Single-antenna satellite positioning system assisted inertial navigation rapid self-north-seeking method in marine environment

Abstract

The invention discloses a single-antenna satellite positioning system assisted inertial navigation rapid self-north-seeking method in a marine environment, which comprises the following steps: during automatic north seeking, firstly entering a satellite positioning system hot start stage, and waiting for the satellite positioning system to finish hot start; in the stage of determining the course of the carrier by using the position information of the satellite positioning instrument, firstly, the position precision attenuation factor of the satellite positioning instrument is judged, the opportunity for collecting the position information provided by the satellite positioning instrument is determined based on the judgment result, and coordinate transformation is performed on the collected position information; obtaining a three-dimensional coordinate of the carrier in the geocentric coordinate system, and determining a course angle of the carrier based on the three-dimensional coordinate; and in the fine alignment stage, the inertial navigation system performs fine alignment in a preset time period based on the carrier course angle by combining a filtering algorithm, so that an automatic north-seeking process is realized. According to the invention, the problems of long alignment time, great influence of carrier motion and the like of a traditional automatic north-seeking method in a complex dynamic ocean environment are solved, and the navigation precision and reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of marine navigation technology, in particular to a single antenna satellite positioning instrument assisted inertial navigation rapid self-orientation method in marine environment. BACKGROUND

[0002] In marine environment, the self-orientation process of inertial navigation system during travel is crucial for the navigation of carrier such as ship. The traditional inertial navigation self-orientation method during travel usually adopts the scheme of "rough alignment + fine alignment", the rough alignment needs 3 minutes to roughly estimate the approximate heading and horizontal attitude of the carrier, and the initial attitude of fine alignment depends on the attitude value estimated at the end of rough alignment, and the whole alignment process takes a long time (usually 5-10 minutes). However, in marine environment, the ship will experience complex dynamic motion, including pitch, roll, heave and other six degrees of freedom motion, which will cause the attitude angle estimated by rough alignment to deviate, and if the error angle of rough alignment is large (more than 5 degrees), it will affect the estimation effect of fine alignment, and further reduce the initial alignment accuracy. Therefore, how to quickly and accurately complete the self-orientation of inertial navigation in marine environment is a technical problem to be solved. SUMMARY

[0003] The purpose of the present application is to provide a single antenna satellite positioning instrument assisted inertial navigation rapid self-orientation method in marine environment, which aims to solve the problems of long alignment time and large influence of carrier motion of traditional self-orientation method in complex dynamic environment of marine, and improve the navigation accuracy and reliability.

[0004] In order to achieve the above task, the present application adopts the following technical scheme:

[0005] The single antenna satellite positioning instrument assisted inertial navigation rapid self-orientation method in marine environment comprises:

[0006] The process of self-orientation of carrier in marine environment during travel is established, including satellite positioning instrument warm-up stage, carrier heading determination stage using satellite positioning instrument position information and fine alignment stage, wherein:

[0007] When performing automatic self-orientation, first enter the satellite positioning instrument warm-up stage, and wait for the satellite positioning instrument to complete the warm-up;

[0008] In the carrier heading determination stage using satellite positioning instrument position information, first judge the position accuracy decay factor of satellite positioning instrument, determine the timing of collecting the position information provided by satellite positioning instrument based on the judgment result, and perform coordinate conversion on the collected position information to obtain the three-dimensional coordinates of carrier in the earth-centered coordinate system, and determine the carrier heading angle based on the three-dimensional coordinates;

[0009] In the fine alignment stage, the inertial navigation system combines a filtering algorithm with the heading angle of the carrier to perform fine alignment for a preset time period, thereby realizing the automatic north-seeking process.

[0010] Further, the position accuracy decay factor of the satellite positioning instrument is judged, and based on the judgment result, the timing of collecting the position information provided by the satellite positioning instrument is determined, including:

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

[0012] Further, the preset time before and after is a set of longitude, latitude and height data 2s before and after the timing when the position accuracy requirement is met.

[0013] Further, the collected position information is converted to coordinates to obtain the three-dimensional coordinates of the carrier in the geocentric coordinate system, including:

[0014] For the longitude, latitude and height data at a certain time, the conversion formula is as follows:

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

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

[0017] x=Recos(La)+h

[0018] Wherein, Re is the average radius of the earth, La and Lo are the latitude and longitude of the position of the carrier respectively, h is the altitude, (x, y, z) is the three-dimensional coordinates of the carrier in the geocentric coordinate system after conversion at that time.

[0019] Further, based on the three-dimensional coordinates, the heading angle of the carrier is determined, including:

[0020] For a set of three-dimensional coordinates (x1, y1, z1) and (x2, y2, z2) corresponding to the collected longitude, latitude and height data after conversion, first calculate the relative displacement vector of the two, the calculation formula is:

[0021] Δx=x2-x1

[0022] Δy=y2-y1

[0023] Then calculate the length based on the relative displacement vector and determine the direction angle, which is the heading angle of the carrier calculated quickly by the satellite positioning instrument The calculation formula is:

[0024]

[0025] Further, the inertial navigation system is based on the carrier heading angle, and a preset time period is combined with a filtering algorithm for fine alignment, including:

[0026] The calculated carrier heading angle is used as the initial heading angle for fine alignment, and the horizontal attitude angle is calculated by using the output of the accelerometer, so that the kalman filtering loop can be entered for fine alignment.

