Single-antenna satellite positioning instrument aided inertial navigation rapid self-orientation method in marine environment

Abstract

The application discloses a kind of marine environment under single antenna satellite positioning instrument auxiliary inertial navigation quick self-aiding north-seeking method, comprising: when carrying out automatic north-seeking, first enter satellite positioning instrument hot start stage, wait satellite positioning instrument completes hot start;In the stage of determining the carrier heading using satellite positioning instrument position information, first the position accuracy attenuation factor of satellite positioning instrument is judged, based on the determination result determines the time for collecting the position information provided by satellite positioning instrument, and the collected position information is converted, obtains the three-dimensional coordinates of carrier under the earth-centered coordinate system, and determines the carrier heading angle based on the three-dimensional coordinates;In the fine alignment stage, inertial navigation system is based on the carrier heading angle, combined with filter algorithm, fine alignment for a predetermined period of time is carried out, to realize automatic north-seeking process.The application solves the problems of long alignment time, great influence of carrier motion and other problems of traditional self-aiding north-seeking method in complex dynamic environment of ocean, improves navigation accuracy and reliability.

Description

Technical Field

[0001] This invention relates to the field of marine navigation technology, specifically to a method for rapid self-north finding using a single-antenna satellite positioning system-assisted inertial navigation in a marine environment. Background Technology

[0002] In the marine environment, the in-flight north-finding process of an inertial navigation system (INS) is crucial for the navigation of ships and other vessels. Traditional in-flight north-finding methods typically employ a "coarse alignment + fine alignment" scheme. Coarse alignment requires 3 minutes to roughly estimate the approximate heading and horizontal attitude of the vessel, while the initial attitude for fine alignment depends on the attitude value estimated at the end of coarse alignment. The entire alignment process is time-consuming (generally 5-10 minutes). However, in the marine environment, ships undergo complex dynamic motions, including various six-degree-of-freedom motions such as pitch, roll, and heave. This can lead to deviations in the attitude angles estimated by the coarse alignment. If the heading error angle estimated by coarse alignment is large (above 5°), it will affect the estimation effect of fine alignment, thereby reducing the initial alignment accuracy. Therefore, how to quickly and accurately complete the inertial navigation system's north-finding in the marine environment is a pressing technical problem that needs to be solved. Summary of the Invention

[0003] The purpose of this invention is to provide a method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment. This method aims to solve the problems of long alignment time and significant influence from carrier motion in traditional self-north finding methods in complex and dynamic marine environments, thereby improving navigation accuracy and reliability.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for rapid self-north finding using a single-antenna satellite positioning system-assisted inertial navigation in a marine environment, including:

[0006] Establish a process for a carrier to seek north while in motion in a marine environment, including a satellite positioning system warm-up phase, a phase of determining the carrier's course using satellite positioning system position information, and a fine alignment phase, wherein:

[0007] When performing automatic north-finding, the satellite positioning device first enters the hot start phase, waiting for the satellite positioning device to complete the hot start.

[0008] In the stage of determining the vehicle's heading using the satellite positioning system's position information, the position accuracy attenuation factor of the satellite positioning system is first judged. Based on the judgment result, the timing for collecting the position information provided by the satellite positioning system is determined. The collected position information is then transformed into coordinates to obtain the three-dimensional coordinates of the vehicle in the geocentric coordinate system. Based on these three-dimensional coordinates, the heading angle of the vehicle is determined.

[0009] During the fine alignment phase, the inertial navigation system performs fine alignment for a preset time period based on the carrier's heading angle and a filtering algorithm, thereby achieving automatic north-finding.

[0010] Furthermore, the position accuracy attenuation factor of the satellite positioning instrument is determined, and based on the determination result, the timing for collecting the position information provided by the satellite positioning instrument is determined, including:

[0011] The position accuracy attenuation factor of the satellite positioning instrument is continuously determined, and a set of latitude, longitude and altitude data is collected before and after the time when the position accuracy requirement is met; wherein the position accuracy requirement is met when the PDOP value is between 1 and 2.

[0012] Furthermore, the preset time before and after refers to a set of latitude, longitude, and altitude data before and after 2 seconds to meet the position accuracy requirements.

[0013] Furthermore, the collected location information is transformed to obtain the three-dimensional coordinates of the carrier in the geocentric coordinate system, including:

[0014] The conversion formula for latitude, longitude, and altitude data at a certain moment is as follows:

[0015] x = Recos(La)cos(Lo)

[0016] y = Recos(La)sin(Lo)

[0017] x = Recos(La) + h

[0018] Where Re is the average radius of the Earth, La and Lo are the latitude and longitude of the carrier's location, h is the altitude, and (x,y,z) are the three-dimensional coordinates of the carrier in the geocentric coordinate system at that moment after the transformation.

