. Based on stellar database data, the right ascension and declination coordinates of stars in the celestial coordinate system are known. This allows for the transformation of all stars in the field of view from the celestial coordinate system to the ECEF coordinate system. Simultaneously, the angular distances between all stars and the satellite in the field of view are calculated, along with the satellite's unit observation vector in the ECEF coordinate system. An optical detector can acquire satellite images at a certain frequency. Based on the observation angular distances between stars and the satellite, the satellite observation vectors of the same satellite at different times can be obtained. For example,... Figure 3 As shown, O-XYZ is the ECEF coordinate system, and the satellite observation vector is... ρL, The stellar observation vectors are s1, s2, and s3, respectively.

[0046] Specifically, the observation angular distance between the star and the satellite is calculated based on the unit observation vector of the star in the ECEF coordinate system; based on the observation angular distance group formed by all stars and the predetermined satellite and the right ascension and declination of the star in the star pool, the satellite observation vector in the ECEF coordinate system is solved by using the least squares method.

[0047] The number of stars in the sky far exceeds the number of medium-Earth orbit navigation satellites. When tracking satellites, there are often multiple stellar points in the field of view. The angular distance between each star and the satellite is calculated. ; in This represents the unit observation vector of the satellite in the coordinate system of the optical detector. Let be the unit observation vector of the star in the optical detector coordinate system. For an infinite point target, the angle between the unit observation vectors of the star and the satellite in the optical detector coordinate system can be considered equal to the angle between their unit observation vectors in the ECEF coordinate system. That is, the observation angular distance can be further described as... ; in This is the unit observation vector of the satellite in the ECEF coordinate system. Let be the unit observation vector of the star in the ECEF coordinate system. Each star and satellite within the field of view can form an angular distance group. Assuming there are n stars and satellites forming angular distance groups, the combination can be expressed in matrix form as follows: ; in The solution is obtained directly using the unit observation vectors of stars and satellites. Calculated using the following formula ; in Let be the right ascension and declination of the corresponding star in the star bank. For ease of expression writing, let be... , Then, the optimal solution for the satellite observation vector can be obtained using the least squares method. .

[0048] S205. Based on the satellite observation vector, the positioning results of the inertial navigation system are corrected for errors to obtain real-time inertial navigation positioning.

[0049] Real-time positioning by inertial navigation refers to the positioning result of the inertial navigation system after error correction.

[0050] Specifically, based on the satellite observation vector and the inertial navigation system positioning results, a correction factor is solved using the Newton-Raphson iteration method to minimize the inertial navigation system positioning error, and the inertial navigation system positioning results are then corrected based on the correction factor.

[0051] A single satellite observation can determine a user's location line. When the satellite is tracked and observed, multiple location lines can determine a single location point. However, the user's position may change during satellite tracking. As an inertial navigation-assisted positioning system, the inertial navigation system's output positioning result is known. Although the inertial navigation output result will accumulate errors over long-term operation, its relative positioning over a short period can be considered accurate. Assuming... m In each sampling period, the positioning result output by the inertial navigation system is: , The corresponding times are respectively If in The ECEF coordinates of the user at that time are Based on the relative positioning accuracy of inertial navigation in a short period of time, it can be approximately assumed that... The user's ECEF coordinate system position at time is ,in The satellite's ECEF coordinates are Then it exists ; in Due to the presence of errors, both sides of the equation are not strictly equal. This is especially true when performing satellite analysis. m During the subsequent tracking observations, there exists an optimal solution that minimizes the difference between both sides of the equation, i.e., minimizes the following expression: ;

[0052] In the formula, P For users coordinates of time , minimize The Newton-Raphson iteration method is generally used, let ; The gradient is defined as: ; Newton's iterative method can then be described as: ; Minimize the J(P) function and solve it iteratively. The iterative positioning result is then provided to the inertial navigation system as a correction value to correct the accumulated error of the inertial navigation system.