[0027] Further, the time for fine alignment is 5-10 minutes, which can be terminated at any time and converted into 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, the method for single-antenna satellite positioning instrument assisted inertial navigation fast self-orientation in the marine environment is realized.

[0029] A computer readable storage medium, the medium stores a computer program; when the computer program is executed by the processor, the method for single-antenna satellite positioning instrument assisted inertial navigation fast self-orientation in the marine environment is realized.

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

[0031] 1. Fast self-orientation: The coarse alignment phase in the traditional inertial navigation self-orientation is omitted, and the approximate heading of the carrier is quickly calculated using the position information of the satellite positioning instrument, only 2s are required, which greatly shortens the self-orientation time, and compared with the traditional "coarse alignment + fine alignment" scheme, the alignment time can be saved by more than 175s.

[0032] 2. Not affected by the dynamic motion of the carrier: The traditional inertial navigation self-orientation is greatly affected by the complex dynamic motion of the ship, while the method of calculating the heading angle by the satellite positioning instrument is not affected by the dynamic motion of the carrier, which improves the accuracy and reliability of the self-orientation.

[0033] 3. Suitable for marine environment: Especially suitable for but not limited to the case where the inertial navigation alignment time is harsh in the marine environment, which can effectively deal with the adverse effects of the inertial navigation self-orientation of the ship in the marine environment under the complex dynamic motion of the six degrees of freedom such as pitching, rolling, and heaving, and the calculated heading angle is not affected by the dynamic motion of the carrier, which meets the demand of fast navigation of the carrier such as the ship.

[0034] 4. Low cost: This scheme has no special requirements for the satellite positioning instrument, and directly uses the single-antenna satellite positioning instrument in the traditional inertial navigation self-orientation scheme, which shortens the alignment time without affecting the convergence accuracy of the fine alignment and increasing the system cost.

[0035] 5. High precision: Compared with using the speed information of the satellite positioning instrument to determine the carrier heading, the precision is higher. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The figure is a comparison chart of the quick self-orientation time of the application and the traditional inertial navigation self-orientation time;

[0037] Figure 2 The figure is a precision error chart of the quick self-orientation heading angle of the application;

[0038] Figure 3 The figure is a GPS latitude curve in a time period of Figure 2

[0039] The figure is a GPS longitude curve in a time period of Figure 4 Figure 2 The figure is a GPS height curve in a time period of Figure 2

[0040] Figure 5 The figure is a GPS PDOP value curve in a time period of Figure 2 Figure 2

[0041] Figure 6 Figure 2 DETAILED DESCRIPTION

[0042] The application provides a single-antenna satellite positioning instrument assisted inertial navigation quick self-orientation method in a marine environment, which is applied to the quick self-orientation of an inertial navigation system of a carrier such as a ship or an unmanned ship in a marine environment, aims to solve the problems of long alignment time and great influence of carrier movement of the traditional self-orientation method in a complex dynamic marine environment, and improve the navigation precision and reliability. Meanwhile, the application is closely related to the technical fields of inertial navigation systems, satellite positioning technologies and data fusion algorithms, the method quickly calculates the approximate heading angle of the carrier through the position information of the satellite positioning instrument, only needs 2s, thereby omitting the coarse alignment stage in the traditional inertial navigation self-orientation, greatly shortening the self-orientation time; the data acquisition is performed by judging the PDOP value between 1 and 2, thereby ensuring the calculation precision; and the application provides efficient and accurate navigation support for marine navigation.

[0043] Referring to Figure 1 , the application provides a single-antenna satellite positioning instrument assisted inertial navigation quick self-orientation method in a marine environment, which comprises the following steps:

[0044] The application establishes a process of self-orientation of the carrier in the marine environment, which comprises a satellite positioning instrument hot start stage, a carrier heading stage of determining the carrier heading through the position information of the satellite positioning instrument and a fine alignment stage, wherein:

[0045] When the automatic self-orientation is performed, the satellite positioning instrument hot start stage is first entered, and the satellite positioning instrument is waited to complete the hot start;

[0046] ​​In the stage of determining the carrier heading by using the position information of the satellite positioning instrument, firstly, the position accuracy attenuation factor of the satellite positioning instrument is judged, the time for collecting the position information provided by the satellite positioning instrument is determined based on the judgment result, and the collected position information is converted in coordinates to obtain the three-dimensional coordinates of the carrier in the earth-centered coordinate system, and the carrier heading angle is determined based on the three-dimensional coordinates.

[0047] In the fine alignment stage, the inertial navigation system performs fine alignment for a preset time period based on the carrier heading angle and in combination with a filtering algorithm, so as to realize the automatic north-seeking process.

[0048] 1. Hot start stage of the satellite positioning instrument.

