Novel Single-Beam Elevation Sounder and Its Attitude Compensation Method

Abstract

This invention discloses a novel single-beam echo sounder and its attitude compensation method. The single-beam echo sounder integrates a high-precision attitude module, which uses attitude information to calibrate depth and position. The method includes the following steps: controlling the transmission of acoustic waves and collecting seabed echoes using the single-beam echo sounder; GNSS transmits high-precision positioning information and PPS (Precision Per Second) pulses in real time to the wet-end sonar probe, while the probe simultaneously receives attitude information from the built-in attitude module. The above information is then processed comprehensively and uploaded to the dry-end host computer software; the obtained time interval is proportional to the distance from the sonar transducer to the riverbed or seabed; a smoothing window is used for water depth filtering; and attitude, position, pitch, and roll compensation calculations are performed. This invention, with its built-in high-precision attitude module, integrates high-precision GNSS information and PPS high-precision pulses, significantly improving both depth sounding and positioning accuracy.

Description

Technical Field

[0001] This invention relates to the fields of underwater acoustic imaging and marine mapping, and in particular to a novel single-beam echo sounder and its attitude compensation method. Background Technology

[0002] Sonar is a device that uses the principle of echo sounding to detect underwater environments and objects. Traditional single-beam echo sounders emit sound waves downwards and obtain the water depth by detecting the received echoes.

[0003] Traditional single-beam echo sounders have a relatively simple composition. The sonar probe only contains a transducer, while the electronic system and display / control module are located in the ship's bridge or work area. Traditional single-beam echo sounders lack attitude modules and do not compensate for the ship's sound velocity profile, resulting in relatively low depth-sounding and positioning accuracy. In recent years, some single-beam echo sounders have been equipped with attitude modules or inertial navigation systems, but these attitude devices are generally located on the ship and are not rigidly connected to the probe, meaning the attitude data cannot accurately reflect changes in the probe's attitude. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings, the purpose of this invention is to provide a novel single-beam echo sounder and its attitude compensation method, which integrates a high-precision attitude module built into the probe, accesses high-precision GNSS information and PPS high-precision second pulses, and greatly improves depth sounding accuracy and positioning accuracy.

[0005] To achieve the above objectives, one of the technical solutions adopted by the present invention is: a novel single-beam echo sounder, wherein the single-beam echo sounder integrates a high-precision attitude module, and the high-precision attitude module uses attitude information to calibrate depth and position.

[0006] To achieve the above objectives, another technical solution adopted by the present invention is: a novel attitude compensation method for a single-beam echo sounder, employing the aforementioned novel single-beam echo sounder, comprising the following steps:

[0007] Step 1: Use a single-beam echo sounder to control the transmission of sound waves and collect seabed echoes;

[0008] Step 2: GNSS transmits high-precision positioning information and PPS second pulses to the sonar wet end probe in real time. The probe also receives attitude information from the built-in attitude module and processes the above information in a comprehensive manner.

[0009] Step 3: The probe packages and uploads sonar data, positioning data, attitude data, time information, etc., to the host computer software at the dry end;

[0010] Step 4: When the depth sounder emits sound waves downwards, the emission is strongest at the riverbed or seabed. At this time, take the maximum amplitude or maximum energy of the sound wave signal processing result, or use other strategies to calculate. The resulting time interval is proportional to the distance from the sonar transducer to the riverbed or seabed.

[0011] Step 5: The riverbed or seabed has flat characteristics. The correlation between the water depth values ​​obtained by adjacent beams is used for filtering, that is, water depth filtering is performed using a smoothing window.

[0012] Step six: Perform attitude compensation;

[0013] Step 7: Perform position compensation. When a large attitude deviation occurs, the actual water depth measured is not the water depth directly below the sonar because the beam footprint of the sonar is not directly below the sonar, but rather the water depth diagonally below the sonar. At this time, it is necessary to compensate the current position of the sonar to the actual position of the beam footprint.

[0014] Step 8: Perform pitch compensation calculation;

[0015] Step nine: Perform roll compensation calculation.

