A method and system for calculating ship draft

Abstract

This invention relates to the field of ship draft calculation technology, and provides a method for calculating ship draft using side-scan sonar to calculate the draft of inland waterway bulk carriers. The method includes the following steps: S1: Installing a side-scan sonar on the bottom of one side of the waterway, the side-scan sonar continuously emitting a sound beam towards the water surface 24 hours a day; S2: When the side-scan sonar receives a strong echo signal generated by the ship's hull against the sound beam, it is determined that a ship target has appeared; S3: Based on the sonar data received by the side-scan sonar, finding the sampling points of the strong reflection signal at the intersection of the ship's hull and the water surface, and the strong reflection signal at the bilge, and calculating the ship's draft value in conjunction with the installation depth of the side-scan sonar.

Description

Technical Field

[0001] This invention relates to the technical field of ship draft calculation, and in particular to a method and system for ship draft calculation, which uses side-scan sonar to calculate the draft of inland waterway bulk carriers. Background Technology

[0002] Overloading of vessels can easily lead to grounding in waterways, causing rapid siltation and potentially damaging the waterway, resulting in property damage and casualties. With the increasing volume of inland waterway transport, critical information such as vessel draft cannot be effectively verified, leading to frequent violations such as falsely reporting or concealing the loaded draft, seriously threatening navigation order and safety.

[0003] Side-scan sonar is a detection device that uses the principle of echo detection to detect the acoustic structure and properties of the water surface, sea surface, and seabed by emitting sound waves. A transducer array is installed on each side of the towed fish of a side-scan sonar. It emits sound pulses that propagate outwards. When these pulses encounter objects on the seabed or in the water, they are scattered. The backscattered sound waves return along their original propagation path to the transducer array and are received by the transducers. The side-scan sonar maps the received echo signals point-by-point according to their arrival time, and then arranges and displays the signals received in each transmission cycle to form an acoustic map.

[0004] It is known that when a sound wave propagates from medium 1 to medium 2, reflection, scattering, and refraction occur at the interface between the media. Let the acoustic impedances of medium 1 and medium 2 be Z1 = ρ1c1 and Z2 = ρ2c2, respectively, and the angle of incidence be θ. i The reflection angle is θ r The angle of refraction is θ t The incident sound pressure is P i Then the reflected sound pressure P r and refracted sound pressure P t They are respectively:

[0005]

[0006]

[0007] Let m = c1 / c2, n = ρ2 / ρ1, then by the law of refraction we can obtain:

[0008]

[0009] Substituting equation (3) into equations (1) and (2) respectively, we get:

[0010]

[0011]

[0012] Given that the density of water is ρ1 = 1000 kg / m³3 The speed of sound, c1 = 1500 m / s. The air density, ρ2 = 1.293 kg / m³. 3 The speed of sound, c² = 343 m / s. |P| is calculated from equations (4) and (5). i |=P r P t ≈0. Therefore, it can be concluded that total internal reflection will occur regardless of the angle at which sound waves are emitted from underwater to a calm water surface.

[0013] The hulls of inland bulk carriers are mostly made of steel plates or cement, which cause strong reflections when sound waves are emitted from underwater. This reflection is significantly stronger than the backscattered sound waves generated by surface ripples, floating debris, and other adventitious objects, making it relatively easy to extract ship target information from the acquired sonar signals.

[0014] Inland bulk carriers have a regular hull structure with a flat bottom and vertical side plates. The side plates are connected to the bottom via bilges. When sound waves are emitted obliquely upwards from underwater onto the hull, they are obliquely incident on the side plates, but perpendicularly incident at the hull-water interface and the bilge. This means the backscattered signals at these two locations are much stronger than the echo signals from the side plates. However, because the bilges of bulk carriers are not right-angled but rather have a slightly lofted arc shape, the echo signals at the hull-water interface are stronger than those at the bilges.