[0049] In the present scheme, the satellite positioning instrument is first started hot, as shown in FIG. 1, and the time T1 required in this stage is 10 s in an embodiment of the present application. Figure 1

[0050] Unlike the prior art, the present application does not use the conventional method in the field, i.e., the coarse alignment stage in the conventional inertial navigation self-north-seeking method is omitted, because this stage often needs to consume about 3 min to estimate the approximate heading of the carrier. The idea of the present scheme is to directly calculate the general heading of the carrier by using the position information of the satellite positioning instrument, which only needs 2 s, and a single-antenna satellite positioning instrument in the conventional inertial navigation self-north-seeking scheme during travel can be directly used, without the need for additional equipment.

[0051] 2. Stage of determining the carrier heading by using the position information of the satellite positioning instrument.

[0052] In this stage, firstly, the PDOP value (position accuracy attenuation factor; the square root value of the sum of the square of the ranging errors in the latitude, longitude and altitude directions) of the satellite positioning instrument is continuously judged, and a group of latitude, longitude and altitude data before and after 2 s when the position accuracy requirement is met is collected; wherein the position accuracy requirement refers to the PDOP value being between 1 and 2, at which time the position accuracy is best.

[0053] For the collected latitude, longitude and altitude data, the three-dimensional coordinates in the earth-centered coordinate system (ECEF) are converted; wherein for the latitude, longitude and altitude data at a certain time, the conversion formula is as follows:

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

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

[0056] x=Recos(La)+h

[0057] wherein Re is the average radius of the earth, La and Lo are the latitude and longitude of the position of the carrier respectively, h is the altitude, and (x, y, z) are the three-dimensional coordinates of the carrier in the earth-centered coordinate system at the time after conversion.​

[0058] For the corresponding set of three-dimensional coordinates (x1, y1, z1) and (x2, y2, z2) after conversion of the collected longitude and latitude data, first calculate the relative displacement vector of the two, the calculation formula is:

[0059] Δx = x2 - x1

[0060] Δy = y2 - y1

[0061] Δz = z2 - z1

[0062] Then calculate the length based on the relative displacement vector and determine the direction angle, which is the carrier heading angle calculated quickly by the satellite positioning instrument The calculation formula is:

[0063]

[0064] 3. Fine alignment phase.

[0065] In the fine alignment phase, the calculated carrier heading angle is used as the initial heading angle for fine alignment, and the horizontal attitude angle (pitch angle and roll angle) can be quickly calculated with the output of the accelerometer, so that the kalman filter loop can be entered for fine alignment; The fine alignment time is set according to the actual situation, recommended for 5-10 minutes, which can be terminated at any time according to the needs and transferred to the navigation solution.

[0066] Embodiment:

[0067] Start the satellite positioning instrument and the inertial navigation system: power on the satellite positioning instrument and the inertial navigation system, and the satellite positioning instrument completes the satellite search and positioning after 40s.

[0068] Determine the PDOP value: monitor the PDOP value of the satellite positioning instrument in real time, when the PDOP value is between 1 and 2, the position accuracy is best, at this time, collect the longitude and latitude data before and after 2s respectively.

[0069] Coordinate conversion: convert the longitude and latitude data provided by the satellite positioning instrument into three-dimensional coordinates in the Earth-Centered Earth-Fixed (ECEF) coordinate system.

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

[0071] Latitude La=34.171698°, longitude Lo=108.923654°, altitude h=2.2 meters, the average radius of the earth Re=6371000 meters, then the corresponding ECEF coordinates are (-1.708812.04, 4986591.92, 3578198.35); 2s later, the satellite positioning instrument provides longitude and latitude data again, assuming that the latitude La=34.171712°, the longitude Lo=108.923688°, the altitude h=2.1 meters, then the corresponding ECEF coordinates are (-1.708814.72, 4986590.08, 3578199.64).

[0072] The heading angle of the carrier is calculated:

[0073]

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

[0075] The fine alignment phase: taking the heading angle 34.474753° calculated by the satellite positioning instrument as the initial heading angle of fine alignment to perform fine alignment; the inertial navigation system estimates the horizontal attitude angle (pitch angle and roll angle) of the carrier by smoothing the output of the accelerometer in this time period, and the fine alignment time is set to 5-10 minutes, which can be terminated at any time and directly converted into navigation calculation.

[0076] Through the above steps, the inertial navigation self-azimuth finding is realized in the marine environment, the self-azimuth finding time is greatly shortened, the navigation accuracy and reliability are improved, and it is especially suitable for marine application scenarios with strict requirements on inertial navigation alignment time, without increasing the system cost, and has high practicability and popularization value.

[0077] The above embodiments are only used to illustrate the technical solutions of the present application, but not limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present 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 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. 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 position accuracy attenuation factor of the satellite positioning instrument is determined, and the timing for collecting the position information provided by the satellite positioning instrument is determined based on the determination result, 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 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.

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 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.

4. 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 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: x = Recos(La)cos(Lo) y = Recos(La)sin(Lo) x = Recos(La) + h 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.

5. 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, Determining the vehicle's heading angle based on these three-dimensional coordinates includes: 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: Δx=x2-x1 Δy=y2-y1 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:

6. 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.

7. 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.

8. 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 1-7.

9. 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 1-7.

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