Ship area keeping control method based on position offset calculation

Abstract

The invention relates to a ship area keeping control method based on position offset calculation, which comprises the following steps of: (1) inputting closed polygon outer boundary points of ship dynamic positioning area keeping, setting a specific area in the outer boundary as an inner boundary, and controlling a ship to move to the center of an area keeping area; (2) stopping the control on the ship propeller, so that the ship floats freely along with the environmental force; if the ship moves to the inner boundary, the direction of a connecting line of the current position of the ship and the regional centroid position is calculated, and the direction is recorded as the optimal heading direction of the ship; (3) the ship is controlled to move back to the position where the area keeps the center, and then control over the longitudinal position and the transverse position of the ship is closed; (4) when the ship floats to the inner boundary under the action of environmental force, recalculating the direction of the connecting line of the current position of the ship and the area centroid position, and updating the optimal heading direction; and (5) moving the ship to the area to keep the center, and repeating the operations from the step (3) to the step (4).

Description

Technical Field

[0001] This invention relates to a ship positioning technology, and more particularly to a ship area-keeping control method based on position offset calculation. Background Technology

[0002] With the development of the world economy, energy and resource issues have become increasingly prominent, and marine mineral resources have become a focus of attention. Dynamic positioning technology can enable ships to maintain a certain position and orientation at sea, regardless of water depth, making it an indispensable support system for offshore mining and engineering operations. Dynamic positioning area-keeping technology mainly uses the thrust generated by controlling the propeller to keep the ship within a certain operating area and maintain the ship in the optimal heading direction, reducing the energy consumed in ship positioning and achieving the best energy-saving effect.

[0003] A crucial aspect of area keeping for ships is finding the optimal heading, which determines the energy consumption for area keeping. Traditional power-based and force-based fuzzy control methods require the ship to rotate 360 ​​degrees and select the optimal angle for keeping and controlling based on the energy consumption or force generated by the lateral thrust. However, the entire process involves long search times and high energy consumption. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a ship area holding control method based on position offset calculation, which simplifies the heading optimization process.

[0005] The technical solution of the present invention is: a ship area holding control method based on position offset calculation, comprising the following steps: (1) inputting the outer boundary point of the closed polygon of the ship dynamic positioning area holding, and setting a specific area within the outer boundary as the inner boundary, and controlling the ship to move to the center of the area holding area; (2) turning off the control of the ship's propeller, so that the ship drifts freely with the environmental force; if the ship moves to the inner boundary, calculate the direction of the line connecting the ship's current position and the centroid position of the area, and record the direction as the ship's optimal heading direction; (3) controlling the ship to move back to the position of the area holding center, and then turning off the longitudinal and lateral position control of the ship, and only maintaining the control of the ship's heading degree of freedom, so that the ship's heading is maintained at the optimal heading; (4) waiting for the ship to drift to the inner boundary under the action of the environmental force, recalculating the direction of the line connecting the ship's current position and the centroid position of the area, and updating the optimal heading direction; (5) moving the ship to the area holding center, and repeating the operation of steps (3) to (4).

[0006] Further, in step (1), the center point of the region is determined by the centroid position calculated from the points of the closed outer boundary polygon, and the latitude and longitude coordinates of this centroid position are ( , ).

[0007] Furthermore, in step (2), the optimal heading direction is recorded as follows: ψ target .

[0008] 4. The ship area holding control method based on position offset calculation according to claim 3, characterized in that, the ψ target The calculation method is as follows: if the ship's latitude and longitude coordinates are ( , When ), the northward distance is calculated as follows: The eastward distance is calculated as follows: , R Given the Earth's average radius, the optimal heading of the ship is... .

[0009] Furthermore, in step (3), the control of the bow freedom of the ship is achieved by activating the thrust generated by the propeller.

[0010] Furthermore, before performing step (1), the ship's dynamic positioning control system is activated.

[0011] The beneficial effects of this invention are as follows:

[0012] This invention proposes a ship area holding control method based on position offset calculation, which can calculate the ship's optimal heading using the ship's motion trajectory, avoiding the time waste and energy loss of searching for area holding by rotating the ship.