[0019] Furthermore, the heading angle of the vehicle is determined based on this three-dimensional coordinate system, including:

[0020] For the collected latitude, longitude, and altitude data, after transformation, corresponding to a set of three-dimensional coordinates (x1, y1, z1) and (x2, y2, z2), the relative displacement vector between the two is first calculated using the following formula:

[0021] Δx=x2-x1

[0022] Δy=y2-y1

[0023] Then, the magnitude is calculated based on the relative displacement vector, and the heading angle is determined. This heading angle is the carrier heading angle that the satellite positioning instrument quickly calculates. The calculation formula is:

[0024]

[0025] Furthermore, the inertial navigation system performs precise alignment over a preset time period based on the carrier's heading angle and a filtering algorithm, including:

[0026] The calculated carrier heading angle is used as the initial heading angle for fine alignment. The horizontal attitude angle is calculated using the output of the accelerometer, and then enters the Kalman filter loop for fine alignment.

[0027] Furthermore, the fine alignment time is 5 to 10 minutes, and can be terminated at any time as needed to switch to navigation calculation.

[0028] A terminal device includes a processor, a memory, and a computer program stored in the memory; when the processor executes the computer program, it implements the method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation in a marine environment.

[0029] A computer-readable storage medium storing a computer program; when executed by a processor, the computer program implements the method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment.

[0030] Compared with the prior art, the present invention has the following technical features:

[0031] 1. Rapid self-north finding: It eliminates the coarse alignment stage in traditional inertial navigation self-north finding, and quickly calculates the approximate heading of the vehicle using the position information of the satellite positioning instrument. It only takes 2 seconds, which greatly shortens the self-north finding time. Compared with the traditional "coarse alignment + fine alignment" scheme, it can save more than 175 seconds of alignment time.

[0032] 2. Unaffected by the dynamic motion of the carrier: Traditional inertial navigation systems are greatly affected by the complex dynamic motion of ships, while the method of satellite positioning instruments to calculate the heading angle is not affected by the dynamic motion of the carrier, thus improving the accuracy and reliability of self-north finding.

[0033] 3. Applicable to marine environments: It is particularly suitable for, but not limited to, situations in marine environments where the inertial navigation alignment time is critical. It can effectively address the adverse effects of various complex six-degree-of-freedom dynamic motions experienced by ships in marine environments, such as pitch, roll, and heave, on the inertial navigation system's self-north-finding. The calculated heading angle is unaffected by the dynamic motion of the carrier, meeting the needs of rapid navigation for ships and other carriers.

[0034] 4. Low cost: This scheme has no special requirements for satellite positioning equipment. It can directly use the single-antenna satellite positioning equipment in the traditional inertial navigation in-flight self-north-finding scheme. While shortening the alignment time, it does not affect the convergence accuracy of fine alignment, nor does it increase the system cost.

[0035] 5. High accuracy: Compared to using satellite positioning speed information, using position information to determine the vehicle's heading is more accurate. Attached Figure Description

[0036] Figure 1 This is a comparison chart of the self-north-finding time of the present invention and the self-north-finding time of the traditional inertial navigation system;

[0037] Figure 2 This is a diagram illustrating the accuracy error of the rapid self-north-finding heading angle of this invention.

[0038] Figure 3 for Figure 2 GPS latitude curve over a given time period;

[0039] Figure 4 for Figure 2 GPS longitude curve over a given time period;

[0040] Figure 5 for Figure 2 GPS altitude curve over a given time period;

[0041] Figure 6 for Figure 2 GPS PDOP value curve over a given time period. Detailed Implementation

[0042] This invention provides a rapid self-north finding method for inertial navigation systems (INS) assisted by a single-antenna satellite positioning system in marine environments. Applied to the rapid self-north finding of INS systems on ships, unmanned surface vessels, and other vessels in marine environments, this method aims to solve the problems of long alignment time and significant influence from vehicle motion in traditional self-north finding methods in complex and dynamic marine environments, thereby improving navigation accuracy and reliability. Furthermore, this invention is closely related to the technical fields of INS systems, satellite positioning technology, and data fusion algorithms. This method rapidly calculates the approximate heading angle of the vehicle using the position information of the satellite positioning system in just 2 seconds, thus eliminating the coarse alignment stage in traditional INS self-north finding and significantly shortening the self-north finding time. By determining whether the PDOP value is between 1 and 2 when data is collected, the calculation accuracy is ensured, providing efficient and accurate navigation support for marine navigation.

