Underwater single beacon calibration method capable of estimating unknown effective sound speed

A positioning method and sound speed technology, which are applied in the re-radiation of sound waves, navigation calculation tools, and navigation through speed/acceleration measurement, etc., which can solve the problems of positioning accuracy, time-varying unknown, and influence of single-beacon positioning systems.

Active Publication Date: 2020-02-14
HARBIN ENG UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The current underwater single-beacon positioning method usually assumes that the speed of sound in water is completely known, but the actual speed of sound in water is affected by factors such as water temperature, salinity, density, and water depth, and is usually time-varying and unknown.
The setting error of the sound velocity of underwater sound will lead to ranging error, which in turn will affect the positioning accuracy of the single beacon positioning system
However, the existing underwater single-beacon positioning methods based on unknown effective sound velocity all model the uncertainty of effective sound velocity as a Gauss distribution
However, in the actual underwater positioning, due to the influence of the harsh underwater environment, the uncertainty of underwater acoustic sound velocity is usually non-Gauss (it will be affected by factors such as observation outliers)
In this case, the traditional single-beacon positioning method based on Gauss noise to model the uncertainty of underwater acoustic sound velocity has random model modeling errors, which will also affect the performance of the single-beacon positioning system, and then affect its actual application

Method used

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  • Underwater single beacon calibration method capable of estimating unknown effective sound speed
  • Underwater single beacon calibration method capable of estimating unknown effective sound speed
  • Underwater single beacon calibration method capable of estimating unknown effective sound speed

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0165] Embodiment 1, see attached figure 1 , an underwater single-beacon positioning method capable of estimating the unknown effective sound velocity, comprising the following steps:

[0166] A. Take any point in the positioning area as the origin, set the east, north, and sky directions as x, y, and z axes respectively, and establish an underwater local inertial coordinate system;

[0167] B. Obtain the initial position of the underwater vehicle in the underwater local inertial system through the GPS system carried by the underwater vehicle;

[0168] C. Establish the kinematics model and observation model of the underwater vehicle and perform discretization;

[0169] The establishment method of described kinematic model is:

[0170] Define the state vector as:

[0171] x=[x y v cx v cy ] T

[0172] Wherein: x, y are the horizontal positions of the underwater vehicle in the underwater local inertial coordinate system; v cx , v cy is the unknown current velocity;

...

Embodiment 2

[0321] Example 2, using the method described in Example 1 to verify through test data.

[0322] As a comparison, this embodiment also shows the positioning results of the underwater single beacon positioning method based on the Gauss distribution of sound velocity uncertainty and the known steady underwater sound velocity (respectively marked as traditional method 1 and traditional method 2, traditional method 1 refers to Literature Z.Zhu and S.L.J.Hu, "Model and algorithm improvement on single beacon underwater tracking," IEEE Journal of Oceanic Engineering, vol.PP, no.99, pp.1–18, 2017.).

[0323] The method of collecting test data is as follows: the surface ship is equipped with GPS, hydrophone and compass, and performs two-dimensional motion on the water surface. The trajectory of the surface ship observed by GPS is used as a real reference, and the hydrophone receives the underwater acoustic signal emitted by the underwater acoustic beacon fixed on the bottom of the water...

Embodiment 3

[0329] Embodiment 3, the algorithm pseudocode of the present invention is summarized as:

[0330]

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Abstract

The invention belongs to the technical field of underwater positioning, and particularly relates to a single beacon calibration method of an underwater vehicle. When the underwater vehicle does not receive a periodic underwater sound signal, dead reckoning is carried out through a self-equipped electronic compass, a depth meter and propeller rotating speed information read by the underwater vehicle, and after receiving the absolute speed observation measured by a carried Doppler tachymeter, ocean current speed observation amount is constructed and the ocean current speed correction is carriedout through Kalman filtering; after the underwater vehicle receives the underwater sound signal, the unknown effective sound speed is modeled as a Student's t distribution by considering the unknown property of the underwater sound speed, and the position update of the underwater vehicle is carried out based on the extended Kalman filtering algorithm and variational Bayesian approximation by taking the underwater sound signal transmission time as the observation variable. Compared with the underwater single-beacon calibration method based on known fixed and constant effective sound speed and based on sound speed uncertainty for meeting Gauss distribution, more ideal positioning performance can be obtained by the method of the invention, and the actual application capability of an underwater single-beacon positioning system is enhanced.

Description

technical field [0001] The invention belongs to the technical field of underwater positioning, in particular to a single-beacon positioning method for an underwater vehicle. Background technique [0002] Accurate position feedback is the basis for underwater vehicles to complete established underwater tasks. Due to the rapid attenuation of underwater electromagnetic wave signals, the GNSS system, which is widely used in land and sky positioning, cannot be applied underwater. The existing mainstream underwater positioning methods include dead reckoning methods represented by inertial navigation and underwater acoustic positioning methods represented by long baseline positioning. Among them, inertial navigation equipment tends to produce large cumulative errors over time, and cannot be used for underwater positioning for a long time, and high-precision inertial navigation equipment is extremely expensive, which limits its application in underwater vehicles. The existing main...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S15/60G01C21/20G01C21/16
CPCG01C21/165G01C21/203G01S15/60
Inventor 秦洪德余相朱仲本邓忠超万磊田瑞菊
Owner HARBIN ENG UNIV
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