[0015] Currently, common methods for detecting vessel draft in inland waterways and ports include manual inspection, laser measurement, and acoustic measurement. Manual inspection typically involves manually reading water gauge readings placed on the ship's side. This requires the vessel to be stationary, resulting in low efficiency and susceptibility to adverse factors such as visibility and water surface fluctuations, leading to large reading errors and potential penalties. Laser measurement is easily affected by environmental factors such as water quality, especially during flood season when turbid water significantly impacts accuracy. Common acoustic measurement methods include ultrasonic ranging and multibeam sonar. Both require sonar equipment to be laid on the bottom of the waterway or installed in the center, making them susceptible to obstruction by underwater sand, silt, and other debris, posing significant challenges to equipment maintenance. Furthermore, these methods have limited monitoring range and are typically only applicable to vessel monitoring within locks. Summary of the Invention

[0016] To address the aforementioned problems, the present invention aims to provide a method and system for calculating the draft of inland bulk carriers that has a large monitoring range and is simple to construct and maintain. Based on the principle of acoustic echo detection, the method utilizes side-scan sonar to automatically detect the draft of inland bulk carriers.

[0017] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0018] A method for calculating the draft of a ship includes the following steps:

[0019] S1: A side-scan sonar is installed at the bottom of one side of the channel, and the side-scan sonar continuously emits sound beams toward the water surface 24 hours a day.

[0020] S2: When the side-scan sonar receives a strong echo signal generated by the ship's hull against the sound beam, it is determined that a ship target has appeared;

[0021] S3: Based on the sonar signals received by the side-scan sonar, locate the sampling points of the strong reflection signals at the intersection of the hull and the water surface and the strong reflection signals at the bilge, and calculate the draft of the hull by combining the installation depth of the side-scan sonar.

[0022] Furthermore, when the bilge has an arc, the lofting radius of the bilge is included in the calculation of the draft.

[0023] Further, in step S3, based on the sonar signal received by the side-scan sonar, the sampling point positions of the strong echo signal at the intersection of the hull and the water surface and the strong echo signal at the bilge are located, and the draft value of the hull is calculated in combination with the installation depth of the side-scan sonar. Specifically:

[0024] Let the installation position of the side-scan sonar be O, the installation depth of the side-scan sonar be H, the horizontal distance between the hull and the side-scan sonar be X0, the lofting radius of the bilge be R, the lofting center of the bilge be P, the intersection of the hull and the water surface be A, the length of OA be L1, the highest point of the strong echo signal of the bilge be the intersection of OP and the bilge be B, the length of OB be L2, and the draft be h.

[0025] Draw a horizontal line through the installation position O of the side-scan sonar, and draw a vertical line through the center of the lofting circle P of the bilge. The intersection of the two lines is recorded as P'.

[0026] According to the Pythagorean theorem for right triangles, in △POP':

[0027] OP' 2 +PP' 2 =OP 2

[0028] (X0+R) 2 +(H-h+R) 2 = (L2 + R) 2

[0029] The draft h is

[0030]

[0031] In the formula but

[0032]

[0033] The lengths of L1 and L2 are calculated from the strong echo signal generated by the hull to the sound beam received by the side-scan sonar, that is, the draft value h is calculated.

[0034] Furthermore, the points A where the hull intersects the water surface and the highest point B of the strong echo signal at the bilge are obtained, specifically as follows:

[0035] The sampling point positions of the strongest echo signal and the second strongest echo signal are obtained from the strong echo signal of a single frame received by the side-scan sonar.

[0036] The sampling point corresponding to the strongest echo signal is point A, the intersection of the hull and the water surface.

[0037] The sampling point corresponding to the second strongest point of the echo signal is the highest point B of the strong echo signal on the bilge.

[0038] Furthermore, the lengths of L1 and L2 are calculated from the strong echo signal generated by the hull in response to the acoustic beam received by the side-scan sonar, specifically as follows:

[0039] The total number of sampling points for recording the strong echo signal in one frame is N, and the strongest point of the echo signal is the Nth point. A The sampling point is the Nth sampling point, and the second strongest point of the echo signal is the Nth sampling point. B One sampling point;

[0040] The vertical track resolution of the side-scan sonar is ΔL, then

[0041] L1 = N A ×ΔL

[0042] L2 = N B ×ΔL.

[0043] A ship draft calculation system employing the above-described ship draft calculation method includes:

[0044] The underwater sonar detection module is used to install a side-scan sonar on the bottom of one side of the channel. The side-scan sonar continuously emits sound beams towards the water surface 24 hours a day. When the side-scan sonar receives a strong echo signal generated by the ship hull to the sound beam, it is determined that the ship target has appeared.

[0045] The draft calculation module is used to calculate the draft of the hull by finding the sampling point positions of the strong reflection signal at the intersection of the hull and the water surface and the strong reflection signal at the bilge, based on the sonar data received by the side-scan sonar and in combination with the installation depth of the side-scan sonar.