[0053] In this embodiment, the navigation satellite is tracked in the sky using an optical system, and stars and satellites are distinguished using a star map matching algorithm and a transformation matrix. Based on the observed angular distance between stars and satellites, the observed vectors of the same satellite at different times are fused. The accumulated error of the inertial navigation system is corrected through navigation and positioning calculations, thereby effectively improving the navigation and positioning accuracy of the inertial navigation system. The inertial navigation correction task can be completed using small optical detection equipment and a turntable system, resulting in low equipment cost and high positioning accuracy. Furthermore, by utilizing the absolute position of stars and the stable orbital characteristics of satellites, autonomous positioning and navigation are achieved through active optical detection even in the presence of interference from satellite navigation signals, providing better autonomy and stealth.

[0054] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0055] Figure 4 This invention provides a schematic diagram of a system for inertial navigation-assisted positioning, comprising: The position prediction module 410 is used to calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system. Specifically, based on satellite ephemeris data, the satellite normalized time, perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time are calculated. Based on the satellite perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time, the coordinates of the navigation satellite in the ECEF coordinate system are calculated.

[0056] The satellite tracking module 420 is used to calculate the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, and to control the optical detection device to track the navigation satellite with an elevation angle greater than a preset value. Optionally, the satellite tracking module 420 further includes: The turntable alignment unit aligns the zero position of the optical detection equipment turntable with the ENU coordinate system, with the zero position of the turntable pitch angle pointing to the local horizontal tangent direction and the zero position of the turntable azimuth angle pointing to the local due north direction, and controls the turntable to point to the predetermined sky area.

[0057] Among them, the uncorrected positioning results of the inertial navigation system are obtained, and the coordinates of the inertial navigation system in the ECEF coordinate system are calculated; Based on the coordinates of the navigation satellite and the inertial navigation system in the ECEF coordinate system, the pointing vector of the optical detection device relative to the satellite in the ECEF coordinate system is calculated. Based on the pointing vector, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated through coordinate system transformation.

[0058] The star map recognition module 430 is used to acquire star maps collected by optical detection equipment, match stars in the star map through star map recognition algorithm, calculate the transformation matrix between the coordinate systems of optical detection equipment corresponding to two consecutive frames of star map, and identify stars and satellites in the star map based on the transformation matrix. The star map recognition module 430 includes: The transformation calculation unit is used to extract the identified stars in the star map through the star map recognition algorithm, and to calculate the star coordinate transformation matrix by least squares based on the star vectors of the identified stars in the coordinate system of the optical detection device in two consecutive star maps. The star point differentiation unit is used to determine whether a star point is a star or a satellite by comparing the star point coordinate miss distance and coordinate miss distance position of two consecutive frames of star images acquired in real time, based on the transformation matrix.

[0059] In this method, star points whose observed coordinates coincide with the predicted coordinates in the next frame are considered stars, while star points whose coordinates do not coincide are considered satellites.

[0060] The satellite calculation module 440 is used to transform all identified stars in the field of view from the celestial coordinate system to the ECEF coordinate system based on the star database data, and calculate the observation angular distance between each star and the satellite. Based on the observation angular distance, it calculates the satellite observation vector of the same satellite in the ECEF coordinate system at different times. Specifically, the observation angular distance between the star and the satellite is calculated based on the unit observation vector of the star in the ECEF coordinate system; based on the observation angular distance group formed by all stars and the predetermined satellite and the right ascension and declination of the star in the star pool, the satellite observation vector in the ECEF coordinate system is solved by using the least squares method.

[0061] The positioning calibration module 450 is used to perform error correction on the positioning results of the inertial navigation system based on the satellite observation vector, so as to obtain the real-time positioning of the inertial navigation system.

[0062] Specifically, based on the satellite observation vector and the inertial navigation system positioning results, a correction factor is solved using the Newton-Raphson iteration method to minimize the inertial navigation system positioning error, and the inertial navigation system positioning results are then corrected based on the correction factor.

[0063] In some embodiments, the inertial navigation-assisted navigation and positioning system 40 is electrically connected to an optical detection device. The optical detection device is used to measure stars and navigation satellites, and has a maximum detection capability of not less than magnitude 12, so as to stably acquire stable satellite imaging information. At the same time, the inertial navigation-assisted navigation and positioning system stores a star database of a certain magnitude for star map recognition and satellite pointing calculation. It also has navigation satellite ephemeris data for predicting the position of navigation satellites.