[0016] Preferably, the attitude compensation method in step six is ​​as follows: First, determine the current attitude angle (pitch angle θ). p and roll angle θ r Is it less than half the opening angle of the sound wave beam? Under the flat-bottom assumption, when the attitude angle is less than half the beam opening angle, the main beam of the sound wave can still illuminate directly below the sonar, and attitude compensation is not required. If the attitude angle is greater than half the beam opening angle, attitude compensation is necessary. In this case, the inner edge of the main beam illuminates the point closest to directly below, which is the point with the shortest sound path. The angle between the inner edge and the vertical line is... Taking the pitch angle as an example, the corrected water depth is:

[0017]

[0018] If the roll angle is also greater than Then there is

[0019]

[0020] In summary:

[0021]

[0022]

[0023] Preferably, the position compensation in step eight is used to compensate the current position of the sonar to the actual position of the beam footprint.

[0024] Preferably, the sonar's planar coordinate system is (E1, N1), where E1 is the east coordinate, N1 is the north coordinate, and the sonar's heading is θ. H The formula for pitch compensation is:

[0025]

[0026] Preferably, the formula for the roll compensation is:

[0027]

[0028] Preferably, the algorithm that obtains the time interval proportional to the distance from the sonar transducer to the riverbed or seabed is as follows:

[0029]

[0030] Where C is the speed of sound in water, t max This refers to the moment when the amplitude reaches its maximum value (taking the maximum amplitude strategy as an example).

[0031] The beneficial effects of the novel single-beam echo sounder and its attitude calibration method are as follows:

[0032] (1) The wet end probe has a built-in high-precision attitude module, which makes the attitude module and the transducer always rigidly connected, avoiding the problem of inaccurate attitude measurement caused by non-rigid connection in traditional applications, and greatly improving the effectiveness of attitude measurement.

[0033] (2) Using attitude information for depth calibration, considering the edge beams of the main lobe of the acoustic beam rather than the center beam, the calibration results are more accurate.

[0034] (3) The location information is calibrated to reduce the impact of uneven bottom. Detailed Implementation

[0035] The preferred embodiments of the present invention will now be described in detail so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0036] This embodiment presents a novel single-beam echo sounder that integrates a high-precision attitude module. The high-precision attitude module uses attitude information to calibrate depth and position.

[0037] This embodiment presents a novel attitude compensation method for a single-beam echo sounder. The method utilizes the aforementioned novel single-beam echo sounder, and its operational steps are as follows:

[0038] Step 1: Use a single-beam echo sounder to control the transmission of sound waves and collect seabed echoes;

[0039] Step 2: GNSS transmits high-precision positioning information and PPS second pulses to the sonar wet end probe in real time. The probe also receives attitude information from the built-in attitude module and processes the above information in a comprehensive manner.

[0040] Step 3: The probe packages and uploads sonar data, positioning data, attitude data, time information, etc., to the host computer software at the dry end;

[0041] Step four: When the depth sounder emits sound waves downwards, the emission is strongest at the riverbed or seabed. At this point, the maximum amplitude or maximum energy value of the processed sound wave signal is taken, or other strategies are used for calculation. The resulting time interval is proportional to the distance from the sonar transducer to the riverbed or seabed. Specifically, it is...

[0042]

[0043] Where C is the speed of sound in water, t max This refers to the moment when the amplitude reaches its maximum value (using the maximum amplitude strategy as an example).

[0044] Step 5: Since the riverbed or seabed is generally relatively flat and there will be no drastic changes, there is a certain correlation between the water depth values ​​obtained by adjacent beams. This correlation can be used for filtering. One method is to use a smoothing window for water depth filtering.

[0045] Step six, the attitude compensation method is as follows: First, determine the current attitude angle (pitch angle θ). p and roll angle θ r Is it less than half the opening angle of the sound wave beam? Under the flat-bottom assumption, when the attitude angle is less than half of the beam opening angle, the main beam of the sound wave can still illuminate directly below the sonar, and attitude compensation is not required.