[0046] A computer device includes a memory and one or more processors, the memory storing computer code that, when executed by the one or more processors, causes the one or more processors to perform the method described above.

[0047] A computer-readable storage medium storing computer code that, when executed, performs the method described above.

[0048] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0049] (1) A method for calculating the draft of inland waterway bulk carriers is provided, comprising the following steps: S1: A side-scan sonar is installed on the bottom of one side of the waterway, and the side-scan sonar continuously emits a sound beam towards the water surface 24 hours a day; S2: When the side-scan sonar receives a strong echo signal generated by the hull against the sound beam, it is determined that a ship target has appeared; S3: Based on the sonar data received by the side-scan sonar, the sampling points of the strong reflection signal at the intersection of the hull and the water surface and the strong reflection signal at the bilge are located, and the draft value of the hull is calculated in combination with the installation depth of the side-scan sonar. The above technical solution is based on the principle of acoustic echo detection and uses side-scan sonar to automatically detect the draft of inland waterway bulk carriers.

[0050] (2) Using side-scan sonar, the side-scan sonar is installed on the bottom of one side of the waterway. This not only makes it less susceptible to the influence of riverbed sand and gravel and ship anchoring, but also enables large-scale waterway monitoring. Moreover, the construction is less difficult and the equipment is easier to maintain. At the same time, the measurement accuracy is not easily affected by environmental factors such as light and water quality. Attached Figure Description

[0051] Figure 1 This is an overall flowchart of a method for calculating the draft of a ship according to the present invention;

[0052] Figure 2 This is a schematic diagram illustrating the calculation of the ship's draft according to the present invention;

[0053] Figure 3 The image shows the acoustic image of a ship target acquired by the side-scan sonar of this invention.

[0054] Figure 4 This is an overall structural diagram of a ship draft calculation system according to the present invention. Detailed Implementation

[0055] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0056] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0057] In existing technologies, commonly used acoustic measurement methods include ultrasonic ranging and multibeam echolocation.

[0058] (1) Ultrasonic ranging method

[0059] Based on the river's width, several depth sounders are laid at fixed intervals along the riverbed. Sound waves are emitted from the riverbed towards the water surface to measure the distance H from the riverbed to the water surface. h When a ship passes by, the distance H from the riverbed to the bottom of the ship is measured. c Calculate the draft as H h -H c This method has advantages such as low cost and high measurement accuracy, but its disadvantages include a small monitoring range and the equipment being easily affected by sand, silt, and anchored ships at the bottom of the riverbed, which can cause equipment damage and make maintenance difficult.

[0060] (2) Multibeam detection method

[0061] Multibeam sonar is a high-precision marine instrument commonly used to measure seabed topography and landforms. It offers advantages such as sensitivity to depth information and high data accuracy. The sonar is installed on the bottom of the riverbed and emits sound waves to the water surface. When no ships are passing, the sound waves are reflected back to the receiver. When a ship passes, in addition to the surface echo, the receiver receives reflected waves from the ship's hull. Based on these echoes, the ship's draft can be determined relatively accurately. However, this method is expensive, has a limited monitoring range, and the equipment is susceptible to damage from anchored ships.

[0062] This invention utilizes side-scan sonar to detect the draft of ships, enabling rapid calculation of the draft of bulk carriers in inland waterways with high measurement accuracy. Side-scan sonar is a device that uses echo detection to detect seabed topography and underwater targets. Typically, a single-side scanning range can reach hundreds of meters, offering advantages such as wide monitoring range, high resolution, and cost-effectiveness. This invention designs the side-scan sonar to be installed on the bottom of one side of the waterway, which is not only less affected by riverbed sand and gravel or anchored ships, but also allows for large-scale waterway monitoring. Furthermore, it is easy to install and maintain safely. The measurement accuracy is unaffected by environmental factors such as light and water quality.

[0063] The following is an illustration through specific examples:

[0064] First Embodiment

[0065] like Figure 1 As shown in the figure, this embodiment provides a method for calculating the draft of a ship, including the following steps:

[0066] S1: A side-scan sonar is installed at the bottom of one side of the channel, and the side-scan sonar continuously emits sound beams toward the water surface 24 hours a day.

[0067] Specifically, in this embodiment, the side-scan sonar is installed on the bottom of one side of the waterway. Side-scan sonar is not only less affected by riverbed sand and gravel or anchored vessels, but it also enables large-scale waterway monitoring. Furthermore, it is easy to install and maintain safely. Its measurement accuracy is also less affected by environmental factors such as light and water quality.