[0064] The inertial navigation-aided navigation and positioning system is electrically connected to the turntable control module to control the turntable of the optical detection equipment to stably track navigation satellites; the inertial navigation-aided navigation and positioning system is electrically connected to an external inertial navigation system to receive uncorrected positioning data and provide corrected positioning data.

[0065] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working process of the system and modules described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0066] Figure 5 This is a schematic diagram of an electronic device according to an embodiment of the present invention. The electronic device is used for assisted positioning in an inertial navigation system. Figure 5 As shown, the electronic device 5 of this embodiment includes: a memory 510, a processor 520, and a system bus 530. The memory 510 includes an executable program 5101 stored thereon. As those skilled in the art will understand, Figure 5 The electronic device structure shown does not constitute a limitation on the electronic device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0067] The following is combined with Figure 5 A detailed introduction to each component of the electronic device: The memory 510 can be used to store software programs and modules. The processor 520 executes various functional applications and data processing of the electronic device by running the software programs and modules stored in the memory 510. The memory 510 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, application programs required for at least one function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device (such as cached data), etc. In addition, the memory 510 may include high-speed random access memory, and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0068] The memory 510 contains an executable program 5101 for a network request method. This executable program 5101 can be divided into one or more modules / units, which are stored in the memory 510 and executed by the processor 520 to achieve assisted positioning of the inertial navigation system, etc. The one or more modules / units can be a series of computer program instruction segments capable of performing specific functions, describing the execution process of the computer program 5101 in the electronic device 5. For example, the computer program 5101 can be divided into functional modules such as a position prediction module, a satellite tracking module, a star map recognition module, a satellite calculation module, and a positioning calibration module.

[0069] The processor 520 is the control center of the electronic device. It connects various parts of the electronic device via various interfaces and lines. By running or executing software programs and / or modules stored in the memory 510, and by calling data stored in the memory 510, it performs various functions and processes data, thereby monitoring the overall status of the electronic device. Optionally, the processor 520 may include one or more processing units; preferably, the processor 520 may integrate an application processor and a modem processor, wherein the application processor mainly handles the operating system, application programs, etc., and the modem processor mainly handles wireless communication. It is understood that the modem processor may also not be integrated into the processor 520.

[0070] The system bus 530 is used to connect various functional components inside the computer, transmitting data, address, and control information. Its type can be, for example, a PCI bus, an ISA bus, or a CAN bus. Instructions from the processor 520 are transmitted to the memory 510 via the bus, and the memory 510 sends data back to the processor 520. The system bus 530 is responsible for data and instruction exchange between the processor 520 and the memory 510. Of course, the system bus 530 can also connect to other devices, such as network interfaces and display devices.

[0071] In this embodiment of the invention, the executable program executed by the processor 520 included in the electronic device includes: Calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system; Based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated, and the optical detection device is controlled to track the navigation satellite with an elevation angle greater than the preset value. The system acquires star images collected by optical detection equipment, matches stars in the star images using a star image recognition algorithm, calculates the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star images, and identifies stars and satellites in the star images based on the transformation matrix. Based on star database data, all identified stars in the field of view are transformed from the celestial coordinate system to the ECEF coordinate system, and the observation angular distance between each star and the satellite is calculated. Based on the observation angular distance, the satellite observation vector of the same satellite at different times in the ECEF coordinate system is calculated. Error correction is performed on the positioning results of the inertial navigation system based on the satellite observation vectors to obtain real-time inertial navigation positioning.

[0072] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0073] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0074] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An inertial navigation-assisted navigation and positioning method, characterized in that, include: Calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system; Based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated, and the optical detection device is controlled to track the navigation satellite with an elevation angle greater than the preset value. The system acquires star images collected by optical detection equipment, matches stars in the star images using a star image recognition algorithm, calculates the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star images, and identifies stars and satellites in the star images based on the transformation matrix. Based on star database data, all identified stars in the field of view are transformed from the celestial coordinate system to the ECEF coordinate system, and the observation angular distance between each star and the satellite is calculated. Based on the observation angular distance, the satellite observation vector of the same satellite at different times in the ECEF coordinate system is calculated. Error correction is performed on the positioning results of the inertial navigation system based on the satellite observation vectors to obtain real-time inertial navigation positioning.