[0043] See Figure 1 The present invention provides a method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment, comprising:

[0044] Establish a process for a carrier to seek north while in motion in a marine environment, including a satellite positioning system warm-up phase, a phase of determining the carrier's course using satellite positioning system position information, and a fine alignment phase, wherein:

[0045] When performing automatic north-finding, the satellite positioning device first enters the hot start phase, waiting for the satellite positioning device to complete the hot start.

[0046] In the stage of determining the vehicle's heading using the satellite positioning system's position information, the position accuracy attenuation factor of the satellite positioning system is first judged. Based on the judgment result, the timing for collecting the position information provided by the satellite positioning system is determined. The collected position information is then transformed into coordinates to obtain the three-dimensional coordinates of the vehicle in the geocentric coordinate system. Based on these three-dimensional coordinates, the heading angle of the vehicle is determined.

[0047] During the fine alignment phase, the inertial navigation system performs fine alignment for a preset time period based on the carrier's heading angle and a filtering algorithm, thereby achieving automatic north-finding.

[0048] 1. Satellite positioning device hot start-up phase.

[0049] This solution first performs a satellite definition warm start, such as... Figure 1 As shown, in one embodiment of the present invention, the time T1 required for this stage is 10s.

[0050] Unlike existing technologies, this invention does not employ conventional methods in the field, omitting the coarse alignment stage in traditional inertial navigation self-north-finding methods, which often takes approximately 3 minutes to estimate the approximate heading of the vehicle. The approach of this solution is to directly calculate the approximate heading of the vehicle using the position information from a satellite positioning device, requiring only 2 seconds; and it directly utilizes the single-antenna satellite positioning device found in traditional inertial navigation self-north-finding schemes, without requiring additional equipment.

[0051] 2. Determining the vehicle's heading using satellite positioning information.

[0052] In this stage, the PDOP value (Position Accuracy Attenuation Factor; the square root of the sum of squares of the distance measurement errors in the latitude, longitude and elevation directions) of the satellite positioning instrument is continuously judged first, and a set of latitude, longitude and elevation data is collected 2 seconds before and after the time when the position accuracy requirement is met; wherein the position accuracy requirement is met means that the PDOP value is between 1 and 2, at which time the position accuracy is optimal.

[0053] The collected latitude, longitude, and altitude data are converted into three-dimensional coordinates in the geocentric coordinate system (ECEF). The conversion formula for latitude, longitude, and altitude data at a specific moment is as follows:

[0054] x = Recos(La)cos(Lo)

[0055] y = Recos(La)sin(Lo)

[0056] x = Recos(La) + h

[0057] Where Re is the average radius of the Earth, La and Lo are the latitude and longitude of the carrier's location, h is the altitude, and (x,y,z) are the three-dimensional coordinates of the carrier in the geocentric coordinate system at that moment after the transformation.

[0058] For the three-dimensional coordinates (x1, y1, z1) and (x2, y2, z2) corresponding to the collected latitude, longitude, and altitude data after transformation, the relative displacement vector between the two is first calculated using the following formula:

[0059] Δx=x2-x1

[0060] Δy=y2-y1

[0061] Δz=z2-z1

[0062] Then, the magnitude is calculated based on the relative displacement vector, and the heading angle is determined. This heading angle is the carrier heading angle that the satellite positioning instrument quickly calculates. The calculation formula is:

[0063]

[0064] 3. Precision alignment stage.

[0065] During the fine alignment phase, the calculated carrier heading angle is used as the initial heading angle for fine alignment. The horizontal attitude angles (pitch and roll angles) can be quickly calculated using the output of the accelerometer, allowing them to enter the Kalman filter loop for fine alignment. The fine alignment time is set according to the actual situation, with a recommended time of 5 to 10 minutes. It can be terminated at any time as needed and switched to navigation calculation.

[0066] Example:

[0067] Start the satellite positioning device and inertial navigation system: Power on the satellite positioning device and inertial navigation system. After 40 seconds, the satellite positioning device will complete satellite acquisition and positioning.

[0068] Determine the PDOP value: Monitor the PDOP value of the satellite positioning instrument in real time. The position accuracy is optimal when the PDOP value is between 1 and 2. At this time, collect latitude, longitude and altitude data at intervals of 2 seconds.

[0069] Coordinate transformation: Converting latitude and longitude data provided by satellite positioning instruments into three-dimensional coordinates in the geocentric coordinate system (ECEF).