[0068] S2: When the side-scan sonar receives a strong echo signal generated by the ship's hull against the sound beam, it is determined that a ship target has appeared.

[0069] Specifically, in this embodiment, the side-scan sonar continuously emits sound beams towards the water surface 24 hours a day. When a ship enters the monitoring area of ​​the side-scan sonar, the ship will reflect a strong echo signal back to the sound beam. When the side-scan sonar receives the strong echo signal from the ship, it can determine that a ship target has appeared.

[0070] S3: Based on the sonar data received by the side-scan sonar, locate the sampling points of the strong reflection signals at the intersection of the hull and the water surface, and the strong reflection signals at the bilge. Combine this with the installation depth of the side-scan sonar to calculate the draft of the hull. Simultaneously, when the bilge has a curvature, the bilge's layout radius is included in the draft calculation.

[0071] Specifically, in this embodiment, such as Figure 2 As shown, the calculation process for the ship's draft is as follows:

[0072] Let the installation position of the side-scan sonar be O, the installation depth of the side-scan sonar be H, the horizontal distance between the hull and the side-scan sonar be X0, the lofting radius of the bilge be R, the lofting center of the bilge be P, the intersection of the hull and the water surface be A, the length of OA be L1, the highest point of the strong echo signal of the bilge be the intersection of OP and the bilge be B, the length of OB be L2, and the draft be h.

[0073] Draw a horizontal line through the installation position O of the side-scan sonar, and draw a vertical line through the center of the lofting circle P of the bilge. The intersection of the two lines is recorded as P'.

[0074] According to the Pythagorean theorem for right triangles, in △POP':

[0075] OP' 2 +PP' 2 =OP 2

[0076] (X0+R) 2 +(H-h+R) 2 = (L2 + R) 2

[0077] The draft h is

[0078]

[0079] In the formula but

[0080]

[0081] The lengths of L1 and L2 are calculated from the strong echo signal generated by the hull to the sound beam received by the side-scan sonar, that is, the draft value h is calculated.

[0082] Therefore, by extracting L1 and L2, i.e., the lengths of OA and OB, from the echo signals, the ship's draft can be calculated. The acoustic map formed by the side-scan sonar is mapped point-by-point according to the arrival time of the echo signals. Therefore, by obtaining the sampling point positions of the strongest and second strongest echo signals in a single frame of strong echo signals received by the side-scan sonar, the magnitudes of L1 and L2 can be obtained.

[0083] The sampling point corresponding to the strongest echo signal is point A, the intersection of the hull and the water surface; the sampling point corresponding to the second strongest echo signal is point B, the strong echo signal at the bilge.

[0084] The total number of sampling points for recording the strong echo signal in one frame is N, and the strongest point of the echo signal is the Nth point. AThe sampling point is the Nth sampling point, and the second strongest point of the echo signal is the Nth sampling point. B One sampling point;

[0085] The vertical track resolution (range resolution) of the side-scan sonar is ΔL, then

[0086] L1 = N A ×ΔL

[0087] L2 = N B ×ΔL.

[0088] Substituting L1 and L2 into the above formula, the draft h can be calculated.

[0089] Second Embodiment

[0090] like Figure 4 As shown, this embodiment provides a ship draft calculation system that employs the ship draft calculation method as described in the first embodiment, including:

[0091] The underwater sonar detection module 1 is used to install a side-scan sonar on the bottom of one side of the channel. The side-scan sonar continuously emits a sound beam towards the water surface 24 hours a day. When the side-scan sonar receives a strong echo signal generated by the hull to the sound beam, it is determined that a ship target has appeared.

[0092] The draft depth calculation module 2 is used to find the sampling point positions of the strong reflection signal at the intersection of the hull and the water surface and the strong reflection signal at the bilge based on the sonar data received by the side-scan sonar, and calculate the draft depth of the hull in combination with the installation depth of the side-scan sonar.

[0093] A computer-readable storage medium stores computer code that, when executed, performs the methods described above. Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. This program can be stored in a computer-readable storage medium, which may include: read-only memory (ROM), random access memory (RAM), a magnetic disk, or an optical disk, etc.