2. The method according to claim 1, characterized in that, The calculation of the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system includes: Based on satellite ephemeris data, the satellite normalized time, perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time are calculated. Based on the satellite perturbation correction term, satellite orbital coordinates, and right ascension of the ascending node at normalized time, the coordinates of the navigation satellite in the ECEF coordinate system are calculated.

3. The method according to claim 1, characterized in that, Before calculating the azimuth and elevation angles of the navigation satellite relative to the optical detection equipment in the ENU coordinate system based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, the following steps are included: Align the zero point of the optical detection equipment turntable with the ENU coordinate system, point the zero point of the turntable pitch angle to the local horizontal tangent direction, point the zero point of the turntable azimuth angle to the local due north direction, and control the turntable to point to the predetermined sky area.

4. The method according to claim 1, characterized in that, The calculation of the azimuth and elevation angles of the navigation satellite relative to the optical detection equipment in the ENU coordinate system, based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, includes: Obtain the uncorrected positioning results of the inertial navigation system and calculate the coordinates of the inertial navigation system in the ECEF coordinate system; Based on the coordinates of the navigation satellite and the inertial navigation system in the ECEF coordinate system, the pointing vector of the optical detection device relative to the satellite in the ECEF coordinate system is calculated. Based on the pointing vector, the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system are calculated through coordinate system transformation.

5. The method according to claim 1, characterized in that, The process of matching stars in a star map using a star map recognition algorithm, calculating the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star map frames, and identifying stars and satellites in the star map based on the transformation matrix includes: Stars identified in the star map are extracted using a star map recognition algorithm. Based on the star vectors of the identified stars in the coordinate system of the optical detection device in two consecutive star maps, the star coordinate transformation matrix is ​​calculated using the least squares method. Based on the transformation matrix, the stars and satellites in the star map are determined by comparing the off-target distances and positions of star point coordinates in two consecutive real-time acquired star maps. In this method, star points whose observed coordinates coincide with the predicted coordinates in the next frame are considered stars, while star points whose coordinates do not coincide are considered satellites.

6. The method according to claim 1, characterized in that, The calculation of the observation angular distance between each star and the satellite, and the determination of the satellite observation vector in the ECEF coordinate system at different times based on the observation angular distance, include: Calculate the observation angular distance between the star and the satellite based on the unit observation vector of the star in the ECEF coordinate system; Based on the observation angular distance group formed by all stars and the predetermined satellite, as well as the right ascension and declination of the stars in the star pool, the satellite observation vector in the ECEF coordinate system is solved by using the least squares method.

7. The method according to claim 1, characterized in that, The error correction of the inertial navigation system positioning results based on the satellite observation vectors includes: Based on the satellite observation vector and the inertial navigation system positioning results, a correction factor is solved using the Newton-Raphson iteration method to minimize the inertial navigation system positioning error. The inertial navigation system positioning results are then corrected based on this correction factor.

8. A system for inertial navigation-assisted navigation and positioning, characterized in that, include: The position prediction module is used to calculate the coordinates of each navigation satellite in the ECEF coordinate system based on the satellite ephemeris broadcast by the satellite navigation system. The satellite tracking module is used to calculate the azimuth and elevation angles of the navigation satellite relative to the optical detection device in the ENU coordinate system based on the coordinates of the navigation satellite in the ECEF coordinate system and the uncorrected positioning results of the inertial navigation system, and to control the optical detection device to track navigation satellites with elevation angles greater than preset values. The star map recognition module is used to acquire star maps collected by optical detection equipment, match stars in the star map using a star map recognition algorithm, calculate the transformation matrix between the coordinate systems of the optical detection equipment corresponding to two consecutive star maps, and identify stars and satellites in the star map based on the transformation matrix. The satellite calculation module is used to transform all identified stars in the field of view from the celestial coordinate system to the ECEF coordinate system based on star database data, and calculate the observation angular distance between each star and the satellite. Based on the observation angular distance, it calculates the satellite observation vector of the same satellite in the ECEF coordinate system at different times. The positioning calibration module is used to correct the positioning results of the inertial navigation system based on the satellite observation vectors, so as to obtain the real-time positioning of the inertial navigation system.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of an inertial navigation-assisted navigation and positioning method as described in any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed, it implements the steps of an inertial navigation-assisted navigation and positioning method as described in any one of claims 1 to 7.

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