[0046] Step 7: If the attitude angle is greater than half of the acoustic beam opening angle, attitude compensation is required. At this point, the inner edge of the main beam illuminates the point closest to directly below, which is the illumination point with the shortest sound path. The angle between the inner edge and the vertical line is... (Using pitch angle as an example).

[0047] The corrected water depth is now:

[0048]

[0049] If the roll angle is also greater than Then there is

[0050]

[0051] In summary:

[0052]

[0053]

[0054] Step 8, Position Compensation. When a large attitude shift occurs, the actual water depth measured will not be the water depth directly below the sonar, but rather the water depth diagonally below the sonar, because the beam footprint of the sonar is not directly below the sonar. In this case, it is necessary to compensate the current position of the sonar to the actual position of the beam footprint.

[0055] Step 9: Let the sonar's plane coordinate system be (E1, N1), where E1 is the east coordinate, N1 is the north coordinate, and the sonar's heading is θ. H ;

[0056] Step 10, the formula for pitch compensation is as follows:

[0057]

[0058] Step eleven, the formula for roll compensation is as follows:

[0059]

[0060] The above completes the attitude calibration, including depth calibration and position calibration.

[0061] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A novel single-beam bathymetric attitude compensation method, characterized in that: The application relates to a new single-beam depth sounder, which is internally integrated with a high-precision attitude module, the high-precision attitude module calibrates the depth and position by using attitude information, and comprises the following steps. Step one: the single-beam depth sounder is used to control the emission of sound waves and collect seabed echoes; Step two: GNSS transmits positioning information and PPS second pulses to a sonar wet-end probe in real time, the probe also receives attitude information of the built-in attitude module, and the information is comprehensively processed; Step three: the probe uploads sonar data, positioning data, attitude data and time information to a dry-end host computer software; Step four: when the depth sounder emits sound waves downward, the strongest emission is obtained on the river bottom or the seabed, at this time, the amplitude maximum value or the energy maximum value of the sound wave signal processing result is obtained, and the obtained time interval is proportional to the distance from the sonar transducer to the river bottom or the seabed; Step five: the river bottom or the seabed has a flat characteristic, the correlation between the water depth values obtained by adjacent beams is used for filtering processing, that is, a smoothing window is used for water depth filtering; Step six: attitude compensation is carried out; Step seven: position compensation is carried out, when a large attitude deviation occurs, the actually measured water depth is the water depth of the oblique lower side of the sonar, the current position of the sonar is compensated to the actual position of the beam footprint; Step eight: pitch compensation calculation is carried out; Step nine: roll compensation calculation is carried out; The attitude compensation method in the step six is as follows: First, it is judged whether the current attitude angle, i.e. the pitch angle θ p and the roll angle θ r is less than half of the opening angle of the acoustic wave beam Under the flat bottom assumption condition, when the attitude angle is less than half of the beam opening angle, the main beam of the sound wave can still irradiate to the lower side of the sonar, at this time, the attitude compensation is not needed; If the attitude angle is greater than half of the opening angle of the acoustic beam, the attitude needs to be compensated, at this time the inner edge of the main beam is irradiated to the nearest point below the distance, which is the shortest irradiation point of the sound path, and the intersection angle between the inner edge and the plumb line is Take the pitch angle as an example, at this time the corrected water depth is: If the roll angle is also greater than then: Comprehensively, it is: The position compensation in the step seven is used to compensate the current position of the sonar to the actual position of the beam footprint; The algorithm of the step eight's pitch compensation is: let the plane coordinate system of the sonar be (E1, N1), wherein E1 is east coordinate, N1 is north coordinate, the heading of the sonar be θ H The algorithm of the pitch compensation is: The roll compensation formula is:

2. The novel single-beam bathymeter attitude compensation method according to claim 1, characterized in that: The algorithm that the obtained time interval is proportional to the distance from the sonar transducer to the river bottom or the seabed is: where C is the sound speed in water, t max is the time at which the amplitude reaches a maximum.

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