[0070] For example, at a certain moment, the latitude and longitude data provided by the satellite positioning instrument are:

[0071] Given latitude La = 34.171698°, longitude Lo = 108.923654°, altitude h = 2.2 meters, and Earth's average radius Re = 6371000 meters, the corresponding ECEF coordinates are (-1.708812.04, 4986591.92, 3578198.35). Two seconds later, the satellite positioning system provides latitude and longitude data again. Assuming the latitude La = 34.171712°, longitude Lo = 108.923688°, and altitude h = 2.1 meters, the corresponding ECEF coordinates are (-1.708814.72, 4986590.08, 3578199.64).

[0072] Calculate the heading angle of the vehicle:

[0073]

[0074] At this point, the heading angle calculated by the satellite positioning instrument is 34.474753°.

[0075] Fine alignment phase: The heading angle of 34.474753° calculated by the satellite positioning instrument is used as the initial heading angle for fine alignment. During this period, the inertial navigation system smooths the output of the accelerometer to estimate the horizontal attitude angles (pitch angle and roll angle) of the carrier. The fine alignment time is set to 5-10 minutes and can be terminated at any time according to the actual situation to directly switch to navigation calculation.

[0076] Through the above steps, this invention enables rapid self-north finding of inertial navigation systems in a marine environment, greatly shortening the self-north finding time and improving navigation accuracy and reliability. It is particularly suitable for marine application scenarios with stringent requirements for inertial navigation alignment time, without increasing system costs, and has high practicality and promotional value.

[0077] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application 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 this application, and should all be included within the protection scope of this application.

Claims

1. A method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment, characterized in that: include: Establish a process for a carrier to seek north while in motion in a marine environment, including a satellite positioning system warm-up phase, a phase of determining the carrier's course using satellite positioning system position information, and a fine alignment phase, wherein: When performing automatic north-finding, the satellite positioning device first enters the hot start phase, waiting for the satellite positioning device to complete the hot start. In the stage of determining the carrier's heading using satellite positioning information, the position accuracy attenuation factor of the satellite positioning device is first assessed. Based on the assessment result, the timing for collecting the position information provided by the satellite positioning device is determined, including: The position accuracy attenuation factor of the satellite positioning instrument is continuously determined, and a set of latitude, longitude and altitude data is collected before and after a preset time before and after the moment when the position accuracy requirement is met; wherein the moment when the position accuracy requirement is met refers to when the PDOP value is between 1 and 2; the set of latitude, longitude and altitude data before and after the preset time is a set of latitude, longitude and altitude data before and after the moment when the position accuracy requirement is met. The collected location information is transformed to obtain the three-dimensional coordinates of the carrier in the geocentric coordinate system, including: The conversion formula for latitude, longitude, and altitude data at a certain moment is as follows: in, It is the Earth's average radius. and These are the latitude and longitude of the carrier's location, respectively. It refers to altitude. These are the three-dimensional coordinates of the carrier in the geocentric coordinate system at that moment after the transformation; Determining the vehicle's heading angle based on the three-dimensional coordinates includes: The collected latitude, longitude, and altitude data are transformed into a set of three-dimensional coordinates. and First, calculate the relative displacement vector between the two. The calculation formula is: Then, the magnitude is calculated based on the relative displacement vector, and the heading angle is determined. This heading angle is the carrier heading angle that the satellite positioning instrument quickly calculates. The calculation formula is: During the fine alignment phase, the inertial navigation system performs fine alignment for a preset time period based on the carrier's heading angle and a filtering algorithm, thereby achieving automatic north-finding.

2. The method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment according to claim 1, characterized in that, The inertial navigation system performs precise alignment over a preset time period based on the vehicle's heading angle and a filtering algorithm, including: The calculated carrier heading angle is used as the initial heading angle for fine alignment. The horizontal attitude angle is calculated using the output of the accelerometer and then enters the Kalman filter loop for fine alignment.

3. The method for rapid self-north finding using a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment according to claim 1, characterized in that, The fine alignment time is 5 to 10 minutes, and can be terminated at any time as needed to switch to navigation calculation.

4. A terminal device, comprising a processor, a memory, and a computer program stored in the memory; characterized in that, When the processor executes the computer program, it implements the method for rapid self-north finding of a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment as described in any one of claims 1-3.

5. A computer-readable storage medium storing a computer program; characterized in that, When the computer program is executed by the processor, it implements the method for rapid self-north finding of a single-antenna satellite positioning instrument-assisted inertial navigation system in a marine environment as described in any one of claims 1-3.

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