[0013] This invention obtains the optimal heading for maintaining the ship's heading based on the ship's position during the ship's motion, thereby reducing the energy consumption and time required for heading optimization. The control method is simple and reliable. Attached Figure Description

[0014] Figure 1 This is the control flowchart of the present invention; Figure 2 This is a schematic diagram of the first step of the control process of the present invention; Figure 3 This is a schematic diagram of step 2 of the control flow of the present invention; Figure 4 This is a schematic diagram of step 3 of the control flow of the present invention; Figure 5 This is a schematic diagram of step 4 of the control flow of the present invention; Figure 6 This is a schematic diagram of step 5 of the control flow of the present invention; Figure 7 This is a schematic diagram of step 6 of the control flow of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0016] like Figure 1 As shown in the figure, an embodiment of the present invention provides a ship area holding control method based on position offset calculation, the steps of which are as follows: (1) First, input the outer boundary point of the dynamic positioning region, and calculate the outer boundary, inner boundary, and center point of the region based on the outer boundary point. The latitude and longitude coordinates are ( , ),like Figure 2 As shown.

[0017] (2) If the entered area boundary points do not meet the requirements, they need to be re-entered. If the entered area maintenance boundaries meet the requirements, activate the dynamic positioning system to move the vessel to the area maintenance center, such as... Figure 3 As shown.

[0018] (3) Turn off the dynamic positioning control system to control all propellers, allowing the ship to drift freely under the influence of environmental forces to the inner boundary of the ship's area, such as... Figure 4 As shown.

[0019] (4) Calculate the direction of the line connecting the ship's current position and the area maintenance center as the optimal heading for area maintenance, denoted as ψ target ,like Figure 5 As shown. Assume the ship's latitude and longitude coordinates are ( , ). ψ target The calculation method is as follows: The northward distance is calculated as follows: The eastward distance is calculated as follows: , R Given the Earth's average radius, the optimal heading of the ship is... .

[0020] (5) Activate the propellers, control the ship to move to the area holding center, deactivate control over the ship's lateral and longitudinal degrees of freedom, and control only the ship's bow degree of freedom to maintain ψ target ,like Figure 6 As shown.

[0021] (6) Since the longitudinal and lateral motion of the ship was not controlled, the ship moved to the inner boundary of the area maintenance zone under the action of environmental forces. At this time, the direction of the line connecting the ship's current position and the center of the area maintenance zone was recalculated as the new optimal heading for area maintenance, denoted as . ψ target Repeat steps (5) and (6) above until the vessel area retention function ends, such as Figure 7 As shown.

[0022] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for ship area-keeping control based on position offset calculation, characterized in that, The process includes the following steps: (1) Input the outer boundary point of the closed polygon maintained by the dynamic positioning area of ​​the ship, and set a specific area within the outer boundary as the inner boundary, and control the ship to move to the center of the area maintained by the region; (2) Turn off the control of the ship's propellers, and let the ship drift freely with the environmental forces; if the ship moves to the inner boundary, calculate the direction of the line connecting the ship's current position and the centroid of the region, and record this direction as the ship's optimal heading direction; (3) Control the ship to move back to the position of the center of the region maintained by the region, and then turn off the longitudinal and lateral position control of the ship, and only maintain the control of the ship's heading degree of freedom, so that the ship's heading is maintained at the optimal heading; (4) When the ship drifts to the inner boundary under the action of the environmental forces, recalculate the direction of the line connecting the ship's current position and the centroid of the region, and update the optimal heading direction; (5) Move the ship to the center of the region maintained by the region, and repeat the operation of steps (3) to (4).

2. The ship area holding control method based on position offset calculation according to claim 1, characterized in that, In step (1), the center point of the region is determined by the centroid position calculated from the points of the closed outer boundary polygon, and the latitude and longitude coordinates of the centroid position are ( , ).

3. The ship area holding control method based on position offset calculation according to claim 2, characterized in that, In step (2), the optimal heading direction is recorded as follows: ψ target .

4. The ship area holding control method based on position offset calculation according to claim 3, characterized in that, The ψ target The calculation method is as follows: if the ship's latitude and longitude coordinates are ( , When ), the northward distance is calculated as follows: The eastward distance is calculated as follows: , R Given the Earth's average radius, the optimal heading of the ship is... .

5. The ship area holding control method based on position offset calculation according to claim 1, characterized in that, In step (3), the control of the bow degree of freedom of the ship is achieved by activating the thrust generated by the propeller.

6. The ship area holding control method based on position offset calculation according to claim 1, characterized in that, Before performing step (1), activate the ship's dynamic positioning control system.

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