[0094] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

[0095] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0096] It should be noted that the above embodiments can be freely combined as needed. The above description is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for calculating the draft of a ship, characterized in that, Includes the following steps: S1: A side-scan sonar is installed at the bottom of one side of the channel, and the side-scan sonar continuously emits sound beams toward the water surface 24 hours a day. S2: When the side-scan sonar receives a strong echo signal generated by the ship's hull against the sound beam, it is determined that a ship target has appeared; S3: Based on the sonar data received by the side-scan sonar, find the sampling point positions of the strong echo signal at the intersection of the hull and the water surface and the strong echo signal at the bilge, and calculate the draft of the hull by combining the installation depth of the side-scan sonar. Step S3 also includes: When the bilge has an arc, the lofting radius of the bilge is included in the calculation of the draft. Specifically, based on the sonar data received by the side-scan sonar, the sampling points of the strong echo signal at the intersection of the hull and the water surface and the strong echo signal at the bilge are located. The draft of the hull is then calculated by combining this with the installation depth of the side-scan sonar. Let the installation position of the side-scan sonar be O, the installation depth of the side-scan sonar be H, the horizontal distance between the hull and the side-scan sonar be X0, the lofting radius of the bilge be R, the lofting center of the bilge be P, the intersection of the hull and the water surface be A, the length of OA be L1, the highest point of the strong echo signal of the bilge be the intersection of OP and the bilge be B, the length of OB be L2, and the draft be h. Draw a horizontal line through the installation position O of the side-scan sonar, and draw a vertical line through the center of the lofting circle P of the bilge. The intersection of the two lines is recorded as P'. According to the Pythagorean theorem for right triangles, in ΔPOP': ON' 2 +PP' 2 =OP 2 (X0+R) 2 +(H-h+R) 2 =(L2+R) 2 The draft h is In the formula but The lengths of L1 and L2 are calculated from the strong echo signal generated by the hull to the sound beam received by the side-scan sonar, that is, the draft value h is calculated.

2. The method for calculating ship draft according to claim 1, characterized in that, Also includes: Specifically, the strong echo signal B at the intersection point A of the hull and the water surface and the bilge are obtained as follows: The sampling point positions of the strongest echo signal and the second strongest echo signal are obtained from the strong echo signal of a single frame received by the side-scan sonar. The sampling point corresponding to the strongest echo signal is point A, the intersection of the hull and the water surface. The sampling point location corresponding to the second strongest point of the echo signal is the strong echo signal B of the bilge.

3. The method for calculating ship draft according to claim 2, characterized in that, The lengths of L1 and L2 are calculated from the strong echo signal generated by the hull in response to the acoustic beam received by the side-scan sonar, specifically as follows: The total number of sampling points for recording the strong echo signal in one frame is N, and the strongest point of the echo signal is the Nth point. A The sampling point is the Nth sampling point, and the second strongest point of the echo signal is the Nth sampling point. B One sampling point; The vertical track resolution of the side-scan sonar is ΔL, then L1=N A ×ΔL L2=N B ×ΔL。 4. The method for calculating ship draft according to claim 1, characterized in that, Also includes: The echo signals received by the side-scan sonar in each transmission cycle are arranged and displayed in time to form an acoustic map of the hull. The acoustic image shows the linear outline of the side of the hull.

5. The method for calculating ship draft according to claim 4, characterized in that, Also includes: In the acoustic diagram, grayscale is used to represent the intensity of the echo signal, with bright colors representing strong signals and dark colors representing weak signals. The bright colors in the acoustic diagram represent the upper and lower edges of the ship's outline.

6. A ship draft calculation system employing the ship draft calculation method as described in any one of claims 1-5, characterized in that, include: The underwater sonar detection module is used to install a side-scan sonar on the bottom of one side of the channel. The side-scan sonar continuously emits sound beams towards the water surface 24 hours a day. When the side-scan sonar receives a strong echo signal generated by the ship hull to the sound beam, it is determined that the ship target has appeared. The draft calculation module is used to locate the sampling points of the strong echo signals generated by the sound beam at the intersection of the hull and the water surface and the strong echo signals at the bilge, based on the strong echo signals generated by the sonar data received by the side-scan sonar, and to calculate the draft value of the hull in combination with the installation depth of the side-scan sonar.

7. A computer device comprising a memory and one or more processors, the memory storing computer code that, when executed by the one or more processors, causes the one or more processors to perform the method as described in any one of claims 1 to 5.

8. A computer-readable storage medium storing computer code, wherein when the computer code is executed, the method of any one of claims 1 to 5 is performed.

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